ecg interpretation criteria review. axis deviation ✦ rad = if r wave in iii > r wave in ii ✦...
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ECG Interpretation
Criteria Review
ECG Interpretation
Criteria Review
Axis Deviation
✦ RAD = If R wave in III > R wave in II
✦ LAD = If R wave in aVL > I; and deep S wave in III
Left
Right
Axis Deviation Criteria
LEAD I LEAD II (or Lead aVF or III)
Normal Positive Positive
LAD Positive Negative
RAD Negative Positive
Intermediate axis Negative Negative
Axis Deviation
✦ LAD = possible left anterior fasicular block
✦ RAD = possible left posterior fasicular block
Right Atrial Abnormality Criteria
✦ Tall P waves in lead II
✦ (or III, aVF and sometimes V1)
Left Atrial Abnormality
• Lead II (and I) show wide P waves
• (second hump due to delayed depolarization of the left atrium)
• (P mitrale: mitral valve disease)
• V1 may show a bi-phasic P wave
• 1 box wide, 1 box deep• (biphasic since right atria is
anterior to the left atria)
Right Ventricular Hypertrophy
Criteria
1. In V1, R wave is greater than the S wave - or - R in V1 greater than 7 mm
2.Right axis deviation
3. In V1, T wave inversion (reason unknown)
Left Ventricular Hypertrophy Criteria
✦ If S wave in V1 or V2 + R wave in V5 or V6 ≥ 35 mm...
✦ ...or, R wave > 11 (or 13) mm in aVL or I...
✦ ...or, R in I + S in III > 25 mm.
✦ Also
✦ LVH is more likely with a “strain pattern” or ST segment changes
✦ Left axis deviation
✦ Left atrial abnormality
Right Bundle Branch Block Criteria
✦ V1 or V2 = rSR’ - “M” or rabbit ear shape
✦ V5 or V6 = qRS
✦ Large R waves
✦ Right chest leads: T wave inversion (“secondary changes” since they reflect a delay in depolarization not an actual change in depolarization).
✦ Complete RBBB: QRS > 0.12 sec.
✦ Incomplete RBBB: QRS = 0.10 to 0.12 sec.
Left Bundle Branch Block Criteria
✦ Wide QRS complex
✦ V1 = QS (or rS) and may have a “W” shape to it.
✦ V6 = R or notched R and may show a “M” shape or rabbit ears
✦ Secondary T wave inversion
✦ Secondary if in lead with tall R waves
✦ Primary if in right precordial leads
Incomplete Bundle Branch Blocks
✦ RBBB or LBBB where QRS is between .10 and .12 with same QRS features
Left Anterior Fascicular Block
✦ Limb leads
✦ QRS less width less than 0.12 sec.
✦ QRS axis = Left axis deviation (-45° or more)
✦ if S wave in aVF is greater than R wave in lead I
✦ small Q wave in lead I, aVL, or V6
Left Posterior Fascicular Block
✦ Right axis deviation (QRS axis +120° or more)
✦ S wave in lead I and a Q wave in lead III (S1Q3)
✦ Rare
Bifascicular Block
✦ Two of the three fascicles are blocked.
✦ Most common is RBBB with left anterior fascicular block.
SubendocardialIschemia
Partial occlusion
TransmuralInfarction (MI)
Complete occlusion
✦ A. Normal ECG prior to MI
✦ B. Hyperacute T wave changes - increased T wave amplitude and width; may also see ST elevation
✦ C. Marked ST elevation with hyperacute T wave changes (transmural injury)
✦ D. Pathologic Q waves, less ST elevation, terminal T wave inversion (necrosis)
✦ E. Pathologic Q waves, T wave inversion (necrosis and fibrosis)
✦ F. Pathologic Q waves, upright T waves (fibrosis)
Infarction
Anterior Infarctions
✦ Abnormal Q waves in chest leads
✦ Anterior MI can show loss of R wave progression in the chest leads
Inferior Infarctions
✦ Abnormal Q waves in leads II, III, and aVF
Lateral
✦ Lateral - V5 and V6
✦ High lateral when ST elevation and Q waves localized to leads I and aVL
Posterior MI✦ Tall R waves in V1,V2
✦ R/S ratio > 1 in V1, V2
✦ The tall, anterior R waves are mirror images of a pathological, posterior Q waves.
✦ Absences of right axis deviation (found with RVH)
✦ ST segment depression in V1-V3
✦ Often seen with inferior MI
Infarctions or BBB✦ RBBB & LBBB
✦ T wave inversion and ST segment depression in V1 & V2 (RBBB) and V5 & V6 (LBBB)
✦ MI
✦ T wave inversion and ST segment depression in additional leads
✦ Likely loss of R wave progression
Infarctions and BBB✦ RBBB and MI
✦ usual ECG changes in leads other than V1 and V2
✦ septal MI - upright T waves in V1 and V2
✦ with just RBBB the T waves should be inverted so upright T waves w/ RBBB are “abnormal” and indicated septal MI
Infarctions and LBBB
✦ Infarctions often damage the left bundle branch leading to a new or recent LBBB
✦ expect to see upright T waves in left chest leads
✦ septal MI are very difficult to assess with LBBB
Subendocardial Ischemia
✦ ST Segment depression
✦ Anterior leads (I, aVl and V1-V6)
✦ Inferior leads (II, III, and aVf)
✦ may see ST segment elevation in aVr
✦ T wave inversion
✦ Poor R wave progression
Subendocardial Infarction
✦ No Q waves (non-Q wave infarction)
✦ Persistent ST segment depression
✦ T wave inversion
Sinus Bradycardia
✦ HR less than 60 bpm
Sinus Tachycardia
✦ HR > 100 bpm
Premature Atrial Complexes (PAC)
1. Normal conduction
2. Conducted with aberration
✦ a fascicles or bundle branch is refractory
✦ wide QRS
3. Non-conducted
✦ the AV node was still refractory; P wave will be close to the T wave
✦ no QRS complex
Atrial Tachycardia
AV Nodal Reentrant Tachycardia
✦ Rapid recirculating impluse in the AV node area (140-250 beats/min)
✦ No P waves (hidden in QRS complex) or may be just before or after the QRS complex
✦ Negative P waves in lead II
Figure 14-6Figure 14-6
Atrial Flutter
✦ Sawtooth; F waves (easiest seen in II, III, & aVF)
✦ Atrial rate of about 300 bpm
✦ Ventricular rate150, 100 or 75 beats/min
✦ 2:1, 3:1 and 4:1
Atrial Fibrillation
✦ No organized depolarization in atria.
✦ Irregular “f waves” can range from looking almost like P waves to a flat line.
✦ Atrial rate is about 600 bpm
✦ Normal QRS w/ ventricular rate ~110-180 but random & irregular
Junctional Rhythm
Accelerated Junctional Rhythm
WPW
First Degree AV Block
2nd Degree AV Block, Type 1
2nd Degree AV Block, Type 2
2rd Degree AV Block
Premature Ventricular Contractions
✦Characteristics
1.Premature and occur before the next normal beat
2.Wide (> 0.12 ms) and the T wave is usually opposite of the QRS
3.Bizarre looking
✦ PVCs usually precede a P wave.
✦ A nonsinus P wave may follow the PVC
PVC✦ Unifocal (monomorphic) PVCs
✦ same appearance in the same lead ✦ small focus✦ normal and diseased hearts
PVC✦ Polymorphic (multifocal and multiform) PVCs
✦ different appearance in the same lead ✦ multiform = different coupling intervals✦ multifocal = same coupling intervals✦ usually diseased hearts
Multiform
Idioventricular Rhythm
Couplet
Triplet
Bigeminy and Trigeminy
Ventricular Tachycardia
...more than three PVCs
Torsades de Pointes
Ventricular Fibrillation
Note the course and fine waves