A patient's heart rate is regular at 68 beats per minute. The electrocardiogram (ECG) tracing shows P waves before every QRS complex. What is the likely pacemaker of the heart?
a. SA node
b. AV node
c. Bundle of His
d. Purkinje fibers
A
The SA node initiates electrical impulses at a rate of 60 to 100 per minute. When the ECG shows P waves before every QRS complex with a rate between 60 and 100 per minute, the rhythm is a normal sinus rhythm which is initiated by the SA node.
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