Sudden Cardiac death

Question 1

Causes of sudden cardiac death

Answer 1

heart and/or its vessels
stroke/aneurysm
PE
CNS - seizures

Question 2

Sudden cardiac death

Answer 2

coronary obstruction
arrhythmia/dysrhythmia
Different to an AMI though can result from an AMI sometimes

Question 3

Broad categories of arrhythmia causes

Answer 3

Electrical (ion channels/conduction pathways)
Structural (shape/size of tissue/signal delays)
Ischaemic (hypoxia makes local heart tissue electrically unstable - changes signal pathway)

Question 4

Causes of primary arrhythmia

Answer 4

Unstable myocardium (hypoxic/damaged tissue, e.g. AF)
Ion channel pathologies (long QT syndrome/accessory conduction pathways)

Question 5

Developmental defect associated with higher risk of sudden death

Answer 5

Tetralogy of fallot

Question 6

Substrate and trigger

Answer 6

To have an arrhythmia you need a trigger (e.g. extra beat/atrial flutter) and a substrate (underlying problem)

Question 7

What part of an ECG is the vulnerable peropd

Answer 7

T wave

During repolarisation of ventricular AP –> premature ventricular contraction

Question 8

Indications for implanting an ICD

Answer 8

Cardiac arrest due to ventricular fibrillation
Symptomatic low output  HF
Dilated cardiomyopathy
Congenital
Channelopathies

Question 9

Reperfusion injury

Answer 9

When blood supply returns to tissue after period of ischemia or hypoxia - leads to electrical irregularities
Eg myocardium after PCI, or brain after stroke

Question 10

Vasovagal vs exertion syncope

Answer 10

Vasovagal: most common, vasal increase -> vasodilation & low heart rate, triggered centrally (brain); recurrent; occurs in young adults
Exertional: neurocardiogenic origin or benign

Question 11

Penetrance

Answer 11

The proportion of individuals carrying a particular variant of a gene that also express an associated trait (phenotype)
If a mutation has 95% penetrance, then 95% of those with the mutation will develop the disease