Basic Cardiac Rhythm Interpretation || with 100% Verified Solutions.

P Wave correct answers Atrial Depolarization stimulated by the firing of the SA node. Evaluate: consistent appearance and 1:1 relationship with QRS complex. If not identical some, or all, may be atrial, but not SA node, in origin. IF 1 P-wave precedes QRS a heart block may be present. PR Interval correct answers Impulse traveling time from the atrium to the ventricles. Measure from the beginning of the P-wave to the beginning of the QRS complex. Evaluate: Duration & regularity of interval. If 0.20 seconds a conduction delay called an AV heart block is present. QRS complex correct answers Ventricular Depolarization Measure from beginning of Q-wave to end of S-wave where it returns to baseline. Evaluate: all complexes should look alike in the same lead. Normal Duration 0.12 seconds. Widening QRS complex suggests bundle branch block or other conduction delay. ST segment correct answers Represents the completion of ventricular depolarization and the beginning of ventricular repolarization. Along isoelectric line between the end of the QRS complex and the beginning of the T-wave. Depressed with myocardial ischemia. Elevated with myocardial infarction. T-wave correct answers Ventricular Repolarization Upstroke = absolute refractory period Downstroke = relative refractory period QT Interval correct answers Length of time it takes for ventricles to depolarize and depolarize. Measure from beginning of Q-wave to end of T-wave. Should be less than half of the R-R interval. Length 0.50 seconds is considered dangerously prolonged.