Normal findings of a Pwave?
- Duration: 0.10 sec
- Amplitude: 0.5 and 2.5 mm
- Upright: I, II, avF, V4, V5, V6
- Inverted: aVR
- Variable: III, avL, V1, V2, V3
Abnormal findings of a Pwave?
- M shaped or notched P Wave
- M-Mitral: Left atrial enlargement
- Peaked P Wave (over .11 sec)
- Right atrial enlargement atrial dilatation
- P Waves absent
- Sinoatrial node block
- AV Nodal rhythm
Normal PR Interval?
- Duration: 0.12 to 0.20 sec
- Prolonged PR interval (> .20)
- AV Node Block
- Shortened PR interval (< .12, accelerated)
- Wolf-Parkinson-White Syndrome (WPW
- PR segment: normally isoelectric (not
Normal Q wave?
- Duration: 0.04 sec (1 small boxes)
- Amplitude: < 25% of amplitude of R wave in that lead
- Always the first negative deflection below baseline
- Variable: III, aVR
- may not always have one
normal RS Wave?
Negative waveform (below baseline) following R
Depolarization of right and left ventricle
normal QRS complex?
- Duration: Limb leads (I, II, III): ≤ 0.10
- Prolonged QRS complex (> 0.12)
- High QRS amplitude
- Evaluate for Left Ventricular Hypertrophy (LVH)
- Upright I, aVL, V5, V6 and II, III, and aVF
normal J point?
- Point at the end of the QRS complex and the beginning of the ST segment
- should be aligned with beginning of Q wave to be normal
normal ST segment?
- a little down or up slope is fine
- ST segment is isoelectric
- Early part of repolarization of the ventricles
- PR segment is used as baseline for identification of deviation from baseline
- Measure 2 small box (0.08 sec) from J
- Elevation or Depression with 2 small box
- above or below in multiple leads
Normal T wave?
Smooth and asymetrical
- Amplitude : <5 mm
- Upright: I, II, V3, V4, V5, V6
- Tall T Waves: Myocardial infarction, Myocardial ischemia, Cerebrovascular accident
goes hand in hand with the QRS complex
normal QT interval?
- Normal QT decreases with increasing heart rate
- Calculation of QTc or corrected QT (Bazett's Formula)
- QTc = QT/(sqrt RR Interval)
- QTc is normally <0.44
a long interval could be for an athlete or someone with hypertension
What is the large box method?
- its is a close estimate
- count the number of large boxes (5mm) between beats
- divide by 300 (=1 minute)
small box method?
- count number of small boxes (1mm) between beats
- divide by 1500 ( =1minute)