Key result
VV, AH, and HV prolongations contribute more to short-term variance than shortenings, demonstrating asymmetric AV conduction.
Observational (n=10)
Conduction from the atria through the AV node and His-Purkinje system to the ventricles exhibits asymmetric variability properties in short-term tracings.
Asymmetric AV conduction variability warrants no practice change; leaves open its prognostic value and requires prospective validation.
BACKGROUND: Heart rate asymmetry is caused by an unequal contribution of heart rate decelerations and accelerations to heart rate variability. This study evaluates the asymmetric properties of the variability of the AA, HH, VV, AH and HV intervals. METHODS AND RESULTS: We recorded 50 1-min intracardiac ECG tracings from 10 patients (18-66 years old; 8 females) during a routine electrophysiological study. Standard descriptors of variance asymmetry were calculated for all intervals. Nonparametric tests were used for statistical comparisons. The prolongations of VV (P=0.0297), AH (P=0.0133) and HV (P=0.0004) intervals contributed significantly more than their shortenings to their short-term variance. The proportion of recordings with a larger contribution of prolongations than shortenings was significantly different from random for VV (0.66, P=0.0328), AH (0.68, P=0.0154) HV (0.74, P=0.0009). CONCLUSIONS: In addition to heart rate asymmetry (VV interval), the conduction from the atria, through the atrioventricular node, His-Purkinje system to ventricles shows asymmetric properties in 1-min tracings.
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Guzik et al. (2013) conducted an observational in Arrhythmias requiring electrophysiological study and ablation (n=10). Prolongations of cardiac intervals (VV, AH, HV) vs. Shortenings of cardiac intervals was evaluated on Short-term variance of the VV interval derived from prolongations (SD1p) vs shortenings (SD1s) in ms (p=0.0297). The prolongations of VV, AH, and HV intervals contributed significantly more than their shortenings to short-term variance, demonstrating asymmetry in atrioventricular conduction variability.
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