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- Unexpected Surgical Complication in Cats: When PDA Closure Accidentally Ligates the Pulmonary Artery
Unexpected Surgical Complication in Cats: When PDA Closure Accidentally Ligates the Pulmonary Artery
Journal of Feline Medicine and Surgery Open Reports 2025
Obi Veterinary Education
March 13, 2026
Altin Cala, Enrico Lo Cicero, Massimiliano Tursi
Background
Patent ductus arteriosus (PDA) is an uncommon congenital cardiac defect in cats but can lead to significant cardiovascular compromise, including pulmonary hypertension and congestive heart failure. Surgical ligation remains a commonly used treatment. While several complications of PDA ligation are known, inadvertent ligation of the pulmonary artery has not previously been reported in cats. This case series describes two feline patients in which pulmonary artery ligation occurred unintentionally during surgical PDA closure, highlighting the clinical consequences and diagnostic indicators of this complication.
Methods
The report presents two clinical cases. Case 1 involved an 8.5-month-old British Shorthair with unrestrictive PDA and iso-systemic pulmonary hypertension. Case 2 involved a 2-month-old domestic shorthair kitten with restrictive PDA and mild pulmonary hypertension. Both cats underwent diagnostic evaluation including echocardiography and thoracic imaging prior to surgical PDA ligation. Case 1 also underwent pulmonary vasoreactivity testing with sildenafil prior to surgery. Surgical closure of the PDA was attempted in both patients, followed by postoperative evaluation and, in the second case, post-mortem examination.
Results
In Case 1, ligation of the ductus caused severe hypotension and asystole during surgery, prompting partial release of the ligature and termination of the procedure. Postoperative echocardiography suggested inadvertent ligation involving the pulmonary artery, resulting in right ventricular pressure overload. The cat remained temporarily stable but died 10 days later; necropsy confirmed ligation of the main pulmonary artery and PDA. In Case 2, cardiac arrest occurred approximately 20 minutes after PDA ligation and was unresponsive to resuscitation. Necropsy revealed complete ligation of the left pulmonary artery. In both cases, imaging and post-mortem findings demonstrated that the pulmonary artery had been mistakenly included in the surgical ligature.
Limitations
The report is limited by its small sample size and case-series design. Additionally, histopathological examination of the lungs was not performed in one case, limiting evaluation of pulmonary vascular pathology. Long-term clinical follow-up data were also unavailable, particularly in the first case prior to death.
Conclusions
Inadvertent pulmonary artery ligation is a rare but severe complication of PDA surgical closure that can occur in feline patients. Clinical indicators such as sudden hypotension, hypoxia, and acute right ventricular dilation should raise suspicion for this error intraoperatively or postoperatively. Prompt recognition and surgical correction may improve immediate outcomes and long-term prognosis.
(a) Right parasternal short-axis view of the heart base at the level of pulmonary arteries optimised for spectral Doppler interrogation of ductal flow, demonstrating continuous left-to-right shunting with a reduced velocity through the patent ductus arteriosus (PDA) (unrestrictive pulsatile flow) before surgery in case 1. (b) Thoracic radiography (right lateral and dorsoventral view) and CT showing severe cardiomegaly, increased pulmonary vascular markings, diffuse interstitial-alveolar pattern and a large tubular PDA without any constrictions at its ends, respectively. Notice the prominent main pulmonary artery and leftward bulge of the aorta in thoracic dorsoventral view (case 1). (c) Right parasternal short-axis view of the heart base at the level of pulmonary arteries optimised for spectral Doppler interrogation of pulmonary artery/ductal flow after surgical closure of the PDA in case 1, demonstrating predominantly continuous flow below the baseline throughout the diastole, resembling a ‘sawtooth’ flow pattern suspicious of pulmonary artery branch stenosis and reversed PDA
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