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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 the T...

Electrocardiogram Fundamentals

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...

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

Electrophysiology of Normal Cardiac Rhythm

Electrophysiology of Normal Cardiac Rhythm

The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase of...

ECG Interpretation of Rhythms

ECG Interpretation of Rhythms

An electrocardiogram (ECG)graphically represents the heart's electrical activity on ECG paper or a monitor.
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
The horizontal axis measures time and rate, and the vertical axis measures amplitude or voltage. When...

Correlation between ECG and Cardiac Cycle

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...

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In Vivo Surface Electrocardiography for Adult Zebrafish

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Reference values of electrocardiogram repolarization variables in a healthy population.

Christian Haarmark¹, Claus Graff, Mads P Andersen

¹The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark.

Journal of Electrocardiology

|September 11, 2009

Summary

T-wave morphology analysis reveals key variables like Tpeak-Tend interval, skewness, and kurtosis are independent of age, sex, and heart rate in healthy individuals. This provides crucial reference values for T-wave interpretation.

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Area of Science:

Cardiology
Biomedical Engineering
Physiology

Background:

Lack of established reference values for T-wave morphology analysis in relation to demographic and physiological factors.
Need for characterization of T-wave morphology in a large, healthy population.

Purpose of the Study:

To characterize T-wave morphology in a large sample of healthy individuals.
To evaluate the relationship between T-wave morphology variables and age, sex, and heart rate.

Main Methods:

Analysis of 10-second digital electrocardiogram recordings from 1081 healthy subjects (17-81 years).
Calculation of T-wave morphology variables including duration, area, slopes, amplitude, skewness, and kurtosis.
Multivariate regression analysis to assess dependence on age, sex, and heart rate.

Main Results:

T-wave amplitude and area showed differences between men and women in lead V5.
Tpeak-Tend interval, skewness, and kurtosis were found to be independent of age, sex, and heart rate (r² < 0.05).
Bazett-corrected QT-interval demonstrated greater dependence on these factors (r² = 0.40).

Conclusions:

Tpeak-Tend interval, skewness, and kurtosis are clinically relevant T-wave morphology variables independent of age, sex, and heart rate.
These findings establish valuable reference values for T-wave analysis in healthy populations.
Provides a foundation for more accurate interpretation of T-wave abnormalities in clinical practice.