cardioversion

Generality

Cardioversion is the therapeutic procedure implemented to restore sinus rhythm in a person suffering from arrhythmia.

There is electrical cardioversion and pharmacological cardioversion. The first uses an instrument, the defibrillator, which emits electrical discharges; the second, instead, consists in the administration of certain medicines, the anti-arrhythmics.

The results of cardioversion are usually more than satisfactory; however, to achieve lasting effects, it is good to follow the maintenance therapy, prescribed by the doctor, and adopt a healthy lifestyle.

What is cardioversion?

Cardioversion is a therapeutic procedure that serves to restore the normal rhythm of the heart ( sinus rhythm ), in all those people who suffer from a cardiac arrhythmia .

There are two types of cardioversion, electric and pharmacological.

Electrical cardioversion uses electric shocks (or shocks), generated by an instrument (the defibrillator) and transmitted to the patient by means of electrodes applied to the chest.

Pharmacological cardioversion, on the other hand, involves the administration of specific antiarrhythmic drugs.

Cardioversion is usually a planned treatment, which takes place in a hospital, but without hospitalization. In fact, at the end of the therapy, if everything has gone well, the patient can already return home.

DIFFERENCE BETWEEN CARDIOVERSION AND DEFIBRILLATION

Defibrillation and electrical cardioversion, although based on the same operating principle, present substantial differences, so it is not really correct to consider them the same thing.

Defibrillation is a medical procedure put into practice especially in emergencies, where the patient's life is in serious danger. Such situations are, for example, ventricular fibrillation or wristless ventricular tachycardia, which arise and evolve very quickly to cause a heart arrest ( cardiac arrest ).

Defibrillation, therefore, is not a planned intervention, as is cardioversion.

There is also a difference from the point of view of electric discharges: shocks, in fact, are much stronger than those of electrical cardioversion, since the energy transmitted is used to restart the heart, not to adjust its rhythm.

When you run

Cardioversion can be implemented in all those situations in which the heart beats faster (tachycardia) or irregularly (fibrillation and flutter), compared to the normal sinus rhythm.

The forms of arrhythmia, for which cardioversion is ideal, are supraventricular achicardias (paroxysmal and non-paroxysmal), atrial fibrillation, atrial flutter and ventricular tachycardia with wrist ; these, in contrast to ventricular fibrillation and pulse-free ventricular tachycardia (the most indicated treatment being defibrillation), are less serious and more easily resolved circumstances.

Figure : Atrial fibrillation is an arrhythmia that requires cardioversion.

Not surprisingly, often the procedure is scheduled in advance and, before putting it into practice, the cardiologist has time to perform a series of clinical tests on the patient.

CHOICE OF THE TYPE OF CARDIOVERSION

The choice of type of cardioversion (pharmacological or electrical) depends on the patient's condition and the cardiologist's assessments.

If, once these considerations are concluded, the practice of one or the other is indifferent, the patient can opt for the one that he feels least annoying: usually, in these cases, there is a preference for pharmacological cardioversion, since they are feared electrical discharges.

Risks of the intervention

If the cardiologist takes all the necessary precautions, the risk of cardioversion producing complications is very rare.

Possible problems are:

• Detachment of a blood clot . It is quite frequent that those suffering from arrhythmia (especially fibrillation and atrial flutter) also present one or more blood clots inside the heart. This or these clots, after cardioversion, could detach from their seat and, being transported by the blood circulation, reach various districts of the body, with sometimes dramatic results (embolism). A classic example of this eventuality is represented by the stroke, caused by a blood clot that has reached the brain. To prevent this, the patient is given several anticoagulant medications for a few weeks, so as to "dilute the blood" and "dissolve" the clots present.
• Abnormal heart rhythm . It may happen that, after cardioversion, the heart rhythm, instead of returning to normal, develops another anomaly. If this happens, the treatment must be repeated, adapting it to the characteristics of the new disorders that have arisen.
• Low blood pressure . It is possible that, after cardioversion, the patient may experience episodes of low blood pressure, which however improve within a few days and without any treatment.
• Burns on the skin . It is a drawback of electrical cardioversion; the burns are due to the electrodes, which, applied to the chest, transmit the electric discharge.

Preparation

Before cardioversion surgery, there are some diagnostic tests, to which to undergo, and certain precautions to be taken.

Diagnostic tests . The most important is, without doubt, the so-called transesophageal echocardiogram, which is carried out to "find" any blood clots inside the heart. The examination procedure involves the use of an ultrasound probe, which, applied to one end of a flexible tube (a catheter), is inserted into the mouth and lowered to the esophagus. Once positioned at the appropriate point, the probe projects clear images of the heart and its internal anatomy onto a monitor.

In addition to the transesophageal echocardiogram, all those routine pre-operative diagnostic tests (blood pressure analysis, blood tests, etc.) are performed.

Pre-intervention precaution . Before the procedure, you must refrain from eating and drinking for at least 6/12 hours, as general anesthesia is provided. If the patient is taking any medications, he should tell his doctor and ask for advice on what to do.

Frequently asked questions about transesophageal echocardiography

How long does it last?

The duration is about 20-25 minutes.

Is it painful?

The patient may experience pain when passing the catheter through the mouth and the esophagus. It is a tolerable sensation, which can be prevented by light sedation.

Do you have to fast before the exam?

Yes, you need to be fasting for at least 6/12 hours.

Do you need hospitalization?

No, however it is advisable to be accompanied by some family member (or friend) because the anesthetic, used for sedation, can alter the patient's driving skills.

WHAT TO DO IF THERE ARE BLOOD COAGULES IN THE HEART?

If, from the transesophageal echocardiogram, the presence of one or more clots emerges, the cardiologist prescribes to the patient some anticoagulant drugs, to dilute the blood. The treatment, for it to take effect, must last for at least four weeks. Only once this anticoagulant treatment is considered complete can cardioversion be performed.

The most used anticoagulant is the Coumadin .

Procedure - Electrical cardioversion

Electrical cardioversion requires general anesthesia to quell the patient.

Electric shocks are emitted by an instrument, called a defibrillator, which is connected to the patient by means of electrodes, applied to the chest (or even on the back).

Figure : instrumentation for electrical cardioversion. The electrodes are the two plates visible in the photo.

The defibrillator is an "intelligent" device, because it is able to record the cardiac rhythm of the patient and alert the cardiologist when it is the most suitable moment to release the discharge.

The intensity of the shocks is at the discretion of the doctor and depends on the disorder afflicting the patient.

SEDATION

General anesthesia involves the use of anesthetics and painkillers, which render the patient unconscious and insensitive to pain.

The administration of these drugs, carried out intravenously, occurs before and throughout the procedure.

Once the cardioversion has been completed, in fact, the pharmacological treatment ceases to allow the patient to regain consciousness.

Some anesthetics (for example, lidocaine ) have a dual function, analgesic and anti-arrhythmic. Therefore, they are administered with a dual purpose: to anesthetize the patient and promote the recovery of normal cardiac activity.

PATIENT MONITORING

To see how a patient's heart responds to electric shocks, a continuous electrocardiogram is used. Only in this way, in fact, the cardiologist is able to know how the situation evolves after each shock and, possibly, if he has to make changes to the current intensity emitted by the defibrillator.

Figure: an electrocardiographic trace. It can be seen that the electric discharge (shock) restores the normal heart rhythm, previously altered by atrial fibrillation.

DURATION

Once the patient is sedated, electrical cardioversion takes place within minutes. The duration varies from patient to patient and depends on how long and how many discharges it takes to restore sinus rhythm.

AFTER THE INTERVENTION

Electrical cardioversion is an outpatient procedure, which takes place in less than a day and does not require hospitalization.

Before discharging the patient, however, it is good to keep him under observation for at least an hour; this is a normal precautionary measure, in the event that complications arise.

The fundamental points of the post-intervention phase are:

• Assistance of a family member . It is important to remember that general anesthesia could reduce the ability to sense and, in general, attention. For this reason, it is a good idea to be taken back home by a family member or friend, as it is strongly advised not to start driving a vehicle immediately.
• Anticoagulant drugs . Even if the heart, before surgery, did not present blood clots inside it, however, anticoagulants are prescribed for preventive purposes.

• Maintenance therapy . Always for preventive purposes and to consolidate the effects of electrical cardioversion, the patient is prescribed a treatment based on antiarrhythmic drugs. If it is well tolerated by the patient, this therapy can last even a lifetime. Any decision regarding the dosage or interruption of the treatment is solely and exclusively up to the doctor.

Procedure - Pharmacological Cardioversion

Pharmacological cardioversion involves the administration of antiarrhythmic drugs, either intravenously or orally.

The antiarrhythmics available are divided into 4 classes, based on the mechanism of action:

• Sodium channel blockers (class I) : exerting a blocking action on the so-called sodium channels, stabilizing the heart rhythm. There are three different subclasses: IA, IB and IC (see the table below).

• Cardioselective beta-blockers (Class II) : slow down the heart rate, specifically blocking beta-1 adrenergic receptors acting on the heart. The term cardioselective distinguishes them from beta-2 receptor beta-blockers, which have effects on the bronchi and blood vessels.

• Potassium channel blockers (Class III) : restore normal heart rhythm by blocking potassium channels. In cases of atrial fibrillation and flutter, the azimilide and ibutilide are widely used; in cases of paroxysmal supraventricular arrhythmias, sotalol is usually administered; in many tachycardias, amiodarone is used.

• Calcium channel blockers (Class IV) : slow heart rate and regulate it, blocking calcium channels. The most commonly administered are diltiazem and verapamil.

AFTER THE ADMINISTRATION OF THE ANTI-ARITHMIC

After drug administration, the patient is subjected to an electrocardiogram (as in electrical cardioversion), to see what is the response to the treatment.

If everything proceeds without complications, the doctor plans the most adequate maintenance therapy .

The latter is based on antiarrhythmics and serves to maintain the heart rate within the desired values.

DURATION

Pharmacological cardioversion, by itself, is very short. In fact, once the drug is taken, it can be considered completed.

MAINTENANCE THERAPY

Maintenance therapy, if well tolerated by the patient, can last even a lifetime.

On the contrary, if there should be any problems related to the continuous intake of antiarrhythmics, the treatment should be interrupted, observing the subsequent reactions of the patient.

In these situations, every decision is up to the cardiologist, who also decides how and whether to replace maintenance therapy.

Results

In most cases, cardioversion (both electrical and pharmacological) restores normal heart rhythm.

When it does not have the desired success (usually, the disorders reappear at a distance of a few hours or days), the only solution is to repeat the procedure, perhaps adjusting the power of the electric discharge or the pharmacological dose.

HOW TO PREVENT RELATIONS?

A healthy lifestyle and some health precautions help prevent arrhythmias, especially in people who are predisposed to these heart conditions or who have already suffered from them in the past.

Here are some important medical tips:

• Eat healthy foods and maintain a normal body weight
• Reduce the salt taken with the diet, so as not to raise the blood pressure
• Do physical activity (commensurate with your possibilities)
• Limit or avoid caffeine intake
• Not smoking
• Limit or avoid alcohol altogether
• Keep cholesterol levels low
• Reduce stress situations
• Pay attention to any medicine you take because it could alter your stabilized heart rhythm due to cardioversion.