What Is Thermal Ablation?

Cardiac radiofrequency ablation (catheterradiofrequency ablation) is to send an electrode catheter through a vein or arterial blood vessel to a specific part of the heart cavity, releasing radiofrequency current to cause local endocardial and subendocardial coagulative necrosis, and to block abnormal conduction of rapid arrhythmia Beam and origin point interventional technology. The RF current introduced through the catheter into the heart cavity ranges from 1-3 mm, which will not cause harm to the body. Radiofrequency ablation has become the most effective way to cure paroxysmal tachycardia. The basic equipment includes X-ray machine, radio frequency ablation instrument and intracardiac electrophysiological examination instrument. ^[1]

Liu Qiming

(Chief physician)

Department of Cardiology, Second Xiangya Hospital

Introduction to Radiofrequency Ablation Surgery

Radiofrequency ablation surgery indications

I. Atrioventricular reentrant tachycardia (pre-excitation syndrome): There is a congenital bypass between the atrioventricles, and the radiofrequency of the catheter will cut off the bypass, and tachycardia or pre-excitation will no longer exist.

Atrioventricular node reentrant tachycardia: the atrioventricular node forms a "double path", and the current runs quickly in the reentrant loop formed by the two paths under appropriate conditions, causing tachycardia; the catheter RF ablation slows down and only retains Fast track, tachycardia is no longer ready for seizures.

3. Atrial flutter (atrial flutter): Atrial flutter is a large loop in the atrium, and the current continuously rotates around the loop. The atrial beats 250-350 times / minute, and the ventricle is generally 150 times / minute. The catheter RF can destroy the ring. Circuit, causing a two-way current block, thereby eradicating atrial flutter.

Atrial tachycardia (atrial tachycardia): Atrial tachycardia is an "excitation point" where abnormal current is rapidly issued in a part of the left atrium or right atrium, or there is a small reentrant motion in the atrium; An "excited point" or reentry loop, ablation is performed to get the cure.

V. Premature ventricular contractions (premature beats): mainly used for single-source frequent ventricular premature with obvious clinical symptoms; often caused by ventricular "excitatory foci"; mapping of ectopic excitatory foci ablated, the ventricle can disappear as soon as possible .

Six, ventricular tachycardia (ventricular tachycardia): including idiopathic, bundle branch reentry and scarred ventricular tachycardia. Idiopathic ventricular tachycardia is common in people with normal heart structure and function. There is no evidence of organic heart disease, but frequent episodes of tachycardia can cause tachycardial cardiomyopathy; it occurs in the right or left ventricular outflow tract and the left An "excitatory foci" on the ventricular septum quickly emits current, which causes tachycardia. The excitation foci are found through the catheter, and RF current is released for ablation, and the VT can be cured. Bundle branch reentry ventricular tachycardia and scarred ventricular tachycardia are more common in patients with organic heart disease such as dilated heart disease, coronary heart disease, and congenital heart disease surgery. Patients can experience syncope and convulsions during seizures, often requiring emergency rescue. Bundle branch reentry ventricular tachycardia is the current return loop (turn circle) between the left and right conducting bundle branch and left and right ventricle of the heart, and the catheter electrode finds and emits RF current to block the loop; scarred ventricular tachycardia is Due to the reentry loop generated by the surviving myocardial cells between the heart fibrous scar tissue, the radiofrequency current is issued to block the loop, and tachycardia is also cured. Catheter radiofrequency ablation can cure ventricular tachycardia but cannot cure heart disease; if the ablation is unsuccessful or a ventricular tachycardia is at risk of life, an embedded cardiac defibrillator (ICD) should be implanted to prevent sudden death.

Atrial fibrillation (AF): Atrial fibrillation is the most common persistent arrhythmia. Studies have found that the trigger of atrial fibrillation is due to the rapid electrical impulses issued by the "myocardial sleeve" on the large vein connected to the atrium. Also related to atrial self-remodeling. Catheter electrodes are used to ablate the circumferential pulmonary vein to form the "electrical isolation" of the large veins and the atria, or some linear ablation in the atria can achieve the goal of radical atrial fibrillation. ^[2] ^[3]

Precautions before radiofrequency ablation

1. Electrophysiological examination and radiofrequency ablation generally require hospitalization, and require routine laboratory tests (including electrocardiogram and blood tests, etc.).

Second, dietary precautions: Do not eat or drink 6-8 hours before surgery.

3. Tell the doctor the name and dosage of the medicine used. All antiarrhythmic drugs should be stopped 3-5 days before the electrophysiological examination and radiofrequency ablation. The antiarrhythmic drugs may affect the test results.

4. Tell your doctor about allergies to the drug.

Radiofrequency ablation surgery

Precautions for radiofrequency ablation

Children have the characteristics of thin blood vessels, small heart, etc. The implementation of radiofrequency ablation is difficult and risky, and it needs to be carefully selected. For children with tachyarrhythmia under 3 years of age, try to take medication as much as possible. Radiofrequency ablation surgery can be considered for patients over 3 years of age. For arrhythmias such as premature beats, the drug cannot shorten the course of the disease, but only relieves the symptoms. Drug treatment should be highly vigilant for its toxic and side effects; only when the tachycardia affects the child's quality of life and physical development, anti-arrhythmic drugs are actively used, suitable for the situation Radiofrequency ablation is used.

Radiofrequency ablation procedure

Electrophysiology and radiofrequency ablation are performed in a special operating room (called a catheterization room). Catheter room staff typically includes electrophysiologists, assistants, nurses, and technicians. The patient is lying on the X-ray examination bed. The medical staff will connect various monitoring devices to the patient's body and cover your body with a sterile sheet. The medical staff will wear a sterile surgical gown and gloves.

First the skin of the catheter insertion site (inguinal, arm, shoulder or neck) is disinfected, and local anesthesia is used for local anesthesia; then the vein / arterial blood vessel is punctured with a puncture needle, and the electrophysiological examination catheter is inserted into the heart cavity through the blood vessel; The electrode catheter is a long, bendable catheter that can carry electrical signals to and from the heart. The electrode catheter records the electrical activity of different parts of the heart and issues weak electrical stimuli to stimulate the heart in order to induce arrhythmia and clear the diagnosis of tachycardia; then the doctor finds the exact part of the heart's abnormal electrical activity through the catheter (this process is called "standard Measurement "), and then send RF current ablation treatment through the ablation device, so as to cure tachycardia.

Patient experience with radiofrequency ablation

The patient is generally awake during the whole process. Sometimes the doctor will use sedatives to relieve the tension of the patient, and the patient will monitor the whole process. The electrophysiological examination generally does not cause pain, and the patient will not feel when the catheter is in the blood vessel and the heart cavity. The doctor may The heart will be stimulated with a weak current. The patient will not feel these electrical pulses, which will often induce tachycardia. It will feel the same as before (he may have dizziness, dizziness, palpitations, chest pain, or shortness of breath, etc.). Tell the doctor. ; These operations are relatively low risk and relatively safe.

Radiofrequency ablation success rate

Atrial arrhythmias such as atrioventricular node reentrant tachycardia, pre-excitation syndrome and other arrhythmias can achieve a success rate of more than 98%, while atrial tachycardia, atrial flutter, early ventricular, idiopathic ventricular tachycardia and other complex arrhythmias can achieve successful rates More than 90%, the current ablation success rate of atrial fibrillation is 80 to 90% for paroxysmal atrial fibrillation, and 60 to 80% for persistent and chronic atrial fibrillation. The success rate of reablation will be further improved.

Radiofrequency ablation surgery complications

Complications of vascular puncture include local bleeding, hematoma, infection, pneumothorax, thrombosis, embolism, etc. Complications of catheter operation include aortic valve regurgitation, myocardial perforation, pericardial tamponade, etc. Complications of discharge ablation include atrioventricular block, myocardium Infarction, etc. ^[2] ^[3]

Precautions after radiofrequency ablation

After radiofrequency ablation, the patient must stay in bed and rest according to the doctor's advice. The sandbag at the venipuncture point is compressed for 6 hours, the sandbag at the arterial puncture area is compressed for 8-12 hours, and the affected limb is braked (restricted). Watch for bleeding.

Give a digestible diet while in bed;

Closely observe the heart rate and heart rhythm at the early stage after radiofrequency ablation, and report it to the doctor if uncomfortable, and check the ECG, echocardiogram and chest radiograph if necessary;

If the feeling of tachycardia recurs after the operation, but it does not really happen, you don't need to be nervous and don't need special treatment;

Normal activity can resume after 1 week;

If there is a relapse after discharge, the nearest ECG should be recorded in time, and the surgeon should be contacted to determine the next treatment plan.

Anticoagulant therapy is required after radiofrequency ablation, and anticoagulant drugs are generally required for 1-3 months, depending on the patient's heart rhythm, age, and general conditions. The application of other auxiliary drugs is mainly the use of amiodarone after atrial fibrillation ablation, which can be taken in accordance with the doctor's order to achieve the desired effect.