Dolores F. Tamer

Left isomerism and complete atrioventricular block: A report of six cases☆

Six children, aged 12 days to 13 years, with left isomerism and complete atrioventricular (A-V) block are presented. In all six patients the diagnosis of left isomerism was suggested by an interrupted inferior vena cava found during cardiac catheterization and angiocardiography; four patients had complex heart disease consisting of endocardial cushion defect, five had a common atrium, three had pulmonary stenosis, three had patient ductus arteriosus and two had dextrocardia. Further anatomic abnormalities included situs inversus of the viscera (four patients) as well as partial malrotation of the bowel. Of the six patients, four had congenital complete A-V block, whereas the remaining two had A-V conduction disturbances documented during early infancy that progressed to complete A-V block later in life. All six patients required pacemaker implantation and five of the six patients died. This report discusses the clinical presentation of complete AV block and left isomerism and reviews the literature.

Electrophysiologic cardiac function before and after surgery in children with atrioventricular canal

Thirty-two children with atrioventricular (AV) canal underwent electrophysiologic studies: 18 underwent preoperative studies at a median age of 3 years (range 6 months to 16 years); 14 underwent postoperative studies at a median age of 4 years (range 2 to 19); and 2 underwent both preoperative and postoperative matched studies. In the preoperative group the following abnormalities were observed: first-degree AV block in 5 patients (due to internodal conduction delay in 1, AV nodal conduction delay in 2 and normal intracardiac intervals in 2); internodal conduction delay but normal PR interval in 4; and disease of the sinus node in only 1. In the postoperative group the following abnormalities were observed: first-degree AV block in 9 (due to AV nodal conduction delay in 2, His-Purkinje system conduction delay in 1, upper normal intracardiac intervals in 3 and unidentified in 3); prolongation of the right ventricular apical activation time in 11 of 13 with right bundle branch block; abnormal sinus node function in 3; and abnormal AV nodal function in 4 (1 of whom had associated sinus node disease). Atrial and ventricular functions were normal in all preoperative and postoperative patients. Electrophysiologic dysfunction is rare in preoperative patients with AV canal; in postoperative patients electrophysiologic abnormalities occur in 38% and involve the sinus and AV nodes in 19 and 25%, respectively.

Anomalous origin of the left anterior descending coronary artery from the pulmonary artery

Three children were identified as having anomalous origin of the left anterior descending coronary artery (LAD) from the pulmonary artery (PA). Two had had congestive heart failure in infancy with clinical diagnosis of endocardial fibroelastosis and all had abnormal ECGs. The correct diagnosis was delayed in each case, and two patients required selective coronary angiography. Surgery was accomplished in the three children although ECG abnormalities have persisted and one child has dyskinesis of the left ventricular apex. Because this diagnosis may be difficult to make when intercoronary anastomoses are inadequate to outline the left anterior descending coronary flow into the PA, patients with clinical findings suggestive of anomalous coronary artery may require selective coronary studies to exclude this anomaly.

Atrial flutter and atrial fibrillation associated with Wolff-Parkinson-White syndrome in childhood

SummaryAtrial flutter, atrial fibrillation, or both, with the Wolff-Parkinson-White syndrome are reported in four children aged between 6 days and 12 years. The ECGs of all four patients revealed rapid ventricular rates and aberrant intraventricular conduction when atrioventricular (AV) conduction occurred via the accessory connection and slowing of the tachycardia with normalization of the QRS complex when AV conduction occurred via the AV node-His Purkinje system. Three had associated heart disease; one had a chronic congestive cardiomyopathy, one had Ebsteins anomaly of the tricuspid valve, while in the third patient an atrial septal defect was identified. When atrial flutter or fibrillation are combined with accessory AV connections, promotion by digoxin of very fast ventricular rates has been reported in adults but not in infants and older children. In two of our patients, one aged 6 days and one aged 6 months, digoxin may have produced this undesirable effect. Electrophysiologic studies as well as cardiac catheterization may be necessary for complete diagnostic evaluation in such cases. Quinidine should be considered in the management of these patients, and the use of digoxin alone may be contraindicated.

Echocardiographic assessment of right bundle branch injury after repair of tetralogy of Fallot.

SUMMARY Nineteen patients, ages 3½–18 years, with electrocardiographic evidence of right bundle branch injury after intracardiac repair of tetralogy of Fallot, underwent invasive intracardiac electrophysiologic evaluation 1–13 years (mean 4.4 years) postoperatively. Categorization of the site of right bundle branch injury as proximal or distal was made by determining the V-RVA interval. In 11 of the patients, the V-RVA interval was prolonged (> 35 msec), indicating proximal right bundle branch injury and in the other eight it was normal (< 35 msec), indicating distal bundle branch injury. Within 24 hours of the study, all patients were studied by M-mode echocardiography. Measurements were made of the tricuspid valve closure, mitral valve closure and the difference between the two, or the delta value. All but one patient with distal bundle branch injury had delta values of less than 40 msec (range 8–38 msec), while 10 of 11 patients with proximal bundle branch injury had delta values greater than 40 msec (range 41–116 msec). There was a significant positive correlation (r = 0.74, p < 0.001) between V-RVA and the delta value. We conclude that the delta value is an indicator of relative activation delay of the right ventricle, and therefore, in most cases, proximal vs distal bundle branch injury can be diagnosed noninvasively.

Cor triatriatum sinister in an adult: management guided by real time three-dimensional transesophageal echocardiography and stress echocardiography.

A 39‐year‐old female had cor triatriatum (CT) detected as an incidental finding on transthoracic echocardiography performed to evaluate chest pain. By conventional two‐ and real time three‐dimensional transesophageal echocardiography, the CT membrane had a communicating orifice connecting the accessory and main left atrial chambers that measured 1.3 × 0.8 cm. The resting mean transmembrane gradient was 2 mm Hg. The postexercise mean transmembrane gradient and pulmonary artery pressure were 6 and 40 mm Hg. Extrapolating from cutoff values for postexercise gradients and pulmonary pressures in patients with mitral stenosis, we advised deferring surgery and close clinical and echocardiographic follow up. (Echocardiography 2010;27:E132‐E136)

Induction of nonsustained atrial flutter by programmed atrial stimulation in children: Incidence, mechanisms, and clinical implications

Nonsustained atrial flutter was induced by programmed atrial extrastimulation in 6 (4%) of 137 children with preoperative congenital heart defects, who underwent electrophysiologic evaluation as part of cardiac catheterization. None of these patients had ECG or clinical evidence of arrhythmias. Atrial reentry was induced by programmed atrial extrastimulation in these six patients at coupling intervals slightly longer than the coupling interval at which flutter was induced. The flutter cycle length was similar to the atrial refractory periods. The duration ranged between 0.4 second and 60 seconds. The PA interval and the duration of the P wave were normal in all of the patients. Five of the six had normal PR intervals. It is concluded that nonsustained atrial flutter may be induced by programmed atrial extrastimulation in dysrhythmia-free children. The cycle length is determined by atrial refractoriness and, contrary to adults with clinical atrial flutter, prolonged PA and P wave duration are not predisposing factors.

Right ventricular apical activation time in children. Reference standards for clinical use.

SummaryTo differentiate proximal from peripheral right bundle-branch block, several investigators have used the right ventricular apical (RVA) activation time, but there is a lack of reference standards for infants and other children. Using intracardiac electrography, His bundle and RVA electrograms were recorded in 123 children before surgery for various types of congenital cardiac malformations. None had evidence of conduction defects on their surface ECG. The average RVA activation time was 15±7 msec (±SD) linearly increasing with age from infancy to adolescence.The values found in this large population may be useful as reference standards for right bundle-branch conduction times in other infants and children.

His-Purkinje responses and refractory periods during atrial extrastimulation in children with heart defects.

During atrial extrastimulation, split His potentials, prolonged His-to-ventricular (H,V,) intervals and block distal to the His bundle deflection were observed in both preoperative and postoperative children with heart defects. His-Purkinje responses and refractoriness were identified in 31 of 78 (40%) pediatric patients (20 of 51 preoperative and 11 of 27 postoperative) during atrial extrastimulation coupled to sinus and/or paced cycle lengths. Split His potentials were found in 14 patients (eight preoperative and six postoperative) and His bundle relative refractory periods ranged from 250–490 msec. Prolonged H2V2 intervals were found in these and in an additional 16 patients (11 preoperative and five postoperative) and the relative refractory period of the His-Purkinje system ranged from 230–500 msec. Block distal to the His deflection occurred in seven patients (five preoperative and two postoperative) and the effective refractory period ranged from 230–510 msec.Split His potentials, long H2V2 intervals and block distal to the His bundle deflection produced by atrial extrastimulation were found in preoperative as well as postoperative children. These responses probably represent functional electrophysiologic characteristics of the pediatric cardiac conduction system.

His-Purkinje conduction findings after cardiac surgery in children.

Conduction abnormalities of the His-Purkinje (HP) system are common sequelae of surgical repair of heart defects. Standard electrophysiologic recordings may fail to demonstrate abnormalities of the HP system when routine intervals are measured. When the conduction system is stressed, certain HP features that may indicate latent conduction disease within the HP system can be revealed. These features include split His potentials (SH) with spontaneous tachycardia or during rapid atrial pacing (RAP); SH with atrial extrastimuli (AES); and long HV intervals with AES associated with block distal to His during RAP. These findings may represent pathologic or functional properties of the HP system, and were identified in seven of 35 patients after surgical repair of tetralogy of Fallot (29 patients) or ventricular septal defect (six patients) who had electrophysiologic studies 1–8 years after operation. In five of the seven patients, these findings were revealed only when the conduction system was stressed. This incidence does not represent the true frequency of these features in the 35 patients because they were not evaluated under the same electrophysiologic stresses. Clinically, these patients did not differ from those manifesting these HP findings. The electrocardiographic patterns were as follows: normal QRS duration and normal axis (n = 1), right bundle branch block (RBBB) and normal axis (n = 1), RBBB and right-axis deviation (n = 4) (left anterior fascicular block (LAB] with tachycardia developed in one), RBBB and LAB (n = 1). The LAB was diagnosed on the basis of superior axis shift compared with the preoperative tracings. All had normal PR intervals.HP features may be unmasked by stressing the conduction system. The significance of these elicited conduction findings is unclear because data on the normal electrophysiologic properties of the conduction system in children are limited. Therefore, these features may be functional or pathologic.