Electrocardiography Quiz

ECG Characteristics

• ST segment elevation is the most commonly associated ECG characteristic with myocardial infarction.
• Leads II, III, and aVF are most likely to show inverted T waves in ischemia.

Leads and ECG Components

• Leads V1-V6 are associated with anterior myocardial infarction.
• A standard 12-lead ECG includes the following leads: I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6.
• The PR interval represents the time taken for atrial depolarization and AV node delay.
• The QT interval represents the time taken for ventricular depolarization and repolarization.

Frontal Plane and Heart Rate

• Leads I, II, III, aVR, aVL, and aVF provide six viewpoints of cardiac activity in the frontal plane.
• The normal range of the QRS interval is 0.08-0.10 seconds.
• The heart rate can be estimated using the box method on an ECG by counting the number of large squares between two successive R-waves.

Heart Block and Bundle Branch Block

• The AV node is responsible for setting the heart rate if the SA node fails.
• A narrow QT interval indicates a shorter time taken for ventricular depolarization and repolarization.
• A prolonged PR interval is characteristic of first-degree heart block.
• The characteristic feature of right bundle branch block (RBBB) on an ECG is a widened S wave in lead I and a widened R wave in lead V1.

ECG Components

• The P wave represents atrial depolarization.
• The QRS complex represents ventricular depolarization.
• The PR interval signifies the time taken for atrial depolarization and AV node delay.
• The T wave represents ventricular repolarization.

Heart Rate and Myocardial Infarction

• The normal adult resting heart rate is 60-100 beats per minute.
• ST segment elevation on an ECG indicates acute myocardial infarction (MI).
• A 12-lead ECG can record electrical activity in both the frontal and horizontal planes of the heart.

Intervals and Ranges

• The normal range for the PR interval is 0.12-0.20 seconds.