1. View the slide show
2. Interpret the EKGs
3. Advance slides to review findings
4. Good luck!
1. Take a deep breath
2. Analyze rate
3. Analyze rhythm
4. Look at axis
5. Look for injury/strain/ischemic patterns
6. Look for conduction defecits (RBBB, LBBB)
7. Hypertrophy, meds, toxic effects
8. Make your measurments (PR, QT/QTc, QRS)
Sample EKG #1. Determine rate, rhythm, diagnosis, axis
Rate: approx 75/min
Rhythm: Baseline sinus rhythm, P:QRS is 1:1
Axis: Physiologic
Injury: ST elevation is present in the anterior, septal, and literal leads.
Massive ST segment elevation is present in V2-V6, with moderate ST
elevation that obscures visualization of the QRS complex in lead one.
Changes are consistent with LCA occlusion.
Other: R wave progression is difficult to determine secondary to the
pathological ST-T changes. No evidence of chamber enlargement or
hypertrophy.
The EKG reveals an atrial flutter at a rate of approx 100 per
minute. The QRS complexes are narrow and reveal a
physiological axis. There is evidence of a premature
ventricular complex, readily identifiable in the lateral chest
leads. No evidence of ischemia or infarction. No evidence
of R or L bundle branch block. Atrial flutter is conducted at
approx 3:1. (3 flutter waves to one QRS).
The EKG reveals an irregularly irregular rhythm suggestive of
atrial fibrillation. The rate is variable, with a controlled or slow
ventricular response. The axis is physiologic. ST-T changes
suggestive of ischemia/injury are present in leads II, III, and
aVF. ST elevation of >1mm in limb leads is indicative of a
possible inferior wall myocardial infarction. Reciprocal changes
are seen in leads one and aVL. Early R wave progression.
Interpretation of EKG #4:
This EKG reveals a baseline sinus rhythm. Rate cannot be
determined definitively. The QRS is wide; V1 reveals an
RSR’ pattern consistent with a right bundle branch block.
The axis is physiologic but is not easy to determine because
of ST elevation present in leads III and aVF (inferior wall).
Other abnormal T changes are seen (T wave inversion) in
leads V1-V4. ST segment depression is present in the lateral
chest leads as well. No evidence of chamber enlargement.
ST elevation in III and aVF with reciprocal depression in I
and aVL may be consistent with an inferior wall MI (RCA
lesion.)
Interpretation of EKG#5:
Baseline sinus rhythm.
Rate appears normal (60-100)
Axis is physiologic
No evidence of block or conduction abnormality
There is widespread ST segment elevation in all leads
GLOBAL ST elevation is consistent with pericarditis
EKG #6 Interpretation:
EKG #6 reveals a baseline sinus rhythm.
Rate approximately 80 bpm
Axis is physiologic
Complexes in V5 greater than 35 mm suggest LVH
ST segment depression in leads V4-V6 in the setting of
LVH is suggestive of a, “strain pattern”.
No evidence of bundle brnach block
ST segment depression in inferior chest leads
EKG #7 Interpretation:
Baseline sinus rhythm.
Rate of approx 80/min
Axis is physiologic
No evidence of ventricular hypertrophy, but RAH is possible
due to P wave in lead II >0.5 mm.
Possible RBBB because of RSR’ in V1 and QRS >0.10
Note pathologic Q waves in II, III, aVF
Pathologic Q waves are >0.04s or >1/3 the height of the R
wave.
Changes consistent with inferior wall myocardial infarction
(old, possibly transmural).
R wave progression preserved.
EKG #8
Interpretation of EKG #8:
Baseline sinus rhythm, rate approx 80.
Right axis deviation, as evidenced by a primarily negative
complex in lead I.
Possible RAH due to large lead II P wave
Possible RVH due to R>S in V1
Note pervasive strain pattern due to RVH evidenced in
precordial leads.
The presence of RAD plus the R>S in V1 is suggestive of
RVH.
EKG Interpretation #8:
Though the picture has poor resolution, it is clear that
the lateral leads reveal a pattern of digoxin toxicity. Even
though rate is impossible to determine, the “cored-out”
and depressed ST segments in the lateral precordial
leads suggest digoxin toxicity. Furthermore, the irregular
R to R intervals hint at a baseline rhythm of atrial
fibrillation. Many patients take digoxin for chronic atrial
fibrillation. Moderate left axis deviation.
EKG #9:
This rhythm strip reveals a profound bradycardia. There
is no relationship between the atria (P waves) and QRS
complexes. This is consistent with complete A-V
dissociation, or third degree heart block. This rhythm
frequently requires emergent pacing.
EKG #10 Interpretation:
This EKG reveals a baseline sinus rhythm (p’s are difficult to
discern.) The rhythm is a sinus tachycardia at approximately
100 per minute. Massive ST segment elevation is present in
leads II, III, and aVF. Reciprocal changes (depression) in
leads I and aVL. Note that the precordial chest leads (v4R to
V6R) are placed on the right side of the chest. ST segment in a
“right-sided” EKG likely indicates an inferior wall MI that
involves the RIGHT ventricle. Be careful when giving these
patients NTG. Administration of nitrates, due to the alteration
of venous preload, can precipitate hypotension. Treat these
MI’s with fluid first. The axis is physiologic, no evidence of
chamber enlargement. R wave progression is not of value in
this EKG because of the right sided chest leads.
Rhythm interpretation:
-The first strip reveals a prolonged PR interval, with 1:1
conduction. This rhythm is a first degree A/V block.
-The second strip is a 4:1 (or 3:1) atrial flutter.
-The third rhythm strip reveals the typical atrial
fibrillation. Note the fibrillatory baseline with irregular R
to R intervals.
The QT/QTc Interval: Calculation and Significance
Measurement:
Parameter:
Abnormalities:
QTc:
Lengthening:
From the beginning of the Q wave to the
end of the T wave
Normal QT intervals range from 0.360.41.
Hypercalcemia will shorten the QT interval
and yield measurements from 0.26-0.36s.
The QT interval varies with heart rate. The
corrected QT interval is calculated by
adjusting your measurement for the
patient’s heart rate. The QT divided by the
square root of the R to R interval typically
gives a QTc around 0.44 seconds.
Diseases, drugs, and toxins can prolong
the QT interval and precipitate attacks of
lethal ventricular arrhythmias.
Long QT syndrome, “Romano-Ward” Syndrome EKG:
The QTc, adjusted for rate, would almost certainly be greater
than 0.44 seconds. You can see in this example that the QTc is
approximately 0.5-0.6 seconds (almost 3 large boxes!)
Rate Cheat Sheet
Besides calculating the number of R waves in a 3 or 6 second
strip and multiplying by 20 or 10 seconds, simply divide the
number of small (0.04s) units between consecutive R waves
into 1500.
-The heart rate can also be calculated from the R to R interval.
Simply divide the number of large boxes (0.2s) between
consecutive R waves into 300.
-15 large boxes is a three second strip!
-30 large boxes represents a six second strip!
-For irregularly irregular rhythms, try to calculate rate with a
decent time interval, preferably greater than a 3 second strip.
Potassium summary:
Digitalis effect summary:
In addition to a wide variety of atrial conduction defects,
ventricular ectopy, and heart blocks, early digitalis toxicity
manifests itself as: a shortening of the QT interval in
addition to scooped-out appearing ST segments.
Precise axis calculation, anyone?
Remember that it is simply a method of addition. I+III=II. The mean
QRS vector will also point 90 degrees away from the most isoelectric lead.
Leads with large amplitude R waves will shift the mean QRS vector in their
general direction. Remember about dropping those stubborn
perpendiculars?
Chamber enlargement
review:
Name that
hypertrophy?
a) RVH
b) LVH
c) RAH
d) LAH
The EKG findings are consistent with: RVH
Criteria for right ventricular hypertrophy include:
-Tall R wave in lead V1 (R>S)
-qR pattern in V1
-Right axis deviation
-T wave inversion in right to mid precordial leads possible
-Commonly due to ASD!
-The pattern of T wave inversion is called, “strain”and is
consistent with repolarization problems in hypertrophied
muscle.
Biphasic P waves, P waves with a terminal negative
component or notched P waves are consistent with……..?
Left Atrial Hypertrophy!
What about the following EKG tracing?
Right atrial enlargement:
Factors suggesting right atrial enlargement include:
-Tall, humped P waves
-May be higher than 2.5 mm
-Patient history may be significant for asthma, COPD, or
pulmonary hypertension
A zebra says, “Good-bye”
What syndrome is typical of the following EKG features?
-Short PR interval
-Bouts of tachycardia
-Upsloping R wave, “delta”wave
-Often abberant conduction through ventricles (wide>0.10s QRS)
-The name of this zebra is….
-Next slide for answer and EKG.
Lead two reveals the short PR, delta wave, and the widerappearing QRS typical of Wolff-Parkinson-White
syndrome.