Make your own free website on Tripod.com
 

                      Basic Criteria for Diagnosis in ECG

Normal Sinus Rhythm
Sinus Bradycardia
Sinus Tachycardia
Atrial Fibrillation
Atrial Flutter
Right Atrial Enlargement
Left Atrial Enlargement
Right Ventricular Hypertrophy
Left Ventricular Hypertrophy
Premature Ventricular Contraction
Accelerated Idioventricular Rhythm
First Degree AV Block
Third Degree AV Block
Right Bundle Branch Block
Left Bundle Branch Block
Left Anterior Hemiblock
Left Posterior Hemiblock
Bifascicular Blocks
Changes in Myocardial Ischemia
What is an Abnormal Q Wave?
Evolution of Changes in Q Wave MI
Anterior Q Wave Myocardial Infarction
Anteroseptal Q Wave Myocardial Infarction
Anterolateral Q Wave Myocardial Infarction
Inferior Q Wave Myocardial Infarction
Inferolateral Q Wave Myocardial Infarction
Posterior Q Wave Myocardial Infarction
Lateral Q Wave Myocardial Infarction
Right Ventricular Q Wave Myocardial Infarction

Normal Sinus Rhythm (Chou/Knilans P. 321)

[1] A P wave precedes each QRS complex.
[2] Rate is between 60 and 100 bpm for adults (50 - 90 bpm is probably more realistic).
[3] P wave axis of +15 to +75 degrees. A P axis less than 0, or greater than +90 indicates an ectopic atrial pacemaker.
[4] P wave is usually upright in leads I, II, and aVF, and inverted in aVR. It is also usually upright in V3 - V6.
[5] P-P variation is less than 0.16 second (otherwise it is sinus arrhythmia).
 
 

Sinus Bradycardia (Chou/Knilans P. 323)

[1] Sinus rate of less than 60 bpm in an adult (50 bpm is more realistic).
[2] P wave has a normal axis, PR interval is usually greater than 0.12 second.
[3] If sinus rate is less than 40 bpm, consider 2:1 AV block.
[4] Not considered clinically significant unless less than 50 bpm.
 
 

Sinus Tachycardia (Chou/Knilans P. 324)

[1] Sinus rate greater than 100 bpm in an adult.
[2] Frequently occurs due to alcohol, caffeine, epinephrine, atropine, fever, hypotension, hypoxia, CHF, anemia, hyperthyroidism, AV fistula, pheochromocytoma, myocarditis, and in 1/3 of MI patients.
 
 

Atrial Fibrillation (Chou/Knilans P. 354)

[1] P waves are absent, and replaced by fibrillatory (f) waves, producing random oscillation in the baseline.
[2] Ventricular rhythm is usually irregularly irregular.
 
 

Atrial Flutter (Chou/Knilans P. 354)

[1] Atrial deflections with a sawtooth appearance (F waves).
[2] Atrial rate usually 250 - 350 bpm.
[3] Ventricular complexes may vary in rate and regularity due to nonconduction of some F waves through the AV node.
[4] QRS complex may be normal or abnormal, due to pre-existing disease, or conduction abnormalities.

Right Atrial Enlargement (Chou/Knilans P. 28)

[1] Tall and peaked P wave with a height of 2.5 mm or more in leads II, III, and aVF, with a normal duration (this is called "P pulmonale").
[2] P wave axis of +75 degrees or greater.
[3] Positive deflection of the P in lead V1 or V2 is greater than 1.5 mm.
(no examples)
 

Left Atrial Enlargement (Chou/Knilans P. 23)

[1] The product of (time x voltage) in the P terminal force in V1 is equal to, or more negative than -0.04 mm-second (1 small box wide, and 1 small box deep).
[2] P wave is notched and equal to, or wider than 0.12 second (this is called "P mitrale").
[3] P wave axis less than +15 degrees (frequently not used in practice, and on this website).
 
 

Right Ventricular Hypertrophy (Chou/Knilans P. 54)

QRS duration of less than 0.12 second, and one or more of the following:
[1] QRS axis of +110 degrees or greater.
[2] R/S ratio in V1 or V3R greater than 1.
[3] R wave in V1 greater than, or equal to, 7 mm.
[4] S wave in V1 less than 2 mm.
[5] qR pattern in V1.
[6] rSR' in V1 with R' greater than 10 mm.
[7] R wave in V1 plus S wave in V5 or V6 greater than 10.5 mm.
[8] R/S ratio in V5 or V6 less than, or equal to, 1.
[9] Onset of intrinsicoid deflection (downslope of R wave after the peak) in V1 is 0.035 to 0.055 second.
(no examples)
 

Left Ventricular Hypertrophy (Chou/Knilans P. 37)

QRS duration less than 0.12 second, and one or more of the following:
[1] R wave in lead I plus S wave in lead III greater than 25 mm.
[2] S wave in aVR greater than 14 mm.
[3] R wave in aVL greater than 11 mm.
[4] R wave in aVF greater than 20 mm.
[5] R wave in V5 or V6 greater than 26 mm.
[6] R wave in V5 or V6 plus S wave in V1 greater than 35 mm.
[7] Largest R wave plus largest S wave in precordial leads greater than 45 mm.
 

Or using the Romhilt-Estes point score (LVH present if 5 or more total points, likely if 4 total points):
[1] 3 points
if largest R or S wave in the limb leads greater than, or equal to, 20 mm;
or S wave in V1 or V2 greater than, or equal to, 30 mm;
or R wave in V5 or V6 greater than, or equal to, 30 mm.
[2] ST-T segment changes ("LV strain" = ST-T vector shifted opposite to QRS vector)
3 points - if without digitalis,
1 point - if with digitalis.
[3] 3 points - left atrial involvement - terminal deflection of P wave in V1 is 1 box wide, and 1 box deep or more.
[4] 2 points - left axis deviation - QRS axis is -30 degrees or more negative.
[5] 1 point - QRS duration greater than, or equal to, 0.09 second.
[6] 1 point - intrinsicoid deflection in V5 and V6 greater than, or equal, to 0.05 second.
 
 

Premature Ventricular Contraction (Chou/Knilans P. 396)

[1] QRS complex occurs earlier than expected.
[2] QRS is abnormal in shape and width, with ST segment and T wave changes.
[3] There is usually a full "compensatory" pause after the PVC.
[4] There may or may not be conduction in retrograde fashion to the atria.
 
 

Accelerated Idioventricular Rhythm

[1] Rhythm is regular with a rate of 60 - 100 bpm.
[2] QRS complexes are abnormal in shape and duration.
[3] QRS is usually dissociated from the P waves.
[4] Ventricular capture and fusion beats can occur.
 
 

First Degree AV Block (Chou/Knilans P. 449)

[1] PR interval is greater than 0.20 second.
[2] Each P wave is followed by a QRS complex.
 
 

Third Degree AV Block (Chou/Knilans P. 455)

[1] Atrial and ventricular rhythms are independent.
[2] Atrial rate is faster than ventricular rate (if not, it is "AV dissociation").
[3] Ventricular rhythm is either junctional or idioventricular.
 
 

Right Bundle Branch Block (Chou/Knilans P. 88)

[1] QRS duration greater than 0.12 second.
[2] rsR' or rSR' pattern in right precordial leads.
[3] Delay in the onset of the intrinsicoid deflection (downslope following peak of the R wave) in the right precordial leads greater than 0.05 second.
[4] Wide S wave in leads I, V5, and V6.
 
 

Left Bundle Branch Block (Chou/Knilans P. 75)

[1] QRS duration greater than 0.12 second.
[2] Broad monophasic (notched or slurred) R wave in leads I, V5, and V6.
[3] Delay in the onset of the intrinsicoid deflection (downslope following peak of the R wave) in the V5 and V6 leads greater than 0.05 second.
[4] Displacement of the ST segment and T wave in a direction opposite to the main deflection of the QRS complex.
 
 

Left Anterior Hemiblock (Chou/Knilans P. 101)

[1] QRS axis between -30 and -90 degrees.
[2] qR or R complex in leads I and aVL; an rS complex in leads II, III, and aVF.
[3] Normal or slightly long QRS duration.
 
 

Left Posterior Hemiblock (Chou/Knilans P. 106)

[1] QRS axis of +90 to +180 degrees.
[2] S in lead I, a Q in lead III (S1Q3 pattern).
[3] Normal or slightly prolonged QRS duration.
 
 

Bifascicular Blocks (Chou/Knilans P. 111)

Right bundle branch block, with either left anterior hemiblock, or left posterior hemiblock.
 

RBBB with LAHB (most common, Chou/Knilans P. 112)
[1] QRS duration of 0.12 second or longer.
[2] RSR' pattern in lead V1, with R' broad and slurred.
[3] Wide and slurred S waves in leads I, V5, and V6.
[4] First half or 0.06 second of QRS has an axis between -30 and -90 degrees.
[5] Initial r wave in the inferior leads.
 

RBBB with LPHB (Chou/Knilans P. 115)
[1] QRS duration of 0.12 second or longer.
[2] RSR' pattern in lead V1, with R' broad and slurred.
[3] Wide and slurred S waves in leads I, V5, and V6.
[4] First half or 0.06 second of QRS has an axis +90 degrees, or greater, with an rS pattern in lead I, and qR pattern in leads II, III, and aVF.
[5] Initial r wave in the inferior leads.
 
 

Changes in Myocardial Ischemia (Chou/Knilans P. 189)

[1] Abnormally tall T waves (also occur in early MI).
[2] Symmetrically or deeply inverted T waves (also occur late in MI).
[3] ST segment depression.
[4] Nonspecific ST and T wave changes.
[5] Normalization of previously abnormal T waves.
[6] Prolongation of the QT interval.
 

What is an Abnormal Q Wave (Chou/Knilans P. 122)?

[1] A Q wave with a duration of greater than 0.04 second, or an amplitude greater than 25% of the following R wave.
[2] These guidelines do not apply to leads III, aVR, and V1, where wide and deep Q waves are found in normal patients.
[3] In lead aVL, a Q wave is abnormal if it has a duration greater than 0.04 second, or an amplitude greater than 50% of the following R wave.
[4] A Q wave is abnormal (even if of a short duration), when seen in leads V2, V3, and V4, which usually display an initial R wave.
 

Evolution of Changes in Q Wave MI (Chou/Knilans P. 124)

[1] Tall T waves.
[2] ST segment elevation (used as evidence that a MI is "acute").
[3] Abnormal Q waves.
[4] Decrease of ST elevation, with T wave inversion.
[5] Isoelectric ST segment with T wave inversion.
 

Anterior Q Wave Myocardial Infarction (Chou/Knilans P. 122)

rS pattern in V1, abnormal Q in one or more leads V2, V3, or V4.
 

Anteroseptal Q Wave Myocardial Infarction (Chou/Knilans P. 122)

QS (meaning a big Q, where you can't tell if it is really a Q or a S) pattern in leads V1, V2, V3, or V4.
 

Anterolateral Q Wave Myocardial Infarction (Chou/Knilans P. 122)

Abnormal Q in leads V4, V5, V6, I, or aVL.
 
 

Inferior Q Wave Myocardial Infarction (Chou/Knilans P. 122)

Q in leads II, or III; with an abnormal Q in aVF.
 

Inferolateral Q Wave Myocardial Infarction (Chou/Knilans P. 122)

Q in II, III, and aVF (inferior MI) plus abnormal Q in leads V5 or V6.
 

Posterior Q Wave Myocardial Infarction (Chou/Knilans P. 122)

Initial R waves in leads V1, and V2 with a duration of 0.04 second or more, with an R/S ratio of greater than 1 (in a patient 30 years or older, without right ventricular hypertrophy).
 
 

Lateral Q Wave Myocardial Infarction (Chou/Knilans P. 122)

Abnormal Q waves in leads I and aVL.
 

Right Ventricular Q Wave Myocardial Infarction (Chou/Knilans P. 136)

[1] Signs of inferior or inferoposterior MI.
[2] ST segment elevation of 1 mm or more in one or more of the right precordial leads.
[3] If you suspect a right ventricular MI, do a right-sided ECG (leads I, II, III, aVR, aVL, avF in the usual positions; but leads V1 - V6 placed on the right side as the mirror image of their usual left-sided positions). Then look at lead V4R for ST elevation (88% sensitive, 78% specific for RV MI).
(no examples)

 If you would like to read more about ECG's, consider the following books:

[1] "Rapid Interpretation of EKG's", by Dale Dubin, Cover Publishing Company, copyright 1996. Easy reading, a very good first look at ECG's.
[2] "Basic Dysrhythmias", by Robert J. Huszar, Mosby-Year Book, Inc., copyright 1994. Intermediate reading, with beautiful illustrations of various phenomena.
[3] "Electrocardiology in Clinical Practice", by Te-Chuan Chou and Timothy K. Knilans, W.B. Saunders Company, copyright 1996. Advanced and detailed, with complete references evaluating the usefulness of various criteria.