Patent ductus arteriosus (PDA) is one of the most common congenital cardiac diseases in dogs. ECG-gated computed tomography angiography (CTA) can be a complementary minimally-invasive way in early planning of interventional occlusion. The aim of this prospective observational study was to report CTA findings associated with PDA.

A total of 25 dogs diagnosed with PDA aged 2 to 54 months and weighing 2.5 to 38.1 kg were enrolled: all dogs were planned to undergo possible interventional occlusion under the same anaesthetic directly after CTA. The contrast medium injection protocol was individually tailored with total injection time equaling the sum of diagnostic scan delay and scan duration. First, 1 ml/kg undiluted contrast medium (370 mgI/ml) was administered for two thirds of the total injection time, directly followed by 2 ml/kg of 1:1 diluted contrast medium for one third of the total injection time. The CT scan was triggered manually under a single breath hold when the contrast bolus reached the descending aorta. Scanning was commenced regardless of the heart rate.

Image reconstruction was performed during mid-diastole (70% of the R-R interval). In 2 dogs the heart rate was too high (>140 BPM) to allow image reconstruction. In the other 23 dogs the sagittal plane of the images was optimized for visualization of the PDA. The minimal ductal diameter at the pulmonary ostium (median 3.4 mm, range 1.7–11.6 mm), ampulla diameter (median 7.0 mm, range 3.7–13.2 mm), ampulla length (median 10.7 mm, range 6.8–18.9 mm), angle between PDA and aorta (median 149 degrees, range 134–155 degrees) and Miller type PDA morphology (type I, n=5; type 2A/B, n=16; type III, n=2) were determined. A total of 23 dogs (all except the 2 dogs with a type III PDA morphology) subsequently underwent successful interventional occlusion, and in all dogs with available CTA images the suspected PDA morphology could be confirmed with fluoroscopy.

In conclusion, despite fluoroscopy remaining the gold standard for accurate sizing of the PDA prior to interventional occlusion, CTA is a complementary diagnostic method that may provide additional relevant information for planning of catheter-based intervention, potentially shorten surgery time and reduce the amount of radiation to which the clinician is subjected.

Disclosures

No disclosures to report.

Niek Beijerink Speaking & Consultancies: Boehringer Ingelheim, Elanco Animal Health, Bova Compounding, CEVA Animal Health, Blackmores. Grants/Research: Luoda Pharma.