Case Study

Right sided heart failure in a heartworm-positive MI mixed breed dog with abdominal distension

An intact male mixed breed dog of unknown age was presented for evaluation of 4-5 days of progressive abdominal distension. Abnormalities on laboratory work included anemia and a positive heartworm test. Survey radiographs showed cardiomegaly and a possible abdominal mass.

An intact male mixed breed dog of unknown age was presented for evaluation of 4-5 days of progressive abdominal distension. Abnormalities on laboratory work included anemia and a positive heartworm test. Survey radiographs showed cardiomegaly and a possible abdominal mass.

DX

Heartworms, pulmonary hypertension

Sonographic Differential Diagnosis

Right sided heart failure. A large number of heartworms was noted in the main branch of the pulmonary artery. Pulmonary hypertension was noted.

Image Interpretation

The echocardiogram revealed an enlarged right heart with right atrial enlargement and significant tricuspid regurgitation. Tricuspid insufficiency was noted at a velocity of 3.87 m/sec. The main branch of the pulmonary artery was enlarged, and a large amount of heartworms was noted. Smoke was evident in the right atrium. The mitral valve was also insufficient with a velocity of 5.56 m/sec, however the left atrium was of normal size.

Outcome

No further outcome.

Comments

Ideally, it would be prudent to perform a blood pressure and ECG in this patient. Given the changes seen on echocardiographic examination this patient would be an ideal candidate for basket retrieval of heartworms. Until this procedure is performed the patient should be treated with aspirin at 1 mg/kg every other day, Pimobendan at 0.25-0.3 mg/kg b.i.d. and Sildenafil at 1 mg/kg b.i.d. The Sildenafil dose can be increased to 1.5 mg/kg b.i.d. over 10 days. Lasix should be instituted at 1-2 mg s.i.d. Given the significant amount of heartworms noted in the pulmonary artery coupled with the patient’s clinical signs the patient’s prognosis is guarded at this time.

Clinical Differential Diagnosis

Cardiac – right heart failure secondary to heartworm, pericardial effusion, cardiomyopathy. Abdominal mass – neoplasia, granuloma, abscess or cyst of the spleen, liver, or kidney.