Cardiac Conduction Flashcards

1
Q

Properties of heart cells

A
1.  Automaticity
To spontaneously initiate an action potential
SA node: 60-100/min
AV node: 40-60/min
Purkinjes: 20-40/min
2. Excitability
To respond to an impulse and then generate it’s own action potential
3. Conductivity
To conduct impulses
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2
Q

Depolarization and Repolarization

A
- Depolarization wave
From the SA node to the AV node & over to the LA = P wave
Thru the AV node, Bundle of His, L&R bundle branches, & perkinjes = PR interval
Thru the ventricular wall = QRS
- Repolarization
Of the atrial = hidden
Of the ventricles = T wave
Of the perkinjes? = U wave
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3
Q

Sinus (SA) Node Arrhythmias

A
- Sinus bradycardia (100)
Normal with exertion/fever
Ischemia, hypoemia
Increases myocardial 
workload, decreases 
coronary artery perfusion
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4
Q

Sinus arrest & Sick sinus syndrome

A

Sinus Arrest: Failure of SA node, usually intermittent
Sick Sinus Syndrome: d/t SA node injury,
unknown cause

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5
Q

Premature atrial complexes (PAC)

A

Early depolarization originating in the atria (not SA node)
Common
(premature atrial contraction)

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6
Q

Paroxysmal supraventricular tachycardia (PSVT)

A
  • 140-240/min, sudden onset and cessation
  • d/t ischemia, reentry
  • wolff parkinson white syndrome
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7
Q

Atrial flutter

A
  • Ectopic atrial tachycardia 240-450/min

- d/t reentry

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8
Q

Atrial fibrillation

A
  • Chaotic depolarization with only occasional contraction
  • Paroxysmal/chronic
  • d/t MI, HF
    What is happening in the heart?
  • Quivering muscle
  • Poor emptying of atria
  • Poor filling of ventricle = decreased CO
    How will your patient present?
  • Heart rate will be irregular
  • Pulses will be irregular with varying strength
  • BP will be low
  • All other systems will exhibit the S&S of decreased CO
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9
Q

AV Conduction Arrhythmias (1st degree block)

A

Blocks (1st, 2nd, 3rd degree)
AV node/Bundle of His/bundle branch issue

1st degree Atrioventricular Block
Consistent long PR interval, followed by a QRS

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10
Q

2nd degree block

A
Mobitz Type 1/Wenckebach
- Increasing PR until QRS dropped     
Mobitz type 2
- Occasional dropped QRS
- PR stable
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11
Q

3rd degree block

A
  • No electrical communication between atria and ventricles
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12
Q

Ventricular Arrhythmias (PVC)

A
  • Premature ventricular complexes (PVC)
  • d/t irritability (ischemia/necrosis)
  • common
  • isolated (single)
  • couplet (two-three in a row…not good)
  • bigeminy (every 2nd beat)
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13
Q

Ventricular fibrillation & Asystole

A

Ventricular fibrillation: ventricle is vibrating, no blood can be pumped.
Asystole: when the heart is not doing anything

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14
Q

Cardiac Conduction Diagnostics

A
  • Electrocardiography (ECG)
    12 lead
    16 lead
  • Holter Monitor
    Exercise Stress Test
    Electrophysiologic Studies
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15
Q

Treatments for Conduction Disorders

A

Cardioversion - the person is still conscious

  • Pharmacological (digoxin)
  • Physiologic (precardial thump, cough)
  • Electrical (paddles)

Defibrillation - defibrilating the person
- Electrical

Pacemaker

Surgical
- Ablation/pacemaker/defibrillator

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