Harvi Hemodynamic Simulator App Showcased at Advanced Hemodynamic Course in Frankfurt
Dan Burkhoff, M.D., Ph.D. of Columbia University Medical Center, was the first presenter at the EU Hemodynamic Support Course- Expanding Clinical Applications for Your Patients, taking place in Frankfurt. His presentation, “Mechanisms of Hemodynamic Support,” discussed the science behind hemodynamic support and pressure volume implications in high-risk PCI patients.
At the start of his talk, Dr. Burkhoff noted that it is gratifying to see that many of the hemodynamic parameters predicted in cardiac performance models many years ago, are now becoming a reality in the current era of mechanical circulatory support (MCS). Dr. Burkhoff has become the clinical expert on the science of hemodynamics and discussed the different effects that different MCS devices have on left ventricular mechanics. “We understand a lot about the left ventricle by understanding the pressure,” which includes volume loops, vascular impedance, coronary blood flow, myocardial energy, autonomic reflexes and pressure flow.
Dr. Burkhoff is the author and creator of Harvi, a cardiovascular simulator for hemodynamics, which is available as an iPad app. Harvi permits the simulation of different clinical scenarios, including high risk PCI, allowing users to compare support devices, such as the IABP, the Impella® line of heart pumps and ECMO.
During the presentation, Dr. Burkhoff used the Harvi simulator to illustrate the pressure volume (PV) loop in a patient with a left main stenosis, demonstrating a reduction in coronary flow and cardiac performance, which is shown by the increasingly smaller PV loop. He then uses this patient simulation to demonstrate the effects of different devices, taking us first to the IABP and then the Impella device.
With the IABP in place during the PCI, there is increased pressure in diastole with increased coronary flow. The PV loop then shifts to the left. There is also an increase in cardiac output by 0.5 l/min and no change in the diastolic pressure, since the IABP provides minimal volume but not pressure unloading.
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Additionally, he notes that there is a loss of contractility and circulatory perfusion to the rest of the body. “The IABP can only supplement, it is not a real circulatory device.”
Then, Dr. Burkhoff chose a transvalvular, axial flow pump, like the Impella device, in the simulator. There is minimal change to the systolic pressure and a rise in diastolic pressure, indicating lower pulse pressure. The continuous flow from the Impella maintains the diastolic pressure. With this, there is a continued increase in coronary perfusion and a change in the PV loop, which becomes more triangular (less rectangular) due to the volume unloading and lowering of the myocardial energy requirements by the heart.
Dr. Burkhoff explained that during a Protected PCI with the Impella heart pump, when the left main coronary artery is occluded by the balloon, there is maintained organ perfusion despite loss of heart contractility and waveform pulsatility. However, there is reduced myocardial energy consumption and the ventricle is in a state of hibernation. This also results in electrical stability for the heart during the PCI – the amount of support is independent of what the heart is doing unlikethe IABP, which is dependent on heart contractility and heart rhythm.
He then showed a case from Dr. William O’Neill of Henry Ford Hospital in Detroit, to demonstrate the consistency of the simulator’s prediction with an actual case of Protected PCI. The patient’s left main was treated, showing a loss of pulsatility and contractility, but despite this, the patient had continued organ perfusion (brain, kidney, liver) due to Impella device support.
“This is looking behind the curtain of what is happening in the cath lab,” explains Dr. Burkhoff in reference to the simulator’s benefits. “The Impella gives the operator time to perform his operation and do more work to get a better result with PCI. You see restoration of flow, return of pulsatility, and contractility.”
Dr. Burkhoff noted that a paper focusing on the subject of hemodynamic support is expected to be published next month in the Journal of American College of Cardiology.
The Impella 2.5 system is a temporary (<6 hours) ventricular support device indicated for use during high risk percutaneous coronary interventions (PCI) performed in elective or urgent, hemodynamically stable patients with severe coronary artery disease and depressed left ventricular ejection fraction, when a heart team, including a cardiac surgeon, has determined high risk PCI is the appropriate therapeutic option. Use of the Impella 2.5 in these patients may prevent hemodynamic instability which can result from repeat episodes of reversible myocardial ischemia that occur during planned temporary coronary occlusions and may reduce peri- and post-procedural adverse events.
Protected PCI and use of the Impella 2.5 is not right for every patient. Patients may not be able to be treated with Impella if they have certain pre-existing conditions, which a cardiologist can determine, such as: severe narrowing of the heart valve, severe peripheral artery disease, clots in blood vessels, or a replacement heart valve or certain heart valve deficiencies. Additionally, use of Impella has been associated with risks, including, but not limited to valvular and vascular injury, bleeding, and limb ischemia in certain patients. Learn more about the Impella devices’ approved indications for use, as well as important safety and risk information at www.protectedpci.com/hcp/information/isi.