© 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
CP17: OPTIMIZATION OF THE AV DELAY IN CARDIAC RESYNCHRONIZATION THERAPY USING AN IMPLANTED HEMODYNAMIC MONITOR
1Department of Cardiology, Karolinska University Hospital Stockholm, Sweden; 2CRM Research, Medtronic Bakken Research Center Maastricht, Netherlands
PURPOSE: Optimization of AV timing is important in heart failure(HF) patients treated with cardiac resynchronization therapy(CRT). An implanted hemodynamic monitor(IHM) can be used for continuous recording of cardiac filling pressures in HF patients. We hypothesized, that the IHM might be helpful in identifying the optimal AVdelay.
METHODS: 10 patients with heart failure, successfully treated by CRT(InSync III®), (LVEF 24±9%, LVEDD 64±11mm) were also implanted with an IHM (Chronicle®, Medtronic Inc) that continuously records RV systolic/diastolic pressures and an estimation of the pulmonary artery diastolic pressure (PAD), reflecting left atrial filling pressures. The IHM consists of a memory device and a RV lead with a pressure sensor. First, AV delays were optimized by echo (Ritter method). Then, different AV-delays (50-190 ms) were randomly programmed using steps of 20 ms. The PAD was calculated as a 20s median, 40-60s after programming was changed. A low PAD value was considered optimal. Measurements were repeated 1 week later under the same conditions. The Mann-Whitney U test was used to compare differences within the groups.
RESULTS: No adverse events were associated with dual device implant. One patient was excluded due to AF. Using the IHM, a U-shaped curve was obtained, indicating an optimal AV delay slightly longer as compared with echo. Shortening the AV interval resulted in increased PAD (Tab. 1). The relatively low PAD at +60 ms may be associated with fusion beats at longer AV-delays. These observations were consistent in the repeated tests.
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CONCLUSIONS: The IHM was helpful in identifying the optimal AV-delay in HF patients treated with CRT. In the future, a hemodynamic sensor may be incorporated in CRT devices for long-term recording of filling pressures and allow for hemodynamic device optimization during daily living activities.