17. Normal ECG Flashcards
x axis of ECG:
- 1 large box
- 1 small box
lg: 0.2 s
sm: 0.04s
y axis of ECG:
- 1 large box
- 1 small box
lg: 0.5 mV
sm: 0.1 mV
in what leads in the P wave upright?
inverted?
variable?
upright: 1, 2, V4-V6, AVF
inverted: AVR
variable: 3, AVL, chest leads
what is the normal duration for PR interval
0.12 - 0.2 s (3-5 sm boxes)
what is the normal duration of QRS complex
0.05 s - 0.10 s (1-2.5 sm boxes)
what is the upper limit duration for a Q wave
0.03 s (less than 1 sm box)
should be narrow and small
in what leads is ok normal for the Q wave to be 1-2 mm?
1, AVL, AVF, V5, V6
what is a normal ST elevation?
what does an abnormal elevation indicate?
not more than 1 mm (1 sm box) in standard leads, 2 mm (2 sm boxes) in chest leads
subepicardial or transmural injury/ischemia
what is a normal ST depression>?
what does an abnormal depression indicate?
1/2 mm (1/2 sm box)
subendocardial injury/ischemia
in what leads in the T wave upright?
inverted?
variable?
upright: 1, 2, V3-V6
inverted: AVR
variable: 3, AVL, AVF, V1, V2
what is the upper limit of height for T wave
standard: <5 mm (1 lg box)
chest: <10 mm (2 lg boxes)
what do abnormal T waves indicate
- ischemic patterns (associated with inverted or tall upright T waves)
- hyperkalemia
what do abnormal ST segments indicate
pattern of injury
what do abnormal Q waves or QRS complexes indicate
pattern of necrosis or infarction
what do broad notched p waves, taller in I than III, indicate
p- mitrale
left atrial enlargement; left atrium is dilated and potentially scarred, lending to the bifid nature of the P wave, and the characteristic “M” pattern
what do flat P waves in I with tall, pointed P waves in II and III indicate
p- pulmonale
right atrial enlargement, p wave > 2.5 mm
what do inverted P waves in II and III, with short PR interval indicate
AV junctional rhythm
a prolonged PR interval indicates what pathology
- AV block d/t coronary or rheumatic disease
- hypterthyroidism
a shortened PR interval indicates what pathology
- AV junctional or low atrial rhythms
- wolff parkinson white syndrome
- lown ganong levine syndrome
what are the best leads for reading p-waves
II and V1
how do you evaluate rhythm
- is the a P wave before every QRS and vice versa
- look at PR interval (prolonged –> AV block)
- look a QRS interval (prolonged –> BBB)
in what diagnoses would you see a P wave following a QRS complex
- SVT
- junctional rhythm
in what diagnoses would you not see P waves
- afib (350-500 bpm)
- atrial flutter
- junctional or ventricular escape rhythms
- junctional tachycardia
- VTACH
