CH 6: Rhythms II Flashcards Preview

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Flashcards in CH 6: Rhythms II Deck (16):

Sinus block

-missed cycle w/ NO P-wave
-p-waves before and after missed cycle are identical


Who does SSS occur most often in

elderly individuals w/ heart disease


SSS is characterized by

marked sinus bradycardia w/o the normal escape mechanisms of atrial and junctional foci


Bradycardia-Tachycardia Syndrome

intermittent episodes of SVT mingled with the sinus bradycardia or SSS


1st degree AV block

-prolonged PR interval more than one large square (0.2 sec)
-PR prolongation is consistent in every cycle


2nd Degree AV block-Wenchebach

-progressive blocking of the AV node condition until the final P wave is totally blocked in the AV node
-ratio = 3:2, 4:3, 5:4 (one less)


2nd Degree AV block-Mobitz

-series of cycles consisting of one normal P-QRS-T cycle preceded by a series of paced P waves that fail to conduct through the AV node
-the poorer the conduction ration (higher) the worse the prognosis
**w/ Mobitz every cycle missing a QRS has a regular punctural P wave (NEVER PREMATURE)


Differentiating 2:1 Wenchebach vs 2:1 Mobitz

Wenchebach= PR interval is lengthened and QRS is normal

Mobitz= PR interval is normal but the QRS is widened

**if meets both criteria may have to do val maneuver to differentiate: if wenchebach causes more cycles/series; if mobitz causes 1:1 conduction


3rd degree AV block-Junctional Focus

-normal (narrow) QRS's
-ventricular rate = 40-60/min


3rd degree AV block-Ventricular Focus

-PVC-like QRS's
-ventricular rate = 20-40/min
**cerebral blood flow is compromised and may cause syncope (Stokes-Adams Syndrome)


Downward Displacement of the Pacemaker

-absence of atrial activity w/ a wide complex bradycardia
-unfavorable prognosis
-can be caused by hyperkalemia


Diagnosis of BBB

widened QRS > .12 seconds (3 small boxes)


Right chest leads

V1 and V2


Left chest leads

V5 and V6


R, R' in a QRS of normal duration

incomplete BBB


Intermittent Mobitz

bock of one bundle branch w/ intermittent block of the other produces an intermittent complete AV block