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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...
Exercise Stress Test01:26

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
Dysrhythmias V: Evaluating Dysrhythmias01:30

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias, also known as arrhythmias, are disturbances in the heart's rhythm that range from benign to life-threatening. A thorough evaluation is crucial for appropriate management and involves a comprehensive medical history, physical examination, and various diagnostic tests.Medical HistorySymptoms: Collect detailed information on palpitations, dizziness, syncope, chest pain, and fatigue. Note their onset, frequency, and triggers.Previous Cardiac Issues: Document any history of heart...
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...
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...
ECG Interpretation of Rhythms01:24

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...

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Measurement of Heart Contractility in Isolated Adult Human Primary Cardiomyocytes
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How to do exercise-induced T-wave alternans testing using the spectral method.

Thomas Klingenheben1, Paweł Ptaszyński

  • 1Praxis für Kardiologie, Im Mühlenbach 2B, D-53127 Bonn, Germany. Klingenheben@bonn-kardiologie.de

Cardiology Journal
|July 25, 2008
PubMed
Summary
This summary is machine-generated.

Noninvasive microvolt T-wave alternans (mTWA) testing provides crucial insights into cardiac health. This review details clinical practice, focusing on methodologic challenges and result interpretation for accurate patient risk assessment.

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Technology

Background:

  • Microvolt T-wave alternans (mTWA) testing is a noninvasive method to assess cardiac electrical stability.
  • Accurate performance and interpretation of mTWA are critical for clinical decision-making.
  • Previous studies noted high rates of indeterminate results, necessitating standardized protocols.

Purpose of the Study:

  • To review current clinical practices for performing noninvasive mTWA testing.
  • To identify and address methodologic challenges, including patient-related and technical factors.
  • To clarify the interpretation of mTWA results, particularly indeterminate findings.

Main Methods:

  • Review of current literature and clinical guidelines on mTWA testing.
  • Analysis of factors influencing test accuracy, including noise and artifacts.
  • Discussion of the impact of beta-blocker therapy on mTWA results.
  • Evaluation of the timing of mTWA assessment in relation to cardiac disease progression.

Main Results:

  • Patient-related indeterminacy in mTWA testing is linked to increased mortality, classifying such results as 'abnormal'.
  • Technically inadequate tests are classified as indeterminate.
  • Noise and artifacts are significant challenges in mTWA assessment.
  • Beta-blocker therapy may influence mTWA results.

Conclusions:

  • Standardized protocols are essential for reliable noninvasive mTWA testing in clinical practice.
  • Understanding factors causing indeterminate results is crucial for accurate risk stratification.
  • Optimal timing for mTWA assessment is in the chronic phase of structural heart disease, not the acute setting.