Heart Block
What is It?
Heart block occurs when the electrical signals that tell the heart to contract are delayed or blocked between the upper chambers (atria) and lower chambers (ventricles). This results in a slow or irregular heartbeat. Heart block is classified into three degrees: first-degree (signals are delayed but all reach the ventricles), second-degree (some signals are blocked), and third-degree or complete heart block (no signals pass between atria and ventricles). Heart block is more common in older adults and may be present from birth (congenital) or develop later in life.
What are the symptoms?
Heart block may present in different ways depending on the severity. First-degree and milder forms often cause no symptoms. More significant heart block may cause fatigue, dizziness or lightheadedness, shortness of breath, palpitations, chest discomfort, or fainting episodes. Complete heart block may cause severe symptoms requiring urgent treatment.
What are the causes?
At One Heart Centre our cardiologists screen for all causes of heart block. Causes include:
- Age-related degeneration of the heart’s electrical conduction system.
- Coronary artery disease and previous heart attacks damaging the conduction system.
- Medications that slow the heart rate, such as beta-blockers, calcium channel blockers and digoxin.
- Infections such as Lyme disease and myocarditis.
- Congenital factors, heart surgery, infiltrative diseases such as sarcoidosis, and electrolyte imbalances.
How is it investigated?
An ECG is the most common method of diagnosing heart block. Your One Heart Centre cardiologist may also arrange ambulatory ECG monitoring over a period of time to thoroughly assess your conduction system. Additional testing with exercise stress testing, echocardiogram, or cardiac MRI may also be required. An electrophysiology (EP) study may be used to determine the exact location and severity of the block in selected cases. Blood tests screen for underlying causes.
What are the treatments?
At One Heart Centre our cardiologists have post-fellowship training in managing heart block and will provide a personalised treatment plan for your heart block. Treatment options include:
- Surveillance: First-degree and asymptomatic Mobitz type I heart block often require no treatment, only periodic monitoring.
- Medication review: Stopping or reducing medications that may be causing or worsening the block.
- Treating underlying causes: Addressing infections, ischaemia or electrolyte imbalances.
- Pacemaker implantation: Required for high-grade (Mobitz II or complete) heart block to correct the rhythm abnormality and prevent symptoms or sudden collapse.