Wood, Earl H.

Mitral valve function was assessed by roentgen videodensitometry. Mitral reflux was rare when single ventricular ectopic systoles were produced by electronic stimulation of the right or left ventricle at various times in the cardiac cycle. It was also rare during the compensatory pause after the ectopic systole or with the following postectopic systole. Recurrent ventricular ectopic systoles interposed once per cycle were associated with minor reflux when introduced in mid-cycle. Such extrasystoles occurred late enough in the cardiac cycle for the ventricle to relax after the primary systole and for the mitral valve to open before the extrasystole. The extrasystolic contractions were, however, weak and incapable of opening the aortic valve. When interposed early in the cardiac cycle, extrasystolic potentiation of the primary ventricular contraction occurred, and no or minimal mitral reflux was observed.

The status of 58 patients, 3 to 57 years of age, with ventricular septal defect and a marked increase in pulmonary vascular resistance (pulmonary obstructive disease) was determined 5 years or longer after diagnostic catheterization. Forty-six (80%) were alive 5 years after that study. The probability of living 5 years was 95% for patients aged 10 through 19 years and 56% for those 20 years of age or older. The dissimilarity of actuarial curves between these two groups is consistent with the hypothesis that pulmonary vascular obstructive disease develops under age 20. Calculated pulmonary resistance increased with age of patient on admission to the study, suggesting its progressive nature. Hemoptysis was rare under age 20, and its presence over this age indicated a poor prognosis. The most common causes of death were "sudden" or "unknown." Most surviving patients were gainfully employed or attending school without severe symptoms.

A method is described for detecting and quantitating small left-to-right shunts by recording continuously and simultaneously the changes in blood oxygen saturation at a systemic artery and at selected sites in the right heart chambers or great vessels produced by a few breaths of an inert gas such as helium or nitrogen. The advantages of this technic for detecting and quantitating left-to-right shunts are (1) the same instrument, namely, the cuvette oximeter, used to determine blood oxygen saturation and indicator-dilution curves in conjunction with routine diagnostic catheterization procedures, also is used to record the inert gas curves, (2) only one right heart catheter is needed, (3) the method is relatively simple, (4) the shunt can be quantitated, and (5) shunts of less than 10 per cent of pulmonary flow can be detected. It is concluded that the technic is of considerable practical value as a means of excluding the presence of or demonstrating and determining the magnitude of small left-to-right shunts.

Oxygen saturation of arterial and central venous blood was measured continuously during the Valsalva maneuver in patients with and without intracardiac defects. The majority of patients with atrial septal defects and patients with ventricular septal defects and high right ventricular pressure showed a sharp decrease in saturation of radial artery blood shortly after the maneuver. These changes were not recorded accurately by ear oximetry. The patients with shunts uniformly showed a rapid increase in saturation of pulmonary artery blood during the initial period of increased airway pressure. This effect was not observed in patients without shunts. These reactions may be of special diagnostic value under certain circumstances.

Survival following surgical correction of congenital cardiovascular defects is unlikely if pulmonary hypertension cannot be decreased significantly. Infusions of acetylcholine decreased pulmonary vascular resistance in 6 of 11 patients having pulmonary hypertension associated with atrial or ventricular septal defects. When the acetylcholine was combined with the breathing of oxygen, resistance decreased further. These findings are consistent with the theory that, at some stage, the pulmonary hypertension in cases of congenital heart disease is maintained at least in part by vasoconstriction and therefore is potentially reversible.

The present studies are concerned with the effect of high oxygen inhalation on patients with atrial septal defects. The problem of the amount of pulmonary vascular resistance and the relative contribution of irreversible structural changes and vascular tone may be of important prognostic significance in evaluation of such patients for cardiac surgery.