Use of ambrisentan in the management of refractory pulmonary arterial hypertension following occlusion of a bidirectionally shunting patent ductus arteriosus in a dog.

A nine-year-old male intact Pomeranian, previously diagnosed with a patent ductus arteriosus (PDA), presented with a two-day history of anorexia and lethargy. Echocardiography confirmed a bidirectional shunting PDA and pulmonary arterial hypertension (PAH). The patient underwent transcatheter occlusion of the PDA; however, there was subsequent development of right heart failure secondary to persistent PAH postoperatively. Combination medical therapy using ambrisentan, sildenafil, pimobendan and amlodipine resulted in resolution of right-sided congestive heart failure and oxygen dependency. Follow-up echocardiography and thoracic radiographs revealed gradual cardiac reverse remodelling and ultimately a structurally normal heart. At the last follow-up, the patient remained stable without complications associated with ductal occlusion. This case highlights the success of bidirectional ductal occlusion with postoperative use of ambrisentan for management of refractory PAH.