In situ cooling in a lung hilar clamping model of ischemia-reperfusion injury.

Experimental models for studying transplantation have up to now been unable to isolate reperfusion injury with minimal surgical manipulation and without the interference of graft rejection. Six pigs were subjected to left hilum preparation only (control group), and eight pigs were subjected to left hilum preparation plus in situ cooling ischemia and reperfusion of the lung (experimental group). The hilum was dissected free from other tissues in both groups. Lung preservation was achieved by antegrade flush perfusion via the left pulmonary artery. Pulmonary veins were clamped at the left atrium and a vent was created. The left main bronchus was clamped. Lung temperature was maintained at 4 degrees -8 degrees C, while core temperature was kept at 38 degrees C. After 3 hrs of cold ischemia the clamps were removed and the lung was reperfused. Elevated pulmonary vascular resistance and local and systemic aspects of ischemia-reperfusion syndrome were consistently reproduced. This large-animal model of in situ unilateral lung cold ischemia with warm reperfusion proved to be very reliable in reproducing all aspects of ischemia-reperfusion injury. It excludes the interference of rejection and extensive surgical manipulation. We therefore propose its use in experimental studies investigating pharmaceutical or cooling modifications affecting lung ischemia-reperfusion outcomes.

Anastomoses between bronchial and coronary circulation in a porcine model: computed tomographic and angiographic demonstration.

INTRODUCTION: Although the importance of the bronchial arteries is evident in modern day thoracic surgery, the significance of their communications with coronary arteries has yet to be appreciated, especially in cases of heart-lung transplantation and aortic aneurysm repair. We conducted a study to demonstrate the coronary-bronchial anastomotic routes in a porcine model using angiography and computed tomography. METHODS: Six young female white pigs were used. The heart and lungs were removed en bloc, including the lower trachea and oesophagus. Digital subtraction angiography of the bronchial circulation and spiral computed tomography scan were performed in a three-phase study before and after administration of contrast medium. This was achieved by infusion either into the cannulated bronchial artery or into the aortic root. Macroscopic evaluation was carried out using latex infusion into the bronchial or coronary circulation. RESULTS: We demonstrated communications between the bronchial and coronary systems in 5 of 6 subjects. This communication was located at the left atrial wall and the posterior and anterior wall of the left ventricle. In one case there were further anastomoses around the right atrial wall. CONCLUSIONS: There were communications between the left coronary arteries and the bronchial arteries in the majority of cases. Digital subtraction angiography and spiral computer tomography scan can demonstrate these communications directly and indirectly by measurements of contrast enhancement within the heart wall. Our study emphasises the importance of the bronchial arteries in cases of heart-lung transplantation and repair of thoracic aortic aneurysms.