| Abstract: | Background Heart rate turbulence (HRT) is a new and auspiciousparameter for risk stratification in patients suffering from structural heartdisease. The HRT parameters onset (TO) and slope (TS) are derived fromHolter ECGs. Only a few studies have evaluated physiologic properties likeage or prematurity of the ventricular beat on HRT. Until now, to our knowledge,little is known about the influence of the point of origin of the prematurebeat on HRT. Therefore, we conducted a study consisting of 25 patients(pts) with premature beats generating from 2 different sites in the atrium andventricle. Methods During an electrophysiologic study, premature extrabeats were induced. The high right atrium (HRA) and the lateral part of thecoronary sinus (CS) represented the atrial pacing sites, while the right ventricularapex (RVAP) and right ventricular outflow tract (RVOT) representedthe ventricular pacing sites. Prematurity started at 450 ms and was decreasedto the refractoriness of each site. TO and TS were computed and correlated tothe site of origin and the coupling interval (CI). Results Atrial TO was positivein 9 pts (HRA) and 7 (CS) as well as ventricular TO in 2 pts, respectively.TO induced in CS correlated with the CI (r = –0.50, p < 0.05). TS was negative,independent of the site of origin. Atrial TS showed no correlation withthe CI. TO generated from both ventricular sites was positive in 2 pts. TO fromRVAP correlated with the CI (r = –0.81, p < 0.005), but not with RVOT. TSfrom both ventricular sites exhibited no correlation with the pacing site, butcorrelated with themselves (r = –0.69, p < 0.03). Conclusion The site of originof the premature beat exhibits no influence on heart rate turbulence slope.The prematurity of the extra beat correlates with turbulence onset, but notwith slope. Finally, the site of origin revealed no influence on HRT slope.Therefore, the calculation of heart rate turbulence derived from extra beatsextracted from Holter ECG is reliable. |
