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Biomedical subjects

S N Weindling

Publications and source records attributed to S N Weindling.

8 recordsLinked to original sources
PubMed2001

Atrioventricular reciprocating tachycardia involving twin atrioventricular nodes in patients with complex congenital heart disease.

INTRODUCTION: Histologic studies of autopsy specimens described the coexistence of two distinct AV nodes (so-called "Minckeberg sling" or "twin AV nodes") in specific congenital heart defects; however, the clinical electrophysiologic (EP) characteristics of twin AV nodes have not been characterized in detail. METHODS AND RESULTS: Since April 1993, a total of seven patients with complex congenital heart disease presented with AV reciprocating tachycardia suspected to be mediated by twin AV nodes. A common anatomic finding was AV discordance ([S,L,L] or [I,D,D]) with a malaligned complete AV canal defect in 5 of 7 patients. Intracardiac EP study was performed in five cases, and ablation was attempted in three patients with successful elimination of tachycardia inducibility by interruption or modification of 1 of the 2 AV nodes. Important EP characteristics included (1) the existence of two discrete nonpreexcited QRS morphologies, each with an associated His-bundle electrogram; (2) decremental as well as adenosine-sensitive anterograde and retrograde conduction; and (3) inducible AV reciprocating tachycardia with anterograde conduction over one AV nodal pathway and retrograde conduction over the alternate AV nodal pathway. The existence of two AV nodes was further supported in the group treated with radiofrequency ablation by the development of transient accelerated junctional rhythm during energy delivery with an identical QRS morphology to that generated by anterograde conduction over the targeted AV node. CONCLUSION: Reciprocating tachycardia mediated by twin AV nodes can be a source of recurrent supraventricular tachycardia in patients with specific forms of complex congenital heart disease. Successful treatment with catheter ablation is possible.

Atrioventricular Node↗
PubMed1998

Duration of complete atrioventricular block after congenital heart disease surgery.

Children with complete heart block following surgery for congenital heart diseases were prospectively followed to assess the timing for recovery of atrioventricular conduction, and to determine if there were clinical variables that reliably predict permanent heart block. Recovery of atrioventricular conduction occurred by postoperative day 9 in 97% of patients with transient heart block.

Cardiac Surgical Procedures↗
PubMed1996

Efficacy and risks of medical therapy for supraventricular tachycardia in neonates and infants.

To assess the efficacy and safety of current pharmacologic therapy for supraventricular tachycardia (SVT) in infants, we reviewed 112 infants treated between July 1985 and March 1993. The SVT mechanism was determined by esophageal electrophysiologic study and involved an accessory pathway in 86, atrioventricular (AV) node reentry in 10, atrial muscle reentry in 11, and an ectopic atrial tachycardia in 5 patients. Of six infants not treated, none had clinical recurrences of SVT. Of the 106 patients treated, 70% remained free of tachycardia while receiving digoxin, propranolol, or both. Class I antiarrhythmic agents were necessary for 13 patients, and class III agents were required for another 13 infants. Verapamil was used in one infant with AV node reentry tachycardia. Nine infants with complex clinical presentations were believed to have failed medical management and underwent radiofrequency ablation. Five patients died, four of complications related to structural heart disease and one shortly after radiofrequency ablation was performed. No deaths appeared to be related to antiarrhythmic medications. No drug-related side effects requiring medication change occurred, and no proarrhythmia was observed. Thus medical therapy appears to be effective and safe in infants with SVT. Radiofrequency ablation should be reserved for rare infants who fail aggressive medical regimens or when the situation is complicated by ventricular dysfunction, severe symptoms, or complex congenital heart disease.

Anti-Arrhythmia Agents↗
PubMed1995

Radiofrequency ablation of intra-atrial reentrant tachycardia after surgical palliation of congenital heart disease.

BACKGROUND: Intra-atrial reentrant tachycardia (IART), also called atrial flutter, is a common and potentially lethal complication of surgical correction of congenital heart disease. Medical management of IART is often problematic, which prompts an investigation of the utility of radiofrequency (RF) ablation for management of these arrhythmias. METHODS AND RESULTS: Ten consecutive patients referred for treatment of recurrent IART after surgery for congenital heart disease were studied. Median age was 18.4 years, and median duration of arrhythmia was 6.4 years; a median of three antiarrhythmic drugs had been tried. Surgical procedures used were Fontan (6), Mustard/Senning (2), and biventricular repair (2). Intracardiac electrophysiological study demonstrated 30 distinct IART circuits, defined by activation sequence and cycle length. Mean IART cycle length was 323 +/- 114 ms. Cycle length was significantly longer in IART circuits that were successfully ablated compared with those that were not (381 versus 248 ms, P < .001). RF ablation was attempted in 22 of these circuits. Ablation sites were targeted to presumed exit points from zones of slow conduction by electrophysiological criteria. Sites chosen in this manner clustered in four distinct areas of the right atrium. Of 22 IART circuit ablations attempted, 17 (77%) resulted in acute termination of the tachycardia. In 8 of 10 patients in whom at least one IART circuit was successfully ablated, 4 are free of clinical tachycardia and 3 are improved over short-term follow-up. No complications were encountered. CONCLUSIONS: Multiple IART circuits may be present in patients after surgery for congenital heart defects. Activation sequences observed were diverse and different from those observed in atrial flutter in patients with normal anatomy. Interruption of IART circuits by RF ablation is feasible using mapping techniques aimed at identifying an exit point from a zone of slow conduction. Short-term follow-up suggests that RF ablation may be a useful adjunct in management of IART in these difficult patients.

Adolescent↗
PubMed1994

Myocardial perfusion, function and exercise tolerance after the arterial switch operation.

OBJECTIVES: This study was conducted to determine the prevalence of myocardial perfusion abnormalities at rest and exercise and to assess exercise capacity in children after the arterial switch operation. BACKGROUND: There have been sporadic reports of myocardial ischemia or sudden death in children after the arterial switch operation for transposition of the great arteries, possibly related to inadequate coronary perfusion due to kinking or stenosis of the translocated coronary arteries. METHODS: Myocardial perfusion at rest and peak exercise was assessed using the scintigraphic agent technetium-99m methoxyisobutyl isonitrile (sestamibi). Exercise capacity was determined with a modified Bruce protocol. Ambulatory electrocardiographic (ECG) Holter monitoring was performed. Ventricular function, contractility and wall motion were assessed echocardiographically. RESULTS: Twenty-three children (aged 4.2 to 7.9 years) underwent evaluation. Abnormalities were found on the rest perfusion scans in 22 children (95.6%). The left ventricular myocardium was divided into 13 segments for analysis. Of 299 rest segments, 225 (75.3%) were normal, 11 (3.7%) showed mild defects, 45 (15%) moderate defects and 18 (6%) severe defects at rest. At peak exercise, 237 segments (79.3%) were normal, 24 (8%) showed mild defects, 33 (11%) moderate defects and 5 (1.7%) severe defects. Compared with rest studies, myocardial perfusion grade at exercise was unchanged in 246 segments (82.3%), improved in 42 (14%) and worsened in 11 (3.7%). All patients had normal exercise tolerance without symptoms or ischemic ECG changes. No ventricular tachycardia was seen on Holter monitoring. All patients had a shortening fraction > or = 27%. Left ventricular contractility was normal in 12 children in whom it was assessed. Regional wall motion was normal in 17 children with adequate echocardiographic images for this analysis. CONCLUSIONS: Myocardial perfusion scan abnormalities assessed by technetium-99m sestamibi are common after an arterial switch operation. These abnormalities are of uncertain clinical significance and generally lessen with exercise. The normal exercise tolerance without symptoms or ECG changes suggests that myocardial perfusion is adequate during the physiologic stress of exercise in children up to 8 years after an arterial switch operation.

Child, Preschool↗