Why we ablate SVT
Supraventricular tachycardia (SVT) is a sudden, fast, regular heartbeat that starts above the ventricles. Most people describe a heart that “switches on” out of nowhere — pounding, racing, sometimes with lightheadedness or chest pressure — and then switches off just as suddenly. The episodes are usually not dangerous, but they can be disruptive, frightening, and unpredictable.
What makes SVT special is that the underlying problem is almost always a single, small, abnormal electrical circuit. Find that circuit, ablate it, and the arrhythmia is gone. That’s why ablation is so effective here: we are fixing the actual cause, not just suppressing the symptoms with medication.
The two most common types we ablate
AVNRT — atrioventricular nodal reentrant tachycardia
The most common SVT in adults. The AV node — the gatekeeper between the upper and lower chambers — has two electrical pathways running through it: a fast one and a slow one. In most people this doesn’t matter. In some, an extra beat can launch a signal down the slow pathway and back up the fast pathway in a self-sustaining loop, and the heart suddenly races at 150–220 beats per minute.
The cure is to ablate the slow pathway. We map carefully along the floor of the right atrium near the AV node and deliver a small amount of energy to a spot called Koch’s triangle. Because we are working close to the AV node itself, the one specific risk is producing AV block that would require a pacemaker — uncommon (<1%), but the reason we move methodically and watch for warning signs throughout the procedure.
AVRT — atrioventricular reentrant tachycardia (accessory pathway)
Here the abnormal circuit isn’t inside the AV node — it’s an extra electrical wire (an “accessory pathway”) connecting the atria and ventricles outside of the normal conduction system. When the wire is visible on the resting ECG, the pattern is called Wolff-Parkinson-White. The pathway can sit almost anywhere along the ring between the atria and ventricles, on the right or left side of the heart.
We pace and map to locate the precise spot where the pathway crosses, then ablate at that single point. Right-sided pathways are reached straightforwardly from a leg vein. Left-sided pathways require us to cross to the left side of the heart — either across the wall between the atria or backward across the aortic valve — which adds a small amount of additional risk but is routine.
The procedure step by step
You’ll be sedated but breathing on your own; we keep you comfortable rather than deeply asleep so the heart’s own responses to gentle pacing are preserved. After numbing the skin, we place a few thin catheters through veins in the groin (and occasionally the neck). Under X-ray and using 3D electroanatomic mapping, we position them at specific spots inside the heart.
The first task is to prove the mechanism — we pace the heart in carefully designed sequences to trigger the SVT and confirm exactly which circuit is responsible. This is the diagnostic half of the procedure. Once we know the circuit, we ablate at the specific target with either radiofrequency energy (a small precise burn) or cryoablation (freezing). Cryo is sometimes preferred near the AV node because, if early lesions show any sign of trouble, freezing can be reversed before becoming permanent.
After ablation we re-test: we again try to trigger the SVT. If we can’t, we’re done. Total lab time is typically about two hours, with the ablation portion itself usually under thirty minutes.
After the procedure
You’ll lie flat for a few hours while the groin seals, and most patients go home the same day. It’s normal to feel some skipped beats or brief flurries during the first few weeks — this is healing tissue, not failure of the procedure. We see you back at about 4–6 weeks. After a successful SVT ablation, most patients need no rhythm medications, no chronic monitoring, and no further EP follow-up.
When we’d choose another option
If episodes are rare, brief, and well-controlled by vagal maneuvers or an occasional dose of medication, observation is reasonable. Daily medication is an option for patients who would prefer to avoid a procedure. But for anyone with frequent, disruptive, or poorly tolerated episodes — and especially for younger patients facing decades of episodes — ablation is usually the better long-term answer.