Understanding Bradycardia: Causes, Diagnosis, and Management

Exploring Bradycardia

Bradycardia is an abnormal heart rhythm characterized by a slow heartbeat, typically fewer than 60 beats per minute, and occasionally as slow as 40 beats per minute. While some individuals, particularly athletes, may naturally have a lower resting heart rate, bradycardia becomes a concern when patients exhibit signs of cardiogenic shock. This condition demands vigilant monitoring and appropriate intervention.

Determining the Cause

As with tachycardias, it is essential to determine whether the cause of bradycardia is extrinsic or intrinsic. Extrinsic factors may include poisoning, hypothermia, or certain medications, while intrinsic factors could involve blockages at the atrioventricular node. The definitive diagnosis can only be established through an ECG analysis of the rhythm.

Managing Bradycardia

Management strategies for bradycardia depend on the underlying cause:

• Extrinsic Causes: In cases where bradycardia results from extrinsic factors, such as excessive vagal tone, Atropine administration at 500 micrograms may be effective. Repeat doses of up to three milligrams may be administered at three to five-minute intervals, based on the patient's response.
• Intrinsic Causes: Bradycardia arising from intrinsic factors may require more advanced intervention. In cases like third-degree heart block, transthoracic pacing using a defibrillator in pacing mode becomes necessary. The rate is typically set to 60 beats per minute with milliamps at 70. Milliamp voltage is adjusted until QRS capture is achieved. An increase of up to five milliamps is made to maintain capture while gradually increasing the rate to improve the patient's condition. Sedation with Midazolam may be considered to alleviate discomfort.

Fist Pacing as a Temporary Measure

In cases of cardiogenic shock and unavailability of a defibrillator, fist pacing can serve as a temporary measure. This technique involves delivering rhythmic thumps to the sternum until appropriate pacing can be established. It's important to note that in patients with heart transplants, where the vagus nerve is disconnected, Atropine is not indicated for bradycardia management.

By understanding the causes and tailored management approaches for bradycardia, healthcare providers can ensure effective treatment and improved patient outcomes.