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Related Concept Videos

Decreased pulse rate01:14

Decreased pulse rate

578
Bradycardia is a medical condition in which the heart rate is slower than normal. It occurs when the heart's natural pacemaker, the sinus node, generates slower electrical impulses than the standard rhythm. In adults, bradycardia is diagnosed when the pulse rate falls below 60 beats per minute, indicating a deviation from the normal heart rate range.
There are specific risk factors that can elevate the likelihood of developing bradycardia. Advanced age is a significant factor, with...
578
Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers01:24

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

793
Adrenergic stimulation generally impacts cardiac rate and rhythm. Specifically, stimulation of the β-adrenoceptors triggers an increase in intracellular calcium ion influx and pacemaker currents, which may cause arrhythmias. Catecholamines like adrenaline also demonstrate β2-adrenoceptor-mediated hypokalemia, impacting cardiac action potential and disrupting the normal cardiac rhythm. Class II antiarrhythmic drugs are β-adrenoceptor antagonists or β-blockers, which...
793
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

13
Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
13
Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers01:27

Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers

908
β-receptor blockers significantly impact the cardiovascular system by counteracting catecholamine-induced sympathetic responses. These medications decrease heart rate, contractility, and cardiac output, potentially leading to cardiac depression, life-threatening bradycardia, and death. Therapeutically, β-blockers function as mild antihypertensives and are utilized in treating angina pectoris and cardiac arrhythmias. However, nonselective β-blockers inhibit β2-receptors in...
908
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

905
Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
905
Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers01:12

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

1.1K
Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of...
1.1K

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Updated: Aug 5, 2025

Contractions of Human-iPSC-derived Cardiomyocyte Syncytia Measured with a Ca-sensitive Fluorescent Dye in Temperature-controlled 384-well Plates
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Drug-induced bradycardia.

Devamsh Gn1, Mallikarjun Patil2, Syed Shafiq2

  • 1St John's Medical College Hospital, Bengaluru, India devamsh.gn@gmail.com.

Clinical Medicine (London, England)
|March 23, 2023
PubMed
Summary

Mesalamine, a common ulcerative colitis treatment, can rarely cause severe sinus bradycardia (slow heart rate). Prompt withdrawal of mesalamine led to heart rate normalization in this patient, highlighting a potential adverse drug reaction.

Keywords:
bradycardiadrug side effectsmesalamineulcerative colitis

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Area of Science:

  • Gastroenterology
  • Cardiology
  • Clinical Pharmacology

Background:

  • Ulcerative colitis (UC) is a chronic inflammatory bowel disease.
  • Mesalamine (5-ASA) is a first-line treatment for mild to moderate UC.
  • Adverse effects of mesalamine are generally mild, but rare cardiovascular complications have been reported.

Observation:

  • A 45-year-old woman with acute ulcerative colitis developed symptomatic sinus bradycardia within 24 hours of starting mesalamine therapy.
  • The patient experienced giddiness and chest discomfort, with ECG confirming sinus bradycardia.
  • No acute coronary event was identified.

Findings:

  • Withdrawal of mesalamine resulted in normalization of the patient's heart rate within 24 hours.
  • The patient remained symptom-free after mesalamine discontinuation.
  • This case represents a rare instance of severe symptomatic sinus bradycardia attributed to mesalamine.

Implications:

  • Clinicians should consider mesalamine-induced bradycardia in patients with ulcerative colitis presenting with unexplained bradycardia.
  • Early recognition and withdrawal of the offending agent are crucial for managing this rare adverse drug reaction.
  • Further investigation into the mechanism of mesalamine-induced cardiotoxicity may be warranted.