Question

What is P wave and Q wave?

Answer 1

In the context of an ECG (electrocardiogram), the P wave and Q wave refer to specific parts of the electrical activity of the heart, which is recorded as a graph on the ECG.

1. P Wave:

1. The P wave represents the depolarization (or electrical activation) of the atria (the upper chambers of the heart).
   

1. It is the first small, upward deflection on the ECG.
   

1. When the sinus node (the natural pacemaker of the heart) fires, it sends an electrical signal to the atria, causing them to contract and pump blood into the ventricles. This is captured as the P wave.
   

1. A normal P wave should be smooth and have a consistent, small upward shape.
   

2. Q Wave:

1. The Q wave is the first downward deflection in the QRS complex, which represents the electrical activity associated with the depolarization of the ventricles (the lower chambers of the heart).
   

1. It may be a small dip right before the large spike in the QRS complex.
   

1. Q waves are usually small or absent in a normal ECG.
   

1. Larger or deeper Q waves can indicate past damage to the heart muscle, such as from a heart attack (myocardial infarction), which can affect how electrical signals travel through the heart.
   

In summary:

1. The P wave reflects atrial depolarization.
   

1. The Q wave is the first part of the QRS complex and reflects the early stage of ventricular depolarization.
   

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