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.

SUMMARY Only two cases have been reported previously of the association of ventricular septal defect (VSD) with anomalous origin of the left coronary artery (ALCA) arising from the pulmonary artery. The purpose of this paper is to present two additional cases, to describe the pathophysiology, and to emphasize how the clinical course of this combination of defects differs from that of isolated ALCA.Patients with both of these anomalies present in infancy with manifestations only of a large left-right ventricular shunt and SINCE ANOMALOUS ORIGIN OF THE LEFT CORONARY ARTERY (ALCA) from the pulmonary artery was described by Abbot in 19081 and the natural course further characterized by Bland, White and Garland in 1933,2 numerous reports have been published describing symptoms and modes of therapy.3 Associated congenital cardiac anomalies are extremely rare. Since many cardiac centers are repairing ventricular septal defects in infants when medical management is not satisfactory, then it becomes important to properly identify associated defects. To the best of our knowledge, there are only two published cases concerning the association of ALCA with ventricular septal defect (VSD).78It is the purpose of this paper to report two additional cases of ALCA associated with VSD, to describe the hemodynamics, and to emphasize the difference in the clinical course of ALCA, both with, and without additional congenital cardiac defects. Patient MaterialCase I T.S. was brought to the emergency room at 11 weeks of age because of poor feeding, tachycardia, and tachypnea. On examination she was underdeveloped, irritable, and acyanotic. The respiratory rate was 50 per minute and the heart rate was 140 beats per minute. The first heart sound was normal but the second sound was single and of increased intensity. There was a plateau, III/VI holosystolic murmur at the left lower sternal border with radiation to the base and to the posterior chest wall bilaterally. There was a short, low-frequency mid-diastolic murmur at the apex. The liver was enlarged 3 cm below the right costal margin. The chest radiograph demonstrated cardiomegaly with increased pulmonary arterial markings. The electrocardiogram demonstrated biventricular hypertrophy ( fig. la). There were no electrocardiographic changes suggestive of ALCA. Digitalis and diuretics were administered with prompt improvement. The clinical impression was VSD. Cardiac catheterization six days later revealed a VSD. There was a significant increase in oxygen saturation in the right ventricle, with no further increase in the pulmonary artery. Other hemodynamic data are listed in table 1.During the next six months, the patient had numerous episodes of unexplained irritability, crying and tachycardia. However, the systolic murmur decreased in intensity and the diastolic murmur disappeared. Thus, despite auscultatory evidence of decrease in size of the VSD, the patient continued to have symptoms of distress and cardiomegaly by chest radiograph. There was diminution of the R wave in the anterior ...

Electrophysiological studies were carried out in 7 subjects with angiographically proven ventricular inversion in order to determine if this technique could be used in the study of arrhythmias in such subjects. Three subjects with normal PR intervals on the electrocardiogram had normal low right atrium to His (LRA-H) and His to ventricle (HV) intervals at rest. With atrial pacing, I of these 3 with normal PR interval developed Mobitz II second-degree atrioventricular block. Of 2 subjects with first-degree atrioventricular block r was found to have prolonged LRA-H and HV intervals, and the other had only LRA-H prolongation. In both subjects with complete atrioventricular block, the block was below the His bundle recording site. One of these patients with complete A V block was found to be able to conduct through his A V conducting system during the supernormal period. This study found that useful information can be obtained by recording the His bundle potential in patients with ventricular inversion. Conduction abnormalities were found from the A V node through the His-Purkinje system. This technique may be useful in making clinical decisions in patients with ventricular inversion and complex arrhythmias.

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