Heart Block and Pacemakers
Heart block and pacemakers overview
Each heartbeat begins with an electrical signal in the upper chambers (the atria). The signal travels through a junction called the atrioventricular (AV) node to the lower chambers (the ventricles), which pump blood. In heart block, also called AV block, this signal is delayed or fails to get through. The heart may then beat too slowly or skip beats.
Types of heart block
- First-degree block: every signal gets through, but slowly. It is usually found on an ECG, causes no symptoms and rarely needs treatment.
- Second-degree block, Mobitz type 1 (Wenckebach): the delay gets longer with each beat until one is dropped. It is often benign, particularly in fit young people.
- Second-degree block, Mobitz type 2: beats are dropped suddenly. It is more likely to progress and often needs a pacemaker.
- Third-degree (complete) block: no signals pass between the atria and ventricles. The ventricles beat slowly on their own, and this needs urgent assessment and a pacemaker.
Heart block symptoms and signs
Symptoms depend on how slow the heart becomes and how often beats are missed. First-degree block usually has none.
Possible symptoms
Signs
A doctor may find a slow or irregular pulse. The diagnosis is made on an ECG.
Causes and risk factors of heart block
Heart block can be present from birth (congenital) or develop later.
Common causes
- age-related wear of the conduction system, the most common cause
- coronary artery disease and a previous heart attack
- medicines that slow conduction, such as beta-blockers, verapamil, diltiazem, digoxin and some antiarrhythmics
- heart muscle disease (cardiomyopathy) and inflammation (see myocarditis)
- high vagal tone in very fit people, particularly at night
- infection, including Lyme disease, and some inflammatory conditions such as sarcoidosis
- cardiac surgery or procedures that affect the conduction system
- high potassium levels or an underactive thyroid
Reversible causes
Some heart block improves once the cause is treated, such as stopping a medicine, correcting a blood chemical or treating infection. These are checked first.
When to see a doctor about heart block
Call 999 if you faint, have severe chest pain, severe breathlessness, or collapse.
Arrange a prompt assessment if you have:
- a slow pulse with dizziness, tiredness or breathlessness
- fainting or near-fainting, particularly without warning or during exercise
- an ECG that shows heart block, or a letter that mentions it
- started a heart-rate-lowering medicine and feel unwell
How heart block is diagnosed
The diagnosis is made on an ECG, which shows how the atria and ventricles are communicating.
1. ECG
A 12-lead ECG can show the type of block. An ECG report can be arranged from anywhere in the UK.
2. Longer rhythm monitoring
Heart block may come and go, so longer recordings are often needed, from 24 hours up to several weeks. See nationwide cardiac monitoring.
3. Echocardiogram and other tests
An echocardiogram checks the heart muscle and valves. Blood tests, a review of medicines and, in selected people, an exercise test or cardiac MRI look for the cause.
Heart block treatment options
Treatment depends on the type of block, the symptoms and the risk.
1. No treatment or observation
First-degree block and Mobitz type 1 block without symptoms usually need only a periodic check.
2. Treating the cause
Medicines are reviewed and changed if they are responsible. Blood chemistry, thyroid problems and infection are treated.
3. Pacemaker
A pacemaker is recommended for symptomatic heart block, and for Mobitz type 2 or complete heart block, even without symptoms. It is a small device placed under the skin below the collarbone, with one or two thin wires that carry signals to the heart. The procedure usually takes about an hour under local anaesthetic, and most people go home within a day. Pacemaker implantation is performed in specialist hospitals. A consultation can review your ECG and monitoring and help you reach the right team.
Living with heart block or a pacemaker
Most people with a pacemaker return to their normal activities within a few weeks.
After a pacemaker
- Keep the wound clean and dry, and avoid heavy lifting with the arm on the device side for the time your team advises.
- Attend regular device checks.
- Keep a mobile phone about 15 cm from the device and avoid leaning over running car engines or strong magnets.
- Tell airport staff and any medical team about the device. MRI scans may be possible with modern devices, but need planning.
Driving
After a pacemaker is fitted, you must not drive a car or motorcycle for one week and must tell the DVLA if instructed. Different rules apply to bus, coach and lorry licences. See DVLA cardiac assessment.
Heart block prognosis and outlook
First-degree and Mobitz type 1 block are often harmless and need little more than monitoring. Higher grades of block can cause fainting or, rarely, life-threatening slow rhythms if left untreated, but a pacemaker is very effective in preventing this. With a pacemaker, most people have a normal life expectancy.
Heart block key facts
- Heart block means the electrical signal from the upper to the lower chambers is delayed or blocked.
- There are first, second and third degrees.
- It is diagnosed on an ECG, often with longer monitoring.
- A pacemaker is recommended for symptomatic or high-grade block.
Guidelines and sources
This page follows the 2021 ESC guidelines on cardiac pacing and cardiac resynchronisation therapy (Glikson et al., European Heart Journal 2021), NICE technology appraisal TA88 (2005) on dual-chamber pacemakers for symptomatic bradycardia due to sick sinus syndrome and/or atrioventricular block, DVLA guidance for medical professionals (Assessing fitness to drive: a guide for medical professionals) and NHS patient information.
Heart block questions and answers
Is heart block the same as a heart attack?
No. A heart attack is a blocked artery. Heart block is a delay in the heart’s electrical signal, although a heart attack can sometimes cause it.
Can heart block go away?
It can if it is caused by a medicine or a temporary problem. Block caused by age-related change is usually permanent.
Do I always need a pacemaker?
No. Mild forms need none. Pacemakers are for higher grades or symptoms.
Can I exercise with heart block?
Mild forms usually allow normal exercise. Your cardiologist will advise after assessment.
Can I have an ECG review privately?
Yes. Send your ECG for a professional ECG report or book a consultation.
Questions to ask your cardiologist about heart block
- What type of heart block do I have?
- What is causing it, and could a medicine be responsible?
- Do I need longer heart rhythm monitoring?
- Do I need a pacemaker, and how urgent is it?
- What activity or driving restrictions apply?
- How often will I need a check?
- If I need a pacemaker, which type is suitable for me, and what are the benefits and risks of the procedure?
- How long will I need to stay in hospital, and when can I return to work and normal activities?
- Will my pacemaker affect other tests or treatments, such as MRI scans, and what should I tell other doctors?
- Which symptoms should prompt urgent medical attention, and what should I do if I faint?
If you have a slow pulse, fainting episodes, or an ECG that shows heart block. You can book a video consultation or telephone consultation from anywhere in the UK, or a face to face consultation in Peterborough or Corby. An ECG report and heart rhythm monitoring can be arranged.
Book Your Heart Health Check Today
Personalised care
Your history, tests and questions are reviewed so the advice fits you.
Consultant-led care
Seen and assessed by a consultant cardiologist.
Clear
next steps
A written letter with your findings and next steps.
Advanced
diagnostics
Specialist in echo, stress echo, cardiac CT, MRI and heart failure.
Medically reviewed by Dr Salam Salloum, Consultant Cardiologist. Last reviewed: . This page is for general information and does not replace personal medical advice.