# Oral-History:Walter Welkowitz

(Difference between revisions)
 Revision as of 20:11, 10 December 2008 (view source)Nbrewer (Talk | contribs)← Older edit Revision as of 14:51, 23 January 2009 (view source)Nbrewer (Talk | contribs) Newer edit → Line 1,883: Line 1,883: '''Welkowitz:''' '''Welkowitz:''' − Yes. It is a very difficult problem but there have been some solutions. One would like to do what is called inverse electrocardiography. Let us assume that you make twelve electrode measurements around the body. Can you then describe the electrical source as an inversion problem? It turns out that this is a very difficult mathematical problem. People have made some headway, especially with computers, in solving the inverse problem. A solution will give you much more knowledge of the electrical activity of the heart. If you make some assumptions about heart shape or even use a real heart shape, you might be able to tell, for example, where defects are and if they are not being electrically excited. A number of medical inverse problems that you would like to solve are difficult. The best results came from the imaging systems such as CAT scans and MRI’s where people solved the inverse problem. Using external measurements there is a mathematical procedure to get the inverse so one can actually see the image of an inside structure from the outside measurements. That success created much interest in inverse problems. That technique is one of the major successes of biomedical engineering.
+ Yes. It is a very difficult problem but there have been some solutions. One would like to do what is called inverse electrocardiography. Let us assume that you make twelve electrode measurements around the body. Can you then describe the electrical source as an inversion problem? It turns out that this is a very difficult mathematical problem. People have made some headway, especially with computers, in solving the inverse problem. A solution will give you much more knowledge of the electrical activity of the heart. If you make some assumptions about heart shape or even use a real heart shape, you might be able to tell, for example, where defects are and if they are not being electrically excited. A number of medical inverse problems that you would like to solve are difficult. The best results came from the imaging systems such as [[CAT, MRI, and Ultrasound|CAT scans and MRI’s]] where people solved the inverse problem. Using external measurements there is a mathematical procedure to get the inverse so one can actually see the image of an inside structure from the outside measurements. That success created much interest in inverse problems. That technique is one of the major successes of biomedical engineering.

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− [[Category:People_and_organizations]] [[Category:Engineers]] [[Category:Universities]] [[Category:Corporations]] [[Category:Bioengineering]] [[Category:Biomedical_engineering]] [[Category:Biomedical_equipment]] [[Category:Biomedical_transducers]] [[Category:Catheters]] [[Category:Medical_treatment]] [[Category:Cardiology]] [[Category:Biomedical_computing]] [[Category:IEEE]] [[Category:Culture_and_society]] [[Category:Education]] [[Category:Engineered_materials_&_dielectrics|Category:Engineered_materials_&_dielectrics]] [[Category:Ultrasonics,_ferroelectrics,_and_frequency_control]] [[Category:Ultrasonic_imaging]] + [[Category:People_and_organizations]] [[Category:Engineers]] [[Category:Universities]] [[Category:Corporations]] [[Category:Bioengineering]] [[Category:Biomedical_engineering]] [[Category:Biomedical_equipment]] [[Category:Biomedical_transducers]] [[Category:Catheters]] [[Category:Medical_treatment]] [[Category:Cardiology]] [[Category:Biomedical_computing]] [[Category:IEEE]] [[Category:Culture_and_society]] [[Category:Education]] [[Category:Engineered_materials_&_dielectrics|Category:Engineered_materials_&_dielectrics]] [[Category:Ultrasonics,_ferroelectrics,_and_frequency_control]] [[Category:Ultrasonic_imaging]] [[Category:Ultrasonic_transducers]] − + − [[Category:Engineered_materials_%26_dielectrics]] + − [[Category:Ultrasonics%2C_ferroelectrics%2C_and_frequency_control]] + − [[Category:Ultrasonic_transducers]] +

## Contents

Welkowitz received his BS in Electrical Engineering from Cooper Union, then his PhD in EE from the University of Illinois (1954). At Illinois he went into biomedical engineering as a student in William Fry’s bioacoustics laboratory; Welkowitz’s thesis was on ultrasonic effects on muscle. He then spent most of a decade at Gulton Industries working on medical instrumentation—an intracardiac catheter microphone, an intracardiac pressure gauge, and a physiological monitoring system. He then became a professor at Rutgers University’s Electrical Engineering Department. While there he was chair for two long stints. He also started up a biomedical engineering program within the EE department, progressing from a Masters programs to a Doctoral program to a department in its own right (1987). His research has included work on the use of computers in medicine, control systems for heart assist devices, books on biomedical instruments and engineering hemodynamics (blood flow), and engineering-informed indices of cardiac status. He believes that visual imaging systems have been the greatest success story in biomedical engineering, and the greatest contributor to engineers’ rising status in the medical world. After them, he cites pacemakers and monitoring systems as the most significant contributions.

WALTER WELKOWITZ: An Interview Conducted by Frederick Nebeker, IEEE History Center, 18 October 1999

Interview # 374 for the IEEE History Center, The Institute of Electrical and Electronics Engineering, Inc., and Rutgers, The State University of New Jersey

This manuscript is being made available for research purposes only. All literary rights in the manuscript, including the right to publish, are reserved to the IEEE History Center. No part of the manuscript may be quoted for publication without the written permission of the Director of IEEE History Center.

Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, Rutgers - the State University, 39 Union Street, New Brunswick, NJ 08901-8538 USA. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.

It is recommended that this oral history be cited as follows:
Walter Welkowitz, an oral history conducted in 1999 by Frederik Nebeker, IEEE History Center, Rutgers University, New Brunswick, NJ, USA.

## Interview

Interview: Walter Welkowitz
Interviewer: Frederik Nebeker
Date: 18 October 1999
Place: Rutgers’ Busch Campus, Piscataway, New Jersey

### Childhood, family, and educational background

Nebeker:

Tell me a little bit about your family, and where and when you were born.

Welkowitz:

I was born in Brooklyn, New York in 1926.

Nebeker:

Welkowitz:

My father was math chairman in a New York City high school.

Nebeker:

In those days, not many women were out in the work place.

Welkowitz:

Yes. My mother did not work.

Nebeker:

Did you have siblings?

Welkowitz:

Yes. I have one sister, and she worked on and off teaching in elementary school. Her husband, before he retired, was an editor of Changing Times.

Nebeker:

Did your father influence you to go into engineering?

Welkowitz:

Not specifically into engineering, but I think he recognized that my interests were in mathematics and physics.

Nebeker:

Were you interested in radio as a youngster?

Welkowitz:

Not particularly. I did not build radio sets and things like that.

Nebeker:

You were more interested in math and physics?

Welkowitz:

Yes. I was always very interested in mathematics.

Nebeker:

I see. Did you go to public schools?

Welkowitz:

Yes, I went to the public schools in Brooklyn. Actually, I went to Erasmus Hall High School, which I think is the oldest high school in New York.

Nebeker:

Did you get a good high school education?

Welkowitz:

Yes, a very good one at that time. I do not think the schools are necessarily good now, but at that time Erasmus Hall was a very good school. It was very strong in math. As an activity for people interested in math, it had a very strong math club that participated in contests. In fact, one of the recent chairs of math at Berkeley and one of the math professors at Princeton were in the math club when I was.

Nebeker:

Welkowitz:

No, this was not one of the specialized schools. Where we lived it happened to be the neighborhood high school. It was a very large high school. It had quite a mix of people so that it had quite a number of very good students and faculty.

Nebeker:

Did you come out of high school thinking that you wanted to become a mathematician?

### College education and naval service

Welkowitz:

No. At that time I did not want to be a teacher, although obviously I became one eventually. I thought engineering would be a good choice. I attended Cooper Union.

Nebeker:

Today they provide full scholarships. Was that available to you back then?

Welkowitz:

Yes. As far as I know it has always been that way. The money they have from Peter Cooper has supported them, with some other help, all these years.

Nebeker:

That was some achievement then to get in. I know it is extremely difficult these days to get into Cooper Union, and I am sure it was then also.

Welkowitz:

Yes. It was a limited admission type of school.

Nebeker:

I assume that was a very good experience.

Welkowitz:

Yes, although I had a split college career. About half way through I went into the Navy in 1944, since that was during World War Two.

Nebeker:

Did you have to go into the Navy?

Welkowitz:

Yes. At that time the war was still on.

Nebeker:

Were there deferments to get you through college?

Welkowitz:

No. At that time going into the service was a very honorable activity.

Nebeker:

I know there were people who quit what they were doing and signed up, but I just wondered if someone could complete their four years.

Welkowitz:

No. I was eighteen in 1944.

Nebeker:

So you were eligible for the draft?

Welkowitz:

Yes.

Nebeker:

What did you do in the Navy?

Welkowitz:

I was an electronic technician, since I had enough experience from the first couple of years in Cooper Union to do that kind of work.

Nebeker:

Did you take some test to get into that, or they just asked you?

Welkowitz:

No. They decided my background was oriented that way. I actually went to the various Navy schools where one learned how to service radar and sonar.

Nebeker:

Two other people I talked to, Jack Reid and Larry Katz, were also in the Navy in essentially that program. That was a spawning ground for biomedical engineers.

Welkowitz:

It was interesting, because it was a very advanced program. The Navy taught mathematics and electronics to people who needed it. They had you actually work on very complex equipment and, by troubleshooting, get to know it inside and out.

Nebeker:

Did you have much experience with actually building electronic equipment?

Welkowitz:

In the Navy, but not before that. In the program one had to build equipment.

Nebeker:

Were you in the EE program at Cooper Union?

Welkowitz:

Yes.

Nebeker:

Did you choose that because it seemed like a more promising career path?

Welkowitz:

Probably. Since my dad was a math teacher, his idea at that time was that most mathematicians taught in high school or college. Since I was not interested in that as a career, the engineering school seemed like the reasonable choice. In Cooper Union they had excellent students, so it seemed like a good choice.

Nebeker:

You had two years in college and then went into the Navy?

Welkowitz:

Yes. I came back and finished up at Cooper Union.

### Graduate studies, University of Illinois

#### Electrical engineering and mathematics

Welkowitz: At that time I faced the big decision whether to go to work in some company or go to some graduate school? I did some interviewing but I decided to go to graduate school. I was able to get as assistantship at the University of Illinois where they had a very outstanding electrical engineering department.

Nebeker:

As an undergraduate, what type of EE did you study?

Welkowitz:

At Cooper Union everybody did the same thing, which was everything. We studied electronics but we also studied a lot of machinery. In fact, that was useful when I went to Illinois, which was clearly a very electronics oriented place. They needed graduate assistants for the machinery labs because most of their graduate students had not gone that route. I had much more machinery experience than others did, so I taught that for a year.

Nebeker:

Were you more interested in electronics yourself?

Welkowitz:

In Illinois as a graduate student, I studied a lot of math. In fact, fifty percent of all my course work was in the math department. That was very unusual.

Nebeker:

I would think so. What was your idea in taking so much math?

Welkowitz:

The various things I studied in engineering involved math. I took courses in subjects like antennas and advanced circuit design. The math was a natural choice. I did not study applied math; but I studied abstract algebra and various things of that nature. It seemed to fit in and it did not bother anybody in the EE department. The EE department there was very broad in its interests, and that is where I got involved in what we now would call biomedical engineering. Once I got there, I looked at various possibilities for assistantships.

#### Bioacoustics lab; ultrasonic effects on muscle

Welkowitz:

I had originally been a teaching assistant in machinery laboratories, but that was not a research activity and I was interested in doing research. I was offered an assistantship but got in with Bill Fry from the group bioacoustics laboratory. The laboratory was in electrical engineering but he clearly was oriented toward bioacoustics.

Nebeker:

That was not because of any previous position in that kind of engineering, but because it was a research lab.

Welkowitz:

The work they were doing looked interesting. I spent the rest of my time at Illinois in that laboratory.

Nebeker:

What projects was Bill Fry’s group doing?

Welkowitz:

The major ones were ultrasonic projects. The strongest area was probably in ultrasonic effects on nerves, and the group ultimately developed equipment for radiating various brain regions to correct disorders. While everyone was somewhat involved in that program I did a Ph.D. thesis on ultrasonic effects on muscle.

Nebeker:

Like a diathermy treatment?

Welkowitz:

We were able to prove that our effect was not diathermy, but was something else.

Nebeker:

Wasn’t ultrasonic diathermy a well-known therapy at the time?

Welkowitz:

Yes. It was not very good but it was very well known. My thesis explored what the possibilities for mechanisms were, and then tried to study non-thermal ones.

Nebeker:

Were the mechanisms stimulating the muscle?

Welkowitz:

No, effecting the muscle. In the experiments I did, I clearly kept the muscle cool. I used frog muscles and I isolated them. I learned a lot of muscle physiology at that time. The chair of physiology at Illinois was a muscle physiologist, so he was very interested in my work. The people in physiology taught me how to cut up frogs, mount and excite muscle, and use curare to block electrical excitation. I got a very good grounding in the physiology of muscle. The experiments were designed to cool down the muscle very greatly, and then calculate the heating that you would get from the sound. In my experiments the muscle did not heat above what muscle would normally be in the body. There were levels of sound where one could get blockage of the contraction of the muscle. I studied the dosages and the frequencies fore these effects.

Nebeker:

What was the motivation for that kind of research?

Welkowitz:

The motivation was really just to learn about the muscle and to learn about effects of sound. The research was supported by a group at Wright Field who were generally interested in sound effects on everything related to physiology.

Nebeker:

Like what pilots were subjected to?

Welkowitz:

I guess they considered that as a possibility, but this was a strong research group at Wright Field. There might be more applied applications, but the group was very interested in knowing the mechanisms and sound levels involved, and in particular, which sound levels could block muscle. The frequencies I used were in the megahertz range, and obviously that is not anything that pilots are normally going to be subjected to.

Nebeker:

It was not the health concerns generally?

Welkowitz:

Later when the group there and some other groups around the country did work on using sound to destroy local regions in the brain, it was very important to know what levels would cause destruction. This interest fit in well with the rest of the group at Illinois.

Nebeker:

It was more basic biophysics?

Welkowitz:

Yes. For that reason I published my thesis in what was then the Journal of Cellular and Comparative Physiology, which was one of the top physiology journals at that time. They were normally not prone to publish engineering papers. I think that is now the journal Cell.

Nebeker:

They thought it was sufficiently important to accept it?

Welkowitz:

Yes they did.

Nebeker:

Welkowitz:

Bill Fry. He was very knowledgeable and got to be very well known for explaining ultrasonic effects in physiology. The interest probably got broader later when people began to do imaging with sound. There was always the question of whether the levels of sound used could do some damage; but they were generally much lower than the levels needed for that did destruction effect. For my thesis I looked into the mechanisms and cooled the muscles so that it was not a heating effect. I also suppressed cavitation with pressures on the liquid in which the muscle was immersed so the mechanism was not cavitation breaking up things in the cell. I wrote a paper speculating on whether the effect was one to the tearing apart of complex molecule structures. I do not think that to this day people have a very good understanding of what the mechanism is, except that the effects were very repeatable. (I studied a few thousand frogs.)

Nebeker:

Is the effect such that it is something that has to be taken into account when you do imaging?

Welkowitz:

No, not when you do imaging. It took much higher levels of sound to produce these effects which was a good thing to know. When people first did imaging, I do not think they really knew what the sound would do other than make pictures.

#### Ultrasonic transducer design, computer cell counter

Nebeker:

Were you also involved with the apparatus to generate the ultrasound?

Welkowitz:

Yes, I designed some of it. We had a pretty sophisticated group. We had a machinist and an electronic technician to build the electronics, but I designed some of the electronics and the transducer that I used.

Nebeker:

Was it something that was used later in other studies by you or others?

Welkowitz:

Yes, but also for the nerve work people designed much more complex transducers. Bill’s brother, Frank Fry, who is retired from the University of Indiana in Indianapolis, was a very talented mechanical designer and a mechanical engineer. He guided all of us in mechanical design. For the nerve work he built a multi-headed transducer arrangement with four focusing heads that could be moved around to get very high intensities within a cubic millimeter, which at that time was very unique. In terms of the brain studies, if you took off the top of the skull you could utilize this transducer and actually just damage a cubic millimeter of nervous and not have broad damaging.

Nebeker:

Has that been a useful therapy?

Welkowitz:

The group used did it for a while to treat Parkinson’s Disease at a number of institutions. I think what ultimately happened is that a procedure using cooling probes was simpler. I think that is what is probably used now.

Nebeker:

All this time, after the first year, you worked in Bill Fry’s group and on your dissertation?

Welkowitz:

Yes. I also did some other things because I had a good friend who was working in the original computer laboratory at Illinois. At that time Illinois was building the ORDVAC and the ILLIAC I. I had a friend in that group, so I did two projects there. I designed an ultrasonic transducer using the ORDVAC. At that time there were only about a half of dozen electronic computers in the world. I did something more interesting on the ILLIAC I. On the bioacoustics laboratory nerve project, when they were destroying neuron sections, they had people count up how many cells were destroyed. One looks in a microscope and count destroyed cells in a region. I got interested in whether one could do this automatically. At that time there were some experimental flying spot scanners on microscopes, where the image was projected onto a pickup tube and scanned. I did not get involved in counting and sizing the scanning equipment, but I was interested in whether one could program the ILLIAC I computer for using such equipment. I actually fed in simulated images from such a scanner, with the goal being to count and size them for any shape of cell. If you had cells of different shapes, it would tell you that there were five in this size range and twenty-three in that size range. I published this work in the Review of Scientific Instruments in 1954. As far as I know it was the first computer vision work published.

Nebeker:

It sounds incredibly early, and I know later on these blood cell counters succeeded.

Welkowitz:

This was much earlier, and the algorithm counted cells individually. It actually scanned, so it counted every single cell that was in the field. The reason I am pretty sure it was the first was that a few years ago there was some patent litigation going on in that field. Computer vision ultimately led to automatic examining of manufactured products for quality control. There was some question on invention priorities. One of the patent attorney groups did a thorough literature search, and they found this publication. They were quite interested.

Nebeker:

They found the publication? You did not patent this?

Welkowitz:

Yes, they found it. When I was a graduate student we wrote papers not patents. I guess we did not do that.

Nebeker:

It might have been worth something.

Welkowitz:

Yes, it would have. The patent attorneys had me go over the whole thing with them. They were using the paper to establish priority ahead of some other patents.

Nebeker:

Did you carry on at all in this line of work?

Welkowitz:

No, I did not. I did it mostly because I was in the group and it was interesting. As a graduate student you tend to like to play around with a lot of things. I did not follow that up.

Nebeker:

It sounds like it would be a very difficult thing to do with these very early computers.

Welkowitz:

With the early computers, yes. Now what I did could be done on a hand-held calculator with a screen. At that time, the computers had very trivial memories and it was very difficult to use them in this mode.

Nebeker:

Also, it was significant to recognize a cell.

Welkowitz:

Yes, that was the heart of the algorithm. I only kept two scan lines at a time because the computer could hold take thousands of scan lines. I had to tie pieces together. For example, if the cell was U-shaped and you thought you were getting two pieces, at some point you had to tie them together because it was one cell. The algorithm did all of that and it actually worked fine; there was no problem with it. I put in 100 scans for cells of all different shapes and sizes and it got them all right, so it actually could do perform as required.

Nebeker:

Do you know if it got picked up on?

Welkowitz:

At that time, the only place I knew about was the Review of Scientific Instruments, which is still a journal of the Physical Society.

Nebeker:

I do not know when it was, but cell counters became important later on. But here you had a program that was doing that very early.

Welkowitz:

I think the approach was more interesting later when people were doing more involved computer vision. I understand that even just using two scan lines and tying the images together was interesting to a lot of people. I have to admit I never worked in that field, so I am not that familiar with that history.

#### Crystal acoustic arrays

Nebeker:

Your very early work is just fascinating and very interesting. Another thing that caught my eye in your very early publications was crystal acoustic arrays.

Welkowitz:

Yes. I guess Bill Fry had worked for the Navy before he came to Illinois. He was very interested in designing special acoustic arrays. In fact, that is how the group got into these specialized devices for radiating the brain. Bill also had a project from the Navy on variable resonant frequency transducers. The analysis was very involved. It was not that the equations were so complicated, but to get answers for a transducer with a backing (we used mercury backing because one could vary that by just turning a knob) radiating into a liquid involved very extensive calculations. I carried out the calculations on the ORDVAC computer, since I got to know a little bit about using computers. The only problem was that the computer would just print out long lists of numbers. We had to have somebody plot curves from the numbers. Nowadays, the computer plots it. That too got published.

Nebeker:

That was giving the field generated by these transducers?

Welkowitz:

More than that it gave you the intensities as a function of the amount of mercury backing. We plotted these continuously. One got to feel how the intensities and the beam shifted with the backing. That was very interesting for people who do transducer design.

#### Computers and programming

Nebeker:

How was it programming way back to the ILLIAC?

Welkowitz:

It was great, but it probably was bad for me because it was before anyone had developed modern programming languages.

Nebeker:

Welkowitz:

No, it was long before that. One wrote code; for example, “Move something from this register to that register, or into the memory.” Of course, that is not how one would program now. Actually, since Illinois was building these two computers they were giving some courses in programming. They brought somebody over from Cambridge to teach it. It was very laborious programming because you wrote out all these sequential orders that you now call up with a single command.

Nebeker:

Did you enter it into the computer on punch cards?

Welkowitz:

No.

Nebeker:

On punch paper tapes?

Welkowitz:

Yes, paper tape.

Nebeker:

So debugging was probably a pretty onerous thing?

Welkowitz:

Oh, yes, every aspect of it. Using these computers was very tedious. We were very fortunate that they had done a good design. The computers would run without a failure for a fairly long time, but the computers must have had ten or twenty thousand tubes in them so that there would be failures every day or two. If you could run a program all the way through, your were very lucky.

Nebeker:

I know Illinois was very early in getting computers running.

Welkowitz:

Yes. The people there were associated with von Neumann and they were building essentially the same kind of computer as he was building at the Institute for advanced study. The ORDVAC was being built for the ordinance people. The University had decided they would only do this if they could, at the same time, build one to keep at Illinois, that was the ILLIAC I. They built the two of them, essentially simultaneously.

Nebeker:

Did you continue to use computers in your work?

Welkowitz:

Not a lot.

#### Physiology, ultrasonics in medicine

Welkowitz:

Once I got working on my muscle project I spent more and more time learning physiology, and I got very interested in that.

Nebeker:

Did you ever actually take classes in physiology or other biology classes?

Welkowitz:

No, but one of the professors in physiology spent much of his time in our group. He gave us informal lectures. I learned a lot of physiology. When I first came to Rutgers the professor teaching graduate physiology asked that I introduce some material on engineering concepts in physiological control systems. So, for about ten years, I would lecture for two or three weeks in the graduate physiology course here at Rutgers. I knew enough physiology to do that.

Nebeker:

There was another fairly early publication of yours in Proceedings of the IRE, "Ultrasonics in Medicine and Dentistry."

Welkowitz:

Yes. What I did at that time was to try to summarize, at least up to that date, the state of the field. I did that to the best of my knowledge. The paper included imaging, radiation, and diathermy.

Nebeker:

I am sure that is something I should take a look at. It gives an early picture of ultrasonics.

Welkowitz:

Yes.

Nebeker:

Was Bill Fry’s group doing imaging also?

Welkowitz:

Not at that time. He did set up a series of meetings at Illinois where he had all the people working in medical ultrasonics. People came in and presented what they were doing, so we were fairly current. That is where I met Jack Reid since he was doing ultrasonic imaging. He was working with Dr. Wild, a physician at the University of Minnesota. All the different people who were working in ultrasonics in medicine met together. Bill Fry was considered to be outstanding, and people came from many places to meet with the group. For example, while I was there Herman Schwan came because he was interested in mechanisms of electronic and acoustic interaction with tissue. The group with McCullough and Pitts came out from MIT because Bill Fry was doing brain irradiation and they were very interested in a more rigorous approach to studying the brain. McCullough and Pitts did the original worked on neural networks.

#### Relationships between biophysics and bioengineering

Nebeker:

I remember Schwan telling me that he was looking more at electromagnetic fields and impedance of tissue, and that his main idea was to try and understand the physics of these biological materials. It sound like at least your thesis was related to this.

Welkowitz:

Yes. It was based more on the mechanical properties of the tissue, rather than the electromagnetic properties.

Nebeker:

Rather than traditional engineering where you are trying to achieve some effect.

Welkowitz:

Yes. At that point, it was more to study what was happening and to see what the properties of the tissue were and how they would be affected.

Nebeker:

Did you think of yourself as a biomedical engineer?

Welkowitz:

At that time we did not have such a word. It was very clear that our group was unique, as was Schwan’s. I got my Ph.D. in electrical engineering, but for a project I would now call physiology. We were a very mixed group. Since Bill Fry was very oriented to experimental work, there was always biological experimentation going on. I worked on frog muscles, but he and a number of other people, Floyd Dunn and Frank Fry, worked on brain and nerve irradiation on cats, mice, and monkeys. The laboratory maintained monkeys, cats, frogs, and mice. While most people in the laboratory were engineers or physicists, the laboratory was oriented to doing biological experiments.

Nebeker:

Would you say that the lab was biophysics?

Welkowitz:

It was called the “bioacoustics lab” in the electrical engineering department.

Nebeker:

But it was in the EE department?

Welkowitz:

Yes.

Nebeker:

I am just trying to understand where you get some separation between biophysics and bioengineering, historically.

Welkowitz:

Biophysicists then, at least, did more studies of structure of molecules and things like that.

Nebeker:

Not at the systems level?

Welkowitz:

That is correct, not at the systems level. We would be more what biomedical engineers are today. We would be more at the systems level.

### Postdoctoral circular acoustic arrays design, Columbia U.

Nebeker:

You completed your Ph.D. in 1954?

Welkowitz:

Yes. I then spent a year at Columbia University where there was an acoustics lab in the EE Department. I was then approached by a very small company in New Jersey called Gulton Industries, and I spent nine or ten years there.

Nebeker:

Could I ask you about the year at Columbia? What did you do there?

Welkowitz:

I did some work in designing circular acoustic arrays.

Nebeker:

A transmitting array?

Welkowitz:

Yes. Or receiving; since the array was reciprocal. I was able to show that one could design an array without side lobes. This was published in the Journal of the Acoustical Society of America. The analysis holds for electromagnetic antennas also. I did it for point sources of sound.

Nebeker:

Does it have application that you know of?

Welkowitz:

At one time someone in the Navy contacted me, but I do not know what they ever did with it. I think it was being used on a project for studying atmospheric problems, where one could put up an array of microphones around in a circle.

Nebeker:

Was that an analysis you did by hand or by computer?

Welkowitz:

By hand, I used a calculator to do the calculations. The project was interesting because there had been very elaborate analyses of linear arrays of antennas, but to the best of my knowledge, this was one of the first analyzes of circular point source arrays. It had different properties, which was interesting because one cannot make a linear array without side lobes, but you can in this case.

Nebeker:

Where was that work published?

Welkowitz:

In the Journal of the Acoustical Society of America.

Nebeker:

I was wondering if the antenna people might have been interested in that.

Welkowitz:

Yes. It probably would have been better to publish it in an antenna journal.

### Gulton Industries

Nebeker:

Welkowitz:

Gulton Industries at that time, was a very small company that made all kinds of transducers and capacitors. They also made electronic ceramic products. They were expanding at that time and were interested in medical instrumentation.

Nebeker:

What was their previous market?

Welkowitz:

Mostly things like phonograph pickup elements and sonic transducers. They were a major manufacturer of ceramic transducers.

Nebeker:

Is that used in sonar?

Welkowitz:

Yes. When I joined them it was a very small company; I think they had three engineers. It grew to be a fairly sizable company when they shifted into instrumentation.

Nebeker:

Where were they located?

Welkowitz:

They were in Metuchen, New Jersey, and my family moved to Metuchen. We still lived there after I joined Rutgers because it is nearby.

Nebeker:

What did you work on initially there?

Welkowitz:

I started on some medical instruments. I first worked on some catheter instruments.

Nebeker:

Intracardiac catheter microphone?

Welkowitz:

Yes, I designed some of those. One could insert them in a typical cardiac catheter and they were good for locating holes in the heart wall. The sound was localized, and if you moved the microphone around and watched it under a fluoroscope you could see where the sounds were greatest. That led us into making intracardiac pressure gauge. There was always a big interest in intracardiac pressure gauges. People had made some very complex ones using electrodynamic approaches; but required winding hundreds of tiny wires. They were very difficult to construct. We used piezo resistive silicon to make a unit. It was one of the very early ones. People are still using similar designs. This was the first one built in a company and naturally the company patented it.

Nebeker:

I do not want to get into the technology of it, but how do you normally get the pressure reading out of this transducer? I know electric voltage is generated when you subject it to pressure.

Welkowitz:

Under pressure the transducer is bent. It is made something like a phonograph pick up element, with two units. When it is bent one unit is extended and one is reduced. This changes the resistance of each. If one wires them up in a bridge circuit one can obtain an output voltage. Wires run from the catheter to a cable and then to various amplifiers. A diaphragm on one side of the catheter connects the pressure to the bender level. A voltage signal is produced at the output of the bridge circuit. The amount of bending is very small.

Nebeker:

You made both, a microphone to pick up sound and a gage to measure pressure?

Welkowitz:

Yes.

Nebeker:

These were marketed?

Welkowitz:

Yes, they were. As we progressed in this field we started making more and more physiological instrumentation, and that got us into an interesting large project, a physiological monitoring system. By that time Gulton Industries had expanded and had a division in New Mexico which received a large government contract for the Man High project.

Before Nash had people going up in a space capsule they were sending them up in very high balloons and studying the physiological effects. Gulton Industries made the monitoring system. We monitored a dozen physiological parameters packed in a case a foot by a foot by five inches, so that it could be carried aboard and the data recorded.

Nebeker:

It recorded rather than telemetered?

Welkowitz:

Both were done. It was one of the first monitoring systems based upon that work; we got an NIH grant to build one of the first patient monitoring system. Compared to present ones one would call it very crude, but we did have a digital readout. We used a digital printers that generated numbers when fed analog signals. We monitored six parameters including: blood pressure, heart rate, temperature, and breathing. We had previously developed breathing transducers for the Army. We combined transducers with electronics and made two systems for the NIH Clinical Center; one of the earliest patient monitoring systems.

Nebeker:

This is like intensive care monitors?

Welkowitz:

Yes, that is what it was an intensive care monitoring system. Later, that developed into a very large market—which it still is.

Nebeker:

It sounds like Gulton was quite big if it had different divisions?

Welkowitz:

When I first went to Gulton it did a total business a year of a million dollars, and when I left it was between a hundred and two hundred million a year. The company grew quite a bit.

Nebeker:

It sounds like you were building very interesting things at Gulton.

Welkowitz:

Yes.

Nebeker:

Have we covered the most important of those?

Welkowitz:

Yes, at Gulton, I think so.

### Rutgers U., biomedical engineering program in EE Department

Nebeker:

Welkowitz:

Yes. I came to Rutgers.

Nebeker:

Welkowitz:

It came about partially because I decided I wanted to leave Gulton. I had moved up in the organization as the company got bigger, and as I did I realized I was doing less and less technical work and more and more administrative work, and that was not really of interest to me nor my forte. I decided at one point that I was probably better off trying to go back to a university.

Nebeker:

I am impressed that you did so much publication while you were in the industry.

Welkowitz:

It is unusual in a company, but Gulton Industries did not mind it. Some companies do mind it.

Nebeker:

That made it a whole lot easier for you to get a position at a university.

Welkowitz:

Yes. I came here, but I also interviewed with some people at Princeton. At Princeton they had a very sophisticated instrumentation group, but in the Mechanical Engineering Department. I felt I would be a little more comfortable in an Electrical Engineering Department.

Nebeker:

Did you apply for an EE professorship?

Welkowitz:

At Rutgers I got an EE professorship, yes. It occurred at the same time that Rutgers started the medical school that is now the Robert Wood Johnson Medical School. At that time it was the Rutgers Medical School and was part of Rutgers University. I met with the Dean of Engineering and with the Dean of the Medical School and they both felt that my interest was in what we were going to call biomedical engineering. (It was being called that at a number of schools.) I started the program in the electrical engineering department in biomedical engineering.

Nebeker:

You were the first one in the EE Department doing that sort of work?

Welkowitz:

Yes. I actually started with a master’s program here.

Nebeker:

Were most of the early programs graduate programs, masters and Ph.D. programs?

Welkowitz:

Yes, as far as I can remember, they pretty much all were. However, a number of the schools decided to go into undergraduate programs at a fairly early stage. The two most prominent were The University of Pennsylvania and Duke, both of which started undergraduate programs at a fairly early stage.

Nebeker:

You started a master’s program here?

Welkowitz:

Yes.

Nebeker:

You were able to get students?

Welkowitz:

Yes. I had no trouble getting students. It built up slowly, but even during the first year we had three or four students. Initially, those who wanted to go on for a Ph.D. degree were enrolled in EE, but they were really biomedical engineering students. Ultimately, we got permission from the University and the state to give a Ph.D. in biomedical engineering, but we were still in the EE department. At a later date, in 1986, we started this department that you are in.

Nebeker:

It looks like maybe 1987. That is when you became director and chair of the department.

Welkowitz:

Then that would be 1987. Before that I was the chair of Electrical Engineering.

Nebeker:

I see two pretty long stints as EE chair. You did not get away from administration?

Welkowitz:

No. I did when I first came to Rutgers.

Nebeker:

When were you able to hire other people in biomedical engineering?

Welkowitz:

When I first came here there were a few people in electrical engineering who got interested in biomedical engineering and they worked with me. Then when we got a lot of student interest and started getting a lot of graduate students, the University let us hire people in EE who were primarily in biomedical engineering. They formed the nucleus of this department, and they are still here.

Nebeker:

How many positions has it grown to now roughly?

Welkowitz:

I think there are about ten professors. Many places formed departments earlier, although some still have not. Illinois still has a multi-departmental program. There are some administrative and financial advantages to being a department, and the Dean of Engineering suggested we apply to the state to be a Department of Biomedical Engineering. Then it could have a separate budget.

Nebeker:

I would think that there is also this consideration, that biomedical engineering is much bigger than EE in many aspects.

Welkowitz:

Yes. That is another thing that happened with time in all these schools. Originally a large number of the programs were in EE, although the Johns Hopkins one was in the medical school. But the MIT-Harvard one was mostly in EE early on. It spread rapidly to mechanical engineering and, then to the medical school at Harvard. What you saw was that as people started working in different fields, it was clear that it could not just be an electrical engineering activity. In fact, at the present time there is probably much more activity in what you might call chemistry or chemical engineering, with tissue engineering and other similar fields.

Nebeker:

I take it that the current faculty includes people that are doing other types of engineering other than EE?

Welkowitz:

Yes. When we formalized the graduate program here we made sure to include faculty not only from other engineering departments but also from the medical school which was well established by then. The Chair of Surgery, Chair of Pathology Medicine, and Chair of Anesthesiology were always a part of this program. We always had very strong ties to the medical school because it became apparent that if one were going to do something worthwhile, if one carried it far enough, you had to be able to do experimental work. We gave some thought to setting up our own animal lab, but at that time it got very complicated as the rules on animal laboratories and animal keeping are very involved. I did animal experiments for a long time in the department of surgery. I still have a faulty appointment in the surgery department. We used their animals and their animal facilities and it made it much easier than our trying to set up such a facility on our own.

### Biomedical engineering education

Nebeker:

I see you have a couple of early publications on the subject of education in biomedical engineering.

Welkowitz:

Yes. When I first came to Rutgers there were other programs, and there were programs that clearly preceded ours. There was a question of whether this was really an academic field and how one could describe it. It was a strange field. Companies were not very receptive to such graduates. I remember talking to the Hewlett-Packard people because at that time they went into and are still into monitoring, and did a lot of patient monitoring. They told me that they would not hire somebody with a degree in biomedical engineering—they concluded that such a person could not do electronic or mechanical design. They were very skeptical that this was really an academic field. In fact, they tended to discourage schools from starting it as a separate field. They said they would rather hire an electrical engineer and then that person could meet with physicians and pick up medicine and biology while working. It took a long time before people recognized biomedical engineering as an engineering discipline.

Nebeker:

I take it you believe that it is a good idea to have training and the overlapping?

Welkowitz:

Yes. One thing we always did from the beginning of this program was to have the graduate students study biochemistry and physiology. The idea was that if you were going to work in this field, you better know such subject matter. Most students who come from an undergraduate engineering program have never had these courses.

### Computers in medicine

Nebeker:

Another thing I noticed in your publications in the late ‘60s is that you have a couple on the use of computers in medicine.

Welkowitz:

Yes. When we first came here, one of the hospitals, Perth Amboy Hospital, had an interesting person in charge of pathology. For a localized hospital, that was unusual. He wanted very much to computerize the pathology laboratory, both for the chemical testing and the general record keeping. A couple of us agreed to work with him. We worked with them and, while we did not design the computers, we sat in on all their meetings and, in fact, worked with them to set up systems. Considering that they are a small local hospital, Dr. Pribor had some of the earliest systems that took the data from the analytical instruments and directly fed them into a computer and then printed them out into a format where they could be used for diagnosis very easily. You could get all that information by going around to each piece of equipment and writing down the numbers. It turns out there are many big advantages in computer memory.

Nebeker:

Was the idea that not only the gathering of the information, but the record keeping would be in computer memory?

Welkowitz:

Yes, the entire record keeping was in the computer. The Pathologists set up coding for every patient and the tests that were done, then the computer fed a printer that printed out labels for the blood drawing. The whole thing was pretty well automated at that time. After the original work some specialized computer companies were providing standard equipment for this, but not at the start.

### Control systems of heart-assisted devices

Nebeker:

There is another interesting area that you have worked in. I noticed you had some work on the control systems of heart-assisted devices.

Welkowitz:

Yes, I worked on that with Dr. Kantrowitz’s group. That is where I first worked with Dov Jaron. At that time there were a few groups in the country who were experimenting with heart transplants, and with the other schemes in case there were not enough hearts for transplants. That is still a problem for heart transplants. There was some work going on with mechanical assist devices and total heart replacements. I met with Dr. Kantrowitz, who was doing work on assist devices. Our group at Rutgers then became a subgroup the engineering part of his very large grants from NIH. He also wanted to hire some more people. He had one engineer that worked with him but when he wanted to enlarge his group, I helped interview the people and he hired Dov Jaron. Don had his Ph.D. from the University of Pennsylvania, and I recommended that they pick him. They did, and he became the senior engineer in the group. We worked a lot through him since this was a joint activity. At first Kantrowitz’s group did a lot of animal experiments and finally they worked with patients. The original assists devices were balloon pumps, which are now standard products to assist the heart after surgery. We did a lot of analysis of optimal control settings.

Nebeker:

You were working as a consultant on this?

Welkowitz:

No. We actually had a group here at Rutgers and the University had a subcontract from the NIH grant.

Nebeker:

Dov Jaron was not part of this group here?

Welkowitz:

No, he was part of Kantrowitz’s group. At that point Kantrowitz had some engineering with whom we could talk more readily, and it worked well for many years. Kantrowitz was originally in Brooklyn, but then he moved out to Detroit and we kept working with him there. We actually built equipment to drive the balloon pumps using some algorithms that we felt were optimal or reasonably optimal. We studied this whole problem and we had a number of people do Ph.D. theses on what is optimal assistance. It is not an easy problem. This work led to the possibility of controlling a total artificial heart. Kantrowitz, while we were connected with his group, eventually put it into a patient an assist that got sewn into the aorta. It worked like a balloon pump, only permanently inserted. It had tubes brought out through the skin, an air supply to inflate it, and electrical leads to drive the control system. We designed the control equipment here at Rutgers, and at a very early date it was used on patients. Some of these were on the system for months.

Nebeker:

Was the control of the balloon pump automatic?

Welkowitz:

Eventually, yes. Originally it had mechanical settings.

Nebeker:

You would look at the electrocardiogram and adjust?

Welkowitz:

Blood pressure waveforms were the prime ones to look at.

Nebeker:

Was it an objective from the beginning that this should be fully automatic?

Welkowitz:

Yes.

Nebeker:

But that took some time to achieve?

Welkowitz:

That took some time. Kantrowitz actually spearheaded the clinical acceptance all over the country. He formed a group of twenty major hospitals around the country. They all had the same equipment (designed at Rutgers) and assisted patients, they came to an agreement on the results and proved that the results were beneficial. At that point balloon pumping mushroomed as a business.

Nebeker:

Do you think that is an example of what, at least in the commercial realm, is called the product champion—somebody who really pushed the technique?

Welkowitz:

Yes. I do not know if it would have ever gone anywhere without him. There were always people very negative about it who said, “This is silly and it is not going to do anything. Forget it.” He stuck with it. He was the one who got it off the ground. It took a lot of work to get support of a twenty-hospital group that all did the same experiments. They set up a common protocol. They studied for about a year, and therefore had a very large patient group that they had studied and that established balloon pumping as a useful process. We made twenty driving systems at Rutgers; something which we were not accustomed to doing.

Nebeker:

Because there was no manufacturer out there?

Welkowitz:

We had a company do parts of it for us, and then we did all the final set-ups here. It was a little odd because a University is not particularly well set up to do this. Students do not like to do repetitive work.

Nebeker:

And assemble equipment.

Welkowitz:

Yes. But it worked out very well.

### Commercial development and bioinstrumentation

Nebeker:

Were you ever subsequently interested yourself into going into business?

Welkowitz:

No. I had been in a company and realized I could rise in a company, but I felt then and later on that I did not want to be in a job where I was mainly in administration.

Nebeker:

I could imagine that maybe some things you had been working on that you saw an opportunity to commercialize.

Welkowitz:

At various times we did, but it was difficult. It turns out somebody had to push commercial development. If you are a professor, you often do not like to do that. We had contacts with some businesses on some of the other products we developed. A number of times we did joint experiments with them. Even that was a little difficult because you then had to get students who could fit in with some schedule at a hospital. We had to get a group of students to do this because sometimes they had classes when the hospital wanted to study a patient. It was not easy to work with a company unless you really wanted to dedicate yourself to it. I think if we had done that, we could have done more in the product development area, but that is difficult unless your interests happen to lie in product development. In that case you would probably go to work for a company.

Nebeker:

Was it the overall story in bioinstrumentation and these other devices? Have there been a huge number of these startups that have succeeded?

Welkowitz:

Yes.

Nebeker:

As opposed to some big established company coming in.

Welkowitz:

The big established companies often do better because of the complex FDA approvals needed. They have corporate-wide people who work with the FDA or any other group, and they know what has to be done to carry a product through for approval. Now all medical instruments have to go through FDA approval. Small companies have more problems with that. We worked with such a company.

Nebeker:

Welkowitz:

A small company in the area.

Nebeker:

One of the Rutgers students?

Welkowitz:

No. This company found that FDA approval was getting more complicated. Finally I understand it hired somebody just to interface with various government agencies and make sure all the things they wanted were being done. It meant that if we wanted to push a product, we would have had to get some people here interested in that aspect of products. It is very hard to do at a university.

Nebeker:

I was thinking more of the question of how easy it is to be a startup in this field. In software, for example, it is probably a lot easier to put out some new product.

Welkowitz:

I do not think it is hard to do it in medical instruments either, except that the hardest part is probably getting the approval. Building a prototype is fairly easy, assuming the person starting up is clever at this sort of thing.

### Regulation of clinical research

Nebeker:

And it is a good idea. Generally speaking, do you think that there are too many constraints on experimentation and clinical research in this country?

Welkowitz:

I do not think so, because I think people not careful enough with patients before these regulations were enacted. On the other hand, doing patient studies with instruments is a slow process because everything has to meet the appropriate standards and get written approval. You cannot do it in a hurry.

### Books on medical instrument design, hemodynamics

Nebeker:

I wanted to ask you about the general book on biomedical instruments you have written.

Welkowitz:

Yes. It is published by the Academic Press. I used it originally to teach from. I do not know what is used now, but for twenty years I used that material.

Nebeker:

Yes. You collaborated with Sid Deutsch.

Welkowitz:

Sid Deutsch, yes.

Nebeker:

How did you feel about taking the time from research to write a general treatment of medical instrument design?

Welkowitz:

At the time I wrote it, I wrote two books, and they each have gone into a second edition. Rutgers University Research Council supported me for a year with pay to write these two books. The other one is on hemodynamics.

Nebeker:

A year’s leave to write two books? Pretty ambitious year.

Welkowitz:

Actually, it worked out well. Everybody told me that sitting and writing a book for eight hours a day is tedious. I was good at starting early in the morning, and working at one of them until lunchtime, then I would put it away and I would work at the other one in the afternoon. I would do this five days a week. I did it at home as if I were coming into work. The reason I did it at home is that one gets too many interruptions at work, so I just stayed home and then both books were written in a year.

Nebeker:

They seem to have been well received; as you say they have gone into second editions.

Welkowitz:

Yes. The second edition of the instrument book that one is by Academic Press, and the second edition of the other one was by NYU Press. Some years ago NYU Press was interested in books on biomedical engineering, and I edited a series of eight books for them

Nebeker:

I am curious about the title Engineering Hemodynamics. Isn’t hemodynamics a branch of physiology?

Welkowitz:

Yes. A lot of the work I did, both on assisted circulation and diagnosis were related to blood flow. Actually, a lot of my research here at Rutgers was on blood flow.

Nebeker:

It seems like a lot of this is straight physiology.

Welkowitz:

Some of it is. Interestingly, after we got different results from what were accepted in physiology, but what we tried to do is look at this complex system and study it as a mechanics problem with flowing fluids in a bifurcating type system. It turned out that some of the more accepted concepts in physiology were probably not correct—physiologists never analyzed the system that way. There have been other engineering people who analyzed it and came to the same conclusions that we did. For example, the aorta tapers both geometrically and, interestingly, in its elasticity. The amount of elastin in the walls varies. It turns out most people said that many of the waveforms observed are just due to reflections of the end of this line. We showed that you could get the same waveforms with no reflections. If you analyze the taper carefully, you find that tapered systems have this property. Why is the system tapered and why isn’t it a nice uniform tube? It isn’t. I suspect the reason it tapers this way is to match impedances, so you get the pulsatils flow flowing out more easily. This is the sort of information you get only if you do an engineering analysis. If you were a traditional physiologist and you made waveform measurements (which they do, and make some very good ones) you might look at them and say, “Why does the input look one way and the output look different?” You might say, “Somebody told me that there is such a thing as reflection so maybe that is what is doing it.” That is a typical traditional physiological approach to that problem, after doing very good pressure measurements. They do not do engineering analysis and they come up with an explanation that may or may not make sense. We engineers try to approach the problem differently. Suppose we say that their approach is not what occurs. What would happen if this were a nicely matched system with? Would this difference in waveforms occur? What I show in my book is that they match up very well with this concept, rather than with a concept that does not match the anatomy. Their approach would match if these were uniform systems. One realizes that there are many things in the body that are well designed, but nobody gives much thought to why they are designed that way. What purpose does it serve to have a tapered aorta? Why is it that way? My suspicion is that it is that way so that there is a much better pulsatil flow transmission.

Nebeker:

One could have a very accurate descriptive physiology of the dynamics of blood flow and not have any understanding of why the system has the parameters it does. By taking the engineer’s approach of how to achieve different effects, you could better understand the system. Is that the idea?

Welkowitz:

That is correct. In fact, it was a big help when we did the work with Kantrowitz on the balloon pump. We analyzed the system as an engineering system, worked out everything, and were able to show that there were optimum adjustments for the balloon pump timing. The original investigators were not very careful how they adjusted the timing. They did not think that it was particularly important.

Nebeker:

That sounds like it might be an impossible thing to quantify optimally.

Welkowitz:

It turns out it requires a complicated system, but it is not impossible. If I want to get the lightest load say on a sick heart, how would I adjust the system? You can calculate the loads and vary some of the parameters, for example the timing of the balloon inflation and deflation, and you can show analytically that there is an optimum. The optimum is what you should set the system at.

### The engineer's approach to physiology

Nebeker:

How much of this engineering approach is simply computer modeling? If you have a computer model that is adequate then you can do these things.

Welkowitz:

A certain amount is. We did computer modeling of the system, and yes you can do it well. If you just do computer modeling empirically, you do not learn about the system.

Nebeker:

Understanding what is going on.

Welkowitz:

If you work out the equations and look at what is important in them, you probably will learn more of the physiology. In other words, what is important in the physiological systems. I worked for a while on blood vessels. Why are they elastic at all? Why aren’t they rigid? Actually it was one of the early things we studied. We got some data from a colleague of mine who measured the elastic constants of rings cut out all along the aorta and showed that they had different elasticity’s. You say to yourself, “Why? Does this serve any function? It must serve some kind of function.”

Nebeker:

It is also interesting that someone would investigate that. You might just take for granted that there is a kind of elasticity.

Welkowitz:

We use pipes in houses and we always make them rigid. Are elastic ones better or worse?

Nebeker:

It’s that raising the issue.

Welkowitz:

Why is it that way? One thing we learned from some of the equation approaches rather than straight modeling (although we have done straight modeling too) is to better understand the physiology? I think as physiology is progressing, one needs more of that—there is some advantage to understanding why things are the way they are. My suspicion is that the only way people will learn how the brain works in any great detail will be to analyze this exceedingly large system. We do not have good ways of handling such a large system.

Nebeker:

So this is engineering resulting in physiology—better understanding of the body.

Welkowitz:

Yes, better understanding of the body.

Nebeker:

Of course, it has applications if you are trying to do cardiac assists, as you have worked on.

Welkowitz:

Yes. It is like many other basic things you study and then find that there is some practical use for them.

### Research highlights

Nebeker:

Point out some of the highlights with your research in the ‘70s. You have a long list of publications, for example the indices of Cardiac Status.

Welkowitz:

That again came from similar work. A lot of it is in the hemodynamics book. I did the paper during a year when I was in Hawaii on a leave. I knew people in the physiology department and I had a lot of time to go to the library. Medical people use certain indices for diagnosis, some of which are easy to measure and some of which are difficult. There is a question of whether certain other indices might be more useful, these may be as easy to measure, or sometimes easier. I looked at a lot of the possible indices that relate to diseases of the heart, to see whether one could do a more quantitative type diagnosis, especially if one is at all interested in automated diagnosis. In much of the diagnosis now, a physician uses a lot of memory, thought, and experience. It is not easy to automate anything like that.

Nebeker:

I am sure a lot of the evidence is non-numerical. It is images of some sort, or maybe something visual.

Welkowitz:

Yes.

This article was an attempt in the cardiovascular system—the heart, really—to find some things that had some rationale from an engineering point of view. These might tell you something about the tissue, or an infarct or the electrical activation, which could be measured. One could then analytically show what was related to things you would like to know. I wrote this paper on that and it was one of the more popular papers I ever wrote. I got about 500 requests for reprints.

Nebeker:

I can imagine with more and more engineer devices being used in medical diagnosis, treatment, and even implanted devices, it is more and more important to have quantitative measures of the information about the body.

Welkowitz:

Yes. I think that is where biomedical engineering can serve a very good purpose. One would have to do enough engineering analysis of the body to put these measures on some kind of physical basis. Consider the blood flow problem. Engineers have been analyzing flows in elastic systems for a long time and there is a lot of engineering knowledge that could be applied to this problem. One could better understand what the measurements mean, and what measurements are needed to help find defects in the system. Right now I think people are beginning to do this. The history in medicine was that certain measurements were convenient to make, and then there were attempts to diagnose from those measurements. A very interesting history was of ballisto-cardiographs. If you lie on a table and put a bar across your legs and put an accelerometer (an instrument that measures acceleration) across your legs, your body will shake when your heartbeats, and one can record this acceleration measurement. In the ‘60s this was a very popular measurement in cardiology groups in hospitals because the waveform could be analyzed in a way similar to electrocardiograms. A whole diagnostic system was developed. There are books on ballisto-cardiography. This looked interesting, but again, it was very empirical.

Then someone did an engineering analysis of the system and discovered that ninety percent of the waveform was due to the fact that the heart is a mass hanging on ligatures. It is a spring and mass system with some anomalies. Most of the observed changes were second order effects that could obviously be changed by noise or by how rigid the table was. Ballisto-cardiography then fell into disfavor because it was clear that the waveform changes being used were really not things that were major. If there were an imperfection in the heart, or in its weight, one could get a different waveform. Cardiologists then realized that Ballisto-cardiography was really not a legitimate diagnosis tool.

Electrocardiography started out the same way. It is a very old field. People measured waveforms and qualified similarities in size and shapes. A standard electrocardiography book shows you all of the things in the waveforms that you can use in diagnosis. It took quite a number of years before people recognized that, first of all, a lot of this depended on where on the body you put the electrodes. There was a very big shift in this about twenty years ago. The old standard was to put electrodes on the arms and legs around the ankles and wrists. One of the leg electrodes was used as a reference and the other three were the active ones. Those were the waveforms that one studied. Investigators looked into the ECG problem as a problem of electrical sources in a cylinder. They pointed out that to study the heart one would be better off putting the electrodes around the chest and back—in the area where the heart is—rather than at the extremities because those locations yield the worst results. A full body electrocardiogram yields more information. They also discovered that the most useful information from wrist electrodes is the heart rate. It is very important to know the rate, but that is a poor place to measure it. It was not until someone analyzed this problem as an engineering problem that one realized that the wrist was a poor place to measure. One may as well measure in a good place and get more information.

Nebeker:

In physics there were all these empirical measurements of spectrum, and then quantum mechanics was able to explain that it was due to these jumps and electrons. Has this happened with electrocardiograms, and can one actually explain the model of the heart that account for these?

Welkowitz:

Yes. It is a very difficult problem but there have been some solutions. One would like to do what is called inverse electrocardiography. Let us assume that you make twelve electrode measurements around the body. Can you then describe the electrical source as an inversion problem? It turns out that this is a very difficult mathematical problem. People have made some headway, especially with computers, in solving the inverse problem. A solution will give you much more knowledge of the electrical activity of the heart. If you make some assumptions about heart shape or even use a real heart shape, you might be able to tell, for example, where defects are and if they are not being electrically excited. A number of medical inverse problems that you would like to solve are difficult. The best results came from the imaging systems such as CAT scans and MRI’s where people solved the inverse problem. Using external measurements there is a mathematical procedure to get the inverse so one can actually see the image of an inside structure from the outside measurements. That success created much interest in inverse problems. That technique is one of the major successes of biomedical engineering.

### Influential developments in medical instrumentation

Nebeker:

Since you have written about medical instrumentation generally, could you comment on what developments over the last decades have really had major consequences?

Welkowitz:

There is no question that far above everything else was the development of imaging systems. Thirty years ago the only way of looking inside the body was with an x-ray. That produced a crude picture because it was a summation of all the absorptions through the body. Bone is more absorbing than other tissue so one mostly saw bone. Many tissues are not very absorbing and you do not see them at all. Also, if there is a bone in front of another structure you cannot see what is behind it.

Hounsfield, at EMI, got a Nobel Prize for solving this inverse problem and building a piece of equipment. He was the first one to build a commercially successful CAT scan system. It could easily be used in hospitals. The technique utilized mathematics and physics that was developed to look at the structure of the inside of the sun. Essentially MRI’s use the same inverse system.

Nebeker:

So these imaging systems have had a tremendous impact.

Welkowitz:

There is no question that in engineering in medicine they are far and away the most important developments.

Nebeker:

Ultrasound imaging being included?

Welkowitz:

Yes. Most places that do imaging now do all imaging. MRI systems and CAT scans do the most sophisticated analysis, and do it successfully.

Another major development was implantable cardiac pacemakers. There are millions of people with implanted pacemakers now. Implantable pacemakers were first invented by Greatbatch and his designs were very successful, especially now that units have switched to lithium ion batteries so that one does not have to change the battery pack every few years. When they are used on older people, one unit will probably last the rest of the person’s life. That is interesting because, in a sense, it becomes an implantable organ with general acceptance. Its use is an accepted medical procedure.

Nebeker:

What about in the area of monitoring?

Welkowitz:

Monitoring has developed very well. You were mentioning intensive care monitoring. The systems now are very good. They are elaborate and they measure many things. They are all computerized now and use automatic alarms.

Nebeker:

That is no doubt important.

Welkowitz:

With a patient in an intensive care unit, it is pretty clear that if anything untoward develops, somebody will be alerted quickly.

Nebeker:

Are there new types of transducers or new types of measurements being made in intensive care that were not there thirty years ago?

Welkowitz:

Yes. They are more sophisticated. One development that is still needed is cardiac output non-invasively. Physicians do measure cardiac output with a swan-ganz catheter and a pressure gauge. That is not as invasive as opening the chest one must put a catheter in the patient. This system is used with almost all cardiac intensive care patients.

While blood pressure is commonly measured, what you want to know most about the heart is the cardiac output—how much blood is it pumping out.

The whole area of non-invasive instruments is very important. If one could make instruments, with the same measurement but on the outside of the body it would greatly help monitoring. We looked into the area of measuring cardiac external measurements. Internal measurements, even with catheters, have a certain amount of danger. Catheterization, while it is common, has something like a one percent or two percent damage rate where people get into trouble from cardiac catheters. That is why it is only done in hospitals that can do open-heart surgery.

Nebeker:

What about catheter instrumentation itself? Has miniaturization done a lot?

Welkowitz:

One can put small instruments all over the body now. There is a lot of work being done on that, and we did a lot of the early work with the pressure and sound measurements. One can make blood gas measurements that way. I think that work will continue. However, totally external measurements are still more desirable.

Nebeker:

Maybe the capability of computers with adequate models combined with all the external measurements will allow that kind of diagnosis.

Welkowitz:

Yes.

Nebeker:

What other things haven’t we mentioned?

Welkowitz:

I think we have mentioned most everything. Our recent work has been in non-invasive instrumentation, measuring cardiac output and measuring coronary artery occlusion non-invasively. Those are the areas that are most up to date, and I think they are still areas that require much research. They are quite interesting.

### IRE, IEEE, and societies

Nebeker:

I wonder if I could ask a couple of questions about the professional societies in the field? You have been an IEEE member for a long time, I take it?

Welkowitz:

Yes.

Nebeker:

For me coming into this for the first time, it is bewildering with all of these different societies out there, the more specialized ones such as the ultrasound people, then there are four or five that seem to be the same thing.

Welkowitz:

There is a heavy overlap. One of the first groups was Engineering in Medicine and Biology Society of the IEEE. That was formed because there was a sizable number of interest people and they decided to have meetings annually. When IEEE decided to break into thirty or forty societies it became one the societies. It was very easy to say this was a field where we get together. There had been annual meetings even before that society was formed because there was much interest in these problems all around the world.

Nebeker:

Were you a student member of the IRE Radio Engineers in the late ‘40s or early ‘50s?

Welkowitz:

Yes.

Nebeker:

Were you aware of the professional group, Medical Electronics and Nucleonics?

Welkowitz:

Yes.

Nebeker:

You were a member of that?

Welkowitz:

Yes.

Nebeker:

As you say, there was an annual meeting that proceeded the formation of EMBS.

Welkowitz:

Yes.

Nebeker:

Herman Schwan was telling me about that. You remained an IEEE member because that society or professional group was formed?

Welkowitz:

Yes, ever since I was a student member.

Nebeker:

What other professional groups have you been part of?

Welkowitz:

There is another large biomedical engineering group, the BMES. I think I know why that started. There were a large number of people working in the field who were mechanical and chemical engineers, and they always felt that a group under the IEEE did not give them enough prominence. When I worked on artificial hearts and heart assist devices, I became a member of the American Society of Artificial Internal Organs, and for a while I was also a member of the International Society of Artificial and Internal Organs. They were interesting because they were mixed medical and engineering groups.

Nebeker:

The IEEE’s society is mainly of engineers.

Welkowitz:

Yes, they take in medical people if they want to be members, but it is clear that this is an engineering group.

Nebeker:

There was one that you were a founding member of that started in 1992, The American Institute of Medical and Biological Engineering.

Welkowitz:

The reason that started was that even IEEE had a very limited impact on government agencies. I do not know what the history was. At one time when I was very active in IEEE, we visited Congressmen to try to influence policy. AIMBE was founded primarily to interact with the government and to affect government policy. The simplest example is NIH which has many institutions but does not have a biomedical engineering institute. It has a number of biomedical engineering laboratories, some of which are quite good, but there is no institute. In fact, over the years starting such an institute was proposed many times to NIH and it was not accepted. AIMBE has made real progress recently in getting congress behind such an institute. It would combine biomedical engineering with imaging.

AIMBE is really an organization set up to do lobbying for biomedical engineering. I think it has been quite successful.

Nebeker:

The combined institute is probably easier to sell in the medical community.

Welkowitz:

Yes it is. I am also a fellow of the New York Academy of Medicine. It resulted from my cardiological work. The Academy of Medicine is very much a medicine group. I am a member of the New York Academy of Science, which is a mixed group. At one time it had a subgroup on medical instruments, but there were not enough members to support it. Now there is a general instrumentation area that sometimes has lectures on medical instruments.

### Medical professionals' engagement with biomedical engineering research

Nebeker:

At the beginning of your career biomedical engineering was hardly a recognized field, but there were people doing that work. Have you seen a real change in the way the field is perceived by the medical profession?

Welkowitz:

Yes. Again, I would say a lot of that has to do with the imaging developments. There is no question that most physicians now accept these very complex imaging systems as being the proper way to examine patients. Some of the younger ones do not even understand how anyone ever diagnosed disorders without this. I think medical people now fully accept imaging as providing them with necessary information. Now they say, “Maybe engineering has something to offer.”

Nebeker:

Do you think if there had not been this visual output, if we were talking about impedance measurements or something like that, it would be a harder sell?

Welkowitz:

A much harder sell. With imaging they get a picture now that they recognize as something they see in surgery or that they saw in medical school. If you slice across the head and you look at the skull and the brain, some of the pictures I have seen look just like the actual anatomy. I think physicians can understand imaging much better than other measurements. This is something they always wanted to see the image, and now they can see it without cutting the patient in half. I think this has led to a much better appreciation of engineering in medicine. Physicians that do cancer treatment with focused radiations and neutron bombardment recognize that these pieces of equipment are doing something very positive for their patients. Cardiologists would not know what to do without pacemakers.

Nebeker:

I am also thinking that it changes their attitude toward the engineering.

Welkowitz:

Yes, because they know these are engineering devices. They recognize that these devices are helping them do better medicine. For a long time this was not true.

Nebeker:

I have also heard from Thelma Estrin that an electronics engineer, even if she or he had a Ph.D., was seen the way a technician was seen.

Welkowitz:

Yes.

Nebeker:

Here is a doctor, the one that has all the knowledge, and you are able to do some little thing with some box.

Welkowitz:

Yes, I think Thelma is correct. The original feeling about biomedical engineers was that maybe they could fix some of the broken equipment. Many community colleges have programs for biomedical engineering technicians, and I was involved many years ago in setting some up for New York State. It was hard to tell the doctors that a biomedical engineer was not a biomedical engineering technician or vice versa. I think there is now a much better acceptance of this field. I am sure Thelma had many ideas about that. When she first went into medical computer work, there were a lot of people who probably did not accept her.

Nebeker:

Thank you very much. I have taken a lot of your time.

Welkowitz:

You are very welcome.