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Arrythmias

Physiology of Normal Rhythm Generation

Potential Pacemakers of the Heart

Vagal Stimulus

Overview of Arrhythmias

Arrhythmia due to Normal or Abnormal Pulse Initiation – these are all very RARE

Arrhythmias due to Abnormal Pulse Conduction – most common mechanism of arrhythmias

Simultaneous Abnormalities of Impulse Generation and Conduction

Tachycardias: Characteristics and Mechanisms

Tachycardia

Mechanism

Location

Rate Range

AV or Va Conduction

Sinus Tachycardia

Automatic

Sinus Node

³ 100 bpm

1:1

Atrial Fibrillation

Random Reentry

Atria; usu. >300 bpm

260-450 bpm,

Variable

Atrial Flutter

Ordered Reentry

R.Atrium; 300± 20 bpm

240-350 bpm,

2:1 or variable

Atrial Variable

Tachycardia

i.Reentry
ii.Automatic
iii.Triggered

Atria
Atria
Atria

150-240 bpm
?
150-240 bpm

1:1, 2:1,or
?
1:1,2:1, or

Variable

DAD (caused by digitalis)

 

 

 

AV Nodal Tachycardia

Ordered Reentry

AV node usually

120-250 bpm

1:1

AV Reentry
(WPW or concealed)

Ordered Reentry

Circuit (accessory AV
connection, atria, AV

node, His, Purkinje
system, ventricles)

140-250 bpm,

1:1

Accelerated AV

junctional tachycardia

Automatic or ? Triggered

AV junction (AV node

and His bundle)

61-200 bpm,

usu. 80-130 bpm

1:1 or variable

Accelerated idio-

ventricular rhythm

Abnormal automaticity

Purkinje fibers

>60 - ? bpm

Variable, 1:1, or AV

dissociation

Ventricular tachycardia

Reentry

Automatic (rare)

Ventricles

Ventricles

120-300 bpm

AV dissoc., variable, or 1:1

AV dissoc., variable, or 1:1

Bundle Branch

Reentrant Tachycardia

Reentry

Bundle branches and

ventricular septum

160-250 bpm,

usu. 195-240 bpm

AV dissoc., variable, or 1:1

Right Ventricular outflow tract tachycardia

? Triggered (DAD)

Right Ventricular

outflow tract

120-220 bpm

AV dissoc., variable, or 1:1

Torsade de pointes

? Triggered (EAD)

Ventricles

>200 bpm

AV dissociation

Sinus Node Reentry

Reentry

Sinus node and R.atrium

?110-180 bpm

1:1 or variable

Arrythmias in Detail

Bradyarrhythmias

Tachyarrhythmias