PAC ECG refers to the electrocardiogram (ECG) findings associated with Premature Atrial Contractions (PACs). PACs are extra heartbeats that originate in the upper chambers (atria) of the heart.
Understanding Premature Atrial Contractions (PACs)
- Origin: PACs start in the atria, which are the upper chambers of the heart.
- Nature: They are considered extra or premature heartbeats.
- Effect: Because the signal is early, the heart may not be full of blood when it contracts. This means less blood is pumped out.
PACs on ECG
The presence of PACs can be identified on an ECG by specific characteristics in the P wave and the overall rhythm:
| Feature | ECG Characteristics |
|---|---|
| P Wave | Premature, and may appear different (morphology) than the normal P waves because the electrical impulse originates from a different location in the atria |
| Rhythm | Underlying rhythm is usually regular but is interrupted by the premature beat. |
| QRS Complex | Usually normal, unless there is aberrant conduction (electrical signal does not follow the normal pathway) |
| Compensatory Pause | Often followed by a noncompensatory pause (the next normal beat occurs sooner than expected). |
In essence, a PAC ECG reveals irregularities in the heart's electrical activity that signify premature contractions originating from the atria.
