The complex crosstalk between inflammatory cytokines and ventricular arrhythmias.

The network of cytokines consists one of the most extensively studied signaling systems of human body. Cytokines appear to modulate pathogenesis and progress of many different diseases in the human body, particularly in regards to cardiovascular system. However, their effects on the electrical system of the heart has been neglected. Over the past decade, attemps to understand this relationship led to the uncovering of the direct and indirect effects of cytokines on action potential propagation and cell depolarization. This relationship has been depicted in clinical practice as serum levels of cytokines are increasingly associated with prevalence of ventricular arrhythmias either isolated or secondary to either a heart condition or a systemic auto-immune disease. Thus, they present an appealing potential as a biomarker for prediction of arrhythmia generation, as well as the ourtcome of electrophysiological interventions.

Atrioventricular node modification in patients with chronic atrial fibrillation: role of morphology of RR interval variation.

BACKGROUND: This study evaluates the role of RR interval distribution pattern as an outcome predictor of radiofrequency (RF) modification of atrioventricular (AV) node in chronic atrial fibrillation (AF) and attempts to elucidate the likely mechanism of rate control. METHODS AND RESULTS: Sixty-five patients with chronic AF underwent AV node modification. The RR interval distribution pattern was derived from 24-hour ECG recordings obtained before and after the procedure. The preablation pattern was bimodal (B) in 36 patients (55%) and unimodal (U) in 29 patients (45%). After the modification procedure, the B pattern shifted to U (78%) or became modified B (22%). The mean number of RF pulses delivered and the fluoroscopy time were n=8+/-5 and 24+/-11 minutes, respectively, in patients with B pattern versus n=18+/-7 and 45+/-17 minutes in patients with U pattern (P<0.001 for both). The location of successful ablation was posteroseptal and lower midseptal in 26 patients (81%) with B pattern versus 2 (13%) with U pattern (P<0.001). Mean and maximal ventricular rates and heart rate at peak exercise were reduced after the procedure in both groups (P<0.001 for all). Long-term success rate, AV block incidence, and pacemaker implantation rate were 89%, 0%, and 8%, respectively, in patients with B pattern versus 52% (P<0.001), 21% (P=0.006), and 48% (P<0.001) in patients with U pattern. CONCLUSIONS: RF modification of the AV node is expected to be more effective, safe, and expeditious in patients with chronic AF and B RR interval distribution pattern. Posterior atrionodal input ablation may be the prevailing mechanism of rate control in these patients, whereas U-pattern patients may benefit from partial injury to the AV node.

A noninvasive method for the detection of dual atrioventricular node physiology in chronic atrial fibrillation.

Considering the electrophysiologic study as a reference, the RR interval distribution analysis is a sensitive (88%) and specific (80%) noninvasive method for detecting dual atrioventricular (AV) node physiology. This method may prove useful in selecting patients with atrial fibrillation who are considered appropriate candidates for radiofrequency modification of AV nodal conduction as opposed to AV nodal ablation.