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14 Cards in this Set
- Front
- Back
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if heart is on right side of chest, where do you place leads?
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reverse arm leads
place precordial leads on the right (leave V1 and V2) |
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Precedes every QRS
Amplitude: 0.5-2.5 mm Duration: 0.06 (in babies) to 0.12 seconds Configuration: small, rounded peak, all are similar in size and shape. Direction: Usually positive (upright) in leads I, II, III and aVF and negative in aVR. |
P wave
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The upward limb and downward limbs of P wave are equal.
Summit or apex of P wave is slightly rounded. Right atrium depolarizes first then the left atrium. But it is not obvious in normal atria. |
P wave shape
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Inverted P-wave
Junctional rhythm. 2. Wide P-wave (P- mitrale) Left atrial enlargement 3. Peaked P-wave (P-pulmonale)RAE 4. Saw-tooth appearance Atrial flutter 5. Absent normal P wave Atrial fibrillation |
P wave abnormalities
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includes the p wave and the PR segment.
Duration 0.12-0.2 seconds Short interval: ectopic origin close to AV node Long interval: delay through AV node or bundle of His. |
PR interval
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Location: Normally follows the PR interval
Amplitude: varies Duration: 0.06-0.10 seconds. Configuration: (Q wave may or may not be there), followed by upward R and downward S. Nomenclature: If multiple R waves, the second positive wave is called R’. The second negative wave is S’ Indicates: Ventricular depolarization occurred normally |
normal QRS complex
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Wide QRS: QRS duration > 0.12 seconds.
Bundle branch block Conduction through abnormal pathway ectopic origin Drugs may also prolong the QRS duration due to slowing of conduction. |
abnormal QRS complex
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Normally seen in leads 2,3, aVF , V5 and V6 due to the ventricular septal depolarization from left to right.
The duration is usually less than 0.03 seconds and the amplitude is variable. Abnormally wide waves> 0.04 sec. may be indicative of myocardial death. (Infarction) Abnormally high amplitude waves may be due to septal hypertrophy as in hypertrophic cardiomyopathy. |
Q waves
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R waves are inscribed when electrical activity is coming towards the lead; positive wave.
S waves are inscribed when electrical activity is going away from the lead. Negative wave. R wave amplitude depends on the ventricular muscle mass and any interference due to too much fat or large breast in case of females. Normal young athletes with large muscle mass have high amplitude R waves. The position of the diaphragm also interferes with the amplitude of R wave in the inferior leads 2,3, and aVF |
R and S waves
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Usually isoelectric
If elevated: sign of myocardial injury or infarction If depressed: myocardial ischemia suspected. |
ST segment
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Represents ventricular recovery or Repolarization
Location: follows the ST segment Amplitude: 0.5mm to 25% of R wave. Duration: 0.10 to 0.25 seconds Configuration: round, slightly asymmetrical (ascends slower than descends) Deflection: usually positive in all leads except aVR and V1 |
T wave
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Inverted T waves in leads normally expected to have upright T wave is abnormal.
Very tall T waves > 25% of the R wave with narrow base are abnormal. Very flat T waves with wide base are also abnormal. Upright T waves in Leads aVR and V1 are also abnormal. |
abnormal T wave morphology
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Extends from the beginning of QRS to the end of the T wave.
Needs to be corrected for the heart rate. Long interval: slow Ventricular Repolarization; predecessor to serious rhythms! May be congenital or due to drugs. Short interval: usually from medication or hypercalcemia or congenital |
QT interval
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Purkinje fiber repolarization
Not uncommon on ECG in the young. Configuration: Upright and rounded If prominent: may be due to high calcium, low potassium or due to drugs. T and U may be merging making long QT interval |
U wave
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