Bundle Branch Blocks and Chamber Enlargement All EKGs in this presentation have been borrowed from: The Alan E. Lindsay ECG Learning Center ;

Outline 1. Left Bundle Branch Block 2. Right Bundle Branch Block 3. Left Atrial Enlargement 4. Right Atrial Enlargement 5. Left Ventricular Enlargement 6. Right Ventricular Enlargement 7. Examples

Left Bundle Branch Block Criteria QRS duration ≥ 120ms Broad R wave in I and V 6 Prominent QS wave in V 1 Absence of q waves (including physiologic q waves) in I and V 6

Left Bundle Branch Block

Right Bundle Branch Block Criteria QRS duration ≥ 110ms rSR’ pattern or notched R wave in V 1 Wide S wave in I and V 6

Right Bundle Branch Block

Conduction Blocks and Secondary Repolarization Abnormalities LBBBRBBB

Left Atrial Enlargement Criteria P wave duration in II ≥120ms or Negative component of biphasic P wave in V 1 ≥ 1 “small box” in area

Right Atrial Enlargement Criteria P wave height in II ≥ 2.4mm or Positive component of biphasic P wave in V 1 ≥ 1 “small box” in area

Left Ventricular Hypertrophy Many sets of criteria for diagnosing LVH have been proposed: SensitivitySpecificity The sum of the S wave in V 1 and the R wave in either V 5 or V 6 > 35 mm 43%95% Sum of the largest precordial R wave and the largest precordial S wave > 45 mm 45%93% Romhilt-Estes Point System50-54%95-97%

Romhilt-Estes Point System for LVH CriterionPoints Amplitude (any of the following: Largest R or S wave in any limb lead ≥ 20mm S in V 1 or V 2 ≥ 30mm R in V 5 or V 6 ≥ 30mm 3 ST depressions or T wave inversions in lateral precordial leads, I, and/or aVL 3 Left atrial enlargement3 Left axis deviation2 QRS duration ≥ 90 ms1 Intrinsicoid deflection in V 5 or V 6 ≥ 50 ms1 4 points  Probable LVH5 points  Definite LVH

Left Ventricular Hypertrophy

Right Ventricular Hypertrophy Right axis deviation Right atrial enlargement Downsloping ST depressions in V 1 -V 3 (a.k.a. RV strain pattern) Tall R wave in V 1 Although there is no widely accepted criteria for detecting the presence of RVH, any combination of the following EKG features is suggestive of its presence:

Right Ventricular Hypertrophy

Examples

Left Ventricular Hypertrophy

Right Bundle Branch Block

Right Atrial Enlargement

Left Bundle Branch Block

Left Atrial Enlargement

Right Ventricular Hypertrophy

Left Ventricular Hypertrophy (with frequent PVCs)