copyright © 2006 by elsevier, inc. abnormal sinus rhythms tachycardia means a fast heart rate...

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


Abnormal Sinus Rhythms (cont’d)

• Bradycardia means a slow heart rate usually less than 60 beats /min

Figure 13-2: Guyton & Hall


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


Intermittent Block

SA Node

AV Node

Second Degree Heart Block

ConductedBlockedConducted

Blocked



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


HR = 37


Premature Atrial Contractions (cont’d)



Premature Ventricular Contractions (PVC’s)



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



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



Atrial Fibrillation



Atrial Flutter



Ventricular Fibrillation

copyright © 2006 by elsevier, inc. abnormal sinus rhythms tachycardia means a fast heart rate...

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