Willard Applefeld MD
@WApplefeld
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Critical Care Cardiologist @DukeHeartCenter by way of @DukeCardFellows, @NIHCritCare, & @OslerResidency | Views are my own
Durham, NC
Joined April 2013
He was also an exceptional clinical trialist who advanced the field of critical care with his rigorous devotion to science and ethical approach to clinical trials. I shall miss his expertise .
Sad news:. Another giant in Critical Care, Professor Rinaldo Bellomo, passed away this morning. He was born in Reggio Emilia, Italy & emigrated to Australia in the 1980s receiving his medical degree from Monash Medical School in Melbourne. He completed fellowships in nephrology,.
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RT @DanMarkMD: “Solely applying a P value threshold or 95% CI to determine if a treatment works or not is an [often misleading] oversimplif….
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RT @SarasVallabhMD: As we start formalizing training milestones in #CriticalCareCardiology, @WApplefeld, #JakeJentzer, and I discuss proced….
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The history of echo is fascinating and I could go on for hours but that will just devolve into a discussion of echo physics. I would highly recommend BME 543 at Duke which is still taught by Kisslo and von Ramm and is available to undergrads, cards fellows, & sonographers.
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Phased array scanning not just in one plane but in multiple allows for 3D imaging (also invented by Kisslo and von Ramm at Duke) and makes much of structural echo possible today.
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Applying the Doppler principle and looking for phase shifts in the frequency of transmitted vs returning sound allowed for Doppler imaging and the assessments of velocity changes which allowed for pressure calculations using the modified Bernoulli equation.
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Sweeping across your FOV takes time as you have to send-receive along each scan line so phased array echo imaging doesn’t have the temporal resolution that M mode does.
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This meant you could rapidly sweep across a field of view and create a 2D picture of a structure. If you swept enough times, you could see structures as they moved dynamically. The phased array echo was born.
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By aligning a series of PZT crystals next to each other and slightly offsetting the timing of their discharge, you could “steer” the US wavefront
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The concept of a phased array goes back to the 1600s & Dutch Physicist Huygens & applies to optics (von Ramm started in optics). Essentially at each point on a wavefront itself serves as source of spherical wavelets, the interference pattern of which creates new wavefronts
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The echos we are so accustomed to seeing which allow us to create a representation of the moving heart (and other organs) with high fidelity are largely thanks to two really extraordinary men- cardiologist Joe Kisslo and Biomedical Engineer Olaf Von Ramm, both (still) at Duke
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b mode points displayed over time allowed for the display of the motion of structures over time with high temporal resolution - “M-mode” imaging.
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The next generation was “brightness mode” or “b-mode” which rather than displaying the amplitude, displayed a series of dots which corresponded to depth with the size and brightness correlating with the intensity of the return echo.
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Initial ultrasounds (like in the video above) used piezoelectric crystals to send an ultrasound pulse into tissues, wait for echo of sound reflects off of changing tissue densities to return back, and use an oscilloscope to display amplitude of those reflected pulsations (A-mode)
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Instead of applying radar, Hertz suggested they use Ultrasound & utilized his father’s connections as Siemens to obtain a machine which was being used in the nearby shipyards at Malmo which used ultrasound to test steel for impurities. They put it on at pt’s chest & echo was born.
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The story really begins in Lund Sweden in the 50s. A cardiologist named Inge Edler wanted to apply radar to get a noninvasive view of cardiac structures. His collaborator was a physicist named Carl Hertz (who was the son of Gustav Hertz of Nobel fame).
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Great example of what echo looked like in the early days- “Amplitude mode” aka A-mode Imaging. Echo has transformed medicine and indeed practice as we know today would be impossible without it. How did we get here? A 🧵.
On today’s Emergency! - someone with a diastolic murmur gets an emergency echo. The process…. Always start by dramatically plugging in the machine!. 1/4
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Grateful for @CosetteChampion for presenting this, @EBohula, @jameshorowitzmd, @AnnGageMD, & Mike Solomon MD MBA for moderating. Also grateful for insights from @CameronDez38454 & @PennyRampersad! Lastly, thanks to @AHAScience for allowing us to speak! Thanks for reading!!.
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I think this is a good case of heart/lung interactions. Here is a cheat sheet on heart/lung interactions
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Ultimately, we liberated vent settings, made her more comfortable, and extubated her. We then treated her UTI with complete resolution of her symptoms.
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