Counterpulsation From the Skeletal Muscle Ventricle and the Intraaortic Balloon Pump in the Normal and Failing Circulations

Abstract

Background— The intra-aortic balloon pump (IABP) is the device that is in most common use to provide cardiovascular support. A skeletal muscle ventricle (SMV) was configured to produce counterpulsation in the thoracic aorta similar to that obtained with an IABP. The hemodynamic effects of an IABP and a SMV in the same animal and in both normal and failing circulations were assessed. Methods and Results— SMVs were connected to and IABPs were placed in the thoracic aorta of 12 anesthetized pigs. Hemodynamic parameters during the IABP- or the SMV-assisted beat were compared with those during the preassist beat. Acute heart failure was induced in 6 of the pigs by snaring the left anterior descending coronary artery (LAD). The hemodynamic effects of the IABP and the SMV were then reassessed. In the assisted cycles, SMV activation increased the mean aortic diastolic pressure (MADP) by 26.5±3.5%, the mean diastolic LAD flow by 48.4±7.2%, and endocardial viability ratio (EVR) by 31.6±3.8% ( P <0.0001). In the same animals, IABP assist increased MADP by 19.8±2.3%, mean diastolic LAD flow by 37.2±3.9%, and EVR by 21.4±3.0% ( P <0.0001). Under acute heart failure conditions, both SMV and IABP assist significantly increased MADP, mean diastolic LAD flow, and EVR. Conclusions— In both the normal and failing circulations, the SMV was an effective counterpulsator, providing cardiac assist that was at least equal to that available from an IABP. The SMV may therefore provide the proven benefits of an IABP in ambulant patients.