1. Select Dysrhythmias and Therapeutic Modalities
J.O. Medina, NP
Education Specialist
Nurse Practitioner
Critical Care & Emergency Services
California Hospital Medical Center

2. Premature Atrial Contractions (PACs)
Rate usually within normal range but depends on underlying rhythm
Rhythm regular with premature beats
P waves premature (occurring earlier than the next sinus P wave), positive in lead II, one precedes each QRS complex, often differ in shape from sinus P waves : may be flattened, notched, pointed, biphasic, or lost in preceding T wave

3. Premature Atrial Contractions (PACs)
PR interval may be normal or prolonged, depending on prematurity of beat
QRS Duration usually less than sec but may be wide (aberrant) or absent, depending on the prematurity of the beat; the QRS of the PAC is similar in shape to those of the underlying rhythm unless the PAC is aberrantly conducted

4. Premature Atrial Contractions (PACs)
PAC is not an entire rhythm - it is a single beat. Therefore identify the underlying rhythm and the ectopic beat(s)
Types
non-conducted or blocked PAC
only P wave with no QRS after it appearing as pause
conducted PAC

5. Premature Atrial Contractions (PACs)
PAC Patterns:
pairs (couplet) : two sequential PAC
“runs” or “bursts” : three or more sequential PACs often called:
paroxysmal (sudden)
atrial tachycardia (PAT)
paroxysmal SVT (PSVT)
atrial bigeminy
atrial trigeminy
atrial quadrigeminy

6. Premature Atrial Contractions (PACs)
Clinical Significance
very common
presence does not imply underlying cardiac disease

7. Atrial Tachycardia Rate 150 - 250 beats/min Rhythm regular
P waves one positive P wave precedes each QRS complex in lead II but the P waves differ in shape from sinus P waves; with rapid rates, it is difficult to distinguish P waves from T waves

8. Atrial Tachycardia
PR interval may be shorter or longer than normal and may be difficult to measure because P waves may be hidden in T waves
QRS duration 0.10 sec or less unless an interventricular conduction delay exists

9. Atrial Tachycardia Clinical Significance
rapid ventricular rate may decrease cardiac output

10. Atrial Flutter
Rate atrial rate / min, typically / min; ventricular rate variable determined by AV blockade
Rhythm atrial regular ; ventricular regular or irregular
P waves no identifiable P waves; saw- toothed “flutter”, “picket fence”
PR interval non measurable
QRS usually < 0.10 sec

11. Atrial Flutter Clinical Significance
is accompanied by a rapid ventricular rate, there is decreased cardiac output; may deteriorate to atrial fibrillation

12. Atrial Fibrillation
Rate atrial rate usually greater than beats/min; ventricular rate variable
Rhythm ventricular rhythm usually irregularly irregular
P waves no identifiable P waves; fibrillatory waves present; erratic, wavy baseline
PR interval not measurable
QRS duration usually< 0.10 sec but may be widened if an intraventricular conduction delay exists

13. Atrial Fibrillation
Types :
controlled
uncontrolled

14. Atrial Fibrillation Clinical Significance
if accompanied by a rapid ventricular rate, there is decreased cardiac output, increased stroke risk

15. Junctional Rhythms AV node Bundle of His AV junction
a group of specialized cells located in the lower portion of the right atrium, above the base of the tricuspid valve
Bundle of His
cardiac fibers located in the upper portion of the interventricular septum; connects the AV node with the two bundle branches
AV junction
the AV node and the nonbranching portion of the bundle of his

16. Premature Junctional Complex (PJC)
Rate usually within normal range but
depends on underlying rhythm
Rhythm regular with premature beats
P waves may occur before, during or
after the QRS ; if visible, the
P wave is inverted in leads II,
III, and aVF

17. Premature Junctional Complex (PJC)
PR interval if P wave occurs before the
QRS, the PR interval will
usually be less than or equal
to 0.12 sec; if no P wave
occurs before the QRS, there
will be no PR interval
QRS duration usually 0.10 sec or less
unless an interventricular conduction
delay exists

18. Premature Junctional Complex (PJC)
May occur in patterns :
couplets
bigeminy
trigeminy
quadrigeminy

19. Premature Junctional Complex (PJC)
Clinical Significance
most individuals with PJCs are asymptomatic; lightheadedness, dizziness, and other signs of decreased cardiac output may be evident if PJCs are frequent; if the patient is taking digitalis, check digoxin level
signs and symptoms of decreased cardiac output may be present because of underlying bradycardic rate and/or SA node dysfunction; if the patient is taking digitalis, check digoxin level

20. Junctional Tachycardia
Rate beats / min
Rhythm regular
P waves may occur before, during, or after the QRS; if visible, the P wave is inverted in lead II, III, and aVF
PR interval if P wave is present before the QRS, usually less than or equal to 0.12 sec; if no P wave occurs before the QRS complex, there will be no PR interval

21. Junctional Tachycardia
QRS duration usually 0.10 sec or less unless an intraventricular conduction delay exists

22. Junctional Tachycardia
Clinical Significance
the more rapid the rate, the greater the incidence of symptoms caused by increased myocardial oxygen demand
signs of decreased cardiac output if patient taking digitalis, check digoxin level

23. Ventricular Rhythms : Overview
Ventricles are efficient pacemaker
the ventricles assumed the pacing responsibility of the heart if :
SA node fails to discharge
impulse from SA node is generated but blocked as it exits the SA node
rate of discharge of SA node is slower than that of the ventricles
irritable site in either ventricle produces an early beat or rapid rhythm

24. Premature Ventricular Complexes (PVCs)
Rate usually within normal range but depends on underlying rhythm
Rhythm essentially regular with premature beats; if the PVC is an interpolated PVC the rhythm will be regular
P waves usually absent or with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST segment or T wave)

25. Premature Ventricular Complexes (PVCs)
PR interval none with the PVC because
the ectopic beat originates in
the ventricle
QRS duration greater than 0.12 sec,
wide and bizarre, T
wave frequently in
opposite direction of the
QRS complex

26. Premature Ventricular Complexes (PVCs)
PVCs may occur in patterns:
Pairs (couplets)
“runs” or “bursts”
bigeminal PVCs
trigeminal PVCs
quadrigeminal PVCs
Uniform PVCs
Multiform PVCs
Interpolated PVCs
R on T PVCs

27. Premature Ventricular Complexes (PVCs)
Clinical Significance
May or may not produce palpable pulses; may be asymptomatic or complain of palpitations, a “racing heart”, skipped beats, or chest or neck discomfort

28. Ventricular Tachycardia
Monomorphic
Polymorphic
Long QT syndrome (LQTS)
acquired (iatrogenic)
congenital (idiopathic)
Normal QT

29. Monomorphic Ventricular Tachycardia
Rate /min
Rhythm essentially regular
P waves may be present or absent; if present, they have no set
relationship to the QRS
complexes, appearing between the QRSs at a rate different from that of the VT
PR interval none

30. Monomorphic Ventricular Tachycardia
QRS duration > 0.12 sec; often difficult to differentiate between the QRS and T wave
Clinical significance
palpitations
SOB
chest pain
LOC if VT prolonged or sustained

31. Torsades De Pointes (TDP)
Rate beats/min;
typically beats/min
Rhythm may be regular or irregular
P waves none
PR interval none
QRS duration > 0.12 sec; gradual
alteration in amplitude and direction of QRS complexes

32. Torsades De Pointes (TDP)
Clinical significance
palpitations
syncope
dizziness

33. Ventricular Fibrillation
Rate can not be determined because
there are no discernible waves or
complexes
Rhythm rapid, chaotic with no pattern
or regularity
P waves not discernible
PR interval not discernible
QRS duration not discernible

34. Ventricular Fibrillation
Types
coarse
fine
Clinical significance
unresponsive
pulseless
apneic

35. Atrioventricular (AV) Blocks : Overview
AV junction
area of specialized conduction tissue that provides electrical links between the atria and the ventricle
delay or interruption in impulse conduction within the AV node, bundle of his, or his purkinje system is called AV blocks
classification
according to degree of block
according to site of block

36. First Degree AV Block Rate usually within normal range but
depends on underlying rhythm
Rhythm regular
P waves normal in size and shape
PR Interval normal in size and shape,
one positive upright before
each QRS
QRS duration usually 0.10 sec or less unless an interventricular conduction delay exists

37. First Degree AV Block Clinical significance
patient usually asymptomatic
first degree AV block that occurs with acute MI should be monitored closely for increasing heart block

38. Second Degree AV Block Type I
Rate atrial rate is greater than the
ventricular rate
Rhythm atrial regular; ventricular
irregular
P waves normal in size and shape,
some P waves are not
followed by a QRS complex

39. Second Degree AV Block Type I
PR interval lengthens with each cycle
until a P wave appears
without a QRS complex; the
PRI after the nonconducted
beat is shorter than the
interval preceding the
nonconducted beat
QRS duration usually 0.10 sec or less but is periodically dropped

40. Second Degree AV Block Type I
Clinical significance
usually asymptomatic

41. Second Degree AV Block Type II
Rate atrial rate is twice the ventricular
rate
Rhythm atrial regular; ventricular regular
P waves normal in size and shape;
every other P wave is
followed by QRS complex
PR interval constant

42. Second Degree AV Block Type II
QRS duration within normal limits if the block occurs above the bundle of his (type I); wide if the block occurs below the bundle if his (type II); absent after every other P wave
Clinical significance
may rapidly progress to complete AV block without warning

43. Complete AV Block Rate atrial rate is greater than
ventricular rate; the ventricular
rate is determined by the origin of
the escape rhythm
Rhythm atrial regular; ventricular
regular; there is no
relationship between atrial
and ventricular rhythms

44. Complete AV Block P waves normal in size and shape
PR interval none - the atria and
ventricles beat
independently of each other;
thus there is no true PR
interval

45. Complete AV Block QRS duration narrow or wide,
depending on the location
of the escape pacemaker
and the condition of the
interventricular conduction system; narrow indicates junctional pacemaker; wide indicates ventricular pacemaker

46. Complete AV Block Clinical significance
signs and symptoms will depend on the origin of escape pacemaker and patient’s response to ventricular rate

47. Questions?
Thank You !