During a cardiac ablation, a doctor threads thin, flexible tubes called catheters through a blood vessel and up into the heart, then uses heat or cold energy to create tiny scars that block the abnormal electrical signals causing an irregular heartbeat. The entire procedure typically takes two to four hours, and most people go home the same day or the next morning.
Cardiac catheter ablation is the most common type, but ablation is also used to treat heavy menstrual bleeding by destroying the uterine lining. Both follow the same core principle: controlled energy destroys a small area of tissue to solve a larger problem. Here’s what actually happens during each one.
Before the Procedure
Preparation starts the night before. You’ll be asked to stop eating and drinking after midnight. Caffeine should be avoided for at least 24 hours beforehand, since it can affect your heart rhythm and make it harder for the medical team to locate the faulty electrical signals they’re targeting. Your doctor will also review your medications and may ask you to pause blood thinners or other drugs in the days leading up to the procedure.
On the day itself, an IV line is placed for fluids and sedation. Some people receive conscious sedation, meaning they’re awake but relaxed and unlikely to feel pain. Others get general anesthesia and sleep through the entire procedure. The choice depends on the type of arrhythmia being treated and your overall health. Sticky electrode patches are placed on your chest to monitor your heart rhythm throughout.
How the Catheters Reach Your Heart
The team shaves, cleans, and numbs a small area, usually in the groin, though sometimes the arm or neck. A short tube called a sheath is inserted through the skin into a vein or artery to create a stable opening. Through that sheath, the doctor feeds one or more electrode catheters, thin tubes with wires at the tip, into the blood vessel and advances them up into the heart. X-ray imaging (fluoroscopy) provides a live view so the doctor can guide each catheter to the right chamber.
You won’t feel the catheters moving through your blood vessels. Some people notice a mild pressure at the insertion site, but the numbing medication handles most of the discomfort.
Mapping the Heart’s Electrical Activity
Before any tissue is destroyed, the team needs to find exactly where the problem is. The catheters record electrical signals from inside the heart, and a computer uses that data to build a detailed 3D map of the heart chamber. This map assigns colors based on timing: red marks areas where electrical activity arrives earliest, shifting through yellow and green to blue and purple for the latest activity.
For a focal arrhythmia, where a single spot fires abnormally, the earliest activation point (the red zone) is the target. For arrhythmias caused by a looping electrical circuit, interpretation is more complex. The red and purple zones sit right next to each other because the signal circles continuously from “late” back into “early.” In those cases, the team looks for areas where many color shifts appear over a short distance, which reveals zones of slow electrical conduction that sustain the loop. Those slow-conduction corridors become the ablation targets.
Destroying the Problem Tissue
Once the target is identified, the doctor delivers energy through the catheter tip. The two main approaches work in opposite ways.
Radiofrequency (heat) ablation sends an alternating electrical current into the tissue. That current causes ions in the cells to oscillate rapidly, generating frictional heat. The tissue at the catheter tip reaches temperatures above 55°C (131°F), which is enough to create a small, permanent scar. Each application lasts roughly 30 to 60 seconds and affects an area about the size of a pencil eraser. The doctor may need to make several of these tiny burns to complete a line of scar tissue that blocks the faulty signals.
Cryoablation (cold ablation) works by freezing. Argon gas expands inside the catheter tip, cooling it to around negative 160°C. That extreme cold forms ice crystals inside and around cells. Intracellular ice directly ruptures cell membranes, while extracellular ice draws water out of cells through osmotic shifts, dehydrating and killing them. Reliable cell death occurs once tissue drops below negative 20°C to negative 35°C. Cryoablation is commonly used for atrial fibrillation, where a balloon-tipped catheter can freeze the tissue around the pulmonary veins in a single application rather than point by point.
During the process, you might feel warmth, a mild burning, or an aching sensation in your chest. These feelings are normal and usually brief.
How Endometrial Ablation Differs
Endometrial ablation treats the uterus, not the heart, and the goal is to destroy the uterine lining to reduce or stop heavy menstrual bleeding. No catheters travel through blood vessels. Instead, instruments are inserted through the cervix directly into the uterus. Several methods exist:
- Heated balloon: A catheter with a balloon tip is placed inside the uterus. The balloon is filled with fluid and heated, and the hot fluid destroys the lining on contact.
- Radiofrequency mesh: An electrical mesh is inserted into the uterus and expanded to fit the cavity. Radiofrequency energy passes through the mesh to destroy the tissue.
- Hydrothermal: Heated saline is pumped freely into the uterus, circulating to reach the entire lining.
- Cryoablation: A freezing probe is guided by ultrasound to target specific areas of the uterine lining.
- Electrocautery: An electrical current runs through a wire loop or roller ball, which the doctor moves across the lining to destroy it.
Most endometrial ablations take under 10 minutes and are done under local anesthesia or light sedation. Recovery is faster than cardiac ablation, with most women returning to normal activities within a day or two, though cramping and watery discharge can last for several weeks.
Success Rates for Cardiac Ablation
For atrial fibrillation, the most common arrhythmia treated with ablation, success after a single procedure sits in the range of 50% to 75% at one year. A recent randomized trial found that 76% of patients who combined ablation with structured lifestyle changes (weight management, exercise, reduced alcohol) remained free of atrial fibrillation at 12 months, compared to 53% of those who had ablation alone. Between 16% and 20% of patients need a second procedure within the first year.
Success rates are higher for simpler arrhythmias. Conditions like supraventricular tachycardia (SVT) or atrial flutter often have first-procedure success rates above 90%.
Risks and Complications
Cardiac ablation is considered low-risk, but it is an invasive procedure inside the heart. Serious complications, including stroke, a puncture of the heart wall (cardiac tamponade), and permanent nerve injury affecting the diaphragm, occur in roughly 1.9% to 2.4% of procedures. Minor complications like bruising or soreness at the catheter insertion site are more common and resolve on their own.
Recovery Timeline
After the catheters are removed, firm pressure is applied to the insertion site for 15 to 30 minutes to prevent bleeding. You’ll lie flat for several hours while the site seals. Most people feel tired and may notice some chest discomfort, skipped beats, or mild soreness in the groin for a few days. Irregular heartbeats in the first weeks after ablation are common and don’t necessarily mean the procedure failed. The heart needs time for the new scar tissue to mature.
For the first 48 hours, avoid driving. Most people with desk jobs return to work within two to three days, though physically demanding work may require a longer break. For the first full week, avoid exercise, sexual activity, and lifting anything heavier than 10 pounds (roughly a gallon of milk). After that week, most restrictions are lifted gradually, and normal activity resumes within two to three weeks.