Circulatory By-Pass of the Right Heart. I. Preliminary Observations on the Direct Delivery of Vena Caval Blood into the Pulmonary Arterial Circulation. Azygos Vein-Pulmonary Artery Shunt **

The surgical treatment of certain congenital anomalies of the right side of the heart characterized by malor non-function of the right auricle or right ventricle or both may depend on the possibility of the direct delivery of blood from the vena cava into the pulmonary arterial circulation.t The immediate and ultimate success of this procedure would depend on the volume of blood flow through the pulmonary artery. As stated by Dexter, et al.,' "The volume of blood flowing through the pulmonary artery per unit of time is dependent upon the pressure in the pulmonary artery, the resistance to blood flow offered by the pulmonary vasculature, and the ability of the left side of the heart to handle the volume of blood which it receives." On the basis of studies by these investigators on the pulmonary artery pressure in normal adult humans, a mean pressure of about 13 to 17 millimeters of mercury would be sufficient to propel a normal blood flow through the pulmonary artery at rest. A venous pressure of this magnitude would, acting alone, usually be insufficient to produce peripheral edema.' Prolonged increased venous pressure may, however, lead to varicosities and the development of a collateral venous circulation.