A rare case of sarcoidosis-associated pulmonary hypertension in a patient exposed to silica

A hypothesis: Potential contributions of metals to the pathogenesis of pulmonary artery hypertension

Pulmonary artery hypertension (PAH) is characterized by vasoconstriction and vascular remodeling resulting in both increased pulmonary vascular resistance (PVR) and pulmonary artery pressure (PAP). The chronic and high-pressure stress experienced by endothelial cells can give rise to inflammation, oxidative stress, and infiltration by immune cells. However, there is no clearly defined mechanism for PAH and available treatment options only provide limited symptomatic relief. Due to the far-reaching effects of metal exposures, the interaction between metals and the pulmonary vasculature is of particular interest. This review will briefly introduce the pathophysiology of PAH and then focus on the potential roles of metals, including essential and non-essential metals in the pathogenic process in the pulmonary arteries and right heart, which may be linked to PAH. Based on available data from human studies of occupational or environmental metal exposure, including lead, antimony, iron, and copper, the hypothesis of metals contributing to the pathogenesis of PAH is proposed as potential risk factors and underlying mechanisms for PAH. We propose that metals may initiate or exacerbate the pathogenesis of PAH, by providing potential mechanism by which metals interact with hypoxia-inducible factor and tumor suppressor p53 to modulate their downstream cellular proliferation pathways. These need further investigation. Additionally, we present future research directions on roles of metals in PAH.

An update on sarcoidosis-associated pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension in sarcoidosis is a well known entity. Sarcoidosis-associated pulmonary hypertension (SAPH) incurs substantial morbidity and mortality. This review examines recent literatures published on epidemiology, prognosis and therapeutic management in SAPH.

RECENT FINDINGS

Several registries have been published between 2017 and 2020. The consensus conclusion - SAPH is a harbinger for poor prognosis. Several factors were noted for predicting adverse outcome in SAPH like reduced 6-min walk distance and diffusing capacity for carbon monoxide. Given its adverse outcome, experts have now focused on methods for early screening of SAPH in sarcoid patients. The exploration of pulmonary vasodilator drugs in SAPH is ongoing. In recent times, trials have been published utilizing Macitentan and parenteral prostacyclin in severe SAPH. Although these trials show encouraging results, the evidence from these studies are limited to approve these agents as preferred drugs for treating SAPH. A large multicentric trial of drugs used for pulmonary arterial hypertension with meaningful, yet feasible, event driven endpoint is still lacking. Lately, interventional treatment by pulmonary artery balloon pulmonary angioplasty and stenting has gained traction for treating pulmonary artery stenosis and chronic thromboembolic pulmonary hypertension. However, the conclusion is still based on small cohorts or case series.

SUMMARY

Several registries have highlighted SAPH portends an unfavorable consequence. On the contrary, no published guideline exists to treat SAPH. The precise role of immunosuppressive agents is unclear. The limited evidence favoring use of pulmonary vasodilators arise from small retrospective case series and/or single-center nonrandomized observational studies. Further multicenter randomized research is warranted to better define patient population to treat and how best to treat them.

Mimickers of chronic thromboembolic pulmonary hypertension on imaging tests: a review

Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by mechanical obstruction of large pulmonary arteries secondary to one or more episodes of pulmonary embolism. Ventilation perfusion scan is the recommended initial screening test for this condition and typically shows multiple large mismatched perfusion defects. However, not all patients with an abnormal ventilation perfusion scan have CTEPH since there are other conditions that be associated with a positive ventilation perfusion scan. These conditions include in situ thrombosis, pulmonary artery sarcoma, fibrosing mediastinitis, pulmonary vasculitis and sarcoidosis, among others. Although these conditions cannot be distinguished from CTEPH using a ventilation perfusion scan, they have certain characteristic radiological features that can be demonstrated on other imaging techniques such as computed tomography scan and can help in differentiation of these conditions. In this review, we have summarized some key clinical and radiological features that can help differentiate CTEPH from the CTEPH mimics.