Sub-total versus partial circulatory bypass of the left heart: a critical review

A number of systems for left heart bypass have been described for short, or long-term circulatory support in animals and in man. Critical to the interpretation of these restuls and to the design of new system is the proportion of left ventricular inflow destined for ejection which is diverted through the apparatus, to that expelled through the aortic valve, and the effect which this fraction might have on the failing heart and the rest of the body. It is the purpose of this communication to review the experimental and theoretical data in support of partial, as opposed to subtotal, left heart bypass.