RVC studies offer insights on canine mitral valve repair
Surgical repair is complicated and requires a cardiopulmonary bypass.
Researchers from the Royal Veterinary College (RVC) have uncovered new insights to further understanding of mitral valve repair in dogs.
Across two studies, the new clinical research is expected to lead to better management of surgical risks, as well as helping veterinary teams set owners’ expectations.
Myxomatous (degenerative) mitral valve disease is the most common heart disease in dogs. The condition can cause the mitral valve to deteriorate, leading to valve incompetence and resulting in heart enlargement and, eventually, heart failure.
While surgical repair is often used to treat advanced cases, it is complicated and requires a cardiopulmonary bypass.
With limited research into this procedure, the clinical team at the RVC, which developed open heart surgery in the UK, set out to address this gap with data analysis. In both studies, researchers examined anonymised clinical data from dogs from the UK, Europe and the USA which were undergoing mitral valve repair at the Queen Mother Hospital for Animals at the RVC.
In one study, researchers examined the anaesthetic management and outcomes of 176 dogs undergoing the procedure. They primarily focused on any complications during and around the time of anaesthesia.
For the second study, records from 66 dogs were examined to identify any features from heart scans that could predict whether the heart would stay enlarged during the surgery.
While mitral valve repair was found to be effective, findings highlighted significant intraoperative and postoperative risks that would require management. The research also showed that the most beneficial changes to heart size, known as reverse remodelling, occurred within the first three months of the procedure.
Among researchers’ other findings included the increased risk associated with a longer cardiopulmonary bypass duration. This suggests that time spent on bypass should be minimised if possible.
The study has further highlighted the importance of close perioperative monitoring and rapid-response protocols. Researchers say such protocols are essential for managing anticipated complications.
Statistics revealed that dogs with pre-surgical heart enlargement and a higher body weight were more likely to have persistent left heart enlargement after surgery.
In regards to owner expectations, it was concluded that recovery outcomes from the procedure varied. Researchers say that, when advising owners, veterinary professionals should consider individual patient factors.
Prof Dan Brockman, Professor in Small Animal Surgery and Director of the Cardiothoracic Surgery Service at the RVC, said: “Establishing and maintaining open heart surgical capability at the RVC has been both the most challenging and the most rewarding activity of my 36 years as a specialist small animal surgeon.
“Our team are rightly proud of what we have achieved, but we all know that the route to even greater consistency of results lies in the constant process of reflection, refinement and improvement in every aspect of what we do.”
The study into anaesthetic management and peri-anaesthetic morbidity and mortality can be found here. The study into echocardiographic predictors of persistent left heart enlargement can be found here.
Image © Anna Averianova/Shutterstock
Veterinary practices are being urged to help owners safely dispose of any unused and expired pet medicines - not just antibiotics - during November's Animal Medicines Amnesty. 
