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Related Concept Videos

Heart Failure II: Pathophysiology01:29

Heart Failure II: Pathophysiology

Systolic Heart Failure and Compensatory MechanismsSystolic heart failure (also termed HFrEF, Heart Failure with Reduced Ejection Fraction) is the most prevalent type of heart filure. It results in a decreased volume of blood being pumped from the ventricle. The aortic arch and carotid sinuses have baroreceptors that detect reduced blood pressure, triggering the sympathetic nervous system (SNS) to release epinephrine and norepinephrine. Initially, this response aims to boost heart rate and...
Pathophysiology of Heart Failure01:17

Pathophysiology of Heart Failure

Heart failure (HF) is a progressive syndrome involving ventricles that leads to inadequate cardiac output. It can be classified based on location and output or ejection fraction. Ejection fraction (EF) is an essential measurement in the diagnosis and surveillance of HF. Reduced EF corresponds to systolic heart failure (HFrEF). However, HF with preserved ejection fraction (HFpEF) is becoming increasingly prevalent. Also known as diastolic HF, this form of HF is related to aging. The...
Imbalances in Cardiac Output01:26

Imbalances in Cardiac Output

The heart's primary function is to pump blood throughout the body, maintaining a balance between blood sent out (cardiac output) and blood returning (venous return). If this balance is disrupted, it can result in congestive heart failure (CHF), a severe condition where the heart becomes an inefficient pump, leading to inadequate blood circulation.
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Heart Failure IV: Classification and Diagnostic Evaluation01:30

Heart Failure IV: Classification and Diagnostic Evaluation

Heart failure can be classified in various ways, with the most common classifications based on physical activity limitations, disease progression, severity, and treatment strategies.The Functional Classification of Heart Failure divides patients into four categories based on physical activity limitation due to symptom burden.Class I: Patients in this class have cardiac disease but no physical activity limitations. Ordinary activities like walking, climbing stairs, or routine tasks do not cause...
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.
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Mitral Stenosis I: Introduction01:22

Mitral Stenosis I: Introduction

Mitral Valve Stenosis (MVS) is a heart condition where the mitral valve narrows, impeding blood circulation from the left atrium to the left ventricle. The etiology and pathophysiology of this condition are multifaceted, leading to a cascade of cardiovascular complications.Causes of Mitral Valve StenosisRheumatic Heart Disease: It is the main cause of mitral valve stenosis, particularly in developing nations. This condition arises from rheumatic fever, an inflammatory illness resulting from...

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Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology·2016
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Updated: Jun 17, 2026

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

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Published on: December 11, 2017

Does defibrillation threshold increase as left ventricular ejection fraction decreases?

Jesus E Val-Mejias1, Ashish Oza

  • 1Galichia Heart Hospital, 2600 N. Woodlawn Avenue, Wichita, KS 67226, USA. val-y-mexia@hotmail.com

Europace : European Pacing, Arrhythmias, and Cardiac Electrophysiology : Journal of the Working Groups on Cardiac Pacing, Arrhythmias, and Cardiac Cellular Electrophysiology of the European Society of Cardiology
|January 6, 2010
PubMed
Summary

Defibrillation thresholds (DFTs) minimally change with decreasing left ventricular ejection fraction (LVEF) in advanced cardiac disease patients. This study found no significant increase in DFTs as LVEF declined, suggesting device efficacy is maintained across a broad LVEF spectrum.

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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
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Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs

Published on: July 12, 2022

Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Devices

Background:

  • Advanced cardiac disease is characterized by hypertrophy, fibrosis, scarring, dilatation, and conduction delays.
  • The relationship between decreasing left ventricular ejection fraction (LVEF) and defibrillation thresholds (DFTs) remains incompletely understood.
  • Previous studies have approached this question indirectly or insufficiently.

Purpose of the Study:

  • To investigate whether defibrillation thresholds (DFTs) increase as left ventricular ejection fraction (LVEF) decreases in patients with advanced cardiac disease.
  • To stratify DFTs across various LVEF ranges, expanding on prior research.
  • To provide a clearer understanding of DFT behavior in relation to cardiac function.

Main Methods:

  • Retrospective analysis of DFT data from 230 patients across three acute, multicentre, randomized studies.
  • DFTs were recorded with the SVC coil ON and optimized pulse-width waveforms (3.5 ms membrane time constant).
  • Patients were stratified into LVEF groups (LVEF > or = 46% and LVEF < or = 25%).

Main Results:

  • DFT estimates showed a minor increase from 395.2 +/- 115 V (LVEF > or = 46%) to 425.8 +/- 117.6 V (LVEF < or = 25%) as LVEF decreased.
  • These changes in DFT estimates were not statistically significant.
  • Only 3% of patients exhibited an elevated DFT (>20 J).

Conclusions:

  • Defibrillation thresholds (DFTs) change minimally, if at all, across a broad range of left ventricular ejection fraction (LVEF).
  • Results align with prior studies showing no significant DFT differences between ICD and CRT-D recipients.
  • No significant DFT differences were observed between primary and secondary prevention indications, irrespective of LVEF.