Diagnosis of Heart Block
Accurate diagnosis of heart block is crucial for determining the degree of conduction delay and guiding appropriate treatment. The diagnosis of heart block is typically made using electrocardiographic testing and a thorough clinical evaluation. Since heart block can range from benign to potentially fatal. Early identification is essential to prevent complications such as syncope, heart failure, or sudden cardiac arrest.
The diagnostic process begins with a detailed medical history and physical examination. Healthcare providers assess symptoms like dizziness, fatigue, fainting, or palpitations. FUrthermore, consider risk factors such as existing heart disease, medication use, or prior cardiac surgery.
The primary tool for diagnosing heart block is the electrocardiogram (ECG or EKG). This non-invasive test records the electrical activity of the heart and can reveal delays or interruptions in signal conduction. Different patterns on the ECG help classify the heart block into first-, second-, or third-degree:
Diagnosis of Heart Block
First-degree AV block shows a consistently prolonged PR interval (greater than 200 milliseconds) with all atrial impulses still reaching the ventricles.
Doctors classify second-degree AV block into two types. In Mobitz Type I (Wenckebach), the PR interval gradually lengthens until a beat drops. In Mobitz Type II, the heart drops beats without the PR interval lengthening beforehand.
Third-degree (complete) AV block appears as complete dissociation between atrial and ventricular activity, with the atria and ventricles beating independently.
If doctors can’t clearly diagnose the problem or if symptoms come and go, they may use ambulatory ECG monitoring (like Holter monitoring or event recorders) to track abnormal rhythms over time. For patients with rare but severe symptoms, such as fainting, doctors may recommend implantable loop recorders.
Diagnosis of Heart Block
Additional testing may include blood work to check for electrolyte imbalances or markers of infection or inflammation, and imaging studies such as echocardiography to assess structural heart abnormalities. In cases where coronary artery disease is suspected, stress testing or coronary angiography may be performed.
In some patients, an electrophysiological study (EPS) is required. This invasive test maps the electrical pathways within the heart to pinpoint the location and severity of the conduction block, especially when considering a pacemaker or other intervention.
Timely and accurate diagnosis of heart block allows for tailored treatment, whether it involves monitoring, adjusting medications, or implanting a pacemaker to restore effective heart rhythm.
