Electrocardiogram Flashcards
What cardiac and extra cardiac abnormalities cause abnormal rhythm?
-stress
-fever
-toxicity (nutritional or pharmacological)
-low or high blood pressure
-hyperthyroid
-hypothyroid
-anemia
-heart failure
-shock
Consequences of arrhythmia
-dizziness
-syncope
-fatigue
-chest
-pain
-sudden cardiac death
-cardiac remodeling over time
Beats per lifetime
-larger animals often live longer but they also have low heart rates
-In general all animals seemed to fall within the same amount of beats/lifetime just takes different species different amounts of time to get there
P wave
-atria depolarize (contraction)
QRS wave
-ventricles depolarize
T wave
-ventricles repolarize (relax)
RR interval
-used to measure the heart rate (1 cardiac cycle)
PR interval
-time for atria to depolarize and excitation to travel to purkinje fibers
PR segment
-time between atrial and ventricular depolarization
QT interval
-time required for ventricles to depolarize and repolarize
ST interval
-time from the end of ventricular depolarization until repolarization is complete
ST segment
-time between ventricular depolarization and repolarization (time when ventricles are contracting)
Rules of ECG interpretation
1.a wave of depolarization travelling towards a positive electrode is a positive deflection in ECG trace
2. a wave of depolarization travelling away from a positive electrode is a negative deflection in the ECG trace
3. a wave of repolarization travelling towards a positive electrode is a negative deflection in ECG trace
4.A wave of repolarization traveling away from a positive electrode is a positive deflection in ECG trace
5. a wave of de- or repolarization traveling perpendicular to an electrode axis does not produce a deflection in ECG trace
6. a deflection amplitude depends on the position of the positive electrode relative to the mean electrical vector
7. the voltage amplitude is related directly to the mass of the tissue experiencing de- or repolarization
Einthoven’s Triangle
-Electrodes in shape of upside down triangle (RA, LA, LL)
-Lead I goes from RA (negative) to LA (positive)
-Lead II goes from RA (negative) to LL (positive)
-Lead III goes from LA (negative) to LL (positive)
Placing electrodes
-white to right
-smoke over fire
-green is ground
RA
-negative both directions
LA
-positive top
-negative bottom
LL
-positive both directions
Summation of leads
-Lead II= Lead I + Lead II
What degree angles are the leads at?
-Lead I at 0
-Lead II at +60 degrees
-Lead III at +120 degrees
-aVR at -150 degrees
-aVL at -30 degrees
-aVF at 90 +90 degrees