8. Electrocardiography Flashcards
(40 cards)
what defines normal sinus rhythm
a P wave for every QRS, rate 60-100, P waves with normal configuration: upright in II, negative or biphasic in V1.
if PR interval is < 5 mm, what is the cause?
1st degree AV block, usually due to slow conduction in the AV node
if QRS is < 3 mm, what is the cause?
consider a bundle branch block
what should the Q-T interval be like?
should be less than half the R to R length. if not, prolonged QT.
what would define LAD?
positive in I, negative in aVF
what would define RAD?
negative in I
normal axis looks like what, in what leads?
positive in I, positive in aVF
with hypertrophy, how will the axis vector change?
will point more towards the point of hypertrophy
with infarct, how will the axis vector change?
will point away from point of ischemia
best leads for analysis of P wave?
II and V1
what will we see in lead II if there is RAE?
in lead II, RAE increases the height of the P wave.
what will we see in lead II if there is LAE?
in lead II, LAE will increase the duration of the P wave
what will we see in lead V1 if there is RAE?
tall initial positive deflection
what will we see in lead V1 if there is LAE?
wide and deep negative deflection (1mm by 1mm)
a QRS interval of > 3 mm –> what?
His bundle delay, bundle branch block
in terms of the functioning of the heart, what does LBBB create?
delay in activation of the L side of the heart.
in terms of the functioning of the heart, what does RBBB create?
delay in activation of the R side of the heart
key points for LBBB
- wide QRS
- predominantly + complex in V6, neg in V1
key points for RBBB
- wide QRS
- RSR’ complex in V1 (rabbit ears)
- ST-T depression in leads with late QRS positivity
what does lead I look like with left anterior hemiblock?
predominantly positive QRS, left axis deviation
what does lead I look like with left posterior hemiblock?
predominantly negative QRS, right axis deviation
why does hypertrophy lead to higher voltage?
the mass of muscle being depol is increased
LVH increases QRS voltage in what leads?
I, aVL, V5, V6
RVH increases QRS voltage in what leads?
V1, V2, aVF, III
