Abstract
Summary
1. The immediate cardiodynamic effects of uncomplicated tricuspid insufficiency were studied in dogs to elucidate the manner by which equilibrium between right and left ventricular output is maintained.
2. Pressure pulses were recorded from the right auricle, right ventricle, pulmonary artery and) aorta by calibrated optical manometers.
3. As in mitral insufficiency, regurgitation occurs chieflly during ventricular ejection. However, except during late systole and early diastole, auricular pressure is not greatly elevated. The increased venous pressure found in clinical cases is apparently due to an increased blood volume or to the mechanisms associated with compensation or other cardiac lesions.
4. Comparison of pulmonary and aortic pressure pulses reveals that while the mechanism of left ventricular ejection is unchanged, that of the right is altered. The major portion of the stroke volume is ejected early in systole when regurgitation is less marked. The pulmonary pressure falls rapidly after reaching its peak, due to failing ventricular output later in systole when regurgitation becomes more pronounced. These changes are illustrated by theoretical volume curves of the two ventricles.
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