Related Experiment Video
Updated: May 14, 2025

Electrocardiogram Recordings in Anesthetized Mice using Lead II
Published on: June 20, 2020
Pheochromocytoma presenting with recurrent syncope, prolonged QT interval and macroscopic T-wave alternans
Raghav Bansal1, Bhavik Dhirawani2, Chetan Rathi2
1Department of Cardiology, UN Mehta Institute of Cardiology and Research Centre, Ahmedabad, Gujarat, India.
Abstract:
An 11-year-old boy presented with recurrent exertional syncope for 1 month. The baseline electrocardiogram (ECG) suggested a diagnosis of long QT syndrome with macroscopic T-wave alternans. Volatility of blood pressure and left ventricular hypertrophy triggered further investigations, revealing pheochromocytoma as the primary cause. The child underwent laparoscopic resection of the tumor with subsequent resolution of ECG changes and symptoms. The genetic testing was negative for known mutations implicated with prolonged QT interval.
Related Concept Videos
Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and...
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow...
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,...
Mechanism of Cardiac 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
Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

