DK2985_C000 1..28 - AlSharqia Echo Club

Native Aortic Valve 353(A)(B)LARPALVAoRV(C)(D)LVLARPAPERVAoFigure 15.32 (A, B) Mid-esophageal long-axis view of the aortic valve at 988 in a patient with mild aortic regurgitation: the width ofthe regurgitant jet immediately below the aortic valve is less than one-third of the left ventricular outflow tract (LVOT) diameter indicatingmild aortic regurgitation. (C, D) Same view at 1128 in a different patient: the width of the regurgitant jet is as wide as the LVOTdiameter, consistent with severe aortic regurgitation. Note also the hemisphere of proximal isovelocity surface area (PISA) on the aorticside of the anatomic regurgitant orifice and the dilated ascending aorta (Ao) (LA, left atrium; LV, left ventricle; PE, pericardial effusion;RPA, right pulmonary artery; RV, right ventricle).PISAellipse and measuring the diameters of the mitral annulusin the four- and two-chamber midesophageal views (D 1and D 2 ). The product of mitral inflow VTI (cm) andmitral annular area (cm 2 ) yields the mitral diastolicstroke volume (cm 3 ).Area of ellipse ¼ p (D 1 D 2 )(15:12)4Alternatively, flow across any other competent valvecould also be used, although it is more difficult to alignthe Doppler ultrasound beam properly with the directionof tricuspid or pulmonic flow by TEE.Pitfalls of Regurgitant FractionThe measurement of regurgitant fraction is not usuallydone by anesthesiologists in the operating room because itis time-consuming and may distract from patient care andmonitoring. Moreover, the measurement of the SVacross the mitral and the AoV should be done under thesame hemodynamic conditions. Therefore, as thesemeasurements are obtained sequentially rather thansimultaneously, rapid transient changes occurring duringanesthesia and/or surgery may affect the validity of theobtained regurgitant fraction.Another important source of error originates from themeasurement of the mitral annulus and LVOT diameter.A small error in the measurement of these diameters ismagnified to its square value in the calculation of thecross sectional area for the measurement of the volumetricflow rate.Measurement of the aortic regurgitant volume is alsocritically influenced by the position of the samplevolume during PW Doppler examination. Doppler angulationexceeding 208 between the ultrasound beam and thedirection of flow will yield a value lower than the trueforward aortic SV, and consequently a lower aortic regurgitantvolume. Overestimation of the effective forward SVat the MV will also result in a smaller aortic regurgitantvolume. This may occur when the sample volume islocated at the tip of the mitral leaflets rather than at thelevel of the mitral annulus. Sampling below the mitralannulus may also result in contamination of the mitralinflow signal with the AR jet which would further