Premature Atrial Contraction (PAC) on Apple Watch ECG
Premature atrial contractions (PACs) are extra early beats that start in the heart’s upper chambers. They’re usually harmless but may be linked to things like caffeine, stress, pregnancy, or heart conditions.
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A Premature Atrial Contraction (PAC) is exactly what it sounds like—an early heartbeat that originates in the atria, the upper chambers of the heart. Normally, the heartbeat starts in the SA node, sending an electrical signal through the atria, down to the ventricles, causing the heart to contract and pump blood. In the case of a PAC, an extra signal fires off in the atria before the SA node sends its signal, leading to an extra, premature heartbeat
Most people might not even notice a PAC, but some might feel a brief fluttering sensation in their chest. While this can be alarming, PACs are generally harmless, especially if they occur infrequently.
How PACs Appear on an Apple Watch ECG
A normal heartbeat on an ECG consists of a P wave, a QRS complex, and a T wave. The P wave represents the electrical activity in the atria, the QRS complex shows the activity in the ventricles, and the T wave represents the recovery of the ventricles after contraction.
On an ECG, a PAC is identified by an early P wave that appears before the normal rhythm resumes. This early P wave might look different from the others because it originates from a different part of the atria. The QRS complex that follows the PAC is usually normal, but there may be a slight pause afterward as the heart resets to its regular rhythm.
In most cases, PACs are not dangerous and are common even in healthy individuals. They might occur more frequently due to stress, caffeine, or lack of sleep. However, if PACs happen often or cause significant symptoms like dizziness, shortness of breath, or chest pain, it's important to consult a doctor. Frequent PACs can sometimes be a sign of a more serious heart condition that needs to be addressed.
Are PACs Dangerous?
Conclusion
Premature Atrial Contractions are a common and usually harmless type of irregular heartbeat. They show up on an ECG as an early, different-looking P wave, followed by a normal QRS complex. While they are often not a cause for concern, it's always wise to seek medical advice if you experience frequent or troubling symptoms. Understanding PACs can help you stay informed about your heart health and take appropriate action if needed.