This clenbuterol-supported dynamic training provides powerful SMVs that may have important clinical implications for the treatment of end-stage heart failure by muscular blood pumps.

The combination of electrical conditioning with dynamic training of the SMVs resulted in a strong muscle pump that did not develop fatigue. Dynamic training for skeletal muscle represents a new and promising method for providing powerful autologous cardiac assist.

Skeletal muscle ventricles used for cardiac assistance were trained dynamically by shifting volume within an elastic training device. To optimize this dynamic training that is by variation of stimulation patterns and application of drugs, methods for stroke volume and energy evaluation were required. A volume shift induced by a muscle contraction resulted in a pressure rise in the training device. Stroke volume was calculated by relating the pressure difference of a muscle contraction to the device's compliance. For validation of the calculated stroke volume, a mock system was built to simulate muscle contractions under various conditions. The stroke volume measured independently and calculated by means of the pressure rise inside the training device, showed an approximately one-to-one relation (R=0.996). Calculation of delivered energy from skeletal muscle ventricles thereby became possible. This method offers a simple, reliable and practical procedure to quantify the dynamic training of skeletal muscle ventricles for use in cardiac assistance.

Experimental valveless muscular blood pumps (biomechanical hearts) in goats can pump more than 1 L.min(-1), but due to a high pendulum volume, no significant flow contribution to the circulation is gained. Thus valved and valveless biomechanical hearts were compared for efficacy. Heart failure was induced in 5 adult Bore goats by repeated intracoronary embolization. A valved and balloon-equipped pumping chamber was integrated into the descending aorta, simulating standard biomechanical circulatory support. The valveless biomechanical heart supported a failing heart with a baseline cardiac output of 2,670 +/- 710 mL.min(-1) by contributing additional flow of 113 +/- 37 mL.min(-1). The biomechanical heart model incorporating an outlet valve offered an additional 304 +/- 126 mL.min(-1), and the use of 2 valves significantly enhanced pulmonary blood flow by 1,235 +/- 526 mL.min(-1). The use of 2 valves in biomechanical hearts seems to be essential to achieve adequate circulatory support. Double-valved biomechanical hearts driven by an appropriate skeletal muscle ventricle may contribute to the therapy of heart failure.

Tip design of aortic cannulae and the orientation of its jet stream are potential sources of remarkable imbalance of arch vessel perfusion especially with single jet stream cannulae. These effects are more pronounced with single jet stream cannulae. These results may have important clinical implications regarding perfusion of arch vessels during extracorporeal circulation.