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Discussion on percutaneous left ventricular assist devices based on clinical trial data.
Two well-known percutaneous left ventricular assist devices are Impella devices and the TandemHeart. Other mechanical circulatory support devices which can be deployed percutaneously are the most familiar intra-aortic balloon pump and extracorporeal membrane oxygenation. You may view two other videos on these two devices on this channel.
Impella is a catheter based microaxial flow pump. It is placed across the aortic valve into the left ventricle and actively pumps blood from the left ventricle into the aorta. This is how Impella unloads the left ventricle in cardiogenic shock.
Impella 2.5 delivers an output of 2.5 l/min while Impella CP delivers 3.5 l/min which is approximately three fourth of normal cardiac output.
These devices are being used in the treatment of cardiogenic shock in acute myocardial infarction, especially to support a high risk primary angioplasty. The device is inserted prior to primary angioplasty in the cathlab.
After a negative result of the IABP-SHOCK II trial, a relook into other mechanical circulatory support devices was prompted. Schrage B et al checked the data of acute myocardial infarction with cardiogenic shock patients treated with Impella device at European tertiary care hospitals retrospectively.
All the patients had undergone early revascularization. They used IABP-SHOCK II trial inclusion and exclusion criteria and identified 372 patients for this analysis. They matched these patients with 600 patients in the IABP-SHOCK II trial.
Matching was based on baseline criteria of age, sex, mechanical ventilation, ejection fraction, prior cardiopulmonary resuscitation and lactate levels. By this process, 237 patients treated with Impella were matched with 237 patients from the IABP-SHOCK II trial.
No significant difference in 30 day all-cause mortality was identified in this retrospective analysis. Severe or life threatening bleeding complications and peripheral vascular complications occurred more often in the Impella group.
ISAR-SHOCK was a previous, prospective randomized study in which 13 patients with myocardial infarction cardiogenic shock were allocated to IABP and 12 patients to Impella LP2.5. Cardiac index after 30 min of support was significantly increased in patients with Impella LP2.5 compared with IABP. Overall, 30 mortality was 46% in both groups.
IMPRESS in Severe Shock trial compared Impella CP with IABP in acute myocardial infarction with cardiogenic shock. It was a randomized prospective, open label, multicenter trial which enrolled 48 patients.
Severe cardiogenic shock was defined as systolic blood pressure less than 90 mm Hg or the need for inotropic or vasoactive medication and the need for mechanical ventilation. In this study on mechanically ventilated patients with myocardial infarction and cardiogenic shock, there was no difference in 30 day mortality compared to IABP. 6 month mortality was also similar.
Danish Cardiogenic Shock Trial is a 10 year trial on Impella CP which was initiated in December 2012. The study is expected to be completed in January 2023.
TandemHeart is percutaneous left atrial to femoral arterial bypass system. Venous inflow cannula is inserted into the left atrium by a trans septal puncture. Oxygenated blood drawn from the left atrium is returned by a centrifugal pump into the lower abdominal aorta through a femoral arterial catheter.
TandemHeart can also be used in those with left ventricular thrombus as the cannula is not introduced into the left ventricle, unlike in Impella device. Aortic stenosis is also not a contraindication as the catheter does not cross the aortic valve. But aortic regurgitation and aortic dissection are contraindications.
Thiele H et al randomized patients with cardiogenic shock and acute myocardial infarction planned for percutaneous coronary intervention to the infarct related artery to either IABP or percutaneous ventricular assist device.
They concluded that hemodynamic and metabolic parameters can be reversed more effectively with ventricular assist device than IABP. But more complications like severe bleeding and limb ischemia, occurred with the highly invasive extracorporeal support. Thirty day mortality was similar in both groups.
Another study of TandemHeart vs IABP had 42 patients with cardiogenic shock from 12 centres. This study also documented significantly greater increases in cardiac index and mean arterial blood pressure as well as significantly greater decreases in pulmonary capillary wedge pressure with TandemHeart. Severe adverse events and overall mortality were not significantly different between the two groups.

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