#1
Which ECG wave corresponds to ventricular depolarization?
QRS complex
ExplanationRepresents ventricular depolarization as electrical impulse spreads through the ventricles.
#2
What is the normal range for the PR interval duration in milliseconds (ms)?
0.12 - 0.20 ms
ExplanationNormal time interval representing the delay in impulse conduction from atria to ventricles.
#3
What does the T wave represent on an ECG?
Ventricular repolarization
ExplanationRepolarization of the ventricles following depolarization, seen as the T wave.
#4
What is the normal duration of the QRS complex in milliseconds (ms)?
0.04 - 0.10 ms
ExplanationDuration of ventricular depolarization, representing the time it takes for ventricular contraction.
#5
Which segment of the ECG represents the duration of ventricular depolarization?
QRS complex
ExplanationRepresents the depolarization of the ventricles as electrical impulse spreads through them.
#6
What is the normal heart rate range in beats per minute (bpm) for adults at rest?
60-80 bpm
ExplanationTypical resting heart rate range for adults, reflecting the rate of electrical impulses generated by the sinoatrial node.
#7
Which of the following represents the correct sequence of cardiac electrical conduction?
SA node, AV node, Bundle of His, Purkinje fibers
ExplanationSequential activation of cardiac conduction system from initiation to ventricular depolarization.
#8
What does a prolonged PR interval on an ECG indicate?
Delayed conduction through the AV node
ExplanationSlowed conduction from atria to ventricles, often indicating AV nodal pathology.
#9
In a normal ECG, which segment represents the duration of ventricular repolarization?
QT interval
ExplanationThe time from the start of ventricular depolarization to completion of ventricular repolarization.
#10
Which ECG lead provides the best view of the lateral wall of the left ventricle?
Lead V6
ExplanationOffers a view of the lateral wall of the left ventricle, aiding in diagnosis of lateral myocardial infarctions.
#11
Which electrolyte imbalance is most likely to cause a prolonged QT interval on an ECG?
Hypokalemia
ExplanationDecreased potassium levels affecting cardiac repolarization, lengthening QT interval.
#12
What does a U wave represent on an ECG?
Ventricular repolarization
ExplanationRepresents late ventricular repolarization, often seen after T wave.
#13
What does ST elevation in leads II, III, and aVF typically indicate?
Acute myocardial infarction (AMI) involving the inferior wall of the heart
ExplanationIndicates myocardial injury or infarction involving the inferior wall of the heart.
#14
What is the most common cause of peaked T waves on an ECG?
Hyperkalemia
ExplanationElevated potassium levels leading to rapid repolarization, manifesting as peaked T waves.
#15
In an ECG, what does an absence of P waves indicate?
Atrial fibrillation
ExplanationA lack of coordinated atrial depolarization, common in atrial fibrillation.
#16
What is the most common cause of a widened QRS complex on an ECG?
Right bundle branch block
ExplanationImpaired conduction through the right bundle branch, delaying ventricular depolarization.
#17
Which condition is commonly associated with a 'delta wave' on an ECG?
Wolff-Parkinson-White syndrome
ExplanationAccessory pathway between atria and ventricles causing early ventricular depolarization.
#18
In an ECG, which wave represents atrial repolarization?
U wave
ExplanationRepresents late repolarization of the Purkinje fibers and possibly the papillary muscles.