When Is Sinus Bradycardia Considered a Cardiac Emergency?
Sinus bradycardia is considered a cardiac emergency when there is significant hemodynamic compromise associated with it. If the patient is hypotensive or having chest pain, diaphoresis, and problems mentating, among other things, the heart rate must be increased either electrically (by using a pacemaker) or pharmaceutically (using atropine or a catecholamine-like agent like epinephrine, norepinephrine, or dopamine).
ARRHYTHMIA RECOGNITION
Sinus Bradycardia
| Rate: | < 60 BPM |
| Regularity: | Regular |
| P wave:
Morphology: Upright in II, III, and aVF: |
Present
Same Yes |
| P:QRS ratio: | 1:1 |
| PR interval: | Normal, consistent |
| QRS width: | Normal or wide |
| Grouping: | None |
| Dropped beats: | None |
Most patients can tolerate heart rates between 50 and 60 BPM without too much difficulty. Sinus bradycardia typically becomes clinically significant when the heart rate drops below 50 BPM. This is because the slower the rate, the lower the cardiac output (remember: cardiac output = heart rate × stroke volume). Under normal circumstances, however, heart rates as slow as the low 40s may be normal for very well-conditioned athletes and in some patients during sleep.
DIFFERENTIAL DIAGNOSIS
Sinus Bradycardia