Abnormal Atrioventricular Node Conduction and Atrioventricular Nodal Reentrant Tachycardia in Patients Older Versus Younger Than 65 Years of Age

Study Objective: We examined the possible role of atrioventricular node (AVN) conduction abnormalities as a cause of AVN reentrant tachycardia (RT) in patients >65 years of age.
Study Population: Slow pathway radiofrequency catheter ablation (RFCA) was performed in 104 patients. Patients in group 1 (n = 14) were >65 years of age and had AV conduction abnormalities associated with structural heart disease. Patients in group 2 (n = 90) were <65 years of age and had lone AVNRT.
Results: Patients in group 1 versus group 2 (66% vs. 46% men) had a first episode of tachycardia at an older age than in group 2 (68 ± 16.8 vs 32.5 ± 18.8 years, P = 0.007). The history of arrhythmia was shorter in group 1 (5.4 ± 3.8 vs 17.5 ± 14, P = 0.05) and was associated with a higher proportion of patients with underlying heart disease than in group 2 (79% vs 3%, P < 0.001). The electrophysiological measurements were significantly shorter in group 2: atrial-His interval (74 ± 17 vs 144 ± 44 ms, P = 0.005), His-ventricular (HV) interval (41 ± 5 vs 57 ± 7 ms, P = 0.001), Wenckebach cycle length (329 ± 38 vs 436 ± 90 ms, P = 0.001), slow pathway effective refractory period (268 ± 7 vs 344 ± 94 ms, P = 0.005), and tachycardia cycle length (332 ± 53 vs 426 ± 56 ms, P = 0.001). The ventriculoatrial block cycle length was similar in both groups. The immediate procedural success rate was 100% in both groups, and no complication was observed in either group. One patient in group 2 had recurrence of AVNRT. One patient with a 98-ms HV interval underwent permanent VVI pacemaker implantation before RFCA procedure.
Conclusion: In patients undergoing RFCA for AVNRT at >65 years of age had a shorter history of tachycardia-related symptoms than patients with lone AVNRT. The longer AVN conduction intervals and refractory period might explain the late development of AVNRT in group 1.     

Relationships between blood pressure variability and left ventricular parameters in haemodialysis and renal transplant patients

SUMMARY: Blood pressure (BP) elevation and left ventricular hypertrophy (LVH) are important factors in the high cardiovascular mortality on the renal replacement programme. the relationship between these, predictable in essential hypertension, is less well defined in uraemia. We wished to examine the contribution of abnormal blood pressure variability (BPV) to the cardiovascular changes seen in uraemia and after renal transplantation. Twenty-four hour ambulatory blood pressure monitoring (ABPM), and simultaneous echocardiography, on a cohort of 35 long-term, long-hours haemodialysis survivors and 28 patients with stable renal transplants was undertaken. We also retrospectively compiled biochemical and clinical data. There were strong relationships between both diurnal and standard deviation measures of BPV and left ventricular cavity size and function: per cent fall in awake to asleep diastolic BP with fractional shortening index (FSI), r =0.28, P =0.039; with left ventricular mass index (LVMI), r =−0.35, P =0.011. This study suggests that reduced diurnal and short-term BP variability is cross-sectionally associated with a dilated, heavier left ventricle (LV) with worse systolic function. Thus, BPV may independently contribute to the abnormal LV structure and function commonly seen in uraemia.