Wood, Earl H.

Indicator-dilution curves were recorded by oximeters at the ears and the right radial artery following the injection of Evans blue (T 1824) into the superior vena cava and pulmonary arteries of 37 subjects who had no evidence of cardiovascular disease. The variability and ranges of various time and concentration components of these dilution curves are presented. These values can be used as standards of reference in the interpretation of abnormal dilution curves. Some of the factors responsible for the variability of these values in healthy subjects are assessed and discussed.

Changes in pulmonary vascular (arteriolar) resistance were estimated in 58 patients with mitral stenosis following mitral valvotomy and during exercise. Evidence is presented that changes in "resistance" reflect active changes in the caliber of the vessels due to alteration in their smooth muscle tone, valvotomy being followed by a decrease in tone and exercise by an increase.

Anomalous connection of the right pulmonary veins to the superior vena cava associated with an interatrial communication in an unusually cephalad location has been diagnosed at cardiac catheterization in 8 patients. These patients had the clinical features seen in patients who have atrial septal defects in the region of the fossa ovalis. Differentiation was accomplished by (1) the roentgenographic position of the catheter in the right superior pulmonary vein, (2) demonstration of an abnormally high oxygen saturation of the blood in the superior vena cava, (3) the presence of a small right-to-left shunt from the superior vena cava and the absence of such a shunt from the inferior vena cava, and (4) demonstration of similar drainage of blood from the right superior pulmonary vein and superior vena cava. The syndrome is considered to be an anomaly of pulmonary venous development while the atrial septum forms normally.

Manifestations of left ventricular failure have been reported in the literature in some patients after surgical closure of atrial septal defects. The authors present their experience in their series of 85 cases and detailed hemodynamic measures in 16 patients.

In a limited number of subjects having hypoxemia related to congenital malformations of the heart, no evidence was obtained of a correlation between the degree of hypoxemia or the extent of the polycythemia and the systemic blood flow. The circulatory response to exercise was characterized by a greater increase in the arteriovenous oxygen difference than in the systemic blood flow. A syncopal reaction in one patient was preceded by a greatly increased systemic blood flow and a small arteriovenous oxygen difference.

Dye dilution and cardiac catheterization technics were used to study 36 patients with a central left-to-right shunt due to patent ductus arteriosus, atrial septal defect or ventricular septal defect. The configuration of dilution curves following injection of dye into an antecubital vein was similar in all instances. Principal abnormalities of the curve were a prolongation of its disappearance slope and a relative reduction in the peak concentration of dye. Quantitatively expressed, these abnormalities could be correlated with the magnitude of the left-to-right shunt. Curves of normal contour were observed following surgical closure of the ductus arteriosus, and in patients with isolated pulmonary stenosis.

Obstruction to pulmonary blood flow may occur in the pulmonic valve, in the infundibulum or in both. Cardiac catheterization aids in the determination of the site of obstruction. Criteria for the differentiation at operation of valvular and infundibular pulmonic stenosis are enumerated, and the usefulness of accurate pressure tracings during operation is emphasized. The accurate identification of the site or sites of obstruction to pulmonary blood flow is essential to proper surgical management. A correctly selected operation must be carried out in as complete a manner as possible.

Seven cases of patent ductus arteriosus with pulmonary hypertension and reversal of the usual direction of flow are described. Breathing of a low oxygen mixture either initiated or increased the reversed shunt, and breathing 100 per cent oxygen produced the reverse effect. Differences in oxygen saturation and dye-dilution curves recorded simultaneously from the radial and femoral arteries have allowed calculation of differences in the proportion of shunted blood flowing in these arteries and demonstrate that retrograde movement of blood in the aortic arch may occur.

Use of cuvette and earpiece oximeters facilitates the recording of the immediate dilution pattern of the dye T-1824 (Evans blue) in the arterial blood. In patients with venoarterial shunts the pattern of the dilution curves differs from normal. Quantitative analysis of such curves from patients with cyanotic congenital heart disease has been undertaken to establish the proportion of blood which bypassed the pulmonary circulation. The results obtained have been compared with estimates of the volume of the shunt from cardiac catheterization data and related to the arterial oxygen saturation.