CRAT Study Guide
Lead I, II, and III are what kind of leads?
Bipolar (also frontal because they only show the front of the heart)
What makes Einthoven's Triangle?
Connecting leads I, II, and III at their ends
Causes of 60-cycle interference
Electrodes not properly applied, EKG machine not properly grounded, r by too many electrical devices nearby.
Pacemaker spikes with no P wave or QRS following it...
Failure to capture
No pacemaker spikes is...
Failure to sense
What does 60-cycle interference look like?
Fat highlighter marks on baseline
Which HB would you NOT need a pacemaker for?
First-degree AV block (prolonged PRI >0.20 seconds)
While in the resting state, myocytes are polarized and the interior of the cell becomes ________-ly charged
Negative
Failure to capture (loss of capture)
No P or QRS after the pacemaker spike
Gain
Normally set to 1
Pacemaker inhibition
Pacemaker doesn't work because it senses the heart is beating at or above the programmed rate
Undersensing
Pacemaker spikes in areas where they should not be (i.e. in the T wave, an ST segment, or on top of another QRS)
Causes of somatic tremor artifact
Patient keeps moving, Parkinson's disease
When cells contract, they become _______. (Negative or positive)
Positive
Causes of wandering baseline
Respiration or by lotion/sweat on the skin interfering with the signal
Lead I connects what?
Right arm to left arm
Lead II connects what?
Right arm to left leg
What is the natural pacemaker of the heart?
SA node
What is sensing?
The ability for the heart to sense and respond to the electrical activity of the heart
What is capture?
The pacemaker sends a stimulus to the heart which causes the heart to depolarize
Define intrinsic beats
The patient's own heart beat
How to fix 60-cycle interference
Unplug and re-plug somewhere else.
What causes leads reversed?
When the leads are placed on opposite limbs (i.e. left arm and right arm are switched)
A-V sequential pacing
When the pacemaker paces both the atrium and the ventricle
What does the P wave represent?
Atrial depolarization
What does the QRS complex represent?
Atrial repolarization and ventricular depolarization
Amplitude for one small box
?
Length of time for one small box
0.04 seconds
Normal QRS interval
0.11 or less
Normal PRI interval
0.12-0.20
3 types of pacemakers
1) single (either RA or RV) 2) dual chamber (RA and LV) 3) bi-ventricular (RV and LV --> Congestive Heart Failure)
Chart speed
25 mm/s
Memory method for calculating heart rate
300-150-100-75-60-50-43-37-33-30
Cardioversion vs. Defibrillation
Cardioversion: to change the heart rhythm (usually from SVT to sinus) Defibrillation: only used for pulseless VT and v-fib
Q wave indicates what?
Dead myocardial tissue. Always a negative deflection
Failure to sense
Lack of pacemaker spikes where they should have been. Battery can be dead.
Lead III connects what?
Left arm to left leg
How to fix somatic tremor artifact
Make sure leads are not placed over muscle and instead placed on bone, help patient relax, give a blanket.
