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Electrocardiogram

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...

Disturbances in Heart Rhythm

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...

Pulse rhythm

Pulse rhythm

Pulse rhythm refers to the pattern of pulsations within specific intervals, offering valuable insights into the regularity or irregularity of the heart's beats as observed through the pattern of pulsation within specific intervals. A regular pulse exhibits a consistent heart rate with uniform waveforms and pulsation force, variations of which can be classified as normal, weak, or bounding.
Conversely, an irregular pulse pattern is termed dysrhythmia, stemming from disruptions in cardiac...

Mechanism of Cardiac Arrhythmias

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.

Exercise Stress Test

Exercise Stress Test

Introduction
Exercise stress testing, commonly known as a treadmill test, is a noninvasive procedure used to evaluate cardiovascular function and diagnose heart conditions.
Definition
An exercise stress test measures the heart's response to exertion using a treadmill or stationary bicycle. Chest electrodes record the heart's electrical activity through an ECG, and blood pressure is monitored regularly.
Purposes

Cardiac Action Potential

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

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Related Experiment Video

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Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

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Published on: May 5, 2022

Classification of Premature Ventricular Contractions in Athletes During Routine Preparticipation Exams.

Sofia E Gomez¹, Marco V Perez¹, Matthew T Wheeler¹

¹Department of Cardiovascular Medicine (S.E.G., M.V.P., M.T.W., D.S.K., V.F.), Stanford University School of Medicine, CA.

Circulation. Arrhythmia and Electrophysiology

|August 28, 2024

Summary

Premature ventricular contractions (PVCs) are rare in young athletes, with most cases showing benign patterns. This study provides guidance for evaluating PVCs in athletes to inform cardiac testing decisions.

Keywords:

athletes electrocardiography, ambulatory heart diseases prevalence ventricular premature complexes

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Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus

Published on: April 5, 2011

Area of Science:

Cardiology
Sports Medicine
Electrophysiology

Background:

Limited data exists on the prevalence and morphology of incidental premature ventricular contractions (PVCs) in large populations.
Athletes are a key cohort for studying incidental PVCs due to routine ECG screening during preparticipation exams.

Purpose of the Study:

To determine the prevalence and morphology of incidental PVCs in young athletes.
To provide guidance for cardiac testing and risk stratification of athletes with PVCs.

Main Methods:

Retrospective analysis of 10,728 digital ECGs from athletes aged 14-35 years.
PVCs were analyzed for morphology and categorized as benign or nonbenign using established criteria.
Simultaneous display of frontal and horizontal plane leads was used for detailed PVC analysis.

Main Results:

Only 0.24% of athletes (26 individuals) had PVCs.
The majority of PVCs (73%) exhibited a left bundle branch block pattern.
A high proportion (96%) of PVCs were classified as benign, commonly originating from the right ventricular outflow tract.

Conclusions:

Young athletes exhibit a low prevalence of PVCs, predominantly of benign morphology.
Digital ECGs with simultaneous lead display aid in evaluating PVCs and guiding further cardiac testing decisions.
Proposed algorithms can assist providers in risk stratification and decision-making for young athletes with PVCs.