What it involves for the patient
Typically, the patient introduces himself to his family doctor reporting of
palpitations. To correlate the symptoms to a specific supraventricular
arrhythmia, an out-patient ECG monitoring may be useful. These
monitoring systems can be worn by the patient for up to a month. If this type of
monitoring does not identify a specific arrhythmia, an implantable monitor may
be inserted surgically, which may continue to record arrhythmias for years.
If a supraventricular arrhythmia is identified, the patient can be referred to a cardiologist and then to a cardiac electrophysiologist. Based on the evaluations carried out, it is necessary to decide whether to proceed with a pharmacological treatment or with ablation. When the patient has to undergo electrophysiology and ablation, he should remain fasting after midnight on the day before surgery, and should refrain from taking drugs that could interfere with tachycardia inducibility during the electrophysiological study.
On the day of surgery, the patient undergoes routine preoperative measures, with the insertion of a venous catheter and, often, a visit by an anesthesiologist. Analgesia protocols may vary from a sedation with maintenance of the level of consciousness to general anesthesia conducted endotracheally. Simple sedation is chosen in cases where a deeper sedation would risk making the arrhythmia quiescent clinically. Deeper sedations may be necessary in cases of complex, protracted ablation interventions in which it is not necessary to induce arrhythmia or it is important to ensure the immobility of the patient during the operation. During the intervention the patient must lie supine for several hours; the duration of the intervention depends on the complexity of the arrhythmia.
Atrioventricular node re-tachycardia ablations tend to be shorter (shorter than 3 hours) compared to atrial fibrillation operations (which can last up to 8 hours). During the operation and after surgery, the patient can complain of low back pain and anxiety. During the administration of the energy used for ablation (this phase occupies a relatively smaller fraction of the total intervention time) the patient may complain of a sensation of pressure on the thorax or a pleuritic pain. At the end of the operation, the catheters are removed, and manual compression at the insertion site is performed to obtain hemostasis. Usually the patient is discharged the day of the operation or the following day. 2-3 days are generally required for a complete recovery; in case of more complex procedures recovery times may be longer.
The most common pathologies in which
the Ablation is performed are:
Atrial tachyarrhythmias
Premature beats
Atrial parasystole
Ectopic atrial tachycardia
Atrial flutter
Focal Atrial Fibrillation
Tachyarrhythmias from junctional re-entry
Joint junctional tachycardia
Junctional non-common tachycardia
Atrioventricular re-entry tachyarrhythmias
Tachycardia in the orthodromic WPW
Tachycardia in WPW antidromica
Tachycardia in occult Kent
Abnormal occult tachycardia (Coumel)
Tachycardia in abnormal fibers (Mahaim)
Ventricular tachycardia
Originating from the outflow tract of the right ventricle (RVOT)
Arrhythmogenic dysplasia (adipose tissue formation eg in the RVOT)
Ectopic tachycardia
Tachycardia caused by ischemia
In particular, ablation is implemented in:
Atrial tachycardia is a relatively rare arrhythmia that is diagnosed in 5-15% of
patients sent to the cardiac electrophysiology laboratory for undergoing a
supraventricular tachycardia ablation; with advancing age, atrial tachycardia is
responsible for a higher percentage of supraventricular tachycardias. Atrial
tachycardia is a focal arrhythmia that may originate in any region of the right
or left atrium. Catheter ablation is reserved for cases of symptomatic atrial
tachycardia refractory to drug therapy, as well as for patients who have
developed cardiomyopathy mediated by tachycardia following prolonged exposure to
high heart rates.
This form represents supraventricular tachycardia for which catheter ablation is
most frequently prescribed; AV nodal reentrant tachycardia (AVNRT), or
atrioventricular nodal reentrant tachycardia, is a type of abnormal fast heart
rhythm. It is a type of supraventricular tachycardia (SVT), meaning that it
originates from a location within the heart above the bundle of His. AV nodal
reentrant tachycardia is the most common regular supraventricular tachycardia. The ratio of women: men is 2: 1. Catheter ablation
is successful in about 96% of cases, with recurrence rates of between 3% and 7%.
The main complication is the atrio-ventricular node block (0.5-1% of cases);
after the operation, cases of palpitations and inappropriate sinus tachycardia
have also been described. Ablation is indicated as the treatment of choice in
most cases of trio-induced tachycardia of the atrioventricular node; other
factors to be considered in the choice of treatment are the patient's usual
lifestyle and the presence of associated medical conditions.
The atrio-ventricular reciprocating tachycardias, a category of supraventricular tachycardias including Wolff-Parkinson-White syndrome, is characterized by the transmission of electrical impulses through one or more extranodal (accessory) pathways.
At the electrocardiogram (ECG) the transmission of the impulse through the accessory path can manifest itself in the form of a slowing down and a "kneading" (delta wave) of the initial part of the QRS complex. Conduction through the accessory path may, however, be present even in the absence of an evident delta wave; in these cases we speak of a "hidden" accessory way. The efficacy of catheter ablation of the accessory pathways is equal, in most studies, to 95% with recurrence rates of approximately 5%. The overall complication rates, the most common of which are complete atrio-ventricular block and cardiac perforation with tamponade, are 2-4%. When they occur in association with symptoms of tachycardia or documented tachycardia, signs of ancillary conduction pathways (ECG delta waves) should prompt the physician to quickly send the patient to a center where they can perform ablation.
Atrial flutter accounts for about 15% of all supraventricular arrhythmias, and occurs in approximately 25-35% of patients with atrial fibrillation. Atrial flutter is typically more symptomatic than atrial fibrillation, as it is more frequently associated with high ventricular rates. The electrical circuit responsible for the most common forms of atrial flutter is anatomically well defined, and can be readily interrupted with an ablation conducted in the vicinity of the junction between the inferior vena cava and the right atrium. The long-term success rates of ablation operations of typical atrial flutter forms are between 88% and 100%; patients undergoing ablation have lower hospitalization rates than patients treated with antiarrhythmic drugs. The complication rates are 2.5 -3.5%, and include complete heart block, cardiac perforation with tamponade, thromboembolic events and myocardial infarction.
Atrial fibrillation is the most common clinically significant cardiac arrhythmia, with an estimated prevalence, in the general population, between 0.4 and 1%. Atrial fibrillation is associated with an increased risk of stroke, heart failure and all-cause mortality. The principles of treatment include adequate anticoagulation (to prevent embolic strokes), ventricular rate control interventions (to prevent symptomatic and pathogenic tachycardias) and, in selected patients. Interventions aimed at controlling heart rhythm (restoration and maintenance of sinus rhythm). In patients with atrial fibrillation, ablation surgery has the goal of obtaining and maintaining sinus rhythm; the operation is carried out at the interface between the pulmonary veins and the left atrium, ie in the anatomical area of critical importance in the initiation and maintenance of the arrhythmia. Patients with the greatest chance of benefiting from ablation are those with normal left atrium size, and with symptomatic current fibrillation refractory to one or more antiarrhythmic drugs. The presence of symptoms is in fact a decisive factor in defining the desirability or otherwise of the ablation attempt; following the intervention, the evaluation scores of the quality of life show an improvement. Ablation is indicated, as an alternative to drug therapy, to prevent recurrent atrial fibrillation in patients with minimal or no enlargement of the left atrium. A recent meta-analysis has shown that, after the failure of antiarrhythmic drug therapy, radiofrequency ablation is more effective in maintaining sinus rhythm than a treatment that simply involves the continuation of treatment with antiarrhythmic drugs. Paroxysmal atrial fibrillation is in fact characterized by rates of elimination of the arrhythmia, one year after surgery, higher (about 5-80%) compared to persistent atrial fibrillation 160-70%); repeated ablations of atrial fibrillation are associated with higher rates of efficacy. The differences in the success rates of the intervention may depend on the fact that the greater the time of presence of atrial fibrillation, the more the left atrium presents histological changes that may favor or perpetuate the arrhythmia. The risk of serious complications is approximately 6%.