The feasibility of measurement of different right ventricular systolic function parameters by intraoperative trans-esophageal echocardiography and their interchangeability with transthoracic echocardiography in pediatric patients undergoing cardiac surgery- interim results from an ongoing study

Abstract

Introduction All the parameters recommended for functional assessment of right ventricle (RV) in children are based on transthoracic echocardiographic (TTE) measurements¹. Intraoperative echocardiography during pediatric cardiac surgery is, however, mainly dependent on trans-esophageal echocardiography (TEE). We planned to determine the feasibility of measurement of different RV systolic function parameters by intraoperative TEE and their interchangeability with TTE in pediatric patients undergoing cardiac surgery. Methods This ongoing single-centre, observational study has been registered (CTRI/2019/06/019743) after Institutional Ethics Committee clearance. After written, informed, parental consent, pediatric patients (1-18 years) undergoing corrective surgery for congenital heart diseases- are included. TEE transducer is inserted after induction of general anaesthesia. TTE examination is performed using Apical four-chamber (A4C) view. TEE examination is performed within 10 minutes of performing TTE, while keeping heart rate, mean arterial pressure and central venous pressure within 10% of that during performing TTE. Mid-esophageal four-chamber RV-focused (ME4C) view, Mid-esophageal modified bicaval view (MBC), Transgastric RV inflow view (TGRVI), Deep transgastric RV view (DTG-RV)- are used. All the recorded images/clips are analysed offline later, using Echopac-113 (GE) software. Fractional Area Change (FAC), Tricuspid annular plane systolic excursion (TAPSE), Tricuspid annular systolic velocity by pulsed-wave tissue Doppler (RV S’), Right ventricular index of myocardial performance (RIMP) (by tissue Doppler), Right ventricular free wall strain (RVFWS)- are measured. Feasibility is assessed as ability to acquire an image/loop deemed readable during the examination. Readable image/loop is defined as ability to completely delineate the endocardial border of the RV and tricuspid annulus in 2D-mode, to obtain completely traceable lines in M-mode (MM) and Angled M- mode (AMM), to obtain optimally aligned and completely traceable envelopes of pulsed wave Tissue-Doppler velocities. Agreement between TTE and TEE measured parameters are assessed by Bland-and-Altmann analysis. Results 42 patients has been recruited and analysed so far. The Mean±SD age of the patients was 6.5±4.6 years. Feasibility of measuring all the studied parameters was > 85% in all the TEE views (Table 1). There was good Intra- and Inter-observer reliability (Intra-class Correlation Coefficient > 0.8) of measurements of all the parameters in all the views (Both TTE and TEE) utilised. In comparison to TTE measurements, there were low bias in TEE measured parameters in: AMM measured TAPSE in ME4C and MBC views, FAC in ME4C view, RIMP in DTG-RV and TGRVI views, RVFWS in all the utilised views (Table 1). The limits of agreements, however, were wide (Table 1). Discussion Despite high feasibility, wide limits of agreement prevents intraoperative TEE measured RV function parameters to be used interchangeably with those measured by TTE for individual pediatric cardiac surgical patients.