Regurgitant Fraction Measured by Using the Proximal Isovelocity Surface Area Method in Dogs with Chronic Myxomatous Mitral Valve Disease

Abstract

Previous studies have demonstrated that regurgitant fraction can be measured by using the proximal isovelocity surface area (PISA) method. For this study, we utilized this Doppler echocardiographic method to estimate the magnitude of mitral regurgitation in dogs with myxomatous mitral valve disease. Seventeen older, small dogs with chronic mitral regurgitation and no to mild myocardial failure were studied. A blinded observer judged the clinical severity of mitral regurgitation to be mild, moderate, or severe by using echocardiographic assessment of left heart size. The regurgitant fraction was calculated by using the PISA method and spectral Doppler echocardiography. The regurgitant fraction was compared to the clinical assessment of severity for each dog and to calculations of left atrial size. Five dogs had clinically mild mitral regurgitation. Four of these dogs had a regurgitant fraction between 22 and 41%, whereas 1 had a regurgitant fraction of 73%. The 3 dogs with clinical evidence of moderate mitral regurgitation had a regurgitant fraction of 46-65%. All 9 dogs with clinically severe mitral regurgitation had a regurgitant fraction greater than 75% (78-88%). The regurgitant fraction was statistically different between each group (P < .001). A good but curvilinear relationship was found between left atrial size and regurgitant fraction (r2 = 0.72). In this study, dogs with clinically severe mitral regurgitation consistently had hemodynamically severe regurgitation (regurgitant fraction > 75%), whereas dogs with clinically mild to moderate disease had lesser degrees of regurgitation. Good correlation was found between regurgitant fraction and left atrial size. We conclude that the major determinant of left atrial size and disease severity in dogs with mitrial regurgitation is the degree of mitral regurgitation.

Use of discriminant analysis based on echocardiography for classification of congestive heart failure in dogs with myxomatous mitral valve disease

“…In addition, one study demonstrated that the LA/Ao ratio was correlated significantly with the regurgitation fraction obtained by PISA (Gouni et al, 2007). In our study, the RF PISA showed higher values for group III (68.380% ± 16.153%) and the literature reports that values greater than 50% should be considered significant in cases of moderate to severe MR (Gouni et al, 2007), with values greater than 75% considered severe in small dogs (Kittleson and Brown, 2003 (Choi et al, 2004).…”

“…This fact is reported in the literature as a result of MR worsening, leading to the onset of signs of CHF (Carlsson et al, 2009). Moreover, the severity of MR is a major determinant of LA size in small animals (Kittleson and Brown, 2003). The LA/Ao ratio was greater in group III compared with the other groups; this could be justified by the fact that this ratio is directly influenced by the increase in the left atrium.…”

“…The mitral regurgitation area (MRA), vena contracta (VC) diameter and regurgitant fraction of proximal isovelocity surface area (RF PISA) were obtained from color flow mapping (Doppler) from the left apical four-chamber view, as described by previous studies (Kittleson and Brown, 2003;Muzzi et al, 2003;Gouni et al, 2007). For obtaining RF PISA, the color flow Doppler jet of mitral valve regurgitation was first identified with optimal gain setting.…”

Comparative Adverse Cardiac Effects of Pimobendan and Benazepril Monotherapy in Dogs with Mild Degenerative Mitral Valve Disease: A Prospective, Controlled, Blinded, and Randomized Study

“…Last, aortic stroke volume was assessed by pulsed wave Doppler trace of the aortic flow velocity by multiplying the aortic area by the velocity time integral using the left apical 5-chamber view. 23 …”

Effects of Pimobendan for Mitral Valve Regurgitation in Dogs

“…The regurgitant stroke volume (RSV) and the effective regurgitant orifice (ERO) were estimated by the proximal isovelocity surface area (PISA) method, which estimates regurgitation volume quantitatively [4,5,11].…”