Interventional Cardiology
Our facility has been purpose-built to deliver exceptional veterinary cardiology care, equipped with the most advanced technology available
Interventional cardiology refers to a minimally invasive surgery sometimes described as a type of “key-hole” surgery where the heart is accessed via a blood vessel. Special types of x-ray imaging known as fluoroscopy and angiography are used to guide the surgical procedure. When indicated, we also employ transoesophageal echocardiographic (TOE) guidance. This state-of-the-art technique provides real-time, high-resolution images of the heart from within the oesophagus, significantly enhancing procedural accuracy and safety, especially in complex cases.
We provide a variety of minimally invasive procedures to manage numerous heart conditions. The main conditions treated with cardiac interventions include pulmonic stenosis (by balloon or stent valvuloplasty), patent ductus arteriosus, advanced heart failure (by left atrial decompression), and abnormally slow heart rate that require pacemaker implantation.
What is pulmonic stenosis and how is it treated?
Pulmonic stenosis is a type of congenital heart disease (a condition that the animal is born with) that occurs due to an abnormal pulmonic valve (green circle in the illustration).
The abnormal valve results in partial obstruction to the flow of blood and subsequently increases the workload of the right side of the heart. Over time this can lead to reduced ability to exercise, weakness, collapsing episodes and eventually heart failure.
A consultation, physical examination and ultrasound of the heart (echocardiography) is performed initially to assess whether pulmonic stenosis is present, the severity of the condition and whether other heart abnormalities are present that may interfere with surgery. In moderate and severe cases, a balloon valvuloplasty can be performed to help alleviate the obstruction. This procedure involves a special “balloon” catheter which is guided from a vein in the neck into the heart and the narrowed pulmonic valve. The narrowing is highlighted by injecting the contrast dye within the heart, as shown by the yellow arrow in the picture below. Once the catheter is in the correct place the balloon is inflated to stretch the valve and improve blood flow – the waist created on the balloon by the narrow valve can be appreciate at the level of the green arrow on the picture below. The balloon is then removed and scan is performed few weeks after surgery to assess how successful the surgery has been. Patients with pulmonic stenosis might benefit from tablets called beta blockers usually prior to surgery and most patients will remain on this medication after the surgery has been performed.
In some cases where balloon valvuloplasty is not effective or suitable—such as when the valve is severely thickened or dysplastic—a procedure called stent valvuloplasty may be considered instead. This involves placing a stent (a small metal mesh tube, as the one in the picture above – red arrow) in the narrowed area of the pulmonary artery (yellow arrow) to help keep it open and improve blood flow. The stent is delivered using a ballooned-tipped catheter in a similar way to the balloon procedure. While technically more complex, stent placement can provide a longer-lasting improvement in certain patients, compared to balloon dilation alone.
What is a PDA and how is it treated?
Patent Ductus Arteriosus (PDA) is a persistent communication that remains after birth between the aorta and the pulmonary artery (the two major blood vessels that leave the left and right side of the heart respectively). This vessel should close at birth to stop blood being able to flow between the aorta and pulmonary artery but remains open in some animals. This causes an excessive amount of blood to flow into the left-side of the heart and results in the heart becoming severely enlarged. If left untreated, these patients will go on to develop severe heart failure. Many patients with a PDA show no clinical signs other than a loud heart murmur but some will become lethargic, reluctant to exercise and breathless, particularly if heart failure develops.
A thorough consultation, physical examination and echocardiography is done to assess the heart size and function and to definitively diagnose a PDA. The main surgical procedure that is performed involves the placement of a special device within the PDA, known as an Amplatz® Canine Duct Occluder (ACDO - picture below), as well as other smaller devices for smaller dogs and cats.
This is done by passing a catheter into the main artery within the hind leg (the femoral artery) and “plugging” the PDA with the device, stopping the flow of blood across the PDA, as illustrated below on the right.
The images below depict a fluoroscopic study of a dog diagnosed with a patent ductus arteriosus (PDA) undergoing minimally invasive occlusion at our hospital. In the image on the left, the aorta (Ao) is seen communicating with the pulmonary artery (PA), as demonstrated by the contrast dye flowing through the PDA (green arrow). In the image on the right, the contrast dye no
To guide the placement of this device we also use a 3D TOE assessment of the PDA. This advanced imaging technique provides highly detailed, real-time views of the heart and the PDA from inside the oesophagus, allowing for more precise planning and guidance during the procedure. As a result, the intervention is safer and more accurate, improving outcomes for our patients.
A repeat ultrasound scan is performed after surgery to ensure that the PDA has been successfully occluded. The success rates of this type of surgery are excellent if the patient has no signs of heart failure and go on to have a normal overall life expectancy.
Pacemakers
A pacemaker refers to an external electronic device that is used to maintain the heart rate. In dogs and cats, a pacemaker is usually placed when there are abnormally slow heart rates that cause a reduction in the amount of blood flowing around the body resulting in episodes of collapse and fainting. A pacemaker monitors the heartbeat and will stimulate the heart to beat if the heart rate severely drops.
Certain types of pacemaker can also detect periods of exercise and stimulate the heart rate to increase during these periods. This is known as a rate-responsive pacemaker. Most pacemakers are set to have a heart rate range of 60 to 160 beats per minute.
The initial steps in deciding whether or not a pacemaker is required for your pet is to have a consultation including a clinical examination, echocardiography and an ECG (electrocardiography) which assesses the heart’s electrical activity. Other diagnostic tests that may be needed include bloodwork, chest x-rays and a Holter ECG, which is a monitor that is fitted to your pet over a longer period of time to monitor the heart rate and rhythm.
In dogs, the pacemaker itself is surgically placed under the skin at the side of the neck. A pacing lead is inserted into the heart via a catheter through the main blood vessels in the neck (the Jugular vein) and into the right side of the heart. The pacing lead then stays within the heart and is attached to the pacemaker in the neck, allowing it to deliver the electrical “spark” if the pacemaker detects that the heart rate is too slow to ensure the heart continues to beat.
After the pacemaker has been fitted, your pet will need to return regularly (every 6-12 months depending on the case) in order to perform a series of checks on the pacemaker and ascertain that it is working properly.
Interventional cardiology in heart failure
Heart failure in dogs can be caused by various conditions, often advanced myxomatous mitral valve disease and occurs when the heart can no longer pump blood efficiently. As the disease progresses, pressure builds up within the heart—especially in the left atrium—leading to fluid accumulation in the lungs (pulmonary oedema). This makes breathing difficult and significantly reduces a pet’s quality of life. While medications can manage symptoms in many cases, some dogs continue to struggle despite optimal medical therapy. In such situations, additional, more advanced treatment options may be considered.
Left Atrial Decompression (LAD) is a minimally invasive, palliative procedure designed to support dogs and cats with advanced heart disease and congestive heart failure. It is performed using a technique called transeptal puncture—a “beating-heart” procedure that avoids opening the chest or heart. At Sarah Smith Cardiology, we are proud to be among the first veterinary hospitals in the UK to offer this advanced procedure.
Using a thin, flexible catheter, the heart is accessed through a vein in the neck. Under real-time fluoroscopy and TOE guidance, the catheter is carefully advanced from the right atrium to the left atrium, creating a communication between those 2 chambers. This helps relieve the high pressure in the left atrium caused by the underlying heart disease, reducing the amount of fluid in the lungs and improving breathing and comfort.
The picture below is a post-op ultrasound of the heart (echocardiogram) showing the presence of a communication (red flow indicated by the green arrow) shunting from the high-pressure left atrium (LA) into the lower-pressure right atrium (RA) as a result of a successful LAD.
This procedure is especially helpful for pets with ongoing signs of heart failure—such as laboured breathing, lethargy, weight loss, or increased thirst and urination—despite receiving appropriate medical treatment. It may also be considered when administering oral medication is difficult or when concurrent kidney disease limits the safe use of standard heart medications.
The procedure is performed under general anaesthesia through a small incision in the neck and typically takes 1 to 2 hours. Our team provides continuous monitoring to ensure safety and comfort throughout the procedure and recovery. Most pets are able to return home comfortably the same evening, with improvements often noticed soon after.
If your pet has been struggling with heart failure despite treatment, talk to us about whether Left Atrial Decompression could help improve their quality of life.