Key result
Orthostasis during tilt-table testing increased the plateau amplitude of the ventricular-evoked response, and repolarization time correlated inversely with heart rate (r = -0.78).
Why the study?
Does orthostasis affect the ventricular-evoked response in patients with pacemakers?
Observational (n=7)
Does orthostasis affect the ventricular-evoked response in patients with pacemakers?
Effect estimate: r = -0.78
Orthostasis alters the ventricular-evoked response in pacemaker patients, with plateau amplitude increasing in the upright position and repolarization time shortening with higher heart rates.
Orthostasis may modify ventricular-evoked responses in pacemaker patients; leaves open need for prospective outcome studies.
AIMS: The effects of orthostasis on the morphology of the ventricular-evoked response were investigated. METHODS AND RESULTS: Seven patients (five females; 74.9 +/- 4.6 years) with second- or third-degree atrioventricular block received DDD pacemakers Physios CTM 01 with fractal-coated ventricular leads (both Biotronik, Germany). At their 3-month follow-up sessions, these patients underwent tilt-table tests. Heart rate, mean arterial blood pressure and ventricular-evoked response were measured continuously. Signals were averaged over 15 consecutive beats. Coefficients of correlation between selected ventricular-evoked response parameters and heart rate or mean arterial blood pressure were calculated. Tilt upwards affected heart rate, mean arterial blood pressure and ventricular-evoked response extremes showed non-uniform, patient-specific changes that were not related directly to other parameters. Heart rates significantly increased in six patients following tilt upwards. For all patients, ventricular-evoked response plateau amplitudes immediately increased with tilt upwards. Furthermore, repolarization times correlated with changes in heart rates (r = -0.78). CONCLUSIONS: Monitoring of the ventricular-evoked response during tilt-table testing revealed that the plateau amplitude of the ventricular-evoked response depends on the patient's position; ventricular-evoked response increased in the upright position and decreased in the supine position. Furthermore, repolarization time and heart rate correlated inversely; higher heart rates resulted in a shortening of the ventricular-evoked response.
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F. Saborowski (2000) conducted an observational in Second- or third-degree atrioventricular block (n=7). Orthostasis (tilt-table testing) vs. Supine position was evaluated on Ventricular-evoked response morphology (plateau amplitude and repolarization time) (r = -0.78). Orthostasis during tilt-table testing increased the plateau amplitude of the ventricular-evoked response, and repolarization time correlated inversely with heart rate (r = -0.78).