Exam 1 - ECG Interpretation Flashcards
what can an ECG NOT tell you?
information on the mechanical activity of the heart - strength of contraction
what can an ECG tell you?
- info on chamber enlargement
- info regarding electrolyte concentrations
- info regarding myocardial hypoxia
- info about pericardial effusion
- info on conduction disturbances
- info on heart rate & rhythm
if a BIC pen is 150mm in length, and the paper speed is 25mm/sec, how many seconds does 1 pen length represent?
6 seconds
if a BIC pen is 150mm in length, and the paper speed is 50mm/sec, how many seconds does 1 pen length represent?
3 seconds
how big are small & little boxes on ECG strips?
little boxes: 1x1mm
big boxes: 5x5mm
what is the x-axis & y-axis on an ECG?
x-axis: time in mm/sec
y-axis: amplitude in mm/mv
what is a normal heart rate for adult cats?
160-240 bpm
what is a normal heart rate for adult dogs?
70-160 bpm
what is a normal heart rate for toy breeds?
less than or equal to 180 bpm
what is a normal heart rate for puppies?
less than or equal to 220 bpm
what is a commonly seen arrhythmia in dogs? what about cats?
dogs - sinus arrhythmia
cats - sinus tachycardia
at 25 mm/sec, how much time does 1 small box represent?
0.04 seconds
at 50 mm/sec, how much time does 1 small box represent?
0.02 seconds
what is a normal P wave interval in seconds for both dogs & cats?
less than or equal to 0.04 seconds
what is a normal QRS interval for dogs <20kg? dogs over 20 kg? giant breeds?
< 20 kg: less than or equal to 0.05s
> 20 kg: less than or equal to 0.06s
giant breeds: less than or equal to 0.065s
what is a normal QRS interval in cats?
less than or equal to 0.04s
at 10mm/mv (standard), how many mv does 1 small box represent?
0.1mv
what is a normal p wave amplitude in dogs & cats?
dogs: less than or equal to 0.4mv
cats: less than or equal to 0.2mv
what is a normal r wave amplitude in cats?
less than or equal to 0.9mv
what is a normal r wave amplitude for dogs <20kg? dogs over 20kg?
< 20 kg: less than or equal to 2.5mv
> 20 kg: less than or equal to 3.0mv
what p wave duration meets the criteria for left atrial enlargement in both dogs & cats?
greater than 0.04 seconds
what p wave amplitude meets the criteria for right atrial enlargement in dogs & cats?
dogs: greater than 0.4mv
cats: greater than 0.2mv
what r wave amplitude in lead II meets the criteria for left ventricular enlargement in dogs & cats?
dogs <20kg: greater than 2.5mv
dogs >20kg: greater than 3.0mv
cats: > 0.9mv
what are 4 criteria that support enlargement of the right ventricle seen on ecg?
- s wave in lead I, II, & III
- MEA to RV** only criteria for cats
- s wave in lead III > lead II > lead I
- s wave > r wave in lead II or s wave is > 0.7mv
how is an instantaneous heart rate calculated from an ECG?
of boxes from r wave to r wave - multiply by the time (either 0.04 seconds or 0.02 seconds)
60 seconds/^^ = instantaneous heart rate
what is the paper speed for horse ecgs?
12.5mm/sec, sensitivity 10mm/mv
0.08 sec/mm
what is this & what is it associated with? how can you minimize or resolve it?
artifact - electrical interference, will not have an associated repolarization (if it mimics a QRS, won’t have a t wave)
unplugging, use a grounded outlet, keep patient on an insulated surface, & ensure good electrode contact on skin
how can multiple leads help differentiate artifact from pathology on ecg?
artifact often won’t occur in 2 of 3 leads
what must you rule out if suspecting artifact on an ecg?
ectopic p waves & QRS complexes
what are ectopic complexes? what are their possible origins?
heart beats that don’t arise from the SA node
supraventricular or ventricular
how can you tell the difference between SVPB & VPCs using morphology?
VPCs - usually wide & bizarre QRS, if in lead II & negative, LV origin, if in lead II & positive, RV origin, p waves not associated because they may be buried or superimposed on other parts
SVPB - normal/narrow QRS & mostly positive complex in lead II, P WAVES ARE ABSENT
what is this?
ventricular premature complex - wide & bizarre QRS
what is this?
PSVB - QRS is similar to sinus QRS morphology
what are the hallmarks of afib seen on an ecg of a dog?
- irregular
- irregular
- irregular
- usually narrow
- usually fast
- no identifiable p waves
what are the most likely etiologies of atrial fibrillation in dogs?
- idiopathic or lone - not associated with structural heart disease
- DCM
- MMVD
- HCM
- hyperkalemia
- hemangiosarcoma
what is a fib?
no coordinated atrial contraction
what arrhythmia is seen here?
atrial fibrillation
