What is catheter ablation of atrial fibrillation?
It has been shown that at least about 95% of paroxysmal atrial fibrillation is closely related to the pulmonary veins of the left atrium. Typically humans have four pulmonary veins that converge from the posterior aspect of the left atrium of the heart; a few patients can have more or less than four. Catheterized radiofrequency ablation is performed by delivering a radiofrequency ablation catheter with a diameter (similar to that of an ordinary ballpoint pencil) through the peripheral venous vessels into the left atrium. High frequency electromagnetic waves, or radiofrequency energy, are delivered at the site where the atrium joins the pulmonary veins and ablate along the opening of the pulmonary veins for one week, generating heat that raises the temperature of the surrounding atrial muscle tissue (usually no more than 40°C), forming a circular scar that will cause atrial fibrillation The abnormal excitation of the pulmonary vein that causes AF is blocked in the pulmonary vein so that it cannot be transmitted to the left atrium, thus achieving the goal of atrial fibrillation eradication. In persistent atrial fibrillation, the ablation procedure is more complex, but is confined to the atria.
Radiofrequency ablation of atrial fibrillation is an interventional procedure that is minimally invasive, with only two puncture points in the right and left femoral veins (root of the thigh). The procedure is performed under local anesthesia and the patient is awake throughout the procedure. Most patients may have a slight burning sensation during the ablation, but it is mostly tolerable. After the procedure, patients need to lie down for 12 hours and can get out of bed and be observed for 1 day. Patients with no recurrence and no complications can be discharged.
Which patients are suitable for catheter ablation
(1) Atrial fibrillation that are more suitable for radiofrequency ablation are
① Patients with atrial fibrillation without underlying heart disease, so-called isolated atrial fibrillation or idiopathic atrial fibrillation;
(2) Patients with well-controlled hypertension combined with atrial fibrillation;
(iii) Patients with atrial fibrillation after thyroid abnormalities have been controlled (better after 6 months of control). The above-mentioned part of patients with mild underlying heart disease, relatively speaking, atrial fibrillation may bring greater harm, and the implementation of radiofrequency ablation has low risk and high benefit, so it is recommended that radiofrequency ablation is preferred for these types of patients.
(2) Indications for which radiofrequency ablation can be performed.
(1) Atrial fibrillation in combination with coronary artery disease, after adequate anti-myocardial ischemic treatment.
(ii) Patients with atrial fibrillation combined with hypertrophic cardiomyopathy.
③ atrial fibrillation after valve replacement for rheumatic valve disease.
(iv) Patients with heart failure combined with atrial fibrillation; these patients have more severe heart disease combined with high surgical risk, but atrial fibrillation poses a greater risk of hemodynamic disturbances for these patients, and considering that atrial fibrillation may bring great benefit to patients after correction, it is also used as an indication for radiofrequency ablation in experienced atrial fibrillation centers.
Risks of atrial fibrillation catheter ablation
Overall, radiofrequency ablation of atrial fibrillation catheters is a relatively safe procedure. However, as with other invasive operations, there are risks associated with AF radiofrequency ablation, and the most serious complications include.
1, pericardial tamponade: that is, perforation of the atrium during the procedure. This complication, although dangerous, can be lifted by pericardial puncture and drainage or surgical hemostasis.
2, cerebral infarction: the main reason is that there is a thrombus in the atrium of the patient before surgery, or the thrombus is formed because the mechanical contraction function of the atrium has not fully recovered after surgery. The incidence of this complication can be reduced by strict and careful preoperative transesophageal echocardiography and perioperative anticoagulation.
3. Left atrial-esophageal fistula: This complication has a high mortality rate once it occurs, but in experienced centers, the incidence of this complication is low. All the above 3 complications can be reduced by some precautions and the patient mortality can be reduced by remedial measures.
Success rates of atrial fibrillation catheter ablation and factors affecting success rates
The success rate of a single radiofrequency ablation procedure is approximately 70% in patients with paroxysmal atrial fibrillation, 60% in patients with persistent or persistent atrial fibrillation, and up to 90% cumulatively after a second or third procedure. The anatomical morphology of the patient’s heart will affect the smoothness of the surgical operation and is related to the success rate of the procedure. Several clinical factors also influence the success rate, such as age, duration of disease, type of atrial fibrillation, left atrial size, hypertension, sleep apnea, and obesity. The experience of the operator also has a relationship with the success rate.
Evaluation of the success of radiofrequency ablation of atrial fibrillation
Treatment success: It is defined as the absence of atrial fibrillation, atrial flutter or atrial tachycardia episodes without the use of drugs for atrial fibrillation 3 months after the procedure. If antiarrhythmic drugs are used after the procedure, the judgment time should be after 5 half-lives of antiarrhythmic drugs or after 3 months of amiodarone discontinuation. Effective treatment: It refers to the absence of atrial fibrillation, atrial flutter or atrial tachycardia after ablation with the use of preoperative antiarrhythmic drugs that are ineffective; or the number of atrial fibrillation episodes is significantly reduced or the duration is significantly shortened after ablation. Early recurrence: Atrial fibrillation/atrial flutter/atrial tachycardia occurring within 3 months after ablation, if the duration is ≥30s, is considered as early recurrence. It was observed that about 60% of early recurrences would disappear on their own. Late recurrence: Atrial fibrillation/atrial flutter/atrial tachycardia occurring 3 months after ablation, if the duration is ≥30 s, are considered as late recurrence. Some people define recurrence after 12 months of ablation as more distant recurrence.
Follow-up to catheter ablation of atrial fibrillation
In the first 3 months after radiofrequency ablation of atrial fibrillation, the mechanical contraction of the atria cannot be fully restored immediately due to the presence of atrial myocardial stenosis, so warfarin anticoagulation is usually required for 3 months after the procedure to prevent thrombosis. The INR should be reviewed regularly and the dose adjusted. In addition, patients need to be monitored for episodes of atrial fibrillation. If symptoms of panic occur, an electrocardiogram should be done at any time. If there are no symptoms, an ECG and 24-hour ambulatory ECG need to be repeated every month to ensure that there are no asymptomatic episodes of atrial fibrillation. An echocardiogram is required 3 months after surgery to evaluate whether atrial function has recovered. If you are taking amiodarone after surgery, thyroid function and liver and kidney function need to be reviewed once every two months.
What should I do if I have a recurrence of AF after surgery?
The damage to the atria caused by RF ablation of atrial fibrillation requires a period of time to recover, so there is still a possibility of atrial fibrillation, atrial flutter, atrial tachycardia and other episodes within 3 months after atrial fibrillation ablation, i.e. early recurrence. At this time, atrial flutter or atrial tachycardia is a manifestation of atrial excitation becoming regular after atrial fibrillation catheter ablation modification, so there is no need for special anxiety. As mentioned above, when symptoms of panic occur, the first step is to go for an ECG or a 24-hour Holter test to confirm that the arrhythmia is indeed recurrent. This is because many times it may only be a symptom caused by more premature beats after surgery. If there are no more episodes of atrial fibrillation, atrial flutter, or atrial tachycardia after 3 months, this atrial fibrillation surgery is successful. If AF is still recurrent after 3 months, you may consider another surgery.