Cardiac Dysrhythmias

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Cardiac Dysrhythmias

• Joseph S. DiPietro, Ph.D., RRT
• For Paramedics
• Fall 2002

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Explanation of the Phases
Phase 0 -- sudden and rapid depolarization and
Na influx Phase 1 -- early incomplete
repolarization slowed by Phase 2 -- the
depolarizing effects of slow Ca overlaps the
repolarization of the Na pump causing the
plateau on this phase Phase 3 -- rapid
repolarization leading to Phase 4 -- resting
state
Phase 1
Phase 2
Phase O
Phase 3
Phase 4
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The waves
P wave --- indicating atrial depolarization PR
Interval -- time from the SA node to the AV
node range 0.12 -0.20 sec QRS Complex --
ventricular depolarization range 0.06 - 0.10
sec ST segment -- early ventricular
repolarization ? 1 mm in a positive or negative
direction, or if elevated above the PR
interval/segment T wave -- ventricular
repolarization
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Normal Sinus Rhythm
Normal waves and intervals rate range 60-100
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Sinus Bradycardia
All waves normal(in this case, ST seg and T
wave elevation) with rate lt 60
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Sinus Tachycardia
All waves normalrates gt 100, and some authors
claim can rise above 180
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Sinus Arrhythmia
All waves essentially normal (in this case the
patient has a BBB) rates are variable, but
rhythm is irregular
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Atrial Fibrillation
No visible P waves atrial rates can reach 600
reentry foci fibrillatory waves present
variable and irregular ventricular rates
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Atrial flutter
No P waves visible saw-toothed F waves
present atrial Rate rage 250-450 with
irregular ventricular rates
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Premature Atrial Complex (PACs)
PAC
Origin, quite near the SA Node P waves of the
PAC will usually not look like the P waves of
previous electrical Activity can be aberrantly
or not conducted at all
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Atrial Tachycardia
While some texts argue a range of 150-250, others
argue that Atrial tachycardia has a range of
140-160 if higher, SVT is Occurring
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Wandering Pacemaker
Different P waves due to gradual shifts between
SA node, Other atrial foci and the AV junction
rhythm can be either Regular or irregular
overall rates usually range from 60 - 100.
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Multifocal Atrial TachycardiaMAT
This is Wandering Atrial Pacemaker with a
ventricular Capture gt 100 beats, we have MAT.
Usually, however, There are only two atrial
sites in MAT
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SVT
Originates above the bifurication of Bundle of
HIS rates usually Above 160 usually applied to
high ventricular rates, but whether Atrial or
junctional origin is not known
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Sinus Arrest (Pause)
Characterized by a cessation of electrical
activity and spontaneous Conversion to NSR
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AV Blocks
1st Degree AV Block
PR interval gt 0.20 sec this case indicates ST
depression
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AV Blocks
2nd Degree, Mobitz TYPE I, Wenkebach
Gradually increasing PR intervals, then a dropped
beat Then repeat
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AV Blocks
2nd Degree, Mobitz TYPE II
Characterized by an unanticipated dropped beat.
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AV Blocks
3rd Degree Complete AV Block
No relationship between P waves and
ventricular capture (QRS)
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Junctional Rhythms
Junctional Escape
If SA node fails, the AV junction takes over P
waves either absent or inverted and can occur
either before, during or after QRS complexesif
continuous, rates will be 40-60
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Junctional Rhythms
Accelerated Junctional
Origin, HIS Bundle w/increased automaticity P
waves either Absent or inverted (retrograde
conduction) usually normal rates are noted
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Junctional Rhythms
Junctional Tachycardia
Also originates in HIS Bundle elevated
ventricular rates, often Associated with
decreased cardiac outputs (due to decreased
preloads)
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Junctional Rhythms
Premature Junctional Contraction
Similar to a PAC, this premature contraction
(complex) Originates at the AV node
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Ventricular Rhythms
Premature Ventricular Complex
A bizarre complex originating in the ventricle,
from ventricular Irritability. If all same,
unifocal If different, multifocal Considered
frequent if more than 6 per minute
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Ventricular Rhythms
Ventricular Bigeminy
A relatively normal PQRST, followed by a PVC, and
then repeats These PVCs are unifocal If every
third beat is a PVC, trigeminy If every fourth
beat is a PVC, quadrigeminy
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Ventricular Rhythms
V-tach
A run of consecutive PVCs If PVCs number
four, but less than 6, this is called a
salvo Two PVCs together is called a couplet
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Ventricular Rhythms
Course V-fib
Fine V-fib
Total loss of electrical organization throughout
the cardiac Conduction system no rate or rhythm
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Ventricular Rhythms
Torsades des pointes
Literally, twisting around the point, this
dysrhythmia appears Initially as V-tach, then
course V-fib, then V-Tach Rx is Defibrillation
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Asystole (Ventricular Standstill)
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Reentry Tachy-Dysrhythmias
Wolff-Parkinson-White Syndrome
(? wave)
Short PR interval
From accessory Bundle of Kent, which connects the
atria w/ventricles, bypassing normal conduction
system Short PR interval w/Delta (?) wave
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Reentry Tachy-Dysrhythmias
Others Lown-Ganong-Levine (LGL) Syndrome--James
Bundle partially Connects atria to lower portion
of AV Node Short PR interval w/o Delta (?) wave
Mahaim Fibers (un-named) Syndrome--these fibers
exist below The AV node and insert the
ventricular wall, bypassing part or all The
ventricular conduction system Normal PR
interval, Prolonged QRS w/Delta (?) wave