Cardiac Size and Pulmonary Arteriography in Experimental Chronic Hypoxia

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Abstract
Guinea pigs submitted to simulated high altitude in low-pressure chambers developed right ventricular dilation that was followed by hypertrophy of the wall of that ventricle. These alterations are observed anatomically and in an increase in the size of the cardiac shadow. Injection of radiopaque material into the right ventricle has shown that dilation of the right ventricle is accompanied by dilation of the pulmonary artery and intrapulmonary arteries. After 2 weeks of exposure to simulated altitude, the right ventricle dilation subsides, but the dilation of the pulmonary artery system persists and becomes marked. The finer branches of the pulmonary artery system are not visualized after 1 week of exposure to simulated altitude. Microscopic observation of the injected lungs has determined that the experimental animals have no injection of the pulmonary capillary bed. This alteration may be secondary to partial obliteration of the pulmonary capillary bed, to a precapillary vaso-occlusion or vasoconstriction, to hematologic alterations or to any combination of these factors.