Aortic reservoir function of Japanese female pearl divers

Female pearl divers in Japan, called “ Ama,” engage in repeated breath-hold free-diving maneuvers for collecting pearls, seaweeds, and shellfish in the cold sea. We previously reported that they have lower systemic arterial stiffness than age-matched sedentary peers. As a follow-up study, we evaluated their segmental arterial stiffness and aortic reservoir function. A total of 120 non-medicated women living in the same fishing villages (mean age: 65 ± 11 yr), including 88 Ama and 32 age-matched sedentary peers, were studied. Pulse wave velocity from the heart to the brachial artery (hbPWV; partly reflecting proximal aortic stiffness) and between the brachial artery and the ankle (baPWV; reflecting stiffness of abdominal aorta and leg arteries) were measured. Aortic hemodynamic variables were estimated from applanation tonometry carotid arterial pressure waveforms via general transfer function. Carotid artery impedance was calculated from blood flow velocity and blood pressure of contralateral common carotid arteries. baPWV was not different between the groups ( P = 0.117), whereas hbPWV was significantly lower in pearl divers than sedentary peers ( P = 0.004). Additionally, Ama had significantly lower aortic reservoir pressure integral ( P = 0.029) and carotid artery impedance modulus in frequency ranges from 0.78 to 4.0 Hz ( P = 0.011~0.019) than in sedentary peers. Collectively, these findings indicate that lifelong female pearl divers have superior reservoir function in central elastic arteries (e.g., the proximal aorta and carotid artery) in comparison with age-matched sedentary women living in the same fishing village. NEW & NOTEWORTHY We previously reported that lifelong female pearl divers in Japan, called “ Ama,” have lower systemic arterial stiffness than age-matched sedentary peers. As a follow-up study, we evaluated their segmental arterial stiffness and aortic reservoir function. In comparison with age-matched sedentary women living in the same fishing village, Ama demonstrated significantly lower arterial stiffness in more proximal and elastic arterial segments and superior reservoir function in central elastic arteries.

Associations and clinical relevance of aortic-brachial artery stiffness mismatch, aortic reservoir function, and central pressure augmentation

Central augmentation pressure (AP) and index (AIx) predict cardiovascular events and mortality, but underlying physiological mechanisms remain disputed. While traditionally believed to relate to wave reflections arising from proximal arterial impedance (and stiffness) mismatching, recent evidence suggests aortic reservoir function may be a more dominant contributor to AP and AIx. Our aim was therefore to determine relationships among aortic-brachial stiffness mismatching, AP, AIx, aortic reservoir function, and end-organ disease. Aortic (aPWV) and brachial (bPWV) pulse wave velocity were measured in 359 individuals (aged 61 ± 9, 49% male). Central AP, AIx, and aortic reservoir indexes were derived from radial tonometry. Participants were stratified by positive (bPWV > aPWV), negligible (bPWV ≈ aPWV), or negative stiffness mismatch (bPWV < aPWV). Left-ventricular mass index (LVMI) was measured by two-dimensional-echocardiography. Central AP and AIx were higher with negative stiffness mismatch vs. negligible or positive stiffness mismatch (11 ± 6 vs. 10 ± 6 vs. 8 ± 6 mmHg, P < 0.001 and 24 ± 10 vs. 24 ± 11 vs. 21 ± 13%, P = 0.042). Stiffness mismatch (bPWV-aPWV) was negatively associated with AP ( r = −0.18, P = 0.001) but not AIx ( r = −0.06, P = 0.27). Aortic reservoir pressure strongly correlated to AP ( r = 0.81, P < 0.001) and AIx ( r = 0.62, P < 0.001) independent of age, sex, heart rate, mean arterial pressure, and height (standardized β = 0.61 and 0.12, P ≤ 0.001). Aortic reservoir pressure independently predicted abnormal LVMI (β = 0.13, P = 0.024). Positive aortic-brachial stiffness mismatch does not result in higher AP or AIx. Aortic reservoir function, rather than discrete wave reflection from proximal arterial stiffness mismatching, provides a better model description of AP and AIx and also has clinical relevance as evidenced by an independent association of aortic reservoir pressure with LVMI.