Atrioventricular nodal reentrant tachycardia (AVNRT) is a common heart rhythm disorder caused by an extra electrical pathway near the heart’s atrioventricular (AV) node. This pathway acts as a short circuit, causing a rapid heartbeat. The condition is addressed with catheter ablation, a minimally invasive technique that creates a small scar on the heart tissue to block the abnormal electrical signals.
The Ablation Procedure Explained
Preparations for an AVNRT ablation involve fasting for several hours and may require adjustments to current medications. At the hospital, the patient is taken to an electrophysiology (EP) lab, given a sedative for comfort, and the groin area is numbed with a local anesthetic. Thin, flexible tubes called catheters are then inserted through a vein and guided to the heart.
Before ablation, an electrophysiology (EP) study is performed to map the heart’s electrical system. Doctors use the catheters to send tiny electrical impulses that safely trigger the rapid heartbeat. This allows them to pinpoint the exact location of the extra electrical pathway, known as the “slow pathway,” which is responsible for the AVNRT.
With the problematic circuit identified, the ablation proceeds using one of two primary methods. Radiofrequency ablation delivers heat through a catheter tip to create a targeted scar that destroys the abnormal tissue. Cryoablation uses extreme cold to freeze and eliminate the extra pathway, with the choice depending on the patient’s anatomy and physician’s preference.
After the energy is applied, the electrophysiologist will attempt to trigger the arrhythmia again to confirm success. If the tachycardia cannot be induced, the catheters are removed. A nurse or doctor applies firm pressure to the insertion site to prevent bleeding, and a dressing is applied.
Success Rates and Long-Term Efficacy
Catheter ablation for AVNRT is highly effective, with studies showing the procedure successfully eliminates the arrhythmia in over 95% of patients. This high success rate offers a cure by completely removing the electrical short circuit, preventing future episodes. This effectiveness makes it a preferred long-term solution.
The recurrence of AVNRT after a successful ablation is low, with most instances happening within the first year. Long-term follow-up studies demonstrate sustained freedom from the arrhythmia for years after the procedure. This allows the vast majority of patients to return to their normal lives without the worry of sudden tachycardia.
In the infrequent event that AVNRT returns, the ablation can be repeated with a similarly high chance of success. A recurrence is often due to the heart tissue healing in a way that re-establishes the abnormal connection. A second procedure can address this recovered tissue and reinforce the corrective scar.
Potential Risks and Complications
While AVNRT ablation is a safe procedure, it has certain risks. The most frequent issues are related to the catheter insertion site in the groin, including minor bleeding, bruising, or soreness that resolves within a few days.
A more significant, though uncommon, complication is damage to the heart’s normal electrical system. The extra pathway is located very close to the AV node, which is the heart’s natural electrical bridge. There is a small risk, estimated at less than 1%, of damaging the AV node, which could result in a permanently slow heart rate (heart block) requiring a pacemaker.
Other rare complications include blood clots, which could lead to a stroke, or perforation of the heart wall. Medical teams take precautions to minimize these risks, such as using blood-thinning medications and advanced imaging. The decision to proceed with ablation is made after weighing the benefits against these potential risks with a doctor.
Recovery Following the Procedure
The recovery process begins immediately after the procedure. Patients must lie flat for several hours to ensure the puncture site in the groin heals and to prevent bleeding. Most patients stay in the hospital overnight for observation, though some may be discharged the same day.
In the first few days at home, patients are advised to limit physical activity, avoiding strenuous exercise or heavy lifting for at least a week. Most people can return to non-strenuous work within a few days. Driving is also restricted for the first few days.
It is common to experience unusual heartbeats, such as palpitations or skipped beats, during the healing phase. These symptoms are a normal part of the healing process as the scar tissue forms and tend to resolve on their own. The full effect of the ablation is evident after about eight to ten weeks, once healing is complete.
Long-term follow-up involves an appointment with the cardiologist a few months after the procedure to ensure proper healing. Blood-thinning medication may be prescribed for a period as the internal tissue heals. Once fully recovered, most individuals can resume all normal activities without the limitations previously imposed by their arrhythmia.