Electrocardiographic alterations in dogs with heartworm disease (Dirofilaria immitis)

Abstract

Heartworm disease (Dirofilaria immitis) is widely distributed in geographic areas with high humidity and temperature where mosquitoes act as vectors of transmission. The parasite affects the pulmonary arteries and the right side of the heart in advanced stages, so by performing chest X-rays, echocardiogram and electrocardiogram (ECG) it is possible to check the cardiac alterations produced by the presence of the parasite. The aim of this study was to evaluate the clinical usefulness of the ECG performed on dogs with heartworm by determining the prevalence of ECG abnormalities as well as by determining its utility in assessing the clinical stage, by comparing the results with other clinical parameters. Sixty-two heartworm-infected dogs participated in the study. Patients were classified according to their symptoms; microfilaremia was assessed, thoracic radiology and echocardiographic measurements for pulmonary arterial pressure and parasite load were obtained, as well as ECGs were performed. The ECGs performed showed alterations in 48.4% of the dogs, being changes mostly related to right sided cardiac damage and respiratory disease, although only significant differences were observed between the presence of pathological Q-wave voltage and the presence of PH. As heartworm is characterized by presence of pulmonary hypertension, parenchymal lung alterations and right-sided heart congestive failure, the detection of electric disturbances in infected dogs since early stages may help to determine the severity of the disease and to monitor the cardiorespiratory status of these dogs.