DK2985_C000 1..28 - AlSharqia Echo Club

Mitral Valve Replacement and Repair 423(A)(B)diastoleVELOCITYPHTVmax1V T2 = 0.7 x VmPHT: 86.4 msTIMEFigure 18.8 (A) Measurement by continuous-wave Doppler of the pressure half-time (PHT) in a functional mitral bileaflet St. Judemechanical prosthesis. (B) The PHT corresponds to the time required for the pressure gradient to drop by half. The corresponding velocitiesare obtained through the simplified Bernoulli’s equation (V m , mean velocity; V max , maximal velocity; V T1/2 , velocity half-time).the periphery of the disk. Dysfunctional MR will be discussedin the following section.V. MULTIPLANE TEE EVALUATIONPreoperative and immediate postoperative (pre- and postcardiopulmonarybypass pump) evaluations should alwaysbe performed with a systematic approach (8). The echocardiographicexamination should include the evaluation ofother (native or prosthetic) valves as well as the evaluationof left ventricular size and global and regional function.Evaluation of prosthetic valve anatomy and functionshould include a full 2D imaging sweep, followed bycolor flow imaging and CW Doppler across the prosthesisand PW Doppler examination of the pulmonary veins.A. Two-Dimensional EvaluationTransesophageal echocardiography is the ideal tool forevaluating mitral prostheses. Two-dimensional evaluationinvolves real-time imaging in all imaging planes (0–1808)at the mid-eosophageal level. Rotation of the imagingangle at this level allows identification of the optimalimaging plane to observe the full motion of prostheticvalve occluders (leaflets, disks, or ball according totype). Machine settings should be adjusted to optimizethe image. The depth should be adjusted to maximizethe visualization of the prosthesis and the surroundingstructures. Keeping the prosthesis in the center of theimaging display, systematic slow sweeps from one sideof the sewing ring to the opposite in orthogonal viewsare important in picking up abnormal structures or flowsnot present in the middle of the prosthesis. The transgastricview must also be used to complete the evaluation of theventricular side of the prosthesis and permit visualizationand evaluation of the subvalvular apparatus and the LV,which is obscured by the prosthetic material at mid-esophageallevel.During 2D examination, a keen eye should look out forreduced occluder excursion, leaflet sticking, pannus, valverocking, abscess, foreign bodies such as thrombus orvegetation, and, particularly in the immediate postcardiopulmonarybypass (CPB) period, retained mitralvalvular apparatus that could impede the free movementof the mobile components of the prosthetic valve.During normal function, bileaflet mitral prosthesesopen and close symmetrically and generally in synchrony(Fig. 18.6). The puppet in the ball-in-cage prosthesisshould have full to-and-fro excursion within the cage(Fig. 18.10). The mobile components should not remainheld in either the open or closed position. However, asynchronousor incomplete movement of the occluder can beseen in the absence of prosthetic dysfunction in certaincases, for example, irregular heart rhythm (atrial fibrillation,multiple extrasystole, or ventricular pacing). In theimmediate/early post-CPB period, abnormal movementof the prosthesis occluder could be present and disappearjust a few minutes after reestablishing normal circulationand left ventricular function.The identification of abnormal movement of theprosthesis occluder in the early post-CPB period in theoperating room warrants immediate surgical reassessmentand correction that sometimes simply consists of rotatingthe prosthesis within the sewing ring or resecting some“excess” subvalvular tissue (Figs. 18.11 and 18.12). Thismay prevent a late second look which represents ahigh-risk early reoperation.