DYNAMIC ONLINE QUANTIFICATION OF LEFT-VEN TRICULAR FUNCTION WITH AUTOMATED BORDER DETECTION (ABD) - VALIDATION OF A NEW ECHOCARDIOGRAPHIC APPROACH

A recently developed ultrasonic integrated backscatter imaging system allows automated border detection (ABD) of the blood-tissue interface in real time and provides instantaneous measurement of left ventricle cavity area in a beat-to-beat fashion. Three validations of this new s ystem have been performed. 1) In 70 subjects (38 normal volunteers and 32 patients) the on-line ABD-derived areas (end-diastole, -systole = EDA, ESA) and the resulting fractional area change (FAC) of the left v entricle (apical four-chamber view) were compared with the off-line ar eas and FAC traced manually. All correlations were close (EDA r= 0.97, ESA r = 0.98, FAC r = 0.92; p < 0.0001). 2) In 36 patients with mitra l regurgitation (MR), ABD-FAC was compared to the Doppler-derived syst olic rate of pressure rise (RPR) which corresponds to systolic dP/dt, as simultaneous studies with high-fidelity pressure measurements have shown. Linear regression analysis yielded a significant correlation wi th r = 0.91; p < 0.0001. 3) In 26 patients undergoing routine heart ca theterization, ABD-echo was performed on the same day. ADD-derived are as (end-diastole, -systole) and FAC (apical two- and four-chamber view ) were compared to the corresponding angiographic data derived from bi plane projection in 30 degrees RAO and 60 degrees LAG. Linear regressi on analysis yielded significant values for all correlations (EDA r = 0 .88, ESA r = 0.95, FAC 0.90; p < 0.001). However, ABD-areas were signi ficantly underestimated by about 30%. Conclusion: 1) ABD measurement o f FAC appears to be a reliable non-invasive on-line method for quantif ication of systolic ventricular function. However, ABD-derived areas a re underestimated in comparison to angiography. 2) Although ABD-detect ion of cavity borders is automatic and therefore less subjective,the m ethod is gain-dependent and requires accurate adjustment of gain setti ngs.