EKG Flashcards
What are some specific characteristics of cardiac muscle?
Excitability, Inherent Rhythmicity, Conductivity, Contractility
List the conduction pathway of the heart. (5 steps)
SA Node > AV Node > Bundle of His > Bundle Branches > Purkinje Fibers
Myocardial muscle is thinner in ____ & larger in ____ ?
Thinner in atria, Larger in ventricles
What is myocardial muscle physiological function:
Generate Force
The “pacemaker” consists of what & what is it’s purpose?
SA Node & AV Node. Function is to initiate/control the heart beat.
In myocardial tissue, which locations are responsible for coordinating conduction?
Bundle of His, R & L bundle branches, and Branches of the purkinje fibers.
ECG / EKG can be used as a non-invasive procedure to:
1.) heart rate & regularity of beats
2.) size & position of chambers
3.) detect damage & pharmacology effects
How many leads & electrodes are used in an EKG?
12 Leads & 10 Electrodes
What does the “Axis” of an EKG reference?
The direction of depolarization as it moves through the heart.
What does Unifocal reference?
One location, with normal P-waves (similar amplitudes) & SA node conduction.
What does Multifocal reference?
Many locations (PVC, PAC, etc…) with different size & shaped p-waves.
What is Ischemia?
Low/Decreased blood flow to the heart.
What does Infarction mean?
Injury/Necrosis to the heart muscle due to ischemia.
What is the strategy of a 12-lead EKG?
Rate, Rhythm, Ischemia/Infarction, Axis, Hypertrophy
On an EKG readout, one large 5mm x 5mm box represents how much time & how much amplitude?
0.2 seconds (200ms) & 0.5 mV amplitude
On an EKG readout, one small 1mm x 1mm box represents how much time & how much amplitude?
40 ms & 0.1 mV amplitude
What does the “P” wave indicate on the cardiac cycle?
Atrial Depolarization
What does the “QRS” complex indicate on the cardiac cycle?
Ventricular Depolarization
What does the “T” wave indicate on the cardiac cycle?
Ventricular Repolarization
What is a normal distance or time for a P-Wave?
< 3mm wide (or) < 0.12 sec
During the P-Wave, what does the PR interval refer to & what is a normal value?
PR Interval: SA to AV node conduction.
Normal Value: < 0.12 to 0.20 sec (3-5 small boxes).
What does an abnormal PR interval indicate?
Type 1 AV Block, meaning slowed conduction from SA node to AV node.
During the Q-Wave deflection should be (positive or negative) & why?
Negative deflection due to flow of electrical activity from L to R.
What is a normal value & amplitude for the QRS complex?
Time/width should be shorter than 0.12 sec (or 3 small boxes)
Amplitude less than 7 boxes (sum of V5 upward deflection & V1 downward deflection)
