Temporary Right Ventricular Support with Impella Recover RD Axial Flow Pump

Post-cardiotomyright ventricular failure is a serious complication that frequently results in adverse outcomes. We reviewed our experience with the Impella Recover RD (Impella Cardiosystems GMbH, Aachen, Germany). From January 2007 to December 2007, 7 patients (5 males, 54 + 7 years old) had this device implanted for temporary support after heart transplantation in 4, after repeat mitral valve replacement in 2, and with a left ventricular assist device in 1. Devices were implanted during initial operation ( n = 5) or shortly thereafter ( n = 2). Six patients underwent implantation without cardiopulmonary bypass. Effective support with pump flows of 4.0-4.5 L · min−1 and adequate unloading (central venous pressure decreased from 15.3 ± 1.4 to 9.4 ± 1.2 mm Hg) was achieved in all patients. Patients were assisted for a mean duration of 4.9 ± 4.5 days. Three patients could be weaned after 7.0 ± 5.6 days of support and underwent device explantation without cardiopulmonary bypass. One of these patients died of recurrent right ventricular failure, 2 remained stable but died later of sepsis. The patient with a left ventricular assist device was switched to an alternative device for prolonged support. Two patients experienced pump dysfunction. Our preliminary experience shows that the Impella Recover RD is an effective device that can be easily implanted and explanted. However, its mechanical reliability needs to be improved.

Comparison of Dog and Pig Models for Testing Substernal Cardiac Compression Devices

Subtle anatomic differences between species can be a critical consideration when determining whether a given animal model is appropriate for surgical research purposes, especially when testing biomechanical implants. This study compares the effectiveness of two common animal models (dogs and pigs) in testing a balloon based cardiac compression device designed for substernal placement. Pigs were used in acute studies using an infarction model of heart failure, whereas dogs were used in chronic experiments in which heart failure was induced via rapid pacing. Systolic cardiac compression was accomplished in both species using identical balloons inflated between the sternum and right ventricle with every heartbeat. Results showed the device to be much more effective in pigs, where cardiac stroke volumes returned to normal with balloon assistance (14.7 +/- 1.9 to 37.8 +/- 9.2 mL, p < 0.005). Stroke volumes in dogs, however, remained essentially unaltered by balloon activation (28.1 +/- 14.1 to 29.6 +/- 14.7 mL, p = NS). Retrospective comparisons showed pig models to be a much closer approximation to the human anatomy because of a more similar thoracic cavity shape and heart orientation. These findings suggest that certain large animal models should not be used in research in which chest wall shape or cardiac orientation within the thoracic cavity may influence outcomes.

Right ventricular failure in patients requiring left ventricular assistance

Right ventricular failure may complicate isolated left ventricular assistance. In a series of 8 patients undergoing left ventricular assistance in postcardiotomy cardiogenic shock, right ventricular failure developed in 5, directly contributing to death in all cases despite initially satisfactory support. Difficulty in grafting a dominant right coronary artery was a common factor in all cases. Early consideration should be given to biventricular support under these circumstances.