Global Pulmonary Vascular Remodeling and Pulmonary Hypertension in Heart Failure

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The severity of pulmonary vascular remodeling was associated with reductions in the diffusing capacity of the lungs.
The severity of pulmonary vascular remodeling was associated with reductions in the diffusing capacity of the lungs.

An association exists between pulmonary hypertension (PH) and global pulmonary vascular remodeling in patients with heart failure (HF), with thickening of small and venous indeterminate vessels strongly correlating with PH severity in these patients, according to study findings published in Circulation.

Investigators evaluated patients with HF and PH (n=108) and compared these patients with healthy controls (n=12) and patients with primary pulmonary veno-occlusive disease (PVOD; n=17). For this study, PH was defined as a pulmonary artery systolic pressure (PASP) ≥40 mm Hg. A quantitative histomorphometry was conducted in small indeterminate vessels (n=2168), veins (n=7630), and arteries (n=4949) in lung specimens.

Patients with HF and PH had a higher average percentage of medial thickness, intimal thickness, and venous intimal thickness than controls (P <.0001 for all). Despite these higher values, patients with HF and PH demonstrated lower levels of primary PVOD compared with the control group (P ≤.005 for all).

In addition, PVOD (91 [interquartile range, 82-103]) was higher than PASP (median 59 [interquartile range, 50-70]) in HF-PH, yet PASP was higher in patients with HF and PH with right ventricular dysfunction. Overall, PASP correlated strongly with venous percentage intimal thickness (r=0.49) and indeterminate vessel percentage intimal thickness (r=0.55; P <.0001 for all).

In 30 patients with HF and PH and 14 patients with PVOD undergoing right heart catheterization, investigators observed associations between pulmonary vascular remodeling and the transpulmonary gradient. In this cohort, researchers found that the severity of pulmonary vascular remodeling was associated with reductions in the diffusing capacity of the lungs. No overall differences existed between the groups with regard to the severity of pulmonary vascular remodeling.

The investigators did not perform invasive assessment of pulmonary hemodynamics or pulmonary function tests, which may have limited the findings.

However, this study does have several clinical implications, particularly in patients with HF, arterial medial thickening “reflects a hypertrophic response to the downstream obstruction provided both by the venous and [indeterminate vessel] remodeling as well as the chronic pulmonary venous hypertension related to their underlying left heart disease.”

Reference

Fayyaz AU, Edwards WD, Maleszewski JJ, et al. Global pulmonary vascular remodeling in pulmonary hypertension associated with heart failure and preserved or reduced ejection fraction [published online December 15, 2017]. Circulation. doi:10.1161/CIRCULATIONAHA.117.031608

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