Cardiovascular system/ECG Flashcards
where are the ECG leads placed on the patient?
white: right forelimb
black: left forelimb
red: left hindlimb
green: right hindlimb
what does the P wave represent?
depolarization of the atria
what does an enlarged P wave mean?
atrial enlargement
what does the P-R interval represent?
atrial depolarization and conduction through the AV node
what does P-R interval prolongation mean?
1st degree AV block
what does the QRS complex represent?
depolarization of ventricles
what does a wider QRS complex mean?
abnormality
could be caused by hyperkalemia or ventricular hypertrophy
what does the T wave represent?
ventricular repolarization
what is the Q-T interval?
begins at the start of the QRS complex and finishes at the end of the T-wave
what does the Q-T interval represent?
time for ventricles to depolarize and then repolarize
sinus arrhythmia
normal HR with an increase on inspiration and a decrease on expiration
atrial fibrillation
lack of P waves, can have rates up to 600 bpm
represents severe heart disease with atrial enlargment
ventricular tachycardia
life-threatening, wide/bizarre QRS complexes without P waves and with tachycardia (HR > 180bpm)
shockable rhythm
ventricular premature contractions (VPCs)
premature P waves, many possible causes (electrolyte abnormalities, systemic disease, cardiac disease)
what do atria contain?
auricles
blind pouches (“ear flaps”)
which side is the tricuspid valve on?
right side
which side is the mitral valve on?
left side
cardiac cycle
1 cycle of atrial and ventricular contraction and relaxation
1 heartbeat
what type of charge does the heart muscle have at rest?
muscle is polarized at rest
depolarization
contraction
where are sodium and calcium ions located? (cardiovascular)
the outer membrane of the cell
where are potassium ions located? (cardiovascular)
inside the cell
what happens to the ions during depolarization?
sodium and calcium ions move through channels in the cell membrane to the interior
potassium ions move through channels in the cell membrane to the exterior
repolarization
relaxation
what happens to the ions during repolarization?
ions are on the wrong sides of the cell membrane so they return to their original location
where is the cardiovascular conduction impulse generated and where does it go?
generated from the SA node at the base, to the apex, and back up to the base
passes through the muscle fibers of the atrial walls in a wavelike fashion
SA node —> AV node —> bundle of His —> Purkinje fibers
systole
myocardial contraction and depolarization
working phase of the cycle where muscle cells are depolarized
what happens during systole?
cardiac chamber empties itself of blood
diastole
myocardial relaxation and repolarization
what happens during diastole?
chambers fill with blood
where can normal heart sounds be best heard?
left side near the elbow
lub heart sound
tricuspid and mitral valves closing after atrial systole
dub heart sound
pulmonary and aortic valves close after ventricular systole
cardiac output
volume of blood ejected out of the left ventricle over a unit of time (usually 1 minute)
stroke volume
volume of blood ejected from the left ventricle during 1 contraction
represents the strength of the heart beat
preload
volume of blood the ventricle receives from the atrium
afterload
physical resistance presented by the artery the ventricle is ejecting blood into
pulse
rhythmic contraction and expansion of the arteries as blood is through them
dog/cat pulse point
femoral artery
cow pulse points
coccygeal artery and facial artery
horse pulse point
mandibular artery and posterior digital artery
mean arterial pressure
average pressure during 1 cardiac cycle
indicates tissue perfusion during anesthesia
oscillometric blood pressure
method using a cuff and arterial pulse is detected electronically
doppler blood pressure
method using a cuff, a small ultrasound probe, and a sphygmomanometer
