L5: Intraventricular Conduction Defects Flashcards
Hallmark of s Bundle branch block
Wide QRS > .12 s
Incomplete BBB
RR’ configuration with narrow QRS
RBBB is seen in (2)
Coronary artery disease
Pulmonary Embolism
What else does a Right BBB have besides a wide QRS?
V1→ M-shaped RR’
Lead I, V6→ Wide S wave
ST-T waves in RBBB oriented opposite to the direction of the terminal QRS forces
RBBB with abnormal ST changes means….
T wave oriented in same direction as terminal QRS forces in limb leads
What’s the axis in a RBBB?
Normal, 0-90
What else does a Left BBB have besides a wide QRS?
Leads I+V6→ Wide R wave
V1, V2→ reciprocal, broad, deep S waves (leads over RV)
How can you differentiate hypertrophy from a BBB?
QRS < .12s
“incomplete BBB pattern”
a change in the
QRS axis, but the QRS duration is not
prolonged
HEMIBLOCK
LAHB axis
(-) 45 to (-) 90 = LAD
LPHB axis
(+) 120 to (+) 180 = RAD
Other causes of RAD that must be excluded in cases of LPHB
cor pulmonale (RAE) pulmonary htn
Besides LAD, LAHB shows
Lead III→ Deep S waves
Lead I→ Tall R waves
Normal QRS
Beside RAD, LPHB shows
Lead III→ Tall R waves
Lead I→ Deep S waves
Normal QRS
LAHB vs LPHB: axis
LAHB: strong LAD
LPHB: strong RAD
LAHB vs LPHB: Lead III
LAHB: deep S waves
LPHB: tall R waves
LAHB vs LPHB: Lead I
LAHB: tall R waves
LPHB: deep S waves
LAHB vs LPHB: QRS duration
Both normal
RBBB + LAHB axis
Same as LAHB!
(-) 45 to (-) 90 = LAD
RBBB + LPHB axis
Same as LPHB!
(+) 120 to (+) 180 = RAD
Bifascicular block
Features of RBBB plus frontal plane features of the fascicular block (axis deviation)
Which hemiblock is more commonly seen?
LPHB
Including in combination with RBBB
When the QRS is prolonged without features of either RBBB or LBBB
Nonspecific IVCD
Causes of nonspecific IVCD
Ventricular hypertrophy (especially LVH)
Myocardial infarction (peri-infarction blocks)
Certain antiarrhythmic drugs→ quinidine, flecainide
Hyperkalemia
Paced complexes
Bundle of kent=
Wolf parkinson white syndrome
James fibers=
Lown Ganong Levine Syndrome
Delta wave=
Wolf parkinson white syndrome
Pre-excitation syndromes are marked by
Short PR interval
Wolf parkinson white syndrome is vulnerable to
PSVT
Which has a wide QRS, WPW or LGL?
Wolf parkinson white syndrome
Which has delta waves, WPW or LGL?
Wolf parkinson white syndrome
You see a short PR interval (
Lown Ganong Levine Syndrome
