Bundle of His electrograms in congenital corrected transposition of the great arteries. A study of two adult cases

Permanent pacemaker therapy in corrected transposition of the great arteries: analysis of site of lead placement in 40 patients

A retrospective analysis of 58 pacemaker leads in 40 patients with corrected transposition of the great arteries (CTGA) was made to compare the function of endocardial and epicardial leads. Extensive trabeculations of the normal right ventricle are generally thought to be essential for endocardial pacemaker lead stability. Because the systemic venous ventricle in CTGA lacks an extensive trabecular network, there has been concern that transvenous lead placement may result in a high rate of dislodgement. Epicardial leads have been assumed to be more reliable in these patients. Forty-seven epicardial and 11 endocardial leads were placed in 40 patients with CTGA who required permanent pacemaker therapy for symptomatic bradycardia. Of 13 episodes of epicardial lead malfunction in 158 patient-years, 3 were due to lead fracture and 10 to high thresholds. Surgery was required to correct the lead malfunction in 12 instances and thoracotomy was necessary for new lead placement in 6 patients. During 26.2 patient-years, there were 2 episodes of endocardial lead failure due to a high acute threshold and perforation. There were no instances of endocardial lead dislodgement. No association between type of failure and lead design was noted for either endocardial or epicardial leads. Actuarial analysis of survival revealed no significant differences in reliability between endocardial and epicardial leads. Endocardial lead fixation in the systemic venous ventricle in patients with CTGA is adequate to prevent lead dislodgement and preferable to epicardial lead placement because thoracotomy is avoided.

Electrophysiologic studies in patients with ventricular inversion and "corrected transposition"

We evaluated the intracardiac conduction intervals using His bundle recordings in 40 patients with ventricular inversion and 1-transposition of the great arteries. Twenty-nine subjects had 1:1 atrioventricular (AV) conduction. In 15 of those with normal PR intervals and QRS durations, the conduction intervals were not different from those of subjects with normal hearts. In the 14 patients with first-degree AV block, the block was located between the sinus node and AV node in four, between the low right atrium and bundle of His in seven, and below the common bundle of His in four. In 11 subjects with complete AV block, the stie of block was above the site of the His potential in four, below in two and within the His bundle in one. In four patients we could not record a His potential and thus could not localize the site of block. Complete block below the His recording site was associated with syncope in one patient and sudden death in another. His bundle recording is a safe technique for studying the conduction system in children with ventricular inversion and 1-transposition of the great arteries.

Lack of connection between the atria and the peripheral conduction system in a case of corrected transposition with congenital atrioventricular block

This is the first documented histologic study of the heart of a patient with corrected transposition of the great vessels and congenital atrioventricular (A-V) block with no connection between the atria and an anterior type of peripheral conduction system. Musculature in the superior (anterior) walls of both atria was absent, as was the anterior A-V node. The peripheral conduction system began with the bundle of His. In place of the absent atrial musculature, fibrosis and calcification were present. The relation of laboratory evidence of connective tissue dyscrasia in the mother to the congenital A-V block in the child is discussed.

Congenitally corrected transposition of the great vessels: localization of the site of complete atrioventricular block using his bundle electrograms

Complete atrioventricular block proximal to the bundle of His in a patient with congenitally corrected transposition of the great vessels was documented using His bundle electrograms. The spontaneous rhythnm probably originated from the bundle of His and was responsive to carotid sinus massage, atropine and isometric and treadmill exercise. These electrophysiologic observations are consistent with recent anatomic studies of congenitally corrected transposition of the great vessels.

His bundle electrogram in congenitally corrected transposition of the great vessels

His bundle electrogram was recorded in a young adult male with corrected transposition of the great vessels and single ventricle. Prolonged PA and AH intervals, wide diphasic His spike, and normal HV intervals were found. These findings are suggestive of the diffuse nature of conduction delay in this congenital lesion involving intra-atrial, AV nodal, and intra-His regions.

The conducting tissues in congenitally corrected transposition

The histopathological findings are reported in 11 cases of congenitally corrected transposition. For the purposes of this investigation, only hearts with a well-formed septum separating two ventricular sinuses were classed as corrected transposition. We did not, therefore, study any examples of single ventricle with inverted outlet chamber. Five of the cases formed the basis of a preliminary report, in which the distribution of conducting tissues in the anomaly was shown to differ from that reported in previous investigations. The six new cases confirmed this distribution. Thus, in all cases, the connecting atrioventricular node was anteriorly situated in the right atrium at the lateral junction of pulmonary and mitral valves. An anteriorly situated bundle descended into the morphologically left ventricle (right-sided) and encircled the anterolateral quadrant of the pulmonary outflow tract before descending on the anterior septum and bifurcating. The bundle branches were inverted. This distribution was observed in specimens with intact septa (three cases) and in specimens with ventricular septal defects (eight cases). In the latter cases the conducting tissues were related to the anterior quadrants of the defects. One case was of particular interest since the posterior node in the position of the normal atrioventricular node also made contact with the ventricles via a posterior bundle. In all other specimens this node was hypoplastic and did not have ventricular connections. It is considered that this finding provides a link with previous descriptions of posterior conducting tissue in congenitally corrected transposition. The findings are discussed with relation to the development of complete heart block in this anomaly.