Perinatal cardiovascular evaluation in dorper sheep echocardiographic description and behavior of the heart rate variability on the field

Abstract

The heart is innervated by the autonomic nervous system, with a predominance of sympathetic and parasympathetic activity associated, respectively, with increases and decreases in the heart rate, as illustrated by the Heart Rate Variability (HRV). Pregnancy induces significant changes in the maternal cardiovascular and hemodynamic systems. This study aimed at evaluating changes in the clinical and echocardiographic parameters of pregnant sheep, as well as the HRV indexes due to the physiological alterations that happen at this stage implicating in high maternal metabolic demands. For this purpose, the study evaluated 10 Dorper sheep through their pregnancy, starting from the second month until the day after delivery (24 h after birth), being evaluated clinical parameters, some of the echocardiographic measurements and electrocardiographic examinations focused on the HRV. The HRV indexes were obtained through the Televet 100® system. There were increases in the thickness of the interventricular septum during diastole starting from the third month and in the internal diameter of the left ventricle during systole and diastole at the second and third months, that diverged across the moments studied, while the ejection fraction increased as the pregnancy progressed. There were increases in the LVFWs values in the 2nd and 5th months. The size of the left atrium increased starting at the second month. The SDNN, RMSSD and PNN 50 HRV indexes were higher at the fifth month of pregnancy and after delivery. There were no significant differences in the frequency-domain HRV indexes during pregnancy. As pregnancy progresses, there is an increase in some echocardiographic parameters as well as a predominance of parasympathetic autonomic nervous system activity. The gestation leads to alterations in the clinical parameters and the activity of the autonomic nervous system.