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Supraventricular tachycardias
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Atrial flutter
• When the atrial rate is greater than 250bpm and
there is no flat baseline between the P waves.
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• P Waves: Flutter waves have a saw-toothed appearance
Atrial flutter
• AV node conducts impulses to the ventricles at a
2:1, 3:1, 4:1, or greater ratio (rarely 1:1).
• Degree of AV block may be consistent or variable.
5. ♥ Clinical Tip
oThe presence of A-flutter may be the first indication of
cardiac disease.
oSigns and symptoms depend on ventricular response
rate.
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Atrial Fibrillation (A-fib)
o Rapid, erratic electrical discharge comes from
multiple atrial ectopic foci.
o No organized atrial contractions are detectable.
o When the atrial muscle fibers contract independently
there are no P waves on the ECG, only an irregular
line
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8. ♥ Clinical Tip
oA-fib is usually a chronic arrhythmia associated with
underlying heart disease.
oSigns and symptoms depend on ventricular response
rate.
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9. PrematureAtrial Contraction (PAC)
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oA single complex occurs earlier than the next
expected sinus complex.
oAfter the PAC, sinus rhythm usually resumes.
10. ♥ Clinical Tip
In patients with heart disease, frequent PACs may
precede paroxysmal SV tachycardia (PSVT), A-fib,
or A-flutter.
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11. Paroxysmal SupraventricularTachycardia
(PSVT)
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• PSVT is a rapid rhythm that starts and stops suddenly.
• For accurate interpretation, the beginning or end of the
PSVT must be seen.
• PSVT is sometimes called paroxysmal atrial tachycardia
(PAT).
12. ♥ Clinical Tip
The patient may feel palpitations, dizziness, light-
headedness, or anxiety.
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13. Wolff-Parkinson-White (WPW) Syndrome
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• The only normal electrical connection between
the atria and ventricles is the His bindle.
• In WPW an accessory conduction pathway is
present between the atria and the ventricles.
14. • Electrical impulses are rapidly conducted to the
ventricles.
• These rapid impulses create a slurring of the
initial portion of the QRS called the delta wave.
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• Rate: Depends on rate of underlying rhythm
• Rhythm: Regular unless associated with A-fib
• P Waves: Normal (upright and uniform) unless A-fib is present
• PR Interval: Short (0.12 sec) if P wave is present
• QRS: Wide (0.10 sec); delta wave present
16. ♥ Clinical Tip
WPW is associated with narrow-complex tachycardias,
including A-flutter and A-fib.
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17. Junctional Tachycardia
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♥ Clinical Tip
• Signs and symptoms of decreased CO may be seen in
response to the rapid rate.
18. Junctional Escape Beat
An escape complex comes later than the next expected
sinus complex.
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19. Premature Junctional Contraction (PJC)
Enhanced automaticity in the AV junction produces
PJCs.
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20. ♥ Clinical Tip
Before deciding that isolated PJCs may be insignificant,
consider the cause.
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• Finally remember:
oThe ECG is easy to understand.
23. The normal ECG
Limits of normal duration:
oPR interval=200ms
oQRS complex duration=120ms
oQT interval=450ms
Rhythm:
oSinus arrhythmia
oSupraventricular extrasystoles are always normal
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24. The cardiac axis:
oNormal axis=QRS complex predominantly upward
in leads I,II and III; still normal if QRS complex is
downward in lead III.
oMinor degrees of right and left axis deviation are
within the normal range.
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25. QRS complex:
oSmall Q waves normal in leads I, VL and V6
(septal Q waves)
oRSR1 pattern in lead V1 normal if the duration
<120 ms (partial RBBB)
oR wave smaller than S wave in lead V1
oR wave in lead V6<25mm
oR wave in lead V6 plus S wave in lead V1<35mm
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26. ST segment:
oShould be isoelectric
T wave:
• May be inverted in:
oLead III
oLead VR
oLead V1
oLead V2
oLead V3, in black people
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27. What to look for:
1. The rhythm
2. P wave abnormalities:
- Peaked, tall: RAH
- Notched, broad: LAH
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28. 3. The cardiac axis:
• Rt axis deviation: Lead I downward
• Lt axis deviation: leads II and III or lead VF
downward
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29. What to look for:
4. The QRS complex:
• If wide, ventricular origin or BBB
• Tall R waves in V1= RVH
• Tall R waves in V6= LVH
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30. • Transposition point:
- R and S waves are equal in the chest leads
over the inter-ventricular septum (normally V3 or
V4)
- Clockwise rotation indicates chronic lung
disease
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31. • Q waves:
Small (septal) Q waves are normal in leads I, VL
and V6
Q wave in lead III but not VF is a normal variant
If present in more than one lead, longer than
40ms in duration and deeper than 2mm
indicates infarction
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What to look for:
32. Q waves in lead III but not in VF, plus Rt axis
deviation may indicate pulmonary embolism
Leads showing Q waves indicate site of
infarction
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33. What to look for:
5. The ST segment:
oRaised= acute MI and pericarditis
oDepressed= ischemia and with digoxin
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34. 6. T waves:
• Peaked= hyperkalemia
• Flat and prolonged= hypokalemia
• Inverted: -normal in some leads -ischemia -
infarction -Lt or Rt VH -may be inverted in V1-3
in PE -BBB
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35. What to look for:
7. U waves:
oCan be normal
oHypokalemia
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36. Troubleshooting ECG Problems
■ Place leads in the correct position.
■ Incorrect placement can give false readings.
■ Avoid placing leads over bony areas.
■ In patients with large breasts, place the electrodes under
the breast.
■ Accurate tracings are obtained through the least amount
of fat tissue.
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37. ■ Apply tincture of benzoin to the electrode sites if the
patient is diaphoretic.
■ The electrodes will adhere to the skin better.
■ Shave hair at the electrode site if it interferes with
contact between the electrode and skin.
■ Discard old electrodes and use new ones if the gel
on the back of the electrode dries.
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38. Cable Connections
• It is important to know if you are using an
American or European cable for ECG monitoring.
• The colors of the wires differ as shown below.
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40. REFERENCES:
1. The ECG made easy; John R. Hampton
2. The ECG in practice; John R. Hampton
3. 150 ECG problems; John R. Hampton
4. Others
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