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Electrocardiogram: II

CARDIOVASCULAR PHYSIOLOGY

D. Late ventricular depolarization

As depolarization progresses over ventrides, vector shifts to hecome directed supenorly as well as to left, thus extending upward R wave in lead I and causing ncgatiye (downward) deflection (S wave) in lead aVF

Rir< ording axis of lead I thorizontal, right to left)

- Recording axis of lead aVF (vertical, downward)

Figurę 4.7 Cardiac Depolarization and Repolarization Part 2

ECG continued. As the apex of the ventricles contracts, a large    the venlricular walls, causing the S wave of the ECG tracing (panel

upward pos«tive deflection of the tracing yiełds the R wave of the D».

ECG (panel Q. Thcn the wavc of depolarization spreads through

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