copyright © 2006 by elsevier, inc. abnormal sinus rhythms tachycardia means a fast heart rate...
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Copyright © 2006 by Elsevier, Inc.
Abnormal Sinus Rhythms
• Tachycardia means a fast heart rate usually greater than 100 beats /min.
Figure 13-1; Guyton & Hall
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Abnormal Sinus Rhythms (cont’d)
• Bradycardia means a slow heart rate usually less than 60 beats /min
Figure 13-2: Guyton & Hall
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Sinoatrial Block
• In rare instances impulses from S-A node are blocked.
• New pacemaker is region of heart with the fastest discharge rate, usually the A-V node.
Note: no P waves and slow rateFigure 13-4; Guyton & Hall
SA Node
AV Node
Delay
Prolonged P-R Interval
Prolonged P-R Interval
First Degree Heart Block
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Intermittent Block
SA Node
AV Node
Second Degree Heart Block
ConductedBlockedConducted
Blocked
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Third Degree Complete Block
• Total block through the A-V node or A-V bundle
• P waves are completely dissociated from QRST complexes
• Ventricles escape and A-V nodal rhythm ensues
Figure 13-7; Guyton & Hall
HR = 37
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Premature Atrial Contractions (cont’d)
Figure 13-9; Guyton & Hall
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Premature Ventricular Contractions (PVC’s)
Figure 13-3; Guyton & Hall
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Atrial Paroxysmal Tachycardia
• Paroxysmal means a series of rapid heart beats suddenly start and then suddenly stop.
• Can be stopped with a vagal reflex or quinidine or procainimide
• P wave is inverted if origin is near A-V node• Occurs by re-entrant pathways
Figure 13-12; Guyton & Hall
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Ventricular Paroxysmal Tachycardia
• Usually does not occur unless there has been ischemic damage
• Quinidine increases refractory period of cardiac muscle and can eliminate the problem
Figure 13-13; Guyton & Hall
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Atrial Fibrillation
Figure 13-19; Guyton & Hall
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Atrial Flutter
Figure 13-20; Guyton & Hall
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Ventricular Fibrillation
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