Cardioversion preparation blood tests

Overview

Cardioversion is a medical procedure that uses a controlled electric shock to restore a normal heart rhythm in people with certain irregular heartbeats (arrhythmias). Before the procedure, you will need blood tests to check your overall health, ensure the blood thinner levels are safe, and rule out other conditions that might affect the procedure. These tests help your doctor plan a safer cardioversion.

Cardioversion is a common procedure for people with atrial fibrillation or atrial flutter, especially when medications don't control the rhythm.

It mainly affects adults with heart rhythm disorders, often over 60, but can be performed at any age if needed.

Symptoms

Common symptoms

• Heart palpitations (feeling like your heart is racing, fluttering, or pounding)
• Shortness of breath
• Dizziness or lightheadedness
• Chest discomfort
• Fatigue or weakness

Symptoms in children

• Palpitations or skipped heartbeats
• Poor feeding or pale skin in infants
• Fainting or near-fainting with exercise

Symptoms in older adults

• Sudden confusion or tiredness
• Feeling faint or dizzy when standing up
• Shortness of breath with light activity

Causes

Main causes

• Heart rhythm disorders like atrial fibrillation or atrial flutter – these cause the upper chambers of the heart to beat fast and irregularly.
• Other heart conditions such as valve disease, heart failure, or coronary artery disease

Risk factors

• High blood pressure
• Older age (over 60)
• Obesity
• Diabetes
• Heavy alcohol use or stimulant drugs
• Sleep apnoea
• Family history of heart rhythm problems

When to see a doctor

See a doctor urgently if:

• Heart palpitations that last more than a few minutes or come with chest pain, shortness of breath, or fainting

Book a routine appointment if:

• If you have been told you have an irregular heartbeat and are scheduled for cardioversion, follow your doctor's advice for pre‑procedure blood tests.

Diagnosis

Your doctor diagnoses an arrhythmia using an ECG (electrocardiogram) which records your heart's electrical activity. Blood tests help confirm the arrhythmia type and check for underlying causes like electrolyte imbalances or thyroid problems.

Tests that may be done

• Electrocardiogram (ECG)
• Echocardiogram (ultrasound of the heart)
• Blood tests: complete blood count, kidney function, electrolytes (sodium, potassium, magnesium), thyroid function, and clotting time (INR if on warfarin)
• Holter monitor (portable ECG worn for 24 hours or longer)

What to expect at your appointment

You will have blood drawn from a vein in your arm, usually a few days before the procedure. It takes about 10 minutes. Your doctor will review the results to see if any adjustments are needed before the cardioversion.

Treatment

Cardioversion is done under light sedation or anaesthesia. Pads or paddles on your chest deliver a brief electric shock. The goal is to reset the heart's rhythm to normal. Blood tests beforehand help make sure the procedure is safe.

Self-care at home

• Follow any instructions given by your doctor about eating or drinking (usually nothing by mouth for several hours).
• Continue your regular medicines unless told otherwise.
• Arrange for someone to drive you home after the procedure.

Medical treatments

Doctors may also use medicines to control heart rate or rhythm (called antiarrhythmics) before or after cardioversion. The specific medicine and dose depend on your condition and blood test results. Your healthcare provider will decide what's best for you.

When is surgery considered?

If cardioversion does not work or arrhythmias keep coming back, a procedure called catheter ablation may be considered. This involves threading a thin tube to the heart to destroy the tiny area causing the abnormal rhythm.

Living with this condition

After successful cardioversion, most people return to normal activities within a day or two. You may need to avoid heavy lifting or driving for a short time.

Lifestyle tips

• Track your pulse regularly and note any changes.
• Avoid triggers like too much caffeine or alcohol.
• Manage stress with relaxation techniques or gentle exercise.

Diet and exercise

Eat a heart‑healthy diet with plenty of fruits, vegetables, whole grains, and lean protein. Limit salt and saturated fats. Moderate exercise, like walking, is usually safe after the procedure – ask your doctor when to start.

Mental health and emotional wellbeing

Having a heart rhythm problem can be worrying. It is normal to feel anxious or stressed, especially before a procedure. Talk to your healthcare team about any concerns – they can offer support and resources.

Prevention

Not all arrhythmias can be prevented. But managing risk factors like high blood pressure, diabetes, and obesity can lower your chance of developing them. Staying active and avoiding heavy alcohol use also help.

Vaccines

While vaccines do not prevent arrhythmias, staying up‑to‑date with flu and pneumonia shots is important for people with heart conditions.

Screening programmes

If you have a family history of heart rhythm problems or certain conditions (like sleep apnoea), your doctor may recommend periodic ECGs.

Complications

If left untreated

• Stroke (when blood clots form in the heart and travel to the brain)
• Heart failure (the heart cannot pump effectively)
• Worsening arrhythmia that leads to more symptoms

Long-term outlook

With proper care – including pre‑procedure blood tests and follow‑up – cardioversion is safe and effective for many people. Most regain a normal rhythm quickly. Medications and lifestyle changes can help maintain a healthy heart over time.

Find support

External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.