Echopac bt 11

The Doppler echo parameter 'pulmonary artery acceleration time' (PAAT) is negatively correlated with the mean pulmonary arterial pressure (PAP) measured invasively, namely increased pulmonary hypertension or an increase in PAP as judged by a decreased PAAT (28 (link),29 (link)). Therefore, PAAT is considered as an echocardiographic indicator of PH (30 (link)). PH was also assessed using Doppler echocardiography at day 28 of the study. Transthoracic closed-chest echocardiography was performed by an experienced doctor using a Vivid E9 ultrasound system equipped with a 12-MHz transducer (GE Healthcare). Rats were anesthetized by i.p. injection of 3% sodium pentobarbital (40 mg/kg) and placed in a shallow left lateral decubitus position, and an ultrasound gel was applied to the shaved chest. Blood flow through the pulmonary artery and PAAT were measured in the two-dimensional short-axis parasternal view by M-mode and Pulsed-wave Doppler at the level of the pulmonary valve. Papillary muscles were used as the reference point for echocardiography measurements. PAAT was measured from the onset of systolic flow to peak pulmonary outflow velocity according to the American Society of Echocardiography guidelines (31 (link)). The acquisition of Echo images and all the echocardiographic analyses were performed using Echopac BT11 software (v.6.5; GE Healthcare).

The evaluation of the echocardiograms was accomplished by means of a Vivid 7 (General Electric, Horten, Norway) echocardiographic machinery. A frame rate of 60 - 75/s was used for acquiring the images. Then, they were digitally transferred to a remote workstation for offline analysis (Echopac BT 11.1.0, General Electric, Horten, Norway). All analyses were performed by only one experienced operator who had been kept blinded to clinical and biochemical data concerning both the patients, i.e. subjects taking sacubitril/valsartan, and controls. Two-dimensional speckle tracking echocardiography was carried out using a semiautomatic algorithm.
In brief, using manual determination, three reference points (two annular and one apical) were chosen in each of the three apical views, so as to enable the software to monitor the myocardium in a semi-automated manner during the entire course of the cardiac cycle. Each ventricular wall was then splitted into three segments so as to achieve the generation of 17 segments encompassing the entire myocardium. Thorough manual inspection for tracking purposes was carried out, and in the case of imperfect tracking, the segment was removed from the analysis. Longitudinal strain curves were built for each segment and the maximum value was calculated. The GLS was then inferred as the mean of all 17 segments.