In a first for South Africa, Dr Adele Greyling, a paediatric cardiologist and electrophysiologist (heart rhythm specialist) at Mediclinic Vergelegen, recently performed innovative, lifesaving cardiac catheter ablation procedure on a seven-year-old boy. This forms part of Mediclinic’s ongoing CSI programme.

When a young patient at a state hospital with a serious heart condition needed specialist treatment, Dr Adele Greyling at Mediclinic Vergelegen was able to help. The seven-year-old was born withtransposition of the great arteries, a heart condition where the great arteries are switched around. “The pulmonary artery comes off the left ventricle instead of the right and the aorta comes off the right ventricle instead of the left,” explains Dr Greyling. “The blood therefore runs in two parallel circuits instead of in series as is normal.”

Oxygen-poor blood therefore flows through the right side of the heart and back to the body without passing through the lungs as it should. Oxygen-rich blood flows through the left side of the heart and directly back into the lungs instead of being pumped to the rest of the body. “Without surgery, patients with this condition would die,” says Dr Greyling.

“To treat transposition of the great arteries,” she continues, “doctors can either do an arterial switch where they switch the great vessels back to their normal positions, or if it’s not possible as in this boy’s case, they do an atrial switch. Here, they put a baffle – a structure that directs blood flow – in the heart, so that now the deoxygenated blood that typically comes from the superior vena cava and the inferior vena cava into the right atrium, goes to the left atrium, or what was the old left atrium, and into the left ventricle and then to the lungs.

“Similarly, the blood that comes from the lungs and goes back into the left atrium, because of that baffle, is now redirected to go to the old right atrium, where it then drains into the right ventricle and goes to the rest of body.” This is known as a Senning procedure. In this boy’s case, the Senning procedure was performed at Steve Biko Academic Hospital in Pretoria. His family later moved to the Western Cape.

Life-threatening atrial flutter

A known complication of this procedure is the development of arrhythmias, specifically atrial flutter. With atrial flutter, the electricity runs in a circle in the upper heart chambers. On occasion, this can conduct very fast to the ventricles, at rates of more than 250 beats per minute. This happened to the patient in question, and he suffered an aborted cardiac arrest.

“He was resuscitated by his family and then brought into the Red Cross War Memorial Children's Hospital because he was in this fast rhythm,” says Dr Greyling. “This could be life threatening because one cannot sustain cardiac output when the heart beats so fast.”

Dr Greyling, who was doing sessions at Red Cross at the time, knew that performing an ablation at Mediclinic Vergelegen offered the boy the best chance of recovery as Red Cross didn’t have the necessary 3D mapping equipment.

The gold standard for the treatment of atrial flutter is an ablation, as it does not respond well to treatment with medication. Ablation is performed by placing catheters in the heart from the groin. The abnormal conduction pathway is then destroyed by heat with what’s known as radiofrequency ablation. In patients with a normal heart, this is an easy procedure to perform.

In patients who’ve had a Senning procedure, the abnormal rhythm often still originates in the old right atrium which is now on the left side of the heart. “If we put the catheter used in the procedure from the groin into the heart, there is no direct access to that chamber,” explains Dr Greyling. “The target for ablation is still the same place. But now there's no connection from the inferior vena cava – which comes from the lower limbs that run into the right atrium – to that chamber.”

That’s why people often think the condition is impossible to treat. “They ask how you can get a catheter to the chamber where you need to ablate to cure the arrhythmia,” says Dr Greyling. “Not many centres in South Africa will attempt this, even in an adult patient. And the patient we treated was only 20kg, which some people would feel is too small for an ablation – even in someone with a structurally normal heart.” As the only electrophysiologist in the country who has paediatric cardiology as a background, Dr Greyling has an advanced awareness of what’s possible when treating such challenging cases – an awareness she aims to spread.

State-private sector partnerships essential

In a South African first, Dr Greyling and her team found a way to cross the baffle to the target chamber and perform the procedure. Although she’s experienced with these baffle punctures and ablation in adult patients with complex congenital heart disease, the youngster was the smallest patient with this condition on whom she’s ever performed an ablation. Though technically challenging, the procedure was ultimately successful.

“We went up through the inferior vena cava into a baffle,” Dr Greyling explains. “Then, in the baffle, we made a puncture with a needle to go through to the old right atrium. Part of the atrial flutter line was ablated in the old right atrium (the usual target for flutter ablation). Part of the line sits on the other side of the atrial baffle in the old left atrium and ablation there was needed to complete the line and achieve block of the flutter line. To do this, we created a 3D electroanatomic map with the specialised mapping system we have in the lab. With this we could localise the catheters and the arrythmia circuit.”

If it wasn't for Mediclinic agreeing to offer the time and assistance in the lab with its equipment, this treatment wouldn’t have been possible, she continues. “Such partnerships, where private health care subsidises or assists in cases where the public sector can't offer the required services are the only way forward.”

In this young patient’s case, medication was not controlling the arrhythmia and could have given rise to complications, which is why the ablation was the best option. “Most of the drugs we use have side-effects so it's not a long-term option,” says Dr Greyling. “You can't keep a seven-year-old on those drugs throughout their life as it can affect their eyes, lungs and thyroid gland. It’s life-changing for this child to be off medication and be back in a normal rhythm.”