Session PC1.2

Clinical Monitoring of the Tilt-Test: Task Force Monitor (TFM) and Heart Rate Variability (HRV)

F Marangoni*, I Corazza, MC Tozzi, J Frisoni,
ML Bacchi Reggiani, R Zannoli

Università di Bologna
Bologna, Italy

In the management of syncope, the study of the heart rate variability, using autoregressive analysis (AR) during tilt test, represents the leading approach to evaluate the sympathetic and vagal balance of the autonomic nervous system. In clinical practice, Tilt Test is performed with traditional instrumentations (Grass Poligraph, Light® Workstation, GRPSD software, Spark S.r.l Bologna.) or with apparatuses of new generation like the Task Force Monitor (TFM, CNSystems Medizintechnik GmbH). GRPSD software allows a very accurate and complete step by step spectral analysis of the signals from the signal steadiness and noise rejection to the choice of the order of autoregressive model. The procedure is quite complex and can be made only during post-processing phase by a skilled operator. On the contrary the TFM, analyses the ECG signals and presents autoregressive analysis in real time, but it is “closed” and it is not possible to set the mathematical parameters (i.e. model order). The aim of this study was to compare the two systems and verify the consistency between the AR analysis performed with TFM and GRPS. Nine patients have been submitted to Tilt Up Test and monitored in parallel using TFM and GRPSD systems. Tachogram signals have been exported in ASCII format from TFM and analysed with the GRPSD software. The same periods were analysed with both the system and the LF and HF components (0, 04 Hz – 0, 15 Hz; 0, 15 Hz – 0, 4 Hz) were calculated. The ratios between LF and HF (LF/HF-TFM e LF/HF-GRPSD ) were evaluated for TFM and GRPSD and the concordance between them was verified. Statistical analysis showed an agreement between the ratios LF/HF in the 82% of the cases. The 18% of mismatches are due to a wrong AR model order, the a non correct discrimination of the respiratory artefacts and to the unsteadiness of the signals analysed by the TFM. Despite TFM is very “user friendly” system which performs sophisticated analyses, sometimes it gets to wrong results because of the incorrect application of the AR analysis algorithm. The system is “closed” and it is impossible for the operator to verify the correctness of the procedure steps and the result is a “reject or accept” choice, based on pure confidence!.

(Abstract Control Number: 179)