Determination of Mitral Valve Area After Mitral Valve Repair Surgery for Mitral Stenosis Using 3-dimensional Transesophageal Echocardiography

After obtaining permission of the Institutional Review Board of Konkuk University Medical Center, Seoul, South Korea , patients scheduled to undergo elective MVP due to more than moderate MS and left atrial enlargement with or without atrial fibrillation (AFib) signed written informed consent agreements and prospectively participate in the present study.

In addition to the routine transthoracic echocardiographic evaluation, cardiac CT examination is performed in all recruited patients prior to surgery to determine MVA.

Induction of anesthesia and tracheal intubation are performed after the administration of intravenous etomidate 0.1-0.2 mg/kg and rocuronium 0.9 mg/kg followed by continuous infusion of remifentanil (0.5-1.0 mcg/kg/min). After tracheal intubation, sevoflurane (1.0 inspired vol%) and infusion of rocuronium (0.2 mg/kg/hr) are administered for anesthesia maintenance.

After anesthesia induction, pulmonary artery catheter (PAC) is placed in right internal jugular vein into pulmonary artery by pressure guidance and a 3D TEE probe (X-9™, Philips Medical Systems Andover, MA, USA) is inserted for the comprehensive intraoperative TEE examination using a 3D echocardiographic imaging platform (iE33; Philips Medical Systems, Andover, MA, USA). While momentarily turning off the ventilator, three consecutive velocity-time integrals (VTIs) of mitral inflow Doppler scans were obtained by applying the continuous wave Doppler parallel to the mitral inflow Color Doppler signal in the midesophageal long-axis view. In case of AFib, the biggest VTI among the 5 consecutive VTIs of the mitral inflow Doppler was used for determining PHT to detect maximal mitral inflow among irregular heartbeats. Immediately after recording the VTIs, a live 3D zoom "en face" MV view from the left atrium (LA) or left ventricle (LV) perspective is acquired.

As baseline data, MVA is determined by using PHT method (MVA-PHT): PHT of the mitral inflow deceleration slope is determined using stored mitral inflow Doppler VTI and the MVA are automatically calculated assuming MVA = 220/PHT. At the same time, a 2D image of the smallest MVA perpendicular to the mitral inflow at the maximal MV opening was achieved by post-processing including aligning and cropping of the acquired 3D images with an installed software (3DQ™ in Q-lab™, Philips, USA). MVA was determined by circumferential tracing of the leaflet edges of the MV opening in the cropped and reconstructed tomographic image from stored 3D volume image (MVA-3D) (Fig. 1). All MVA measurements were repeated 3 times within a minimal time interval by the same expert cardiac anesthesiologists with the mean value used for analysis.