Lecture 9: Normal ECG Flashcards
How much time is represented between each dark line on an ECG?
0.2 seconds
How much time is represented between each light line on an ECG?
0.04 seconds
In what leads is the P wave inverted or variable?
- Inverted in AVR
- Variable in III and AVL
What is the normal time range for P-R interval?
.12-.20 seconds
A P-R interval >.20 seconds signifies what?
A 1st degree AV block
What is normal duration range of the QRS complex?
.05-.10 seconds
What should be observed in the ST segment?
Normally it is isoelectric; sometimes normally elevated, never normally depressed
In what leads is the T wave observed upright?
I, II, V3-V6
In what leads is the T wave observed inverted?
AVR
What is the normal height of a T wave in standard and precordial leads?
Standard = not greater than 5mm Precordial = not greater than 10mm
QT duration can be used as an indicator of what pathologies?
Myocardial Ischemia Myocardial Injury Myocardial Infarction
What kind of pattern is associated with inverted T waves?
Ischemic pattern
Abnormal Q wave or QS complex is associated with a pattern of?
Necrosis or infarction
In what leads can the direction of the T wave be variable?
III, aVL, aVF, and V1-V2
Which individuals can have a prominence of the ST segment as a variation of their normal?
African American’s
What 2 syndromes do you see a shortened P-R interval?
1) Wolff-Parkinson-White Syndrom 2) Lown-Ganong-Levine Syndrome
A QRS <0.12 seconds tells us there is no?
Bundle branch block
What bpm constitutes Tachycardia and Bradycardia?
Tachy = >100 bpm Brady = <60 bpm
What numbers constitute the rule of 3’s for determining heart rate from an ECG
Count from R wave –> R wave 300, 150, 100, 75, 60, 50
How to count slow or irregular rhythms?
Use the 3-second strip at the top of the strip. Count the number of QRS complexes that appear in 6-seconds.Add a zero or multiply by 10 to the number of QRS complexes you counted.
To get any heart rate from the ECG what do you divide?
Heart rate per minute = 300/Number of large squares 300 –> 300/2 –> 300/3 –> 300/4…etc.
If counting number of QRS between a 3-second marker what do you multiply by?
20
What are the rates between 300 and 150 (smaller sqaures)?
300 –> 250 –> 214 –> 188 –> 167 –> 150
Using only the small boxes how do you find the rate?
1500/number of small boxes = heart rate per minute
What leads are perpendicular to lead I, II, and III?
Lead I –> aVF Lead II –> aVL Lead III –> aVR
If lead I is positive and aVF is positive what is the axis?
Normal axis (0 to +90 degrees)
If lead I is positive and aVF is negative what is the axis?
Left axis deviation (-30 to -90 degrees)
If lead I is negative and aVF is positive what is the axis?
Right axis deviation (+100 to +180)
If both lead I and aVF are negative what is the axis?
Extreme right axis deviation (-90 to +180)
In what leads is the P-wave upright?
I, II, V4-V6, and aVF
Normal T wave height in both standard and precordial leads?
Standard: Not greater than 5mm Precordial: Not greater than 10mm
What abnormality is shown here?
P-mitrale: notched and broad P-waves (look like ‘M’)
What abnormality is shown here?
P-pulmonale: Tall Pointed and Peaked P-waves
Seen in pt’s with Pulmonary disease
What abnormality is seen here?
A-V junctional rhythm: inverted P in leads II and III with short P-R interval
A shortened P-R interval <0.12 secs signifies?
A-V junctional and low atrial rhythms
A wide QRS complex signifies?
A bundle branch block
