Download ECG NOTES

Introduction to ECGs
Conduction System
Heart Beat
Graphic from Boston Scientific International.
Start the Heart
Now we’re going to look at
what you just did.
ECG
ECG Parts
• P – Atrial depolarization (contraction)
• QRS – Ventricular depolarization
(contraction – BP systole)
• T – Ventricular repolarization
(rest – BP diastole)
• U – Atrial repolarization
(rest – BP diastole)
R to R interval
• The time between the R waves on two
consecutive heartbeats.
Important “Times”
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1 small square = 0.04 second
1 large square = 0.2 second
Atrial contraction – P-R interval (PRI) = 0.1-0.2 second
Ventricular contraction – QRS complex = 0.04-0.11 second
Always use 6 second (30 large squares) strip to analyze an ECG
waveform
• This is what I want you to remember. These
squares represent a certain amount of time.
This helps us determine the patient’s heart rate
and regularity of heartbeat.
Now some math!
• If your heart beats 75 times per
minute, how long is the R to R
interval?
Answer: 0.8 seconds.
Types of heart rhythms
Sinus
Atrial
Ventricular
Sinus Rhythms – always have P
wave followed by QRS
• Normal Sinus Rhythm
(NSR) rate is
60-100 and rhythm is
regular
Types of sinus rhythms
Normal Sinus Rhythm (NSR)
Sinus arrhythmia
Sinus bradycardia
Sinus tachycardia
Sinus arrhythmia – rate is 60-100
and rhythm is irregular
Sinus bradycardia – rate is less
than 60 and is usually regular
Sinus tachycardia – rate is more
than 100 and less than 150 is
usually regular
Atrial Rhythms
P wave and/or PR interval are
abnormal.
QRS may be missing after
some P waves.
QRS is always normal, if it is
present
Premature Atrial Contraction (PAC)
• Rate is usually normal and may be regular except
when the PAC occurs. Some contractions have a
shortened PR interval or the P wave may not be
identified because it is buried in the T wave.
Atrial tachycardia (A Tach)
Rate is 150-250 and usually regular. PR interval is shorter than
normal and the P wave may move up on the T wave or be
buried in it (wet T). Each P wave is followed by a QRS complex.
Atrial Flutter (AF)
• Rate is 250-400. P waves are usually 0.2 seconds each and
occur in clusters of 2, 3, or 4 (look like saw teeth). Each cluster
is followed by a QRS complex at regular intervals. Because of
this, they are classified as being AF 2:1, 3:1, or 4:1.
Atrial fibrilliation (A-Fib)
• Atrial rate is too fast to count and individual P waves
may be difficult to identify. Normal QRS complexes
appear at irregular intervals. There will be many more
P waves than QRS complexes. May cause blood clots
to form and be sent to the brain, heart or lungs.
• Atrial Fibrillation
Ventricular Rhythms – rate varies.
No P wave in front of abnormally
wide QRS complexes (they will be
greater than 0.1 second). It may be
difficult to identify parts as being
QRST. There will be more QRS
complexes than P waves in the
strip.
Premature Ventricular Contraction
• Rate is usually normal and may be regular except
when PVC occurs. PVC may occur alone at regular
intervals (bigeminy, trigeminy) or in clusters (salvos). If
6 or more PVCs occur in 1 minute, the heart is
becoming very irritable and ventricular tachycardia can
begin at any time.
Ventricular tachycardia (V Tach)
• Rate is 150-250 and regular (looks like ric rac). No P
waves are seen. This is a continuous PVC run.
Ventricular fibrillation (V Fib)
• Rate is too irregular to count. Cannot identify
any par of the waveform.
Asystole – Straight line
• No heart activity is seen.
• Clinical death is present.
• Will become biological death if lasts longer than 4-6
minutes.
This is all for now
• The rest of these slides are about heart
disease and we will probably go over them
at another time
Pathology of MI
• Plaque builds up slowly (frequently LAD)
• Sudden blockage occurs and muscle and
nerve tissue distal begin to malfunction
and then die
• Abnormal activity and contractions
• Leads to V Fib/Asystole
• Scar tissue may form during healing and
cause disrhythmias.
Coronary Vessels
Plaque
Myocardial Infarction
• Heart Attack
MI Treatment
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Aimed at restoring coronary blood flow
Angioplasty and stent placement
Coronary artery by-pass graft (CABG)
Anticoagulants: heparin and coumadin
Aspirin (ASA): anticoagulant and antiinflammatory agent
Pathology of CHF
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Congestive heart failure
Damaged valves or ventricular muscle
Heart cannot completely empty
Right failure – blood backs up in legs (pitting
edema, 1+ to 4+)
• Left failure – blood backs up in lungs (pulmonary
edema)
• Cardiotonic – lanoxin, digoxin (not if pulse < 60)
• Diuretic - lasix
CHF
• Heart Failure
Test Your Knowledge
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Label the Parts of Your Heart
Label Your Heart's Electrical System
Name Your Blood Vessels
Define Common Heart Problems