Interventional cardiology is a branch of cardiology that deals specifically with the catheter-based treatment of structural heart diseases. Interventional cardiology techniques have revolutionised our ability to treat specific cardiac diseases avoiding open surgery which might be associated with more complications. These include treating patients with patent ductus arteriosus, pulmonic stenosis and arrhythmias.
The majority of these procedures are performed under fluoroscopy guidance (dynamic X-ray machine) and will require an angiography study (technique used to visualize the inside of blood vessels with particular interest in the arteries, veins and the heart chambers). This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel or inside the heart.
Pacemaker implantation for bradyarrhythmias (abnormally low heart rate) such as high grade atrioventricular block, atrial standstill and sick sinus syndrome has become a routine interventional procedure and leads to the patient then going on to have a normal active life. The procedure is performed via 2 small incisions on the neck with the pacemaker lead being inserted into the jugular vein and advanced to the bottom of the right ventricle. The actual pacemaker is implanted under the skin on the neck. The pacemaker continuously monitors the heartbeat and delivers electrical energy to pace the heart if it’s beating too slowly. The pacemaker can be programmed to suit the needs of the patient.
Balloon Valvuloplasty is performed in patients where moderate/severe pulmonic stenosis is diagnosed. It is performed accessing the heart via the jugular vein where catheters and guidewires are used to advance through the right atrium and ventricle to the stenotic valve. Once the angiography has been performed and the valve measured an appropriate sized balloon catheter is selected. This is then inserted to the level of the pulmonic valve and rapidly inflated and deflated multiple times to widen the stenosis. Great care needs to be taken at this time as inflating the balloon completely blocks the flow of blood out of the heart to the lungs.
Some dogs (especially brachycephalic breeds) might need a coronary angiography prior to this procedure to make sure coronary anomalies are not present.
In patent ductus arteriosus (PDA) the vessel (ductus arteriosus) which connects the aorta and pulmonary artery during the foetal life fails to close after birth. Interventional closure of the duct can be achieved with a canine specifically designed device made of a nitinol mesh (Amplatz canine duct occluder ACDO). Access is through the femoral artery and we use catheters and guidewires to advance to the level of the PDA. Once the angiography has been performed and the measurements confirmed the appropriate size of device will be chosen. The Amplatz can then be deployed to occlude from the inside the PDA and prevent flow through it. The device will remain in place for the dog’s life and will be visible on a chest radiograph.