Pulmonary Hypertension and Computed Tomography Measurement of Small Pulmonary Vessels in Severe Emphysema

Abstract

Rationale: Vascular alteration of small pulmonary vessels is one of the characteristic features of pulmonary hypertension in chronic obstructive pulmonary disease. The in vivo relationship between pulmonary hypertension and morphological alteration of the small pulmonary vessels has not been assessed in patients with severe emphysema. Objectives: We evaluated the correlation of total cross-sectional area of small pulmonary vessels (CSA) assessed on computed tomography (CT) scans with the degree of pulmonary hypertension estimated by right heart catheterization. Methods: In 79 patients with severe emphysema enrolled in the National Emphysema Treatment Trial (NETT), we measured CSA less than 5 mm 2 (CSA ,5 ) and 5 to 10 mm 2 (CSA 5210 ), and calculated the percentage of total CSA for the lung area (%CSA ,5 and %CSA 5-10 , respectively). The correlations of %CSA ,5 and %CSA 5-10 with pulmonary arterial mean pressure (Ppa) obtained by right heart catheterization were evaluated. Multiple linear regression analysis using Ppa as the dependent outcome was also performed. Measurements and Main Results: The %CSA ,5 had a significant negative correlation with Ppa (r 5 20.512, P , 0.0001), whereas the correlation between %CSA 5-10 and Ppa did not reach statistical significance (r 5 20.196, P 5 0.083). Multiple linear regression analysis showed that %CSA ,5 and diffusing capacity of carbon monoxide (DL CO ) % predicted were independent predictors of Ppa (r 2 5 0.541): %CSA ,5 (P , 0.0001), and DL CO % predicted (P 5 0.022). Conclusions: The %CSA ,5 measured on CT images is significantly correlated to Ppa in severe emphysema and can estimate the degree of pulmonary hypertension.Keywords: chronic obstructive pulmonary disease; emphysema; pulmonary hypertension; CT Pulmonary hypertension is an important predictor of mortality in chronic obstructive pulmonary disease (COPD) (1-3). Various factors, including endothelial dysfunction, inflammation, and hypoxia, have been recognized as potential contributors to the development of secondary pulmonary hypertension in emphysema, but its pathogenesis has not been fully clarified. Nevertheless, it is generally recognized that vascular remodeling of small pulmonary arteries is an essential morphological feature of pulmonary hypertension; narrowing and diminution of the small pulmonary vessels have been shown on conventional angiography in emphysema (4-6). However, to our knowledge, the in vivo relationship between pulmonary hypertension and the magnitude of small pulmonary vessel morphological change has not been quantitatively assessed in severe emphysema.A recent histological study suggested that vascular remodeling leads to reduced distensibility of small pulmonary vessels and that this remodeling is closely related to pulmonary hypertension (7). Such a decrease in distensibility of small pulmonary vessels may lead to increased pulmonary vascular resistance and elevated pulmonary vascular pressure. Therefore, we hypothesized that measurements of the total cross-sectional area of small ...

CT Scan-Measured Pulmonary Artery to Aorta Ratio and Echocardiography for Detecting Pulmonary Hypertension in Severe COPD

“…The area under the curve for the PA:A ratio was 0.83 (95% CI, 0.72-0.93; ible, requires minimal training, and performs better than echocardiography for the identifi cation of PH in patients with severe COPD. 11,16,26,27 Estimates of the prevalence of PH in COPD vary widely from as low as 10% to as high as 85% depending on the severity of the underlying lung disease and the diagnostic criteria as well as approach used. 11,[28][29][30] Accurate estimates have also been problematic, because RHC is not routinely used in patients with COPD, particularly in those with moderate disease.…”

“…However, most of these studies were conducted in heterogeneous populations with various underlying lung diseases, thus, limiting their application to patients with COPD. [14][15][16][17][18][19][20] We showed that CT image-measured relative PA enlargement, defined as a PA:A ratio . 1, identifies patients at increased risk of COPD exacerbation and hospitalization 21 ; however, the mechanism underlying relative PA enlargement has not been clearly elucidated.…”

“…1, identifies patients at increased risk of COPD exacerbation and hospitalization 21 ; however, the mechanism underlying relative PA enlargement has not been clearly elucidated. 16,22 Although increases in the PA:A ratio could represent resting PH, other factors may contribute, including left ventricular dysfunction and hyperinfl ation due to emphysema. We hypothesized that the PA:A ratio would correlate with mean PA pressure (mPAP) by RHC and that the presence of PA:A .…”

Changes in the Cross-sectional Area of Pulmonary Small Vessels Assessed via Chest Computed Tomography after Interventional Bronchoscopy in Patients with Airway Obstruction Due to a Malignant Disease

“…Matsuoka reported that the %CSA<5 was found to have a negative correlation with the extent of emphysema, degree of airflow limitation, and severity of pulmonary hypertension [15][16][17] . Further, Karayama reported that the %CSA<5 significantly decreased after chemotherapy and mentioned that this result was indicative of the potential vascular toxicity induced by chemotherapy 18) .…”

“…CT measurements of pulmonary CSA have been described in previous literature 17,18) . In brief, the following procedures were performed.…”