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Related Concept Videos

Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

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Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per...
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Electrocardiogram01:29

Electrocardiogram

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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...
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Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

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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...
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Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

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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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Cardiac Action Potential01:30

Cardiac Action Potential

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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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Voltammetric Techniques: Pulse Voltammetry01:17

Voltammetric Techniques: Pulse Voltammetry

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Differential-pulse voltammetry (DPV) is a type of voltammetry that involves applying a series of voltage pulses to an electrochemical cell while measuring the resulting current. In DPV, the differential pulse or small potential pulses are superimposed on a linear potential sweep. The magnitude of these pulses is typically small, often in the millivolt range. Each voltage pulse lasts a short duration, usually in the order of a few milliseconds, and is applied at regular intervals along the...
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Updated: Mar 18, 2026

High-Throughput Analysis of Optical Mapping Data Using ElectroMap
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Microvolt T-wave Alternans: Where Are We Now?

Aapo L Aro1, Tuomas V Kenttä2, Heikki V Huikuri2

  • 1Helsinki University Hospital, Helsinki, Finland.

Arrhythmia & Electrophysiology Review
|July 13, 2016
PubMed
Summary
This summary is machine-generated.

Microvolt T-wave alternans (TWA) is a key indicator of arrhythmia risk, signaling potential ventricular arrhythmias and sudden cardiac death. While TWA shows clinical promise, further randomized trials are needed to confirm its therapeutic guidance utility.

Keywords:
Alternanselectrocardiogramlethal arrhythmiasrepolarisationrisk stratificationsudden death

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Area of Science:

  • Clinical Electrophysiology
  • Cardiovascular Research
  • Biomedical Signal Processing

Background:

  • Microvolt T-wave alternans (TWA) signifies beat-to-beat T-wave fluctuations, clinically linked to imminent ventricular arrhythmias.
  • TWA serves as a critical marker for assessing arrhythmia risk.

Purpose of the Study:

  • To review current methods for detecting TWA.
  • To discuss the clinical significance and therapeutic implications of TWA.

Main Methods:

  • Review of spectral method for TWA detection.
  • Review of time-domain modified moving average method for TWA detection.

Main Results:

  • Microvolt TWA is associated with cardiovascular mortality and sudden cardiac death in studies of over 14,000 subjects.
  • TWA is a recognized marker for lethal ventricular arrhythmias and cardiovascular death risk.

Conclusions:

  • TWA shows potential as a marker for ventricular arrhythmia susceptibility.
  • Current evidence from randomized trials is insufficient to guide therapy using TWA; ongoing trials may clarify its clinical role.