Differential Diagnosis of Bradycardia and AV Block
| Diagnosis | ECG features |
|---|---|
| Sinus bradycardia | Constant PR interval <200ms QRS regular |
| Junctional bradycardia | P wave absent or position constant either after, immediately before or hidden in the QRS complex |
| First-degree AV block | Constant PR interval >200ms |
| Second-degree AV block, Mobitz type 1 | Progressively lengthening PR interval followed by dropped beat |
| Second-degree AV block, Mobitz type 2 | Constant PR interval with dropped beats |
| Third-degree (complete) AV block | Relationship of P wave to QRS varies randomly |
AV, atrioventricular.