Dr. Daniel Burkhoff on Patient Care Through Pressure-Volume Loops
The Protected PCI blogging team recorded our latest podcast at the Advanced Hemodynamics workshop in Frankfurt, Germany where Dr. Daniel Burkhoff from Columbia University lectured on hemodynamics. Dr. Burkhoff has reintroduced the topic through his work as a lecturer, a researcher, and developer of the Harvi app on hemodynamics. In this podcast, he'll discuss how cardiologists and interventional cardiologists know about pressure-volume loops and their significance in patient care.
Interviewer: So we're here at the Advanced Hemodynamics workshop sponsored by Abiomed in Europe in Frankfurt, Germany, and we've just come from a lecture by Dr. Daniel Burkhoff from Columbia University on hemodynamics. Dr. Burkhoff has reintroduced the topic for many cardiologists and interventional cardiologists through his work as a lecturer, a researcher, and developer of the Harvi app on hemodynamics. And what I was struck by in the lecture today was Dr. Burkhoff's helping us understand patient care through pressure-volume loops. So, Dr. Burkhoff, what would you think that we should promote as important educational things for cardiologists and interventional cardiologists to know about pressure-volume loops and their importance of patient care?
Dr. Burkhoff: Thanks for the question. I think that what we've learned is that through a better understanding of the hemodynamics of circulatory support, we're gaining the appreciation that not all devices really work the same way. And it's really through our work with the fundamentals of pressure-volume analysis that we've been able to come to this conclusion. In particular for high-risk PCI, if we look at the differences between how the balloon pumps work and how an Impella transvalvular ventricular to aortic pump work, we see that there are significant differences. And specifically what we've learned on the theoretical side, is that a balloon pump is able to supplement what the heart is able to do, and as ventricular function deteriorates during a balloon inflation of a left main or a last remaining vessel, for example, the level of support that's provided by the balloon pump decreases.
And this is really the fundamental difference between a balloon pump and a ventricular assist device, like Impella, where the degree of support is independent of the level of contractility of the ventricle. So with an Impella, in contrast to a balloon, as ventricular function decreases during the balloon inflation, we're able to maintain perfusion to the body, maintain blood pressure, maintain perfusion of the kidneys, the brain, you have an awake patient, and the heart, also, does not deteriorate as much because you're able to maintain some coronary perfusion via collaterals. So it's this comprehensive circulatory physiology understanding, which is revealed through pressure-volume analysis, that we're able to understand the differences between these different devices.
Interviewer: In your lecture you said an intra-aortic pump is not really a circulatory device. Can you elaborate?
Dr. Burkhoff: Well balloon pumps are a form of circulatory support, they're just not particularly effective because all they do is to provide a little bit of after load reduction to the ventricle, and this boost in pressure during diastole, which has the potential beneficial impact on coronary blood flow. So that is really the thrust of what a balloon pump can do, but we really need to contrast that to a real ventricular assist device, a real pump, which is actively putting energy into the system to take blood from the ventricle, dump it into the aorta, take over for the work of the heart, not supplement what the heart is doing.
The other important part of this pumping blood out of the ventricle is the impact on unloading the ventricle. So really, by the act of removing blood actively from the ventricle throughout the cardiac cycle, we're getting much more effective unloading, and that unloading has a potential impact on the oxygen demands of the ventricle, which, and especially in the setting of an MI or in a high risk PCI, can have potential effects to preserve myocardium.
Interviewer: And finally, what should physicians be considering when they think about Protected PCI and mechanical circulatory support?
Dr. Burkhoff: In summary, if you have a patient that falls into the category of high-risk PCI, for example, mainly, in particular, a low ejection fraction and a last remaining vessel, where you know when you inflate that balloon you're going to have a significant decrease in contractility, and you want to maintain perfusion to the body, to the kidneys, to the brain, and, also, residual coronary blood flow, you need to use a pump, an active pump. And a balloon pump really does not fit that bill, whereas a trans-valvular ventricular to aortic pump, like the Impella, is really what's needed.
Interviewer: To hear more interviews or learn more about Protected PCI visit ProtectedPCI.com
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