Branham sign in dogs undergoing interventional patent ductus arteriosus occlusion or surgical ligation: a retrospective study

Background: The Branham sign is a baroreceptor response that follows patent ductus arteriosus (PDA) closure. Although described in dogs following both interventional and surgical ductal closure, a direct comparison of the Branham sign elicited by these two techniques has not been made. Aim: Since closure with an Amplatz canine ductal occluder (ACDO) occurs over 10 minutes and surgical ligation (SL) is more rapid, we hypothesised that the Branham sign following occlusion of a PDA with an ACDO would be less severe than following SL. Methods: Clinical records of dogs diagnosed with left-to-right shunting PDA between 2008 and 2018 were retrospectively reviewed. Of 139 dogs undergoing PDA occlusion, only 41 dogs (ACDO n = 32, SL n = 9) were included after applying exclusion criteria. Heart rate and BP from occlusion time (T0) until thirty minutes post occlusion (T30) were recorded. Signalment and anaesthetic protocol were also recorded. The influence of age and weight on the haemodynamic variations was assessed. Haemodynamic variables and calculations were compared between and within groups using a repeated measures general linear model, and post hoc tests were applied if significance was identified. Results: A mild Branham sign was present in both groups, and haemodynamic changes were not significantly different between groups. In both groups, there was a significant decrease in HR (11 bpm, 5.3 – 16.3; p < 0.001) (10.4 %, 5.4 – 15.5; p < 0.001) and increase in diastolic BP (9.5 mmHg, 3 – 16; p = 0.002) (23.5 %, 7.1 – 39.9; p = 0.002), but systolic BP did not change significantly (p = 0.824). Age and weight did not influence Branham sign. Conclusion: The Branham sign in dogs is mild in both groups, lasts for at least 30 minutes, and is independent of the method of PDA closure