Related Experiment Video
Updated: Jun 13, 2026

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
Published on: April 11, 2025
Right ventricular outflow tract pacing causes intraventricular dyssynchrony in patients with sick sinus syndrome: a
Wen-Hao Liu1, Bih-Fang Guo, Yung-Lung Chen
1Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Taiwan, China.
Background:
The optimal right ventricular pacing site remains controversial. The aim of this study was to assess how acute right ventricular outflow tract (RVOT) pacing affects global left ventricular function and intraventricular dyssynchrony of the left ventricle.
Methods:
Thirty-six patients with sick sinus syndrome and intact intrinsic atrioventricular conduction were enrolled. All patients underwent dual-chamber permanent pacemaker implantation, with the atrial lead placed in the right atrial appendage and the right ventricle lead positioned at the septal site of the RVOT. Chamber size, dyssynchrony index, myocardial performance index, and global left ventricular ejection fraction were determined using transthoracic two-dimensional echocardiography, tissue Doppler echocardiography, and real-time three-dimensional echocardiography.
Results:
RVOT pacing increased the myocardial performance index (0.42 +/- 0.21 with RVOT pacing vs 0.35 +/- 0.21 without RVOT pacing, P = .002) and decreased the global left ventricular ejection fraction on real-time 3-dimensional echocardiography (51.4 +/- 6.2% with RVOT pacing vs 55.9 +/- 7.1% without RVOT pacing, P = .001). Intraventricular dyssynchrony of the left ventricle induced by RVOT pacing was determined by increased septal-to-posterior wall motion delay (69.7 +/- 54.0 ms with RVOT pacing vs 22.8 +/- 22.3 ms without RVOT pacing, P < .0001), increased systolic and diastolic dyssynchrony by tissue Doppler echocardiography, and increased systolic dyssynchrony index when assessed using real-time three-dimensional echocardiography (5.56 +/- 1.74% with RVOT pacing vs 4.05 +/- 1.61% without RVOT pacing, P < .0001).
Conclusion:
Acute RVOT pacing adversely affects left ventricular function and increases intraventricular dyssynchrony in patients with sick sinus syndrome.
More Related Videos
Related Concept Videos
Dysrhythmias IV: Characteristics of Bradyarrhythmias
Dysrhythmias III: Characteristics of Dysrhythmias
ECG Interpretation of Arrhythmias I: Sinus Arrhythmias
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...
Dysrhythmias V: Evaluating Dysrhythmias
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...

