Measurement of transpleural collateral blood flow after pleurectomy.

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Since the report of Barrett and Daley in 1949 (2), pleurectomy has been advocated as a means of increasing pulmonary blood flow in patients with cyanotic congenital heart disease and low pulmonary artery pressure. In 1965, Helwig et al. (4) reported the case of a child with pseudotruncus arteriosus in whom pulmonary hypertension developed after a Potts shunt procedure. The pulmonary and systemic pressures were equalized, and the systemic arterial blood became unsaturated with reversal of the shunt. In order to increase pulmonary blood flow, they performed a right pleurectomy and instilled asbestos into the pleural space. Exercise tolerance increased immediately. Subsequent catheterization showed a decrease in hematocrit and an increase in oxygen saturation from 64 to 78 per cent. Arterio-graphically, intercostal blood was seen to drain into the pulmonary veins. The purpose of our study was to develop a radiographic and physiologic method of detecting and quantitating transpleural collateral blood flow in both normal animals and those with pulmonary artery hypertension before and after left parietal pleurectomy. Methods Mongrel dogs were anesthetized with pentobarbital, 32 mg/kg, and ventilated with a Harvard respirator. Each dog had right- and left-heart catheterization, during which pressures were measured by Statham transducers and recorded on a Sanborn multichannel recorder. We inserted a Cordis bronchial catheter via the femoral artery to catheterize selectively the right and left aortic intercostal arteries. Intercostal arteriograms were obtained after injection of 6 cc of 75 per cent Hypaque-M. Film-recording was made by a Sanchez-Perez film-changer at a rate of two exposures per second. For dye-dilution curves indocyanine-green was injected into the selective catheter, and the samples were obtained by a left atrial catheter and recorded by a Waters cuvette and densitometer. Nine normal dogs were examined. Three of the animals underwent left parietal pleurectomy, after which they were again catheterized. We then studied two pleurectomized dogs with elevated pulmonary artery pressure (mean pressures 20 mm Hg and 25 mm Hg) in the same manner. Pulmonary hypertension had been produced in these animals by repeated right ventricular injections of methyl-2-cyanoacrylate monomer in dimethyl sebecate, as described by Awe et al. (1). This substance rapidly polymerizes after injection and occludes the small pulmonary arterioles. Anatomy In the dog, the left intercostal arteries do not give rise to bronchial arteries. In almost every case, the bronchial vessels to both left and right lungs arise from the right aortic intercostals (6) (Fig. 1). A few left bronchial arteries may arise directly from the aorta.