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6 Cards in this Set
- Front
- Back
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Define "lead" and "dipole"
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Lead is a pair of electrodes (exploring and reference), while a dipole of is a pair of electrical charges of equal magnitude but opposite sign and separated by a small distance.
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Describe basic vector principles
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Vectors have both magnitude and direction. If dipole is parallel to a lead and pointing toward the exploring electrode, a max positive voltage difference is detected. If a dipole is pointing toward an electrode but is not quite parallel, a positive sub maximal voltage is detected. If the dipole is perpendicular, no voltage difference is detected. Finally, if the dipole is pointing away from the electrode, negative voltage is detected.
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How does one lead record different dipoles
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The leads were designed so that the standard limb leads would give positive deflections in the situation of a normal axis of a heart, such that dipoles pointing down and to the right (orientation of left ventricle) would be positive on ECG reading.
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Determine electrical axis of the heart from frontal leads
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Using the hexaxial system, count the number of boxes under each spike for Lead I, II, and III. Then plot the numbers according to their location on the hexaxial system and draw a perpendicular line to the number allotted. Do this for all the leads and wherever they come together is the point directing the location of the dipole. Finally, draw a line from the center of the hex axial system to the point where all of the perpendicular lines intersect and determine the direction of the dipole during ventricular depolarization based off of the angles on the hexaxial system
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Understand the lead placement for a 12-lead ECG and why they are placed there.
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6 frontal leads - limbs and augmented voltage
6 chest leads ??? |
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Assess heart function based off of an ECG
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Electrical axis: If left axis is deviated, could be due to left ventricular hypertrophy; if right axis is deviated, could be due to right ventricular hypertrophy.
Arrangement of P, QRS, and T waves in relation to each other. For example: Sinus Arrythmias - Bradycardia/Tachycardia (low HR/High HR) separation of each set of P, QRS, and T groupings AV Block Type 1: prolonged PR interval AV Block Type II: not every P followed by a QRS AV Block Type III: no relationship between P and QRS waves Premature Ventricular Contractions (PVC): prolonged QRS go through ECG small group assignment for details of the 10 types of disorders that can be determined through ECG |
