Septal Myectomy Outcomes in Children and Adolescents With Obstructive Hypertrophic Cardiomyopathy.

BACKGROUND: Little data exist regarding characteristics and outcomes of pediatric patients undergoing septal myectomy. We evaluated this in a large referral population. METHODS: Septal myectomy was performed in 199 consecutive patients aged ≤18 years with obstructive hypertrophic cardiomyopathy from January 1, 1976, to June 30, 2021. RESULTS: Median age was 13 years (interquartile range [IQR], 8-15 years). Left ventricular myectomy approaches included transaortic (163 of 198 [82%]), transapical (16 of 198 [8%]), and combined (19 of 198 [10%]). Right ventricular interventions included myectomy (13 of 199 [7%]) and patch reconstruction of the outflow tract (15 of 199 [8%]). Maximum left ventricular outflow tract gradients decreased after myectomy (prebypass: 50 mm Hg [IQR, 31-73 mm Hg] vs postbypass: 4 mm Hg [IQR, 0-9 mm Hg], P < .001), and this was sustained long-term (5 mm Hg [IQR, 5-10 mm Hg] at 10 years). Iatrogenic aortic and mitral valve injuries occurred in 13 of 199 (7%) and 1 of 199 (1%), respectively; however, all were successfully repaired. Operative mortality was 2 of 199 (1%). The cumulative incidence of redo myectomy was low, at 5.8% at 5 and 8.3% at 10 years. Redo myectomy patients had higher maximum left ventricular outflow tract gradients on echocardiography at predischarge and 1 year and were younger at the index operation (8 years [IQR, 2.5-10 years] vs 13 years [IQR, 9-16 years], P < .001). Overall survival at 10 years was 90%, relative to 47% in a previously reported pediatric nonoperative cohort. CONCLUSIONS: Pediatric septal myectomy provides safe, effective, and durable relief of ventricular outflow tract obstruction. Iatrogenic valve injury remains a low but nonnegligible risk. Recurrent obstruction requiring redo myectomy is infrequent and can be identified early. Long-term survival in this pediatric septal myectomy cohort appears to fare better than pediatric hypertrophic cardiomyopathy cohorts managed nonoperatively.

Pediatric Epicardial Devices: Early and Midterm Outcomes.

BACKGROUND: Lead performance is suboptimal in young patients and a main cause of device system failure. Our objective was to assess early and midterm outcomes after epicardial device implantation in a contemporary pediatric cohort. METHODS: A total of 116 consecutive pediatric patients underwent 137 epicardial device implantations from 2010 to 2019. Forty pacemakers and 97 implantable cardioverter defibrillators (ICDs) were implanted. Lead failure was defined as leads repaired, replaced, or abandoned due to fracture, dislodgement, or dysfunction. Freedom from device system failure was determined using Kaplan-Meier analysis. RESULTS: Mean age at implantation was 10 ± 5 years, 46 (34%) were younger than 8 years old, 41 (30%) had prior cardiac surgery, and 38 (28%) had prior devices. Main indications were acquired heart block (17/40 [43%]), sinus node dysfunction (14/40 [35%]), and congenital heart block (7/40 [18%]) for pacemakers, and hypertrophic cardiomyopathy (46/97 [47%]), long QT syndrome (31/97 [32%]), and ventricular arrhythmia (17/97 [18%]) for ICDs. There were no early deaths. Three-year freedom from device system failure was 80% (95% CI 73%, 88%) for all patients and 88% (95% CI 79%, 99%) for patients <8 years old. Device system failure causes included lead fracture (20/34 [59%]), lead dysfunction (5/34 [15%]), lead dislodgement (5/34 [15%]), infection (3/34 [9%]), and pericarditis (1/34 [3%]). Reintervention was required in 26/34 (76%) device system failures. CONCLUSIONS: Epicardial device implantation is safe, shows acceptable midterm outcomes in children, and is an effective option in patients younger than 8 years old. Close device surveillance continues to be essential to detect lead failure early and ensure timely reintervention.

From Safety to Benefit in Cell Delivery During Surgical Repair of Ebstein Anomaly: Initial Results.

BACKGROUND: The objective of this study is to assess the safety and early impact of intramyocardial delivery of autologous bone marrow-derived mononuclear cells (BM-MNC) at time of surgical Ebstein repair. METHODS: Patients with Ebstein anomaly (ages 6 months to 30 years) scheduled to undergo repair of the tricuspid valve were eligible to participate in this open-label, non-randomized phase I clinical trial. BM-MNC target dose was 1-3 million cells/kg. Ten patients have undergone surgical intervention and cell delivery to the right ventricle (RV) and completed 6-month follow-up. RESULTS: All patients underwent surgical tricuspid valve repair and uneventful BM-MNC delivery; there were no ventricular arrhythmias and no adverse events related to study product or delivery. Echocardiographic RV myocardial performance index improved and RV fractional area change showed an initial decline and then through study follow-up. There was no evidence of delayed myocardial enhancement or regional wall motion abnormalities at injection sites on 6-month follow-up magnetic resonance imaging. CONCLUSIONS: Intramyocardial delivery of BM-MNC after surgical repair in Ebstein anomaly can be performed safely. Echocardiography variables suggest a positive impact of cell delivery on the RV myocardium with improvements in both RV size and wall motion over time. Additional follow-up and comparison to control groups are required to better characterize the impact of cell therapy on the myopathic RV in Ebstein anomaly.

Radiofrequency ablation of the cavotricuspid isthmus for management of atrial flutter in patients with congenital heart disease after tricuspid valve surgery: A single-center experience.

BACKGROUND: Typical atrial flutter involving the cavotricuspid isthmus (CTI) is the most common reentrant arrhythmia in congenital heart disease and ablation is effective in its management. However, congenital heart disease patients often require surgical interventions on their tricuspid valve that utilize prosthetic material, making CTI ablation technically challenging. OBJECTIVE: To describe the techniques and outcomes of CTI ablation in the presence of prior tricuspid valve repair or replacement. METHODS: We included all patients who had undergone tricuspid valve repair utilizing an annuloplasty ring or tricuspid valve replacement who underwent CTI ablation for treatment of atrial arrhythmias between 2005 and 2017. Acute procedural success was defined as demonstration of bidirectional conduction block across the CTI. Long-term success was defined as lack of arrhythmia recurrence on monitoring or related symptoms. RESULTS: Sixteen patients met the inclusion criteria. Twelve (75%) patients had Ebstein's anomaly, 14 (88%) patients had a prosthetic tricuspid valve, and 2 (12%) patients had annuloplasty ring. Acute success was achieved in all cases, with no complications. Radiofrequency ablation was required on the ventricular side in 9 (56%) patients. In 1 case, ablation in the small cardiac vein was required. All patients remained free from atrial flutter during 18 months follow-up (range, 1-101 months). CONCLUSION: Our study demonstrates the safety and efficacy of catheter ablation of the CTI in the presence of a tricuspid annuloplasty ring or a prosthetic tricuspid valve. This may require ablation from the ventricular side of the valve to target atrial tissue rendered inaccessible as a result of tricuspid valve surgery.

What is the role of apical ventriculotomy in children and young adults with hypertrophic cardiomyopathy?

BACKGROUND: The transapical approach has been utilized in adult HCM patients with either midventricular obstruction or a small LV cavity; however, there are little data on its use in children. METHODS: We retrospectively reviewed all patients (age <21 years) with HCM who underwent a transapical myectomy from January 2002 to December 2016. Indication for surgery was midventricular obstruction in 19/23 (83%) and small LV cavity in 4 (17%). Preoperative symptoms included: dyspnea (96%), chest pain (65%), presyncope (61%), and syncope (35%). The mean age at the time of operation was 14 ± 4.0 years (range, 4-20). RESULTS: Overall, 23 patients (12 males) underwent transapical myectomy. A concomitant transaortic approach was performed in 16/19 (84%) with obstruction. The intraventricular gradient decreased from 71 mm Hg (IQR 44-92 mm Hg) preoperatively to 18 mm Hg (IQR 8-34 mm Hg, P < .0001) after myectomy. In patients with a small LV cavity, the mean left ventricular end diastolic dimension (LVEDD) increased from 40 ± 3 mm to 46 ± 3 mm (P = .05) after myectomy. There were no early deaths. Postoperative morbidity included complete heart block in 3 patients, 2 of which required pacemakers. Median follow up was 3.5 years (IQR 1.6-5.6). Symptoms improved in 95% of patients; the number of patients in NYHA class 3 or 4 heart failure decreased from 10/23 (43%) preoperatively to 3/23 (13%) postoperatively (P < .0001). Overall survival at 5 years postsurgery was 100%. Transplant-free survival was 91% and 87% at 1 and 5 years, respectively. CONCLUSION: In children with HCM, transapical myectomy is an effective adjunct to a transaortic approach to abolish midventricular obstruction and it effectively increases LV stroke volume in patients with small LV cavities and nonobstructive HCM. It may be beneficial for these patients with significant symptoms and who have failed medical therapy as a treatment alternative to cardiac transplantation.

Arrhythmia after cone repair for Ebstein anomaly: The Mayo Clinic experience in 143 young patients.

BACKGROUND: The increased incidence of preoperative and postoperative arrhythmia in Ebstein anomaly (EA) prompted some clinicians to perform an electrophysiology study (EPS) in all patients prior to surgery for EA. The cone repair (CR) is the current surgical option of choice for most young patients with EA but the effect of the CR on arrhythmia is not well established. OBJECTIVES: To assess the burden of arrhythmia in young patients after CR and to assess the utility of selective preoperative EPS. MATERIALS AND METHODS: A retrospective review of all patients <21 years of age with EA who had a CR at Mayo Clinic from June 2007 to December 2015 was performed. Surveys were mailed and telephone calls were made to all individuals to assess antiarrhythmic medication use and EP/device procedures performed after CR. RESULTS: There were 143 patients; median age, 10 years (0.1-20.9 years). Thirty-five (24%) patients had a preoperative EPS of which 26 (18%) had a preoperative ablation. Indications for EPS were Wolff-Parkinson-White (WPW), documented arrhythmia, or suspected arrhythmia. Posthospital discharge data were available for 140 (98%) patients. Mean follow-up was 2.9 years (0.1-9.2 years). At follow-up, 7 (5%) patients were receiving antiarrhythmic medications. After CR, only 3 (2%) patients who did not have a preoperative EPS have required an ablation. CONCLUSIONS: The risk of arrhythmia after CR for EA in young patients is very low when a preoperative EPS is limited to those with WPW, known arrhythmia, or suspected arrhythmia. In smaller patients, it may be reasonable to defer the EPS.

Minimally invasive epicardial implantable cardioverter-defibrillator placement for infants and children: An effective alternative to the transvenous approach.

BACKGROUND: Young patients have high rates of implantable cardioverter-defibrillator (ICD) lead fractures and are at risk for venous occlusion or tricuspid regurgitation with transvenous lead placement. Epicardial ICDs have the potential to circumvent complications associated with transvenous ICDs, but the literature on young patients remains limited. OBJECTIVE: The purpose of this study was to evaluate the results of a minimally invasive epicardial ICD lead placement approach in young patients. METHODS: A retrospective, institutional review board-approved electronic medical record review of all patients undergoing epicardial ICD placement at our institution from January 2011 to December 2015 was performed. RESULTS: A total of 46 patients (20 female [43%]; mean age 10.3 years, range 0.7-18.2 years; mean weight 41 ± 21 kg) were identified; 24 (52%) were ≤10 years old. A minithoracotomy was used in 28 patients (61%). All had acceptable defibrillation, right ventricular sensing, and stimulation thresholds. Median follow-up was 2.0 ± 1.3 years (range 0.02-4.5 years). Eight surgical complications occurred in 7 patients (15%), and 8 device-related complications occurred in 6 patients (13%). Fifty-eight appropriate shocks were delivered in 7 patients (15%). Four patients received inappropriate shocks in relation to lead fractures/microfractures. One patient in this cohort who had long QT syndrome type 8 died of a hypoglycemic seizure. CONCLUSION: Minimally invasive epicardial ICD placement provides an effective, alternative method for implanting an ICD system, particularly in very young patients (<6 years of age) or patients who are concerned about cosmetic appearance. This technique is an acceptable alternative to traditional transvenous ICD placement.

Wolff-Parkinson-White syndrome and adenosine response in pediatric patients.

BACKGROUND: Adenosine administration to patients with Wolff-Parkinson-White (WPW) usually increases preexcitation and therefore may be diagnostic for WPW syndrome when the electrocardiogram (ECG) is questionable. We aimed to determine the adenosine response in pediatric patients with WPW pattern on ECG and whether blocked accessory pathway (AP) conduction with adenosine correlated with nonrapid AP conduction measured by invasive electrophysiology study (EPS). METHODS: All patients with WPW ≤ 18 years of age who underwent EPS over a 5-year period were identified. The adenosine response during atrial pacing was characterized as blocked or continued AP conduction. Invasive data were obtained during atrial pacing and atrial fibrillation. Conduction through the AP to a cycle length ≤ 250 ms was considered rapid; otherwise patients were nonrapid. The sensitivity, specificity, and positive (PPV) and negative predictive value were calculated for blocked AP conduction to identify nonrapid baseline AP conduction during EPS. RESULTS: There were 59 patients included and nine (15%) had blocked AP conduction with adenosine. Five of these nine had WPW syndrome and four had fasciculoventricular APs. All nine patients had nonrapid conduction on baseline EPS. Blocked AP conduction with adenosine as a marker of nonrapid baseline AP conduction had a specificity of 100%, a PPV of 100%. CONCLUSIONS: In these pediatric patients with WPW pattern on ECG, a significant minority blocked AP conduction with adenosine and this finding had 100% specificity and PPV for nonrapid baseline antegrade AP conduction. The finding of blocked AP conduction with adenosine may aid in risk stratification.