The influence of mental and physical stress on the autocapture function in children.

The Autocapture function detects the evoked response signal (ERS) to verify beat-to-beat capture, and optimizes the output of ventricular pulse amplitude automatically. We had experience concerning the instability of the Autocapture recommendation in some patients. Evoked response is subject to variation as it is a biological event. However, the present knowledge about the Autocapture function lability is very limited. The purpose of this study was to evaluate whether mental stress, body positions or exercise influence the ERS and PS in children. Study was performed in 15 consecutive patients [13.4 +/- 4.1 (5-20) year] with VVIR (n = 10) and DDD/VDD pacemakers with the Autocapture function (n = 5), had received ventricular leads including Membrane-E-1450T (n = 6), Membrane-EX-1470T (n = 2), Tendrill-DX-1388T (n = 3), Tendrill-SDX-1488T (n = 1), AV-Plus-DX-1368 (n = 1), Accufix-II-DEC (n = 1) and Vitatron (n = 1), and followed more than six months. Autocapture functions were measured during arithmetic mental stress test (MST), in different body positions, and during symptom-limited treadmill exercise. MST was applied in all except two (5 and 8 year old) who didn't have ability to perform. Activating autocapture was not recommended in only one with Accufix-II-DEC due to high PS. ERS was 10.5 +/- 6.3 mV during supine and increased to 11.9 +/- 7.5 mV during sitting (p = 0.017) and standing 12.1 +/- 7.2 (p = 0.002). However, ERS remained stable before, during and after both exercise and MST, which were 12.6 +/- 7.2 mV, 12.8 +/- 7.8 mV, 13.6 +/- 9.4 mV (p > 0.05) and 10.5 +/- 5.5 mV, 10.9 +/- 6.7 mV, 10.4 +/- 5.5 mV (p > 0.05) respectively. In addition, PS and recommendation about the Autocapture remained unchanged during the study. In conclusion, MST, different body positions and exercise do not have any clinically important influence on the Autocapture function in children.