The Journal of thoracic and cardiovascular surgery
-
J. Thorac. Cardiovasc. Surg. · Sep 1993
Altered pulmonary microvascular reactivity after total cardiopulmonary bypass.
Pulmonary vascular resistance is frequently elevated after cardiac operations in which cardiopulmonary bypass is used. In our study of the possible contribution of altered pulmonary microvascular reactivity to this condition, sheep were heparinized, cannulated via the aorta and right atrium, and placed on total cardiopulmonary bypass. After 90 minutes of total cardiopulmonary bypass and pulmonary arterial occlusion, the sheep were removed from cardiopulmonary bypass, and their lungs were perfused normally for 60 minutes. ⋯ Endothelium-independent responses to sodium nitroprusside and U46619 and dilation responses to adenosine were not altered after cardiopulmonary bypass. Extracorporeal circulation with continued pulmonary arterial perfusion (right heart bypass group) had no effect on microvascular responses. In conclusion, total cardiopulmonary bypass with associated reduced pulmonary perfusion causes significant alterations of endothelium-dependent pulmonary microvascular responses because of the increased release of a constrictor prostanoid substance and possibly because of reduced release of endothelium-derived relaxing factor.
-
J. Thorac. Cardiovasc. Surg. · Sep 1993
Pulmonary vascular disease and operative indications in complete atrioventricular canal defect in early infancy.
Pulmonary vascular disease was morphometrically analyzed in 67 patients (mean age, 19 months) with isolated complete atrioventricular canal defect. Complete obstruction of the small pulmonary arterial lumen resulting from acute fibrous proliferation and atrophy of the peripheral arterial media, which were considered absolute operative contraindications, were characteristic in six patients with Down's syndrome. Morphometric analysis of medial thickness revealed that thinning of the media of the small pulmonary arteries is generally observed at around 6 months of age in patients with complete atrioventricular canal defect and that the media in patients who have complete atrioventricular canal defect and Down's syndrome was thinner than that in such patients without Down's syndrome. ⋯ Excluding patients with absolute operative contraindications, the scores of the index of pulmonary vascular disease in operative survivors were below 2.0 and death occurred when scores were more than 2.2. The pulmonary vascular resistances measured in room air and by the oxygen inhalation and tolazoline tests in patients with operative contraindications were more than 7.3, 3.8, and 6.6 units.m2, respectively. We thus conclude that lung biopsy should be undertaken for patients in whom pulmonary vascular resistance is beyond these values to determine the appropriateness of surgical intervention.