Quantification of mitral regurgitation using proximal isovelocity surface area method in dogs

The present study was performed to determine the accuracy and reproducibility of calculating the mitral regurgitant orifice area with the proximal isovelocity surface area (PISA) method in dogs with experimental mitral regurgitation and in canine patients with chronic mitral insufficiency and to evaluate the effect of general anesthesia on mitral regurgitation. Eight adult, Beagle dogs for experimental mitral regurgitation and 11 small breed dogs with spontaneous mitral regurgitation were used. In 8 Beagle dogs, mild mitral regurgitation was created by disrupting mitral chordae or leaflets. Effective regurgitant orifice (ERO) area was measured by the PISA method and compared with the measurements simultaneously obtained by quantitative Doppler echocardiography 4 weeks after creation of mitral regurgitation. The same procedure was performed in 11 patients with isolated mitral regurgitation and in 8 Beagle dogs under two different protocols of general anesthesia. ERO and regurgitant stroke volume (RSV) by the PISA method correlated well with values by the quantitative Doppler technique with a small error in experimental dogs (r = 0.914 and r = 0.839) and 11 patients (r = 0.990 and r = 0.996). The isoflurane anesthetic echocardiography demonstrated a significant decrease of RSV, and there was no significant change in fractional shortening (FS), ERO area, LV end-diastolic and LV end-systolic volume. ERO area showed increasing tendency after ketamine-xylazine administration, but not statistically significant. RSV, LV end-systolic and LV end-diastolic volume increased significantly (p < 0.01), whereas FS significantly decreased (p < 0.01). The PISA method is accurate and reproducible in experimental mitral regurgitation model and in a clinical setting. ERO area is considered and preferred as a hemodynamic-nondependent factor than other traditional measurements.

Quantitative Evaluation of Regurgitant Volume in the Patients with Mitral Regurgitation Using Color Doppler Proximal Isovelocity Surface Area Method

BACKGROUND: The Evaluation of valvular regurgitation is a long standing clinical problem. While many ways to evaluate the severity of valvular insufficiency have been tried, none allows precise quantification of regurgitation volume. Invasive angiographic grading of mitral regurgitation is semiquantitative and subjective. Recent studies have shown that using color Doppler flow mapping can identify a blue-red aliasing radius, corresponding to a proximal isovelocity surface area(PISA), proximal to a regurgitant orifice. Thus regurgitant volume across the mitral orifice can be calculated. METHODS: The clinical applicability of the PISA method was evaluated prospectively in 23 patients with mitral regurgitation and also the regurgitant volume calculated by using the time-velocity integral(TVI) method. The regurgitant jet area were compared to regurgitant volume calculated from the PISA method. RESULTS: 1) Regurgitant volume calculated by using the PISA method correlated well with the regurgitant volume calculated by using the TVI method(r=0.73, P=0.0001). 2) Regurgitant volume calculated by using the PISA method did not correlate with the regurgitant jet to left atrial ratio(r=-0.02, P=0.94). 3) Eccentricity of regurgitant flow did not influence the result of PISA method. CONCLUSIONS: It is concluded that PISA method by color Doppler flow imaging is simple and useful noninvasive method for the quantitative evaluation of mitral regurgitant volume.