Heart block is a condition that affects the electrical system of the heart. It occurs when the electrical signals that control the heartbeat are delayed or interrupted as they travel from the upper chambers of the heart to the lower chambers. This can result in a slower or irregular heartbeat. The term heart block can sound alarming, but it covers a wide range of conditions. Some forms are mild and require no treatment, while others need closer monitoring or intervention. Understanding what heart block is helps explain symptoms and guides appropriate assessment.
How the heart’s electrical system works
The heartbeat begins with an electrical signal generated in the heart’s natural pacemaker. This signal spreads through the upper chambers, causing them to contract, before passing through a specialised conduction pathway to the lower chambers. This coordinated sequence ensures that blood flows efficiently through the heart and out to the body. Heart block occurs when there is a delay or failure in this electrical conduction between the chambers.
Types of heart block
Heart block is usually divided into three main types, based on how much the electrical signal is affected.
First degree heart block
First degree heart block is the mildest form. The electrical signals reach the lower chambers, but more slowly than normal. This type often causes no symptoms and is frequently discovered incidentally on an ECG. In many cases, it does not progress or require treatment, but it may be monitored over time.
Second degree heart block
Second degree heart block occurs when some electrical signals fail to reach the lower chambers. This means that some heartbeats are missed. There are two recognised forms. One is often benign and may not cause symptoms. The other is more likely to progress and may cause dizziness, fatigue, or blackouts. Careful assessment is needed to determine the type and whether treatment is required.
Third degree heart block
Third degree heart block, also known as complete heart block, occurs when no electrical signals pass from the upper to the lower chambers. The lower chambers then rely on a much slower backup rhythm. This form of heart block often causes significant symptoms, including dizziness, breathlessness, or collapse. It usually requires treatment, most commonly with a pacemaker.
Causes of heart block
Heart block can occur for several reasons. In some people, it develops as part of the normal ageing process as the electrical system becomes less reliable over time. Other causes include previous heart attacks, heart surgery, inflammation of the heart, or underlying heart disease. Certain medications can also slow electrical conduction and contribute to heart block. In some cases, heart block is present from birth or associated with inherited conditions.
Symptoms of heart block
Symptoms depend on the severity of the block and how slow the heart rate becomes. Mild forms may cause no symptoms at all. More significant heart block can lead to dizziness, fatigue, breathlessness, reduced exercise tolerance, or blackouts. Symptoms may be intermittent, which is why heart block is sometimes difficult to detect without monitoring.
How heart block is diagnosed
Diagnosis usually begins with an ECG, which can show delays or interruptions in electrical conduction. Because heart block can come and go, longer term ECG monitoring is often used, particularly when symptoms are intermittent. Echocardiography may be performed to assess heart structure and function, as underlying heart disease influences management decisions.
Treatment options
Treatment depends on the type of heart block, symptoms, and underlying cause. Mild heart block may require no treatment beyond observation and review of medications. More advanced forms, particularly those causing symptoms, often require a pacemaker to maintain a safe and reliable heart rate. The decision to implant a pacemaker is based on evidence and clinical context rather than the ECG alone.
Living with heart block
Many people with heart block live normal lives, particularly when the condition is mild or has been appropriately treated. Those who require a pacemaker often experience improvement in symptoms and confidence once the heart rate is stabilised. Regular follow up ensures that the condition remains well managed.
Conclusion
It is sensible to seek assessment if there are symptoms such as unexplained dizziness, blackouts, or persistent fatigue, particularly if these occur with activity. If you have been told you have heart block or would like to understand ECG findings in more detail, you can book through this page to arrange an assessment and discuss the results in a clear and measured way. Heart block is a condition with many forms. Careful evaluation helps determine whether it is benign or requires treatment, allowing appropriate reassurance or intervention where needed.