Lecture 2.2 ECG Diagnosis

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???? Lecture 2.2ECG Diagnosis

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• ??? ????,IEEE Fellow

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Sinus Rhythms
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Sinus Rhythms

• True heart rate is detected by taking a pulse.
• Many reasons why there are no corresponding pulse
  to go with an electrical beat.
• Normal PRI 0.12 0.20 s, normal QRS width less
  than 0.12 s.
• Sinus rhythm allows the atria to contract before
  the ventricles.
• If two contracts at the same time, blood would
  flow backwards jugular veins in the neck to
  pulse.
• Electrical impulse slows down in AV node,
  allowing atria to contract first.

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Normal Sinus Rhythm
Heart rate between 60 100 per minute. Sinus
rhythm rounded, upright P wave. Non-sinus
rhythm notched, pointed, inverted or absent P
wave.
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Sinus Bradycardia
Heart rate slower than 60 per minute. Disease
based on patient athletes have normal rate below
60.
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Sinus Tachycardia
Heart rate faster than 100 per minute Nervous or
excited. Serious cases early stages of shock to
compensate blood pressure fall.
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Sinus Arrythmia
The longest R-R interval differs from the
shortest by at least 0.16 s. Speeding up when
inhaling slowing down when exhaling common
in young.
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Atrial Rhythms

• Rhytms that originates in the atria.
• P waves weird shaped
• Pointy, sometime flat, notch in the middle
• Sometime diphasic one part above the isoelectric
  line, one part below it.

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Premature Atrial Complex
pointed!
Atrial pacemaker interrupts underlying rhythm,
resetting sinus node. Might find a single P wave
without QRS complex T waves - AV node still
refractory.
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Atrial Fibrillation (a-fib)
no discernible P waves
irregular QRS rate
Electricity in atria follows random repetitive
path, causing atria to quiver - common among
the elderly. Atria unable to pump blood,
ventricles depolarized at irregular intervals -
clots may form in left atrium predisposition for
a stroke.
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Atrial Flutter
saw tooth, conduction ratio (P QRS) 2 1
The atia are depolarizing at an extremely rapid
rate. The AV node only conduct impulses up to 220
per minute - not all impulses will be conducted.
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Junctional Rhythms
P wave upside down. P wave may occur before,
during, or after the QRS complex.
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Premature Junctional Complex
Not a rhythm but denotes that a junctional
pacemaker interrupts the underlying rhythm.
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Junctional Escape
A backup pacemaker in the AV junction has a
rate of 40 60. When the sinus rate falls to 30,
this junctional pacemaker calls the shots.
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Junctional Tachycardia
The rate is faster than 100.
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Accelerated Junctional Rhythm
The rate is too fast to be considered junctional
escape but too slow to be considered junctional
tachycardia.
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Supraventricular Tachycardia (SVT)

• Paroxysmal SVT a group containing tachycardia
  rhythms (of supraventricular origin) which all
  have a similar appearance.

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Paroxysmal Supraventricular Tachycardia (PSVT)
A supraventricular tachycardia (SVT)

• Normal sinus rhythm to a PSVT of 180 in only
  second.
• AV nodal reentrant tachycardia (AVNRT)
• AV reentrant tachycardia (with accessory pathway)
• Atrial tachycardia

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Ventricular Rhythm

• Impulses originate in ventricles wide QRS (gt
  0.100.12s).
• One of the bundle branches could be blocked.

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Premature Ventricle Complex
Originally premature ventricular contraction. P
wave before PVC to P wave after PVC is twice P-P
underlying interval. Normal skipping a beat
unhealthy bad omen.
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Ventricular Fibrillation (v-fib)
coarse
fine
Functional atria playing tennis or jogging
functional ventricle staying alive. Can progress
to death within minutes.
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Ventricular Tachycardia
Faster than 100 usually above 120 may exceed
250. No time for blood to refill may or may not
have a pulse. V-tach to V-fib to asystole.
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Ventricular Escape
Often called idioventricular escape backup
pacemaker in ventricles. Sinus junctional
pacemakers have failed. A block that prevents
impulses of sinus pacemaker from reaching
ventricles.
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Asystole
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Atrioventicular Heart Blocks

• 1st degree heart block AV conduction is slowed.
• 2nd degree heart block AV conduction is
  incompletely (i.e. occasionally) blocked.
• 3rd degree heart block AV conduction is
  completely blocked.

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1st Degree Heart Blocks
Sinus rhythm with a first degree heart block
PRI longer than 0.20s.
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2nd Degree Heart Block Type I
Also called Mobitz I or Wenckebach. PRI getting
longer with each electric beat until eventually P
occurs but QRS never shows (skipping a beat).
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2nd Degree Heart Block Type II
Also called Mobitz II worse than Wenckebach. QRS
suddenly fails to show up after a P usually
appears next. Lacks the increasing PRI as with
Wenckebach.
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3rd Degree Heart Blocks
No AV conduction ventricles backup pacemaker
calls the shots. Often P occuring at regular
intervals with QRS occuring at irregular
intervals. Sometimes P follows QRS, sometimes
vice versa dont affect each other.
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ECG Artifacts

• Electrical interference by outside sources,
  electrical noise from elsewhere in the body, poor
  contact, machine malfunction.

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Pacing Spikes
Implanted pacemaker is firing.
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Reversed Leads/ Misplaced Electrodes
All waves are upside-down.
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AC Interference
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Muscle/ Noise
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Wandering Baseline
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Absolute Heart Block
QRS shows no relationship with P occurs very
rarely.