Fetal Echocardiographic Evaluation of the Bottlenose Dolphin (Tursiops truncatus)

Abstract

In humans, fetal echocardiography represents the most important tool for the assessment of the cardiovascular well-being of the fetus. However, because of logistic, anatomic, and behavioral challenges, detailed fetal echocardiographic evaluation of marine mammals has not been previously described. Because the application of fetal echocardiography to cetaceans could have both clinical and academic importance, an approach to evaluating the fetal dolphin's cardiovascular status was developed with conventional, fetal echocardiographic techniques developed in humans. Eight singleton fetal bottlenose dolphins (Tursiops truncatus) were evaluated, each between 6 and 11 mo gestation; six fetuses underwent two fetal echocardiographic evaluations each, four at 3-mo intervals, and two at 0.5-mo intervals. Evaluations were performed without sedation, using conventional, portable ultrasound systems. Multiple transducers, probes, and maternal dolphin positions were used to optimize image quality. Fetal echocardiography included two-dimensional imaging and color flow mapping of the heart and great arteries, as well as pulsed Doppler evaluation of the umbilical artery and vein. Thorough evaluations of the fetal dolphins' cardiovascular status were performed, with the greatest resolution between 8 and 9 mo gestation. With the use of published human fetal echocardiographic findings for comparison, fetal echocardiography demonstrated normal structure and function of the heart and great arteries, including the pulmonary veins, inferior vena cava, right and left atria, foramen ovale, tricuspid and mitral valves, right and left ventricles, ventricular septum, pulmonary and aortic valves, main pulmonary artery and ascending aorta, and ductus arteriosus. Pulsed Doppler techniques demonstrated normal umbilical arterial and venous waveforms, and color flow mapping demonstrated absence of significant valvar regurgitation. Fetal echocardiography, particularly between 8 and 9 mo gestation, can provide a safe and detailed assessment of the cardiovascular status of the fetal bottlenose dolphin.

Within-day and between-day variability of transthoracic anatomic M-mode echocardiography in the awake bottlenose dolphin (Tursiops truncatus)

“…Fetal echocardiography was recently described in BN by Sklansky et al 19 The authors reported that a detailed assessment of fetal BN cardiovascular status, including 2D imaging and color flow mapping of the heart and great arteries as well as pulsed Doppler evaluation of the umbilical artery and vein, could be obtained between 8 and 9 months of gestation. 19 Another study, performed by the same authors on 4 adult BN trained to hold their breath following forced exhalation, showed that the TEE technique yielded high-quality images of the entire heart (atrioventricular and arterial valves, interatrial and interventricular septa, left and right atrial cavities, left and right ventricles, ascending aorta and main pulmonary artery). 4 The latter report also demonstrated mild tricuspid regurgitation in all BN, and mild aortic regurgitation in one BN using color flow Doppler mode.…”

Pregnancy and Fetal Development: Cephalic Presentation and Other Descriptive Ultrasonographic Findings from Clinically Healthy Bottlenose Dolphins (Tursiops truncatus) under Human Care

“…Lacave showed how the diameters of the skull increase more slowly than the thoracic diameters, and that the thoracic diameters represent the limit of accuracy in late pregnancy [25]. Sklansky et al (2010) recognize the utility of fetal echocardiography as a safe technique able to evaluate the cardiovascular system in the bottlenose dolphin, especially in the period between the eighth and the ninth month of gestation. As in humans, this technique allows us to identify congenital cardiac anomalies [26][27][28] and to identify the possible causes of perinatal mortality risk associated with physiological abnormalities and cardiac hemodynamics [29,30].…”

“…Sklansky et al (2010) recognize the utility of fetal echocardiography as a safe technique able to evaluate the cardiovascular system in the bottlenose dolphin, especially in the period between the eighth and the ninth month of gestation. As in humans, this technique allows us to identify congenital cardiac anomalies [26][27][28] and to identify the possible causes of perinatal mortality risk associated with physiological abnormalities and cardiac hemodynamics [29,30]. In most cases, the optimal visualization of the fetal heart is obtained by positioning the pregnant female in lateral decubitus, homolaterally to the uterine horn in which the fetus is housed [26,27].…”

“…As in humans, this technique allows us to identify congenital cardiac anomalies [26][27][28] and to identify the possible causes of perinatal mortality risk associated with physiological abnormalities and cardiac hemodynamics [29,30]. In most cases, the optimal visualization of the fetal heart is obtained by positioning the pregnant female in lateral decubitus, homolaterally to the uterine horn in which the fetus is housed [26,27]. The optimal window is located near the maternal navel, proximal to the dorsal and caudal-ventral fin compared to the caudal fin.…”

Synopsis on the Most Common Pathologies of Dolphins

“…Using conventional, portable ultrasound systems without sedation (Sklansky et al, 2010) have implemented fetal echocardiography between 8-9 months gestation. They concluded that fetal echocardiography can provide a safe and detailed assessment of the cardiovascular status of the fetal bottlenose dolphin.…”