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Ventricular arrhythmias

Premature ventricular complex / ectopy

  • When an early ventricular beat occurs prior to the next expected sinus beat.

  • PVC will be broad complex

  • May occur in a regular pattern (bigeminy/trigeminy)

  • Either enhanced automaticity or reentry

  • May result in retrograde atrial activation which can cause a compensatory pause

  • These beats may occur in pairs (couplets), in threes (triplets) or in short runs (non sustained ventricular tachycardia - NSVT)​

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​Causes

  • increase in sympathetic tone

  • stimulants (alcohol, caffeine, tobacco, etc)

  • amphetamine and cocaine abuse

  • MI or ischemia

  • heart failure

  • Associated with scar (non ischemic or ischemic cardiomyopathy)

  • Hypoxia

  • ACidosis

  • Hypokalemia

  • Hypomagnesemia

  • Increased vagal tone

  • Medication related (excess Isuprel, Epinephrine, etc)

  • Idiopathic

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Ventricular ectopy

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​​​​Ventricular couplet​​

​​​​Ventricular triplet​​​​​​

​Ventricular bigeminy​​​

​​​Ventricular trigeminy​​​​​​

Ventricular tachycardia

A focal or reentry arrhythmia originating from a specific part of the ventricle.

Results in a broad complex tachycardia.

May impaur cardiac output with consequent hypotension, collapse and acute cardiac failure.

Cardioversion may required if patient becomes unstable.

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Commonly caused by

  • ​significant cardiac disease

  1. coronary artery disease

  2. cardiomyopathy

  3. LVH, valvular disease, heart failure

  4. ARVC

  • Idiopathic

  • Repolarisation abnormalities

  1. Long/short QT

  2. Brugada

​​​​​​​​​​​​Monomorphic VT​

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​​​​​​​​​​​​​​​Bidirectional VT​

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​​​​​​​​​​​​​​​​​​Polymorphic VT / Torsades de pointes

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Ventricular fibrillation

Ventricular fibrillation (VF) is a ventricular arrhythmia with rapid disorganised and polymorphic QRS complexes.

VF results in the heart being unable to pump effectively due to the extreme ventricular rates and is lethal if left untreated (defibrillation).

Rates between 300-500 bpm.

Amplitude decreases with duration (coarse VF transitions to fine VF)

One of the most common causes of cardiac arrest.

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Causes

  • Coronary artery disease (MI and ischemia)

  • Bradycardia induced

  • Cardiomyopathy

  • Cardiac, medical and traumatic conditions

  • Hypoxia

  • Acidosis

  • Electrolyte imbalance

  • Innapopriately timed cardioversion/electrocution

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