Clinical Connections  –  Spring 2016

Open heart surgery to treat a stenotic tricuspid valve has been carried out at the Royal Veterinary College (RVC). It is the first reported case of such a procedure being successfully performed on a dog.

Three-year-old Labrador, Mabel, had congenital tricuspid dysplasia. One of Mabel’s main symptoms had been increasing fatigue after exercise and she had been struggling to keep up with other dogs in her family. After developing heart failure, fluid had built up in her abdomen but the referring vets had managed this medically and there was no fluid in her abdomen when she arrived at the RVC.

Mabel, was referred to cardiology specialists at RVC Small Animal Referrals by Jill Todd of Scarsdale Vets who is an RCVS Cardiology Certificate holder. The tricuspid valve was found to be completely fused in the middle, with just two very small holes for her blood to flow through. The operation has completely relieved the stenosis. Since the surgery, in February, Mabel’s energy levels have markedly increased.

Surgery was carried out by Professor of Small Animal Surgery Dan Brockman, assisted by a large team of RVC specialists to provide complete pre and post-operative care. Members of the Cardiology Service investigating Mabel’s condition included Professor of Veterinary Cardiology Virginia Luis Fuentes and veterinary specialist-in-training Dr Rosie Payne.

The surgical team comprised a perfusionist, a senior anaesthetist, an anaesthesia veterinary specialist-in-training and an anaesthesia nurse, two surgery nurses, three surgeons and a cardiology veterinary specialist-in-training. After surgery, Professor Brockman stayed involved in Mabel’s care but the emergency and critical care (ECC) team and the Cardiology Service took the reins, with up to four senior ECC clinicians, a number of veterinary specialists-in-training and half a dozen highly trained ECC technicians working in shifts to care for her.

Professor Dan Brockman with Mabel, the first dog in the world to successfully have treat a stenotic tricuspid valve treated by surgery

Professor Brockman performed the first open heart surgery at the RVC in 2005 and has worked alongside human cardiac surgeons and other veterinarians to develop his expertise.

The RVC team has also collaborated with international colleagues in developing this procedure, including a team from the University of Colorado and veterinary surgeons in Japan. Professor Brockman has also been working with Austrian vet Dr Peter Modler to develop surgical solutions to heart valve problems. Dr Modler who is affiliated with the University of Veterinary Medicine, Vienna, attended Mabel’s operation.

Professor Brockman said: “Because so few veterinary open heart surgery programmes exist around the world, there is a wonderfully collaborative approach by those interested in surgical solutions to heart disease. So, when successful techniques are discovered and developed, they are shared freely in the hope that these can be used by others to improve the health and welfare of animals around the world.”

Commenting on why the RVC team decided to perform this procedure at this point, and on Mabel, Professor Brockman also said: “Lots of things fed into this decision. First and foremost, we had a patient whose pathology made surgery the best solution. I explained to the owner and was very honest that this procedure would be really breaking new ground. Based on what the human paediatric cardiac surgeons will do, and our limited experience of balloon-valvuloplasty suggests this is the best approach for these dogs.”

He added: “The owner has to be prepared to accept the risk and I talk to owners about the risks of open heart surgery. The operation itself is risky, much worse them most other operations. In our hands, for this type of disease, we have about an 80% chance of getting them through the procedure. The owner has to gamble what life the dog has left against the promise of a more normal quality of life and life-span following the operation.”

The team had the heart open for an hour in order to work on the valve. A short-term risk of going on and off bypass is the fragility of canine blood vessels, because cannulae need to be put into several vessels. There is a danger that a major vessel tears apart.

After surgery, Mabel’s stenosis was resolved and she was found to have a mild to moderate amount of regurgitation into the right atrial chamber. After a few more days of additional monitoring at the RVC Mabel has now returned home.

In relation to Mabel’s prognosis if the surgery had not been undertaken, Professor Luis Fuentes said: “It is likely that the signs of right-sided heart failure would have been more difficult to control. Her ability to exercise would have become less and less, and she would have also been at risk of having abnormal heart rhythms associated with the enlargement of the right atrium. Generally we expect them to develop more signs as the disease progresses. These are difficult cases to manage on a long-term basis with drugs. Her life expectancy would have been substantially reduced.”

She added: “I thought Mabel was a perfect candidate to have the procedure as Dan has a lot of experience replacing tricuspid valves in dogs with tricuspid dysplasia. In those cases they are usually leaking, but Mabel’s case was unusual in that she has minimal leaking and she was most affected by the stenosis. That means you may not have to implant any additional valve structure.”

The success of Mabel’s case, along with the presence of leading surgeons, cardiologists, a perfusionist, anaesthesia team and critical care facilities under the same roof, means that the RVC is likely to get referrals from across the UK and continental Europe for other dogs with this condition.

Owner Annabelle Meek, from Melton Mowbray, speaking two weeks after the operation said: "She has just come back in from wandering around the perimeter of my garden for the first time since before the operation. It's more than half an acre and she has been ambling around happily following a scent. I would like to thank absolutely everybody. It's been an enormous team effort on all sides. Every single person I met at the RVC, from the man on the gate to all the hospital staff, was so friendly. After she came home Dan Brockman phoned me every day to see how she was doing. The RVC should be very proud of what they have done for Mabel."

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