What does atrial depolarization look like on an ECG?
Atrial and ventricular depolarization and repolarization are represented on the ECG as a series of waves: the P wave followed by the QRS complex and the T wave. The first deflection is the P wave associated with right and left atrial depolarization.
Which wave in ECG represents atrial depolarization?
P wave
P wave in ECG deflection represents atrial depolarization. Atrial repolarization occurs during ventricular depolarization and is obscured.
What indicates atrial depolarization?
The P wave indicates atrial depolarization. The P wave occurs when the sinus node, also known as the sinoatrial node, creates an action potential that depolarizes the atria.
What are Q waves on ECG?
INTRODUCTION. By definition, a Q wave on the electrocardiogram (ECG) is an initially negative deflection of the QRS complex. Technically, a Q wave indicates that the net direction of early ventricular depolarization (QRS) electrical forces projects toward the negative pole of the lead axis in question.
What is depolarization and repolarization in ECG?
A wave of depolarization traveling toward a positive electrode results in a positive deflection in the ECG trace. A wave of depolarization traveling away from a positive electrode results in a negative deflection. A wave of repolarization traveling toward a positive electrode results in a negative deflection.
Why is P wave positive in lead 2?
The normal P wave reflects these activation patterns. Thus, P waves are positive in lead II and usually in leads I, aVL, and aVF, reflecting the leftward and inferior direction of activation during sinus rhythm. This corresponds to a mean frontal plane P wave axis of approximately 60 degrees.
What is QRS wave in ECG?
A combination of the Q wave, R wave and S wave, the “QRS complex” represents ventricular depolarization. This term can be confusing, as not all ECG leads contain all three of these waves; yet a “QRS complex” is said to be present regardless.
What is the heart doing during the T wave?
The T wave on the ECG (T-ECG) represents repolarization of the ventricular myocardium. Its morphology and duration are commonly used to diagnose pathology and assess risk of life-threatening ventricular arrhythmias.
What is atrial repolarization?
Atrial repolarization waves can simulate myocardial ischemia by causing ST segment elevation or depression depending upon the site of origin of the atrial impulse. Awareness and identification of pseudoinfarct patterns on ECGs is important to avoid unnecessary diagnostic interventions and treatment.
Why is R wave positive?
The R wave is very positive because early ventricular depolarization is largely directed toward this lead. The S wave is also present because the terminal depolarization of the upper wall of the left ventricle is directed away from aVF.