Cardiac
Rhythms/Arrhythmias
     (the beginning)
Review of Conduction
      System
Sinoatrial Node
Located in R Atrium
The primary pacemaker
Moderated by vagus nerve
Contains cells which generate regular,
...
Intrinsic Rates
Under certain conditions non-pacemaker cells
 may become pacemakers
 SA node 60-100bpm
 AV node 45-50bpm
 ...
Step by step electrical activation of
                 the heart
•   First half of P wave when sinus
    impulse activates...
Normal electrical activation of the heart


• During PR segment the His –
Purkinje system is activated




•   Activation ...
Electrical activation

• The electrical currents
  generated during
  repolarisation of the
  ventricles are reflected
  i...
The ECG paper
All paper is standard
Records the current produced by the
electrical activity of the heart with regard to
ti...
ECG paper
     • Small square 0.04sec

     • Large square 0.2sec

     • 5large squares 1sec

     • 300larges squares
  ...
Use a systematic approach
• Calculate both atrial and ventricular rates
• Assess for regularity – atrial and ventricular
•...
Rate Calculation
1. Count the number of large squares between two
   QRS complexes. Divide 300 by that number
2. Count the...
P waves
•   Represents atrial depolarization
•   Are they present
•   Is there a P wave before each QRS complex
•   Are th...
QRS complex
•   Represents ventricular depolarization
•   Should be regular
•   If irregular is there a pattern
•   Measur...
T wave
• Represents ventricular repolarisation
• Should be asymmetrical
• Should begin in the same direction as the
  QRS ...
ST segment
• Immediately succeeds
  QRS
• Any elevation or
  depression is abnormal
SINUS RHYTHM: KEY POINTS

• All rhythms that originate in the sinus node will have upright P
  waves. This is because the ...
1. SA NODE INDUCED
          RHYTHM
• SINUS RHYTHM: 60 - 100 BPM

• SINUS BRADYCARDIA: < 60 BPM (FIT
  PEOPLE; POST MI)

•...
Rules for    NORMAL SINUS RHYTHM

Regularity: The R-R intervals are constant; the rhythm is regular.

Rate:        The atr...
Rules for    Sinus Tachycardia

Regularity: The R-R intervals are constant; the rhythm is regular.

Rate:        The atria...
Rules for    Sinus Bradycardia

Regularity: The R-R intervals are constant; the rhythm is regular.

Rate:        The atria...
Rules for    Sinus Arrhythmia
Regularity: The R-R intervals vary; the rate changes with the patient’s
            respirat...
Atrial Fibrillation
ATRIAL FIBRILLATION
• Ectopic stimuli - 350 - 600 BPM
• Random blocking of impulses by AV
  Node
• No P waves (F WAVES: II...
CAUSES
•   UNKNOWN
•   ELECTROLYTE IMBALANCE
•   VALVE DISEASE (MS)
•   CARDIOMYOPATHY
•   COPD/PE
•   THYROTOXICOSIS
•   ...
EFFECTS
• REDUCED CARDIAC OUTPUT – due
  to loss of ‘atrial kick’

• REDUCED CORONARY BLOOD
  FLOW – if fast rate
Rules for     Atrial Fibrillation
Regularity:   The atrial rhythm is unmeasurable; all atrial activity is chaotic.
       ...
TREATMENT
• CARDIOVERSION:SYNCHRONISED
  DC
• MUST BE ANTI-COAGULATED

• IV OR ORAL DRUGS

• PROBLEMS: RISK OF EMBOLI, LVF...
Comparison of Cardiac Output
 Sinus Rhythm v Atrial Fibrillation
VENTRICULAR




ARRHYTHMIA’S
VENTRICULAR
        TACHYCARDIA
• ECTOPIC VENTRICULAR RATE OF 100 -
  200 BPM
• USUALLY REGULAR
• A-V DISSOCIATION
• WIDE ...
Rules for Ventricular Tyachycardia


Regularity:         This rhythm is usually regular, although it can be slightly
     ...
CAUSES
•   MI
•   ISCHAEMIC HEART DISEASE
•   CARDIOMYOPATHY
•   ELECTROLYTE IMBALANCE
•   ESCAPE RHYTHM
•   DRUG INDUCED
TREATMENT
• DEFIBRILLATION IF PULSELESS
• UNDER SEDATION IF SYMPTOMATIC
  (SYNCHRONISED SHOCK)
• ANTI-ARRHYTHMIC DRUGS
• C...
VENTRICULAR
      FIBRILLATION

• DISORGANISED ELECTRICAL
  ACTIVITY IN VENTRICLES
• INCAPABLE OF PUMPING BLOOD
• NO RATE,...
CAUSES
• MI
• MYOCARDIAL ISCHAEMIA

TREATMENT:
• RAPID DEFIBRILLATION
• CPR
• ADRENALINE, AMIODORONE
Cardiac Rhythmdysrhythmia
Cardiac Rhythmdysrhythmia
Cardiac Rhythmdysrhythmia
Cardiac Rhythmdysrhythmia
Cardiac Rhythmdysrhythmia
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Cardiac Rhythmdysrhythmia

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Cardiac Rhythmdysrhythmia

  1. 1. Cardiac Rhythms/Arrhythmias (the beginning)
  2. 2. Review of Conduction System
  3. 3. Sinoatrial Node Located in R Atrium The primary pacemaker Moderated by vagus nerve Contains cells which generate regular, spontaneous action potentials Principal ions involved are Na+ and K+
  4. 4. Intrinsic Rates Under certain conditions non-pacemaker cells may become pacemakers SA node 60-100bpm AV node 45-50bpm His Bundle 40-45bpm Myocardial cells 30-35bpm
  5. 5. Step by step electrical activation of the heart • First half of P wave when sinus impulse activates R atrium • L atrium and AV node have been activated by the time the P wave is completed
  6. 6. Normal electrical activation of the heart • During PR segment the His – Purkinje system is activated • Activation of the IV septum from right to left produces a small q wave • Steep spike of the QRS complex reflects activation of the ventricles – the larger left ventricle dominates
  7. 7. Electrical activation • The electrical currents generated during repolarisation of the ventricles are reflected in the ST segment and the T wave
  8. 8. The ECG paper All paper is standard Records the current produced by the electrical activity of the heart with regard to time and voltage Time – horizontal axis Voltage –vertical axis
  9. 9. ECG paper • Small square 0.04sec • Large square 0.2sec • 5large squares 1sec • 300larges squares = 1min
  10. 10. Use a systematic approach • Calculate both atrial and ventricular rates • Assess for regularity – atrial and ventricular • Are atrial and ventricular activity co-ordinated
  11. 11. Rate Calculation 1. Count the number of large squares between two QRS complexes. Divide 300 by that number 2. Count the number of QRS complexes in six second strip (30 large squares) and multiply by 10 – good for irregular rhythms 3. Count number of QRS complexes in 10 second strip and multiply by 6
  12. 12. P waves • Represents atrial depolarization • Are they present • Is there a P wave before each QRS complex • Are they all the same shape – should be smooth • Usually seen best in lead II - upright • Normal PR interval (adult) 0.12 - 0.2sec
  13. 13. QRS complex • Represents ventricular depolarization • Should be regular • If irregular is there a pattern • Measure the width • Normal QRS width <0.12sec
  14. 14. T wave • Represents ventricular repolarisation • Should be asymmetrical • Should begin in the same direction as the QRS complex • Should be less than 2/3 height of R wave
  15. 15. ST segment • Immediately succeeds QRS • Any elevation or depression is abnormal
  16. 16. SINUS RHYTHM: KEY POINTS • All rhythms that originate in the sinus node will have upright P waves. This is because the electrical current flows from the atria toward the ventricles, which is toward positive electrode in Lead II. • Rhythms that originate in the sinus node include: • Normal Sinus Rhythm • Sinus Bradycardia • Sinus Tachycardia • Sinus Arrhythmia
  17. 17. 1. SA NODE INDUCED RHYTHM • SINUS RHYTHM: 60 - 100 BPM • SINUS BRADYCARDIA: < 60 BPM (FIT PEOPLE; POST MI) • SINUS TACHYCARDIA: 100 - 150 BPM • INFECTION, EXERCISE, LVF, HAEMORRHAGE, PAIN, FEAR
  18. 18. Rules for NORMAL SINUS RHYTHM Regularity: The R-R intervals are constant; the rhythm is regular. Rate: The atrial and ventricular rates are equal; heart rate is between 60 - 100 beats per minute. P Waves: The P waves are uniform. There is one P wave in front of every QRS complex. PRI: The PRI interval measures between .12 and .20 seconds; the PRI measurement is constant across the strip. QRS: The QRS complex measures less than .12 seconds.
  19. 19. Rules for Sinus Tachycardia Regularity: The R-R intervals are constant; the rhythm is regular. Rate: The atrial and ventricular rates are equal; heart rate is greater than 100 beats per minute (usually between 100 and 160 beats per minute). P Waves: There is a uniform P wave in front of every QRS complex. PRI: The PR interval measures between .12 and .20 seconds; the PRI measurement is constant across the strip. QRS: The QRS complex measures less than .12 seconds.
  20. 20. Rules for Sinus Bradycardia Regularity: The R-R intervals are constant; the rhythm is regular. Rate: The atrial and ventricular rates are equal; heart rate is less than 60 beats per minute. P Waves: There is a uniform P wave in front of every QRS complex. PRI: The PRI interval measures between .12 and .20 seconds; the PRI measurement is constant across the strip. QRS: The QRS complex measures less than .12 seconds.
  21. 21. Rules for Sinus Arrhythmia Regularity: The R-R intervals vary; the rate changes with the patient’s respirations. Rate: The atrial and ventricular rates are equal; heart rate is usually in a normal range (60-100 beats per minute) but can be slower. P Waves: There is a uniform P wave in front of every QRS complex. PRI: The PRI interval measures between .12 and .20 seconds; the PRI measurement is constant across the strip. QRS: The QRS complex measures less than .12 seconds.
  22. 22. Atrial Fibrillation
  23. 23. ATRIAL FIBRILLATION • Ectopic stimuli - 350 - 600 BPM • Random blocking of impulses by AV Node • No P waves (F WAVES: II OR V1) • Irregular QRS • Reduced cardiac output, symptoms will depend on ventricular rate
  24. 24. CAUSES • UNKNOWN • ELECTROLYTE IMBALANCE • VALVE DISEASE (MS) • CARDIOMYOPATHY • COPD/PE • THYROTOXICOSIS • STIMULANTS
  25. 25. EFFECTS • REDUCED CARDIAC OUTPUT – due to loss of ‘atrial kick’ • REDUCED CORONARY BLOOD FLOW – if fast rate
  26. 26. Rules for Atrial Fibrillation Regularity: The atrial rhythm is unmeasurable; all atrial activity is chaotic. The ventricular rhythm is grossly irregular, having no pattern to its irregularity. Rate: The atrial rate cannot be measured because it is so chaotic; research indicates that it exceeds 350 beats per minute. If the ventricular rate is below 100 beats per minute, the rhythm is said to be “controlled”; if it is over 100 beats per minute, it is considered to have a “rapid ventricular response”. P Waves: In this arrhythmia the atria are not depolarizing in an effective way; instead they are fibrillating. Thus, no P wave is produced. All atrial activity is depicted as “fibrillatory” waves, or grossly chaotic undulations of the baseline. PRI: Since no P waves are visible, no PRI can me measured.. QRS: The QRS complex measurement should be less than .12 seconds.
  27. 27. TREATMENT • CARDIOVERSION:SYNCHRONISED DC • MUST BE ANTI-COAGULATED • IV OR ORAL DRUGS • PROBLEMS: RISK OF EMBOLI, LVF, ANGINA
  28. 28. Comparison of Cardiac Output Sinus Rhythm v Atrial Fibrillation
  29. 29. VENTRICULAR ARRHYTHMIA’S
  30. 30. VENTRICULAR TACHYCARDIA • ECTOPIC VENTRICULAR RATE OF 100 - 200 BPM • USUALLY REGULAR • A-V DISSOCIATION • WIDE QRS • CONCORDANT IN CHEST LEADS • ABNORMAL CARDIAC AXIS • CAPTURE OR FUSION BEATS MAY BE SEEN
  31. 31. Rules for Ventricular Tyachycardia Regularity: This rhythm is usually regular, although it can be slightly irregular. Rate: Atrial rate cannot be determined. The ventricular rate range is 150-250 beats per minute. If the rate is below 150 beats per minute, it is considered a slow VT. If the rate exceeds 250 beats per minute, it’s called Ventricular Flutter. P Waves: Non of the QRS complexes will be preceded by P waves. You may see disassociated P waves intermittently across the strip. PRI: Since the rhythm originates in the ventricles, there will be no PRI. QRS: The QRS complexes will be wide and bizarre, measuring at least .12 seconds. It is often difficult to differentiate between the QRS and the T wave.
  32. 32. CAUSES • MI • ISCHAEMIC HEART DISEASE • CARDIOMYOPATHY • ELECTROLYTE IMBALANCE • ESCAPE RHYTHM • DRUG INDUCED
  33. 33. TREATMENT • DEFIBRILLATION IF PULSELESS • UNDER SEDATION IF SYMPTOMATIC (SYNCHRONISED SHOCK) • ANTI-ARRHYTHMIC DRUGS • CORRECT IMBALANCES AND STABILISE PATIENT • TREAT CAUSE
  34. 34. VENTRICULAR FIBRILLATION • DISORGANISED ELECTRICAL ACTIVITY IN VENTRICLES • INCAPABLE OF PUMPING BLOOD • NO RATE, NO P OR QRS WAVES • ERRATIC FIBRILLATING WAVY BASELINE
  35. 35. CAUSES • MI • MYOCARDIAL ISCHAEMIA TREATMENT: • RAPID DEFIBRILLATION • CPR • ADRENALINE, AMIODORONE
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