Is cold, cardioplegic solution harmful to the lungs?

The effects of pulmonary flush with cold cardioplegic solution were investigated in 55 patients undergoing coronary artery bypass grafting. Extracorporeal circulation with bicaval cannulation was used in all cases, and single-dose cardioplegic solution was injected into the aortic root. In one of two randomly selected groups (n = 27) the cardioplegic solution was allowed to pass through the lungs and then evacuated via a left ventricular vent. In a second group (n = 28) the vent was first temporarily placed in the right atrium for evacuation of the cardioplegic solution, and the aortic root was vented later. Hemodynamic, metabolic, hematologic and radiographic changes were studied during the early postoperative period. No harmful effects of the pulmonary passage could be demonstrated. On the contrary, a protective effect was indicated, as the pulmonary vascular resistance index was reduced immediately and for 2 hours postoperatively. The ratio of left ventricular to right ventricular stroke work in the early postoperative period gave the same indication.