Pulmonary veno-occlusive disease associated with hypertrophic cardiomyopathy

Evidence of Advanced Pulmonary Vascular Remodeling in Obstructive Hypertrophic Cardiomyopathy With Pulmonary Hypertension

BACKGROUND

Elevated mean pulmonary artery pressure (mPAP) is common in patients with hypertrophic cardiomyopathy (HCM) and heart failure symptoms. However, dynamic left ventricular (LV) outflow tract obstruction may confound interpretation of pulmonary hypertension (PH) pathophysiologic features in HCM when relying on resting invasive hemodynamic data alone.

RESEARCH QUESTION

Do structural changes to the lung vasculature clarify PH pathophysiologic features in patients with HCM with progressive heart failure?

STUDY DESIGN AND METHODS

Clinical data and ultrarare lung autopsy specimens were acquired retrospectively from the National Institutes of Health (1975-1992). Patients were included based on the availability of lung tissue and recorded mPAP. Discarded tissue from rejected lung donors served as control specimens. Histomorphology was performed on pulmonary arterioles and veins. Comparisons were calculated using the Student t test and Mann-Whitney U test; Pearson correlation was used to assess association between morphometric measurements and HCM cardiac and hemodynamic measurements.

RESULTS

The HCM cohort (n = 7; mean ± SD age, 43 ± 18 years; 71% men) showed maximum mean ± SD LV wall thickness of 25 ± 2.8 mm, mean ± SD outflow tract gradient of 90 ± 30 mm Hg, median mPAP of 25 mm Hg (interquartile range [IQR], 6 mm Hg), median pulmonary artery wedge pressure (PAWP) of 16 mm Hg (IQR, 4 mm Hg), and median pulmonary vascular resistance of 1.8 Wood units (WU; IQR, 2.4 WU). Compared with control samples (n = 5), patients with HCM showed greater indexed pulmonary arterial hypertrophy (20.7 ± 7.2% vs 49.7 ± 12%; P < .001) and arterial wall fibrosis (11.5 ± 3.4 mm vs 21.0 ± 4.7 mm; P < .0001), which correlated with mPAP (r = 0.84; P = .018), PAWP (r = 0.74; P = .05), and LV outflow tract gradient (r = 0.78; P = .035). Compared with control samples, pulmonary vein thickness was increased by 2.9-fold (P = .008) in the HCM group, which correlated with mPAP (r = 0.81; P = .03) and LV outflow tract gradient (r = 0.83; P = .02).

INTERPRETATION

To the best of our knowledge, these data demonstrate for the first time that in patients with obstructive HCM, heart failure is associated with pathogenic pulmonary vascular remodeling even when mPAP is elevated only mildly. These observations clarify PH pathophysiologic features in HCM, with future implications for clinical strategies that mitigate outflow tract obstruction.

Pulmonary veno-occlusive disease in childhood-a rare disease not to be missed

Pulmonary veno-occlusive disease (PVOD) is a rare disease leading to pulmonary hypertension and potentially death related to right heart failure and/or respiratory insufficiency. Clinical symptoms are heterogenous and nonspecific: fatigue, decreased exercise tolerance, shortness of breath on exertion, cough, dizziness, chest pain with exercise, palpitations, syncope, as well as nonspecific symptoms such as headache, poor appetite, pallor or perioral cyanosis. Mutations in the EIF2AK4 (eukaryotic translation initiation factor 2-alpha kinase 4) have been recently described, other risk factors include exposure to organic solvent and trichloroethylene, tobacco exposure and chemotherapy. Echocardiography helps to estimate right ventricular systemic pressure, but further diagnostic workup includes cardiac catheterization to confirm pulmonary hypertension and increased pulmonary vascular resistance. High-resolution computed tomography reveals typical findings: centrilobular ground-glass nodules or opacities, septal lines, thickened interlobular septa, mosaic perfusion, and lymphadenopathy. Histology remains the gold standard, but carries risks for the patient. Proper workup is essential in order to avoid incorrect diagnosis. Pulmonary hypertension targeted treatment has been used in patients with PVOD, however, experience is limited, vasodilatory effects on pulmonary vasculature may lead to deterioration of the patients and should be used with great caution. Lung transplantation is currently the only valid treatment option for patients with PVOD. With prolonged waiting time and progression of the disease mechanical support could be considered.