Radius of proximal isovelocity surface area in the assessment of rheumatic mitral stenosis: connecting flow to anatomy and hemodynamics

Echocardiographic assessment of left atrial pressure [LAP] in mitral stenosis [MS] is controversial. We sought to examine the role of the radius of the proximal isovelocity surface area [PISA-r] in the assessment of the hemodynamic status of MS after fixing the aliasing velocity [Val]. We studied 42 candidates of balloon mitral valvuloplasty [BMV], for whom pre-BMV echocardiography was done and LAP invasively measured before dilatation. PISA-r was calculated after fixing aliasing velocity to 33 cm/s. In addition, the ratio IVRT/Te'-E was also measured, where IVRT was isovolumic relaxation time, and Te'-E was the time difference between the onset of mitral flow E-wave and mitral annular early diastolic velocity. IVRT/Te'-E and PISA-r showed a strong correlation with LAP [r= -0.715 and -0.637, all p < 0.001] and with right-sided pressures. In addition, PISA-r correlated with mitral valve area by planimetry method [MVA] and with left ventricular outflow tract stroke volume [r = 0.66 and 0.71, all p < 0.001]. Receiver operator characteristic curve [ROC-curve] showed that PISA-r was not inferior to IVRT/Te'-E in differentiating LAP >/=25 from <25 mmHg. Provided that Val is set to a constant of 33 cm/s, PISA-r can assess the hemodynamic status of MS, and seems a simple alternative to the tedious IVRT/Te'-E for estimation of LAP

Simplifying proximal isovelocity surface area as an assessment method of mitral valve area in patients with rheumatic mitral stenosis by fixing aliasing velocity and mitral valve angle

We aimed to test the ability of a simple equation using proximal isovelocity surface area method [PISA], created by fixing the angle to 100° and the aliasing velocity to 33 cm/s, to calculate mitral valve area [MVA] and assess severity in patients with rheumatic mitral stenosis [MS]. In a series of 51 consecutive patients with rheumatic MS, MVA was assessed by four methods, conventional PISA equation PISA[conventional], simple PISA equation PISA[simple], pressure half time [PHT], and planimetry [PLN] which was taken as the reference method. All methods correlated significantly with PLN with the highest correlation found in case of PISA[conventional] and PISA[simple] [r = 0.97, 0.96, p < 0.001], while the correlation in case PHT was relatively weaker [r = 0.69, p < 0.001]. Bland-Altman analysis revealed that the level of agreement with PLN was better in case of both PISA methods than PHT and, moreover, were close to each other. The number of cases that showed agreement of severity grade with planinetry was better in case of PISA[conventional] [42 cases] and PISA simple [44 cases] than that in case of PHT [34 cases, p = 0.037]. Finally, the measure of agreement with Cohen's Kappa test was better in case of PISA[conventional] and PISA[simple] than that in case of PHT. Provided that aliasing velocity is fixed at 33 cm/s, PISA can effectively predict mitral valve area and severity of MS by a simple equation, with the advantage of easy and accurate calculation over other methods