Cardiogenic shock (CGS) results in inadequate end organ perfusion and is associated with high mortality. For patients presenting with CGS following myocardial infarction (MI), reported rates of mortality range between 55% and 80% despite aggressive pharmacological therapy and use of the intra-aortic balloon pump (IABP). Patients with CGS due to ventricular septal defect (VSD) or ventricular rupture following MI have mortality rates approaching 100%. Accordingly, a minimally invasive therapeutic intervention beyond the capabilities of the IABP is needed to enhance cardiac output and organ perfusion for treating these patients as a bridge to recovery of function or to definitive therapy.
In addition, there is a great need for a device that can be used to support patients who are undergoing high risk procedures such as angioplasty or bypass surgery who may not tolerate cardiopulmonary bypass. Currently, many such patients are denied the procedure due to inordinate risk. Prior attempts to develop a minimally invasive system for this purpose have been fraught with difficulty in requiring general anesthesia and use of a full cardiopulmonary bypass pump team.
The Texas Heart Institute (THI) has used the TandemHeart™ percutaneous transseptal ventricular assistance (PTVA) with some success. It is a circulatory support system which may address these needs. The device is placed under fluoroscopic guidance in a cardiac catheterization laboratory and is designed to unload the left ventricle while providing adequate cardiac output and organ perfusion. It can be placed in a patient who is under conscious sedation and requires no incisions.This technology is a step up from IAPB support and can provide temporary circulatory support of 3-3.5L/min.
At the THI, patients were either weaned from TandemHeart support, transferred to another therapy (e.g. percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG)), or expired during support. Patients were weaned from the device when they remained clinically stable and able to maintain CI>2.2L/min/M2, MAP>70mmHg and PCWP<18mmHg without inotropic support during stepwise decreases of pump speed to a minimum of 0.5L/min for 1-2 hours. In this experience of 10 patients, there was only one device-related death, and the remaining patients were supported to PCI or CABG, or weaned.