What is it about?

Cardiac memory, also known as the Chatterjee phenomenon, is a poorly understood, under-recognized but important and benign cause of T-wave inversions. After a period of abnormal ventricular activation, such as ventricular pacing, intermittent left bundle branch block or preexcitation, the heart ‘remembers’ and mirrors its repolarization in the direction of the previous QRS. It usually manifests as T-wave inversions that can linger up to weeks after the provocative event. Alterations in multiple ion channels and receptors have been observed, such as transient outward potassium current (Ito), L-type calcium current (ICa), delayed rectifying potassium current (Ikr), AT1 receptors, stretch-activated receptors , Na/Ca exchanger, gap junction redistribution and apamin-sensitive small conductance calcium-activated K current (IKAS).

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Why is it important?

T-wave inversions by cardiac memory have been described after periods of ventricular pacing, intermittent left bundle branch block (LBTB), intermittent ventricular pre-excitation, ventricular tachycardia, intraventricular conduction delays and in QRS broadening associated with sodium channel block toxicity. The fact that these T-wave changes persist up to weeks after termination of the provocative factor, has broad clinical implications as T-wave inversions are seen in many pathological states such as myocardial ischemia and infarction, ventricular hypertrophy, electrolyte abnormalities (especially hypokalaemia), pulmonary embolism and increased intracranial pressure [5]. Although it is important to keep these pathological conditions in mind, knowledge of the important clinical entity being cardiac memory can prevent unnecessary admissions, expensive diagnostic tests and invasive procedures.

Perspectives

Awareness and recognition of this important electrical property of the heart can improve ECG diagnosis and help avoid unnecessary expensive or invasive tests.

Arne Ballet
Universiteit Antwerpen

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This page is a summary of: The heart remembers what the mind forgets, Acta Clinica Belgica, January 2020, Taylor & Francis, DOI: 10.1080/17843286.2020.1724449.
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