Katherine H. Halloran

Bronchial and Arterial Anomalies with Drainage of the Right Lung into the Inferior Vena Cava

Three cases of anomalous pulmonary venous return to the inferior vena cava are presented and 18 previously reported cases are also analyzed. The clinical, radiographic, circulatory and pulmonary function, and anatomic features are carefully detailed. In particular, associated vascular and bronchial anomalies in the lungs were found by preparation of vinylite casts of the pulmonary vessels and bronchial casts; they are of great significance in planning and executing surgical therapy.

Anomalous origin of the left coronary artery from the pulmonary artery: A clinical spectrum

Abstract Five cases of an anomalous left coronary artery originating from the pulmonary artery have been presented. These illustrate different phases in the clinical spectrum of this anomaly. Two patients who presented with congestive failure and classic signs of myocardial infarction in early infancy underwent surgical ligation of the anomalous vessel. One survived and one died postoperatively, possibly with secondary residual mitral insufficiency as a contributory factor. Congestive failure and a clinical picture of mitral insufficiency developed in one other child at 1 year of age, and she died 10 months later with unremitting failure. Two children who were in failure in infancy, 1 with evidence of myocardial ischemia, have had a benign clinical course since that time. The clinical course and appropriate management of a patient would appear to depend upon the degree of development of the coronary collateral circulation. Some of the factors influencing the adequacy of these collateral vessels are postulated, including the presence of collateral channels at birth and the stimulation of new vessels by ischemia as the pulmonary arterial pressure falls. In those patients in whom the collateral circulation is adequate enough to allow survival, the clinical picture may be dominated by mitral regurgitation resulting from endocardial fibrosis with dilatation of the mitral valve ring.

A STUDY OF VENTRICULAR SEPTAL DEFECT ASSOCIATED WITH AORTIC INSUFFICIENCY.

Abstract Clinical, electrocardiographic, radiographic, and hemodynamic findings in 12 children with the combination of a ventricular septal defect and aortic insufficiency are presented. The left-to-right shunt was determined to be small or moderate in all, and significant aortic insufficiency was documented by aortography in 11 patients. Clinical indication of aortic insufficiency as manifested by an aortic diastolic murmur first appeared at an average age of 6 years in 7 patients, with concomitant widening of the pulse pressure in 4. Progressive left ventricular hypertrophy was noted electrocardiographically, with progressive cardiac hypertrophy and aortic dilatation on x-ray examination in 2 patients. Progression of the hemodynamic disability does not appear to be common in childhood, however.

Influence of Sympathetic Nerve Stimulation on Ventricular Function in the Newborn Lamb

Cardiac responses to supramaximal electrical stimulation of postganglionic sympathetic nerve fibers were studied in 17 lambs, 10 hours to 3 days of age. In all lambs left ventricular contractility increased within 3 seconds and was unaltered by atropine, ganglionic blockade, or nerve sectioning proximal to the stimulating electrodes but was abolished by beta-receptor blockade. The responses were repeatedly demonstrated in two lambs subjected to bilateral adrenalectomy. Acidemia (pH 6.9) produced by lactic acid infusion failed to diminish the inotropic responses. Intravenous or leftatrial injections of tyramine produced chronotropic and inotropic responses comparable to sympathetic nerve stimulation. Glucagon, 50 to 200 µg/kg, failed to elicit cardiac responses in lambs from 1 to 60 days of age. It is concluded that sympathetic neural mechanisms may strongly influence myocardial contractility in the newborn lamb and that these responses are independent of adrenal medullary release of catecholamines. These findings further suggest that the lamb possesses a myocardial adenyl cyclase system that responds only to catecholamines and may be blocked with propranolol.

Genetic counseling for congenital heart disease

The genetic knowledge of parents of children with congenital heart disease, who had received genetic counseling, was compared with that of a control noncounseled group attending the same cardiac clinic. A follow-up questionnaire showed that both groups had excellent knowledge of the nature of their childrens heart lesions. The counseled group had significantly more accurate knowledge of their recurrence risks. Inasmuch as the reproductive attitudes of some of these parents were found to be influenced by genetic information, parents of children with CHD should be given a better understanding of recurrence risks for CHD than many of them possess.

Superiorly oriented electrocardiographic axis in infants with the rubella syndrome

Abstract An unusual superiorly oriented mean electrical axis has been described in 12 of a series of 23 infants with congenital heart disease associated with the rubella syndrome. The majority of infants had a patent ductus arteriosus or peripheral pulmonic stenosis. The electrical axis did not correlate with the anatomic diagnosis of ventricular hypertrophy, and the possibility that this axis may represent a conduction disturbance is discussed.

Influence of Norepinephrine and Digitalis on Myocardial Oxygen Consumption in the Newborn Lamb

The relationships between cardiac performance and oxygen usage were explored in 19 newborn lambs (5 hours to 8 days old), and the influence of inotropic stimulation was studied. A preparation was developed to measure coronary sinus flow and myocardial oxygen consumption (MVo2) under controlled hemodynamic conditions. Using a gelatin injection technique, we determined that more than 90% of the measured sinus flow originated from left heart tissue; less than 10% was derived from right ventricular myocardium. Changes in contractility were produced by intravenous infusion of norepinephrine or acetylstrophanthidin. Norepinephrine (1–2.4 μg/min kg−1) or acetylstrophanthidin (5 μg/min kg−1) produced increases in the maximal rate of rise of left ventricular pressure and large reductions in left ventricular enddiastolic pressure, but the changes in MVo2 in lambs with constant aortic blood pressure, cardiac output, and heart rate were minimal. Ventricular function curves demonstrated a significant relationship between end-diastolic pressure and MVo2 (P < 0.01). For a given left ventricular end-diastolic pressure, MVo2 was approximately 3 ml/min 100 g−1 left ventricle greater during the infusion of norepinephrine. Therefore, net changes in MVo2 with inotropic stimulation represented a balance between reciprocal changes in diastolic pressure (and volume) and contractility. The enhanced oxygen cost of increased contractility might be masked by a reduction in heart size (reduced wall stress). Ventricular function was reduced below initial control values following the infusion of norepinephrine in 3 lambs. This reduction correlated with a concomitant reduction in MVo2 and percent extraction but not with a reduction in flow. Lambs that did not show mechanical depression demonstrated no reduction in MVo2. These findings suggest a metabolic basis for catechol dependence which might have special importance for the newborn lamb with its incompletely developed catechol enzyme systems.

Relation between acute changes in pH and PCO2 and inotropic responses to acetyl strophanthidin

Abstract The effects of acutely induced hypercapnic or lactic acidemia on the inotropic responses to acetyl strophanthidin were studied in adult cats. Beta adrenergic blockade was produced with propranolol to eliminate sympathetic influences on the heart. In control animals significant increases in stroke volume, mean ejection rate and rate of rise of left ventricular pressure (dPdt) were shown after infusion of acetyl strophanthidin, 15 μg/kg. Similar increases were demonstrated in cats with lactic acidemia (pH 7.0) or hypercapnic acidemia (PCO 2 60 mm Hg). The responses of cats with low pH or high PCO 2 values did not differ significantly within the 2 groups or by comparison with control responses. These results demonstrate (1) that digitalis is effective in producing significant inotropic responses even under these altered metabolic conditions, and (2) that propranolol does not inhibit these responses.

Cardiac Responses to Sympathetic and Vagal Stimulation in the Newborn Lamb During Acidosis and Hypoxia

Heart rate (HR) and left ventricular co ntractility (VC) responses to sympathetic and vagal nerve stimulation were assessed in 15 lambs from < 1 to 3 days of during lactic acidemia, hypercapnia and hypoxemia. These were compared with responses under control conditions. In all experiments supramaximal electrical stimulation of the left inferior cardiac sympathetic nerve produced large increases of VC as measured by the dP/dt max from a given end-diastolic pressure (LVEDP) when HR, mean aortic pressure and cardiac output (Medicon) were held constant. With a pH of 7.39 the dp/dt max increased from 3,000 (±155 SE) to 4,244 (±147 SE) mm Hg/sec during stimulation, while the LVEDP fell from 7.3 (±0.73 SE) to 5.8 (±0.79). During acidemia the increase (1,310±159 SE) was unchanged. With hypercapnia (PCO2 69 mm Hg) the responses were less (840 mm Hg/sec) than with low PCO2 (1,300 mm Hg/sec, p<0.01). Responses during hypoxemia (PO2 33 mm Hg) were indentical to those with normal PO2. Cardiac slowing in response to stimulation of the right distal vagus N was measured at several frequencies (F) from 1-15/sec, duration 5msec, and 10-15 V. slowing was a function of F, but was unaltered by changes of PO2, PCO2 of pH up to an F of 10/sec. At F 15 the bradycardia was often enhanced by hypercapnia. It is co ncluded that hypoxemia and lactic acidemia do not alter adrenergic (A) or cholinergic (C) transmission, but that hypercapnic acidosis may reduce A, and enhance C during maximal stimulation. This suggests a mechanism whereby autonomic control of the heart may be altered in neonatal asphyxia.