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Objectives: Macaques are used in cardiovascular and metabolic research. We determined echocardiographic-derived reference values of left ventricular (LV) systolic and diastolic function in healthy adult bonnet macaques (Macaca radiata). Methods: Transthoracic echocardiography was performed during ketamine sedation in 83 (67% female) healthy monkeys (age 7–26 years). Results: Technically adequate studies were obtained in all subjects and required 10.1 ± 1.3 min of scanning time. Age correlated inversely with the following Doppler indices: E (r = –0.44, p < 0.001), E/A (r = –0.26, p = 0.02), E′ (r = –0.45, p < 0.001, E′/A′ (r = –0.44, p < 0.001), E/E′ (r –0.25, p = 0.03), S′ (r = –0.33, p = 0.003), Vp (r = –0.26, p = 0.049). LV mass was more strongly correlated with crown rump length (r = 0.72, p < 0.001) and body surface area (r = 0.70, p < 0.001) than with body mass index (r = 0.47, p < 0.001) and weight (r = 0.63, p < 0.001). Conclusions: This study demonstrates echocardiography is feasible for characterizing LV function. Age-related changes in Doppler indices in primates are similar to those in humans. LV mass is more closely related to fat-free mass indices. We provide reference values for LV systolic and diastolic function in adult bonnet macaques across the captive life span.

Swimming/hydrotherapy produces hemodynamic and physiological changes related to water immersion (WI). To evaluate the effects of head out (HO) WI on central hemodynamics, we prospectively studied 21 healthy subjects (62% male, age 37 +/- 13 years). Central aortic blood pressures (CA-BPs) and reflected wave properties were evaluated using applanation tonometry at baseline and upon 2 minutes of waist (W) and mid-chest (C) HOWI. Heart rate (HR) decreased from 83 +/- 15 to 73 +/-10 beats/min (P.001). Brachial artery pulse pressure (PP) was unchanged (45 +/- 11 to 46 +/- 7 mm Hg; P = .20), CA-PP increased stepwise (27 +/- 7 to 32 +/- 8 to 33 +/- 6 mm Hg; P.001). Reflected wave amplitude (P(s) - P(i)), and HR-corrected augmentation index (AI(a)@75) increased stepwise from baseline-W-C level HOWI [(P(s) - P(i)): 2 +/- 3 to 7 +/- 4 mm Hg, P.001; AI(a)@75: 8 +/- 11 to 19 +/- 10%; P.001]. HR-corrected ejection duration (ED(c)) and reflected wave systolic duration (Deltat(r)) increased progressively (ED(c): 389 +/- 23 to 408 +/- 25 to 435 +/- 13 milliseconds; P.001; Deltat(r): 106 +/- 32 to 165 +/- 21 ms; P.001). Indices of left ventricular (LV) workload including wasted LV energy subendocardial viability and tension time index increased upon HOWI. HOWI increases the amplitude and the duration of the reflected aortic pressure wave, increases wasted LV pressure energy, workload, and oxygen demand.