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Resynchronizing Right and Left Ventricles With RBBB in Congenital Heart Disease Patients
Quick Takes
- Treatment of heart failure in the congenital population with right bundle branch block remains a challenge.
- This case series demonstrates that individualized approaches to resynchronization of the right ventricle can decrease QRS duration and improve ventricular function.
Study Questions:
Can cardiac resynchronization therapy (CRT) in a congenital heart disease patient population with right bundle branch block (RBBB), including single systemic right ventricles (RVs) and subpulmonary RVs, improve ventricular function and heart failure?
Methods:
A cohort of seven consecutive patients undergoing CRT in the setting of RBBB was identified. Preprocedural imaging included (but not in all patients) echocardiogram, computed tomography, cardiac magnetic resonance imaging, and intraoperative 3D anatomical activation mapping to identify optimal lead placement. Patients with complete heart block or <3 months of follow-up were excluded.
Results:
All patients presented with moderate systolic ventricular dysfunction or worse in the context of RBBB. Two patients had single RV, three patients had tetralogy of Fallot (subpulmonary RV), and two had LVs and RBBB but small left-sided structures and VSD. The median follow-up was 9 months. Median baseline QRS duration was 180 ms (range 115-260 ms). Post-CRT, median QRS duration decrease was 34% (19-38%). All patients had improvement in systolic ventricular function.
Conclusions:
CRT in patients with systemic and subpulmonary RVs can improve heart failure. Similar techniques can improve long-term outcomes in patients with LV dysfunction and RBBB.
Perspective:
This is a retrospective study of seven complex cases with RBBB and congenital heart disease. The small sample size renders the findings difficult to generalize to other populations. We also do not see important endpoints such as exercise capacity and quality-of-life measurements. That said, QRS duration reduction has been shown to be associated with improved outcomes, and all patients had notable reductions with CRT. Of note, the two patients with LVs and RBBB had pre-CRT QRS durations of 130 and 115 ms. CRT has been shown to most benefit those with non–left bundle branch block who also have a QRS duration ≥150 ms. However, those with atypical RBBB might benefit from CRT even if the QRS duration is <150 ms, and that may indeed have been the case in the two patients with “systemic LVs.” Further areas of investigation prompted by this work, especially for nonresponders, are the roles of: 1) RV septal sensing to facilitate fused RV pacing, and 2) His bundle pacing as an alternative pacing site, anatomy permitting.
Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, Acute Heart Failure, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiac Resynchronization Therapy, Diagnostic Imaging, Echocardiography, Exercise Tolerance, Heart Failure, Heart Defects, Congenital, Magnetic Resonance Imaging, Pediatrics, Systole, Tetralogy of Fallot, Tomography, X-Ray Computed, Ventricular Function, Left
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