AUTOMATED TRACKING OF LEFT-VENTRICULAR WALL THICKENING WITH INTRACARDIAC ECHOCARDIOGRAPHY

Objective. We developed and evaluated a new method to automatically me asure regional left ventricular wall thickening by analyzing the radio frequency backscatter signal from an intracardiac echocardiographic ca theter. Methods. We inserted 10-MHz echocardiographic catheters in 11 dogs. Wall thickness was perturbed by altering loading conditions and inotropic state. The backscatter signal from a single selected radial scan line was digitized. An automated algorithm identified the digitiz ed endocardial and epicardial signals, tracked them throughout the car diac cycle, and plotted the spatial difference over time. Pressure-thi ckness loops were generated. Results. End-systolic and end-diastolic t hickness and percent wall thickening from the unedited, unsmoothed sig nals compared favorably with independent manual analysis of transthora cic echocardiographic images of the same region: r = 0.89 for wall thi ckness and 0.81 for systolic thickening. Conclusion. The backscatter s ignal from an intracardiac echocardiographic device can be analyzed au tomatically to continuously assess regional left ventricular wall thic kening and generate pressure-thickness loops.