ECG Part II Flashcards
what are the general concepts for ECG hypertrophy patterns?
takes longer to traverse enlarged cardiac structure: resulting deflection wider
more mass due to hypertrophy, then resulting deflection will be taller/larger
direction of deflection varies based on which chamber is enlarged
what is P pulmonale?
P wave is too tall
what can cause P pulmonale?
right atrial enlargement
respiratory disease
what is P mitrale?
P wave is longer/wider than 0.04 sec (dog or cat)
what causes P mitrale?
left atrial enlargement
why does left atrial enlargement cause a wider P wave?
takes longer for impulse to traverse the enlarged left atrium
what does biatrial enlargement look like on an ECG?
P wave >0.04 sec and >0.4 mV
what is the mean electrical axis useful for?
to determine the general direction of electrical forces
what is the mean electrical axis calculated from?
frontal plane leads
what are the three ways to calculate the mean electrical axis?
tallest R wave
plot algebraic sum of QRS in leads I and III
find isoelectric lead, select perpendicular lead, direction of main force is the mean electrical axis in frontal plane
with left ventricular enlargement, which leads have tall R waves?
II
III
aVF
V2
what might you see with left ventricular enlargement on an ECG?
tall R waves
prolonged QRS duration
left axis shift
tall R wave V3 or V6
what should you look for when looking for a right ventricular enlargement pattern?
deep S wave in lead II
S waves in I, II, III, aVF
deep S waves in V3 or V6
right axis shift
positive T wave V10
prolonged QRS duration
what does left bundle branch block look like on ECG?
looks like left ventricular enlargement pattern
QRS too wide: >0.08sec in dogs, >0.06sec in cats
what is left bundle branch block almost always associated with?
significant left heart disease
what is the J point?
inflection point on ECG where thee QRS complex ends and the ST segment starts
what does right bundle branch block look like?
right ventricular enlargement pattern
how can you distinguish between right ventricular enlargement and right bundle branch block on an ECG?
QRS too wide with right bundle branch block
what can right bundle branch block be confused with?
right ventricular hypertrophy
what is the significance of right bundle branch block?
can be normal
can be intermittent
can be associated with disease of right ventricle
what is the QRS duration like in left anterior fascicular block?
often fairly normal
what is abnormal in left anterior fascicular block on the ECG?
mean electrical axis shifted to the left
deep S waves in II, III, aVF
small Q and bigger R in lead I
what is left anterior fascicular block on an ECG associated with?
various forms of heart disease in cats
especially hypertrophic cardiomyopathy
what does biatrial enlargement look like?
P wave >0.04 sec and >0.4 mV
which leads are used to calculate the mean electrical axis?
frontal plane leads: I, II, III, aVL, aVR, aVF
what is the normal mean electrical axis for a dog?
between 40 and 105: leads II and aVF
what is the normal mean electrical axis for a cat?
between 0 and 160: leads I (0), II, aVF, and III
which leads are associated with a left axis shift in dogs?
I and aVL
which leads are associated with a right axis shift in dogs?
III and aVR
is the mean electrical axis shifted with left anterior fascicular block?
yes: left
