Use of the pulmonary artery for left ventricular venting during cardiac operations

Data relating to the hemodynamic efficaciousness and mechanism of action of a pulmonary artery catheter or vent used for left ventricular venting during cardiac operations are presented. The pulmonary artery vent is a plastic sump catheter that is introduced into the main pulmonary artery through a purse-string suture and connected via a roller pump to the venous reservoir of the heart-lung perfusion machine. Placement and removal require only a few minutes. The pulmonary artery vent retrieved 85% of a ^99mtechnetium-labeled solution placed in the left atrium during aortic cross-clamping, and there was no detectable radioactivity in peripheral or aortic root blood samples. Pulmonary artery vent return during cardiopulmonary bypass in 10 patients undergoing coronary artery bypass averaged 12.5 L. The effectiveness of left ventricular decompression was evaluated in 20 patients also undergoing bypass grafting. Use of the pulmonary artery vent consistently and significantly decreased left heart pressures, compared to the control situation with the vent off, with the aortic cross-clamp applied, and in both the fibrillating and beating heart in the early postischemic reperfusion period. We reached the following conclusions: (1) The pulmonary artery vent withdraws left heart blood via the pulmonary vasculature, in addition to returning right heart spillover and retrieving bronchial flow. (2) Left heart pressures are reduced to levels which reduce oxygen demands and preserve endocardial perfusion, therefore protecting myocardium, during fibrillation and during coronary reperfusion of the beating heart. (3) Because of its effectiveness and safety, especially the impossibility of introducing air into the left ventricle, the pulmonary artery vent is recommended for routine left ventricular venting.