4.6 Ventricular Arrhythmias

Question 1

Demographic risk factors for SCD

Answer 1

• Men
• Old
• African-American/Non-Asian

Question 2

Coronary heart disease risk factors (SCD)

Answer 2

• Hypertension
• Obesity
• Smoking
• Hyperglycaemia/diabetes
• Hypercholesterolaemia
• Family history of SCD/heart disease

Question 3

Specific conditions that can predispose to SCD

Answer 3

• CHD
• AF
• CKD
• Obstructive sleep apnoea
• Cardiomyopathy
• Valvular heart disease

Question 4

Define Sudden Cardiac Arrest (SCA)

Answer 4

• Sudden loss of all heart activity
• Victim is unresponsive, gasping/no breathing
• No perceptible pulse
• Presumed to be of cardiac cause unless another cause (e.g. trauma, drowning etc.) is known

Question 5

Define Sudden Cardiac Death (SCD)

Answer 5

Sudden and unexpected death occurring within an hour of the onset of symptoms/within 24 hours of no symptoms

Question 6

List the eight reversible causes of cardiorespiratory arrest

Answer 6

(4 Hs, 4Ts)
Hypoxia
Hypovolaemia
Hypo/Hyperkalaemia/metabolic disorders
Hypothermia/Hyperthermia
Tension pneumothorax
Tamponade
Toxins
Thrombosis (pulmonary/coronary)

Question 7

What is a ventricular arrythmia?

Answer 7

Abnormal electrical activity that is arising from the ventricles of the heart

Question 8

What are the two types of non-sustained ventricular arrythmias?

Answer 8

• Ventricular ectopic
• Non-sustained ventricular tachycardia (>=3 beats, <30 seconds)

Question 9

What are the three forms of sustainted ventricular arrythmia?

Answer 9

• Ventricular tachycardia
• Ventricular flutter
• Ventricular fibrillation

Question 10

Describe polymorphic VT ECG findings. What often causes it?

Answer 10

• Multiform QRS morphology from beat to beat (widened)
• A sign of ischaemia

Question 11

What syndrome might be incated by oplymorphic VT with long QT interval?

Answer 11

Torsades de Pointes - Ballerina (spinning axis)

Question 12

Describe ECG findings of bidirectional VT. What can cause it?

Answer 12

• Beat-to-beat QRS alternation
• Can be caused by toxins/catecholaminergic polymorphic VT)

Question 13

Describe monomorphic VT ECG findings. What causes it?

Answer 13

• Repeating ECG Shape with tachycardia
• Often caused due to scar/previous infarct (scar slows, widening QRS complex)

Question 14

What can cause a lot of ventricular ectopic beats?

Answer 14

The intrinsic action potential generation of the ventricular myocardium becomes dominant in some areas (increased automaticity), leading to additional beats

Question 15

Describe re-entrant ventricular VT. What type of VT can it cause in terms of ECG findings?

Answer 15

• Circuit of slow and fast conducting myocardium created due to scarring/electrical remodelling
• Can cause monomorphic VT

Question 16

Describe ECG findings of ventricular flutter

Answer 16

Sinusoidal (>300bpm), no isoelectric interval between QRS complexes

Question 17

Describe ECG findings of ventricular fibrillation

Answer 17

• Rapid, grossly irregular electrical activity with marked variability in ECG waveform
• Usually >300bpm

Question 18

List some community interventions for ventricular arrythmias

Answer 18

• Education
• Screening
• Healthy lifestyle
• Basic life support programs
• Community defibrillators
• Recognition of familial risk

Question 19

List some individual interventions for ventricular arrythmia

Answer 19

• Defibrillation: time to shock
• CAD management/risk management
• Internal Cardioverter Defibrillator (ICD)
• Anti-arrythmic medications
• Adherence to guidelines
• Risk scoring systems
• Risk factor management