Usefulness of tissue doppler imaging for the evaluation of pulmonary hypertension in canine heartworm disease

Abstract

Dirofilaria immitis is a nematode that produces proliferative pulmonary endarteritis in dogs due to direct contact of the adult parasites with the intima layer of the pulmonary arteries. The vascular lesions lead to an irreversible structural damage and a sustained pulmonary hypertension (PH) which can produce dyspnoea, exercise intolerance, cough, or even right heart failure. The purpose of this study was to assess the diagnostic value of the echocardiography tissue doppler imaging (TDI) to determine the presence of PH in dogs with heartworm disease. 116 heartworm-infected dogs and 33 healthy dogs were included in the study. Based on the right pulmonary artery distensibility index (RPADi), PH was present in 47,4% of dogs infected by Dirofilaria immitis and compared with other alternative measures for estimation of PH (PT:Ao, TRPG, TAPSE, AT:ET and PV:PA ratio). A total of 8 echocardiographic measurements were analyzed: E', A´, S, E':A', Global TDI, HRI-IVCT, HRI-IVRT, R-TEI. There were significant differences and high positive correlation, with a high sensitivity and specificity, between the values of the TDI measures and the combination of disease and PH, with the exception of the A' measure. The TDI mode measures may be useful as a complementary diagnostic method for the determination of PH in dogs with Dirofilaria immitis. However, further research with a greater number of dogs must be carried out to confirm these results.