T wave alternans

T wave alternans

Illustration of T wave alternans on an ECG.

T wave alternans is a phenomenon observed in the electrocardiogram (ECG) characterized by a beat-to-beat alternation in the amplitude or shape of the T wave. This alternation can be subtle and is often detected using specialized techniques such as spectral analysis or microvolt T wave alternans testing.

Pathophysiology

T wave alternans is thought to be a marker of electrical instability in the myocardium. It is associated with the heterogeneity of repolarization across the ventricular myocardium. This heterogeneity can lead to reentrant arrhythmias and is considered a precursor to ventricular tachycardia and ventricular fibrillation.

Clinical significance

T wave alternans is used as a non-invasive marker for assessing the risk of sudden cardiac death in patients with various cardiac conditions, including ischemic heart disease, cardiomyopathy, and heart failure. It is particularly useful in identifying patients who may benefit from implantable cardioverter-defibrillator (ICD) therapy.

Detection methods

Detection of T wave alternans can be challenging due to its subtle nature. Traditional ECGs may not be sensitive enough to detect microvolt-level alternans. Advanced techniques such as spectral analysis and time-domain analysis are employed to enhance detection. These methods involve high-resolution ECG recordings and sophisticated signal processing algorithms.

Prognostic value

Studies have shown that the presence of T wave alternans is associated with an increased risk of ventricular arrhythmias and sudden cardiac death. It is considered a valuable tool in the risk stratification of patients with left ventricular dysfunction and other cardiac abnormalities.

Related pages

• Electrocardiogram
• Ventricular tachycardia
• Sudden cardiac death
• Implantable cardioverter-defibrillator