136 Tachycardia Flashcards

1
Q

Diagram of slow and fast pathways in Sinus, Premature Atrial Beats, AV nodal echo, AVNRT

A
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2
Q

Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

A
  • The myocardium surrounding the AV node is called the transitional zone
    • electrical properties are intermediate between atrial and AV nodal cells
  • This zone can have variable conduction properties leading to different “pathways” of the AV node
    • Fast pathway: Rapid conduction, long refractory period
    • Slow Pathway: Slow conduction, short refractory period

AV nodal reentry initiation

  • Sinus rhythm normally conducts through the fast pathway to the ventricle
  • A premature beat (usually atrial) occurs while the fast pathway is still refractory
  • The slow pathway is able to conduct this beat to the ventricle
  • When the activation reaches the end of the slow pathway, the fast pathway has recovered and can then conduct retrograde (backwards) to the atrium
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3
Q

Paroxysmal Supraventricular Tachycardia (PSVT)

A
  • REGULAR, NARROW-QRS TACHYCARDIA
    • AV nodal reentrant tachycardia (AVNRT)
    • Atrio-ventricular reentrant tachycardia (AVRT)
    • Ectopic atrial tachycardia (AT)
  • Symptoms
    • wNone
    • wHeart Racing
    • wChest discomfort
    • wDyspnea
    • wLoss of Consciousness (syncope)
    • wHeart failure
    • wIncessant tachycardia can cause a tachycardia mediated cardiomyopathy
    • wAborted Sudden Death
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4
Q

Atrioventricular Reentrant Tachycardias (AVRT)

A

AVRT Uses Atrioventricular Accessory Pathways

  • Anomalous muscle bundles that connect the atrium and ventricle across the valve (tricuspid or mitral)
    • Also known as bypass tracts, Kent bundles
    • Congenital but may lose conduction with age
  • Can sometimes be seen on ECG (“preexcitaion” “delta wave”)
    • Ventricle is activated earlier than expected
    • Slurring of QRS complex
  1. Circuit includes the accessory pathway, AV node/conduction system and intervening atrial and ventricular tissue between these structures
  2. Slow conduction zone is usually the AV node
  3. Circuit can spin in either direction
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5
Q

delta wave

A
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6
Q

Atrial Tachycardia + Other atrial atachycardias

A
  • Focal tachycardia confined to the atrium
    • does not require the AV node
  • Can be sustained or not, paroxysmal or incessant
  • Mechanisms
    • Triggered
    • Automatic
    • Micro-reentry: Small circuit that appears focal

Others:

  • Sinus Tachycardias (usually have a physiologic cause)
    • Inappropriate Sinus Tachycardia if no cause
  • Multifocal AT
    • 3 or more P wave morphologies, irregular
    • can be confused with atrial fibrillation
    • usually seen in pulmonary disease
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7
Q

Atrial Fibrillation and Atrial Flutter

A
  • Atrial fibrillation is the most common arrhythmia and comprises about half of all supraventricular tachyarrhythmias seen clinically
  • Atrial flutter comprises about 10%
  • Atrial fibrillation is often seen in patients with atrial flutter
  • Fibrillation: atrial rate >350 bpm, very irregular and disorganized
  • Flutter: atrial rate generally 240-350 bpm, organized an regular
    • Can be slower on antiarrhythmic drugs or after ablation
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8
Q

Atrial Fibrillation Mechanisms (3)

A
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9
Q

Definitions of V Tach (and categories)

A
  • Non-sustained Ventricular Tachycardia: ≥ 3 beats, <30 seconds, hemodynamically tolerated
  • Sustained: > 30 seconds

The significance of ventricular arrhythmia is dependent on the rhythm and the substrate

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10
Q

Idiopathic Ventricular Tachycardia

A
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11
Q

Torsades de Pointes

A
  • Subset of Polymorphic VT
  • Polymorphic VT in setting of long QT interval
  • Translation “twisting of points”
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12
Q

LONG QT Syndrome

A
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13
Q

VENTRICULAR FIBRILLATION

A
  • §Primary
    • §non-reversible causes (cardiomyopathy, congenital electrical disorders)
  • §Secondary
    • §Acute myocardial infarction
    • §Ischemia
    • §Electrocution
    • §Severe electrolyte disturbances
    • §Drugs
  • §Symptoms- syncope/sudden death
  • §Usually does not self-terminate
  • §Treatment
    • §Treat cause, if secondary
    • §Implantable cardioverter defibrillator(ICD)
    • §Agents to control recurrences (mostly in conjunction with ICD)
  • Mechanism
    • •Depends on substrate
    • Cardiomyopathy: Scarring causes reentry
    • Primary electrical abnormalities: Functional reentry (see later slides)
      • Same for secondary VF
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