RESUMO
Background: Novel ultrasound technology and software processing allow offline evaluation of tricuspid annular plane systolic excursion and mitral annular plane systolic excursion measurements. We wished to compare both novel 4D matrix (eM6C) and conventional (RAB6-D) transducers with variable settings (electronic spatiotemporal image correlation, spatiotemporal image correlation and four-dimensional real time) to determine if there was a significant difference in absolute value, quality and repeatability of the resultant reconstructed image and M-mode trace. Methods: A blinded prospective cross-sectional study of normal fetuses from 23 to 38 weeks' gestation were recruited. After routine sonography, four-dimensional volumes were stored and analysed using GE 4DView™ software. Statistical analysis explored variability, correlations and repeatability of the measurements with chi-square analysis, intraclass correlations and the Bland-Altman comparison plots. A scoring system was devised for image quality. Results: Eighteen participants generated 282 data volumes. Absolute values demonstrated some inconsistencies for both tricuspid annular plane systolic excursion and mitral annular plane systolic excursion measurements with variations between transducers: the highest for the RAB6-D/spatiotemporal image correlation setting and the lowest for the four-dimensional real-time settings. The RAB6-D/spatiotemporal image correlation setting was the most repeatable combination (intraclass correlation coefficient = 0.85). Poorest image quality (M-mode trace, four-chamber view, annuli) came from the RAB6-D/four-dimensional real-time combination with the eM6C/electronic spatiotemporal image correlation and RAB6-D/spatiotemporal image correlation settings being nearly identical. Conclusion: We show that transducer and setting combinations influence absolute tricuspid annular plane systolic excursion/mitral annular plane systolic excursion measurements, so need to be articulated in future research. The transducer setting (electronic spatiotemporal image correlation/spatiotemporal image correlation/four-dimensional real time) was a more significant factor than the type of transducer (conventional vs matrix). Subjective image evaluation does not correlate well with repeatability of image acquisition. Further studies are needed to compare measurements using four-dimensional post-processing tools against conventional real-time measurements.
RESUMO
AIM: Longitudinal ventricular contraction is a parameter of cardiac performance with predictive power. Right ventricular (RV) longitudinal function is impaired in patients with free pulmonary regurgitation (PR) following corrective surgery for Tetralogy of Fallot (TOF). It remains unclear whether this is a consequence of the surgical repair, or whether it is inherent to PR. The aim of this study was to assess the relationship between longitudinal, lateral and septal pumping in a porcine model of isolated PR. METHODS: Piglets were divided into a control (n = 8) group and a treatment (n = 12) group, which received a stent in the pulmonary valve orifice, inducing PR. After 2-3 months, animals were subjected to cardiac magnetic resonance imaging. A subset of animals (n = 6) then underwent percutaneous pulmonary valve replacement (PPVR) with follow-up 1 month later. Longitudinal, lateral and septal contributions to stroke volume (SV) were quantified by measuring volumetric displacements from end-diastole to end-systole in the cardiac short axis and long axis. RESULTS: PR resulted in a lower longitudinal contribution to RV stroke volume, compared to controls (60.0 ± 2.6% vs. 73.6 ± 3.8%; P = 0.012). Furthermore, a compensatory increase in septal contribution to RVSV was observed (11.0 ± 1.6% vs. -3.1 ± 1.5%; P < 0.0001). The left ventricle (LV) showed counter-regulation with an increased longitudinal LVSV. Changes in RV longitudinal function were reversed by PPVR. CONCLUSION: These findings suggest that PR contributes to decreased RV longitudinal function in the absence of scarring from cardiac surgery. Measurement of longitudinal RVSV may aid risk stratification and timing for interventional correction of PR in TOF patients.