According to a recent study, axial strain in the proximal pulmonary artery (PPA) decreases by 7% per decade and circumferential strain by 20% every 10 years after age 50.
The study, published in Physiological Reports, investigated age-related changes in the human PPA and their implications for lung and right ventricular function. Researchers conducted a comprehensive analysis combining in vivo data from 6 patients with ex vivo data from 8 cadavers and 13 organ donors, spanning ages 18 to 89 years. The study aimed to assess the associations between aging and changes in PPA distensibility, biaxial wall strain, wall thickness, vessel diameter, and wall composition.
In vivo data were obtained using cardiac magnetic resonance imaging (MRI) and right heart catheterization from six patients at Yale-New Haven Hospital. The demographic information included ages ranging from 51 to 78 years, with an average age of 63. MRI scans assessed the circumferential and axial strains of the PPA, while diffusion capacity of the lung (DLCO) and right ventricular ejection fraction (RVEF) were also measured. Ex vivo analyses involved 21 tissue samples from cadavers and 13 samples from organ donors. Morphometric analysis of the PPA included wall thickness, luminal radius, and length, while histological analyses determined the proportions of elastin and collagen.
The results showed significant negative associations between age and both distensibility and cyclic biaxial strain of the PPA. For every 10 years after age 50, circumferential and axial strains decreased by approximately 20% and 7%, respectively (P ≤ 0.05). Distensibility was directly associated with DLCO (R² = 0.71, P = 0.03), and axial strain was associated with RVEF (R² = 0.76, P = 0.02). These findings suggested that age-related stiffening of the PPA may negatively impact lung and right ventricular function, noted researchers.
The ex vivo analysis revealed that aging was associated with significant increases in the length (P = 0.004) and luminal diameter (P = 0.05) of the PPA, but no significant changes in mean wall thickness (1.19 mm, P = 0.61) or the proportions of mural elastin and collagen (P = 0.19). Researchers noted this indicated that microstructural remodeling, rather than changes in overall geometry, may explain the observed age-related stiffening.
The study concluded that age-related stiffening of the PPA differs from that of the aorta and may contribute to the decline in lung function seen with aging.
“By associating age‐related changes in structure with age‐related decline in cardiopulmonary function, we believe that this study provides new insights into potential mechanisms for the decline in lung function that accompanies ‘healthy aging’,” stated researchers.
They also noted future studies should explore extracellular matrix changes beyond collagen and elastin quantification to understand tissue-level mechanisms, along with related cellular and molecular research.
Full list of disclosures can be found in the original study.
