VT

Question 1

definition of ventricular tachycardia

Answer 1

>3 successive ventricular extrasystoles (broad QRS complexes >120ms) at a rate of >120/min

Question 2

definition of sustained ventricular tachycardia

Answer 2

Ectopic ventricular rhythm faster than 100 bpm lasting at least 30 seconds or requiring termination earlier due to haemodynamic instability.

Question 3

definition of non-sustained ventricular tachycardia

Answer 3

Ectopic ventricular rhythm faster than 100 bpm lasting for at least 3 consecutive beats but terminating spontaneously in less than 30 seconds.

Question 4

aetiology of sustained ventricular tachycardia

Answer 4

ischaemic cardiomyopathy

idiopathic

Question 5

aetiology of non-sustained ventricular tachycardia

Answer 5

ischemic and non-ischemic heart disease

genetic disorders - long QT syndrome, Brugada syndrome, arrhythmogenic RV cardiomyopathy

congenital heart disease

metabolic problems - drug toxicity or electrolyte imbalance

Question 6

RF of sustained ventricular tachycardia

Answer 6

CAD

acute MI

LV systolic dysfunction

hypertrophic cardiomyopathy

long QT syndrome

short QT syndrome

brugada syndrome

vent pre-excitation

arrhythmogenic RV cardiomyopathy

electrolyte imbalance

drug toxicity

chagas disease

Question 7

RF of non-sustained ventricular tachycardia

Answer 7

CAD

L ventricular systolic function

hypertrophic cardiomyopathy

idiopathic dilated cardiomyopathy

long QT syndrome

Brugada’s syndrome

electrolyte imbalance

drug toxicity

chaga’s disease

Question 8

epidemiology of ventricular tachycardia

Answer 8

approximately 90% of sudden deaths are cardiac - mostly VT or VF

The estimated incidence of non-sustained VT in the general population (both with and without heart disease) is as high as 4% - increases with age

Question 9

sx of VT

Answer 9

sustained

• dizziness
• light headedness
• chest discomfort
• dyspnoea

non-sustained - asymptomatic

Question 10

signs of VT

Answer 10

sustained

• tachycardia
• hypotension
• weak pulse
• syncope/pre-syncope
• airway compromise
• impaired consciousness
• diminished responsiveness

non-sustained - tachy

Question 11

Ix for VT

Answer 11

ECG

electrolytes

trop

creatinine kinase MB

Question 12

ECG for VT

Answer 12

sustained - wide complex tachycardia (QRS ≥120 msec) at a rate ≥100 bpm.

non-sustained - non-sustained ventricular tachycardia with a single QRS (monomorphic) or changing QRS (polymorphic) morphology at cycle length between 600 and 180 ms

Question 13

electrolytes in VT

Answer 13

sustained - low K and low Mg frequently associated with torsades de pointes

non-sustained - normal; low or high K, or low Mg

Question 14

complications of sustained VT

Answer 14

ICD malfunction

V fib

sudden cardiac death

ICD infection

cardiomyopathy

amiodarone induced thyroid dysfunction

Question 15

complications of non-sustained CT

Answer 15

sudden cardiac death

cardiomyopathy

ICD related infection

ventricular fibrillation

Question 16

Px of VT

Answer 16

sustained

• idiopathic - good prognosis. not progressive
• pts with left ventricular systolic dysfunction often have re-entrant rhythms around myocardial scars.
  
  • re-entrant circuits can degenerate to ventricular fibrillation - associated with a high mortality rate

non-sustained - dependent on presence and severity of underlying cardiac disease

Question 17

what is torsades de points

Answer 17

VT

when circuit in action and plane rotates - constantly varying axis

ECG:

• broad complex tachy
• regularly increasing and decreasing amplitudes

Question 18

Mx of VT

Answer 18

1. Attach cardiac monitor and defib
2. assess rhythm - Defibrillate once: 150–360 J biphasic, 360 J monophasic. (Ensure no one is touching patient or bed when defibrillating.)
3. Resume CPR immediately for 2 min, and then return to 2.
4. Administer adrenaline (1 mg IV) after second defibrillation and again every 3–5 min.
5. If ‘shockable rhythm’ persists after third shock, administer amiodarone 300mg IV bolus (or lidocaine).

pts at high risk of recurrent VT should have ICD rather than amiodarone

Question 19

Initial steps in VT management

Answer 19

connect to cardiac monitor, have defib

monitor sats - ox if <90%

correct K adn Mg

check for low CO (clammy, reduced consciousness, BP <90), oliguria, angina, pul oedema

ECG (request CXR) get IV access

Question 20

Mx if haemodynamically unstable VT

Answer 20

synchronised DC shock

correct low K and Mg

amiodarone - 300mg IV over 10-20min

for refractory cases - procainamide or sotalol

Question 21

Mx of haemodynamically stable VT

Answer 21

correct low K and Mg

amiodarone - 300mg IV over 20-60mins - avoid long QT via central line

if fails - DC shock

Question 22

Mx after correction of VT

Answer 22

establish the cause

maintain anti-arrhythmic therapy if needed

if after MI - IV amiodarone infusion for 12-24hr, if <24hr post MI start oral anti-arrhythmic (sotalol if good LV func, amiodarone if not)

prevention - surgical isolation of arrhythmogenic area or ICD

Question 23

Mx fo torsades de pointes

Answer 23

if form congenital long QT syndromes - B blockers

in acquired:

• stop predisposing drugs
• correct low K
• give magnesium sulfate

Question 24

things to do in CPR

Answer 24

check electrolytes, paddle positions and contacts

secure airway - ET tube and high flow ox

continuous compressions and breaths

consider - Mg, bicarb and external pacing

stop CPR and check pulse only if change in rhythm or signs of life

Question 25

causes of torsarde de pointes

Answer 25

often have long QT congenital drugs - antidysrhythmics, tricyclics, antimalarials, antipsychotics