ECG Flashcards
Which of the following leads are considered bipolar limb leads in a standard 12-lead ECG?
A) aVR, aVL, aVF
B) I, II, III
C) V1, V2, V3
D) V3R, V4R
B) I, II, III
What is the main purpose of the Wilson central terminal in ECG lead placement?
A) To enhance the electrical activity from the limbs
B) To create a constant negative pole for unipolar leads
C) To provide a backup in case of lead failure
D) To record heart rate
B) To create a constant negative pole for unipolar leads
How does the positioning of the patient (sitting vs. supine) affect the ECG?
A) It does not affect the ECG.
B) It changes the lead’s electrical properties.
C) It alters the relationship of chest leads to the heart.
D) It only affects limb leads.
C) It alters the relationship of chest leads to the heart.
What can happen if a chest lead is placed in an interspace that is too high or too low?
A) The ECG will be unaffected.
B) The ECG waveform recorded will change.
C) It will cause a permanent heart condition.
D) It will only affect limb leads.
B) The ECG waveform recorded will change.
In which situations are right-sided chest leads (V3R and V4R) typically used?
A) Only in pediatric patients
B) To assess limb lead quality
C) To diagnose right ventricular infarction
D) In routine physical examinations
C) To diagnose right ventricular infarction
Why is consistency in lead placement important when recording serial ECGs?
A) To minimize patient discomfort
B) To ensure accurate heart rate measurement
C) To avoid significant changes in ECG patterns
D) To improve the speed of recording
C) To avoid significant changes in ECG patterns
What does the P wave in an ECG represent?
A) Ventricular repolarization
B) Atrial depolarization
C) Atrial repolarization
D) Ventricular depolarization
B) Atrial depolarization
Which component of the ECG reflects ventricular depolarization?
A) P wave
B) PR interval
C) QRS complex
D) T wave
C) QRS complex
What is the significance of the ST segment and T wave in the ECG waveform?
A) They indicate atrial contraction.
B) They reflect ventricular repolarization.
C) They show electrical activity of the AV node.
D) They are silent events with no clinical relevance.
B) They reflect ventricular repolarization.
What does the U wave represent in an ECG?
A) Atrial contraction
B) Ventricular depolarization
C) An electromechanical event related to ventricular relaxation
D) The electrical activity of the AV node
C) An electromechanical event related to ventricular relaxation
Why is the depolarization of the sinus node not recorded in an ECG?
A) It occurs after the P wave.
B) Its voltage signal is too small to be detected.
C) It is not relevant to cardiac function.
D) It occurs during the QRS complex.
B) Its voltage signal is too small to be detected.
What occurs during the PR interval that is electrocardiographically silent?
A) Atrial depolarization
B) Ventricular repolarization
C) Electrical activity of the AV node and His-Purkinje system
D) Sinus node depolarization
C) Electrical activity of the AV node and His-Purkinje system
What primarily causes the P wave in an ECG?
A) Depolarization of the ventricles
B) Voltage gradients during atrial depolarization
C) Repolarization of the atria
D) Electrical activity of the AV node
B
How is the shape and duration of the P wave determined?
A) By the position of the ECG electrodes
B) By the sequence and timing of atrial depolarization
C) By the overall heart rate
D) By the strength of the heart muscle
B
In which leads is the P wave typically upright or positive?
A) I, II, aVR
B) aVL, V3 to V6
C) III, aVF
D) Both A and B
D
What happens to the P wave configuration if the ectopic atrial focus is located far from the sinus node?
A) It remains unchanged.
B) It resembles the normal sinus P wave.
C) It becomes more abnormal in shape.
D) It disappears entirely.
C
If an impulse arises from the inferior portion of the atrium, how will the P waves appear in leads II, III, and aVF?
A) Upright
B) Biphasic
C) Inverted
D) Flattened
C
What effect can atrial hypertrophy and/or dilation have on the P wave?
A) It can cause the P wave to disappear.
B) It can affect the amplitude and duration of the P wave.
C) It has no effect on the P wave.
D) It causes the P wave to become biphasic in all leads.
B
What does the PR interval encompass in an ECG?
A) Only the P wave
B) The P wave and the QRS complex
C) The P wave and the PR segment
D) The QRS complex and the T wave
C
What components make up the PR segment?
A) Atrial repolarization and depolarization of the AV junction
B) Ventricular repolarization and depolarization
C) Sinus node activity and atrial contraction
D) Atrial depolarization and ventricular contraction
A
Which of the following factors can lead to prolonged AV conduction and an increased PR interval?
A) Decreased vagal tone
B) Increased sympathetic tone
C) Digitalis and β-adrenergic blocking agents
D) High potassium levels
C
What occurs in cases of complete AV block regarding the P waves and QRS complexes?
A) They become identical.
B) The P waves are dissociated from the QRS complexes.
C) The QRS complexes disappear.
D) The P waves merge with the QRS complexes.
B
How does the PR interval change in the presence of an AV nodal bypass tract, such as in the Wolff-Parkinson-White pattern?
A) It is prolonged.
B) It becomes absent.
C) It is shortened.
D) It remains unchanged.
C
Which of the following can lead to a shortened PR interval?
A) Increased vagal tone
B) AV nodal bypass tract
C) Ischemia
D) Inflammatory diseases
B
What does the QRS complex primarily reflect in an ECG?
A) Atrial depolarization
B) Ventricular depolarization
C) Atrial repolarization
D) Ventricular repolarization
B
Which part of the ventricle is the first to be depolarized?
A) Right ventricle
B) Left ventricle
C) Interventricular septum
D) Apex of the heart
C
In which leads is the QRS complex typically upright or positive due to left ventricular dominance?
A) I, V5, V6
B) aVR, V1
C) II, III, aVF
D) I, II, III
A
What abnormality can lead to the identification of right ventricular depolarization on the ECG?
A) Left bundle branch block
B) Right bundle branch block
C) Normal sinus rhythm
D) Ventricular ectopic beats
B
How does the QRS complex change in shape and duration with bundle branch blocks?
A) It remains unchanged.
B) It is prolonged and may show significant changes in configuration.
C) It becomes biphasic.
D) It is always inverted.
B
What can cause intraventricular conduction abnormalities without a change in QRS configuration?
A) Bundle branch blocks
B) Fascicular blocks
C) Cardioactive drugs and increased extracellular potassium
D) Ventricular ectopic beats
C
What do fascicular blocks reflect in the conduction system?
A) Conduction slowing in the right bundle branch
B) Conduction slowing in one fascicle of the left bundle
C) Complete blockage of the AV node
D) Normal conduction through the ventricles
B
How do fascicular blocks affect the QRS complex?
A) They have no effect on the QRS complex.
B) They alter the initial portion of the QRS complex and the electrical axis.
C) They only increase the duration of the QRS complex.
D) They solely indicate the presence of a previous myocardial infarction.
B
What is true about right bundle branch block (RBBB)?
A) It affects the initial portion of the QRS complex.
B) It obscures the diagnosis of previous myocardial infarction.
C) It allows for appreciation of previous MI changes in the ECG.
D) It mimics left ventricular hypertrophy changes.
C