Why the study?
Giraffe cardiovascular function appears unimpacted by marked left ventricular thickening, leading researchers to assess whether physiologically adapted atrioventricular conduction optimizes atrial and ventricular contractions.
Do giraffes exhibit physiologically adapted atrioventricular conduction compared to allometric scaling predictions?
Do giraffes exhibit physiologically adapted atrioventricular conduction compared to allometric scaling predictions?
Giraffes exhibit species-specific atrioventricular adaptations, including longer PR intervals and slow ventricular response during atrial fibrillation, likely to optimize cardiac function despite extreme morphological adaptations.
Adapted AV conduction may preserve function despite giraffe LV thickening; leaves open relevance to human cardiomyopathy.
Unique cardiovascular adaptations in giraffes ( Giraffa Camelopardalis reticulata ) have been the focus of numerous investigations for almost a century. The vertical distance between the heart and brain impose high pressure on the giraffe left ventricle leading to thickening that exceeds heart in other mammals. Yet, cardiovascular function appears to be unimpacted by these morphologic differences. Physiologically adapted atrioventricular conduction may contribute to these unique cardiovascular characteristics. Atrioventricular (AV) function was assessed to determine whether physiologically adapted AV intervals might optimize the delay between atrial and ventricular contractions. Using ambulatory and intracardiac recordings, we report a longer PR interval in giraffes than predicted by allometric scaling. Slow ventricular response during atrial fibrillation further supports species-specific atrioventricular adaptations.
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Shivkumar et al. (2021) studied this question.
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