Abstract 14069: A Three Dimensional Accelerometer Can Monitor Left Ventricular Function Independent of Sensor Alignment with the Cardiac Coordinate Axes
Introduction: Technological advances may allow development of multifunctional pacemakers with incorporated accelerometers aimed to provide continuous information on LV function. Circumferential motion by accelerometer is a sensitive parameter for LV function. However, a condition for this is alignment of the sensor to the cardiac coordinate system.
Hypothesis: Alignment of the sensor can be avoided by using a 3 axis (3D) accelerometer.
Methods: In 20 open-chest pigs a miniaturized 3D accelerometer was fixed on LV in the left anterior apical region. Accelerations (sampling rate 500 Hz) in circumferential, longitudinal and radial directions were continuously measured. From these signals an epicardial 3D velocity vector was calculated. Peak 3D systolic velocity (3D Vsys) were compared to LV dP/dtmax and peak circumferential systolic velocity (Circ Vsys), also obtained by the accelerometer, during changes in global LV function (epinephrine, esmolol and fluid loading) and regional LV function (LAD occlusion for 3 min).
Results: Significant and typical changes in accelerometer 3D Vsys and Circ Vsys were seen in global and regional interventions (Figure A-B). Both 3D Vsys and Circ Vsys reflected LV contractility by correlating significantly to LV dP/dtmax during global interventions, r2=0.98 and r2 =0.97 respectively (both P<0.001). ROC analysis demonstrated excellent and similar sensitivity and specificity of accelerometer 3D and Circ Vsys to discriminate LAD occlusion from global interventions with sensitivity and specificity of 0.90 and 0.92 (cut-off value 3.3 cm/s) for 3D Vsys and 0.90 and 0.88 (cut-off value 7.0 cm/s) for Circ Vsys.
Conclusion: Accelerometer 3D Vsys and Circ Vsys were clinical relevant indices of global and regional LV function. Alignment of the sensor with the cardiac coordinate system was not needed by use of 3D data. Multifunctional pacemakers with incorporated 3D accelerometers may be a future method for monitoring LV function.
- © 2012 by American Heart Association, Inc.