The TandemHeart percutaneous ventricular assist device can be used to support patients in cardiogenic shock (until cardiac recovery occurs or as a bridge to definitive therapy) or as a temporary application during high-risk coronary interventions. The TandemHeart is a left atrial-to-femoral artery bypass system comprising a transseptal cannula, arterial cannulae, and a centrifugal blood pump. The pump can deliver flow rates up to 4.0 L/min at a maximum speed of 7500 rpm. From May 2003 through May 2005, the TandemHeart was used to support 18 patients (11 in cardiogenic shock and 7 undergoing high-risk percutaneous transluminal coronary angioplasty). The patients in cardiogenic shock were supported for a mean of 88.8 +/- 74.3 hours (range, 4-264 hr) at a mean pump flow rate of 2.87 +/- 0.56 L/min (range, 1.8-3.5 L/min). The mean cardiac index improved from 1.57 +/- 0.31 L/min/m2 before support to 2.60 +/- 0.34 L/min/m2 during support. The mean duration of support for the high-risk percutaneous transluminal coronary angioplasty patients was 5.5 +/- 8.3 hours (range, 1-24 hr). The mean flow rate was 2.42 +/- 0.55 L/min (range, 1.5-3.0 L/ min). The overall 30-day survival rate was 61%. In our experience, the TandemHeart device was easy to insert and provided a means either to cardiac recovery or to continued support with an implantable left ventricular assist device.