HAeMODYNAMIC EFFECTS OF SEVERE AORTIC REGURGITATION

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Abstract
Eight patients with severe aortic regurgitation are described who showed equalization of left ventricular and aortic pressure in diastole. In one, this occurred at mid-diastole and in 2 others at end-diastole. The remaining 5 showed this phenomenon only during long diastolic pauses following a premature systole. Aortic pressures fell rapidly due to reflux into the ventricle. Left ventricular end-diastolic pressures rose greatly due to increased diastolic volume loads and reduced ventricular distensi-bility. Pressures at equalization were 33 to 55 mm. Hg. Left atrial pressures were measured in 3 patients who all showed raised mean pressures and large "a" waves. In one, atrial contraction raised left ventricular end-diastolic pressure substantially above mean left atrial pressure. In one, atrial contraction occurred after mitral valve closure. Premature mitral valve closure occurred in one patient after one-third of the time normally available for ventricular diastolic filling. This resulted from severe aortic reflux combined with rapidly diminishing ventricular distensibility after early diastole. It was thought to limit the degree of reflux and enhance myocardial contraction. It protected the lungs from the extreme rise in left ventricular diastolic pressure, but exposed them to the effects of atrial contraction against the closed mitral valve.