Dr. Navin Kapur Explains Active Unloading with Impella^™

Navin Kapur, M.D., FAHA, FACC, FSCAI, FHFSA, provides an in-depth explanation of the unique physiology of Impella support, highlighting active unloading. Impella, a transvalular pump, sits in the left ventricle (LV) and ejects blood from the LV into the aorta and systemic circulation. “So unlike an intra-aortic balloon pump or VA ECMO,” Dr. Kapur states, “this is positioned in the LV and it directly reduces both pressure and volume inside the ventricle.”

Dr. Kapur describes what pressure-volume (PV) loops look like in patients with heart failure or acute myocardial infarction (AMI), as well as what PV loops look like in patients on Impella support. He states that pressure times volume equals myocardial oxygen consumption, also known as the heart’s workload, and discusses how Impella significantly reduces the workload of the native heart while increasing mean arterial pressure (MAP) for the rest of the body. “On the Impella console,” Kapur explains, “you may see an arterial waveform and then you’ll see a ventricular waveform, and you’ll see separation between the two. And that’s something called ‘VA uncoupling.’” He emphasizes that this VA uncoupling means that the pump is maintaining the arterial pressure and the ventricle can rest.

In an AMI patient or a patient with AMI cardiogenic shock (AMICS), there is a mismatch between oxygen supply and demand in the heart. “So the idea of putting a patient with AMI shock on a transvalvular pump is that now you can normalize the demand even in the setting where you have impaired or normal oxygen supply,” Kapur explains. “So you get that uncoupling of the venticle from the arterial system, the heart is resting, while the systemic blood pressure is improved.”

Dr. Kapur points to results from the DanGer Shock randomized controlled trial (RCT) to highlight the functional efficiency of Impella. “In the DanGer trial, when you look at the overall cohort of patients, there was a reduction in overall mortality. But when you got to patients who had a systolic blood pressure less than 82, all of the sudden now your odds ratio was 0.34, which means the number needed to treat was around 3. So that’s a really powerful observation in the DanGer trial.” Dr. Kapur highlights that Impella functions most efficiently in patients with impaired cardiac function undergoing high-risk PCI, in patients with AMICS, and in patients with heart failure cardiogenic shock with impaired contractility and dilated hearts.

Dr. Kapur concludes by emphasizing the importance of understanding how Impella works and why the physiology of the pump and the patient have to match up. “And that’s why you’re starting to see more use of Impella,” he states, “for the sickest patients in the hospital undergoing intervention or who are coming in in cardiogenic shock.”