#1
Which part of the heart is responsible for initiating the electrical impulses in the cardiac cycle?
Sinoatrial (SA) node
ExplanationThe SA node initiates electrical impulses, serving as the heart's natural pacemaker.
#2
What is the main purpose of the QRS complex in an ECG waveform?
Ventricular depolarization
ExplanationThe QRS complex represents ventricular depolarization in the cardiac cycle.
#3
In which ECG lead is the R-wave amplitude typically the greatest?
Lead V4
ExplanationLead V4 usually has the greatest R-wave amplitude in a 12-lead ECG.
#4
What does the term 'PR interval' measure on an ECG?
Time from the start of atrial depolarization to the start of ventricular depolarization
ExplanationThe PR interval measures the time from the start of atrial depolarization to the start of ventricular depolarization in an ECG.
#5
What is the significance of the ST segment in an ECG waveform?
Represents the time between ventricular depolarization and repolarization
ExplanationThe ST segment represents the time between ventricular depolarization and repolarization in an ECG waveform.
#6
What does the P-wave represent in an ECG waveform?
Atrial depolarization
ExplanationThe P-wave signifies the depolarization of the atria during the ECG.
#7
Which lead in a 12-lead ECG is commonly associated with the lateral wall of the heart?
Lead V6
ExplanationLead V6 is often linked to the lateral wall of the heart in a 12-lead ECG.
#8
Which electrolyte imbalance is associated with a prolonged QT interval on an ECG?
Hypokalemia
ExplanationHypokalemia is linked to a prolonged QT interval in an ECG.
#9
What does the term 'ST-segment elevation' typically indicate in an ECG?
Myocardial infarction
ExplanationST-segment elevation often signifies myocardial infarction in an ECG.
#10
What is the approximate normal heart rate range for adults at rest?
60-90 beats per minute
ExplanationThe normal heart rate range for adults at rest is 60-90 beats per minute.
#11
Which condition is characterized by the absence of P-waves in an ECG, with irregular and chaotic ventricular activity?
Ventricular fibrillation
ExplanationVentricular fibrillation is marked by the absence of P-waves and chaotic ventricular activity in an ECG.
#12
What is the normal duration of the PR interval in milliseconds?
120-200 ms
ExplanationThe PR interval's normal duration is 120-200 milliseconds in an ECG.
#13
In a 12-lead ECG, which leads are considered precordial leads?
Leads V1-V6
ExplanationLeads V1-V6 are precordial leads used to assess the heart's anterior, lateral, and posterior walls.
#14
Which lead is commonly used to assess the heart's electrical axis in an ECG?
Lead aVF
ExplanationLead aVF is commonly used to evaluate the heart's electrical axis in an ECG.
#15
What is the primary purpose of the T-wave in an ECG waveform?
Ventricular repolarization
ExplanationThe T-wave represents ventricular repolarization in the ECG.
#16
What does the term 'bundle branch block' refer to in an ECG?
Delayed or blocked conduction in the bundle branches
ExplanationBundle branch block indicates delayed or blocked conduction in the bundle branches of the heart's electrical system.
#17
Which segment of the ECG represents the time between ventricular depolarization and repolarization?
ST segment
ExplanationThe ST segment signifies the time between ventricular depolarization and repolarization in an ECG.