open access

Vol 17, No 3 (2010)
Review articles
Published online: 2010-05-28
Submitted: 2013-01-14
Get Citation

Assessing QT prolongation and electrocardiography restitution using a beat-to-beat method

Anthony A. Fossa, Meijian Zhou
Cardiol J 2010;17(3):230-243.

open access

Vol 17, No 3 (2010)
Review articles
Published online: 2010-05-28
Submitted: 2013-01-14

Abstract

Historically, the heart rate corrected QT (QTc) interval has been the standard method to assess for impaired ventricular repolarization, particularly for drug development. However, QTc does not reflect changes in autonomic state or QT-RR hysteresis which can also affect the interpretation of arrhythmogenic risk. With the advent of more accurate algorithms to automatically measure the QT interval from continuously collected digital ECG data, usage of heart rate corrected functions is no longer necessary. The dynamic beat-to-beat QT interval method compares the QT interval to individual cardiac cycles from all normal autonomic states at similar RR intervals, thus eliminating the need for correction functions. The upper 97.5% reference boundary of these beat-to-beat QT interval values is defined across the entire 24-hour RR interval range. Beats with QT intervals exceeding this limit are flagged as outlier beats for further arrhythmia vulnerability assessment. The same beat-to-beat technique can also be used to assess the QT-TQ interval relationship known as ECG restitution. This analysis potentially provides an additional means to quantify cardiac stress or arrhythmia vulnerability as the heart works more in relationship to each rest cycle.
(Cardiol J 2010; 17, 3: 230-243)

Abstract

Historically, the heart rate corrected QT (QTc) interval has been the standard method to assess for impaired ventricular repolarization, particularly for drug development. However, QTc does not reflect changes in autonomic state or QT-RR hysteresis which can also affect the interpretation of arrhythmogenic risk. With the advent of more accurate algorithms to automatically measure the QT interval from continuously collected digital ECG data, usage of heart rate corrected functions is no longer necessary. The dynamic beat-to-beat QT interval method compares the QT interval to individual cardiac cycles from all normal autonomic states at similar RR intervals, thus eliminating the need for correction functions. The upper 97.5% reference boundary of these beat-to-beat QT interval values is defined across the entire 24-hour RR interval range. Beats with QT intervals exceeding this limit are flagged as outlier beats for further arrhythmia vulnerability assessment. The same beat-to-beat technique can also be used to assess the QT-TQ interval relationship known as ECG restitution. This analysis potentially provides an additional means to quantify cardiac stress or arrhythmia vulnerability as the heart works more in relationship to each rest cycle.
(Cardiol J 2010; 17, 3: 230-243)
Get Citation

Keywords

QT prolongation; autonomic tone; restitution; electrocardiogram; beat-to-beat

About this article
Title

Assessing QT prolongation and electrocardiography restitution using a beat-to-beat method

Journal

Cardiology Journal

Issue

Vol 17, No 3 (2010)

Pages

230-243

Published online

2010-05-28

Bibliographic record

Cardiol J 2010;17(3):230-243.

Keywords

QT prolongation
autonomic tone
restitution
electrocardiogram
beat-to-beat

Authors

Anthony A. Fossa
Meijian Zhou

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: viamedica@viamedica.pl