Ventricular Fibrillation or Pulseless Ventricular Tachycardia (VF/VT)

Question 1

Ventricular Fibrillation (VF) - Definition

Answer 1

Rapid uncoordinated contraction of individual myocardial cells leading to inability of the myocardium to contract as a whol

Question 2

Pulseless Ventricular Tachycardia (VT)

Answer 2

Myocardial contraction arising from a ventricular impulse, too rapid to sustain adequate cardiac output

Question 3

Goal of Care

Answer 3

High quality CPR cardiac arrest management and return of spontaneous circulation

Question 4

Overview

Answer 4

In VF, myocardial cells are depolarized randomly and independently rather than in the usual sequence by impulses from the Sino-atrial (SA) node through the Atrio-ventricular (AV) node. the heart is often describe as looking like “a bag of worms”

VF is the rhythm most commonly seen in adults who have sudden cardiac arrest

Question 5

Guiding Principle

Answer 5

Early defib is key to success in paramedic witnessed VF or PVT arrest

CPR is essential to prime the myocardium if the arrest was not witnessed by a recognized emergency responder

The standard duration of quality CPR to the first rhythm analysis is 30-60s which is about the time it takes to apply the pads and analyze

Transport and consult w/ the EP if a hospital treatable cause, such has electrolyte disturbance is suspected

Question 6

Specific Therapies - CPR

Answer 6

High quality CPR should be started immediately and interrupted only when absolutely necessary

Best survival occurs when high quality CPR is delivered during the arrest w/ no pause >10s

Question 7

Specific Therapies - Defibrillation

Answer 7

Defibrillation after minimally interrupted CPR gives the best chance of success

If VF recurs, re-initiate defibrillation at the energy level that previously resulted in successful defibrillation

Question 8

Specific Therapies - Epinephrine

Answer 8

EPI 1.0mg is admin’d every 3 mins throughout the cardiac arrest

Current literature suggests limiting EPI to a max of 3-4mg

Best practice is to use 1:10,000 EPI for cardiac arrest

Question 9

Specific Therapies - Amiodarone

Answer 9

Amiodarone is the first line of anti-disrhythmic for VF/VT refractory to deibrillation

• The initial dose is a bolus of 300mg IV. A second bolus of 150mg may be delivered 5-10 mins after the first dose if req’d

Anti-disrhythmic therapy should not interfere w/ other more proven therapies specifically high quality CPR and defibrillation

Question 10

Specific Therapies - Lidocaine

Answer 10

Lidocaine is the second line anti-disrhythmic

• The dose is 1.5mg/kg repeated x 1 if req’d

Question 11

Specific Therapies - Magnesium Sulfate

Answer 11

MgSO4 may be admin’d w/p a physcian’s order when clinically indicated in pts w/ suspected hypomagnesemic states such as w/ alcoholism, anorexia and prescribed diuretic treatment
in pts receiving prescribed anti-arrhythmic medication, particularly sotalol hydrochloride; and where the dysrhythmia is identified as Torsades de Pointes

Question 12

VF/VT - Intervention Guidelines

Answer 12

EMR/PCP
CPR and AED per CAM guidelines

ACP/CCP
Manual defibrillation
Treat precipitating cause

Sympathomimetic
- EPI

Anti-arrhythmic
- Amiodarone
300mg IV bolus; may repeat 150mg bolus in 5-10 mins if req’d
- Lidocaine
1.5mg/kg IV bolus, may repeat x1 if req’d
-Magnesium Sulphate
4g IV

Question 13

Futher Care

Answer 13

In-hospital treatment can include:

• ECMO
• Overdrive pacing
• Correction of underlying medical conditions
• anti-arrhythmic
• cardiac catherization lab
• electrophysiology lab