Sick Sinus Syndrome in Singapore: Symptoms, Causes and Treatment

Sick sinus syndrome is a group of rhythm problems caused by the heart’s natural pacemaker – the sinus node – no longer working reliably. As a result the heart may beat too slowly, pause for long stretches, or swing between slow and fast rhythms. It is a type of arrhythmia (an abnormal heart rhythm) that becomes more common with age. If you have just been told you have sick sinus syndrome or sinus node dysfunction, this page explains what it is, its symptoms, why it develops, and how it is diagnosed and treated, often with a pacemaker. It is general information and not a substitute for advice from your own doctor.

What Is Sick Sinus Syndrome?

The sinus node is a small cluster of specialised cells in the right atrium that sets the pace of every heartbeat. In sick sinus syndrome (also called sinus node dysfunction), this natural pacemaker becomes unreliable. It may fire too slowly, take long pauses, or fail to speed up when you exercise.

A characteristic pattern is the tachy-brady syndrome, in which the heart alternates between a slow rhythm (bradycardia) and bursts of a fast rhythm such as atrial fibrillation (a fast, irregular rhythm from the upper chambers). This combination is common and can make treatment more complex, because slowing the fast episodes can worsen the slow ones. Sick sinus syndrome mostly affects older adults, as the sinus node tissue is gradually replaced by scar over the years. It is one specific cause of a slow heart rate; the wider group of slow-rhythm problems, including conduction faults lower down in the heart, is covered under bradycardia and heart block.

Sick Sinus Syndrome Symptoms

Symptoms come from the heart running too slowly or pausing, so the brain and body receive too little blood:

• Fatigue and low energy
• Dizziness or light-headedness
• Fainting or near-fainting (syncope)
• Breathlessness, especially on exertion
• Palpitations – a fluttering or racing feeling during the fast episodes
• Reduced exercise tolerance, because the heart rate does not rise as it should
• Confusion or memory difficulty in older people

Symptoms are often intermittent and vague, and can easily be mistaken for normal ageing, which is why the condition is sometimes diagnosed late.

When to Seek Emergency Help

Call 995 if someone:

• Faints and does not recover quickly, or collapses
• Has a very slow pulse together with chest pain, severe breathlessness or confusion

A blackout with no warning, or fainting that causes injury, needs urgent assessment.

Causes and Risk Factors

• Ageing and fibrosis – the most common cause, as sinus node cells are gradually replaced by scar tissue over decades.
• Coronary artery disease and previous heart attack – reduced blood supply can damage the sinus node.
• High blood pressure and other long-standing heart strain, both common in Singapore.
• Previous heart surgery involving the atria.
• Medications – drug classes such as beta-blockers, calcium channel blockers and some anti-arrhythmic drugs can slow the sinus node, sometimes unmasking an underlying problem.
• Other factors – an underactive thyroid, electrolyte disturbances, and, less commonly, inherited conditions in younger patients.

How Sick Sinus Syndrome Is Diagnosed

The key is to catch the abnormal rhythm and link it to your symptoms.

• Electrocardiogram (ECG) – a resting electrocardiogram (ECG) may show a slow rate, pauses or the tachy-brady pattern if present at the time.
• 24-hour Holter monitor – a 24-hour Holter monitor, or a 7-day or patch recording for less frequent symptoms, records the heart during normal life and links pauses or slow rhythms to symptoms noted in your diary.
• Implantable loop recorder – for very infrequent but important symptoms such as unexplained fainting, a small device placed under the skin can monitor for months.
• Echocardiogram – an ultrasound scan of the heart to check its structure and pumping strength.
• Blood tests – thyroid function and electrolytes to find reversible causes.
• Medication review – to identify drugs that may be slowing the heart.

Treatment Options

Treatment depends on symptoms and the pattern of rhythm disturbance.

• Reviewing medications – stopping or adjusting drugs that slow the heart may be enough in some cases.
• Treating reversible causes – such as an underactive thyroid or electrolyte imbalance.
• Permanent pacemaker – the main treatment for symptomatic sick sinus syndrome. A pacemaker is a small device implanted under the skin below the collarbone that monitors the heartbeat and gently paces the heart when it runs too slowly or pauses. Our cardiac pacemakers and devices service explains what implantation involves.
• Managing the fast episodes – in tachy-brady syndrome, medication or anticoagulants (blood thinners) may be needed for atrial fibrillation, and a pacemaker often allows these to be used safely without causing dangerous slowing.

Once a pacemaker is fitted, most people find their fatigue, dizziness and fainting improve.

Living With Sick Sinus Syndrome

With appropriate treatment, most people lead full and active lives. If you have a pacemaker, you will have regular device checks, and you can return to normal activities, exercise and travel. Keep taking any medication as prescribed, attend follow-up appointments, and report new or worsening symptoms so your treatment can be adjusted.

When to See a Cardiologist

See a cardiologist if you have unexplained fainting, recurrent dizziness, marked fatigue with a slow pulse, or palpitations that alternate with periods of feeling very slow. Because sick sinus syndrome can cause fainting and is readily treated with a pacemaker, early assessment is worthwhile. A specialist can confirm the diagnosis and decide whether a device is needed.

Frequently Asked Questions

Is sick sinus syndrome serious?

It is not usually immediately dangerous, but it can cause fainting that leads to injury, and the fatigue and breathlessness it produces affect quality of life. Once diagnosed, it is very treatable, most often with a pacemaker.

Does sick sinus syndrome always need a pacemaker?

No. A pacemaker is recommended when symptoms are clearly linked to the slow rhythm or pauses. If symptoms are mild, or a reversible cause such as a medication or thyroid problem is found and corrected, a pacemaker may not be needed.

What is tachy-brady syndrome?

It is a common form of sick sinus syndrome in which the heart swings between a slow rhythm and bursts of a fast rhythm such as atrial fibrillation. It can be tricky to treat, because medication for the fast episodes can worsen the slow ones – a pacemaker often solves this.

Can you live a normal life with sick sinus syndrome?

Yes. With treatment – usually a pacemaker when needed – most people lead full, active lives with normal exercise, work and travel. Regular device and cardiology follow-up keeps things running well.

What causes the sinus node to stop working properly?

Most often it is age-related scarring of the sinus node tissue. Coronary artery disease, high blood pressure, previous heart surgery, certain medications and thyroid problems can also contribute, and rarely it is inherited in younger people.