Normal EKG Readings - Dr. Johnston Flashcards
When do you see the U wave
Hyperkalemia
How much in time and length is each line on the ECG (each light line)
1mm = 0.04sec (HORIZONTALLY) 1mm = 0.1mV (VERTICALLY)
How much time and length is each dark line on the ECG
5mm = 0.2sec (HORIZONTALLY) 5mm = 0.5mV (VERTICALLY)
How long should the PR interval be
*not over 0.20sec
NORMAL : 0.12sec - 0.20sec
PR interval is what
From beginning of P to beginning of Q
PR segment is what
From end of P to beginning of Q
QRS interval is how long in normal ECG
Less than 0.12sec
What happens in T wave
Ventricular repolarization when K+ leaves the myocytes
QT interval is what
From beginning of Q to end of T
*VENTRICULAR SYSTOLE
How long is a normal QT interval
LESS then HALF of previous RR interval
P wave should look how
- Upright above baseline in*
- LIMB LEADS 1 and 2
- CHEST LEADS V4 and V6
- AVF - inverted in*
- AVR - Variable in
- 3
- AVL
What happens if AVR in P wave is not inverted
Junctional beat
What happens during the PR interval in the heart
The SA node fires and sends signal to Ventricular muscle fibers (0.12sec-0.20sec)
*not greater then 0.20sec
QRS complex should be how long
0.05sec- 0.10sec
Q wave should be how long
No more then 0.03sec
When would you see small narrow 1mm-2mm height Q waves
Which leads
LEADS 1
AVL, AVF
LEADS V5 + V6
ST segment is what kind of line
Isoelectric line (same level as PR segment)
ST segment can be elevated or depressed as a normal sign in what leads
NORMAL ELEVATION : 1. only up to 1mm (standard leads) 2. Only up to 2mm (chest leads) NORMA DEPRESSION : * only is less then 0.5mm in any lead
ST depression is due to
Subendocardial injury
ST elevation is due to
Subepicardial injury
Transmural injury
Ischemia
T wave shape
Round and asymmetrical UPRIGHT IN: - LIMB LEAD 1 and 2 - CHEST LEAD V3-V6 INVERTED IN: -AVR VARIABLE IN: - AVL, AVF, V1, V2
T wave should be how high
Up to 5mm only (STANDARD LEADS)
Up to 10mm only (PRECORDIAL LEADS)
What can this show : inverted T waves or tall upright T waves,
HYPERKALEMIA
Ischemic patterns
What can this show : elevated ST segment
Pattern of injury
What can this show : not normal Q wave or QRS complex
Necrosis or infarction
LIMB leads include
1, 2, 3
Augmented limb leads include
AVR (right arm)
AVL (left arm)
AVF (foot)
PRECORDIAL leads include
V1-V6 (CHEST LEADS)
V1, V2 —> activity in AVR
V3,V4 —> anterior wall and ventricular septum activity
V5,V6 —> lateral wall of ventricle
What leads get activity from lateral heart
1, AVL, V5, V6
What leads get activity from inferior or diaphragmatic heart
2, 3, AVF
What leads get activity from anterior heart
V1-V4
How do you know the ECG is normal
The lead 1 is upright = positive impulse
The AVF is upright
*sinus rhythm
What happens with a notched broad looking P wave
Mitral stenosis (P-mitrale)
Patient can come in with atrial fibrosis
*most prominent in lead 1)
What happens with a tall pointed and peaked looking P wave
Lung problems (P-Pulmonale) COPD, emphysema, RESP failure , pulmonary HTN *flat P in lead 1, tall pointed in lead 2,3
What happens with a inverted looking P wave
Leads 2,3 has short PR interval (AV-Junctional Rhythm)
4 things that can shorten the PR interval
- AV- Junctional and atrial rhythm is low
- Wolf-Parkinson- white syndrome
- Lawn - Gangong- Levine syndrome
- Glycogen storage disease
2 things causing prolonged PR interval
- AV block : due to coronary disease, rheumatic disease
2. Some hyperthyroidism
Double R wave
Right bundle block
Deep Q wave
Old heart attack
When can you have ST depression normally
After exercise
Deep Inverted T wave
Anterior infarction
Tall upright T wave
Inferior infarction
Extreme tall T wave that i height or QRS
Myocardial ischemia no infarction
Sinus rhythm
P wave comes before QRS
PR interval should not be higher then
0.2sec
= no AV block
QRS should not be higher then
0.12sec
= no bundle branch block
Best leads to look at P wave
LEAD 2 and V1
U wave is what
Bundle or His and Purkinje fibers repolarize
Hypokalemia
How to treat tachycardia or bradycardia
Depends on the cause
How to calculate HR
2 ways
300/dark lines
OR
Number of beats in 3sec X 20
(Number of beats in 6sec X 10)
How to calculate HR if you want to use number of small boxes
1500/ number of small boxes
P : QRS ratio
= 1
What does it mean if the P wave comes after the QRS
SVT (AV nodal re-entry tachycardia)
Junctional rhythm
What happens if there is no P wave
Atrial fibrillation
Atrial flutter
Junctional or ventricular escape rhythm
Junctional tachycardia
How are the leads intersecting
What are perpendicular to each other
LEAD 1 perpendicular to AVF
LEAD 2 perpendicular to AVL
LEAD 3 perpendicular to AVR
What is the normal degree
What is the 90-180 degree
What is the negative degree
0-90 is normal (positive)
90-180= Right ward axis (positive)
0-90 (negative) = leftward axis
90-180 (negative) = extreme RIGTH axis deviation
What makes a normal EKG 0-90 positive degrees
The Lead 1 (x axis) and the AVF (y-axis) are both positive
How does the locations of each lead look on the circle diagram
Here
POSITIVE AXIS
+ lead 1
+ AVF
LEFT AXIS
+ lead 1
- AVF
RIGHT AXIS
- lead 1
+ AVF
EXTREME RIGHT AXIS
- lead 1
- AVF
(-90 to 180 positive)
Lead 1 +
AVF -
Lead 2 +
0-30 to (negative) left axis deviation
Lead 1 +
AVF -
Lead 2 -
30-90 (negative) left axis deviation
Lead 1 -
AVF +
Right axis deviation greater then 100 degrees (positive)
How to treat low HR
Atropine
How to find the isoelectric lead
The QRS that has half above base line and half below the base line (half negative and half positive)
If the isoelectric lead is lead 3 and lead 1 and AVF are + what is the degree
Perpendicular to lead 3 is AVR which is negative pole is at +30 degrees
What is the rate rhythm and axis here
75 HR sinus
Isoelectric is AVL,
Lead 2 is perpendicular to it and so = +60 degrees
What is the rate rhythm and axis here
75HR sinus
Lead 3 is isoelectric, AVR = +30 degrees
HOWEVER you use the smallest QRS if there is one*
= AVL = lead 2 = +60 degrees **
What is the rate rhythm and axis here
75HR - 100HR sinus LEAD 1 - AVF + = right axis deviation Most isoelectric is AVR, perpendicular is lead 3 = +100 degrees at its positive pole
What is the rate rhythm and axis here
50HR sinus
LEAD 1 +
AVF -
= left axis deviation
Isoelectric is lead 2, however AVR is the smallest
Lead 3 is perpendicular which is negative pole at = - 60 degrees
What is the rate rhythm and axis here
100HR sinus LEAD 1 + AVF - = left axis lead Isoelectric is AVR, perpendicular to it is a negative lead 3 = -60 degrees
