IMPEDANCE CARDIOGRAPHY HOLTER- REOMONITOR: CLINICAL AND PHYSIOLOGICAL APPLICATIONS Gerard Cybulski 1 , Edward Koźluk 2 , Sebastian Stec 3 , Wiktor Niewiadomski 1 , (1) Dept. Applied Physiology, Medical Res.Ctr., Warsaw, Poland, gerard@cmdik.pan.pl; (2) 1 st Chair and Department of Cardiology, Medical University of Warsaw, Poland; (3) Department of Cardiology, Postgraduate Medical School, Warsaw, Poland Abstract: Impedance cardiography (ICG) enables the non-invasive, reproducible, beat-to-beat estimation of stroke volume (SV) changes, and the measurement of the absolute values of the ejection time (ET) and pre- ejection period (PEP), which allows the indirect evaluation of cardiac contractility. The miniaturised, Holter-type impedance cardiography device with built- in one channel of ECG- called ReoMonitor, was constructed. The system allows the long-term, beat-to- beat, automatic evaluation of SV, ET, PEP and heart rate (HR). The measurements obtained by ReoMonitor were verified using an echocardiographic method in supine and tilted positions in 13 subject (SVicg= 0.73*SVecho +20.13, r=0.82877, p<0.001, n=306). 330 healthy subjects and patients with hypertension, arrhythmia events or orthostatic intolerance in ambulatory conditions were monitored using this system. It was also applied to analyse the hemodynamic response to orthostatic manoeuvre, static exercise, and dynamic exercise of up to the 150 W intensity. System was used to follow the hemodynamic effects of endurance training, differences in response to orthostatic manoeuvre with age and the type of physical activity, and the 3-day bed-rest. It was demonstrated that the system might be used to collect signals in a laboratory and in the field, for monitoring both, the steady state and the transient phase of cardiovascular response to physiological tests. Speech or vigorous movement distinctly lowered the percentage of properly recognised cardiac cycles (during daytime: 20% - 80%, during the night: 75% - 90%). However, during exercise testing on a cycloergometer the quality of recordings were acceptable. The measurements of SV by ambulatory ICG and echo were significantly correlated in sinus beats and VEBs (r=0.93, and r=0.74, consecutively) in arrhythmia patients. Highly symptomatic patients at rest had significant decrease in cardiac output during bigeminy revealed both by echo and ICG measurements. ICG allowed evaluation of various haemodynamic characteristics of simple VEBs and complex arrhythmia (interpolated VEBs, bigeminy, trigeminy, couplets) during daily life, while standing and after exercise. Ambulatory impedance cardiography may serve for the optimisation of a-v delay in dual- chamber pacing systems at rest and to verify the value of this parameter during normal daily activity. Preliminary data show the possibility to use this system in the following clinical applications: a) evaluation of haemodynamical abnormalities caused by arrhythmia events, b) early diagnosis of vasovagal syncope, and c) optimisation of atrio-venticular delay during dual- chamber pacing. INTRODUCTION: The idea of impedance cardiography ambulatory monitoring with signal recording using memory chips was introduced in 1985 by the Webster’s group 1 and developed when PCMCIA Card was applied. 2 . In 1996 and 1998 two groups described another constructions. 3-4 In 2000 the portable polyphysiograph was constructed 5 and in 2001 Nakonezny et al., found ambulatory ICG as a reliable method for measurement stroke volume, cardiac output, heart rate and systolic time intervals during some psycho-physiological tests. 6 Ventricular extrasystole beats (VEB) could occur in a paroxysmal or more regular form. However, having only ECG traces, it is not possible to distinguish between hemodynamically efficient and non-efficient VEBs. Those, which are not effective could significantly decrease the SV, and in consequence CO, in comparison to sinus rhythm (SR). 7-8 If VEB is triggered by unknown factor occurring during every day activity, but not in a clinical conditions, it could be detected using ECG holter. But the level of CO decrease, with all consequences to the patient, remains not evaluated. We intended to check whether using impedance cardiography ambulatory monitoring, the hemodynamic effect of this type of the arrhythmia could be quantitatively evaluated. Dual chamber cardiac pacing (DDD) is increasingly used in the management of congestive heart failure. However, inappropriate programming of the AVD decreases cardiac output significantly. 9 Thus, AVD optimisation is 334