Automatic optimization of resting and exercise atrioventricular interval using a peak endocardial acceleration sensor: Validation with Doppler echocardiography and direct cardiac output measurements

Peak endocardial acceleration (PEA) measured by an implantable acceleration sensor inside the tip of a pacing lead reflects ventricular filling and my ocardial contractility. The contribution of the plateau phase of PEA as an indicator of optimal ventricular filling, hence of the appropriate atrioven tricular interval (AVI) at rest and during exercise, was studied in 12 pati ents (age 69 +/- 6 years) with complete AV block and a PEA sensing DDDR pac emakers (Living 1 Plus, Sorin Biomedica). At a mean resting heart rate of 7 9 +/- 15 beats/min, the mean AVI optimized by PEA versus Doppler echocardio graphy (echo) were identical (142 +/- 37 vs 146 +/- 26 ms, P = 0.59). Durin g submaximal exercise at a mean heart rate of 134 +/- 6 beats/min, AVI opti mized by PEA was 135 +/- 37 ms. Cardiac output at rest, measured by the CO2 rebreathing method, was comparable with AVI determined by echo versus PEA (4.3 +/- 2.9 and 3.7 +/- 2.4 L/min, respectively), and increased to the sam e extent (8.0 +/- 3.9 vs 8.3 +/- 5.2 L/min) during submaximal exercise. in patients with AV block, AVI automatically set by PEA was comparable with AV I manually optimized by Doppler echocardiography and was associated with co mparable exercise induced hemodynamic changes.