Cardiac Dysrhythmia Part 1

Front 1

Etiology: Disturbances in automaticity

Back 1

 Altered rates caused by various pacemaker cells.
 Example: sinus bradycardia

Front 2

Etiology: Disturbances in conduction

Back 2

 Speed at which impulse travels through the SA>AV>Purkinje fibers.
 Example: AV heart block

Front 3

Etiology:  Reentry of impulses

Back 3

 Reactivated muscle for a second time by the same impulse.
 Example: atrial fibrillation

Front 4

Cardiac Dysrhythmias: Risk factors

* pathophysio - atrial kick

Back 4

 Myocardial ischemia: angina and MI
 Hypoxia
 Vagal stimulation (autonomic nervous system)
 Lactic acidosis
 Electrolyte imbalances
 Drug toxicity
 Shock

Front 5

Clinical manifestations

Back 5

 Reduced cardiac output
 Palpitation, dizziness, syncope, pallor, diaphoresis, altered mental status, hypotension / shock, edema, oliguria, SOB, chest pain, fatigue, seizures
 Heart rate below 50 or above 140, very irregular heart rate, or rate that does not change with exercise.

Front 6

Lead Patterns

Back 6

 Electricity travels from the negative electrode to the positive one.
 Lead II
 Right arm or shoulder lead is negative. Left leg or abdomen/lower chest is positive. Third lead is a ground.
 Follows the same direction as an impulse traveling from SA node to ventricles.
 MCL1 is a modification of a 12 lead’s V1 lead.

Front 7

P wave

Back 7

 First upright wave
 Close to atrial contraction

Front 8

QRS wave

Back 8

 3 waves or less
 Q is first downward wave, R is second upright wave, and S is second downward wave.
 Close to ventricular contraction.

Front 9

P-R interval

Back 9

 Space between beginning of P-wave and the beginning of the Q wave (if Q absent, then the R wave)
 Impulse traveling from the SA node into the AV node.

Front 10

ST segment, T wave

Back 10

 Ventricular repolarization

Front 11

EKG analysis basic steps

Back 11

 Calculate heart rate, which should be between 60-100.
 Measure regularity of R waves (R to R interval) and P waves (P to P interval).
 Examine P waves for their preceding each QRS (R wave) and their sameness.
 Measure the P-R interval, which should be between 0.12-0.20 seconds.
 Measure the duration (or width) of the QRS, which should be less than 0.12 seconds.
 Examine the ST segment, which should be neither elevated or depressed.
 Examine the T wave, which should be upright and 1/3 the height of the QRS.

Front 12

EKG paper

Back 12

 EKG paper has small boxes on it.
 As it comes out of the machine, the horizontal axis of the boxes measures time in seconds.
 Each small box represents 0.04 seconds.

Front 13

0.12 seconds or more difference between different R-R intervals

Back 13

rhythm is irregular.

** R waves or QRS complexes are very close to ventricular contraction.

Front 14

P-R interval

Back 14

between 0.12-0.20 seconds.
IF NOT - Indicates a slowing of conduction in the AV node.

Front 15

QRS

Back 15

less than 0.12 seconds.
IF NOT - Indicates a slowing of ventricular conduction.

Front 16

ST segment

Back 16

neither elevated or depressed IF NOT  Indicates abnormal recovery of ventricle.
 Seen in MI and other conditions.

Front 17

T wave

T-wave is ventricular repolarization.

Back 17

should be upright and 1/3 the height of the QRS
ABN:  Upside down or inverted is seen in myocardial ischemia.
 Peaked or flattened T waves are seen in hyperkalemia and hypokalemia.

Front 18

Characteristics of normal sinus rhythm (NSR or SR)

Back 18

Rhythm
 Regular P-P and R-R intervals, varying only up to 3 mm (less than 3 small boxes).
Rate
 60-100 beats / minute
P waves (atrial contraction)
One precedes each QRS (ventricular contraction)
P-R interval: 0.12-0.20 seconds
QRS complex: less than 0.12 seconds
QT interval: less than 0.40 seconds

Front 19

(NSR or SR)Outcome management

Back 19

 Control the dysrhythmia rate.
 Remove the dysrhythmia.
 Reduce potential complications.

Front 20

Atrial dysrhythmias, automaticity: Sinus Tachycardia (ST)

Back 20

Etiology/risk factors
 Heart failure, fluid loss, shock, respiratory distress, drugs, exercise, stress, pain

Clinical manifestations
 ECG: NSR except for HR > 100

Outcome management
 Treat cause, O2, beta blockers

Front 21

Sinus Bradycardia (SB)

Back 21

Etiology/risk factors
 Vagal stimulation (including Valsalva), drugs, MI, hyperkalemia, athletes

Clinical manifestations
 ECG: NSR except for HR < 60

Front 22

Sinus Bradycardia (SB)

Back 22

Outcome management
If symptomatic:
 Treat cause
 Atropine, epinephrine, or dopamine
 Temporary pacemaker

Front 23

Premature atrial contractions (PAC)

Back 23

Etiology/risk factors
 Ectopic foci
 Valve problems, CHF (atrial enlargement)
 Stress, CAD, medications, pulmonary problems
 Palpitation

Clinical manifestations
 ECG: a P wave is early, differ from the other P waves, and an early QRS follows the early P.

Outcome management
 Treat cause, O2

Front 24

Atrial dysrhythmias, reentry of impulses: Atrial Flutter

Back 24

Etiology/risk factors
 Ectopic foci or rapid reentry, with atrial contraction up to 350 times per minute
 CAD, mitral valve disease, PE, cardiac surgery

Front 25

Atrial Flutter: Clinical manifestations/ Outcome management

Back 25

Clinical manifestations
 ECG: inverted or bidirectional, saw-toothed P-waves, with possibly a constant P-wave to QRS ratio such as 2:1 or 3:1 from AV blocking.

Outcome management
 Cardioversion (similar to defibrillation) or
Drugs:
 Convert to NSR: procainamide, flecainide, propafenone, dofetilide, ibutilide
 Slow ventricular response: verapamil, diltiazem, amiodarone, adenosine

Front 26

Atrial Fibrillation

Back 26

Etiology/risk factors
 Rapid chaotic atrial depolarization, up to 700 times per minute.
 No atrial contraction: loss of atrial kick (decreasing cardiac output 20-30%), thrombi formation in atria
 AV node blocking of some impulses
 Apical-radial pulse deficit
 Hypoxia, CHF

Front 27

Atrial Fibrillation: Clinical manifestations

Back 27

Clinical manifestations
 ECG: erratic baseline without P-waves, very irregular R to R intervals

Front 28

Atrial Fibrillation: Outcome management

Back 28

Outcome management
 Anticoagulants for thrombi
 Diltiazem, metoprolol, cardioversion