Cardiovascular adaptation to partial heart-lung bypass

Partial heart-lung bypass was performed in open-chest dogs, using the gravity arterial in-fusion technique. Arterial infusion pressure, venous suction and pressures in the left ventricle, aortic arch, and airways were phasically recorded. The mean flow in the aortic arch and the blood content of the extracorporeal circuit were continuously recorded. According to the height of the bag oxygenator above the heart level, partial heart-lung bypass resulted in a shift of blood either from the extracorporeal circuit into the animal or vice versa. When the body blood volume was increased by the bypass procedure, the cardiac output decreased only slightly. When the body blood volume was diminished by the bypass procedure, the cardiac output dropped markedly. It was found that when the systemic arterial pressure was maintained at approximately normal levels, independent of cardiac output, the change in cardiac output was proportional to the change in the body blood volume.

The present role of hypothermia in cardiac surgery

A survey of the current use of hypothermia during cardiac surgery has been presented. Hypothermia remains a simple and safe method to permit the surgical correction of uncomplicated atrial septal defects, although it is gradually being displaced by pump-oxygenators as they become better understood.

In conjunction with extracorporeal circulation moderate and extreme ("deep") hypothermia has been employed. Moderate hypothermia is without any known deleterious effects and may be of benefit by lowering perfusion rates and decreasing intracardiac aspiration of blood. The role of deep hypothermia with circulatory arrest remains uncertain. It is a condition associated with extreme physiologic alterations, many of which are poorly understood, and the safe limits are not yet clearly defined.

Finally, hypothermia remains a beneficial technic for neurologic injury following resuscitation from cardiac arrest. Recent evidence indicates that the mechanism of benefit involves considerably more than simple reduction of cerebral edema.

Diagnosis and surgical correction of congenital coronary artery-coronary sinus fistula

Congenital coronary arteriovenous fistula is easily confused with patent ductus arteriosus. An illustrative case is presented which emphasizes the special tests that are necessary to establish the diagnosis. Finally, the successful surgical correction of this abnormality is described.

COR TRIATRIATUM AS A PROBLEM OF ADULT HEART DISEASE

The occurrence of severe pulmonary venous obstruction due to the congenital anomaly known as cor triatriatum in a 19-year-old furniture mover is described. Relentless and massive hemoptysis led to pulmonary edema, and an attempt at surgical correction under unfavorable conditions was not successful.

Seven other cases of cor triatriatum in adults are reviewed. The hemodynamic abnormalities closely resemble mitral stenosis, except that pressures in the true left atrium were normal in the presence of elevated pulmonary capillary pressures. The availability of flow across the obstructing membrane during systole as well as diastole is probably the major element in the surprisingly good tolerance of severe degrees of anatomic obstruction for long periods of time. Slow increase in the degree of obstruction could also be a factor.

The clinical picture in these patients very closely resembles mitral stenosis. Hemoptysis appeared to be more frequent in cor triatriatum. Features suggestive of the correct diagnosis would include the absence of an opening snap, the absence of a typical murmur of mitral stenosis, regular rhythm, and lesser evidence of left atrial enlargement in the presence of obvious pulmonary hypertension. Five of these patients have undergone successful correction of their disease by operation.

Representative films from the first known angiograms in this condition in an adult are reproduced and discussed.