12 lead 2 Flashcards
Causes of widened QRS
- bundle branch block
2. ectopic ventricular beat
right bundle branch block displays
- widened QRS
- tall, upright (positive) in right sided leaded
- negative in left sided leads
- late forces to the right ventricle
- Positive in V1 and V2
- negative in I and V6
left bundle branch block displats
- widened QRS away from V1 and toward V6
- high voltage generated in the LV
- forces are away from the right sided leads (v1)
- forces are toward the left sided leads (V6)
hemiblocks cause
axis shifts without widening the QRS
in a normal axis, which leads are upright
Leads 1 and 2 are upright
in a left axis deviation with left anterior hemiblock,
Lead 1 is positive
Lead 2 is markedly negative
right axis deviation with left posterior hemiblock,
Lead I is markedly negative and Lead 2 is positive
____ cause axis shifts
distal block in the left bundle
___ cause left axis deviation
anterior fascicle
____ cause right axis deviation
posterior fascicle blocks
Left ventricular hypertrophy causes
- large positive deflections (R waves in V5 & V6 (lt. sided leads)
- large negative deflections (S waves) in V1 (rt. sided lead).
- normal QRS duration with very high voltage
Ischemia to due sudden high Oxygen demand in the presence of fixed coronary obstruction causes
depression of the ST segment
Ischemia due to acute coronary artery obstruction during low oxygen demand causes
T wave inversion
exercise test in a pt with fixed stenosis of coronary artery will result in
- normal resting ST segment
2. with exertion, ST depression due to transient ischemia
Axis shift?
- Right axis -
RVH or posterior hemiblock - Left axis -
LVH or anterior hemiblock
ST elevation?
injury if localized or pericarditis if diffuse
ST depression?
ischemia or subendocardial infarct
T inversion?
ischemia or secondary to hypertrophy or bundle block
Long QT?
consider electrolyte imbalance, drug effect
Why is the QRS widened in Right bundle branch block?
- tall, wide terminal R waves in V1 and V2
- Wide S waves in I and V6
- terminal forces are the the right
acute pericarditis
- diffuse ST elevations in multiple leads
2. no localization
Acute anterior MI
- ST elevations
2. Q waves in anterior leads (V1-V4)
acute inferior MI
- ST elevations
- Q waves in inferior leads (II, III, aVF)
- reciprocal ST depression in anterior leads (V2, V3)
