What Is Cardiac Ablation?

Cardiac ablation is a minimally invasive procedure that treats arrhythmias (abnormal heart rhythms) by destroying or isolating the small areas of heart tissue responsible for generating or sustaining the abnormal electrical signals. Using catheters advanced through blood vessels to the heart, electrophysiologists deliver energy to precisely targeted tissue, creating small scars that interrupt the faulty electrical pathways. Cardiac ablation is now the preferred treatment for many arrhythmias, offering the possibility of cure — or at minimum substantial symptom reduction — in conditions that would otherwise require lifelong medication.

The Principle Behind Cardiac Ablation

Many arrhythmias arise from specific, localizable problems in the heart's electrical circuitry:

• Abnormal automatic cells firing at inappropriate rates
• Reentrant circuits — loops where an electrical impulse circles continuously, perpetuating a tachycardia
• Trigger sites generating premature beats that initiate arrhythmias

If the specific tissue responsible for the arrhythmia can be identified and eliminated, the arrhythmia can be permanently cured (or substantially reduced). Ablation creates small scars that are electrically inactive — breaking reentrant circuits or eliminating ectopic foci.

The Electrophysiology Study (Eps): Mapping The Arrhythmia

Before ablation, an electrophysiology study (EPS) is performed to map the arrhythmia — determine its mechanism and precise location. Using multiple catheters placed in the heart chambers under fluoroscopic guidance, the electrophysiologist can:

• Induce the arrhythmia (provoke it so it can be studied)
• Map its origin and circuit using 3D electroanatomic mapping systems (CARTO, EnSite Precision) that create real-time 3D maps of the heart's electrical activation
• Identify the precise target for ablation

Modern 3D mapping has transformed ablation by allowing precise navigation without relying solely on X-ray, reducing radiation exposure and dramatically improving ablation accuracy.

Ablation Energy Sources

Radiofrequency (Rf) Ablation

The most widely used energy source. Radiofrequency current (similar to microwave energy) heats the catheter tip to approximately 50–60°C, creating a small, controlled zone of thermal necrosis (typically 3–6 mm in diameter and 2–5 mm deep) at the contact point. The lesion is permanent — scar tissue replaces the normal cells, permanently interrupting conduction through that area.

Modern RF catheters use contact force sensing (measuring how firmly the catheter presses against the tissue) and irrigated tips (cooling the catheter surface to allow higher energy delivery with better lesion depth). These advances have improved the consistency and effectiveness of RF ablation.

Cryoablation

Uses a refrigerant to cool the catheter tip to −60 to −80°C, freezing and destroying tissue. A key advantage: cryomapping — at moderately cold temperatures (−20 to −30°C), the tissue effect is temporarily reversible; the electrophysiologist can test whether the target site is correct before committing to full cryoablation. This is particularly important near critical structures like the AV node.

Cryoablation is the preferred technique for some arrhythmias (AV nodal reentrant tachycardia — AVNRT) and is widely used in AFib ablation via the cryoballoon.

Pulsed Field Ablation (Pfa)

The newest ablation technology. Pulsed field ablation uses ultra-rapid, high-voltage electrical pulses to destroy cells through irreversible electroporation — disrupting cell membranes without heat. A key advantage: selectivity — cardiac muscle cells are destroyed at lower field strengths than esophageal, phrenic nerve, or pulmonary vein tissue, potentially reducing the risk of collateral damage during AFib ablation. PFA is now increasingly used for AFib ablation and is showing excellent safety and efficacy in early trials.

Conditions Treated With Cardiac Ablation

ATRIAL FIBRILLATION (AFib) — PULMONARY VEIN ISOLATION

The most common ablation procedure. Discussed in depth in Article 170. Pulmonary vein isolation creates scar tissue around the pulmonary vein openings, electrically isolating the most common AFib trigger sites from the rest of the left atrium.

SUPRAVENTRICULAR TACHYCARDIAS (SVTs)

Multiple arrhythmias causing rapid, regular heart rhythms from above the ventricles:

AV Nodal Reentrant Tachycardia (AVNRT): The most common SVT. A reentrant circuit using dual pathways in the AV node region. Ablation of the slow pathway of the AV node — which forms part of the reentrant circuit — cures AVNRT in > 95% of cases with very low risk (< 1%) of AV block requiring pacemaker.

Accessory Pathway (WPW — Wolff-Parkinson-White syndrome): An abnormal electrical connection between atria and ventricles (the "bypass tract") allows rapid reciprocating tachycardia and, in some patients, dangerous rapid conduction during AFib. Ablation of the accessory pathway is curative in > 95% of cases.

Focal Atrial Tachycardia: A single ectopic site firing rapidly in the atria. Ablation of the focus is usually curative.

Atrial Flutter

A macro-reentrant circuit — usually traveling around the tricuspid valve annulus. A single line of ablation across the cavotricuspid isthmus (the tissue between the tricuspid valve and the inferior vena cava) interrupts the circuit, curing typical atrial flutter in > 95% of cases.

Ventricular Tachycardia (Vt) Ablation

VT ablation is more complex — targeting reentrant circuits in scarred ventricular myocardium (post-infarction VT) or abnormal substrates (ARVC, idiopathic VT). Used for patients with recurrent ICD shocks from VT not controlled by medications.

Risks Of Cardiac Ablation

Ablation risks vary by arrhythmia type and complexity. Common risks include:

• Vascular access complications (bruising, hematoma at access site)
• Cardiac tamponade (blood around the heart — treated with pericardiocentesis)
• Stroke or TIA (rare — catheter manipulation in the left heart)
• AV block requiring pacemaker (particularly in AVNRT ablation near the AV node — risk < 1%)
• Pulmonary vein stenosis (AFib ablation — risk < 1% with current techniques)
• Atrial-esophageal fistula (rare but serious complication of AFib ablation)
• Phrenic nerve injury