Related Experiment Video

Updated: Oct 3, 2026

A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
16:40

A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation

Published on: February 28, 2012

Inappropriate discharges by fourth generation implantable cardioverter defibrillators in patients with ventricular

T Washizuka1, M Chinushi, M Tagawa

  • 1First Department of Internal Medicine, Niigata University School of Medicine, Japan. washi@med.niigata-u.ac.jp

Japanese Circulation Journal
|November 22, 2001
PubMed

Insights

Inappropriate therapies from implantable cardioverter-defibrillator (ICD) systems are common. Most issues, like tachycardia detection, can be managed by reprogramming or medication, but T-wave oversensing remains challenging.

Area of Science:

  • Cardiology
  • Biomedical Engineering
  • Electrophysiology

Background:

  • Fourth-generation implantable cardioverter-defibrillator (ICD) systems are crucial for managing cardiac arrhythmias.
  • Inappropriate therapies, or shocks delivered erroneously, are a significant concern with ICDs.
  • Understanding the causes and management of these events is vital for patient care.

Purpose of the Study:

  • To investigate the incidence, causes, and management strategies for inappropriate discharges from fourth-generation ICD systems.
  • To evaluate the effectiveness of reprogramming and pharmacological interventions in resolving inappropriate therapies.
  • To identify challenges in managing specific causes of inappropriate ICD shocks, such as T-wave oversensing.

Main Methods:

  • Prospective investigation of 45 patients with fourth-generation ICD systems.
  • Analysis of follow-up data over a mean period of 27 months.
  • Categorization of inappropriate therapies into sinus/supraventricular tachycardia and T-wave oversensing.

Main Results:

  • 40% of patients (18 out of 45) experienced inappropriate therapies.
  • Sinus and supraventricular tachycardia accounted for 15 cases, managed effectively with reprogramming and beta-blockers.
  • T-wave oversensing occurred in 3 patients, with reprogramming improving but not completely eliminating discharges.

Conclusions:

  • Inappropriate therapies are a common issue with fourth-generation ICDs, often manageable with dual-chamber systems.
  • Reprogramming detection intervals and adjusting sensitivity are key management strategies.
  • T-wave oversensing presents persistent challenges, making complete avoidance of inappropriate discharges difficult even with advanced ICD systems.

More Related Videos

Porcine Cardiac Arrest Model Using an Implantable Defibrillator08:33

Porcine Cardiac Arrest Model Using an Implantable Defibrillator

Published on: January 9, 2026

Related Concept Videos

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

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...
Disturbances in Heart Rhythm01:29

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per minute.
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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...
Cardiopulmonary Resuscitation III: AED Use01:23

Cardiopulmonary Resuscitation III: AED Use

Introduction to AEDAn Automated External Defibrillator (AED) is a portable medical device that analyzes the heart's rhythm and, if necessary, delivers an electrical shock to help the heart re-establish an effective rhythm during sudden cardiac arrest (SCA). SCA occurs when the heart suddenly and unexpectedly stops beating, leading to a loss of blood flow to the brain and other vital organs. In such emergencies, time is of the essence, and using an AED, combined with Cardiopulmonary...