Successful extended cardiopulmonary preservation in the autoperfused working heart-lung preparation

Myocardial and pulmonary preservation can be prolonged in the autoperfused working heart-lung (AWHL) preparation by metabolic substrate enhancement. However, uncontrolled pulmonary hypertension following denervation may result in extensive lung injury and occasional early failure of the preparation. To determine whether cardiopulmonary preservation could be reliably extended without development of pulmonary hypertension, six heart-lung blocks were harvested from calves, placed in a normothermic AWHL circuit, and studied. Continuous infusions of isoproterenol and dextrose/insulin were administered for the duration of the preparation. Thirteen heart-lung preparations received neither isoproterenol nor metabolic substrate and served as controls. Myocardial function was assessed by sonomicrometric techniques and pulmonary preservation was evaluated by extravascular lung water, arterial oxygenation on 100% inspired oxygen, static lung compliance, and pulmonary vascular resistance. Pulmonary hypertension developed in the control group and these animals did not survive beyond 7.5 hours. The addition of isoproterenol and metabolic substrate increased organ survival from 4.8 +/- 0.4 to 18.0 +/- 1.4 hours (p = 0.0001) and significantly reduced postexplant pulmonary vasoconstriction (p less than 0.05). Addition of isoproterenol and metabolic substrate to the AWHL model prolonged support of cardiorespiratory function and provided a reliable method for distant procurement in heart-lung transplantation.