Diagnostics EKG Quiz 1 Flashcards
Resting heart electrical charge
-70
What is the (+) electrode
The “looker”
3 types of cardiac cells
Pacemaker cells: electrical power (sinus node)
Electrical conduction cells: wiring of heart
Myocardial cells: Machinery of heart
How long does it take to get from SA node to AV node
.04 sec
How long is pause at AV node
.1 sec
How long does it take for current to cross ventricles
.06 sec
Electrical current route of heart
SA Atrium AV Bundle of His Splits left and right
Left bundle Branch
Purkinje fibers
Right bundle branch
splits again into posterior/anterior fascicle
Sinus node rate
60-100
AV node rate
40-60
Bundle of his rate
40-60
Ventricles / purkinje fibers rate
30-45
Interval times
PR interval
0.12 - 0.20
Avg. = 0.18
Interval times
QRS duration
0.06 to 0.12
Avg. = 0.08
Interval times
QT interval
0.40 to 0.43 (less than half of R-R interval)
Avg. = 0.40
Interval times
ST interval
Avg. = 0.32
Segment times
ST Segment
0.08
Avg. HR
60-100
P wave time
- 04-0.12
2. 5mm
What is PR interval
Conduction pause of AV node
What does P wave represent
Atrial depolarization
What does QRS represent
Ventricular depolarization
What does T wave represent
Ventricular repolarization
Where is the Atrial repolarization on ECG
hidden in QRS
Difference between intervals and segments
Intervals include Wave
Segments do not
What does the flat line on the ecg represent
no electrical activity
Lead I direction
Left to right
Lead II direction
inferior to right
Lead III Direction
Inferior to left
AVF Direction
Inferior to heart
AVL Direction
Left to Heart
AVR Direction
Right to heart
What orientation are precordial leads
anterior
What are the inferior leads
II (+60)
III (+120)
AVF (+90)
What are the Lateral leads
I (+0)
AVL (-30)
V5
V6
What are the right sided leads
AVR (-150)
V1
What are the anterior leads
V3
V4
What are the septal leads
V3
V4
What is a normal axis
0 - 90 degrees (positive)
If there is a deviation, where is the problem
on the deviation side.
What are deviation leads
I
AVF
Causes of left axis deviation
Cause must be on left
ie. Left ventricular hypertrophy
Systemic hypertension
Aortic stenosis
Causes of right axis deviation
Cause must be on right
ie. Right ventricular hypertrophy
Pulmonary artery hypertension
Uncorrected congenital heart disease
RVH ECG findings
Right axis deviation
R wave larger than S wave in V1
S wave larger than R wave in V6
LVH ECG findings
R wave in V5 or V6
plus the S wave in V1 or V2
Exceeds 35mm
R wave in V5 exceeds 26mm
R wave in V6 exceeds 20mm
R wave in V6 exceeds R wave in V5
LVH ecg in limb leads
Any of these
R wave in lead AVL exceeds 11mm
R wave in lead AVF exceeds 20mm
R wave in lead I exceeds 13mm
R wave in lead I plus S wave in lead II exceeds 25mm
Amplitude on ECG strip
2 large squares = 1 mV
One small square = 0.1 mV
One large square = 0.5 mV
Time on ECG Strip
5 large squares = 1 sec
one small square = 0.04 sec
One large square = 0.2 sec
Ways to assess rate on ecg
6 second strip, count complexes, mult by 10
Large squares = 300,150,100,75,60,50,43,38
count small boxes between complexes, divide by 1500
ECG Analysis
Rate
Rhythm Are p waves present Are qrs narrow or wide (< or > 0.12) Is there a P for every QRS is the rhythm regular or irregular
Axis
Hypertrophy
intervals
infarction
Rhythm (Reg/irr)
regular
irregular
regular irregular
irregular irregular
Ectopic
originates elsewhere
R-R Interval
0.6 - 1.0
5 types of arrhythmias
Sinus Ectopic reentrant conduction blocks preexcitation syndromes
Sinus arrhythmias
Sinus Brady
Sinus Tach
Sinus arrhythmia
Sinus arrest, asystole, escape beat
Ectopic rhythms
Sinus node 60 - 100
Atrial pacemakers 60-75
AV node / junction / bundle of His 40-60
if 60-100 its accelerated junction
If > 100 its junctional tachycardia
Ventricles (bundle Branch, purkinje fiber) 30-45
Vent escape beats 30-45
Accelerated idioventricular rhythm 45-100
Ventricular tachycardia >100
Junctional rhythms and p waves
no p wave in junctional rhythm
A Fib
No p waves
atria is fibrillating
A flutter
saw tooth
lots of P waves
Carotid massage
Fool carotid baroreceptors into thinking blood pressure is rising
Vagal input decreases sinus node rate, slows conduction through AV node
can terminate AVNRT
can increase block rate of flutter to see waves more clearly
not diagnostic
can terminate AT
Vagal maneuvers
Valsalva, squatting can raise blood pressure and stimulate vagal input to heart
Decreases SA node rate
Slows conduction through AV node
