Heart rhythm : the official journal of the Heart Rhythm Society
-
Atrioventricular (AV) nodal reentrant tachycardias (AVNRT) with variable AV relationships are infrequently observed and might be misdiagnosed as atrial tachycardia. ⋯ The variations in the AV relationship were observed exclusively during atypical AVNRT in 2% of all AVNRT cases. Irregular atypical AVNRT was characterized by younger age of the patients and shorter TCL, and it more frequently required an ablation inside the CS for success. We postulate that the noted irregularity was attributable to the short TCL that gave rise to the unstable conduction in the tachycardia circuit and Wenckebach block in the lower common pathway.
-
Power spectral analysis of heart rate variability (HRV) has been used to indicate cardiac autonomic function. High-frequency power relates to respiratory sinus arrhythmia and therefore to parasympathetic cardiovagal tone; however, the relationship of low-frequency (LF) power to cardiac sympathetic innervation and function has been controversial. Alternatively, LF power might reflect baroreflexive modulation of autonomic outflows. ⋯ LF power reflects baroreflex function, not cardiac sympathetic innervation.