Related Experiment Video
Updated: Jul 13, 2025

Analyzing Long-Term Electrocardiography Recordings to Detect Arrhythmias in Mice
Published on: May 23, 2021
An alternating QRS: How does it go even though it's pretty slow?
Emily Ong1, Eric Grubman1, Lynda E Rosenfeld1
1Section of Cardiovascular Medicine, Yale University School of Medicine, 333 Cedar St, New Haven, CT 06510, United States of America.
Abstract:
We present the case of a 42 year old patient with a history of childhood lymphoma treated with chemotherapy and radiation who underwent combined aortic and mitral valve replacements and who postoperatively developed an interesting ECG which showed complete heart block and an alternating left bundle branch and narrow complex QRS pattern at a heart rate of 69 beats per minute (bpm). We discuss potential mechanisms for this interesting pattern.
More Related Videos
Related Concept Videos
Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and...
Electrocardiogram Fundamentals
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin...
ECG Interpretation of Rhythms
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
The horizontal axis measures time and rate, and the vertical axis measures amplitude or voltage....
Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials

