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Electrocardiograph

is an amplifier, a sensor, and a recorder

Electrocariograph is a measurement of

Voltage (vertical) in respect to time (horizontal)

1mm or 0.04 seconds

represents each smaller square on the EKG paper

25m/second

normal speed for an EKG tracing

What happens when the EKG is recorded at a faster speed

it will stretch

what happens if the EKG paper is to slow

causes it to compress

what does the sensitivity key control

how much gain of amplification the ECG will have

Normal sensitivity setting on the EKG

1

IF sensitivity is turned down to 1/2

the EKG will record all cardiac action at half its normal amplitude, deflections appear half as big, with waves half as tall

If sensitivity is increased to 2`

the EKG will record cardiac action at twice its normal amplitude, waves twice as tall

Each EKG tracing should begin with

A calibration check

how is a calibration check done

automatically by the EKG, and the mark it produces is called a standardization mark

The universal standard for the calibration check

1 millivolt of electrical activity should deflect the stylus exactly 10mm high

Diagnostic EKG is determined by

comparison between tracings of cardiac electrical activity

Deolarization

Discharge of electrical energy in the heart that typically causes contraction of the heart muscle cells

Repolarization

term for the heart muschle cells electrically "resetting" itself or returning to its polarized state.

Lead I records

electrical activity between LA and RA

Lead II records

electrical activity between LL and RA

Lead III records

electrical activity between LL and LA

aVR records

electrical activity between RA and halfway between LA and LL

aVL records

electrical activity between LA and halfway between RA and LL

aVF

electrical activity between LL and halfway between RA and LA

how can we determine the probable location of artifact voltages

by finding the commonalities within the views that record them

EKG records

cardiac voltage, and artifact voltages

4 artifacts

Somatic or muscle artifact AKA somatic tremor, AC interference (alternating current), wandering baseline, interrupted basline

somatic/muscle artifact voltages demonstrates

typically an erratic amplitude and frequency

cause of somatic artifact

pt movement, talking, or shaking due to cold or apprehension, vibration within the environment

AC interference demonstrates

typically a consistent amplitude and frequency

Cause of AC interference

improper grounding, presence of an electrical field, "cross talking" from crossed lead wires

Causes of wandering baseline

loose sensors, oily skin or lotion on skin, corroded sensors, or improper electorlyte

contductor of electrical impluses

electrolyte

why is electrolyte used to conduct electrical impulses

skin is a poor conductor

greatest disadvantage of using metal electrodes

cleaning the electrolyte paste off

how to obtain a good quality EKG

pt comfortable and relaxed, warm, pillow under head, adequate support for arms and legs

Chest lead

AKA precordial lead

Chest lead requires what

placement precise and proper positioning in order to obtain the most accurate results

V1 placed

at the 4th intercostal space on the right margin of the sternum

V2 placed

at the 4th intercostal space on the left margin of the sternum

V4 placed

at the 5th intercostal space on the left midclavicularline

V3 placed

halfway between V2 and V4

V5 placed

on the same horizontal level as V4, on the left anterior axillary line

V6 placed

on the same horizontal level as V4, on the midaxillary line

limb leads placed

RA, LA, RL, and LL

What limb lead is used as a ground

RL, electrical reference point only

Isoelectric line

AKA baseline, relatively straight line that is recorded in the absence of electrical activity

Waves/deflections

terms for variations from the baseline

P Wave

is the first deflection demostrated in a normal sinus rhythm

P wave represents

atrial depolarization

P wave followed by

the QRS complex

QRS Complex represents

ventricular depolarization

What follows QRS complex

T wave

T wave represents

cardiac repolarization, especially of the ventricles

What may follow the T wave

u wave

is the u wave normal

yes a normal occurrence but rare

standard limb leads

Leads I, II, III, they are bipolar and typically demonstrate upward, or positive deflections

aurgmented limb leads

aVR, aVF, aVL and are unipolar. They typically demonstrate downward of negative deflections

Chest leads

record activity froma central point within the heart looking out at one of 6 designated leads called V or C leads they record in sequence from right (V1) to left (V6)

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