Quantification of left ventricular volumes by two-dimensional echocardiography: A simplified and accurate approach
A new and simplified method to determine left ventricular (LV) volumes with two-dimensional echocardiography (2-D echo) was developed using the parasternal long-axis and apical four- and two-chamber views. An end-diastolic area (EDA) was derived using the longest minor axis (D(max)) from either of the three views and the major long axis (L(max)) from the apical views, with the formula EDA = D(max).L(max). π/4. LV end-diastolic volumes (EDVs) obtained by single-plane angiograms were correlated with the EDAs derived from 2-D echo in 25 initial patients and the resultant equation, EDV = (EDA x 4.35) - 6.44 (r = 0.82, SEE = 34 ml), was applied prospectively to 27 patients (r = 0.95, SEE = 19 ml) and to the 52 combined patients without underestimation according to the equation y = 1.07 x -7.3. Twenty-nine of the 52 patients had coronary artery disease and regional dyssynergy. Ejection fraction (EF) measured with a previously validated method that uses the average of several LV dimensions correlated well with angiographic EF in the initial (r = 0.96, SEE = 5%) and prospective (r = 0.87, SEE = 8%) series and in both series combined (r = 0.92, SEE = 7%). End-systolic volume (ESV) was derived by substracting stroke volume (EDV X EF) from EDV. Correlation coefficients for 2-D echo ESV vs angiographic ESV were 0.91, 0.97 and 0.94, with SEES of 25, 12, and 19 ml for the initial, prospective and combined series, respectively. Two-dimensional echo EDV, EF and ESV also correlated well (r = 0.89-0.97) with biplane angiographic results in 15 of 27 prospective patients. Comparisons between two independent observers revealed high r values (0.958-0.965) and mean differences for EDV, EF and ESV of ±3%, ±6% and ±8%, respectively. Thus, a simplified method of determining LV volumes with 2-D echo without a need for planimetry or computer assistance has been validated.