Cardioversion (Electrical) · EP Patient Education Library

What a cardioversion is

A cardioversion is a planned, controlled electrical reset of the heart. We deliver a brief shock — timed precisely to a specific point in the heart’s electrical cycle — that depolarizes the entire heart muscle at once. When the muscle repolarizes, the sinus node usually re-establishes itself as the leader, and normal rhythm resumes. It works for the same reason a power-cycle works on a frozen computer: it interrupts whatever disorganized activity was running and lets the system restart cleanly.

It is important to understand what cardioversion is not. It is not a defibrillation in the cardiac arrest sense — that shock is unsynchronized and used only when the heart is in a life-threatening rhythm and the patient is not awake. A planned cardioversion is synchronized, you are sedated and comfortable, and it is one of the shorter procedures we do in cardiology.

Why we do it

The most common reason is atrial fibrillation or atrial flutter that we want to convert back to normal rhythm — either because the patient is symptomatic, because rate control alone hasn’t been enough, or because we want to see how the patient feels in sinus rhythm before deciding on longer-term strategy. We also use it occasionally for hemodynamically tolerated ventricular tachycardia, and as part of certain ablation protocols.

The decision to cardiovert is usually shared. Some patients feel terrible in AFib and want their rhythm back as quickly as possible. Others have lived with AFib for years and barely notice it. Knowing how you feel in normal rhythm is genuinely useful — and a cardioversion is sometimes the cleanest way to find out.

The stroke-prevention question

This is the most important planning step. When the upper chambers fibrillate, blood can stagnate in the left atrial appendage, and a clot can form there silently. The moment we restore coordinated atrial contraction, that clot — if one exists — can be ejected into the bloodstream and travel to the brain.

We handle this in one of two ways:

Three weeks of confirmed, uninterrupted anticoagulation before the procedure, and at least four weeks of anticoagulation afterward. This is the standard approach when the timeline allows.
A transesophageal echocardiogram (TEE) — a probe passed down the esophagus, the same day as the cardioversion, to look directly at the left atrial appendage and confirm there’s no clot. We use this when we need to cardiovert sooner, or when anticoagulation history is uncertain.

Either path is acceptable; we choose based on your individual situation. After the cardioversion, anticoagulation continues — for at least a month, and usually longer based on your overall stroke risk.

The procedure step by step

You’ll arrive having fasted overnight. Pads are placed on the chest and back. We hook up the monitors and an IV. An anesthesiologist or anesthesia provider gives a short-acting sedative — propofol or similar — and you fall asleep within a few seconds. The shock itself is delivered within the next half-minute, synchronized to your heart’s own R wave so it lands at a safe point in the cycle. If the first attempt doesn’t convert, we may repeat at a higher energy. Most patients require only one or two shocks total. You wake up in the same bay within minutes.

Recovery

You’ll be monitored for about an hour to confirm the rhythm is stable. Most patients go home within a couple of hours. Because of the sedation, you cannot drive that day and you’ll need someone to take you home. There may be mild skin redness where the pads were, sometimes a brief sore-chest feeling, but very few people report significant discomfort.

When we’d choose another option

For patients who are doing well on rate control and don’t have bothersome symptoms, cardioversion is not necessary. For patients who keep relapsing into AFib within days or weeks of repeated cardioversions, we usually pivot — either to an antiarrhythmic medication, to catheter ablation, or to accepting the rhythm as permanent and focusing on rate control and stroke prevention. A single cardioversion is a useful tool, but repeated cardioversions without a longer-term plan rarely make sense.

Watch

Short videos to help illustrate this topic. Embedded from the original channels — content belongs to them.

Video pending Add a youtube video ID to display: What to expect during an electrical cardioversion

What to expect during an electrical cardioversion · Academic cardiology channel (Cleveland Clinic / Mayo) · Add a short patient-facing explainer.

Video pending Add a youtube video ID to display: Why we sometimes need a TEE first

Why we sometimes need a TEE first · Manufacturer or academic animation · Add a clip showing TEE imaging of the left atrial appendage.

Informed Consent — At a Glance

A plain-English summary of what we discuss before this procedure. This is not a substitute for the formal consent conversation with Dr. Colombowala.

Benefits

✓Restores normal rhythm in roughly 90% of cardioversions for AFib or atrial flutter.
✓Often produces immediate, dramatic relief of symptoms — fatigue, breathlessness, palpitations.
✓Helps us understand how much of a patient's symptoms come from the abnormal rhythm itself, which guides future decisions.
✓Can break a cycle of tachycardia-mediated heart-muscle weakening when rate control alone has not been enough.

Risks

⚠Stroke or TIA from a clot dislodging at the moment of cardioversion — risk is very low when anticoagulation is in place or when TEE has cleared the appendage.
⚠Brief slow heart rate or pause after the shock (usually self-resolving; rarely requires pacing).
⚠Skin irritation or minor burns at the pad sites.
⚠Risks of sedation: low blood pressure, breathing depression, allergic reaction (very rare).
⚠Recurrence of the arrhythmia — sometimes within minutes, sometimes days or weeks later.
⚠Damage to a pacemaker or ICD pulse generator (uncommon; we position pads to minimize this and check the device afterward).

Alternatives

↔Pharmacologic cardioversion — using an antiarrhythmic drug to restore rhythm instead of a shock.
↔Rate control alone — accepting the abnormal rhythm and slowing the heart rate with medication.
↔Catheter ablation as a more definitive rhythm-control strategy.
↔Watchful waiting in patients who are minimally symptomatic and well rate-controlled.

During the procedure

You'll be in a monitored bay with pads placed on the chest and back. An anesthesia colleague will give a short-acting sedative — you'll fall asleep within seconds. Once you're under, we deliver a single synchronized shock timed to the heart's own electrical cycle. The shock itself takes a fraction of a second. If the first shock doesn't convert the rhythm, we may try one or two more at higher energy.

Recovery

You'll wake up in the same bay within a few minutes, usually with no memory of the shock. We monitor you for about an hour to confirm the new rhythm is stable. Most patients go home the same day, often within a couple of hours. You cannot drive that day because of the sedation. Anticoagulation continues for at least four weeks after the cardioversion — sometimes indefinitely depending on your individual stroke risk.