ECG PR Interval

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What is the PR interval measured from?

The beginning of the QRS complex to the end of the P wave

The end of the PR segment to the beginning of the QRS complex

The end of the P wave to the end of the QRS complex

The beginning of the P wave to the beginning of the QRS complex (correct)

What does the PR interval include physiologically?

Atrial depolarization and ventricular contraction

Atrial depolarization and the propagation of the impulse through the AV node (correct)

Ventricular depolarization and atrial relaxation

Ventricular depolarization and atrial contraction

What is the normal PR interval in adults?

0.05 s to 0.10 s

0.30 s to 0.40 s

0.20 s to 0.30 s

0.12 s to 0.20 s (correct)

What is the PR segment?

The part of the ECG that represents the propagation of the impulse through the AV node (D) Signup and view all the answers

What is the duration of one small square in the ECG?

0.04 s (C) Signup and view all the answers

In which direction does the cardiac impulse cause depolarization of the atria?

From right to left (B) Signup and view all the answers

What is the result of the impulse being conducted slowly in the AV node?

No electric change (A) Signup and view all the answers

Which part of the ventricular muscle is the first to be activated?

The interventricular septum (A) Signup and view all the answers

What is the direction of depolarization of the interventricular septum?

From left to right (A) Signup and view all the answers

What is generated by the depolarization of the left and right ventricular free walls?

The R-wave (A) Signup and view all the answers

Which of the following structures conducts the impulse quickly?

The bundle of His (C) Signup and view all the answers

What is the reason for no electric changes being recorded after the ventricles are completely depolarized?

The ventricles are in a plateau phase of action potential (A) Signup and view all the answers

What is the direction of ventricular muscle repolarization?

From epicardium to endocardium (A) Signup and view all the answers

Why are the recordings from all the bipolar limb leads similar to one another?

Because they all record positive P waves and positive T waves (C) Signup and view all the answers

What is the relationship between the algebraic sum of LII and the algebraic sum of L1 and LIII?

LII = L1 + LIII (C) Signup and view all the answers

What is the difference between the recordings from the augmented limb leads and the standard limb leads?

The recordings from the augmented limb leads are inverted (B) Signup and view all the answers

What is the significance of the similarity between the recordings from the three standard bipolar limb leads?

It makes it easier to diagnose cardiac arrhythmias (C) Signup and view all the answers

What is the direction of septum depolarization?

Left to right (B) Signup and view all the answers

What is the characteristic of QRS recordings in leads V1 and V2?

Mainly negative (D) Signup and view all the answers

Which leads overlie the anterolateral wall of the left ventricle?

V5 or V6 (A) Signup and view all the answers

What is the significance of a negative aVR wave in an ECG?

Correctly placed leads (B) Signup and view all the answers

What is the normal duration of the P wave in a normal heart?

0.08 to 0.10 seconds (A) Signup and view all the answers

Which of the following ECG components is occasionally present in normal persons?

U wave (C) Signup and view all the answers

What occurs during the PR segment?

Impulse traveling within the AV node (B) Signup and view all the answers

What is the significance of a P-R interval greater than 0.20 seconds?

AV conduction block (A) Signup and view all the answers

What is the normal duration of the QRS complex?

No more than 100 ms (C) Signup and view all the answers

What is the significance of a prolonged QRS complex?

Impaired conduction within the ventricles (D) Signup and view all the answers

What is the QRS complex representative of?

Ventricular depolarization (D) Signup and view all the answers

What is the effect of altering the site of the recording electrode on the QRS complex?

The shape changes (D) Signup and view all the answers

What is the characteristic of the T wave in relation to the QRS complex?

It has a longer duration (D) Signup and view all the answers

In which leads can T wave inversion be diagnosed?

Leads with large R waves (D) Signup and view all the answers

What is the significance of a prominent U wave?

It indicates underlying pathology or conditions affecting repolarization (B) Signup and view all the answers