DK2985_C000 1..28 - AlSharqia Echo Club

404 Transesophageal Echocardiography(A)(B)PVFIn the case of MR without associated significant aorticregurgitation (AR), the left ventricular total stroke volume(SV) is given by the SV across the mitral valve (SV mv ):SV MV ¼ 0:785 d 1 d 2 TVI MV (17:5)where d 1 is the diameter of the mitral valve annulus in thefour-chamber view; d 2 is the diameter of the mitral valveannulus in the two-chamber view or mid-commisural;and TVI MV is the time velocity integral (in cm) measuredby PWD with the sample volume in the center of the mitralvalve annulus.This equation assumes that the mitral valve annulushas an elliptical shape and requires the measurement ofthe two diameters d 1 and d 2 in orthogonal views (fourandtwo-chamber views), from inner edge to inner edgeat the base of the mitral leaflets in diastole (41). Theprecise measurement of the TVI at the mitral annulusDSYSTOLIC FLOW REVERSALFigure 17.26 Acute mitral regurgitation in a 61-year-old manwith rupture of the posteromedial papillary muscle. (A) Pulsedwaveexamination of the pulmonary venous flow (PVF)showing significant systolic flow reversal (the equivalent of a“v” wave), consistent with severe regurgitation. (B) Excisedpathology specimen. (Photo B courtesy of Dr. Yves Hébert.)level requires an optimal alignment of the ultrasoundbeam with the direction of the flow. In contrast to theLVOT, the measurement of TVI is performed at themitral annulus tracing the modal (most dense) velocityon the Doppler signal envelope, rather than the peakvelocity (outer edge of the signal). Although the measurementsof diameters for aortic and mitral valve measurementsare the most common source of error in thecalculation of volumetric flow, they were however foundto be reproducible in an individual patient (42).In the presence of significant AR, the systemic volumetricflow can alternatively be calculated at the pulmonaryvalve annulus or the pulmonary trunk.While the PISA method measures the ERO first andsecondly deducts the regurgitant volume, the continuityequation yields first the regurgitant volume and then theERO using the following equation:MR VolERO MV ¼ (17:6)TVI MRwhere ERO is the effective regurgitant orifice (in cm 2 );and TVI MR is the time–velocity integral (in cm) of themitral regurgitant signal obtained by CWD, tracing thepeak (outer edge) of the Doppler signal envelope.The regurgitant fraction is given by the followingequation:RF ¼ RegVol 100 (17:7)SV Totalwhere RF is the regurgitant fraction (in %); RegVol is theregurgitant volume (in mL); and SV Total is the total strokevolume (in mL) of the left ventricle.The regurgitant volume is obtained either by the PISAmethod or through the continuity equation. The total SV ofthe LV is obtained by volumetric measurement at the levelof the mitral valve annulus, but it can be equally measuredfrom the difference between the 2D tracing of enddiastolic(EDV) and end-systolic volumes (ESV).Determination of regurgitant volume and ERO throughthe continuity equation offers an advantage in the presenceof very eccentric jets or multiples jets, where the PISA andvena contracta method may be more difficult to perform.On the other hand, these calculations are time-consumingand require careful execution which is sometimes difficultto perform in the operating room.7. Integrated ApproachThe task force suggests a scheme of specific signs, supportiveand quantitative to help grade MR (Table 17.3). Theapproach to the evaluation of MR severity should ideallyintegrate multiple parameters rather than depend on asingle measurement. If multiple qualitative signs of MRare present, no further measurements are required. If there