Cardiac ablation

Generality

Cardiac ablation, or catheter ablation, is a therapeutic treatment reserved for people suffering from cardiac arrhythmias. By cardiac arrhythmia, any alteration of the normal heart rhythm is meant.

Cardiac ablation is not always a first choice intervention; however, in some certain circumstances it becomes fundamental and represents an excellent solution to arrhythmic disorder.

Prior to treatment, no special preparation is required, except for some clinical findings and some recommendations, such as for example a full fast for at least 6-8 hours.

The risks associated with the procedure are different and should not be overlooked.

The achievable results are more than good, however, for the best benefits you need to adopt a healthy lifestyle.

What is cardiac ablation

Cardiac ablation is a moderately invasive medical procedure practiced to correct heart rhythm abnormalities. These abnormalities are the so-called cardiac arrhythmias, while the normal heart rhythm is also called sinus rhythm .

Performed by a cardiologist specialized in electrophysiology, cardiac ablation involves the use of a very particular catheter, which is inserted into the body through the femoral vein (in the upper part of the thigh) or the jugular one (in the neck), and from there conducted at the heart, where it will be put into operation.

The goal of cardiac ablation is to eliminate the cause of the arrhythmia; not surprisingly, ablation derives from a Latin verb ( auferre ), which means "to take away".

WHAT ARE THE SINUS RHYTHM AND THE HEART ARITHMIES

Sinus rhythm is the normal heart rhythm. The term sinus derives from the fact that the normal heart rate is regulated by the so-called atrial sinus node . Located at the level of the right atrium, the atrial sinus node is a center for generating electrical impulses, which contract the heart and scan the right heart rate .

Figure: surrounded by a red box, the centers generating the electrical impulses. The atrial sinus node is the main one and the one from which the heart rhythm must depend; the atrium ventricular node, the atrium ventricular bundle (or bundle of His) and the Purkinje fibers, on the other hand, are the so-called secondary centers, which are directed by the principal, but which at the same time cooperate with it in a decisive way.

This generator center does not operate alone, but in collaboration with other similar centers (secondary centers), which, however, must comply with its directives, if they want to work at their best.

Cardiac arrhythmias are alterations of sinus rhythm. The alterations are not all the same, but they can cause:

A change in heart rate. The heart rate can become faster or slower than the normal threshold (which is between 60 and 100 beats per minute).
A variation of the center for generating electrical impulses. In other words, it is no longer the atrial sinus node that directs the heart rhythm.
Disturbances to the propagation of electrical impulses. Also called conduction disorders, these anomalies disrupt the normal sinus rhythm.

When practicing cardiac ablation

Among the various treatments for the treatment of arrhythmias, there is also cardiac ablation. It is usually never the first therapeutic option, but it can become so if:

Pharmacological treatments for cardiac rhythm abnormalities (ie, antiarrhythmics ) have had no success.
Antiarrhythmic drugs have caused side effects, worsening the pathological situation, rather than improving it.
Current arrhythmias are particularly suitable for treatment by cardiac ablation. For example, a condition like Wolff-Parkinson-White syndrome causes cardiac rhythm abnormalities that lend themselves very well to cardiac ablation treatment.
The patient is at risk of complications, such as cardiac arrest.

Preparation

Before proceeding with cardiac ablation, the patient must meet with the operating cardiologist to know the characteristics of the operation (risks, pre-operative measures, procedure, recovery phase, etc.) and to undergo clinical examinations and tests.

PRE-OPERATOR CLINICAL EXAMINATIONS

The various pre-operative clinical tests consist of an assessment of the heart's health and an analysis of the patient's history, both recent and past. Their informative contribution is fundamental, since it is from them that the possible contraindications to the cardiac ablation intervention emerge.

In particular, as far as the clinical history is concerned, it is important for the doctor to know if the patient suffers or has suffered in the past from serious pathologies (cardiac and not only), if he has a pacemaker in the heart or an implantable defibrillator or if you take any kind of drugs.

PRE-OPERATIVE MEASURES

In order for everything to work out for the best, it is imperative that the patient, before cardiac ablation, adheres to the following precautions:

It appears, on the day of the intervention, to fast for at least 6-8 hours.
Stop any drug treatment aimed at treating heart rhythm disorders (antiarrhythmic therapy). Otherwise, in fact, there is the danger of not getting the benefits hoped for.
Ask a relative or friend for availability to return home, as, once the operation is over, you may feel dizzy and confused and unable to drive a means of transport.

Any other precautionary measure, taken in addition to the three aforementioned, depends on the doctor and the patient in question.

Deepening: comparison between cardiac ablation and cardioversion

Cardiac ablation and cardioversion are two procedures with fairly similar aims.

In both cases, in fact, the aim is to restore the normal heart rhythm, altered by an arrhythmia.

So where do the differences lie?

Cardioversion, in its electric version, uses an instrument that emits electric shocks, called a defibrillator . These discharges, once transmitted, could cause episodes of thrombosis or embolism, as the heart of patients with arrhythmia often has blood clots inside it. Therefore, to avoid this possible complication, the patient begins, at least four weeks before the operation, a therapy based on anticoagulant drugs, which thin the blood and dissolve any blood clot present. Only after having taken this precaution, it is possible to undergo cardioversion.

How to do it

Cardiac ablation is an outpatient therapeutic treatment, therefore it is performed within a single day and, except for complications, does not involve any hospitalization.

The use of a truly singular catheter, capable of performing various functions, is introduced, which is introduced into the femoral or jugular vein and, from here, led to the heart. Once the latter is reached, the catheter is put into action, observing its effects step by step.

Below is a detailed description of each step of the procedure.

INITIAL PHASE: SEDATION AND CREATION OF AN ACCESS POINT

Shortly before the operation, the patient is sedated, in order to favor relaxation and because he might feel a slight discomfort in some particular moments of the procedure. However, he remains conscious .

The sedatives are injected using a needle-cannula, inserted in the forearm or in the hand. The pain, which is felt at the time of insertion of the needle-cannula, is minimal, sometimes almost imperceptible.

Once the sedation is completed, the operating doctor (or a specialist) anesthetizes the inguinal or neck area (where the femoral vein and the jugular vein are present, respectively), and applies another needle-cannula, in such a way as to facilitate catheter access.

CHARACTERISTICS OF THE CATHETER

The catheter used is not a normal catheter, but has various characteristics. He carries a contrast liquid and presents, at one end, electrodes and an energy source, called an ablator .

The contrast liquid acts as a tracer, because it allows the cardiologist to follow the catheter path on a monitor and know when it has reached the heart. The contrast liquid could cause damage to the kidneys (rare) and a slightly annoying sensation, at the time of its "loading" into the catheter (common).

The electrodes (usually three in number) are used to record the electrical activity of the heart, so as to identify which part of the organ does not function properly. In other words, through the electrodes, the whole cardiac muscle tissue (the myocardium) is analyzed piece by piece, looking for the aberrant area, which gives rise to the arrhythmia.

Figure: an example of a catheter for cardiac ablation. From the site: medgadget.com

The scaler, on the other hand, is, in fact, the instrument with which this aberrant tissue is destroyed, thus eliminating the cause of the heart problem. This device can be of different types: radiofrequency ( radiofrequency cardiac ablation ), laser ( cardiac ablation with laser ) or low temperature ( cardiac cryoablation ).

THE TRUE AND OWN PROCEDURE

The cardiologist introduces the catheter, through the needle-cannula (femoral or jugular, is the same for the purpose of the procedure), and directs it to the heart, using the contrast liquid and the connected monitor.

Once it reaches the heart, it activates the electrodes and starts probing all the heart tissue. The recording of electrical activity allows, as mentioned, to identify what is the area that causes the arrhythmia. Having traced the aberrant area, he operates the scaler, which destroys the pathological tissue. With the elimination of the small portion of myocardium that gave rise to the arrhythmia, the cardiac rhythm is regulated and the electrical impulses coming from the atrial sinus node are allowed to return to travel in a normal way.

During the entire procedure, anticoagulant drugs may be injected into the patient to prevent thrombus formation in the heart cavities.

Deepening: how to identify the area of myocardium, which causes the arrhythmia?

Some arrhythmias, such as atrial tachycardia or atrial fibrillation, alternate moments in which they cause symptoms at times when they are asymptomatic. It follows that tracing the heart area responsible for the arrhythmic disorder is not always a simple and immediate operation.

To solve this problem, an external pacemaker is used during cardiac ablation or, alternatively, some special drugs such as atropine, which tend to favor the appearance of the arrhythmia, latent in that specific moment of treatment. In other words, the cardiologist voluntarily induces the appearance of the alteration of the rhythm, in order to be able to better identify its origin.

DURATION OF THE PROCEDURE

Cardiac ablation generally lasts from 2 to 4 hours ; however, if complications arise, it can last even longer.

Figure: entrance sites for the catheter and the needle-cannula. In the figure, the possibility of inserting the catheter through the jugular vein is not indicated. From the site: india.columbiaasia.com

SENSATIONS DURING THE INTERVENTION

The patient may experience discomfort or pain :

When the two cannula needles are inserted, the one for the sedatives and the one for the catheter.
When the contrast liquid in the catheter is "charged".
When the energy source that destroys the aberrant heart tissue is put into operation.

These are very brief and usually mild sensations; however, in some cases, especially among the individuals most sensitive to pain, they can also be quite acute.

SPECIAL CASES

Some heart ablation procedures are performed with an open heart . On these occasions, for obvious reasons, general anesthesia is required, which makes the patient completely unconscious.

Post-operative phase

At the end of the operation, the patient is transferred to a recovery room and kept there for about 4-6 hours. During this time, heart rate and blood pressure are continuously monitored, in order to intervene promptly should post-operative complications appear.

In this time frame, it is likely to feel dizzy and confused : these are normal sensations, caused by sedative drugs and anesthetics.

RESIGNATION

If everything goes smoothly and if the treating cardiologist believes that the surgery has been successful, the patient can go home even on the day of cardiac ablation.

If, on the other hand, complications appear or the cardiac situation is unstable, the patient should spend the night in the hospital.

As recommended before the operation, for the return home it is necessary to get help from a relative or a friend.

HOW DOES IT FEEL?

After the cardiac ablation procedure, it is normal to feel confused and painful.

The state of confusion is due to sedative and anesthetic drugs, given during the surgery, and lasts a few hours.

The painful sensation, on the other hand, is caused by the invasiveness of the operation and generally continues for just under a week.

THE RETURN TO NORMAL ACTIVITIES

Except for complications, the return to everyday activities, such as work, takes place within a few days. The advice, usually, is to wait for the cessation of the sense of general pain, which characterizes the post-operative phase.

Risks of the transaction

Given the way in which the procedure is performed (from the insertion of the two cannula needles to the use of a catheter to destroy a small part of myocardium), cardiac ablation is considered a moderately invasive procedure . As such, it can involve risks and complications, sometimes even very serious ones. Here is what they consist of:

Blood loss and infections at the catheter insertion point.
Damage to venous vessels, which are crossed by the catheter.
Damage to heart valves caused by the catheter.
Further worsening of the arrhythmia. A pacemaker is needed to normalize the conduction of electrical signals and solve this problem.
Thromboembolism, or formation of blood clots (thrombi or emboli) in the legs or lungs. Usually, to prevent these complications, anticoagulants are injected into the patient during cardiac ablation.
Stroke or heart attack .
Narrowing of the veins that lead to the lungs and heart ( stenosis of the pulmonary veins ).
Kidney damage caused by the contrast liquid. However, this is a very rare circumstance.
Death. It is a very rare situation, which however can occur.

The possibility of running into one of these complications increases dramatically if you suffer from diabetes or some kidney disease . This is one of the reasons why, before subjecting an individual to cardiac ablation, it is necessary to subject him to all the clinical controls of the case.

Results

Generally, cardiac ablation is fairly successful, however, in some circumstances, the procedure must be repeated or a maintenance drug therapy adopted. Maintenance therapy is a treatment that is used to maintain the results obtained with a previous therapeutic treatment: in this specific case, the aim is to keep the heart rate within normal limits.

HOW TO OBTAIN THE BEST RESULTS?

If you adopt a healthier lifestyle, for example by reducing the amount of salt to season foods or by doing more physical activity (for all advice, see the table below), heart health is improved, consequently also the impact that a therapy, like cardiac ablation, has on it.

Table: tips to follow, to improve general and heart health.