Related Experiment Video
Updated: Mar 5, 2026

Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice
Published on: June 29, 2022
Complete Atrioventricular Block Presenting With Syncope Caused by Severe Hypothyroidism
Sang-Hoon Seol1, Doo-Il Kim1, Bo-Min Park1
1Division of Cardiology, Department of Internal Medicine, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Korea.
Abstract:
A 75-year-old man was admitted to our hospital with syncope. Electrocardiogram showed complete atrioventricular block and bradycardia with the minimum heart rate of 22 beats/ min. There was a possible indication for temporary cardiac pacemaker implantation. Laboratory data on admission revealed high TSH level with low free T4 level. To rule out functional atrioventricular block, we treated several days with thyroxine. A follow-up electrocardiogram showed improved heart rate without any atrioventricular block. We found that severe hypothyroidism caused a complete atrioventricular block with syncope, and thyroxine replacement completely improved these conditions.
More Related Videos
05:41Author Spotlight: Integrating Ultrasound Imaging with Biochemical Markers for Thyroid Disease Diagnosis
Published on: February 9, 2024
12:45Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Related Concept Videos
Dysrhythmias IV: Characteristics of Bradyarrhythmias
Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers
Decreased pulse rate
There are specific risk factors that can elevate the likelihood of developing bradycardia. Advanced age is a significant factor, with...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...