Approach to bradycardia: Clinical sciences

Bradycardia is typically defined as a heart rate below 60 beats per minute, or bpm, although in some instances it can be considered below 50 bpm. Bradycardia may originate from physiologic changes in vagal tone, pathologic changes to the cardiac conduction system, infectious causes, or medication effects.

The severity might range from completely asymptomatic to life-threatening, and based on 12-lead ECG findings, you can determine if the bradycardia is physiologic, or if it’s due to sinus or sinoatrial or SA node dysfunction, or even atrioventricular or AV node dysfunction.

Now, if a patient presents with bradycardia, you should first perform an ABCDE assessment to determine if they are unstable or stable. If they’re unstable and there’s a detectable pulse, follow the ACLS guidelines for Bradycardia with a Pulse.

First stabilize their airway, breathing, and circulation. Provide supplemental oxygen if they’re hypoxemic, to maintain oxygen saturation above 90%. Next, obtain IV access and put your patient on continuous vital sign monitoring including heart rate, blood pressure, and pulse oximetry.

Now let's go back to the ABCDE assessment and discuss the approach to a stable patient. First, perform a focused history and physical examination. Your patient may report exercise intolerance, lightheadedness, or even syncope, and some patients may experience ischemic-type chest pain or nausea.

Additionally, on a physical exam, cardiac auscultation and pulse palpation will reveal a slower than normal heart rate. Moreover, if the heart rate is below 60 beats per minute, you can diagnose bradycardia.

Here’s a clinical pearl! The typical definition of a normal heart rate is between 60 and 100 bpm. However, although technically anything below 60 bpm should be considered bradycardia, you may find it defined as below 50 bpm, since most patients with a heart rate in the 50s are actually asymptomatic and require no treatment.