Edward D. Overholt

Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current.

BACKGROUND Surgical or catheter ablation of accessory pathways by means of high-energy shocks serves as definitive therapy for patients with Wolff-Parkinson-White syndrome but has substantial associated morbidity and mortality. Radiofrequency current, an alternative energy source for ablation, produces smaller lesions without adverse effects remote from the site where current is delivered. We conducted this study to develop catheter techniques for delivering radiofrequency current to reduce morbidity and mortality associated with accessory-pathway ablation. METHODS Radiofrequency current (mean power, 30.9 +/- 5.3 W) was applied through a catheter electrode positioned against the mitral or tricuspid annulus or a branch of the coronary sinus; when possible, delivery was guided by catheter recordings of accessory-pathway activation. Ablation was attempted in 166 patients with 177 accessory pathways (106 pathways in the left free wall, 13 in the anteroseptal region, 43 in the posteroseptal region, and 15 in the right free wall). RESULTS Accessory-pathway conduction was eliminated in 164 of 166 patients (99 percent) by a median of three applications of radiofrequency current. During a mean follow-up (+/- SD) of 8.0 +/- 5.4 months, preexcitation or atrioventricular reentrant tachycardia returned in 15 patients (9 percent). All underwent a second, successful ablation. Electrophysiologic study 3.1 +/- 1.9 months after ablation in 75 patients verified the absence of accessory-pathway conduction in all. Complications of radiofrequency-current application occurred in three patients (1.8 percent): atrioventricular block (one patient), pericarditis (one), and cardiac tamponade (one) after radiofrequency current was applied in a small branch of the coronary sinus. CONCLUSIONS Radiofrequency current is highly effective in ablating accessory pathways, with low morbidity and no mortality.

Characterization of Reentrant Circuit in Macroreentrant Right Atrial Tachycardia After Surgical Repair of Congenital Heart Disease Isolated Channels Between Scars Allow “Focal” Ablation

Background —The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD). Methods and Results —Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan procedure in 6). Electroanatomic right atrial maps were obtained during 15 MacroATs in 13 patients, focal AT in 1 patient, and atrial pacing in 2 patients without stable AT. A large area of low bipolar voltage (≤0.5 mV) involved most of the free wall in all patients and contained 2 to 7 dense scars or lines of double potentials, forming 29 narrow channels (width ≤2.7 cm) between scars in all but 1 patient, who had a single scar and only focal AT. All 15 MacroATs were propagated through narrow channels. Ablation within the channel eliminated all 15 MacroATs with 1 to 3 (median 1) radiofrequency applications. Ablation was performed in 9 other channels identified during MacroAT (5 patients) and in 5 channels identified during atrial pacing (2 patients). Conduction block was obtained across 28 of 29 channels. After ablation, reproducible sustained right AT was not induced in any patient. During follow-up (median 13.5 months), new MacroATs, atrial fibrillation, or palpitations occurred in 3 of 16 patients. Conclusions —MacroAT after SR-CHD requires a large area of low voltage containing ≥2 scars forming narrow channels. Ablation within the channels eliminates MacroAT.

Characterization of Reentrant Circuit in Macroreentrant Right Atrial Tachycardia After Surgical Repair of Congenital Heart Disease

Background—The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD). Methods and Results—Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan procedure in 6). Electroanatomic right atrial maps were obtained during 15 MacroATs in 13 patients, focal AT in 1 patient, and atrial pacing in 2 patients without stable AT. A large area of low bipolar voltage (≤0.5 mV) involved most of the free wall in all patients and contained 2 to 7 dense scars or lines of double potentials, forming 29 narrow channels (width ≤2.7 cm) between scars in all but 1 patient, who had a single scar and only focal AT. All 15 MacroATs were propagated through narrow channels. Ablation within the channel eliminated all 15 MacroATs with 1 to 3 (median 1) radiofrequency applications. Ablation was performed in 9 other channels identified ...

Repair of Ebstein's anomaly in the symptomatic neonate: an evolution of technique with 7-year follow-up.

BACKGROUND Ebsteins anomaly in the severely symptomatic neonate is usually fatal. Until recently, successful repair has not been reported and various palliative operations have been associated with prohibitive mortality. Recently, we published our initial results with biventricular repair in 3 severely symptomatic neonates. We now update our experience with emphasis on the evolution of our surgical technique and the medium-term follow-up of these patients. METHODS Since 1994, 8 severely symptomatic neonates and young infants underwent biventricular repair by one surgeon. Six had Ebsteins anomaly and 2 had physiologically similar pathology with severe tricuspid valve dysplasia, cyanosis, and gross cardiomegaly. One Ebstein patient (2 months old) had undergone a Starnes operation elsewhere. Weight of the patients at operation ranged from 2.1 to 6.4 kg (mean 2.7 kg). Five patients had either anatomical (n = 3) or functional (n = 2) pulmonary atresia. Severe (4/4) tricuspid regurgitation was present in all except 1 (Starnes operation), and cardiothoracic ratio exceeded 0.85 in all patients. Echocardiography severity scores were >1.5 in 6 (grade 4/4) and 1.3 in 1 (grade 3/4). Repair consisted of tricuspid valve repair, reduction atrioplasty, relief of right ventricular outflow tract obstruction, partial closure of atrial septal defect, and correction of all associated cardiac defects. Technique of tricuspid valve repair evolved over time: 3 had Danielson-type repairs, 3 had DeVega-type repairs, and 2 had complex repairs. RESULTS One patient died in hospital: a 2.1 kg patient with tricuspid dysplasia, anatomical pulmonary atresia, and hypoplastic pulmonary arteries. The other 7 patients are all in functional class I and in sinus rhythm. Although 3 patients had symptomatic tachyarrhythmias before surgery, no child has experienced SVT after discharge. At recent echocardiography 4 patients had mild tricuspid regurgitation, and 2 had mild-moderate (2/4) tricuspid regurgitation. Three patients are now 7 years old, 2 are almost 2 years old, and the remaining 2 patients are 1 year old. CONCLUSIONS Surgical repair of the severely symptomatic neonate with Ebsteins anomaly is feasible and safe. The repair appears durable and with good medium-term outcome.

Neonatal repair of Ebstein's anomaly: indications, surgical technique, and medium-term follow-up.

BACKGROUND Ebsteins anomaly in the severely symptomatic neonate is usually fatal. Because the mortality for various surgical interventions has been prohibitively high, the indications for operation in these critically ill neonates are unclear. METHODS We reviewed our results with biventricular repair of three consecutive severely symptomatic neonates (2.8 to 3.2 kg) at our institution since 1994. Each had associated complex cardiac pathology, including multiple muscular ventricular septal defects (n = 1), pulmonary stenosis with functional pulmonary atresia (n = 1), and anatomic pulmonary atresia (n = 1). Preoperatively, all infants had severe tricuspid regurgitation, Great Ormond Street Ebstein echocardiogram scores greater than 1.3:1 (grade 3 or 4) and cardiothoracic ratio greater than 0.85. Two patients were severely cyanotic. Hepatic and renal insufficiency with diffuse coagulopathy was present preoperatively in two patients. Surgical repair consisted of (1) reconstruction of a competent monocuspid tricuspid valve, (2) right ventriculorrhaphy, (3) subtotal closure of atrial septal defect (ASD), (4) aggressive reduction atrioplasty, and (5) repair of all associated cardiac defects. RESULTS There were no early or late deaths. All patients are currently asymptomatic, without medications, and in sinus rhythm. At 5-year follow-up, trivial tricuspid regurgitation is present in 1 and mild regurgitation in 2 patients. On the basis of these results and review of the current literature, we propose new indications for surgical repair in the neonate with Ebsteins anomaly. CONCLUSIONS Biventricular repair of Ebsteins anomaly in the critically ill neonate is feasible and medium-term durability of the repair is excellent. Therefore, conventional management of these patients should be revised and early surgical repair encouraged.

Pulmonary autograft replacement in children. The ideal solution

Fifty-one children, aged 1.8 to 21 years (mean, 11.4) with aortic valve replacement using a pulmonary autograft are reviewed. Twenty-nine were intra-aortic implants and 22 were root replacements. There was one operative death, no late deaths, and two have required reoperation. Actuarial freedom from reoperation was 93% +/- 5.5 at 5.6 years. Freedom from progression of aortic insufficiency (AI) was 81% +/- 9 at 5.6 years in the intra-aortic implants and 86% +/- 10 in the root replacement. Enlargement of the pulmonary autograft was seen echocardiographically in both groups. This enlargement was consistent with somatic growth and not associated with progression of AI. Ten of 19 patients with aortic stenosis had an LV mass index suggestive of LV hypertrophy before operation. At 1 year, 18 of 25 had a normal LV mass index. Thirteen of 16 patients with AI had preoperative abnormal LV mass index. All but four returned to normal by 1 year. Low operative risk, excellent function, resolution of abnormal LV hemodynamics, and enlargement consistent with somatic growth suggest that the pulmonary autograft is the ideal replacement for the malfunctioning aortic valve.

Transseptal decompression of the left heart during ECMO for severe myocarditis

A 16-month-old boy suffered a cardiac arrest as a result of acute myocarditis, and venoarterial extracorporeal membrane oxygenation was instituted. Twelve hours later, acute left heart distention developed with cessation of left ventricular ejection. Under transesophageal echocardiographic guidance, a long introducer was placed into the left atrium through a transseptal puncture and connected in-line to the venous circuit. Within hours, left ventricular function improved and ejection returned. Left heart decompression was continued for 5 days, and the patient was weaned from extracorporeal membrane oxygenation after 6 days with normal cardiac and neurologic function.

Medium-term follow-up of pulmonary autograft replacement of aortic valves in children

Pulmonary autograft replacement (PAG) of the aortic valve in children has been shown to be safe and effective with a low incidence of late valve dysfunction. Relief of all types of left ventricular outflow tract obstruction using the pulmonary root has been possible. Concern about the durability of the pulmonary root in the aortic position, and the potential for growth of the pulmonary autograft used either as a root replacement or intraaortic implant, has been questioned. Sixty-five consecutive patients, aged 1.8 to 21 years (mean 12 years) operated on between September 1986 and January 1993, 35 with an intra-aortic implant (IA) and 30 with root replacement (RR), were evaluated by clinical and serial echocardiographic studies (ECHO) up to 6.5 years post-operatively. The hospital mortality rate was 3.0% (70% CL 2.1-5.1%). Two patients required reoperation for PAG insufficiency (AI), one for technical malalignment necessitating replacement at 6 months, and one with progressive leaflet prolapse due to adherence of the valve leaflet to a ventricular septal defect (VSD) patch. Freedom from significant aortic regurgitation at 6-year follow-up was 100% for RR and 91 +/- 6% for IA, and freedom from all valve-related complications including reoperation was 92 +/- 5% at 6 years. Significant enlargement of the aortic annulus which parallels somatic growth has been measured by ECHO in 17 IA implants (P < 0.001) and 17 RR patients (P < 0.01) by 1 year, and in 10 IA (P = 0.007) and 6 RR (P < 0.05) by 2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete repair of Ebstein anomaly in neonates and young infants: A 16-year follow-up

OBJECTIVE The purpose of this study was to review the long-term outcome of patients with Ebstein anomaly who underwent complete repair as neonates and young infants. METHODS Between March 1994 and May 2010, 32 patients (23 neonates and 9 young infants) underwent surgery for Ebstein anomaly. Mean weight was 3.9 ± 2.0 kg (range, 1.9-8.6 kg). The Great Ormond Street Echocardiography score was greater than 1.5 in 22 of the 23 neonates and greater than 1.0 in all infants. All associated cardiac defects were repaired including pulmonary atresia in 15 and ventricular septal defect in 4. Primary outcome measures included (1) early and late survival, (2) freedom from reoperation, (3) durability of tricuspid valve repair, and (4) functional status. RESULTS Early survival was 78.1% (25/32). There was 1 late death. Fifteen-year survival estimate was 74% ± 8%. For patients with pulmonary atresia, early and late survival was 60% ± 12% (9/15) versus 94.1% (16/17) (P < .05), respectively; for those without pulmonary atresia, early and late survival was 60% ± 12% versus 85% ± 10 (P = .06), respectively. The mean follow-up was 5.9 ± 4.5 years (0.1-16 years). A biventricular repair was achieved in 90.6% (29/32) patients. Median preoperative tricuspid regurgitation was 4/4 and at late follow-up, 1/4. Freedom from reoperation at 15 years was 74% ± 10% for patients undergoing biventricular repair. All survivors are in New York Heart Association class I or II. CONCLUSIONS Biventricular repair of Ebstein anomaly in symptomatic neonates is feasible with good early and late survival, especially in those without pulmonary atresia. Tricuspid valve repair is durable, and functional status is excellent.

Normal left ventricular function following pulmonary autograft replacement of the aortic valve in children.

To assess growth potential and hemodynamic sequelae of pulmonary autograft valves implanted into aortic outflow tracts of children, we reviewed our experience with 37 patients (2‐21 years) from August 1986 to December 1990. Twenty patients had predominantly aortic stenosis (AS), and 17 had aortic insufficiency (AI). Operative mortality was 3%. Two technical failures required reoperation. Of survivors, six (18%) have moderate AI. Pre‐ and postoperative echocardiograms were reviewed. The AS group showed increased left ventricular (LV) cavity size by > 1‐year follow‐up, and decreased LV wall and Interventricular septal thickness. In the AI group, wall and septal thickness increased by 10 days and LV cavity decreased by 10 days, 60 days, and > 1 year. Root replacements (n = 14) showed mean increases of 4.3 mm and 5.3 mm, respectively, in diameters of the aortic annulus and aortic sinuses at > 1 year. Intraaortic implants increased 3.1 mm (annulus) and 3.9 mm (sinuses) at > 1 year. The pulmonary autograft procedure is safe, and successful implantation normalizes LV dimensions and function rapidly. The autograft valve shows evidence of growth at > 1 year postoperative. The pulmonary autograft may be the ideal valve replacement in children.