Acoustic Cardiography: New Technique for Resynchronization Device Optimization May Provide Improved Outcomes
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September 21, 2007 By Grendel Burrell [1]
Lucerne, Switzerland: Dr. Stefan Toggweiler et al assessed the optimization of AV and VV delays in implanted resynchronization devices with objective clinical and hemodynamic parameters using acoustic cardiography and compared these to the “out of the box” settings in 14 patients, at a single center in Lucerne, Switzerland and presented their data as a poster at HFSA 2007 in Washington, DC. Currently, there are no ACC/AHA or HRS guidelines for the optimization of these devices. An informal survey of approximately 15 physicians representing divergent geographic areas showed wide variation in the role of device optimization. Practice ranges from optimizing no one to only optimizing the “non responders” to optimizing all patients prior to discharge post implant and on a regular basis.
All patients in the report by Toggweiler et al were approximately 15 months post implant, and 86% were male. The mean age of the patients was 64+/-9 years. Spiroergometry and 2D/3D echocardiography were used to assess cardiac performance for the standard “out of the box” settings compared to optimized settings determined by acoustic cardiography (AUDICOR®, Inovise Medical, Portland, OR). All patients were assessed at baseline with spiroergometry and 2D/3D echo, and then assessed for optimal AV/VV settings determined by the lowest electromechanical activation time (EMAT, the time from the onset of QRS to the mitral valve component of the first heart sound), the appearance of and strength of the S3, and the LVST (left ventricular systolic time interval). Statistical analysis was performed using a paired two-tailed Student’s t-test.
Use of the optimization technique using acoustic cardiography resulted in statistically significant improvements in multiple parameters including work capacity, peak oxygen uptake, peak oxygen pulse, ejection fraction, end systolic volume, and LVOT-VTI. Acoustic cardiography may offer additional advantages in that the procedure can be accomplished in <15 minutes whereas optimization with echo can take 30 minutes to 2 hours and is more personnel intensive. Physicians at HFSA frequently commented that one barrier to regular optimization of patients with devices is the burden on the echo lab and staff time required to determine the device settings. Physicians and nurses are interested in ways to incorporate optimization into workflow in the office and clinics.
