Related Experiment Video
Updated: May 30, 2026

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
Published on: April 11, 2025
Intercostal muscle twitching from right ventricular apical pacing
Siddharth A Kakodkar1, Milind G Parikh, Christopher Madias
1Rush University Medical Center, Chicago, Illinois, USA. Siddharth_Kakodkar@rush.edu
Abstract:
A patient with a dilated cardiomyopathy underwent successful implantation of a cardiac resynchronization therapy defibrillator. The device system included an active fixation lead placed at the right ventricular (RV) apex. Pacing from the RV apex unexpectedly led to left-sided intercostal muscle stimulation and twitching. This intercostal muscle twitching resolved completely with movement of the lead to the RV outflow tract.
Related Concept Videos
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Dysrhythmias III: Characteristics of Dysrhythmias
The Cardiac Cycle
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
Electrophysiology of Normal Cardiac Rhythm
Dysrhythmias II: Classification of Tachyarrhythmias

