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Activation recovery interval 

Activation recovery interval
Activation recovery interval

Hein Heidbuchel

, Mattias Duytschaever

, and Haran Burri

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date: 03 July 2022

Introduction to the case

Dispersion of the action potential duration (APD) is considered to be a parameter for arrhythmogenicity. Detection of the action potential requires intracellular recordings, which are not feasible in the clinical setting. As a substitute for the APD, the activation recovery interval (ARI) is used (Figure 24.1), which can be derived from unipolar recordings as the interval from the depolarization to the repolarization. Although the depolarization can be determined easily in a unipolar recording, the point of repolarization is less clear.

Figure 24.1 Activation recovery interval (ARI)

Figure 24.1
Activation recovery interval (ARI)


Which interval in the electrograms marks the ARI?

  1. A The interval from the white to the green dot

  2. B The interval from the white to the red dot

  3. C The interval from the white to the blue dot

  4. D The interval from the white to the red dot for the left tracing and the interval from the white to the green dot for the right tracing.


B The interval from the white to the red dot


Activation recovery interval

In a unipolar electrogram, the activation time is the point of the steepest negative deflection in the depolarizing phase of the signal (the white dot in the signals). Simultaneous intra- and extracellular recordings have shown that the repolarization corresponds to the point of the steepest positive deflection in the repolarizing phase of the unipolar electrogram.1 It does not matter whether the configuration of the repolarization wave is only positive (right tracing), negative (left tracing), or biphasic; the time of repolarization always corresponds with the point of the steepest upstroke.2,3 In this case, the repolarization (T-wave) is flat, and the point of repolarization cannot be determined.


1. Coronel R, de Bakker JM, Wilms-Schopman FJ, et al. Monophasic action potentials and activation recovery intervals as measures of ventricular action potential duration: experimental evidence to resolve some controversies. Heart Rhythm 2006; 3: 1043–50.Find this resource:

2. Gepstein L, Hayam G, Ben Haim SA. Activation-repolarization coupling in the normal swine myocardium. Circulation 1997; 96: 4036–43.Find this resource:

3. Haws CW, Lux RL. Correlation between in vivo transmembrane action potential duration and activation-recovery intervals from electrograms. Effects of interventions that alter repolarization time. Circulation 1990; 81: 281–8.Find this resource: