Ongley, Patrick A.

Thirty-three cases of corrected transposition of the great vessels are analyzed: 31 of corrected transposition in situs solitus, and two of corrected transposition in situs inversus. In 18 of these 33 cases, of which 64% were males, diagnosis was confirmed by necropsy or operation. There was no history of congenital heart disease in the families of any of these patients. The person whose sole anomaly is corrected transposition has no hemodynamic basis for symptoms. Symptoms are the result of associated lesions, the most common of which are anomalies of the left atrioventricular valve usually causing incompetence, ventricular septal defects, pulmonary valvular stenosis, and advanced disturbances of atrioventricular conduction. Physical findings in corrected transposition depend upon these associated defects. Noncardiac associated anomalies are rare. Anteroposterior thoracic roentgenograms may suggest the diagnosis, particularly when a narrow waist is present at the base of the heart, accompanied by the absence of a pulmonary-artery "knob" and the presence of an enlarged left atrium. Electrocardiographic features that should suggest corrected transposition are atrioventricular block (particularly 2:1 or complete heart block), abnormal P waves, absent or low R voltage in aVR, an initial Q wave in leads 3, aVR, aVF and V1, absence of a Q wave in lead V6, upright T waves across the precordium in children, and a clockwise spatial loop in the frontal plane. Cardiac catheterization may be diagnostic in this malformation when careful documentation is made of the location of the atrioventricular valves and their relation to the semilunar valves, together with the position of the great vessels in the anteroposterior and lateral views. Alteration of hemodynamics is secondary to associated malformations. Inability to enter the pulmonary artery during catheterization should arouse suspicion, and in these cases, particularly, angiocardiography can be diagnostic. The decision as to whether the most frequently associated malformations exist as isolated entities, or whether they are present in combination with corrected transposition, appears to be the main differential problem–together with the differentiation of corrected transposition with associated cyanosis from complete (that is, uncorrected) transposition. Surgical treatment of corrected transposition has been difficult because of complete atrioventricular block before or after operation, residual incompetence when deformed left atrioventricular valves were present, and the mirror-image arrangement for the coronary arteries. The most common cause of death was cardiac failure, often with a terminal bout of pulmonary edema. The average age at death in this series was about 14 years, with a median age at death of about 4 years. A review of the literature again emphasizes the association of corrected transposition with some degree of atrioventricular block evidenced on the electrocardiogram. The most frequently reported associated cardiac lesions were ventricular septal defect, pulmonary stenosis or atresia, patent ductus arteriosus, and dextrocardia. The incidence of anomalies of the left atrioventricular valve in these reported cases has probably been underestimated.

Obstructive pulmonary vascular disease (PVD) was evaluated in lung sections taken at autopsy in 53 patients with complete transposition of the great arteries. Twentythree had intact ventricular septa and 30 had ventricular septal defects. Children of similar age and associated defects had widely differing degrees of PVD and presented a spectrum of disease. In a small number of patients, the presence of pulmonic stenosis (congenital or acquired by pulmonary artery banding in infancy), a small ventricular septal defect, or a large atrial septal defect was not protective against the development of severe PVD. The findings of this study demonstrate the need for thorough hemodynamic evaluation of patients with complete transposition of the great arteries prior to repair by present technics. In addition, operation should probably be performed as soon as technically feasible.

Complete surgical correction of transposition of the great arteries associated with subvalvular pulmonary stenosis carries a high mortality rate. A new surgical technique that achieves redirection of the ventricular outflows and relieves pulmonary stenosis by bypassing it, was successfully used to repair complete transposition of the great arteries associated with ventricular septal defect (VSD) and valvular and subvalvular pulmonary stenosis in a 14½-year-old patient. The repair consists of (1) division of the pulmonary artery, the cardiac end of which is oversewn, (2) repair of the VSD with a patch in such a way as to connect the left ventricle with the aorta, and (3) reconstruction of the pulmonary artery with an aortic homograft, including the aortic valve, which is anastomosed between the distal end of the pulmonary artery and the right ventricle. A review of the cases in which the current techniques were used indicates that the location and nature of the obstruction in the left ventricular outflow tract defies successful repair in most instances. Localized ridges and diffuse hypoplastic outflow tracts are recognized causes of obstruction, but anomalies of the mitral valve commonly contribute to or are the primary cause of subvalvular obstruction.

At the Mayo Clinic, four patients were seen in whom a ventricular septal defect (VSD) of the atrioventricular (A-V) canal type was associated with an angle of nearly 90° between the intact atrial septum and the ventricular septum. The right atrium overrode the ventricular septum and communicated with both ventricles. A complex, straddling right A-V valve had some attachments in the left ventricle and resembled the common A-V valve of persistent common A-V canal. In three of the patients, a congenital mitral valve deformity also existed. Mild cyanosis probably is not a contraindication to surgical repair in such patients because right atrial blood may enter the left ventricle directly.

Data from 43 patients with common ventricle for whom satisfactory hemodynamic data are available are presented; these form 3.2% of the patients with congenital heart disease studied by means of catheterization at the Mayo Clinic. Selective biplane angiocardiography is essential for diagnosis of common ventricle. Associated cardiovascular anomalies are common, with transposition of the great vessels occurring in 84% of the patients. The right-to-left shunt present in all 43 patients results in desaturation of systemic arterial blood. The common ventricle receives all the systemic and pulmonary venous blood [see table in the PDF file] flows; yet complete mixing is uncommon in this chamber, for it occurred in only 16% of the patients who did not have severe pulmonary stenosis. Fifty-eight per cent had oxygenated blood directed preferentially to the systemic circuit ("favorable streaming"). This occurred most commonly with L-transposition and resulted in a higher oxygen saturation of systemic arterial blood. Obstruction to pulmonary flow (from pulmonary stenosis or pulmonary vascular disease) results in a larger right-to-left shunt and lower oxygen saturation of systemic arterial blood.

Introduction of a cardiac catheter into the pulmonary artery from the right heart is not possible in a substantial proportion of patients with transposition of the great vessels. It is necessary to obtain the pulmonary artery pressure and oxygen saturation value to evaluate the degree of pulmonary stenosis and the pulmonary vascular resistance. Twenty-three patients are described in whom this was accomplished by percutaneous suprasternal puncture. There was no mortality and there were no significant complications. The technique appears to be safe and reliable.

The analysis and description of the preoperative and postoperative vectorcardiograms in tetralogy of Fallot are presented. The spatial orientation of the maximum QRS vectors to the right, anteriorly, and inferiorly in group I is indicative of right ventricular hypertrophy. In group II patients, the vectorcardiogram showed evidence of increased electrical activity of the left ventricle. Vectorcardiographic patterns of complete right bundle-branch block were noted in nine patients in group III.

Eighteen cases of stenosis of the branches of the pulmonary artery, seen at the Mayo Clinic, have been reviewed and subdivided into two main types: Type I, stenosis of the main branches of the pulmonary artery, 11 cases, and type II, stenosis of multiple peripheral branches of the pulmonary arteries, seven cases. Of special interest were two cases in which thrombosis occurred as a complication and one case in which surgical relief of multiple areas of stenosis in the peripheral branches of the pulmonary arteries was accomplished. Unexplained pulmonary hypertension necessitates further investigation, which includes cardiac catheterization for measurement of intracardiac pressure and frequently selective angiocardiography. Main branch or peripheral pulmonary artery stenosis should be suspected when a continuous murmur is heard or when poststenotic dilatations of the pulmonary artery branches or areas of decreased pulmonary vasculature can be perceived in the roentgenogram. Angiocardiography is the only technic that permits detailed anatomic evaluation of the entire pulmonary vasculature, especially in the cases associated with severe infundibular or valvular pulmonic stenosis. Stenosis of the branches of the pulmonary artery must be taken into account, when surgical repair of associated cardiovascular defects is considered. These lesions also might complicate anastomotic procedures involving the pulmonary artery in cyanotic patients.

Nineteen patients with ventricular septal defect and severe aortic valvular incompetence have been operated on at the Mayo Clinic. There were two early deaths and two late deaths. The ventricular septal defect was located high and anteriorly in the septum and was often small. Aortic valvular incompetence was due, in most cases, to a deformed, prolapsing right coronary cusp. Mild to moderate degrees of infundibular pulmonary stenosis coexisted in nine patients. Repair of the ventricular septal defect was readily accomplished in most cases by direct suture, and relief of obstruction to right ventricular outflow was effected, when required, by resection of the crista supraventricularis. Repair of the aortic incompetence was attempted by a variety of means, but the incidence of persistent significant regurgitation was high, except when prosthetic cusp replacement was used. It is currently our policy to defer operation in children unless there are significant symptoms. When the patient is past the age of about 12 to 14 years, operation is advised under proper circumstances, and it consists generally of suturing of the ventricular septal defect and replacement of the right coronary cusp of the aortic valve.

Eighteen patients with the combination of ventricular septal defect and aortic insufficiency were studied. Nine also had infundibular pulmonary stenosis. Seventeen were treated by open-heart operations. The physical findings were those of a typical ventricular defect murmur and thrill together with an aortic insufficiency blow and a wide pulse pressure. A systolic murmur at the upper left sternal border with thrill is strongly suggestive of the additional lesion of infundibular pulmonary stenosis, but the presence or absence of infundibular pulmonary stenosis was indicated most accurately at cardiac catheterization and on inspection at operation. It was not of sufficient severity for signs of additional right ventricular hypertrophy to appear on the electrocardiogram. Retrograde aortography serves to demonstrate the severity of the aortic regurgitation. The problem of the surgical correction of these lesions will be the subject of a separate communication.