Decompression of the left ventricle in the recovery period during myocardial revascularization

Effective left heart decompression is essential for the reduction of myocardial oxygen consumption during recovery from an induced ischemic insult. During the early postischemic recovery phase of patients undergoing aorto-coronary bypass surgery, left ventricular, left atrial and aortic pressures were measured in non-vented hearts and in 2 types of left ventricular decompression. The following findings were made: Total cardiopulmonary bypass with effective decompression of the left ventricle decreases peak systolic left ventricular pressure, thereby reducing oxygen consumption of the myocardium. In this way adequate conditions are provided for recovery of the myocardium after unclamping of the aorta. The best method for decompression appears to be the placing of a large-lumen cannula in the left ventricle and allowing the blood to pour freely from the vent. The zero or near zero left ventricular filling pressure achieved with total cardiopulmonary bypass but without ventricular decompression does not prevent the chamber from producing isometric pressure work with peak systolic pressure reaching 80 to 90 torr. The hazard of air embolism may be reduced by precautionary measures. Left atrial monitoring permits recognition of pressure decreases to negative values. Active suction of the blood from the left ventricle is dangerous and should be avoided.