MFAC1523 Study Guide - Final Guide: Qrs Complex, Premature Atrial Contraction, Heart Block
1 Aug 2018
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Atrial impulse from atria through the av node, bundle of his, right and left bundle branches. Location from beginning of p wave to start of qrs complex. Duration 0. 06-0. 10s, or half of pr interval. Amplitude 5-30 mm high but differs for each lead used. Peaked/enlarged waves may indicate atrial hypertrophy or enlargement (associated with chronic obstructive pulmonary disorder, pulmonary emboli, valvular disease, heart failure) Inverted waves = retrograde or reverse conductions from the av node towards atria. Varying waves = impulse coming from different sites, as with a wandering pacemaker rhythm, irritable atrial tissue, or damage near the sa node. Absent waves = conduction by another route other than the sa node, as with a junctional or atrial fibrillation rhythm, or ventricular arrhythmia (impulse originated in the ventricles) Short intervals (<0. 12s) = impulse originated somewhere other than the sa node.
