Doppler echocardiography in a healthy, non-sedated Southern Sea Lion (Otaria flavescens) - a preliminary approach about the feasibility and clinical utility

Dassis, Mariela; León, Alberto Ponce de; Faiella, Adrián; Olguin, Javier; Saubidet, Alejandro; Rodríguez, Diego H.; Castro, Eduardo; Díaz, Alejandro

doi:10.1007/s11259-022-10019-4

Cited by 1 publication

(1 citation statement)

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“…The SVs and BWs of the adult sea lions in our study were similar to bottlenose dolphins (104-177 mL; 143-212 kg) (Miedler et al, 2015), and those of the fur seals in our study were similar to harbor seals (Phoca vitulina; 31.2-100.2 mL; 15-40 kg) (Kjekshus et al, 1982;Murdaugh et al, 1966;Ponganis et al, 1990). Interestingly, the 4-year-old Steller sea lion in our study had a lower SV (131.0 mL vs. 147.00 mL), but weighed more (139 vs. 107 kg) than an awake southern sea lion (Díaz et al, 2023). This difference may reflect our use of anesthesia or could indicate species-specific or age-related variation in SV.…”

Section: Northern Fur Seal and Steller Sea Lion Aorta Anatomysupporting

confidence: 71%

Ultrasound images of the ascending aorta of anesthetized northern fur seals and Steller sea lions confirm that the aortic bulb maintains continuous blood flow

Storlund,

Rosen,

Haulena

et al. 2024

J Exp Zool Pt A

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The increased size and enhanced compliance of the aortic bulb—the enlargement of the ascending aorta—are believed to maintain blood flow in pinnipeds during extended periods of diastole induced by diving bradycardia. The aortic bulb has been described ex vivo in several species of pinnipeds, but in vivo measurements are needed to investigate the relationship between structure and function. We obtained ultrasound images using electrocardiogram‐gated transesophageal echocardiography during anesthesia and after atropine administration to assess the relationship between aortic bulb anatomy and cardiac function (heart rate, stroke volume, cardiac output) in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopias jubatus). We observed that the aortic bulb in northern fur seals and Steller sea lions expands during systole and recoils over the entire diastolic period indicating that blood flow is maintained throughout the entire cardiac cycle as expected. The stroke volumes we measured in the fur seals and sea lions fit the values predicted based on body size in mammals and did not change with increased heart rates, suggesting that greater stroke volumes are not needed for aortic bulb function. Overall, our results suggest that peripheral vasoconstriction during diving is sufficient to modulate the volume of blood in the aortic bulb to ensure that flow lasts over the entire diastolic period. These results indicate that the shift of blood into the aortic bulb of pinnipeds is a fundamental mechanism caused by vasoconstriction while diving, highlighting the importance of this unique anatomical adaptation.

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