This study aimed to determine standard left (LV) and right ventricular (RV) transesophageal echocardiographic (TEE) measurements in swine. Additionally, global myocardial work index (GWI) was estimated using pressure-strain loops (PSL). A comprehensive TEE examination was conducted in ten anesthetized, intubated and mechanically ventilated healthy female German landrace swine, weighing 44 to 57 kg. For GWI calculation, we performed LV and RV segmental strain analysis and used invasively measured LV and RV pressure to obtain PSL. The GWI and further myocardial work indices were calculated from the area of the PSL using commercially available software. Furthermore, hemodynamic measurements were obtained using indwelling catheters. We obtained complete standardized baseline values for left and right ventricular dimensions and function. Biplane LV ejection fraction was 63 ± 7 % and the LV end-diastolic volume was 70.5 ± 5.9 ml. Tissue Doppler estimated peak tricuspid annular systolic velocity was 13.1 ± 1.8 cm/s. The Doppler estimated LV and RV stroke volume index were 75.6 ± 7.2 ml/m2 and 76.7 ± 7.8 ml/m2 respectively. Pulsed wave Doppler derived cardiac output correlated well with cardiac output estimated using the thermodilution method (7.0 ± 1.2 l/min vs. 7.0 ± 1.1 l/min, r = 0.812, p = 0.004). The LV global longitudinal strain was -21.3 ± 3.9 % and the RV global longitudinal strain was -15.4 ± 2.5 %. LV GWI was 1885(1281–2121) mmHg*% and 297 ± 62 mmHg*% for the RV. LV global myocardial work efficiency was 82.6 ± 4 % and 83(72–88) % for the RV. TEE offers sufficient morphological, functional and hemodynamic assessment of the heart in swine. Myocardial contractility and mechanics can be reliably evaluated with the non-invasive GWI derived from echocardiography without additional invasive measures.
Background Coronary physiology assessment in rodents by ultrasound is an excellent noninvasive and easy to perform technique, including pulsed-wave Doppler (PWD) and myocardial contrast echocardiography (MCE). Both techniques and the corresponding calculated parameters were investigated in this study at rest as well as their response to pharmacologically induced stress. Methods Left ventricular myocardial function was assessed in eight anaesthetised rats using transthoracic echocardiography. Coronary physiology was assessed by both PWD of the left coronary artery and MCE using a bolus method. Measurements were performed at rest and under stimulation with adenosine and dobutamine. Effects of stimulation on the calculated parameters were evaluated and rated by effect size (η2). Results Changes could be demonstrated by selected parameters of PWD and MCE. The clearest effect in PWD was found for diastolic peak velocity (η2 = 0.58). It increased from 528 ± 110 mm/s (mean ± standard deviation) at rest to 839 ± 342 mm/s (p = 0.001) with adenosine and 1093 ± 302 mm/s with dobutamine (p = 0.001). The most distinct effect from MCE was found for the normalised wash-in rate (η2 = 0.58). It increased from 1.95 ± 0.35% at rest to 3.87 ± 0.85% with adenosine (p = 0.001) and 3.72 ± 1.03% with dobutamine (p = 0.001). Conclusion Induced changes in coronary physiology by adenosine and dobutamine could successfully be monitored using MCE and PWD in anaesthetised rats. Due to the low invasiveness of the measurements, this protocol could be used for longitudinal animal studies.
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