Supraventricular tachycardia (SVT) is a type of abnormal heart rhythm, or arrhythmia, characterized by a rapid heartbeat that originates in the upper chambers of the heart. While SVT episodes can be unsettling, SVT ablation has emerged as a common and effective treatment. This procedure aims to correct the electrical issues causing the rapid heart rate, offering a path to restoring a regular heart rhythm.
Understanding Supraventricular Tachycardia
Supraventricular tachycardia involves heart rates ranging from 150 to 220 beats per minute, significantly higher than the normal resting rate of 60 to 100 beats per minute. These rapid heartbeats originate above the heart’s lower chambers, specifically within the atria or the atrioventricular (AV) node. Common symptoms include heart palpitations, dizziness, shortness of breath, and chest discomfort. Fatigue and a feeling of faintness can also occur during an episode.
SVT differs from ventricular tachycardia (VT), which originates in the heart’s lower chambers and is more life-threatening. The underlying cause of SVT involves faulty electrical signaling within the heart. This can manifest as an abnormal electrical pathway creating a re-entry circuit, or as an area of heart tissue generating rapid impulses. These electrical malfunctions disrupt the heart’s coordinated pumping action, reducing its efficiency in circulating blood.
Defining SVT Ablation
SVT ablation is a minimally invasive medical procedure designed to treat supraventricular tachycardia. It identifies and eliminates the heart tissue responsible for abnormal electrical signals that cause rapid heart rhythms. By targeting and neutralizing these problematic areas, the procedure helps restore the heart’s natural electrical pathways and a normal, steady beat.
The procedure employs energy types to achieve this correction. Radiofrequency ablation uses heat to create tiny scars, blocking errant electrical signals. Cryoablation uses extreme cold for a similar effect. Both methods aim to disrupt the electrical misfiring without affecting the surrounding healthy heart tissue.
The Ablation Procedure
Before an SVT ablation, patients fast for several hours. Upon arrival at the electrophysiology lab, an intravenous (IV) line is placed, and a sedative is administered to help the patient relax. The area where catheters will be inserted, most commonly the groin, is then cleansed and numbed with a local anesthetic.
Small incisions are made, and thin, flexible catheters are inserted into a blood vessel, usually a vein in the groin. These catheters are guided through the blood vessels and into the heart, with real-time X-ray imaging (fluoroscopy) assisting placement. Once in the heart, electrodes on the catheter tips send and record electrical signals to map the heart’s electrical activity. This mapping, known as an electrophysiology (EP) study, identifies the location of the abnormal electrical pathways or short circuits causing SVT.
Once the problematic area is located, the chosen ablation energy—either radiofrequency (heat) or cryoablation (cold)—is applied to the target tissue. This controlled application of energy creates a small scar, disrupting the faulty electrical signals. Patients may experience mild discomfort or a sensation of their heart racing during the mapping or ablation phase, but additional medication can be provided for comfort. The procedure lasts between two to six hours, depending on the complexity of the specific SVT.
What to Expect After Ablation
Following the SVT ablation procedure, patients are moved to a recovery area for monitoring. Bed rest is required for several hours to minimize the risk of bleeding at the catheter insertion site. Mild soreness, bruising, or discomfort at the insertion site, and occasional mild chest discomfort, are common.
Patients can return home the same day or after an overnight hospital stay, depending on their recovery and the specific type of SVT treated. Patients are advised to limit strenuous activities and heavy lifting for a few days, with a return to normal activities possible within a few days. Low-dose aspirin may be prescribed for several weeks to help prevent blood clot formation.
SVT ablation has a high success rate, ranging from 90% to 95% for most types of SVT, and up to 98% for specific types. While successful, there is a possibility of recurrence, occurring in 2% to 11% of patients. Serious complications are rare, occurring in less than 1% of cases, and may include bleeding or infection at the insertion site, or damage to heart tissue or blood vessels.