Symptoms of Heart Block
The symptoms of heart block depend on the severity of the conduction abnormality and whether the disruption is intermittent or persistent. Recognising the symptoms of heart block is crucial for early diagnosis and timely intervention. Particularly in higher-degree blocks which may be life-threatening if left untreated.
First-degree heart block
In first-degree heart block, the symptoms are often absent. This form is usually discovered incidentally during routine ECGs or evaluations for unrelated issues. Because the electrical signals are only slowed (not blocked), most individuals with first-degree heart block lead normal lives without requiring treatment.
Second-degree heart block
Second-degree heart block presents more variability. In Mobitz Type I (Wenckebach), patients may remain asymptomatic or experience mild symptoms like light-headedness or fatigue due to occasional missed beats. In Mobitz Type II, the symptoms tend to be more pronounced and unpredictable. As the ventricles may fail to respond to some or many atrial impulses. Common symptoms include:
Dizziness or light-headedness
Palpitations or skipped heartbeats
Fatigue
Shortness of breath, especially during exertion
Mild chest discomfort
Third-degree (complete) heart block
Third-degree (complete) heart block is the most serious and typically causes significant symptoms due to the complete dissociation between atrial and ventricular contractions. The heart’s pumping efficiency is dramatically reduced. Leading to bradycardia (abnormally slow heart rate) and insufficient blood flow to vital organs. Symptoms often include:
Severe fatigue and weakness
Episodes of syncope (fainting)
Confusion or memory disturbances (especially in older adults)
Chest pain or discomfort
Sudden cardiac arrest (in extreme cases)
In some individuals, the symptoms can be subtle or come on gradually, making diagnosis more challenging. Symptoms may worsen over time if the underlying cause progresses or if other cardiac issues develop. Conditions such as atrial fibrillation or heart failure, develop concurrently.
For infants and young children with congenital heart block, signs may include poor feeding, lethargy, failure to thrive, or visible pauses in heart rhythm detected on examination. In utero, congenital block may lead to hydrops fetalis, a potentially fatal condition requiring urgent management.
Symptoms of Heart Block
Overall, the symptoms of heart block reflect the degree of electrical disruption and the heart’s compensatory ability. Recognising these symptoms—especially in the context of known risk factors or existing heart disease—is essential for initiating the right diagnostic workup and life-saving treatment.
