1. Stephanie Sutton RN, CNRN
CARDIAC REVIEW
Stephanie Sutton RN, CNRN
January 2014

2. Cardiac Conduction

3. Measurements Baseline – Isoelectric line Wave above baseline (+)
Wave below baseline (-)
Cardiac cycle = a single heartbeat
Consists of P, Q, R, S, T & Baseline
Measured from beginning of one P wave to the beginning of the next P wave

4. P Waves Normal = well rounded and 2 small boxes or less in height
Abnormal
Peaked – enlargement of right atria
Notched – enlargement of left atria
Negative or absent – electrical conduction initiated from AV junction
Bisphasic or diphasic – enlargement of both atria – only seen with a 12 lead

5. PR Interval
Measured from beginning of P wave to the beginning of next deflection on baseline
Normal 0.12 to 0.20 seconds (3-5 small graph squares)
Abnormal PRI – disturbance in the electrical conduction pathway

6. QRS Complex Normal <0.12 second (3 small boxes)
>0.12 indicates a disturbance in the electrical conduction pathway

7. ST Segment Portion from end of the S wave to beginning of T wave
May be flat, elevated, or depressed
Only used diagnostically in 12-lead EKG

8. T Wave May be above or below the isoelectric line
T wave > half the height of QRS complex = elevated or peaked – may indicate ischemia of cardiac muscle
Depressed or Inverted T wave follows an upright QRS complex, but is below the isoelectric line – usually indicative of previous cardiac ischemia
Flat T wave, or bisphasic/diphasic (seen both above and below isoelectric line) could indicate ischemia or changes in K+ levels

9. P to P Intervals R to R Intervals
Length of time from one P wave to the next P wave
R to R interval
Length of time from the peak of one R wave to the peak of the next R wave
Measurements of these intervals are used to determine if the rhythm of a strip is regular or irregular

10. QT Interval
Measured from the beginning of the QRS complex to the end of the T wave
Normal = less than ½ the R to R interval of that complex and the R wave of the following complex
Prolonged = greater than ½ the R to R interval of that complex and the R wave of the following complex OR > second
Usually indicates a problem with the electrical conduction pathway of the heart

11. Normal Sinus Rhythm
bpm

12. Sinus Bradycardia slower than 60 bpm
May be normal in athletes, or during sleep
Common causes: vomiting, drugs – digitalis, morphine, sedatives
s/s poor cardiac output – pale, cool, clammy skin; cyanosis; dyspnea; confusion or disorientation; dizziness; weakness or faintness; sudden decrease in BP; shortness of breath; n/v; decreased urine output; chest pain; unresponsiveness, increased ICP
May be normal in athletes, or during sleep
Common causes: vomiting, drugs – digitalis, morphine, sedatives
s/s poor cardiac output – pale, cool, clammy skin; cyanosis; dyspnea; confusion or disorientation; dizziness; weakness or faintness; sudden decrease in BP; shortness of breath; n/v; decreased urine output; chest pain; unresponsiveness, increased ICP

13. Sinus Tachycardia 101-150 bpm
As rate of tachycardia increases, P waves frequently hidden in preceding T wave
Causes – pain, fever, anemia, dehydration, hemorrhage, exercise, fear, sudden excitement, anxiety, effects of drugs (atropine, nicotine, caffeine, street drugs)
Causes – pain, fever, anemia, dehydration, hemorrhage, exercise, fear, sudden excitement, anxiety, effects of drugs (atropine, nicotine, caffeine, street drugs)

14. Sinus Arrhythmia
SA node initiates all the electrical impulses, but at irregular intervals
P to P and R to R intervals change with respirations, especially in children and elderly
Rate usually bpm

15. Heart Blocks

16. Practice #1
2nd degree type 1 – Wenkebach

17. Practice #2
1st degree

18. Practice #3
Complete heart block

19. Practice #4
2nd degree mobitz 2

20. Bundle Branch Block
Commonly occurs with CAD
Wide or notched QRS

21. PAC’s contraction occurs before expected Irregular rhythm
May precede PSVT, a fib, a flutter

22. PVC’s Uniform or multiform Usually followed by a compensatory pause
Patient’s may feel “skipped beat”
Irregular rhythm

23. Supraventricular Tachycardia
Rate bpm
P waves can be buried in T waves
Cannot measure PR interval
QRS usually normal
r/t caffeine, nicotine, stress, anxiety
s/s angina, hypotension, light-headed, palpitations, anxiety
r/t caffeine, nicotine, stress, anxiety
s/s angina, hypotension, light-headed, palpitations, anxiety

24. Atrial Fibrillation Atrial rate >= 350 bpm, ventricular rate varies
Rapid, erratic electrical discharge from multiple atrial ectopic foci
No organized atrial depolarization
Absent P waves
No PR interval
Normal QRS
Rapid, erratic electrical discharge from multiple atrial ectopic foci
No organized atrial depolarization

25. Atrial Flutter Atrial rate 250-350 bpm, ventricular rate varies
Flutter waves, saw toothed appearance; may be buried in QRS
PR interval varies
May have widened QRS

26. Junctional Arrythmias
Atria & SA node not functioning properly
Junctional escape rhythm
Rate bpm
P waves absent, inverted, buried, or retrograde
PR interval short, none, retrograde

27. Ventricular Tachycardia
Both:
rate bpm
May be perfusing or non perfusing
Monomorphic
QRS uniform
Polymorphic
QRS varies

28. Torsades de Pointes French for “twisting of points”
Polymorphic VT with long QT intervals
Causes: drugs that prolong QT interval and electrolyte abnormalities
may convert to VF or asystole

29. Ventricular Fibrillation
Chaotic electrical activity – no ventricular depolarization or contraction
No pulse or cardiac output – requires rapid intervention!
Coarse
Fine

30. Pulseless Electrical Activity
Monitor shows electrical rhythm, but no pulse present
May be sinus, atrial, junctional, or ventricular
Causes: trauma, tension pneumothorax, thrombosis, cardiac tamponade, toxins, hypovolemia, hypoxia, hypoglycemia, hypothermia, acidosis, hypo or hyperkalemia

31. Asystole
No electrical activity in ventricles

32. Pacemakers Atrial Ventricular A/V Spike preceeds P wave
Spike followed by QRS
A/V

33. Practice #1
Polymorphic V tach

34. Practice #2
junctional

35. Practice #3 What kind of pacing?
V paced

36. Practice #4
Atrial tachycardia

37. Practice #5
2nd degree type 1 – Wenkebach

38. Practice #6
Bundle branch block

39. Practice #7
Sinus brady