Fainting/ Blackouts

Fainting—or “syncope”—is a temporary loss of consciousness caused by a sudden drop in blood flow to the brain. Most episodes last only a few seconds, and many people recover quickly, but recurrent or unexplained blackouts should always be assessed, as they can sometimes signal an underlying heart condition.

What Is Cardiac Syncope?

Cardiac syncope occurs when a problem with the heart disrupts normal circulation. This may be due to an abnormal heart rhythm, a structural abnormality, or a condition that affects the heart’s ability to pump blood effectively. Unlike a simple faint, cardiac syncope often happens without a clear trigger and may occur during exertion, while lying down, or suddenly without warning.

Fainting That Is Not Cardiac

Many people faint due to benign causes such as dehydration, standing for long periods, pain, or emotional distress—known as vasovagal syncope. Others may feel light-headed or experience “near-syncope” without fully losing consciousness. Although these causes are generally less serious, recurrent episodes still warrant evaluation to rule out cardiac involvement.

Symptoms to Look Out For

Some people notice warning signs such as dizziness, nausea, a racing or irregular heartbeat, blurred vision, or feeling unusually hot or sweaty. If these symptoms occur, sitting or lying down with your legs raised can help restore blood flow to the brain and may prevent a full faint.

Cardiac Conditions That Can Cause Syncope

Heart-related causes of blackouts include:

Fast or slow heart rhythms (e.g., ventricular tachycardia, heart block)
Electrical disorders such as Brugada syndrome or inherited arrhythmia syndromes
Narrowing of the aortic valve (aortic stenosis)
Structural heart disease or cardiomyopathy
Long or short QT interval conditions
Rarely, serious conditions such as aortic dissection

Because cardiac syncope can be associated with increased risk, timely specialist assessment is essential.

How Syncope Is Diagnosed

Your assessment begins with a detailed consultation, including a review of symptoms, medical history, family history and a focused cardiovascular examination. Depending on your presentation, I may recommend one or more of the following tests to identify a cardiac cause:

ECG to assess electrical activity
Echocardiogram to examine heart structure and function
Exercise stress testing to identify exertional triggers
Holter or ambulatory ECG monitoring for intermittent rhythm problems
Implantable loop recorder for infrequent but concerning episodes
Tilt table testing if autonomic causes are suspected
Blood tests, cardiac MRI, or CT where appropriate
Electrophysiology (EP) study in selected cases to pinpoint complex rhythm abnormalities

This comprehensive approach ensures we identify the underlying cause and assess your individual risk.

Treatment Options

Your treatment plan is tailored to the cause of your symptoms. Options may include:

Adjusting or starting medications to stabilise blood pressure or heart rhythm
Catheter ablation for arrhythmias causing syncope
Pacemaker implantation for slow-heartbeat–related episodes
Implantable cardioverter defibrillator (ICD) for high-risk ventricular arrhythmias
Referral for structural heart interventions if needed (e.g., aortic valve replacement, coronary procedures)

We will discuss any recommended treatment in detail to ensure you understand the benefits, risks, and expected outcomes.

Providing reassurance to a patient who had fainted

Preventing Future Episodes

Managing the underlying cause is the most effective long-term prevention. For common fainting episodes, specific physical counter-pressure techniques—such as leg-crossing, hand-gripping, or tensing the calves and thighs—can help abort an episode. Maintaining good hydration and avoiding known triggers may also reduce symptoms, particularly in vasovagal syncope.