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.

Evaluation of Pulmonary Hypertension in Dogs with Heartworm Disease Using the Computed Tomographic Pulmonary Trunk to Aorta Diameter Ratio

“…In this study, unlike the RPAD index, the PT:Ao ratio did not show significant differences between healthy dogs and dogs with heartworm without hypertension or mild PH. These results are similar to those reported in previous investigations, which showed a high degree of overlap between PT:Ao ratios of the non-PH and mild-PH groups [ 9 , 10 , 11 ].…”

“…The cut-off point to diagnose moderate or severe PH reported for PT:DAo in this study (≥1.111) was slightly lower than previously reported by other authors (> 1.4) in dogs with PH of undescribed etiology [ 10 ]. Moreover, the mean PT:AAo and PT:DAo obtained for healthy dogs were slightly lower than the values presented in previous studies (1.11 ± 0.15 and 0.97 ± 0.12 for PT:AAo, and 1.26 ± 0.11 for PT:DAo) [ 9 , 10 , 11 ]. These differences could be due to the different methodologies established to determine the presence or absence of PH in the studies mentioned.…”

“…The study of the PT:Ao ratio via CT in humans has previously been reported [ 12 , 13 , 14 ], in which the increase in the diameter of the pulmonary trunk compared with the descending and the ascending portions of the thoracic aorta have been shown to have a strongly predictive value of PH, and cut-off points were established to determine the presence of even mild PH [ 14 ]. In veterinary medicine, recent studies have also been published on the PT:Ao ratio with the objective of establishing physiological measures in healthy animals and to establish cut-off points to diagnose the presence and severity of PH [ 9 , 10 , 11 ]. In this study, unlike the RPAD index, the PT:Ao ratio did not show significant differences between healthy dogs and dogs with heartworm without hypertension or mild PH.…”

“…Although echocardiography is the method of choice to estimate the presence or absence of PH, in veterinary practice, helical thoracic computed tomography (CT) is becoming more widely available and used more frequently for the evaluation of cardiorespiratory diseases in small animals [ 8 ]. Moreover, recent studies have shown the usefulness of CT in the diagnosis of PH in the canine species [ 9 , 10 , 11 ]; although, to date, there are no published specific indicators of PH in dogs with heartworm.…”

“…The use of angiography through CT and the quantitative measure of the diameters of the pulmonary trunk (PT) and the aorta (Ao), translated into the PT:Ao ratio, constitutes a clinical parameter routinely used to aid in the diagnosis of PH in humans, which has also demonstrated an objective value in veterinary medicine in comparison with echocardiography [ 9 , 10 , 11 , 12 , 13 , 14 ]. The recent use of the PT:Ao ratio has shown that dogs with moderate and severe PH had significantly higher PT:Ao ratios than healthy dogs and dogs with mild PH in a study carried out with dogs with idiopathic pulmonary fibrosis [ 11 ]. Furthermore, there are two different measurement methods of the PT:Ao ratio, which are based on the size of the descending aorta (DAo) or the ascending aorta (AAo).…”