Utility of Computed Tomographic Angiography for Pulmonary Hypertension Assessment in a Cohort of West Highland White Terriers With or Without Canine Idiopathic Pulmonary Fibrosis

Abstract

West Highland white terriers (WHWTs) affected with canine idiopathic pulmonary fibrosis (CIPF) are at risk of developing precapillary pulmonary hypertension (PH). In humans, thoracic computed tomography angiography (CTA) is commonly used to diagnose and monitor patients with lower airway diseases. In such patients, CTA helps to identify comorbidities, such as PH, that could negatively impact prognosis. Diameter of the pulmonary trunk (PT), pulmonary trunk-to-aorta ratio (PT/Ao), and right ventricle-to-left ventricle ratio (RV/LV) are CTA parameters commonly used to assess the presence of PH. Pulmonary vein-to-right pulmonary artery ratio (PV/PA) is a new echocardiographic parameter that can be used in dogs to diagnose PH. The primary aim of this study was to evaluate the use of various CTA parameters to diagnose PH. An additional aim was to evaluate the correlation of RV/LV measurements between different CTA planes. CTA and echocardiography were prospectively performed on a total of 47 WHWTs; 22 affected with CIPF and 25 presumed healthy control dogs. Dogs were considered to have PH if pulmonary vein-to-right pulmonary artery ratio (PV/PA) measured on 2D-mode echocardiography was less than to 0.7. WHWTs affected with CIPF had higher PT/Ao compared with control patients. In WHWTs affected with CIPF, PT size was larger in dogs with PH (15.4 mm) compared with dogs without PH (13 mm, p = 0.003). A cutoff value of 13.8 mm predicted PH in WHWTs affected with CIPF with a sensitivity of 90% and a specificity of 87% (AUC = 0.93). High correlations were observed between the different CTA planes of RV/LV. Results suggest that diameter of the PT measured by CTA can be used to diagnose PH in WHWTs with CIPF.

Keywords: West Highland white terrier; canine idiopathic pulmonary fibrosis; computed tomography angiography; pulmonary hypertension; pulmonary trunk.

Figure 1

Post-contrast transverse (A) and manually reformatted (B,C) thoracic computed tomographic angiography (CTA) at the level of the ventricles. (B) Standard four-chamber echocardiographic view (4C); (C) standard short-axis echocardiographic view (SA). Right ventricle (RV) and left ventricle (LV) were measured at their largest diameter.

Figure 2

Post-contrast transverse thoracic computed tomographic angiography (CTA) at the level of the pulmonary trunk. The pulmonary trunk (PT) was assessed just ventral to the division of the pulmonary arteries, and the ascending aorta (Ao) was assessed on the same image.

Figure 3

Post-contrast transverse thoracic computed tomographic angiography (CTA) at the level of the right atrium (RA). The right pulmonary artery (PA) and its adjacent pulmonary vein (PV) were measured dorsal to the right atrium. The pulmonary artery is dorsal and the vein ventral.

Figure 4

Box plot illustrating PT (A), PT/Ao (B), PV/PA measured on CTA (C), and RV/LV (T) (D) according to groups. The whiskers indicate the range of values. The box contains the 25th−75th centiles. The line within the box indicates the median, and the cross indicates the mean. *p < 0.008, significantly different from control without PH; ^†p < 0.008, significantly different from control with PH; ^§p < 0.008, significantly different from CIPF group without PH. PT, pulmonary trunk; PT/Ao, pulmonary trunk-to-aorta ratio; PV/PA, pulmonary vein-to-right pulmonary artery ratio; CTA, computed tomographic angiography; RV/LV (T), right ventricle-to-left ventricle ratio measured on CTA acquired transverse plane; PH, pulmonary hypertension; CIPF, canine idiopathic pulmonary fibrosis.