Journal of Arrhythmia (Jan 2009)
Mechanism of Ventricular Premature Contraction Showing Interpolated Bigeminy —Strong Modulation Hypothesis—
Abstract
Recent advances in invasive electrocardiology dramatically revealed the unique nature of atrial fibrillation originating from the pulmonary veins. By the same invasive technique, the origin of ventricular premature contraction (VPC) has been clarified as being located in the pulmonary outflow tract, ventricular Purkinje fibers or coronary cusps. Despite these clarifications, the essential mechanism of VPCs still remains uncertain. In addition to automaticity, the possible contribution of reentrant pathway cannot be fully ruled out. To analyze the mechanism, we previously reported on a two dimensional color display of interectopic intervals in VPC patients. This display could estimate the fundamental mechanism of VPC for a full day and clearly differentiate parasystole from fixed coupling interval VPCs. In this review, first we briefly document the historical background. In order to explain the mechanism of the much more frequently observed fixed coupling interval VPCs, we introduced a new version of color display. Using this modified version, a unique electrocardiogram associated with heart rate doubling during interpolated VPC bigeminy was depicted. The role of interpolated VPCs applied to phase analysis was stressed. From the findings, we developed a strong modulation hypothesis. Clinical significance of interpolated VPC together with heart rate doubling and harmonic feature was illustrated. Our hypothesis can be applied not only to specific form of parasystole with various coupling intervals but also to fixed coupling interval VPCs. The modified display can roughly discriminate the relative ratio of parasystole cycle length from sinus cycle length. Furthermore, simple estimation of the intrinsic automaticity cycle length together with the heart rate dependence in individual patients was possible.
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