Association of abnormal pulmonary vasculature on CT scan for COVID-19 infection with decreased diffusion capacity in follow up: A retrospective cohort study.

BACKGROUND: Coronavirus Disease 2019 (COVID-19) is a respiratory viral illness causing pneumonia and systemic disease. Abnormalities in pulmonary function tests (PFT) after COVID-19 infection have been described. The determinants of these abnormalities are unclear. We hypothesized that inflammatory biomarkers and CT scan parameters at the time of infection would be associated with abnormal gas transfer at short term follow-up. METHODS: We retrospectively studied subjects who were hospitalized for COVID-19 pneumonia and discharged. Serum inflammatory biomarkers, CT scan and clinical characteristics were assessed. CT images were evaluated by Functional Respiratory Imaging with automated tissue segmentation algorithms of the lungs and pulmonary vasculature. Volumes of the pulmonary vessels that were ≤5mm (BV5), 5-10mm (BV5_10), and ≥10mm (BV10) in cross sectional area were analyzed. Also the amount of opacification on CT (ground glass opacities). PFT were performed 2-3 months after discharge. The diffusion capacity of carbon monoxide (DLCO) was obtained. We divided subjects into those with a DLCO <80% predicted (Low DLCO) and those with a DLCO ≥80% predicted (Normal DLCO). RESULTS: 38 subjects were included in our cohort. 31 out of 38 (81.6%) subjects had a DLCO<80% predicted. The groups were similar in terms of demographics, body mass index, comorbidities, and smoking status. Hemoglobin, inflammatory biomarkers, spirometry and lung volumes were similar between groups. CT opacification and BV5 were not different between groups, but both Low and Normal DLCO groups had lower BV5 measures compared to healthy controls. BV5_10 and BV10 measures were higher in the Low DLCO group compared to the normal DLCO group. Both BV5_10 and BV10 in the Low DLCO group were greater compared to healthy controls. BV5_10 was independently associated with DLCO<80% in multivariable logistic regression (OR 1.29, 95% CI 1.01, 1.64). BV10 negatively correlated with DLCO% predicted (r = -0.343, p = 0.035). CONCLUSIONS: Abnormalities in pulmonary vascular volumes at the time of hospitalization are independently associated with a low DLCO at follow-up. There was no relationship between inflammatory biomarkers during hospitalization and DLCO. Pulmonary vascular abnormalities during hospitalization for COVID-19 may serve as a biomarker for abnormal gas transfer after COVID-19 pneumonia.

A novel BMPR2 mutation with widely disparate heritable pulmonary arterial hypertension clinical phenotype.

Mutations in the gene encoding bone morphogenetic protein receptor type II (BMPR2) have been associated with heritable pulmonary arterial hypertension (HPAH), whereas mutations in the gene encoding eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) are associated with heritable pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis (HPVOD/PCH). We describe two unrelated patients found to carry the same hitherto unreported pathogenic BMPR2 mutation; one of whom presented with typical pulmonary arterial hypertension, whereas the second patient presented with aggressive disease and characteristic clinical features of PVOD/PCH. These two clinically divergent cases representative of the same novel pathogenic mutation exemplify the variable phenotype of HPAH and the variable involvement of venules and capillaries in the pathology of the pulmonary vascular bed in pulmonary arterial hypertension.

Transition from selexipag to oral treprostinil in a patient with pulmonary arterial hypertension.

Prostacyclins are the mainstay treatment for patients with severe pulmonary arterial hypertension. This case highlights the transition from selexipag to oral treprostinil. Our patient improved both subjectively and objectively. Cardiac output and index, as measured by the echocardiogram, improved 12% and 7.7%, respectively. Invasive hemodynamic data revealed greater improvements: cardiac output improved by 25% and cardiac index by 28%. Mixed venous oxygen saturation improved from 65% to 71%. A possible explanation is that selexipag has a maximal dose, whereas there is no recommended maximum dose of oral treprostinil. Another theory is oral treprostinil has higher affinity to the IP receptor, though selexipag has a higher specificity. However, there are no bio-equivalency data, and data comparing pharmacodynamics of both drugs are lacking. Furthermore, no head-to-head trials comparing these agents exist.