L.H.S. Van Mierop

Anomalous origin of a pulmonary artery from the ascending aorta: Associated anomalies and pathogenesis

The pathologic anatomic features and associated cardiovascular anomalies of 9 patients with anomalous origin of 1 pulmonary artery (PA) from the ascending aorta seen at the University of Florida and 99 previously reported cases were analyzed. Anomalous origin of the right PA was much more common than anomalous origin of the left PA. The anomalous right PA usually arose from the posterior aspect of the ascending aorta close to the aortic valve. Less commonly, it originated from the lateral ascending aorta just proximal to the innominate artery. Patent ductus arteriosus and aorticopulmonary septal defect were commonly associated with anomalous origin of the right PA; other cardiovascular anomalies were rare. In contrast, tetralogy of Fallot and aortic arch anomalies, e.g., right aortic arch and anomalous origin of the subclavian artery, were common in anomalous origin of the left PA. An association with DiGeorge syndrome, frequently noted with persistent truncus arteriosus, was not seen with anomalous origin of a PA from the ascending aorta. The observations indicate that anomalous origin of the right PA and anomalous origin of the left PA are pathogenetically unrelated to each other and both are unrelated to persistent truncus arteriosus. Moreover, anomalous origin of the right PA arising close to the innominate artery is thought to be pathogenetically distinct from the type that arises close to the aortic valve. These pathogenetic relations should be considered in epidemiologic studies of congenital heart disease.

The radiographic appearance of the tracheobronchial tree as an indicator of visceral situs

Abstract To arrive at an accurate anatomic diagnosis in patients with complex cardiovascular malformations or abnormal position of the heart, the situs of the viscera, or more specifically, that of the atria, must be known. Since the situs of the atria always corresponds to that of the tracheobronchial tree, the latter is a very reliable indicator of visceral (atrial) situs. A chest roentgenogram taken in the anteroposterior or posteroanterior projection will show the anatomy of the air-filled trachea and main bronchi, thus indicating whether there is situs solitus, situs inversus or “situs ambiguus”. The latter term is introduced to indicate that in many patients with asplenia or polysplenia syndrome, the visceral situs cannot be determined because of symmetrical development of normally asymmetrical organs.

Pulmonary atresia with and without ventricular septal defect: a different etiology and pathogenesis for the atresia in the 2 types?

In 15 of 20 hearts of neonates with pulmonary atresia and intact septum (PA-IVS) and in 4 with critical pulmonary stenosis, the pulmonary valve consisted of 3 fused cusps. One of the 11 patients with a ventricular septal defect (PA-VSD) had a well-developed pulmonary root; in 8 the pulmonary trunk arose from a dimple. Two had a bicuspid valve. In 10 of the 20 patients with PA-IVS and in those with critical stenosis, the diameter of the pulmonary trunk was normal or larger than normal. The authors believe that this is related to flow through an initially patent pulmonary valve and, perhaps more importantly, to poststenotic dilatation. In all hearts with PA-VSD, the pulmonary trunk was very small. In the patients with PA-IVS and a normal-sized pulmonary trunk and in 3 with critical pulmonary stenosis, the morphology of the ductus arteriosus was normal, suggesting that even in the former the valve was patent before birth, allowing forward flow. In all patients with small pulmonary trunk, the ductus was long, tortuous, and originated from the aortic arch in a proximal position, suggesting that reversal of flow had occurred early in development. The authors postulate that in patients with ventricular septal defect (VSD), the pulmonary ostium becomes atretic early in development, at or shortly after partitioning of the truncoconal part of the heart has taken place but before closure of the ventricular septum. In patients with intact ventricular septum, on the other hand, atresia very likely occurs sometime after cardiac septation has been completed. In these cases the pulmonary atresia may be due to a prenatal inflammatory process, rather than representing a true congenital malformation.

Pathogenetic mechanisms in congenital cardiovascular malformations

C ONGENITAL ANOMALIES have aroused man’s curiosity, superstition, fear, and awe for many centuries. Explanations concerning their etiology and pathogenesis based upon supernatural forces, fatalism, mysticism, philosophy, and scholarly, if not always well founded, scientific reasoning have been offered for almost as long a time. Cardiac anomalies have enjoyed more than their share of interest, either because they are common and usually have profound influence on the life of the individual, or because the heart is an organ which has always had a certain special significance for man, possibly because it seems to have such an obvious, active life of its own within the body and reacts so rapidly and obviously to changes in man’s emotional status. To date, no one has had the opportunity to actually observe the pathogenesis of cardiovascular malformations by systematic study of embryologic material. While it has been possible for many years to induce cardiac (and other) anomalies in experimental animals, the effect of various teratogens appears to be rather nonspecific, and, therefore, the malformations produced by any one agent are not consistently all of the same type. Stockard’ concluded from his classical work with Fundulus that different disturbances applied at the same phase of development would tend to produce the same defects, whereas the same disturbing factor applied at different phases of development produces different defects. While this may be somewhat of an oversimplification, there seems to be little doubt that in many, if not most cases, the nature of the injurious agent is not as important a determining factor as the precise time in early development at which it is allowed to exert its influence. Such exact timing in administering an experimental insult is virtually impossible, certainly so in mammals. Thus, it has not been possible as yet to induce transposition complexes, tetralogy of Fallot, or any other specific anomaly reproducibly, and in a high enough percentage of offspring to render embryologic studies practicable and reliable. For this reason, experimental work aimed at producing cardiac anomalies has little or no value for the study of the pathogenesis of such anomalies. Recently, Gessne? has been able to create cardiac anomalies of a fairly uniform type (double outlet right ventricle and double inlet left ventricle) in chick embryos by mechanical means. Undoubtedly, the reason such uniform results

The morphologic development of the sinoatrial node in the mouse

Abstract A plastic embedding technique was employed on mouse embryos after fixation with a gluteraldehyde-paraformaldehyde mixture and preparation of large, 1 to 2 μ sections cut on a rotary microtome with steel knives. It was then possible to trace the sinoatrial node back to mouse embryos of 4 sol1 2 mm crown-rump length ( 10 1 2 days gestational age, corresponding developmentally to 6 mm human embryos). In the mouse, the sinoatrial node lies anteromedially just above the cavoatrial junction. The nodal artery, which is located more or less centrally, is a branch of the internal mammary artery, not of the coronary arterial system. Even in the youngest embryos examined thus far, the node is strictly unilateral in structure.

Hemolytic anemia secondary to erosion of a Silastic band into the lumen of the pulmonary trunk.

Abstract Hemolysis resulting from mechanical damage to red blood cells has been reported after cardiac valve replacement and after closure of septal defects with prosthetic materials. We have observed a child in whom a Silastic ® band placed around the pulmonary trunk eroded through the vessel wall and was stretched across the lumen causing pronounced hemolytic anemia.

The changing strategies in operation for transposition of the great vessels

Between July 3, 1985, and February 24, 1994, a total of 55 infants underwent arterial switch procedures for the repair of transposition of the great vessels. Thirty-five infants had an intact ventricular septum and 20 had ventricular septal defects. To date, there have been three late deaths, one in the group with an intact ventricular septum and two in the group with a ventricular septal defect. Early postoperative complications included atrial dysrhythmias, prolonged ventilation, inability to close the sternum, and tension on the coronary arteries. Follow-up echocardiographic data for 44 patients indicate that pulmonary artery gradients are a worrisome postoperative problem, especially in infants who have ventricular septal defects.

Correction of Ventricular Septal Defect in Childhood

Abstract One hundred and two consecutive patients underwent operative repair of ventricular septal defect with 9 operative deaths. Preoperative cardiac catheterization was performed in 100 patients. Severe pulmonary hypertension was present preoperatively in 8 of the 9 patients who died. Two patients had permanent heart block. Postoperative cardiac catheterization was performed in three-quarters of the surviving patients. Two patients had significant residual ventricular septal defect. The 92 surviving patients have been followed up to eleven years postoperatively and are asymptomatic.