The Flow of Blood Supplying the Cardiac Atria

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Abstract
Using the Starling heart-lung prepn., the left ant. auricular artery was perfused from the aorta of the prepn. Flow into the artery was measured qualitatively and quantitatively by the Gregg-Green differential pressure orifice meter. Analysis of the curves indicate that forward flows occur during ventricular systole and diastole, with momentary interruptions of inflow at the onset of ventricular systole and diastole. Inflow of blood into the auricular artery varied from 0.08 ml.-0.581 ml./cardiac cycle in different prepns. In order to study the effect of auricular distension upon atrial arterial inflow (as may occur in clinical heart failure), heart failure was induced in the heart-lung prepns. It was found that as heart failure occurred, and pressure within the left atrium rose, inflow into the atrial artery decreased. Usually a decrease of arterial inflow of 30-40% occurred as intra-atrial tension rose to 20 cms. water. Cardiac output and blood pressure were essentially unchanged. It is suggested that such auricular distension interferes with atrial blood supply and favors the development of abnormal auricular mechanisms.