Pulmonary capillary hemangiomatosis: the role of invasive cardiopulmonary exercise testing

Progression of Pulmonary Veno‐occlusive Disease Without Pulmonary Hypertension

Pulmonary veno‐occlusive disease (PVOD) is a progressively fatal disease with no definitive treatment options. PVOD can be a result of genetic mutation but can also be due secondary to exposure to solvents or chemotherapeutic agents. Generally, at the time of diagnosis PVOD is associated with hemodynamically confirmed pulmonary hypertension (PH). In this study, we describe a patient who was diagnosed with PVOD early in the disease without hemodynamically confirmed PH. She had histologically confirmed PVOD. Her clinical presentation posed management challenges and prednisone therapy was used to stabilize her disease. This case and some recently published reports highlight possible immune dysregulation in PVOD and role for immuno‐suppressive therapy in these patients.

Pulmonary arterial hypertension associated with pulmonary arteriovenous malformations and pulmonary veno-occlusive disease: A devastating combination

We describe a case of an adolescent male with the rare combination of pulmonary arterial hypertension (PAH) and pulmonary arteriovenous malformations (PAVM's) without confirmed hereditary hemorrhagic telangiectasia (HHT). The patient showed clinical deterioration on standard vasodilator therapy, leading us to question our initial diagnosis. Post-mortem evaluation confirmed the presence of pulmonary veno-occlusive disease of which no conclusive signs were recognized at diagnostic work-up. This case demonstrates the heterogeneity in the diseases causing PAH and shows that an unexpected treatment response should alert the physician to question the original diagnosis.

Mapping cardiopulmonary dynamics within the microvasculature of the lungs using dissolved 129Xe MRI

Magnetic resonance (MR) imaging and spectroscopy using dissolved hyperpolarized (HP) 129Xe have expanded the ability to probe lung function regionally and noninvasively. In particular, HP 129Xe imaging has been used to quantify impaired gas uptake by the pulmonary tissues. Whole-lung spectroscopy has also been used to assess global cardiogenic oscillations in the MR signal intensity originating from 129Xe dissolved in the red blood cells of pulmonary capillaries. Herein, we show that the magnitude of these cardiogenic dynamics can be mapped three dimensionally using radial MRI, because dissolved 129Xe dynamics are encoded directly in the raw imaging data. Specifically, 1-point Dixon imaging is combined with postacquisition keyhole image reconstruction to assess regional blood volume fluctuations within the pulmonary microvasculature throughout the cardiac cycle. This "oscillation mapping" was applied in healthy subjects (mean amplitude 9% of total RBC signal) and patients with pulmonary arterial hypertension (PAH; mean 4%) and idiopathic pulmonary fibrosis (IPF; mean 14%). Whole-lung mean values from these oscillation maps correlated strongly with spectroscopy and clinical pulmonary function testing, but exhibited significant regional heterogeneity, including gravitationally dependent gradients in healthy subjects. Moreover, regional oscillations were found to be sensitive to disease state. Greater percentages of the lungs exhibit low-amplitude oscillations in PAH patients, and longitudinal imaging shows high-amplitude oscillations increase significantly over time (4-14 mo, P = 0.02) in IPF patients. This technique enables regional dynamics within the pulmonary capillary bed to be measured, and in doing so, provides insight into the origin and progression of pathophysiology within the lung microvasculature.NEW & NOTEWORTHY Spatially heterogeneous abnormalities within the lung microvasculature contribute to pathology in various cardiopulmonary diseases but are difficult to assess noninvasively. Hyperpolarized 129Xe MRI is a noninvasive method to probe lung function, including regional gas exchange between pulmonary air spaces and capillaries. We show that cardiogenic oscillations in the raw dissolved 129Xe MRI signal from pulmonary capillary red blood cells can be imaged using a postacquisition reconstruction technique, providing a new means of assessing regional lung microvasculature function and disease state.

Capillary Proliferation in Systemic-Sclerosis-Related Pulmonary Fibrosis: Association with Pulmonary Hypertension

Objective

We sought to determine if any histopathologic component of the pulmonary microcirculation can distinguish systemic sclerosis (SSc)‐related pulmonary fibrosis (PF) with and without pulmonary hypertension (PH).

Methods

Two pulmonary pathologists blindly evaluated 360 histologic slides from lungs of 31 SSc‐PF explants or autopsies with (n = 22) and without (n = 9) PH. The presence of abnormal small arteries, veins, and capillaries (pulmonary microcirculation) was semiquantitatively assessed in areas of preserved lung architecture. Capillary proliferation (CP) within the alveolar walls was measured by its distribution, extent (CP % involvement), and maximum number of layers (maximum CP). These measures were then evaluated to determine the strength of their association with right heart catheterization–proven PH.

Results

Using consensus measures, all measures of CP were significantly associated with PH. Maximum CP had the strongest association with PH (P = 0.013; C statistic 0.869). Maximum CP 2 or more layers and CP % involvement 10% or greater were the optimal thresholds that predicted PH, both with a sensitivity of 56% and specificity of 91%. The CP was typically multifocal rather than focal or diffuse and was associated with a background pattern of usual interstitial pneumonia. There was a significant but weaker relationship between the presence of abnormal small arteries and veins and PH.

Conclusion

In the setting of advanced SSc‐PF, the histopathologic feature of the pulmonary microcirculation best associated with PH was capillary proliferation in architecturally preserved lung areas.