ECG Flashcards
ECG
provides record of how voltage btw two points on body surface changes with time as result of electrical events of cardiac cycle
P wave
atrial depolarization
Large horses: may see biphasic P wave DT low HR, large heart mass
Rapid inter-atrial transmission of electrical impulse (Bachmann’s Bundle) = simultaneous contraction of atria
PR Interval
conduction through AV node
QRS complex
ventricular depolarization, atrial repolarization occurs during this time but cannot see on ECG
ST Segment
time btw end of depolarization, start of repolarization
Elevation or depression (+/-0.2mV) indicator of myocardial ischemia, low CO, anemia, pericarditis, contusion
T wave
ventricular repolarization
Hyperkalemia: increase membrane conductance to K = shortens repolarization, produces T waves of large magnitude (spiked, point), short duration
Osborn/J wave
can be normal in certain breeds of dogs, assoc with hypothermia
Delta wave
re-entry circuit
Ta wave
atrial repolarization, often seen in large animals DT sufficient total atrial mass substantial enough to generate sufficient electromotive force
U wave
following completion of T waves, large animals/during electrolyte abnormalities (hypokalemia/calcemia), represents repol of M cells +/- Purkinje cells
Paper speed
25mm/sec: 1mm (small squares) = 40msec (0.04s), 5mm (large squares) = 200msec (0.2s)
RR method: 300/RR intervals in large squares
ECG Changes: hypokalemia
ST depression, flat/inverted T
U wave
ECG changes: hyperkalemia
flat or lost P wave
QRS widening
Tall, tented T wave
Prolonged PR interval
ECG changes: hypocalemcia
Prolonged ST segment
Prolonged QT interval
ECG changes: hypercalcemia
Shortened ST segment
Widened T wave
