A first look at the ECG Flashcards
What does the P-wave represent in a normal ECG?
Atrial depolarization, leading to atrial contraction.
What does the QRS complex represent in a normal ECG?
Ventricular depolarization, leading to ventricular contraction.
What does the T-wave represent in a normal ECG?
Ventricular repolarization, preparing for the next cardiac cycle.
What does the PR interval correspond to in an ECG?
The time from atrial depolarization (P wave) to the start of ventricular depolarization (QRS complex), representing conduction through the AV node.
What is the normal range for the PR interval?
120–200 ms (0.12–0.20 s)
What does the QRS complex duration correspond to?
The time taken for ventricular depolarization.
What is the normal range for the QRS complex duration?
<120 ms (0.12 s or less)
What does the QT interval correspond to?
The time from the start of ventricular depolarization (QRS) to the end of ventricular repolarization (T-wave).
What is the normal range for the QT interval?
≤440 ms in men, ≤460 ms in women, but varies with heart rate (corrected as QTc).
How do you measure heart rate from an ECG?
Count the number of large squares between two R-waves and use the formula:
Heart rate (bpm) = 300 / number of large squares between R waves
What is normal sinus rhythm (NSR)?
Regular rhythm originating from the SA node with a rate of 60–100 bpm, normal P waves, and a regular PR interval.
What is sinus tachycardia?
Heart rate >100 bpm with a normal rhythm, often due to stress, fever, or exercise.
What is sinus bradycardia?
Heart rate <60 bpm with a normal rhythm, which can occur in athletes or due to vagal stimulation.
What does STEMI stand for, and what does it indicate?
ST-Elevation Myocardial Infarction – complete blockage of a coronary artery, causing ST-segment elevation on ECG.
What does non-STEMI (NSTEMI) indicate?
Non-ST-Elevation Myocardial Infarction – partial blockage of a coronary artery, causing ST depression or T-wave inversion but no ST elevation.
