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David Hadley

David Hadley

Senior Vice President of Research and Development, Cardiac Insight

By David Zierler, Director of the Caltech Heritage Project
April 13, 2022

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Wednesday, April 13, 2022. I am delighted to be here with Dr. David Hadley. Dave, great to be with you. Thank you for joining me today.

DAVID HADLEY: Thanks, David. It's a pleasure.

ZIERLER: To start, would you tell me your title and affiliations?

HADLEY: I'm Senior Vice President for Research and Development with a company called Cardiac Insight. We provide medical devices for monitoring electrical activities in the heart, primarily for detection of atrial fibrillation, but also for other cardiomyopathies.

ZIERLER: The big and obvious question. Intellectually and scientifically, what is the connection between cardiac science and your education and early career in seismology?

HADLEY: Great question. Waves in the earth are, of course, very well understood, clear physical phenomena with good mathematical descriptions. And it turns out that waves in the heart are really well-represented by a rotating electrical dipole, and the signals have a lot of similarity to those of an earthquake. We even have some of the same names, we have P-waves, QRS-waves, and T-waves instead of the usual P-, S-, R-, and L-waves in seismology. Growing up at the Seismo Lab and doing large-scale computing, looking at strong ground motion and earth structures, our skills were honed around digital signal processing, waveform analysis, large-scale databasing. Those have all proven to be extremely useful in cardio. And I think some of the inversion techniques and data analysis techniques are, or were when I came into this business, new to the cardiac field and have been quite useful. I actually felt quite at home in cardiology. [Laugh]

ZIERLER: It's not obvious to see connections between biology and geophysics. More deeply, what does that tell us about instrumentation, observation, and theory, where you have drawn all of these connections?

HADLEY: I think Caltech teaches you how to think, how to reason, and provides the basis for you to jump into new fields, use what you've learned in the past, and apply those learnings to understanding and growing into a new area. I think when I was at Caltech, the thing that impressed me most was the cross-fertilization. The physicists that walk across campus and sits down with the biologist or the chemist. I think that process is where magic happens, new insights in both directions. I think that's certainly been true in my career. I've really enjoyed exploring a new area, but also bringing forward the tools and experiences gained from before.

ZIERLER: At what point in your career did you make the transition from geophysics and seismology to cardiac science?

HADLEY: Bob Hart and I started our first company while we were still at the Lab. I was finishing my PhD, and Bob was a fellow. We started a company in geophysics called Sierra Geophysics. Grew that up. We found that the work we were doing for Department of Defense for nuclear detection and discrimination and strong ground motions for Southern California Edison, all that work developing tools for wave propagation studies were suddenly very interesting to the oil and gas industry. We retuned the company and started focusing on products to aid oil and gas exploration. We grew that company up, ultimately sold it, then I worked with a small startup that was almost a pure knowledge-based enterprise interested in trying to capture knowledge in the workflow, then trying to form that into some useful information for large-scale customer support organizations. A pure knowledge play, if you will. Quite interesting, a lot of fun. I was recruited in the 90s to come in and manage a turnaround situation in a diagnostic cardiology company, a group that had grown out of UW Medicine many years ago that had gone through several owners. It was a turnaround, and I was brought in to rebuild the engineering team and a suite of products. I've been doing that kind of work for quite a while, and I felt comfortable coming into the cardiology group. I didn't know much about the heart, but I knew how to organize teams and build products. And I fell in love with cardiology. I found my experiences were useful, and I've been doing that ever since.

ZIERLER: To go back to your education now, in the early 1970s, when you were at UC Riverside, were you interested in geophysics and seismology even at that point?

HADLEY: I finished an undergraduate bachelor's in physics, and that was in 1971. I started graduate school in physics, but in the early 70s, the jobs in physics were tough to find. It was a bit depressing. I was kind of casting about on where I could find a job and enjoy it. I wandered over to the geology building and met a professor there, Shawn Biehler and he sucked me in. I finished a master's there, then Shawn sent me over to the Seismo Lab.

ZIERLER: What was Shawn working on at that point?

HADLEY: Shawn 's always been interested in gravity studies. There's an interesting story, if I might digress. Shawn was part of the group back in the mid-60s at the Seismo Lab with Don Anderson, Harkrider, back when Frank Press was running the Lab. About the time Shawn graduated, Frank moved MIT. Frank took Shawn back to MIT, and a young student, Bob Hart, in astronomy happened to wander into the building who'd been casting about and met Shawn. Shawn sucked him into geophysics back there. Subsequently Bob was recruited to come out to Caltech. Shawn was then recruited to be a professor at UC Riverside, which is where I met him. When I finished my master's, Shawn sent me off to the Seismo Lab. Both Bob and I were heavily influenced by Shawn, going all the way back to the mid-60s. Kind of amusing, we started a company together and have been close, fast friends ever since. My daughter married Bob's nephew, so it's been a long, prosperous, fun, loving relationship.

ZIERLER: What were your impressions when you first arrived at the Seismo Lab? Had it moved to South Mudd already, or was it still at the old campus?

HADLEY: No, I had one year at the old lab, and it was magical. For years, I saw programs on earthquakes in Southern California, seeing Clarence Allan talking about earthquakes, and I always thought that'd be something really fun. Then, to be able to work with Clarence was awesome, really great. He was a very inspiring guy, very encouraging, helpful. I remember when I got there, I was assigned to be his research assistant, so I asked him, "What would you like me to do?" He looked dumbfounded and was sort of like, "Go do what you want to do." [Laugh] Being at the old Seismo Lab, there was a lot of camaraderie. The close and cluttered environment I think was conducive to building friendships and a lot of cross-discipline work with each other. And the legendary coffees were held down in the basement in the old furnace room, so it was hard to escape being close and friendly. But it was a great place. I think we all loved being there.

ZIERLER: Did you know that the Lab was in the process of moving to campus already?

HADLEY: I'm not sure if I did. Obviously, we learned that fairly soon, but I'm not sure I knew that when I first got to the old mansion.

ZIERLER: Do you have a sense from faculty, more senior people in the Lab, what the impetus was to move to campus?

HADLEY: No, I really don't. I think it was a desire to have all the geology and geophysics students together. I think there were probably some economic issues associated with the move, the need for more space. We wanted to stay on the hill, but that was not to be. [Laugh]

ZIERLER: Did you help with packing up the mansion and moving to campus? What did that endeavor look like?

HADLEY: I think all of us were responsible for moving all of our personal office stuff. Movers moved whatever furniture they could or what they decided to keep. There was a lot of new furniture when we moved into Mudd. It wasn't a big deal. I think it was over the summer.

ZIERLER: Was it an opportunity to get rid of old equipment in favor of new equipment? Or did everybody want all the old stuff to come along, too?

HADLEY: I think most of the old stuff came along. When I got to the Lab, I was stunned. There was an old vacuum tube computer that ran on a paper tape, and that was what was still being used for locating earthquakes in Southern California. And that came down to the new lab, and I think it was still used for a year or so until it was completely replaced with more modern things. But modern back was still primitive by today's standards. The computer I mostly used only had 64K bytes memory. I was given a 10-inch disk that would hold five megabytes, and I couldn't imagine how I would ever fill five megabytes of data. [Laugh] Things have changed.

ZIERLER: What were the big debates at the Seismo Lab when you first arrived, both on the theory side and the observation side? What were people really working on and debating at that point?

HADLEY: I think everybody thinks their time was always special, but plate tectonics was just really emerging. A couple years before I got there, a graduate student presented his one-year oral exam on plate tectonics, and they threw him out. They just didn't believe that that was possible. It was a real sea change, that plate tectonics was real and explained a lot of phenomena. It was a golden time in geophysics, a lot of discoveries, a lot of new insights. It was just a great time to be there.

ZIERLER: What was the process for you choosing an advisor and a thesis topic?

HADLEY: When I got there, Clarence was my academic advisor. I had done, at UC Riverside, some earthquake monitoring in the San Bernardino Valley, some down in Imperial Valley. Shawn Biehler led summer field courses and classes in field geophysics, so I'd done seismic, gravity, and magnetic surveys in Southern California. I had a lot of interest in the structure and tectonics of Southern California. When I got to the Lab, that was my interest, and I was quite interested in the small-but-growing seismic stations in Southern California, what research could be done. There was a lot of interest at that time in earthquake prediction. I spent probably my first two years looking at travel times from quarry blasts to stations all over Southern California. I finally decided nature wasn't going to give up that answer easily, so I moved on from earthquake prediction to looking more at geology, geophysics, and structure of Southern California. I found working with Hiroo Kanamori to be very rewarding. Super great guy.

ZIERLER: Did Hiroo end up being your advisor?

HADLEY: Yeah, he did.

ZIERLER: What was the transition like from Clarence to Hiroo? How did that play out?

HADLEY: There was almost no transition. Clarence was my academic advisor, but at the Lab, you were pretty free to work with whoever you wanted. I did a paper with Helmberger, worked with Harkrider, and with several fellow graduate students. It was pretty fluid, and I don't recall any issue at all.

ZIERLER: What was Hiroo's research at that point? What was he working on?

HADLEY: Hiroo and Don Anderson were really focused on large earthquakes. That has been and continues to be Hiroo's love. When I visited him just recently, he was still pulling out seismograms and showing me records of great earthquakes around the world. That's what he loves to do. But he's been a great coach for a lot of graduate students, and I certainly benefitted by spending time with him.

ZIERLER: From that early optimism on earthquake prediction, what did you learn? What was the takeaway from that in terms of expectations, limitations in theory and observations? What did you take away from that experience?

HADLEY: The earth is a lot more complicated than it is in the lab. [Laugh] The things that seemed clear and reproducible in the lab, in a heterogeneous, complex earth don't always hold up very well. I think it's probably pretty obvious, but I think a lot of us struggled for a while without realizing what a tough problem it was.

ZIERLER: Switching gears, to what extent was Hiroo providing guidance and mentorship on how you should work on next topics for what ultimately would become your thesis?

HADLEY: Probably most of it happened around coffee in the old lab. You'd have some idea or some new piece of data, you'd bring it to coffee, it'd get kicked around, you'd try things, bring it back, have a conversation. I don't recall Hiroo saying, "Hey, you need to go do this." It wasn't a directive. It was, "There are a lot of opportunities and interesting data. Use your curiosity and go find stuff." I think the lab has also been super productive simply because of the vast amount of data we had access to. I'm not a theoretician, I'm not like Dave Harkrider who was doing theory. I'm more on the applied, practical side of, "Let's look at the data and see what we can learn about the earth and how it works."

ZIERLER: Looking at the data, not being a theoretician, what were some of the theories that were important or at least provided guidance for how to interpret the data at that point?

HADLEY: I was particularly interested in the structure of Southern California, particularly around what we call the Transverse Ranges, why the San Gabriel and San Bernardino Mountains straddle structures that all more or less trend north-northwest when here we have this east-west feature cutting right across all of that. And that always struck me as kind of strange. Why was that there? The gravity and seismic data indicated that although most mountains have some kind of root that thickens the crust, but the San Gabriels seemed to have no root. Why is it not isostatically compensated? Also, Sue Raikes, who was a graduate student at the Lab at the same time, started looking at the structure within the upper mantle and looking at waves coming from deep earthquakes around the world. We noticed that there was a high-velocity structure that was largely beneath the San Gabriels but that extended off into the Mojave and didn't appear to be offset by the San Andreas. It raised the questions about where is the plate boundary at depth? How far does it extend to the mantle? Is the crust just sliding over the mantle, so there's a decoupling that extends across the plate boundary? That was intriguing. When I did my thesis defense, I'm told that after I left the room, we had a visiting Russian scientist who jumped to the board and said, "OK, Candidate passes. Now, we vote on who believes him." [Laugh]

ZIERLER: In looking at all of the data, what was the instrumentation that was both important both for capturing the data and determining when you would go out and do field work, and when you would be back at the lab interpreting it?

HADLEY: Most of the data I used came from the Southern California Seismic Array. It was pretty easy to get the data. Initially, when I first got to the Lab, we were recording it on film, which had to be developed and then read on special readers. Seems primitive today, but that's how we did it. We did some field work, some small seismic surveys. I used to go out and put a device on top of explosives at a quarry so I could measure the exact time of explosion. There were a few times when we'd go out and dig a hole 80 or 90 feet deep, load a ton of dynamite down into the whole, and rock Southern California so we could get velocity measurements all over. Did some work also in the geothermal fields down in Brawley and the Salton Trough area. But most of the data came from the Southern California Array. I did a study on the old Long Beach earthquake that occurred in the 30s. The old seismic records we had at the old Lab, you'd go up, it was dusty, and there were great, big boxes with paper records stacked to the ceiling. You'd find the box you wanted, pull out the records. It was a fun time.

ZIERLER: To the non-specialist audience out there, I wonder if you can give a sense of looking at the data, making interpretations. How do you make sense of what the data is telling you? What are the big questions that you're trying to answer?

HADLEY: We looked at two things, I think, pretty commonly. How long it takes waves to travel through segments of the earth, and how we could divide it down into smaller and smaller segments so we could have higher and higher resolution of how the velocity changes around the area. Then, as we studied earthquakes, trying to understand the mechanics of the earthquake, we were more interested in the wave shapes, how the wave looks, how we can mathematically model those waveforms to understand if the earthquake was a thrust fault, a dip-slip, strike slip, the nature of the earthquake, what it told us about the stress in the area, how big it was. In the past, we had all used the Richter scale to judge size, but Hiroo and Don Anderson really pioneered moment magnitude, which was a much more robust measure of energy release for the really large earthquakes. That all could come out of the modeling of the wave shapes and amplitudes.

ZIERLER: When you're looking at the data, and you have to make determinations, arguments, "This means this, and that means that," how much leeway is there in terms of you just needing to make a decision and say, "This is what it means," and be prepared for other people saying, "No, actually, this is what it means."

HADLEY: [Laugh] I think that's the nature of science. I think we all need to be clear on what the data says and doesn't say. I think if you've done your homework, you have the right to put forward some hypotheses, but they should be labeled hypotheses with disclaimers of where you're weak or need more data. But I think that's the nature of it. The Seismo Lab was, and I think probably still is, renowned as being a brutal place to do a seminar. We'd have people come in from all over to do seminars at the Lab on Friday afternoons. It was always a challenge of, "How can we tear this apart? Nobody's got it right." It was a tough audience. [Laugh] But that's how you understand the strengths and weaknesses of an argument and what alternative interpretations there are.

ZIERLER: What were some of your key conclusions in your research for your thesis?

HADLEY: I think the issue about the nature of the upper mantle in Southern California, what the implications of that are for the plate boundary was, I think, motivation for a lot of follow-up work. I just saw a really lovely paper by Humphreys that has used the seismic arrays all over the Western US and earthquakes around the world to define the mantle structure in fairly fine detail. His work really sharpens the focus on the early ghost-like figure that we had surmised from our data back in the 70s. But it was really fun to see that coming together.

ZIERLER: How did you see this research relating or not to what Hiroo was doing?

HADLEY: Hiroo's interests are broad. [Laugh] He was always a willing collaborator, always helpful. One of the very first papers we did, I think Hiroo was the first author, was on some of our early work on Southern California velocity models, and I still see references to that today. And I think Hiroo pulling me in on that paper–we went out and did some seismic surveys in the Mojave–really sharpened my focus on Southern California tectonics.

ZIERLER: There's always the question of localized study and extrapolating that for broader truths in the field. With that in mind, what did you learn about Southern California's geophysics and seismology that was regionally unique, and what could you apply elsewhere on the globe in geophysics and seismology?

HADLEY: Wow, I haven't thought about that in a long time. [Laugh] I'm not really sure how to answer that. I think just the experience of those studies equips you to jump into other areas around the globe and have an idea of how to bring data together, what to look for, what you needed to find out to solve the question. And Southern California, and particularly in the Western US, when we were there, I remember Lee Silver had a seminar class he taught, we'd all go to his house and have a beer, and Lee would give us a bunch of papers to read. We'd have a conversation about the geology and tectonics of some problems within Southern California, and those were always wonderful, spirited, insightful discussions as Lee talked about the evolution of the Western US. How the Western US overrode the spreading center, how that rippled across, leaving, as Clarence Allan used to call them, the caterpillars crawling north in the basin range - the mountains - ultimately to the Rocky Mountain front and the uplift of the Colorado Plateau. It raises the question of what / where is the plate boundary? It certainly comes up the Gulf of California through the Salton Sea, but where does it really go from there? We think of San Andreas as the boundary, but the bulk of the earthquakes come out to Southern California, then up Owens Valley. A huge earthquake occurred in the Owens Valley in the 1800s. I think all of that raises some interesting questions about the real nature of the evolution of the Western US.

ZIERLER: Who was on your thesis committee?

HADLEY: Of course, Hiroo. I think Helmberger must've been. Our Russian friend, Boris. Probably Harkrider. I did some surface wave studies to try to understand the mid-crustal shear wave structure. Arden Albee might've been, I can't remember.

ZIERLER: Do you remember the Seismo Lab as being an intellectual center? In other words, a place where senior people in the field would want to come, share research, and discuss what was happening?

HADLEY: Oh, absolutely. We'd routinely have visiting scientists who would come and spend time with us.

ZIERLER: Was it formal, like seminars? Or was it more informal, just hanging out, people chatting over coffee?

HADLEY: Both. If you were visiting the Lab, you were expected to do some seminars, share what your research is, why you were excited about what you were doing. But coffee was, and I hope still is, a central role for sharing ideas and cross-fertilization. If you had an idea or a question, it was pretty common to just wander into somebody's office, sit down, and have a conversation.

ZIERLER: What about the instrumentation? Was the Seismo Lab a place that had instruments that weren't available anywhere else?

HADLEY: I can't say they weren't available anywhere else, but there was certainly an abundance at the Lab, and it had a long history of building really unique instruments to solve certain problems. Some of the long-period seismometers, the broadband seismometers that would give us high-fidelity signals, strainmeters. The Lab always pioneered, and I think still does. I'm sure you're aware a fellow at the lab is now working using optical fibers as a seismic device, which is quite innovative. I think instrumentation is important. It's hard to do research if you don't have data. That's a critical element. [Laugh] I think that's been an important part of it.

ZIERLER: After you defended, what prospects were available? Was seismology and geophysics a good field to go into at that point?

HADLEY: Well, Bob Hart and I started our company while I was still a graduate student, so we transitioned from the Lab to an office in Arcadia. Don Helmberger was involved with the startup. We debated what we wanted to do after we graduated. The Lab, and Caltech in general, groomed you to be largely in academia. The Seismo Lab, certainly either academia or with the US Geological Survey up in Menlo Park. That was sort of your expected route. When Bob and I started the company, the Seismo Lab was very supportive, but the geologists thought that we had committed a terrible sin, that going into a commercial enterprise was not right. We had quite a discussion on that topic for a while. [Laugh]

ZIERLER: What was the game plan at that point? Had the Seismo Lab produced graduate students who went into private ventures like this before? Or were you really among the first?

HADLEY: I'm not sure how far back it goes. I know that Stewart Smith was certainly engaged in private consulting work. In fact, most of the faculty were involved in consulting in one form or another with oil companies or whatever. But it wasn't a common thread. But we felt everything associated with academia, writing proposals, looking for funding to take care of ourselves and our students, maybe doing some consulting on the side, was stuff we could do ourselves. We didn't necessarily need to be part of an institution to continue doing the research we wanted. Bob and I started a company. I had been doing consulting as a graduate student for Southern California Edison on the licensing of San Onofre nuclear units two and three, working on trying to model strong ground motion to try to estimate what the likely shaking would be in a realistic-sized earthquake offshore. I continued on that as a consultant. And we did quite a bit of work for the Department of Defense, trying to understand the Russian explosions, how big they were, if they were above or below the test ban treaty. And we'd been working on a lot of contracts as a graduate student that were USGS contracts. Bob and I thought, "Well, we can write proposals just like in academia, we can get them funded, we can hire people and have a research company." It sounded challenging and fun, so we did.

ZIERLER: What exactly was the niche that this company fulfilled? Who were the customers?

HADLEY: Department of Defense provided a lot of funding. We developed some complex codes for modeling wave propagation in complex 3D geologies. The Russians were setting off some explosions in the Kamchatka area, or it was a concern that they would, and in very complicated geology. They were also setting off explosions in salt domes, basins, and so forth, which really distort the waves as they leave the basin. We developed a lot of software for modeling wave propagation in complex geologies. In 1981, we attended an exploration geophysics conference. The oil companies were just starting to do 3D seismic surveys back then. Amoco had done the first large-scale 3D survey and had completely missed the target because the geology was quite strongly dipping, and it bent the seismic waves in ways that they had not anticipated. And we had the tools to model that. Instead of looking at how the seismic energy leaves the bottom of the basin, we turned the software around and looked at how it manifests as it hits the surface of the earth, where they record the energy, and provided tools to design better seismic surveys, and helped model those surveys. We transitioned from being a consulting services company into a software company.

ZIERLER: What were some of the advances in computation, both on the hardware and software sides, that made that transition possible at the time?

HADLEY: I think just increasing CPU power. I'm still programming. Even today, I'm sure I'll write a few lines of code. But when I write stuff today, I think, "Gosh, in my younger days, I would've needed a Cray computer to execute it." Today, in a flash, it's done. I think the increasing power from those old paper tapes to that 64k machine we had–when we had a machine that could process a million instructions a second, we thought, "Man, we've arrived." That just seems primitive today. I think increasing CPU and memory power allowed us to go to bigger, more complex problems.

ZIERLER: Did that give you deeper insights into seismology as a result of having that better computational power?

HADLEY: Yeah, I think so. By that point, we were more involved with trying to improve our ability to help the oil and gas industry be more efficient at finding resources. Bigger power meant we could do bigger problems and be more useful.

ZIERLER: Is this where Halliburton enters the picture?

HADLEY: Later on. We grew the company up, were well over 100 people, things were going great. Then, overnight, I think it was July of '88, the price of oil went to $12 a barrel. Hard to believe. And the oil business is an international business, so capital budgets were frozen around the world. Most software was bought in the fourth quarter with people's disposable capital. There was no fourth quarter for us. There were just no sales to be had. We were in trouble, and ultimately, we were acquired by Halliburton. We stayed on there for almost four years.

ZIERLER: I wonder if you can explain what your area of expertise does for a company like Halliburton.

HADLEY: I was asked to pull together a team of about 300 people, and we were interested in combining the data from the different operating units of Halliburton in order to build a data volume that brought everything together about what we knew about an oil field, the seismic data, the well log data, how the wells were completed, any information about permeability and flow in the reservoirs. The goal was to bring all this together. Our vision was that with the growth in the computer business, the companies that could integrate broadly across all of the disciplines and bring that to bear on where to drill the next hole, how to flood the reservoir, how to move fluids through it, would bring competitive and economic value to society. That was our goal.

ZIERLER: How long did you stay with Halliburton?

HADLEY: Four years. We had a four-year earn-out, and we stayed for four years. At the end, unfortunately, Halliburton decided they wanted to go back to just pressure pumping cement, and they divested all of the digital groups, probably a billion dollars or more of company assets. Then, a few years later, they bought them all back again. It's a sad story, but that's what it was.

ZIERLER: What happened to you as a result?

HADLEY: At that point, we really liked living here the Northwest. Been here since '81. We had been working successfully in the oil patch out in Seattle, and that was a bit of a strain. It appeared that if we wanted to stay in the oil patch, we'd have to move to Texas. For personal reasons, we wanted to stay here. I found a young company, young entrepreneur and four or five engineers trying to build a knowledge system, and I thought that was interesting. I came onboard to organize the work and build the products. That was fun, we got that company public just as part of the dot-com boom, which was financially quite fun. But then, I was recruited into diagnostic cardiology, and I've been doing that ever since.

ZIERLER: That initial company, were they doing cardiology, or that was a separate connection?

HADLEY: They were a grand old cardiology company. They'd been formed by a guy, Wayne Quinton, who was a bioengineer at University of Washington here in Seattle. He worked with Dr. Bruce to develop the Bruce protocol for treadmill stress tests. He formed this company, developed numerous life-saving products, and it went through several lifecycles. That's when I came in, in '98, to rebuild the team and the products.

ZIERLER: What was the intellectual process like realizing that your expertise in waves as they related to seismology would be relevant here? Was there a game plan? Had anybody made that leap before? How did that come together?

HADLEY: I came in with the goal of getting bright engineers–it was largely a software endeavor. Some hardware, but mostly software. My first need was to build a team, get some strong people in. Parallel with that, I started reading everything I could in cardiology and became really fascinated with the electrical structure of the heart. Amazingly complicated organ. I very quickly realized that waves are waves, "This all looks very familiar." I stayed there until 2007. We got that company cleaned up, got it back in the public markets. We acquired another grand old ECG company called Burdick, folded that in. Then, we also acquired an AED company that makes automatic defibrillators. We got that going, and at that point, I was tired, so I nominally retired in 2007, but I built a strong relationship with a grand old guy in cardiology, Dr. Vic Froelicher down at Stanford. I retired, but Vic and I continued to work together. Vic has a huge digital dataset. Here we go again, data's important.

I knew how to write the codes, do the analytical part, and Vic knew all the clinical, so together, we started publishing papers and just having fun. Then, about 2010, one afternoon, Vic and I were talking - Vic does the cardiovascular screening for the incoming Stanford athletes as well as the 49ers. He said, "The ECG devices we use for screening young people for risk of sudden death are not very effective. They have a false positive rate of 15 to 25%. You can't test people where every fourth one is a false positive." Vic thought that we should focus some energy on sudden death in young people. I wasn't sure the world needed another cardiograph, but the research seemed like fun. Vic pulled together a group, I participated in that, and we did a paper in a journal called Circulation, one of the leading journals for the American Heart Association, on the criteria to look for in young people–I next attend a conference at Stanford on sudden death, and at the end of the conference, I went up to Vic and said, "OK, I get it. Let's see if we can do something."

Vic and I pooled our dollars together, and I hired some guys I'd been using for electrical mechanical engineering, and we built a high-resolution, low-cost cardiograph. Usually, the cardiographs are these great, big boxy things. We built a device that was Bluetooth-connected, about this big, ran with a PC. Got it through the FDA. That's become kind of the de facto standard. We've gotten the false positive rate down to about 2%. I almost hesitate to call them false positives because I think we're finding kids that have things that really need to be looked at. When we were building the tool, I would take an ECG on anybody who would sit still, and I found my son had a defect in his heart that was undiagnosed. He had a 15-millimeter hole between the left and right upper chambers of his heart. Without closure, he probably would've had atrial fibrillation in his 40s and heart failure in his 50s. I know we've saved a lot of lives with that device, and we'll continue, and I take a lot of pride in knowing that we've done something that can perhaps save people's lives.

ZIERLER: What exactly was the innovation that got that false positive rate down so significantly?

HADLEY: I think that goes back to my seismic days. You can't do any better than the quality of the data you have. Most ECG devices capture data at a rate of about 500 samples per second. I boosted it up to 1,000. I wanted really high-resolution data. Young people have higher-frequency signals, and I wanted to capture that with high fidelity. Generally, the signal is captured at a resolution of about five microvolts. I wanted better, so we were down at 0.7 microvolts, big improvement there. The standard test is a ten-second recording of a heart, but young athletes have slow heart rates, so in ten seconds, you might only capture four or five beats. We extended the recording time out to 16 seconds so that we get more beats, and when we averaged those beats together, we'd get the best estimate of the waveforms. We had more beats to work with, and we'd have higher reliability.

Then, I was super careful in signal processing and the analysis. And we worked with a lot of doctors on the right criteria. That's been critical. I think a combination of careful data-collection and improvements in the criteria. One of the co-authors of the paper we published in Circulatio is a doctor here at UW. Dr. John Drezner is head of the sports group at UW and team doctor for the Seahawks. John continued the work on criteria. John hosted two large conferences here in Seattle with international cardiologists on criteria. We've had, for a while, what we call the Seattle criteria, which further lowered the false-positive rates, and then recently, that's been adopted internationally. Now, it's called the International Consensus Criteria. That criteria has lowered false positives down now where an ECG is a very practical, low-cost way of identifying kids at risk.

ZIERLER: It really begs the question, what is the blind spot in medical or even cardiac education where you coming in with your sensibilities or your research areas identified these problems with people that do heart health for a living were not able to themselves?

HADLEY: I think it depends on the discipline. Most doctors are focused on following established standards, established criterion methods, and applying them. Then, there's a small group interested in the actual research of what could be done better. I think that most doctors don't come at this with that focus. The doctors and researchers who collaborated on this International Consensus Criteria was probably 40 people worldwide. It's a pretty small cohort of people interested in this area.

ZIERLER: How widely have these technologies and innovations been adopted?

HADLEY: Medicine is slow to change. We have been slowly making in-roads on adoption of screening for the kids. There's an old guard in medicine that worries that if you screen a child, and you have a false positive, and you do additional tests, and all those tests have false positives, that you might end up doing some kind of a procedure on a kid that shouldn't have been done. And I think that was a legitimate concern when the false positive rates were 15 to 25%. I don't think that's true anymore. The kids we see have real problems. We do mass screenings, we'll go into a high school and screen 300 to 500 kids over the course of a day, and we almost always find one to two kids who may not die but certainly have issues that predispose them toward sudden death and will likely have impacts on their health over the course of their lifetime.

ZIERLER: From a public health perspective, what are some policies that should be adopted or more strongly endorsed as a result of what you've been finding?

HADLEY: I think there's a slow evolution in that direction. I think it's starting to gain momentum. We're working with the military, and we'd love to see all young recruits screened before they come into the military. There seems to be a growing consensus that that would be a good thing to do. There are tests ongoing right now. I think at West Point, we have a clinical study going right now on the efficacy of the device. But there's growing interest in screening people. The Society of Pediatricians is coming around to the idea that maybe screening and getting a baseline ECG on a kid isn't such a bad idea after all. It's been slow, but I see it happening.

ZIERLER: Are there other countries adopting this model that are sort of quicker to the draw than the United States?

HADLEY: Yes. Italy was a forerunner in this, and the Italian colleagues have been very helpful. There's a genotype in Italy that predisposes people to a form of cardiomyopathy called Brugada, and they were quite interested in how they could identify Brugada and help kids. The UK has been a big supporter. They have a leading doctor over there who does all the screening for the high-end soccer teams and sports, very bright, insightful guy. He's been super helpful in developing the criteria in collaboration with Drezner up here.

ZIERLER: Just to bring the conversation right up to the present, what are you working on currently?

HADLEY: We have a device that's in the market today. It's a patch, single-lead. It can be worn for seven days. This little puck samples the heart 250 times per second at a sub-microvolt level. It can be downloaded in the clinic, and the computer will automatically process the data and give the doctor a report in about five minutes. The normal standard of care for the market leaders today, you wear the puck, they send it to a service center, and four to six weeks later, the doctor gets the report. Meanwhile, you're walking around potentially with cardiac issue that caused the doctor to want to put a monitor on you. We think the timeliness and the doctor owning the data is a big benefit. We're working now on the next generation of this. Much like in seismology, if you look at things from different angles, you see different things. We're doing a two-lead version of this, so we'll look at the heart from different directions, and that gives us a good view of what we call the frontal plane of the body, the whole front. There's no angle that can escape our detection in how the beat is oriented.

I think that will extend the value of this. It'll be a ten-day recorder. And we're also putting a three-axis accelerometer in it so that we can correlate activities of the heart with the physical activities of the patient. We can also tell when they're supine, standing, jogging. We think that will add a lot more insight into the heart's behavior. If you're exercising and your heart's not racing up, you've got a problem. If you lie down, and your heart does weird things, that's another kind of problem. I think it's going to be very helpful. I'm excited. We'd like to get this product in to the FDA by the end of this year, before Thanksgiving if we can. But I think it sets the stage for the next generation of products, and it'll open up more things we can do. I think with that information, I can probably do a good job of detecting sleep apnea and characterizing it. Certainly, sleep apnea is a major issue that causes collateral issues and cardiomyopathy, so I'm excited about that.

ZIERLER: The question everybody is always curious about, for this research, what are some of the big takeaways you've learned about heart problems as they relate to genetics and congenital defects versus lifestyle choices?

HADLEY: Wow. [Laugh] That's not an easy question. Maybe a way to answer that is to look at the work we've done with young people in characterizing risk. This work was done here at UW by Dr. Drezner's team and Dr. Kim Harmon. They've worked closely with the NCAA on stratifying risk. Death rates in youth had previously been done by going into a community and saying, "In Pasadena, we think we have 75,000 kids under the age of 18. We scanned the newspapers, and we've seen five kids who have died over the last three years." We come up with an estimate of how many kids per 1,000 or 100,000 die per year. Those estimates have always been pretty suspect. If you had a star player who sinks the ball and dies, that probably makes the paper. If you're a football player, and you die in your sleep, that might not make the paper. There have always been a lot of questions about the numerator and denominator in that ratio.

The NCAA is a perfect experiment. We know exactly how many kids are in the NCAA, we know their ages, nobody dies without being recorded by the NCAA, and there's generally autopsy work available. Dr. Harmon went through that, and for the first time, I think, was able to characterize death rates. And they're stratified. Men are about twice as likely to die as women. African Americans are about twice as likely to die suddenly as Caucasians. And they're stratified by sport. Sports that causes large surges of adrenaline, like basketball and football, where you start and stop, have about twice the death rate of golf. To answer your question, there's a lot of stratification of risk whether it's genetic, male, female, Caucasian, African American, and the lifestyle aspect of how one's heart gets exercised.

ZIERLER: For the last part of our talk, I'd like to ask a few broadly retrospective questions, then we'll end looking to the future. To go back to something very interesting you said earlier, how might you reflect on the way that the Seismo Lab and Caltech taught you how to think that provides guidance for the very interesting career path that you ended up on?

HADLEY: I think the Lab, and Caltech in general, teaches people to not be afraid to just jump in, to enjoy the experience. I think it also teaches you, and I don't know how to describe this, to quickly understand what's noise and what's likely to be pertinent to the problem you're trying to solve. I'm sometimes amazed, in talking to other people, that things to me that seem obvious, I think because of my background, what's important about the issue and what's less important, come from experience and doing it a lot, and I think Caltech deserves a lot of credit for that.

ZIERLER: Do you have a sense, given that you were, in many ways, a pathbreaker, going into private industry, that Seismo Lab graduates in subsequent years have taken a page out of this playbook and gone on to non-traditional fields in the way that you have? Has that become more common over the years?

HADLEY: I actually don't know. That's a good question. At our first company, Bob and I hired several graduates out of the Seismo Lab, so I know we probably confused and diverted some. [Laugh] But most of the people I know are still in academia in various, great, successful roles.

ZIERLER: Last question. Going back to your initial interest in understanding earthquakes in Southern California, obviously, the interest there comes from a social impact perspective. You want to understand these things because they influence lives. Obviously, as well, your work in cardiac science has a social impact as well. How do you compare the two in terms of deriving satisfaction in pursuing science that ultimately is helpful for people?

HADLEY: I take a lot of pleasure in that, candidly. When I came to the conclusion, perhaps prematurely, that we weren't going to predict earthquakes, I became more interested in if we could predict ground motion and how it might be leveraged to improve safety and health. That's kind of what led me to the San Onofre projects. Certainly, in cardiology, I get a lot of pleasure. I can tell you dozens of stories of kids we've found. I'll tell you one. We were doing a screening here in Seattle, down in the South Seattle area, and we found a young Black kid who had two major defects. He had something called Wolff-Parkinson-White, which is an abnormal circuitry in the heart, and he also had hypertrophic cardiomyopathy, which is an over-thickening of the heart muscles. Sometimes those two come together, but they can be quite lethal. He had two siblings that had died suddenly and, given the neighborhood and the area he was in, they had been written off as overdoses, which certainly had clouded his life and his family. And in fact, he was suffering from a genetic cardiac condition which almost certainly killed his family members. To be able to help him probably live, and bring some clarity to his parents, that's pretty rewarding.

ZIERLER: Well, Dave, on that note, it's been a great pleasure spending this time with you. I'm so glad we were able to do this. I'd like to thank you so much.

HADLEY: It's been fun, David, thanks a lot.