Fig. 6.
Mitral valve (left ventricular) inflow profiles during active and hibernation periods, and two points of arousal in ground squirrels. (A) During the active period, early ventricular filling (E) and atrial contraction (A) flow profiles are identified in a typical relationship to each other. The aortic flow profile (Ao) is also seen. (B) Only two animals exhibited atrial contraction flow profiles during hibernation, of very low velocity. (C) During early arousal, atrial contraction profiles were frequently identified. (D) With increasing heart rate, atrial contraction flow became summated with the early filling flow, suggesting that early filling was not yet complete at the time of atrial contraction. Note: Ao flow profiles are not optimized in all images. Heart rate (fH) is in beats min−1.