Dynamic on-line quantification of biventricular function with acoustic quantification (AQ). Validation, reproducibility and normal values of a new echocardiographic approach.

Abstract

OBJECTIVES: Acoustic quantification (AQ), a recently developed ultrasonic integrated backscatter imaging system providing on-line measurements of ventricular cavity areas and their functional indexes, was validated in comparison to angiography and Doppler derived systolic dP/dt. Normal AQ-reference values were established. METHODS AND RESULTS: 1. In 45 patients undergoing heart catheterization, AQ derived areas in end-diastole (EDA), end-systole (ESA) and the resulting fractional area change (FAC) in apical 2- and 4-chamber view were compared to the corresponding biplane angiographic data. All correlations yielded significant values (p < 0.0001; EDA: r = 0.90, SEE = 2.6 cm2; ESA: r = 0.91, SEE = 2.2 cm2; FAC: r = 0.90, SEE = 4.1%). However, AQ-areas were underestimated by about 25%. 2. In 36 patients with mitral regurgitation AQ-FAC and AQ derived systolic dA/dt were compared to the Doppler derived systolic dP/dt, yielding significant correlations with r = 0.91 and r = 0.87; p < 0.0001. 3. In 50 healthy subjects, AQ derived EDA, ESA and FAC averaged 25.7 +/- 4.9, 14.7 +/- 3.3 cm2 and 43.2 +/- 4.8% for the left, and 17.1 +/- 3.8, 9.0 +/- 2.9 cm2 and 47.3 +/- 9.2% for the right ventricle. For EDA normalized peak filling (PFR) and ejection rates (PER) yielded 2.7 +/- 0.28 and -2.4 +/- 0.42 EDA/sec for the left and 3.4 +/- 0.74 and -2.9 +/- 0.62 EDA/sec for the right ventricle. The interobserver and day-to-day variability of AQ in healthy subjects and cardiac patients was low for EDA, ESA and FAC (< 12%) and higher for PFR and PER (< 20%). CONCLUSION: In comparison to angiography AQ reliably quantitates on-line left ventricular fractional area change, although AQ-areas are underestimated. AQ offers reproducible values of systolic and diastolic function and a new approach to cardiac patients.