1. Cardiac Dysrhythmias
NURS 241
Chapter 36 (p.818)

2. Rhythm Interpretation Questions
Is the rate regular or irregular?
Is the rate slow, regular, or fast?
Are there ‘p’ waves? Do they all look normal and/or the same?
Is there a ‘p’ wave for every QRS complex
Is the PR interval normal
Is the QRS complex normal
Pg. 822 (Table 36-2) Interval durations
Pg. 825 (Table 36-7) Dysrhythmia characteristics

4. Cardiac Cycle & EKG

5. Cardiac Cycle & EKG

6. Determining Heart Rate
1 mm = 0.04 sec (or each individual block)
5 mm = 0.2 sec (or between 2 dark vertical lines)
Rate = 300/#5mm boxes b/w R-to-R
Rate = 1500/#1mm boxes b/w R-to-R
If rhythm irregular… count number of R waves in 6 seconds and multiply by 10 for an estimated rate

7. Before we look at abnormal… Let’s establish the normal… Sinus Rhythm!
Regular rhythm
Rate: Normal, bpm
P waves normal, all look same, one for every QRS
Normal PR interval sec
Normal QRS interval sec

8. Sinus Bradycardia Regular rhythm Rate: Slow, less than 60 bpm
P waves normal, all look same (kind of), one for every QRS
PR & QRS intervals normal
Causes: vagal stimulation, hypothermia, inferior MI, increased ICP, hypothyroid, cardiac meds (beta blockers)
Tx w/ atropine ONLY if pt. symptomatic

9. Sinus Tachycardia Regular rhythm Rate: Fast, greater than 100 bpm
P waves normal, all look same (kind of), one for every QRS
PR & QRS intervals normal
Causes: Fever, pain, physical activity, MI, HF, medications (epinephrine, dopamine), hypovolemia
Tx: address underlying cause, PRN IV beta-blockers

10. Premature Atrial Contractions (PACs)
Atrial ectopy (source outside SA node stimulated beat)
Rhythm: Irregular d/t premature beats
Rate: Varies, typically normal
P waves of PACs may look different
Causes: stress, fatigue, stimulants, hypoxia
Tx: only if symptomatic, beta-blockers

11. Paroxysmal Supraventricular Tachycardia (PSVT)
Regular (occas. slightly irregular) rhythm
Rate: Fast, bpm
P waves often hidden in preceding T wave (if P waves visible- may have abnormal shape)
PR interval typically short, QRS interval normal
Causes: overexertion, stress, stimulants, dig toxicity, CAD
Tx: vagal maneuvers, adenosine, beta-blockers, cardioversion

12. Atrial Flutter Regular rhythm typically
Rate: atrial bpm, ventricular varies
No P waves, only flutter waves, sawtooth appearance
Causes: CAD, HTN, MV disease, chronic lung disease
Tx: beta-blockers, Ca channel blockers, cardioversion, antidysrhythmic Rx, cardiac ablation

13. Atrial Fibrillation
Disorganized atrial electrical activity (multiple ectopic foci)
Rhythm: Irregular
Rate: Varies, atrial bpm
No P waves, only fib waves, normal QRS typically
Causes: CAD, cardiomyopathy, HTN, HF, pericarditis, electrolyte imbalance, post-cardiac surgery
Tx: Control ventricular rate (beta blockers, Ca channel blockers-diltiazem), antidysrhythmics- amiodarone, cardioversion, coumadin if CAF

14. Junctional Rhythm
Rhythm originates from AV node either d/t SA failure or block
Regular rhythm
Rate: Slow, bpm
P waves either buried in QRS or abnormally close to QRS
PR interval either not measurable or less than 0.08
QRS interval typically normal
Tx: If junctional escape rhythm present (alternation b/w SR and Junctional), may give atropine

15. Accelerated Junctional
Regular rhythm
Rate: Normal, bpm
P waves either buried in QRS or abnormally close to QRS
PR interval either not measurable or less than 0.08
QRS interval typically normal

16. Junctional Tachycardia
Regular rhythm
Rate: Fast, great than 100bpm
P waves either buried in QRS or abnormally close to QRS
PR interval either not measurable or less than 0.08
QRS interval typically normal
Causes of junctional rhythms: CAD, HF, cardiomyopathy, electrolyte imbalance, inferior MI, digoxin
Tx accel. Junct. And/or Junct. Tachy.: Digoxin stopped if cause, CA channel blockers, beta blockers

17. First Degree AV Block Regular Rhythm
Rate: typically normal but can be faster/slower
P waves for every QRS, normal in appearance, but…
PR interval is prolonged, greater than 0.2 sec
QRS normal
Causes: MI, CAD, hyperthyroid, digoxin, beta blockers, Ca channel blockers
Tx: removal of causal drug if applicable, monitor for worsening block

18. Second Degree Type 1 AV Block
AKA Wenkebach
Atrial rate regular, normal; ventricular rate irregular and slower
P waves exist, but more P waves than QRS complexes
PR interval gradually increases until a QRS is dropped
QRS interval normal
Causes: digoxin, beta blockers, CAD, may be transient post-MI (or precursor for worsening block)
Tx: If symptomatic- atropine or temporary pacemaker

19. Second Degree Type II AV Block
PR interval is prolonged but constant
QRS waves are periodically dropped
Atrial normal rate & rhythm, Ventricular slower and regular or irregular
More P waves than QRS complexes (2:1 or 3:1)
PR normal or prolonged, QRS widened
Causes: CAD, anterior MI, drug toxicity
Tx: Pt. needs permanent pacemaker b/c often progresses to complete heart block

20. Third Degree Heart Block
AKA Complete Heart Block- no atrial impulses are conducted by ventricle
Atrial rhythm regular, but may appear irregular d/t some hidden Ps
Ventricular rhythm regular, rate slow bpm
P waves exist and “march out” evenly & QRS “march out” evenly, but… *There is no relation between the two *
QRS may be widened
Causes: Severe heart disease, MI, myocarditis, cardiomyopathy, meds
Tx: Percutaneous or Transvenous temporary pacemaker placed until permanent pacemaker can be inserted, Rx to increase HR (epi, dopamine, atropine)

21. Premature Ventricular Contraction (PVC)
Originate from ectopic ventricle foci
Can be unifocal or multifocal
Can be in couplets, or every other beat (bigeminy as above)
Unable to see P PVC, QRS widened & distorted
Causes: stimulants, electrolyte imbalances*, hypoxia, fever, stress, MI, HF, CAD
Tx: Address causal factor, Rx (beta blockers, amiodarone, lidocaine), maybe nothing if pt. asymptomatic

22. Ventricular Tachycardia
Monomorphic (as above) or polymorphic
Ventricular rate bpm, regular or irregular
Wide, distorted QRS complexes
Patient may OR may not have pulse with rhythm
Causes: MI, CAD, significant electrolyte imbalances, CNS disorders, drug toxicity
Tx: If pulse-IV amiodarone, lidocaine, cardioversion
Tx: If PULSELESS- Defibrillation, CPR, see ACLS algorithm

23. Another Type of VTach
Torsades de Pointes or Turning of the Points (type of polymorphic VT)
Causes: long QTc Syndrome, low serum magnesium*, drug toxicity (Haldol)
Tx: IV magnesium sulfate administration & Follow ACLS algorithm

24. Ventricular Fibrillation (Coarse)
Irregular rhythm, non-measurable rate
Ventricles “quivering”, no effective contraction
PULSELESS Rhythm, need to shock & do CPR immediately (see ACLS algorithm)
Causes: MI, HF, during cardiac catheterization, after coronary reperfusion, hypoxemia, acidosis, drug OD
Tx: Follow ACLS algorithm

25. Ventricular Fibrillation (Fine)
Same causes & Tx modalities
Same as coarse VF except energy stores running out and essentially indicating worsening of situation
Next progression… asystole

26. Pulseless Electrical Activity
May see a rhythm on monitor BUT there is NO PULSE
Poor Prognosis unless cause identified & treated
Causes: hypovolemia, hypoxia, metabolic acidosis, hyper or hypokalemia, hypothermia, drug OD, cardiac tamponade, MI, PE, tension pneumothorax
Tx: Follow ACLS algorithm

27. Asystole NO VENTRICULAR ACTIVITY (occas. P waves, nothing meaningful)
Poor Prognosis
NOT a shockable rhythm!
Must keep doing CPR & giving ACLS until a shockable rhythm emerges (if it does)

28. Does this patient have a pulse?