Supraventricular Tachycardia (SVT) is a condition where the heart beats abnormally fast, originating from electrical signals in the heart’s upper chambers, or atria. A normal resting heart rate is typically between 60 and 100 beats per minute, but during an SVT episode, the heart rate can suddenly jump to over 150 beats per minute, sometimes reaching up to 220 beats per minute. This rapid rhythm is caused by a fault in the heart’s electrical system, often a looping circuit or an extra, abnormal electrical pathway. Catheter ablation is a common, minimally invasive procedure designed to correct this electrical malfunction, offering a high chance of a cure.
When Catheter Ablation is Recommended
A cardiologist may recommend ablation when a patient’s Supraventricular Tachycardia symptoms are not adequately controlled by medication or when the patient experiences intolerable side effects from antiarrhythmic drugs. While first-line medical therapy often includes beta-blockers or calcium channel blockers, these agents may not fully suppress SVT episodes. Patients who prefer a potentially curative, drug-free solution over long-term medication management are also candidates for this procedure.
Certain specific types of SVT respond exceptionally well to catheter ablation, making it a preferred initial treatment choice. For instance, in conditions like Atrioventricular Nodal Re-entrant Tachycardia (AVNRT), the most common form of SVT, and Wolff-Parkinson-White (WPW) syndrome, success rates for ablation are often greater than 95%. Ablation is also recommended for individuals in high-risk occupations, such as pilots or commercial drivers, where a sudden SVT episode could be dangerous. This procedure often provides a definitive solution to the rhythm disorder.
Preparing for the Ablation Procedure
Preparing for the procedure involves several steps to ensure patient safety and the success of the ablation. Before the scheduled date, patients typically undergo diagnostic tests, including blood work and an electrocardiogram (ECG). It is often necessary to stop taking certain medications, especially blood thinners or antiarrhythmic drugs, for a specific period before the procedure. This reduces the risk of bleeding and allows the abnormal rhythm to be inducible during the mapping process.
Patients are generally required to fast, avoiding eating or drinking anything after midnight the night before the procedure. Upon arrival, an intravenous (IV) line is placed to administer fluids and medications. Arranging for transportation home is also necessary since the sedation administered will prevent the patient from driving after the procedure.
How the Ablation Procedure Works
The procedure takes place in an electrophysiology (EP) lab and begins with the patient receiving a sedative, which may range from light sedation to general anesthesia. Vascular access is gained by inserting thin, flexible tubes called sheaths into a blood vessel, most commonly in the groin area, after the site is numbed. Multiple electrode catheters are then threaded through these sheaths and guided up to the heart chambers using X-ray imaging, called fluoroscopy, for navigation.
Once inside the heart, the procedure enters the mapping phase, known as an electrophysiology study (EPS). Catheters record the heart’s electrical signals to pinpoint the precise location of the faulty electrical circuit or accessory pathway. The physician may use small electrical impulses or medications to intentionally trigger the SVT to accurately map the abnormal pathway. This detailed electrical activation map guides the doctor to the area where the tissue needs to be treated to block the errant signals.
The actual ablation involves delivering energy to the targeted area of heart tissue. There are two primary energy sources used: Radiofrequency (RF) energy and Cryoablation. RF ablation uses high-frequency radiowaves to heat the tissue, creating a tiny scar that eliminates the abnormal electrical signals. Cryoablation uses extreme cold, typically between -60°C and -80°C, to freeze and destroy the problematic tissue.
Cryoablation is sometimes preferred when the target site is located close to the heart’s normal electrical conduction system, such as the AV node. The freezing process allows for “cryomapping,” which temporarily blocks the circuit to test the effects before permanently creating the lesion. The resulting scar tissue permanently interrupts the short circuit that causes the SVT, allowing the heart’s normal pacemaker to regain control. The entire procedure often takes between two to four hours.
Recovery and Long-Term Expectations
Immediately following the procedure, the catheter sheaths are removed, and pressure is applied to the insertion site, usually in the groin, to prevent bleeding. Patients are required to lie flat for several hours to allow the puncture site to seal completely. Most patients can return home the same day or after an overnight stay for observation.
Common temporary symptoms include mild chest discomfort, fatigue, and bruising at the catheter insertion site, which should improve within a few days. Strenuous physical activity and heavy lifting are restricted for about one to two weeks to allow the puncture site to fully heal. Long-term success rates for SVT ablation often exceed 90%, with many patients experiencing a complete cure and no longer needing antiarrhythmic medication.
Patients should understand the “blanking period,” which refers to the first two to three months after the procedure. During this time, temporary recurrences of heart palpitations are common because the heart tissue around the ablation sites is still inflamed and healing. These early recurrences do not necessarily mean the procedure has failed. Follow-up appointments, typically scheduled two to four weeks post-procedure, are important to monitor the heart rhythm and discuss any lingering symptoms.