Clinical correlates of angiographically diagnosed idiopathic pulmonary hypertension

Vascular remodeling of the small pulmonary arteries and measures of vascular pruning on computed tomography

Pulmonary hypertension is characterized histologically by intimal and medial thickening in the small pulmonary arteries, eventually resulting in vascular “pruning.” Computed tomography (CT)-based quantification of pruning is associated with clinical measures of pulmonary hypertension, but it is not established whether CT-based pruning correlates with histologic arterial remodeling. Our sample consisted of 138 patients who underwent resection for early-stage lung adenocarcinoma. From histologic sections, we identified small pulmonary arteries and measured the relative area comprising the intima and media (VWA%), with higher VWA% representing greater histologic remodeling. From pre-operative CTs, we used image analysis algorithms to calculate the small vessel volume fraction (BV5/TBV) as a CT-based indicator of pruning (lower BV5/TBV represents greater pruning). We investigated relationships of CT pruning and histologic remodeling using Pearson correlation, simple linear regression, and multivariable regression with adjustment for age, sex, height, weight, smoking status, and total pack-years. We also tested for effect modification by sex and smoking status. In primary models, more severe CT pruning was associated with greater histologic remodeling. The Pearson correlation coefficient between BV5/TBV and VWA% was –0.41, and in linear regression models, VWA% was 3.13% higher (95% CI: 1.95–4.31%, p < 0.0001) per standard deviation lower BV5/TBV. This association persisted after multivariable adjustment. We found no evidence that these relationships differed by sex or smoking status. Among individuals who underwent resection for lung adenocarcinoma, more severe CT-based vascular pruning was associated with greater histologic arterial remodeling. These findings suggest CT imaging may be a non-invasive indicator of pulmonary vascular pathology.

The Pathobiology of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension is characterized by obliteration and obstruction of the pulmonary arterioles that in turn results in high right ventricular afterload and right heart failure. The pathobiology of pulmonary arterial hypertension is complex, with contributions from multiple pathophysiologic processes that are regulated by a variety of molecular mechanisms. This nature likely explains the limited efficacy of our current therapies, which only target a small portion of the pathobiological mechanisms that underlie advanced disease. Here we review the pathobiology of pulmonary arterial hypertension, focusing on the systemic, cellular, and molecular mechanisms that underlie the disease.

Pulmonary nuclear medicine

This article reviews the contribution made by nuclear imaging to the assessment, diagnosis and monitoring of patients with respiratory disease. It focuses on several specific areas including the diagnosis of pulmonary embolism, the investigation of intrapulmonary infection and neoplasm and the role of positron emission tomography (PET) scanning.