| Popis: |
Background: Hemodynamically optimal atrioventricular (AV) delay can be derived by echocardiography or beat-by-beat blood pressure measurements, but analysis is labor intensive. Laser Doppler perfusion monitoring measures blood flow and can be incorporated into future implantable cardiac devices. Objective: To assess whether laser Doppler can be used instead of blood pressure to optimize AV delay. Methods: 58 patients underwent 94 AV delay optimizations using laser Doppler and simultaneous non-invasive beat-by-beat blood pressure. Optimal AV delay was defined using a curve of hemodynamic response to switching from AAI (reference state) to DDD (test state) at several AV delays (40, 80, 120, 160, 200, 240 ms), with automatic quality control checking precision of the optimum. Five subsequent patients underwent an extended protocol to test the ability of greater numbers of alternations to improve optimization quality. Results: 55/94 optimizations passed quality control: optimal AV delay on laser Doppler was similar to that derived by blood pressure (median absolute deviation 12ms).The extended protocol showed that increasing the number of replicates consistently increased quality and reduced disagreement between laser Doppler and blood pressure optima. With only 5 replicates, no optimization passed quality control, and median absolute deviation would be 29ms. These improved progressively until at 50 replicates, all optimizations passed quality control and median absolute deviation was only 13ms. Conclusions: Laser Doppler perfusion produces hemodynamic optima equivalent to blood pressure. Quality control can be automatic. Adding more replicates, consistently improves quality. Future implantable devices could use such methods to dynamically and reliably optimize AV delays. |
