Cardioversion (Latin: cardio = heart, vertere = to turn) refers to a procedure used to restore the heart’s sinus rhythm. It is used to treat cardiac arrhythmias such as atrial fibrillation and is intended to restore a regular heartbeat. The goal of the treatment is to restore the sinus rhythm—that is, a stable and regular heart rhythm—which is necessary for the heart to pump efficiently.
Below you will find further information as well as a selection of specialists in cardioversion.
Cardioversion is a treatment for cardiac arrhythmias in which an irregular heartbeat is restored to a regular rhythm. “Cardi-” stands for heart and “-version” means to restore. Cardioversion can be performed using special medications or electrical stimulation.
Drug-based cardioversion uses so-called antiarrhythmic drugs, which include, for example, flecainide, amiodarone, and propafenone. “Anti” here means “against,” and “arrhythmia” refers to an irregular heartbeat.
When electrical current is used, the procedure is also referred to as electrical cardioversion, which can be performed externally or internally using special pacemakers. In most cases, external electrical cardioversion is performed using electrodes placed on the patient’s chest. A synchronized electrical shock is delivered, which is intended to restore the heart’s rhythm and enable a return to sinus rhythm.
The pacemaker for a healthy, regular heartbeat is the so-called sinus node, which is why a normal heartbeat is also called sinus rhythm. The sinus node is a comma-shaped structure approximately 3 mm wide and 10 mm long, located in the right atrium of the heart. It acts as a pacemaker, sending electrical signals to the four chambers of the heart (two atria and two ventricles) and thereby controlling the contractions of the heart muscle. A sinus rhythm corresponds to a steady pulse and thus represents the normal state. However, depending on physical activity, the number of heartbeats per minute varies between 40 beats (during deep sleep) and over 180 beats during maximum physical exertion. This, too, is controlled by the sinus node.
When the rhythm becomes irregular, irregular heartbeats occur. In these cases of arrhythmia, the heartbeat itself continues, but without the necessary control of electrical impulses by the sinus node. This can be because other areas of the heart take over the electrical impulses that stimulate the heart, effectively “overriding” the sinus node. Often, however, it is also because the sinus node itself becomes diseased.
Among the most common forms of arrhythmia are atrial fibrillation and atrial flutter. In these conditions, the electrical impulses that control the heart rate originate from various locations within the atria. Both conditions are classified as supraventricular tachycardias, in which the electrical impulses arise above the ventricles.
The causes of atrial fibrillation are varied; often it is a combination of
A heart attack is also one of the most significant risk factors for the development of cardiac arrhythmias.
Cardioversion is necessary in an emergency when sudden cardiac arrhythmias lead to loss of consciousness and fainting. This is the case, for example, with ventricular fibrillation, which can occur during a heart attack, among other situations. Functionally, ventricular fibrillation causes cardiac arrest because blood can no longer be effectively pumped out of the heart. Strictly speaking, however, this is not cardiac arrest; rather, it is caused by continuously active heart muscle that makes a regular heartbeat impossible. In these emergency situations, external cardioversion is performed using a defibrillator (“shock device”). During the procedure, a brief electrical shock is delivered, which temporarily interrupts the heart’s electrical activity and thereby allows a regular rhythm to be reestablished.
There are also elective—that is, planned—indications for cardioversion. The most common cause is chronic atrial fibrillation, which persists over a long period of time. This leads to a persistent lack of coordination in the heart muscle’s activity, reducing the effectiveness with which blood is pumped into the blood vessels. Many people affected experience this as a racing heart and can physically feel the irregularity of their heartbeats. Signs of weakness and dizziness, as well as nausea and restlessness, are also possible. If these signs are present, cardioversion should be considered, especially in younger and active patients.
Atrial fibrillation alone is generally not dangerous; however, there is a significantly increased risk of blood clots (medically known as thrombi) forming in the irregularly beating atria. Thrombi form most frequently in the areas where the atria bulge outward.
This is caused by the slowed flow of blood. These clots can eventually be carried along by the bloodstream and dislodged into a major artery. This is called an embolism. Examples include a sudden blockage in a leg artery, which manifests as a pronounced sensation of cold, or a stroke, if the clot is carried upward into the brain.
To prevent an acute stroke, anticoagulation (from the Latin coagulare, meaning “to coagulate”)—a therapy that inhibits blood clotting—is administered. This treatment is continued for three to four weeks, and often for years, depending on the patient’s individual indication and personal risk profile.
The diagnosis and non-surgical treatment of heart diseases are the responsibility of specialists in internal medicine and cardiology. These specialists (cardiologists) safely perform drug therapies and catheter-based treatments. Non-surgical therapy thus includes all invasive (catheter-based) and pharmacological measures except for heart surgery, which is performed by cardiac surgeons.
Not every patient with atrial fibrillation needs cardioversion. Many patients have had atrial fibrillation for years without experiencing serious problems. However, since atrial fibrillation is associated with an increased risk of stroke, the vast majority of patients are treated with an anticoagulant. Cardioversion—that is, restoring a regular sinus rhythm—is indicated for patients with recently onset atrial fibrillation, a very rapid heart rate (tachycardia), or chest pain (myocardial ischemia) caused by impaired blood flow to the heart muscle.
If atrial fibrillation or flutter does not resolve on its own within 48 hours, cardioversion is recommended. This can be performed either pharmacologically or electrically.
There are two treatment options: electrical or pharmacological. With pharmacological therapy, an antiarrhythmic drug is used to restore sinus rhythm. The goal of this treatment is to achieve a regular heart rhythm.
If the desired state cannot be achieved through pharmacological cardioversion, electrical cardioversion is performed. In this procedure, a direct current pulse is delivered via a defibrillator at the level of the chest wall. The electrical shock is delivered in sync with the heart’s activity to ensure that sensitive phases of the cardiac cycle are not disrupted.
The treatment is painless, lasts only a few minutes, and is performed under brief general anesthesia. During electrical cardioversion, the patient is monitored by an ECG (electrocardiogram, which records heart activity). After the treatment, a follow-up appointment is required to verify that the sinus rhythm has been maintained.
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Patients who already have a pacemaker may not undergo cardioversion. However, there is the option of a special pacemaker lead adjustment that allows for a lower-risk treatment.
A high risk is posed by blood clots in the atrium, which frequently form in the context of atrial fibrillation. It is possible for these clots to break loose during electrical cardioversion and lead to an embolism. For this reason, a transesophageal echocardiogram (heart ultrasound) is usually performed immediately before cardioversion. In this procedure, known as a “swallow echo,” a probe is inserted through the esophagus and advanced to the stomach. Since the esophagus is located immediately behind the heart, transesophageal echocardiography can provide precise images from this vantage point, revealing any thrombi in the atrium. If thrombi are detected, cardioversion must be performed under specific anticoagulation therapy.
A fundamental risk lies in the accidental triggering of additional cardiac arrhythmias by the defibrillation itself. This would worsen the condition rather than improve it.
In general, cardioversion is considered helpful and promising for atrial fibrillation, especially when it cannot be controlled with medication and causes symptoms.
The long-term success of cardioversion can only be assessed on a case-by-case basis and is at least more likely with the additional use of rhythm-maintaining medications. Studies show that the long-term success rate of cardioversion is higher for atrial fibrillation that has been present for a shorter period of time than for rhythm disorders that have persisted for many years.
Nevertheless, atrial fibrillation often recurs even after cardioversion. It is possible to repeat the procedure, but even a repeat treatment does not guarantee success.
The longer the arrhythmia has been present, the more difficult it is to maintain a sinus rhythm permanently.
If no lasting success is achieved despite multiple cardioversions and medication, catheter ablation may be an option. In this procedure, specific areas of the heart muscle tissue are ablated to permanently prevent further electrical disturbances. Here, too, the chances of success vary and must be assessed on a case-by-case basis.
1. What is cardioversion?
Cardioversion is a procedure used to treat cardiac arrhythmias in order to restore a normal heart rhythm.
2. When is cardioversion performed?
It is often indicated for persistent atrial fibrillation, especially if symptoms are present or if the heart rhythm has been irregular for more than 48 hours. In many cases, the procedure can be performed on an outpatient basis.
3. How is electrical cardioversion performed?
During external electrical cardioversion, a defibrillator delivers a controlled electrical shock designed to resynchronize the heart’s rhythm.
4. Is further treatment necessary after cardioversion?
After successful treatment, anticoagulation (blood-thinning therapy) is often continued to reduce the risk of strokes caused by potential blood clots.
Every physician listed in the Leading Medicine Guide has attained the highest level of training and certification within their respective medical specialty society. Furthermore, we contacted this physician based, among other factors, on their case volume (surgeries, treatments, and therapies), which we determined by cross-referencing various publicly available sources. Following discussions with the selected physicians and the directors of the medical facilities, as well as a subsequent internal review, they were admitted to the Leading Medicine Guide.
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