Abstract
Echocardiography was performed to obtain the optimal planes for diagnosis of canine heartworm disease in 11 dogs. Imaging planes were taken the left ventricular outflow tract long-axis view, 4-chamber long-axis view, chordae tendineae level short-axis view and modified pulmonary arteries level short-axis view in the right parasternal window, and aptical 4-chamber long-axis view in hte left parasternal window. After echocaridography, the pulmonary artery valve pat was ligated with double 1-0 silk under the general anesthesia to prevent heartworm moving from pulmonary artery to right ventricle. The dogs were euthanized and examained for heartworms in heart and great vessels. Many adult heartworms were identified ultrasonographically within main pulmonary artery, bifurcation of pulmonary artery and right pulmonary artery, but not identified within right ventricle and atrium. At necropsy, adult heartworms were mainly found in pulmonary artery in 11 days, and also found in right ventricular outflow tract and right ventricle in 2 of 11 dogs. The modified pulmonary arteries level short-axis view was the best imaging plane for identifiying heartworms because the main pulmonary artery, branches of pulmonary artery and right pulmonary artery could be showed. The aortic root internal dimension (AOID) and right pulmonary atery internal dimension (RPAID) were measured from the modified pulmonary ateries level short-axis view and left ventricular outflow tract long-axis view. The RPAID and RPAID/AOID was higher in heartworm infected dogs than normal Korea Jin-do dogs in modified pulmonary arteries level short-axis view, and the AOID, RPAID and RPIAID/AOID was higher than in left ventricular outflow tract long-axis view, respectively. These results indicate that the pulmonary arteries were the major habitat of adult heartworm in canine heartworm disease and the modified pulmonary arteries level short-axis view was the best imaging planes for identifying heartworms because the main pulmonary arteries could be showed. Therefore the modified pulmonary arteries level short-axis view can be used for diagnosing heartworm disease and for monitoring dilation of pulmonary artery.
