HEART-RATE RESPONSE TO VENTRICULAR STIMUL ATION

Analysis of heart rate variability (HRV) by Hotter monitoring is the m ethod of choice for assessing the cardiac autonomic regulation. Rapid ventricular stimulation also provokes changes in the autonomic nervous system tone. The aim of this study was to compare time and frequency domain analysis of HRV (Elatec version 3.02) with variations of HR obs erved after incremental ventricular stimulation to 200/min in 130 pati ents. In 80 patients, ventricular stimulation provoked an initial acce leration in HR followed by a slowing with a variation of over 10 %. In the other 50 patients, these variations were not,observed. Holter ana lysis of HRV showed concordance between the two methods. In time domai n analysis, the standard deviation of normal R-R intervals, the coeffi cient of variability [(CV = SD/mean RR) and percentage of adjacent RR intervals with a difference of more than 50 msec (pNN 50) were signifi cantly reduced in the abnormal group, the respective values in the nor mal and abnormal groups being : SD 122 vs 72 msec; CV 15 versus 9 % an d pNN50 9 Versus 5 %)]. In frequency domain analysis, there was a redu ction of low and high frequency;spectra and of the ratio of low/high f requencies in abnormal subjects. The authors conclude that the disappe arance of HR changes after ventricular stimulation is correlated to th e absence of HRV on Holter recording. This simple test may be performe d systematically during electrophysiological investigations. The measu rements are reproductible and the results are not affected by arrhythm ias or technical problems of quality recording by the Hotter method wh ich may affect analysis of HRV.