Benjamin M. Lewis

Factors regulating pulmonary “capillary” pressure in mitral stenosis. IV☆

Abstract 1. 1. Pulmonary edema occurred at rest in six patients and during exercise in three other patients with severe mitral stenosis during cardiac catheterization. 2. 2. Pulmonary “capillary” pressure was 32 mm. Hg or higher in all nine patients. 3. 3. Pulmonary “capillary” pressure, actually an index of left atrial pressure, was elevated to such high levels in order to maintain blood flow through the mitral valve. 4. 4. Factors which resulted in an increased mitral valve flow rate, thus requiring an elevation in pulmonary “capillary” pressure, were (a) increased cardiac output and (b) decreased diastolic filling period. The latter was decreased by increases in (1) heart rate and (2) duration of ventricular systole. 5. 5. The degree of anatomic mitral stenosis affected the degree of pulmonary “capillary” pressure rise in exponential fashion. 6. 6. The mechanism of elevation of pulmonary “capillary” pressure was believed to be a momentary imbalance in ventricular outputs such that pulmonary blood volume and pressure were increased. 7. 7. It has been demonstrated that in patients with mitral stenosis, a normal cardiac output can be delivered only at the expense of high pulmonary “capillary” pressure. 8. 8. The role of tachycardia, even of a mild degree, in producing or aggravating symptoms of pulmonary edema is emphasized.

Transposition of the aorta and levoposition of the pulmonary artery.

Abstract 1. 1. A case of the Taussig-Bing syndrome (transposition of the aorta with levoposition of the pulmonary artery) definitely diagnosed in life is reported. 2. 2. From a review of the literature, it is concluded that this syndrome can be separated from transposition of the great vessels with ventricular septal defect only by angiocardiography and then only in favorable circumstances.