The Ins and Outs of Interventional Cardiology:

Presenter – Alistair Gibson MVB MRCVS, Consultant Veterinary Cardiothoracic Service; Earlswood Veterinary Hospital, Northern Ireland 

As a general practitioner in small animal practice, the chances of performing corrective interventions on cardiac conditions such as pulmonic stenosis are small. However after watching last week’s veterinary webinar covering interventional cardiology, I found learning about these techniques performed by incredibly skilled veterinary cardiologists fascinating.

‘The Webinar Vet’ organised for Alistair Gibson to lead this webinar having started by using minimally invasive catheter based intervention for cardiac conditions in dogs around 25 years ago. This method of treatment has revolutionised the treatment of cardiovascular disease in people and is becoming increasingly utilised in veterinary medicine for the most common congenital cardiac conditions including pulmonic stenosis, sub aortic stenosis and PDAs.

Alistair discussed each of these conditions in much greater detail within the webinar and explained when and what intervention is necessary. For pulmonic stenosis, when to intervene continues to be a topic for much discussion between cardiologists. It is agreed that pulmonic stenosis would be considered mild where pressure gradients are less than 50mmhg and often these cases would be asymptomatic. However pressure gradients more than 80mmhg would be considered severe with the presence of congestive heart failure or even sudden death being expected. So at what point do we intervene – 60,70 or 80mmhg?? Alistair explained that in his opinion there is no right answer, and that it all depends on looking at the patient as a whole and considering the severity of that patient’s clinical signs.

Up to 25 years ago treatment for pulmonic stenosis involved a thoracotomy and surgical correction. Now the treatment of choice is a balloon angioplasty where a balloon is inserted either by the jugular or femoral vein to the area of the pulmonic stenosis and inflated to dilate the stricture.

Sub aortic stenosis is a trickier condition to treat and although balloon angioplasty is an option, it often leads to the lesion being pushed to one side and then dropping down again giving no benefit to the patient.  However with a 70% mortality rate in severe cases in the first three years, a successful method for intervention seems more than necessary. A new technique has been developed recently which involves using a cutting balloon (i.e. a balloon with razor blades) which cuts into the fibrous muscular layer followed by a high pressure balloon to dilate the stricture. Alistair suggests this could be a reasonable option for young dogs with severe sub aortic stenosis suffering a pressure gradient > 80mmhg.

PDAs are another of the most commonly encountered congenital cardiac conditions and Alistair discussed the wonders of the gold standard treatment – the Amplatz Canine Ductal Occluder, a self-expanding device which can be placed via the femoral artery and locked into place within the ductus. Surgical correction also experiences an excellent success rate of 95% in experienced hands but there is an associated 4-10% mortality rate. So when things go wrong they really go wrong. Using the minimally invasive Amplatz ductal occluder helps to minimise the risk that may be associated with performing invasive surgery.

Alistair finalised this veterinary webinar by demonstrating new techniques recently performed in people, some of which could be the future for veterinary cardiology. The percutaneous aortic valve replacement via catheter delivery and the use of a mitraclip to treat mitral valve insufficiency were two of the techniques on offer and anyone with an interest in medicine and cardiology would find it hard not to be impressed and inspired.

The Stethoscope (MRCVS)