Christian Rosendal

Left Ventricular Outflow Tract: Intraoperative Measurement and Changes Caused by Mitral Valve Surgery

BACKGROUND The impact of mitral valve surgery on left ventricular outflow tract (LVOT) dimensions is unclear. Real-time three-dimensional transesophageal echocardiography permits excellent visualization of the LVOT and might improve standard two-dimensional measurements. In this study, LVOT area and shape were assessed before and after mitral valve surgery. METHODS Thirty-five patients undergoing mitral valve repair or replacement were retrospectively included in the study and compared with 15 patients undergoing coronary artery bypass grafting. LVOT area was measured by planimetry. Maximum possible methodologic errors by assuming a circular LVOT and an eccentricity index were calculated. LVOT diameter in a midesophageal long-axis view served to calculate the error for the circular LVOT determined in common intraoperative practice. RESULTS Common intraoperative two-dimensional measurements underestimated actual LVOT area by 21%. Mitral valve surgery led to a significant reduction of LVOT area by 7%. Although LVOT height remained unchanged, width decreased from 2.72 to 2.53 cm (-7%), resulting in a more circular shape of the LVOT. This effect was more pronounced the smaller the size of the implanted annuloplasty ring or prosthesis. Coronary artery bypass grafting did not affect the LVOT. Left ventricular ejection fraction was significantly correlated with LVOT eccentricity. Impaired ventricular function and higher end-systolic volumes were associated with a rounder shape. CONCLUSIONS The eccentric LVOT shape leads to a distinct underestimation of its area with two-dimensional measurements. LVOT eccentricity is less distinct in patients with low ejection fractions and higher end-systolic volumes. LVOT width is decreased through annuloplasty rings and prostheses, and the smaller the implanted device, the more profound the reduction.

Right ventricular function during orthotopic liver transplantation: Three-dimensional transesophageal echocardiography and thermodilution

BACKGROUND Right ventricular (RV) function is an important aspect of anesthesia management during orthotopic liver transplantation (OLT). Because of its geometrical complexity, assessment of RV dimensions with transesophageal echocardiography (TEE) is a difficult task. The aim of this prospective single-site study was to investigate the feasibility of intraoperative assessment of RV parameters based on reconstructive three-dimensional (3D) TEE and to compare the measurements to thermodilution-derived values acquired with a modified pulmonary artery catheter. MATERIAL/METHODS Measurements were performed at four different time points during 30 OLT with 3D-TEE. At the same time comparative values of RV parameters were acquired with a fast-response thermistor pulmonary artery catheter. RESULTS 3D reconstruction was feasible in all patients. RV dimensions measured with 3D-TEE averaged 119.4 ml (± 38.5 ml) for enddiastolic and 68.9 ml (± 27.7 ml) for endsystolic volumes. The RV ejection fraction was 42.2% (± 9.3%). The volumes obtained by thermodilution were 263.7 ml (± 64.5 ml) enddiastolic and 159.3 ml (± 47.5 ml) endsystolic, both significantly greater than by 3D-TEE, and the ejection fraction was found to be 39.5% (± 8.4%). No correlation was found between the volumes or the function determined by either method. CONCLUSIONS Reconstructive 3D-TEE is a viable technique during OLT and leads to plausible RV parameters. However, no correlation was found with simultaneous measurements or parameters performed with thermodilution. However, based on our data cardiac output measurements by thermodilution appear reasonable. Due to both lack of agreement with 3D-TEE and extraordinary high RV volumes the question about the most valuable monitoring technique of RV dimensions and function during OLT can not finally be answered.

Comparison of Intraoperative Three-Dimensional Doppler Color Flow Mapping to Assess Mitral Regurgitation

Background: Three‐dimensional (3D) transesophageal echocardiography (TEE) enables the determination of the vena contracta area (VCA), which is an approved parameter to quantify mitral regurgitation (MR). The aim of this study was to determine the VCA in the operative setting and to compare it to alternative 3D and standard 2D methods, with respect to different etiologies of MR. Methods: MR in 56 consecutive patients undergoing cardiac surgery was evaluated using 2D and 3D TEE. VCA, vena contracta (VC), and effective regurgitation orifice area (EROA) by 3D and 2D flow convergence methods were determined. The correlations among the methods and the determined areas were evaluated. Results: EROA determination using 3D flow convergence areas correlated strongly with VCA (r = 0.653), however the resulting areas were considerably smaller. VC measurements in the 3D data set correlated slightly less (r = 0.629). EROA, which was determined using 2D flow convergence areas, showed the strongest correlation among the 2D methods (r = 0.406). 2D VC measurements showed weak to no correlation with VCA. Although a correlation was detected when using the biplane method or the midesophageal long‐axis view to measure VC, statistical significance was only reached in functional MR and MR due to simple prolapse. Conclusions: Intraoperative 3D methods to determine MR were feasible and showed improved correlation with VCA compared to 2D measurements. The agreement of 2D methods with VCA declined from functional MR to MR due to prolapse. We recommend the utilization of 3D color Doppler for intraoperative evaluation of MR, especially in patients with complex mitral valve prolapses.

Image Quality Influences the Assessment of Left Ventricular Function An Intraoperative Comparison of Five 2-Dimensional Echocardiographic Methods With Real-time 3-Dimensional Echocardiography as a Reference

Transesophageal echocardiography has become a standard tool for eval uating left ventricular function during cardiac surgery. However, the image quality varies widely between patients and examinations. The aim of this study was to investigate the influence of the image quality on 5 commonly used 2‐dimensional methods.