Ventricular Tachycardia Flashcards
define ventriular tachycardia?
a regular broad complex tachycardia originating from the ventricles
rate usually more than 120bpm
define sustained ventricular tachycardia?
ventricular rhythm faster than 100bpm lasting at least 30 seconds or requiring termination early due to haemodynamic instability
define non- sustained ventricular tachycardia?
ectopic ventricular rhythm with wide QRS complex (120 milliseconds or greater), rate faster than 120 bpm, lasting for at least 3 beats that spontaneously resolves in less than 30 seconds.
MEDICAL EMERGENCY
explain the aetiology/ risk factors of VT?
Electrical impulses arise from a ventricular ectopic focus– an ectopic focus is an excitable group of cells within the atria/ventricles which cause a premature heart beat outside the normally functioning circulation i.e. abnormal pacemaker sites
Can impair cardiac output causing hypotension, collapse and acute cardiac failure.
Torsades de pointesis a rare form of ventricular tachycardia. It can self-correct but it can also both lower arterial blood pressure (leading to syncope) and is a precursor to ventricular fibrillation and therefore sudden death. It can be caused by drugs such as tricyclic antidepressants and amiodarone and is also associated with long QT syndrome (a congenital condition), malnutrition and alcohol abuse. It is treated with intravenous magnesium and anti-arrhythmics.
what can cause Torsades de pointes and how can it be treated?
tricyclic antidepressants and amiodarone and is also associated with long QT syndrome (a congenital condition), malnutrition and alcohol abuse. It is treated with intravenous magnesium and anti-arrhythmics.
what is torsades de pointes?
Rare form of VT
It can self correct- but can also both lower arterial blood pressure ( leading to syncope)-> it is therefore a precursor to ventricular fibrillation and sudden death
What are the risk factors for VT?
Coronary heart disease
Structural heart disease
Electrolyte deficiencies (e.g. hypokalaemia, hypocalcaemia, hypomagnesaemia)
Use of stimulant drugs (e.g. caffeine, cocaine)
what are the presenting symptoms of VT?
signs of ischaemic heart disease/ haemodrynamic compromise
Chest pain
palpitations
dyspnoea
dizziness/ syncope
what are the signs of VT?
dependent on degree of haemodynamic stability
Weak pulse
Respiratory distress
Bibasal crackles
Raised JVP
Hypotension
Anxiety
Agitation
Lethargy
Coma
what are the investigations for VT?
ECG
Electrolytes- (e.g. hypo/hyperkalaemia, hypomagnesaemia) derangement can cause arrhythmias
Drug levels- check for DIGOXIN TOXICITY
Cardiac enzymes- troponins and CK-MB to check for recent ischaemic event
why is it important to investigate electrolytes when investigating VT?
hypo/ hyperkalaemia, hypomagnesia derrangement cause arrythmias
what can be seen on the ECG for VT?
can be difficult to distinguish VT and SVT with abberant conduction-> if in doubt treat as VT
May want to do 24 hour ambulatory ECG
Rate= more than 100bpm
broad QRS complexes
AV dissociation
when is ICD considered in the management of VT?
sustained VT causing syncope
sustained VT with ejection fraction less than 35%
previous cardiac arrest due to VT or VF
MI complicated by non-sustained VT
outline the management for VT?
How is torsades de pointes treated?
polymorphic VT-> give magnesium sulphate
