EXPRESS: Inadvertent ligation of pulmonary artery during surgical closure of patent ductus arteriosus in two cats

Case series summary An 8.5-month-old British Shorthair (case 1) and a 2-month-old Domestic Shorthair (case 2) were referred for dyspnoea and lethargy. Echocardiography was compatible with unrestrictive patent ductus arteriosus (PDA) with continuous left-to-right (L-to-R) shunting and concomitant iso-systemic pulmonary hypertension (PH) (case 1), and restrictive PDA with mild PH (case 2). Radiography showed cardiomegaly, increased pulmonary vascular markings, and diffuse interstitial-alveolar pattern consistent with congestive heart failure (CHF) in both cats. Following testing for pulmonary vascular reactivity (case 1) and treatment for acute CHF (case 2), surgical ligation of the PDA was attempted. In case 1, PDA ligation led to severe hypotension and asystole, prompting loosening of the ligature due to suspected intolerance to PDA closure. Cardiac massage was initiated and successfully restored sinus rhythm. The procedure was aborted after partial PDA attenuation. Postoperative echocardiography raised suspicion of pulmonary artery ligation and supra-systemic right ventricle. No surgical revision was performed as the cat remained clinically stable; however, she died 10 days post-surgery. In case 2, severe bradycardia developed 20 minutes after duct ligation followed by cardiorespiratory arrest unresponsive to resuscitation. Anatomopathological examination revealed main pulmonary artery and PDA ligation (case 1), and complete left pulmonary artery (LPA) ligation (case 2). Relevance and novel information Inadvertent ligation of pulmonary artery has been reported in human medicine, and to the best of authors’ knowledge, this is the first report in cats. Prompt recognition and correction of such errors are critical for a favorable immediate perioperative outcome and improved long-term prognosis.