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  • Title: Optimal sensed atrio-ventricular interval determined by paced QRS morphology.
    Author: Van Gelder BM, Bracke FA, Van Der Voort PH, Meijer A.
    Journal: Pacing Clin Electrophysiol; 2007 Apr; 30(4):476-81. PubMed ID: 17437570.
    Abstract:
    BACKGROUND: In cardiac resynchronization therapy (CRT), the atrio-ventricular (AV) and interventricular (VV) intervals have to be optimized. For maximal optimization, the paced and sensed AV intervals have to be determined. We hypothesized that the morphology of the paced QRS complex at the optimal paced AV interval (PAV) can be used to determine the optimal sensed AV (SAV) interval in patients with normal AV conduction. PATIENTS AND METHODS: In 16 patients with implanted CRT devices, the optimal PAV and V-V interval were determined by invasive measurement of left ventricle (LV) dP/dt(max). A 12-lead electrocardiogram (ECG) was recorded at the optimum setting. Subsequently, during atrial sensing ventricular pacing, the SAV interval was changed until the QRS morphology was identical to the morphology at the optimal PAV interval. The optimal SAV interval was verified by repeated measurement of LV dP/dt(max). RESULTS: By optimization of the PAV and VV interval, the LV dP/dt(max) increased from 639 +/- 204 to 789 +/- 223 mmHg/s (+23%; P = 0.0000002). The optimized PAV was 149 +/- 19 ms; the optimized SAV was 100 +/- 20 ms and the corresponding LV dP/dt(max) at this interval was 774 +/- 204 ms (+21%; P = 0.000004). LV dP/dt(max) at optimized SAV - 20 ms and optimized SAV + 20 ms was 747 +/- 213 mmHg/s (P = 0.00004) and 751 +/- 203 mmHg/s (P = 0.0000003), respectively. The mean difference in optimized PAV and optimized SAV was 49 +/- 17 ms, ranging from 20 to 80 ms. CONCLUSIONS: The QRS morphology at optimized PAV can be used as a template to determine the optimal SAV, provided that the patient has normal AV conduction.
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