Preoperative and postoperative electrocardiogram in complete transposition of the great vessels

Cardiac rhythm and conduction before and after anatomic correction of transposition of the great arteries

To assess pre- and postoperative arrhythmias associated with anatomic correction of transposition of the great arteries, 34 patients had 145 standard electrocardiograms (ECGs) and 24 of these patients had 46 24-hour ECGs from 11 months before to 54 months after anatomic repair. Twenty-two patients underwent balloon atrial septostomy and 7 surgical atrial septectomy before the initial 24-hour ECG. Anatomic correction included repair of a large ventricular septal defect in 16 patients and an aortopulmonary window in 1 patient. The preoperative standard ECG showed sinus rhythm in every patient. Preoperative 24-hour tapes revealed sinus arrhythmias in 2, sinus bradycardia at a rate of less than or equal to 50 beats/min in 1, junctional rhythm in 1 and rare premature ventricular contractions (PVCs) in 1. The postoperative 24-hour ECG showed atrioventricular dissociation in 1 patient, rare premature atrial contractions in 7, rare PVCs in 8 and sinus bradycardia with junctional escape in 1. Eight patients had PVCs on the postoperative ECG that were not noted on preoperative tapes. No patient had prolonged bradycardia (less than or equal to 50 beats/min), life-threatening arrhythmias or sudden death. Except for 1 patient with atrioventricular dissociation believed to be secondary to a preventable cause, 34 patients followed for 890 patient-months after anatomic correction for transposition of the great arteries had no significant arrhythmias.

Dysrhythmias after atrial surgery in children

A retrospective study was done in 50 patients after Mustard's operation (group A) and in 204 patients after closure of a secundum atrial septal defect (group B) to analyze the postoperative dysrhythmias and to relate them to surgical factors. Forty-two percent of the patients in group A had dysrhythmias at the end of the follow-up, compared to 23% of group B patients. There was a high late mortality in group A (16%) significantly related to AF and AVJ. In group A a significant correlation was found between dysrhythmias and age at operation, use of cardioplegia, perfusion time, and the type of cannulation. In group B there was a significant relation between the location of the defect and the presence of abnormal pulmonary venous drainage. After ASD closure using hypothermia instead of cardiopulmonary bypass, the incidence of dysrhythmias was significant lower. Damage to the sinus node by cannulation and by suturing in the sinus node area is the main cause of the high incidence of dysrhythmias after atrial surgery. This high incidence should be a factor in the consideration of new types of operations.

Electrophysiologic residua and sequelae of surgery for congenital heart defects

Postoperative arrhythmias may occur in any patient who undergoes intracardiac surgery for a congenital heart defect. The correction of certain intracardiac heart defects predisposes to a large incidence of cardiac arrhythmias. Ventricular arrhythmias and conduction disturbances are seen after correction of tetralogy of Fallot, ventricular septal defect and atrioventricular canal defect. Supraventricular arrhythmias and sinus nodal dysfunction may be seen after surgery for transposition of the great arteries or atrial septal defect. The identification, evaluation and treatment of these patients are discussed.

Significance of pacemaker recovery time after the Mustard operation for transposition of the great arteries

Pacemaker recovery time corrected for cycle length was measured in 24 patients 6 months to 3 years after the Mustard operation for transposition of the great arteries. This index of sinoatrial (S-A) nodal function was obtained by subtracting the control R-R interval from the first R-R interval recorded after 3 minutes of rapid atrial pacing at the superior vena caval-right atrial junction. Recovery times were compared with those of a control group of 54 children with various forms of congenital heart disease who had not had cardiac surgery and whose electrocardiogram revealed normal sinus rhythm. The longest corrected pacemaker recovery time in the control group was 250 msec. Recovery time was normal (mean 115 msec) in 13 of the 24 patients who had undergone the Mustard procedure and prolonged (mean 472 msec) in the other 11. In 4 of these 11 a junctional escape complex was recorded before recovery of the S-A node. The configuration of the P wave and the development of dysrhythmias in the postoperative follow-up period were compared in patients with a normal and a prolonged corrected pacemaker recovery time. The incidence of dysrhythmias was much smaller in the former group. Normal sinus rhythm after the first postoperative week was noted in 10 (76 percent) of patients with a normal corrected pacemaker recovery time but in only 2 (18 percent) of those with an abnormal recovery time. One patient with an abnormal recovery time died suddenly 26 months after operation in spite of good hemodynamic repair. A prolonged pacemaker recovery time after the Mustard operation for transposition of the great arteries indicated that rhythm abnormalities were likely to develop, but a normal recovery time did not exclude abnormal sinus nodal function.

Protection of the sinus node in Mustard's operation

The occurrence of dysrhythmias after the Mustard operation for transposition of the great arteries was compared in 70 patients operated upon before and 58 patients operated upon after January 1972 when surgical modifications aimed at preserving the sino-atrial node and its arterial supply were initiated. The surgical modifications included changing the site of the superior vena cava (SVC) cannulation away from the SVC-right atrial junction, incision into the right atrial wall anterior to the sulcus terminalis, and sewing of the superior part of the baffle patch away from the sino-atrial node area. A significant decrease in the incidence of dysrhythmias occurred in the group of patients operated upon after the surgical modifications. The modifications in surgical technique have reduced but not avoided dysrhythmias.

Sick sinus syndrome after surgery for congenital heart disease

The course and prognosis of 16 infants and children with sick sinus syndrome associated with cardiac surgery is reviewed. The dysrhythmia was observed most ofter after extensive atrial reconstructive surgery in patients with transposition of the great arteries and with atrial septal defect. In 12 (75%) of the patients, sick sinus syndrome was detected in the immediate postoperative period. Tachyarrhythmias and bradyarrhythmias were presnet in 12 and isolated bradyarrhythmias in four. Temporary pacing was used in two and permanent pacing was required in five. Death in two non-paced patients was attributable to arrhythmias. Postmortem examination in one patient revealed a suture in the sinoatrial node. Careful attention to the anatomy of the sinoatrial node, its artery and the internodal tracts during surgery may prevent the development of sick sinus syndrome. In patients with dysrhythmia, a careful search should be undertaken to document the abnormal rhythm with the use of Holter monitoring. The insertion of a pacemaker is indicated in patients with tachyarrhythmias requiring cardioversion or antiarrhythmic drug therapy and those without adequate lower escape mechanisms.

Transposition of the great arteries. Results of treatment with early palliation and late intracardiac repair

A longitudinal study was made of 62 patients with dextro-transposition of the great arteries. The patients were managed with balloon atrial septostomy (BAS), palliative surgery if any operation was needed in the first year of life, and Mustard intra-atrial baffle repair after one year of age. Of the 47 patients with intact ventricular septum (IVS) treated in this manner, 41 (87 percent) were living at three months of age, 36 (77 percent) at one year, and 31 (66 percent) at two years of age. Survival rates were lower at each age for patients with associated ventricular septal defect (VSD). In relation to therapeutic interventions in the 62 patients, there were six medical deaths within one week of BAS, three deaths during palliative operations, and eight deaths associated with 31 Mustard procedures. Three patients with IVS and five with VSD developed pulmonary vascular obstructive disease, and two patients suffered strokes. In view of the relatively low mortality rate after the neonatal period and our good results with palliative surgery, we continue to defer the Mustard procedure to the second year of life. This is in contrast to the policy of some centers which now advocate elective intracardiac repair in the first year of life.

Cardiac arrhythmias following the creation of an atrial septal defect in patients with transposition of the great arteries

In 64 children with transposition of the great arteries who underwent a Blalock-Hanlon procedure, pre- and postoperative electrocardiograms were studied regarding the incidence and nature of rhythm disturbances. In another group of 19 patients with transposition of the great arteries, the atrial septal defect was created by a different surgical technique (fossa ovalis resection); this group was studied in the same way and the results were compared.

After the Blalock-Hanlon procedure seven patients developed arrhythmias including atrio-ventricular (A-V) dissociation, wandering pacemaker, bradycardia, atrial flutter, supraventricular tachycardia, supraventricular premature beats, and ectopic atrial rhythm. After fossa ovalis resection rhythm disturbances were present in three patients.

Despite their relatively high incidence it seems unlikely that arrhythmias are a major factor contributing to death irrespective of the technique used; some arrhythmias are transient and serious disturbances of long duration are rare.

Transposition of the great vessels with hypoplasia of the right ventricle

Eight cases are reported in which complete transposition of the great vessels was associated with varying degrees of hypoplasia of the right ventricle. In three, the correct diagnosis was suspected on the basis of certain electrovectorcardiographic findings and confirmed by selective angiography. Quantitative analysis of ventricular volumes and valve circumferences demonstrated that these cases represent a distinct pathological entity.

The diagnosis of complete transposition with hypoplastic right ventricle may be suggested by electrocardiographic evidence of left ventricular hypertrophy, relative absence of right ventricular QRS vectors, and leftward axis for age. The vectorcardiogram reveals a counterclockwise QRS loop in the horizontal plane, situated to the left and posteriorly. These findings occur infrequently in the young infant with complete transposition.

The presence of a hypoplastic right ventricle is confirmed by angiography, which demonstrates a small right ventricular chamber located centrally in the cardiac silhouette, not extending beyond the left border of the thoracic spine.

Disturbances in atrial rhythm and conduction following the surgical creation of an atrial septal defect by the Blalock-Hanlon technique

Disturbances in atrial conduction or rhythm, or both, were found in 16 of 27 patients undergoing the surgical creation of an atrial septal defect by the Blalock-Hanlon technique. These included P-wave aberrations of intra-atrial block and ectopic atrial rhythm, A-V rhythm, A-V dissociation, sinus bradycardia, atrial flutter, escape-capture bigeminy, and atrial premature beats. Some of these were transient and occurred within 2 weeks after surgery. It seems likely that tissue trauma engendered by the clamp and resection of the atrial septum with possible injury to the internodal conducting pathways may be the genesis of these early postoperative disturbances. Of the eight cases with transient disturbances, six occurred in this period. Later changes, such as intra-atrial block, sinus bradycardia, and atrial flutter, may be attributed to changes in atrial size secondary to the postoperative pathophysiology. Digitalis intoxication and congestive heart failure cannot be excluded as contributory factors in either the early or the late disturbances. It was not possible to correlate the incidence and nature of these disturbances with morbidity and mortality. In such severely ill, cyanotic infants, irregularities, however slight, may have altered cardiac function significantly and contributed to their deaths.