Sex Differences in Hemodynamics at Rest and During Dynamic Exercise in Healthy Older Adults

• Main Author: Esfandiari, Sam
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2019
• Subjects: Physiology
• ISBN: 9781392428498; 1392428491

Sex differences in the left ventricular (LV) chamber structure and function may predispose women to elevated LV and left atrial (LA) filling pressures during exercise. Heart failure with preserved ejection fraction and pulmonary hypertension are conditions that demonstrate a clear predilection among women. This thesis aimed to examine sex differences in pulmonary and systemic hemodynamics at rest and during exercise in healthy older adults. Healthy men and women ≥ 45 years old were recruited. Pulmonary artery wedge pressure (PAWP) and cardiac output were measured using right heart catheterization. LA volumes were measured using echocardiography. Participants were studied at rest and during two consecutive stages of Light and Moderate intensity cycle ergometry exercise. Chapter 4 demonstrated that although the rise in the PAWP response to submaximal exercise appears similar in men and women, the increase in PAWP occurs despite lower work rate in healthy older women, even when adjusted for smaller body size. In Chapter 5, systematic review of the literature showed that in healthy individuals, normal mean PAWP at rest is 8 mmHg at rest, increasing during exercise reaching in excess of 20 mmHg in some adults > 40 years even at Light intensity. Chapter 6 demonstrated that although the inter-relationships between PAWP, pulmonary vascular resistance and pulmonary vascular compliance are similar at rest and with exercise between men and women, at rest, pulmonary and systemic vascular compliance at rest are lower in healthy, middle-aged women compared to men. Further, the pulmonary effective arterial elastance, as a lumped parameter of RV afterload, is also higher amongst women. Finally, in Chapter 7, the LA pressure-volume loop at rest in healthy older men and women was constructed from analyses of timed pressure measurements and volume estimates. Despite subtle qualitative differences in this relationship, the operating compliance of the LA was similar between men and women. This work provides evidence for sex differences in the pulmonary and systematic hemodynamics at rest and in response to submaximal exercise, and contributes sex-specific data from which reference ranges, representative of untrained healthy older adults, may be developed.