Impact of chronic hypoxia on proximal pulmonary artery wave propagation and mechanical properties in rats

Abstract

Arterial stiffness and wave reflection are important components of the ventricular afterload. Therefore, we aimed to assess the arterial wave characteristics and mechanical properties of the proximal pulmonary arteries (PAs) in the hypoxic pulmonary hypertensive rat model. After 21 days in normoxic or hypoxic chambers (24 animals/group), animals underwent transthoracic echocardiography and PA catheterization with a dual-tipped pressure and Doppler flow sensor wire. Wave intensity analysis was performed. Artery rings obtained from the pulmonary trunk, right and left PAs, and aorta were subjected to a tensile test to rupture. Collagen and elastin content were determined. In hypoxic rats, proximal PA wall thickness, collagen content, tensile strength per unit collagen, maximal elastic modulus, and wall viscosity increased, whereas the elastin-to-collagen ratio and arterial distensibility decreased. Arterial pulse wave velocity was also increased, and the increase was more prominent in vivo than ex vivo. Wave intensity was similar in hypoxic and normoxic animals with negligible wave reflection. In contrast, the aortic maximal elastic modulus remained unchanged, whereas wall viscosity decreased. In conclusion, there was no evidence of altered arterial wave propagation in proximal PAs of hypoxic rats while the extracellular matrix protein composition was altered and collagen tensile strength increased. This was accompanied by altered mechanical properties in vivo and ex vivo.NEW & NOTEWORTHY In rats exposed to chronic hypoxia, we have shown that pulse wave velocity in the proximal pulmonary arteries increased and pressure dependence of the pulse wave velocity was steeper in vivo than ex vivo leading to a more prominent increase in vivo.

Study of the Effect of Treatment With Atrial Natriuretic Peptide (ANP) and Cinaciguat in Chronic Hypoxic Neonatal Lambs on Residual Strain and Microstructure of the Arteries

“…To quantify the behavior of pathological tissue, several biomechanical ex vivo assessments, such as uniaxial tensile, wire myograph, pressurization (inflation-extension), and biaxial tests have been established (Karimi et al, 2013;Pichamuthu et al, 2013;Cañas et al, 2017). Su et al (2018) studied the impact of chronic hypoxia on pulmonary artery according to its mechanical properties and wave propagation capacity. In particular, uniaxial tensile test to rupture and under loading-unloading cycles were performed to determine arterial stiffness and viscoelastic properties on normoxic and hypoxic groups; from this analysis, significant differences were observed in viscoelasticity behavior, which decreased in hypoxic groups.…”

A multiscale model of vascular function in chronic thromboembolic pulmonary hypertension

“…We observe similar trends in cases (b) and (c), which introduce narrowing and stiffening of the small vessels. Though cases (a)-(c) increase the mean MPA pressure, typical CTEPH patients have a systolic MPA pressure > 55 mmHg [53]. We approach this in case (d), which also dilates and stiffens the large pulmonary arteries.…”

“…Wave intensity analysis (WIA) is a time-domain decomposition of forward and backward waves and is utilized in understanding the progression of cardiovascular disease [40,42,53]. The so-called pressure and velocity 'wavefronts' [54] δp ± and δu ± are calculated as…”

Cystamine Treatment Fails to Prevent the Development of Pulmonary Hypertension in Chronic Hypoxic Rats

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