Question

Mary is brought to the emergency department with a radial pulse of 70 beats per minute. An EKG is done and shows the following characteristics: 1) there are 70 normal P waves; 2) there are 70 normal QRS waves per minute; 3) the T waves are normal. Which of the following statements is most likely to be true?

Question options:
A)The cardiac depolarization wave is probably originating from an ectopic site in the left ventricle
B)The cardiac depolarization wave is probably originating from the right AV valve
C)The cardiac depolarization wave is probably originating from the AV bundle of His or bundle branches
D)The cardiac depolarization wave is probably originating from the SA node

Answer 1

Given the normal EKG with 70 P waves, QRS complexes, and T waves per minute, the cardiac depolarization wave is most likely originating from the SA node, as it is consistent with normal heart signaling and rhythm. D)The cardiac depolarization wave is probably originating from the SA node

Step-by-step explanation:

Mary has a radial pulse of 70 beats per minute, and her EKG shows 70 normal P waves, 70 normal QRS complexes, and normal T waves per minute. Based on the provided information about the electrocardiogram (ECG) and normal heart physiology, the cardiac depolarization wave is most likely originating from the SA node. The SA node is the natural pacemaker of the heart and initiates depolarization of the atria, leading to a P wave on an ECG. It sets the inherent rhythm of the heart under normal conditions. A normal QRS complex indicates that the ventricles are depolarizing properly, which typically occurs when the electrical signal follows the normal conduction pathway through the AV node and into the bundle of His or bundle branches. The presence of normal T waves suggests that ventricular repolarization is also normal.

Option D) 'The cardiac depolarization wave is probably originating from the SA node' is the correct answer because it is consistent with a normal EKG reading and a heart rate of 70 beats per minute. Misalignment of P waves, QRS complexes, or the presence of abnormal waveforms would suggest ectopic sites, conduction blockages, or other abnormalities.