Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Electrocardiogram01:29

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Cardiac Action Potential01:30

Cardiac Action Potential

Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

Introduction
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...
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...
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...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Hepatocyte growth factor is linked by O-glycosylated oligosaccharide on the alpha chain.

Biochemical and biophysical research communications·1992
Same author

Midline malignant B-cell lymphoma with leukemic transformation.

Cancer·1992
Same author

[The successful treatment of G-CSF in autoimmune neutropenia with liver cirrhosis complicated by esophageal varices].

[Rinsho ketsueki] The Japanese journal of clinical hematology·1992
Same author

5-S-cysteinyldopa in urine and tumors.

The Journal of dermatology·1992
Same author

Effects of hyperthermia on the effectiveness of MK-801 treatment in the gerbil hippocampus following transient forebrain ischemia.

Brain research bulletin·1992
Same author

Anomalous left brachiocephalic vein: CT findings.

Journal of computer assisted tomography·1992

Related Experiment Video

Updated: Jul 14, 2026

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
18:11

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

Published on: December 28, 2012

QRS complex changes in the V5 ECG lead during cardiac surgery.

H Tsuda1, H Tobata, S Watanabe

  • 1Department of Anesthesiology, Kurume University School of Medicine, Fukuoka, Japan.

Journal of Cardiothoracic and Vascular Anesthesia
|December 1, 1992
PubMed
Summary

Monitoring R wave amplitude in lead V5 during cardiac surgery helps assess left ventricular free wall recovery. Poorer R wave recovery in coronary artery disease patients and nonsurvivors highlights its prognostic value.

More Related Videos

In Vivo Surface Electrocardiography for Adult Zebrafish
09:13

In Vivo Surface Electrocardiography for Adult Zebrafish

Published on: August 1, 2019

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
10:17

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

Published on: April 11, 2025

Related Experiment Videos

Last Updated: Jul 14, 2026

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
18:11

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

Published on: December 28, 2012

In Vivo Surface Electrocardiography for Adult Zebrafish
09:13

In Vivo Surface Electrocardiography for Adult Zebrafish

Published on: August 1, 2019

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
10:17

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

Published on: April 11, 2025

Area of Science:

  • Cardiology
  • Cardiac Surgery
  • Electrophysiology

Background:

  • The QRS complex in lead V5 reflects left ventricular (LV) free wall activation.
  • Changes in the QRS complex during cardiac surgery can indicate myocardial stress and recovery.

Purpose of the Study:

  • To investigate the changes in R wave amplitude of the QRS complex in lead V5 during cardiac surgery.
  • To correlate these changes with patient outcomes and underlying cardiac conditions.

Main Methods:

  • Continuous monitoring of the QRS complex in lead V5 during cardiac surgery.
  • Analysis of R wave amplitude changes from pre-anesthesia through cardiopulmonary bypass (CPB) and sternal closure.
  • Comparison of R wave recovery between patients with coronary artery disease and valvular heart disease, and between survivors and nonsurvivors.

Main Results:

  • R wave amplitude significantly decreased after anesthesia induction and before CPB (P < 0.001).
  • QRS configuration changed post-cardioversion and aortic declamping, with gradual R wave recovery.
  • Patients with coronary artery disease showed poorer R wave recovery compared to valvular heart disease patients (P < 0.05).
  • Nonsurvivors exhibited significantly smaller R waves than survivors (P < 0.001).

Conclusions:

  • R wave amplitude monitoring in lead V5 is crucial for assessing LV free wall electrophysiologic recovery during cardiac surgery.
  • Changes in R wave amplitude can detect regional ischemia and predict patient outcomes.
  • The findings emphasize the importance of monitoring QRS complex changes, particularly during weaning from CPB.