Carl N. Steeg

Method for recording electrical activity of the sinoatrial node and automatic atrial foci during cardiac catheterization in human subjects

A method for recording electrical activity of the sinoatrial (S-A) node and automatic atrial foci in human subjects is described. To record S-A nodal electrograms, an electrode catheter was inserted percutaneously into the femoral vein and advanced under fluoroscopic control to the superior vena caval-right atrial junction. The distal terminal of the catheter was placed in the area of the S-A node and the proximal terminal on the free right atrial wall or in the right atrial lumen. Polarity was reversed from the conventional electrocardiographic recording; high amplification (about 100 microV/cm) and selective filters (0.1 to 20 hertz) were used. S-A nodal electrograms recorded with this method in human subjects were similar to electrograms obtained previously from the dog and rabbit and revealed negatively directed diastolic and upstroke slopes preceding the P wave of the electrocardiogram. Sinoatrial conduction time measured from the S-A nodal electrograms in 15 cases was 34.9 +/- 2.1 ms(mean +/- standard error of the mean) for a sinus cycle length of 736.4 +/- 38.6 ms. The coronary sinus electrograms in a patient with coronary sinus rhythm were recorded by the same technique except that the distal terminal of the catheter was placed at the coronary sinus ostium. A negatively directed diastolic slope preceding the P wave was consistently recorded. This method for recording electrograms of the S-A node and ectopic automatic atrial foci should prove useful in (1) assessment of both normal and abnormal S-A nodal function, (2) direct determination of conduction time from the S-A nodal pacemaker to the atrium, and (3) localization of automatic atrial foci.

Cardiovascular malformations in the fetal alcohol syndrome.

Cardiovascular anomalies are a frequently reported feature of the fetal alcohol syndrome, but only rarely have such children been catheterized. This article fully described the cardiac anomaly in two infants with this syndrome. The malformations found in both cases include a ventricular septal defect, and the rather unusual finding of pulmonary artery dysplasia.

Reversibility of chronic obstructive lung disease in infants following repair of ventricular septal defect.

The signs of obstructive lung disease dominated the clinical course of ten infants with ventricular septal defects and large left-to-right shunts. Airway obstruction in these patients can be attributed (1) to increase in large airway resistance as the result of compression by enlarged pulmonary arteries or cardiac chambers and (2) to increase in small airway resistance as the result of accumulation of peribronchiolar fluid. The rapid regression of the signs of obstructive airway disease following open heart repair of the ventricular septal defect indicates that the lung disease observed in these infants is secondary to the ventricular septal defect, rather than a primary process. The most effective management in the refractory patient is that of open heart repair of the defect.

“Bedside” balloon septostomy in infants with transposition of the great arteries: New concepts using two-dimensional echocardiographic techniques

We performed balloon atrial septostomies in six successive infants with transposition of the great arteries, using echocardiographic guidance at the bedside in the neonatal intensive care unit. In all cases adequate septostomy was obtained and instantaneously assessable. PaO2 values increased as expected (mean before septostomy 28 mm Hg; after, 42 mm Hg). In cases of transposition clearly diagnosed echocardiographically, this intervention need not be done in the catheterization laboratory. The need for a full hemodynamic study in the neonatal period is arguable.

Postoperative assessment of porcine-valved right ventricular-pulmonary artery conduits

Insertion of extracardiac right ventricular (RV)-pulmonary artery (PA) conduits for repair of severe forms of RV-PA discontinuity has become a widely used technique. During a 10-year period, 76 patients had open heart repair with a porcine-valved RV-PA external conduit. The most common diagnoses were truncus arteriosus (15%) and pulmonary atresia with ventricular septal defect (15%). The patients were 18 days to 37 years old (median 7 years). The postoperative median follow-up period was 4 years. Four patients (8%) have been lost to follow-up. Nineteen patients (25%) died in the early postoperative period and there were 10 late deaths (13%). Calculated probability of survival was 66% at 8 years. Thirty-six patients have undergone late hemodynamic studies. A residual shunt was present in 14% of the patients; moderate to severe PA hypertension was present in 25% and significant RV-PA gradients (greater than 30 mm Hg) in 50%. The mean RV pressure for the group was 78.5 +/- 38 mm Hg. The severity of the gradients appeared to be greater in patients who had been followed longer. Ten patients have undergone reoperation because of conduit obstruction or residual shunting; 6 are alive and well. Of the surviving patients, 95% are acyanotic and without significant exercise intolerance and only 5% have cardiovascular symptoms. Thus, open heart repair using an external RV-PA conduit provides a marked improvement in the quality of life in patients who survive.

Accessory mitral valve tissue causing left ventricular outflow tract obstruction in D-transposition of the great arteries

Two patients with D-transposition of the great arteries (D-TGA) were found to have an unusual form of left ventricular outflow tract obstruction. Both had ball-like accessory mitral valve tissue that partially occluded the outflow tract. In one patient there was an intact septum, while in the other there were ventricular septal defects. The appearances have been described previously, although not in D-TGA. Recognition of accessory mitral valve tissue may allow resection of the tissue at the time of repair of the transposition complex.

Responsiveness to rapid atrial pacing of the specialized atrioventricular conduction system in children

SummaryResponsiveness to rapid atrial pacing of the specialized atrioventricular (A-V) conduction system was studied in 25 patients aged 2 months to 18 years. Atrial pacing via a catheter placed at the right atrial superior vena cava junction was initiated at rates slightly greater than the sinus rate and gradually increased to rates as high as 600 stimuli per minute. His bundle electrograms were obtained in most patients. When the atrial pacing rate (x-axis) was plotted against the corresponding ventricular rate (y-axis), the curve was M-shaped. The initial ascending limb occurred during 1:1 A-V conduction with rates as high as 270 stimuli per minute. The first descending limb resulted from Wenckebach type A-V block occurring at rates of 160 to 300 stimuli per minute. The second ascending limb corresponded to periods of 2:1 A-V block observed at rates of 200 to 536 stimuli per minute, and the final descending limb was related to higher degrees of block at both the pacing site and the A-V node. The second descending limb was seen with pacing rates of 296 to 600 stimuli per minute. The rates required to produce Wenckebach type A-V block in this group of children were higher than those reported in adults. One patient with spontaneous first-degree A-V block developed 2:1 A-V block at a pacing rate of only 150 stimuli per minute.This technique for studying the response to rapid atrial pacing of the specialized A-V conduction system characterises its functional capacity. The technique can be applied rapidly and safely in selected patients.

Total anomalous pulmonary venous drainage with ventricular septal defect

Abstract Three patients with total anomalous pulmonary venous drainage and ventricular septal defect with left-to-right shunt are presented. The ventricular septal defect was diagnosed with left ventricular angiocardiography in two patients and confirmed on postmortem examination in the third. The complex hemodynamic implications of this combination of lesions are discussed. Pulmonary artery banding is suggested as a possible method of management in early infancy. When total anomalous pulmonary venous drainage is demonstrated in infants initially suspected of having large ventricular septal defects on the basis of auscultation, left ventricular angiocardiography is mandatory. Preoperative diagnosis of a complicating ventricular septal defect is essential to optimal management.