University:
Camosun College
Course:
BIOL 252 | Pathophysiology for Nursing 1
Academic year:

2024
Views:

470

Pages:

3
Author:

Aysha A.

Vector 4: ECG Action Potential (AP) is formed in all cardiac cells, leading to an ECG. ECG Paper: Small square: 1mm. Time: 0.04s. Y-axis: 0.1mV. Large square: 5mm. Time: 0.2s. Y-axis: 0.5mV. Calibration: 25mm/s: Paper moves at this speed. 1mV on Y-axis (2 large squares). 25mm/s on X-axis. 5 large squares (or 25 small squares) = 1 second. Anatomy of Heart: Anterior surface: Primarily right ventricle (RV). Unipolar Leads Disadvantages: Very small potential difference. Problems cannot be narrowed down to particular ventricles. Augmentation: Short circuiting is induced, so the reference electrode becomes zero. Allows study of individual chamber behavior. Larger graphs obtained (all potential differences). Unipolar Leads: Used in ECG; reference electrode is made to have zero potential. 6 Limb Leads: Lead I, II, III, aVR, aVF, aVL. Chest Leads: Unipolar leads: V₁ to V₆. Pericardial Fluid/Pleural Air/Alveolar Air: Bad conductors of current. Central Wilson Terminal: Reference electrode for chest leads. Septal Leads: V₁ → Right 4th ICS (intercostal space), lateral sternal border. V₂ → Left 4th ICS, lateral sternal border. Anterior Leads: V₃ → Between V₂ & V₄. V₄ → Left 5th ICS, midclavicular line. Lateral Leads: V₅ → Left 5th ICS, anterior axillary line. V₆ → Left 5th ICS, midaxillary line.