CH3 The Electrocardiograph Flashcards
How many wires are used on a 12-lead EKG
10
Leads
Covered wires that conduct the electrical impulse from the electrodes to the ECG machine
Electrodes
Small sensors placed on the skin to detect the electrical activity from the heart
Einthoven’s triangle
A triangle formed by 3 of the limb electrodes, the right arm, left arm, and left leg
Limb lead
An ECG lead placed on an arm or leg
Bipolar lead
A type of ECG lead that measures the flow of electrical current in both directions at the same time
Lead I
Right arm to left arm
Bipolar
Lead II
Right Arm to Left leg
Bipolar
Lead III
Left arm to Left Leg
Bipolar
Augmented leads
Normally small ECG lead tracing that are increases in size by the ECG machine in order to be interpreted
Unipolar leads
A type of ECG lead that measures the flow of electrical current in 1 direction only
aVR
Lead measures from heart to the right arm
Augmented unipolar lead
Usually negative deflection
aVL
Heart to Left arm
Augmented unipolar lead
aVF
Heart to Left leg
Augmented unipolar lead
Precordial lead
A type of lead placed on the chest in front of the heart;
Known as a V lead
V1 placement
Right sternum
4th intercostal space
V2 placement
Left sternum
4th intercostal space
V3 placement
Midway btw V2 and V4
V4 placement
Midclavicular line
5th intercostal space
V5 placement
In line with V4 At anterior axillary line
V6 placement
In line with V4 AND V5 at the mid-axillary line
Multichannel recorder
an ECG machine that monitors all 12 leads but records 3 leads at a time and switches leads automatically, recording each of the 4 sets of 3 leads
Can also be read in 2 sets of 6 leads
Input
Data entered into an ECG machine, usually through electrodes on the skin surface
Signal Processing
The process within the ECG machine that amplifies the electrical impulse and converts it to a mechanical action on the output display
Output display
The part of⁰ the ECG machine that displays the tracing for the electrical activity of the heart, usually inban electronic or printed form on a 12-lead machine
3 basic functions of an ECG
Input, signal processing, output display
Speed control
A control on the ECG machine that regulates how fast or slow the paper runs during the tracing
In what cause would you increase speed to 50 mm/sec
If patient has unusually rapid heart rate
Gain
A control on the ECG machine that increases or decreases the size of the deflections on the ECG tracing
Normal gain setting for an ECG
10 mm/mV
What happens if you set gain to 20mm/mV
The waveform gets taller
Artifact
Unwanted marks on the ECG tracing causes by activity other than the hearts electrical activity
Normal setting for hertz on an ECG
40-50 Hz
What does a lead selector do
Allows you to run each lead individually
1mm equals how many secs in 25mm/sec ECG tracing?
0.04 secs
1 mm on a 10mm/mV tracing?
0.01 mV
300 method
Count large boxes from R to R
Calculate 300 ÷ (#large boxes)
1500 method
Count # small boxes
Calculate 1500 ÷ (#small boxes)
6-second method
Identify 6-sec section of tracing
Count # complete complexes seen in 1 6-sec interval
Multiply # of complexes by 10
