Alterations of pulmonary vascular afterload in exercise‐induced pre‐ and post‐capillary pulmonary hypertension

• Published in: Physiological reports Vol. 11; no. 1; pp. e15559 - n/a
• Main Authors: Karvasarski, Elizabeth, Bentley, Robert F., Buchan, Tayler A., Valle, Felipe H., Wright, Stephen P., Chang, Isaac S., Granton, John T., Mak, Susanna
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.01.2023; John Wiley and Sons Inc; Wiley
• Subjects: Blood pressure; Body mass index; Capillaries; Cardiac catheterization; Dyspnea; exercise; Heart; Hemodynamics; Humans; Hypertension; Hypertension, Pulmonary; Intubation; Original; Physiology; Pulmonary arteries; Pulmonary artery; Pulmonary hypertension; Pulmonary Wedge Pressure; resistance‐compliance time; Variables; Variance analysis; Vascular Resistance; Veins & arteries; exercise; resistance-compliance time; pulmonary hypertension; hemodynamics
• ISSN: 2051-817X
• DOI: 10.14814/phy2.15559

Exercise imposes increased pulmonary vascular afterload based on rises in pulmonary artery (PA) wedge pressure, declines in PA compliance, and resistance‐compliance time. In health, afterload stress stabilizes during steady‐state exercise. Our objective was to examine alterations of these exercise‐associated stresses in states of pre‐ and post‐capillary pulmonary hypertension (PH). PA hemodynamics were evaluated at rest, 2 and 7 min of steady‐state exercise at moderate intensity in patients who exhibited Pre‐capillary (n = 22) and post‐capillary PH (n = 22). Patients with normal exercise hemodynamics (NOR‐HD) (n = 32) were also studied. During exercise in all groups, PA wedge pressure increased at 2 min, with no further change at 7 min. In post‐capillary PH and NOR‐HD, increases in PA diastolic pressure and diastolic pressure gradient remained stable at 2 and 7 min of exercise, while in pre‐capillary PH, both continued to increase at 7 min. The behavior of the diastolic pressure gradient was linearly related to the duration of resistance‐compliance time at rest (r2 = 0.843) and exercise (r2 = 0.760). Exercise resistance‐compliance time was longer in pre‐capillary PH associated with larger increases in diastolic pressure gradient. Conversely, resistance‐compliance time was shortest in post‐capillary PH compared to pre‐capillary PH and NOR‐HD and associated with limited increases in exercise diastolic pressure gradient. During steady‐state, modest‐intensity exercise‐specific patterns of pulmonary vascular afterload responses were observed in pre‐ and post‐capillary PH relative to NOR‐HD. Longer resistance‐compliance time related to greater increases in PA diastolic pressure and diastolic pressure gradients in pre‐capillary PH, while shorter resistance‐compliance time appeared to limit these increases in post‐capillary PH. We assessed patterns of change in hemodynamics and pulmonary vascular afterload over a period of steady‐state exercise in patients with pre‐ and post‐capillary pulmonary hypertension. Patients with normal hemodynamics were also studied. The responses of the resistance‐compliance time, prolonged in pre‐capillary pulmonary hypertension and shortest in post‐capillary pulmonary hypertension, were strongly associated with the diastolic pressure gradient. These differences accounted for the distinctive patterns of change in pulmonary vascular afterload observed between pre‐ and post‐capillary pulmonary hypertension.