Abstract

Non invasive ultrasound heart and flow characterization has been widely applied to mammals but its application to other vertebrate groups is poorly explored. Ultrasonographic characterization of the marine turtle's heart and great vessels has been difficult to achieve because of morphological relation of the heart to other structures such as the plastron, omoplates and lungs. The objective of this work was to apply ultrasound technology to identify and characterize heart chambers and intracardiac flows of the marine turtle loggerhead sea turtle (Carreta carreta). Echocardiography was performed in seven non-anesthetized specimen using the Acuson Sequoia 512 ultrasound machine, and different frequency probes: 3, 8 and 15 MHz. The probes were applied over the plastron and "supraclavicular" fossae and oriented in order to obtain short and long-axis views of the heart chambers and outflow vessels. Ultrasound images were acquired and recorded as frames and clip sequences in Dicom format in hard disk of the ultrasound machine; all studies were also recorded on a video tape super VHS Sony tape recorder. Ultrasound images obtained allowed identification and characterization of heart ventricle, distinguishing the cavuns, both right and left atrium, valvular structures and outflow vessels--aortic and pulmonary arteries. Doppler flow 2D images and spectrum allowed to define flow direction and its relation to systole and diastole intervals. This new approach is applicable and sensitive to study morphology and cardiovascular physiology of the turtle heart. Studies in development deal with non invasive haemodynamic quantification of filling and ejection flow velocity and determination of functional indices such as cardiac output. The clarification of blood flow dynamics during cardiac cycle in relation with the respiratory frequency in turtles, and particularly the role of anatomical feature such as the partial septation in minimizing and controlling the intraventricular shunt, will help to improve the intervention on some of the human congenital anomalies called "univentricular heart" (two atria, but only 1 ventricle, with, often, the outlet to both systemic and pulmonary circuits via an accessory chamber).

Acknowledgements

This work was supported by: Zoomarine, UIC and CCMar (pluriannual funding from Fundação para a Ciência e Tecnologia).