Question

In ECG, a prolonged PR interval indicates

• A. Myocardial ischemia and hyperkalaemia
• B. Cardiac arrhythmia and hypokalaemia
• C. Coronary artery disease and rheumatic fever
• D. Hyperkalaemia and hypokalacmia

Answer 1

Answer: (C)

Coronary artery disease and rheumatic fever

The time from the beginning of the P wave (atrial depolarization) to the beginning of the QRS complex (ventricular depolarization) is the PR interval. This represents the time that it takes for the electrical impulse generated in the sinus node to travel through the atria and across the AV node to the ventricles. The normal PR interval is 0.12 to 0.20 seconds or 120 to 200 milliseconds (ms). A prolonged PR interval indicates delayed conduction of the SA nodal impulse to the ventricles and is called 1st degree AV block. A prolonged PR interval represents a delay in the time it takes for the signal to move across the atria at the top of the heart, which receive blood flowing in from the veins, into the ventricles at the bottom of the heart, which pump blood out into the arteries.