Donald E. Cassels

Lack of connection between the atria and the more peripheral conduction system in congenital atrioventricular block

Abstract The hearts in 7 cases of congenital atrioventricular (A-V) block due to absence of or diminution in the connection between the atria and the A-V node or bundle (in the absence of the A-V node) were studied by serial section. In 3 cases the A-V node was present; it was buried in the central fibrous body and the atrioventricular portion of the pars membranacea. In 3 cases the A-V node was absent, but the more peripheral portion of the conduction system was intact. In all of these cases, the block was shown to be supraventricular by electrocardiogram. In the seventh case, the A-V node was absent and the A-V bundle and right bundle branch were also defective. It is suggested that this disease is due to a malformation of the central fibrous body during the absorption of the bulbus, which causes the obliteration of the atrial muscular connections to the A-V node and may also injure the conduction system.

THE POSITION OF THE OXYGEN DISSOCIATION CURVE OF THE BLOOD IN NORMAL CHILDREN AND ADULTS

Oxyhemoglobin dissociation curves were determined in normal children and adults as a preliminary to a study of such curves in patients with cyanotic congenital heart disease. A comparison of the curves of normal children with those of normal adults showed that the dissociation curves of children tend to lie to the right of those of the adult. In order to confirm this observation, the study was extended to include more cases and a wide range of ages. Thi-s report presents the results of the study. The report consists of a comparison between the positions of the oxyhemoglobin dissociation curves of the child and the adult in a group of 21 children two to ten years of age and 22 adults 21 to 45 years of age. In addition, it includes oxygen dissociation data for six newborn infants less than one day old, for a group of 15 older infants varying in age from 11 days to two years, and for a group of nine pre-adolescents, adolescents and post-adolescents from 11 to 20 years of age. The older infants were included in order to determine whether the slight shift of the curve to the right in childhood is greater in infancy. The older children were studied in the hope of determining the approximate age at which the leftward shift to the normal adult position occurs.

Dye Dilution Curves and Cardiac Output in Newborn Infants

The pattern of dye dilution curves and the cardiac output was studied in 29 healthy newborn infants during the first 26 hours of life by the method of Wood and his associates. Thirty-six per cent of all infants studied had curves of normal contour which occurred mostly in infants older than 15 hours. Infants younger than 15 hours tended to have curves of abnormal shape. These were either diphasic or had the appearance of curves associated with left-to-right shunts and were probably caused by a patent ductus arteriosus. The mean cardiac output was 540 cc. per minute.

THE POSITION OF THE OXYGEN DISSOCIATION CURVE OF THE BLOOD IN CYANOTIC CONGENITAL HEART DISEASE

The similarity of the blood picture in patients with cyanotic congenital heart disease and in residents at high altitudes suggested the investigation of the position of the oxygen dissociation curve as a possible compensatory mechanism for reducing tissue hypoxia. In studies by the International High Altitude Expedition to Chile in 1935, Keys, Hall and Barron (1) found a small and questionably significant displacement of the curve to the right in the blood of residents at 5.34 km., in contrast to a displacement to the left as reported by Barcroft and his collaborators (2) from observations at 4.33 km. in 1922. With one exception, other expeditions to higher altitudes have found no changes in the position of the dissociation curve with decreasing barometric pressures (3, 4). However, a displacement of the curve to the right was given added confirmation by the finding by Aste-Salazar and Hurtado (5) that ten of the 12 native residents at altitudes of 4.5 km. had PO2 values at 50 per cent saturation which were higher than the corresponding mean level for a group of residents at sea level.2 Such a displacement, even though slight, would have advantage in that it would increase the capacity for oxygen transport by decreasing the venous saturation level for a given PO2 level. The present report describes the results of a study of the positions of the dissociation curve of the blood in 29 patients with cyanotic congenital heart disease 8 as compared with those of 43 normal individuals.

Friedreich's ataxia associated with idiopathic hypertrophic subaortic stenosis

Abstract Friedreichs ataxia and idiopathic hypertrophic subaortic stenosis (IHSS), both diseases of unknown etiology, both result in hypertrophy and degenerative changes of the myocardium. Both diseases lead to nearly identical electrocardiographic changes. We report a patient who developed classical signs of Friedreichs ataxia several years after he was found to have moderately severe IHSS. This observation prompted a hemodynamic study of five other patients with Friedreichs ataxia in search of a more common association and thus a possible etiological link between the two diseases. Cardiac catheterization was performed under local anesthesia. Catheters were inserted into the right ventricle, the pulmonary artery, the left ventricle, and the aorta. Isuprel infusion up to 6 μg per minute was used in an attempt to induce an abnormal pressure gradient across the right or left ventricular outflow tract. Both right and left ventricular cineangiograms were obtained for evaluation of ventricular kinetics and wall thickness. Right and left heart pressures were normal at rest in all patients. During Isuprel infusion a 40 mm. pressure gradient was induced across the left ventricular outflow tract in only one patient. A second patient developed a 16 mm. gradient across the right ventricular outflow tract. All patients had low normal cardiac outputs. The angiograms demonstrated increased left ventricular wall thickness in all patients. It is concluded that systolic left and/or right ventricular out-flow tract obstruction is only infrequently present in Friedreichs ataxia and is mild in degree. An etiological link between Friedreichs ataxia and IHSS is not known at the present but may possibly exist and should be investigated.

The lung volume and its subdivisions in normal boys 10-17 years of age.

disease. Because the absolute values obtained have no meaning for children varying so greatly in size, except as they can be referred to some standard of reference, such as height, weight, and other measurements of body size, the results were analyzed by statistical methods in order to determine the relation of the lung volume and its subdivisions to various physical characteristics of the child. These relationships were then expressed in the form of regression equations which can be used to predict the lung volume and its subdivisions for a given individual and, by means of the standard error of estimate, can give a measure of the amount of variation that may be expected in the normal child. Of the various subdivisions of the lung volume

Angiographic Diagnosis of an Anomalous Right Coronary Artery Arising from the Pulmonary Artery

Abnormal origin of the coronary arteries from the pulmonary artery can occur in four different ways. Either the left or the right coronary artery, both coronary arteries, or an accessory coronary artery may arise from the pulmonary artery. The most frequent of these malformations is the abnormal origin of the left coronary artery. Many publications have dealt with the clinical, physiological, and anatomical picture of this malformation (7). The majority of patients are symptomatic in early life because of marked anoxia of the anterolateral and apical portions of the left ventricle, the result of insufficient intercoronary anastomoses. Some patients, however, may become symptomatic later in life, and in these abundant anastomoses are found between both coronary arteries. From catheterization and angiographic investigations, there is conclusive evidence that the blood flow is directed from the right coronary artery through intercoronary anastomoses into the distal branches of the left coronary artery and fr...

Blood volume and exercise

Summary 1. The increase of serum protein concentration has been determined following both moderate and vigorous exercise in experiments on eighty-five healthy boys. The blood pressure changes have also been observed. 2. In nineteen of these subjects, the increase of the concentration of the blue dye, T-1824, following exercise has also been determined. 3. In twelve of these subjects there was evidence of circulatory collapse.

Postoperative conduction disturbances in atrial septal defect

Abstract The electrocardiograms of 60 patients with atrial septal defect, aged 23 months to 37 years, were obtained after open heart surgery and analyzed. The over-all incidence of conduction abnormalities was 60 per cent; excluding first degree A-V block, it was 52 per cent. There was no significant difference in incidence between cases of secundum and primum atrial septal defect, or between those with patch repair and suture repair. Arrhythmia after total body perfusion lasting over one hour was not significantly higher than that following shorter perfusion times. The incidence of the various conduction disturbances was: A-V block, 28 per cent; right bundle branch block, 30 per cent; A-V junctional rhythm, 20 per cent; supraventricular tachycardia, 5 per cent; and atrial flutter, 2 per cent. As a rule, the arrhythmias were benign. Excluding right bundle branch block, they also tended to be transient. However, postoperative complete A-V block has persisted in 1 child for over a year. The P-R interval in the immediate postoperative period increased, decreased, or remained essentially unchanged; that observed several weeks later did not differ significantly from the preoperative level. Surgically induced right bundle branch block resulted in a distinct increase of the RS ratio in V 1 . This regressed after disappearance of block. The possible mechanisms for the postoperative A-V block and right bundle branch block are discussed.

Complete atrioventricular block associated with atrial septal defect of the fossa ovalis (secundum) type: A histopathologic study of the conduction systems☆

Abstract Two cases of atrioventricular block associated with atrial septal defect of the fossa ovalis (secundum) type are presented with comprehensive studies of the conduction system. In the first case the block was truly congenital, while in the second case it was acquired after birth. In the first case there was no connection between the defective musculature of the atrial septum with a remnant of the A-V node. In the second case there was necrosis of the A-V bundle and bifurcation. It is hypothecated that injury of the musculature of the approaches to the A-V node and of the bundle are related to the malformation of the atrial septum and consequent hemodynamic weakening of the septum and central fibrous body.