Related Experiment Video

Updated: Apr 25, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
12:45

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

Published on: December 11, 2017

10.2K

Effects of atrioventricular conduction delay on the outcome of cardiac resynchronization therapy

Ying-Hsiang Lee1, Jia-Hui Wu2, Samuel J Asirvatham3

  • 1Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA; Cardiovascular Medicine, Mackay Memorial Hospital, Taipei, Taiwan.

Journal of Electrocardiology
|August 30, 2014
PubMed

Insights

Patients with a normal PR interval experienced greater improvements in heart failure functional class and left ventricular ejection fraction after cardiac resynchronization therapy (CRT) compared to those with a prolonged PR interval.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Heart Failure Management

Background:

  • First-degree atrioventricular (AV) block is a common finding.
  • Its impact on cardiac resynchronization therapy (CRT) outcomes is not well understood.
  • Understanding this relationship can optimize CRT patient selection and programming.

Purpose of the Study:

  • To investigate the association between first-degree AV block (indicated by PR interval) and CRT outcomes.
  • To compare the effectiveness of CRT in patients with normal versus prolonged PR intervals.
  • To identify predictors of CRT success in relation to AV conduction.

Main Methods:

  • Retrospective analysis of patients undergoing CRT implantation between 2002 and 2010.
  • Classification of patients into normal PR interval (n=199) and prolonged PR interval (n=204) groups.
  • Assessment of clinical and echocardiographic parameters before and 6 months after CRT.

Main Results:

  • The normal PR interval group showed significantly greater improvements in heart failure functional class (0.7 vs 0.5, P=.03).
  • Left ventricular ejection fraction also improved more in the normal PR interval group (9.4% vs 5.9%, P=.007).
  • These findings suggest a better response to CRT in patients without prolonged PR intervals.

Conclusions:

  • Normal PR interval is associated with superior outcomes following cardiac resynchronization therapy.
  • Prolonged PR interval may indicate a subset of patients who benefit less from CRT.
  • Further research should explore AV conduction characteristics in CRT responders.
Abstract

Keywords:
Atrioventricular blockCardiac resynchronizationDyssynchronyHeart failurePR intervalSurvival

More Related Videos

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System10:17

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System

Published on: April 11, 2025

2.3K
Programmed Electrical Stimulation in Mice07:29

Programmed Electrical Stimulation in Mice

Published on: May 26, 2010

20.3K

Related Concept Videos

Cardiomyopathy II: Dilated Cardiomyopathy01:30

Cardiomyopathy II: Dilated Cardiomyopathy

Dilated cardiomyopathy, or DCM, is a progressive myocardial disorder characterized by ventricular chamber dilation and contractile dysfunction.EtiologyVarious factors can cause DCM, including hypertension and heavy alcohol intake, which contribute to the weakening and enlargement of the heart muscle. Viral infections, such as Coxsackievirus B, adenoviruses, and influenza, can lead to DCM by causing inflammation and damage to heart tissue. Certain chemotherapeutic agents, including daunorubicin,...
783
Heart Failure Drugs: Inotropic Agents01:26

Heart Failure Drugs: Inotropic Agents

Positive inotropic agents are commonly used as the first line of treatment for heart failure. One such agent is digoxin, derived from the genus Digitalis, which has been known for centuries but effectively utilized since 1785. However, these cardiac glycosides can have potentially toxic effects due to their mechanism of action, which involves inhibiting Na+/K+-ATPase and increasing contractility. Digoxin is absorbed orally and distributed in various tissues, including the CNS. It has a long...
1.9K
Heart Failure VI: Adjunct Therapies01:22

Heart Failure VI: Adjunct Therapies

Additional therapies for treating patients with heart failure (HF) may include procedural interventions, supplemental oxygen, the management of sleep disorders, and nutritional therapy.Procedural InterventionsImplantable Cardioverter-Defibrillator: For patients at risk of life-threatening arrhythmias due to severe left ventricular dysfunction, an Implantable Cardioverter-Defibrillator (ICD) can detect and terminate these arrhythmias, preventing sudden cardiac death and improving survival rates.
629
Cardiomyopathy V: Interprofessional Care01:29

Cardiomyopathy V: Interprofessional Care

Managing cardiomyopathy involves addressing underlying or precipitating causes, treating heart failure with medications, and implementing dietary changes and a balanced exercise and rest regimen.Lifestyle ModificationsCardiomyopathy patients should adopt a low-sodium diet to reduce fluid retention and manage heart failure. A personalized exercise and rest plan helps maintain physical fitness without overstraining the heart. Avoiding alcohol and tobacco is essential to prevent further damage to...
745
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...
5.2K
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...
778