Feasibility and reference intervals assessed by conventional and speckle‐tracking echocardiography in normal hamsters

Abstract

Objectives This study aimed to determine feasibility, reference intervals, and reproducibility of left ventricular ejection fraction (LVEF) and speckle‐tracking echocardiography (STE) in adult Syrian hamsters. Background Syrian hamster is an experimental model for several heart diseases. Echocardiography allows the evaluation of structure and function with bidimensional conventional techniques and STE. However, there is no data regarding reference values for bidimensional LVEF and myocardial strain in hamsters. Methods A total of 135 female Syrian hamsters were anesthetized and studied with a small animal dedicated echocardiography system. Echocardiography measurements were obtained from M‐mode and B‐mode images. Feasibility and 95% reference intervals were obtained for LVEF using three different approaches: LVEF_Teichholz (from M‐mode linear measurements), LVEF_BMode (from area‐length method), and LVEF_ STE (from strain), and for global longitudinal (GLS), circumferential (GCS), and radial (GRS) endocardial strain. Reproducibility was assessed as intra‐class correlation coefficients. Results Feasibility of LVEF and endocardial strain was high (95% in FEVE_Teichholz, 93% in the LVEF_BMode, 84% in the LVEF_STE, 84% from PSLAX, and 80% from PSSAX). Values of LVEF_Teichholz were significantly higher than values of LVEF_BMode, and LVEF_STE‐derived methods (59.0 ± 5.8, 53.8 ± 4.7, 46.3 ± 5.7, p < 0.0001). The 95% reference intervals for GLS, GCS, and GRS were respectively −13.6(−7.5;‐20.4)%, −20.5 ± 3.1%, and + 34,7 ± 7.0%. Intra‐class correlation coefficients were 0.49 – 0.91 for LVEF measurements, 0.73 – 0.92 for STE, with better results for LVEF_Teichholz and GLS. Conclusions Evaluation of LVEF by several methods and STE parameters is feasible in hamsters. Reference intervals for LVEF and STE obtained for this experimental animal model can be applied at future research.

Prospective study of ventricular function and myocardial deformation related to survival in acute Chagas disease: an experimental animal model

“…The influence of the heart rate in the echocardiographic analysis of myocardium deformation parameters is always a technical concern. We have previously published data showing little influence of the heart rate in the longitudinal myocardial deformation analysis in normal Hamsters, using the same equipment 20 . Although animals were not infected in the previous publication, the heart rate range was 204 ± 24 bpm, and it was even superior in comparison with the T. cruzi -infected group of the present study.…”

“…The end-diastole was automatically defined at the peak of the QRS complex. The end-systolic time was defined as the point of the smallest dimension of the LV cavity and visually checked by using the position of mitral leaflets in the background image in M20-mode 20 .…”

“…Echocardiography is an accurate and non-invasive tool for the investigation of Chagas cardiomyopathy, assessing left ventricle (LV) geometry and function through the evolution of CD 16 . New developments such as dedicated small animal equipment and high-resolution transducers 17 , in addition to new techniques like Speckle Tracking Echocardiography (STE), have enhanced the ability to study early myocardial damage in CD 18 - 20 .…”

Prospective analysis of myocardial strain through the evolution of Chagas disease in the hamster animal model

“…Definitions about what strain peak was measured were not always clarified in previous studies using STE in CD [ 25 , 26 ]. Normal values of deformation parameters of LV in Syrian hamsters were previously published by our research group [ 50 ]. In pathologies such as CCC, several LV conduction disturbances may be present and hence some LV segments can show post systolic peak deformations, which may not accurately represent patients’ myocardial systolic function [ 23 ].…”