M103 T3 Symposium sudden death 2 - Steve Koons Flashcards
What is the trigger for arrhytmia?
ectopic activity
What is required in a patient for them to develop arrhytmia?
substrate
trigger
re-entry
wave break
What are the two types of substrate?
structural
electrical
When can ectopic activity occur?
early after depolarisation
short coupling interval
delayed after depolarisation
How does the concept of re-entry lead to sudden death?
it allows a scenario where the usual organised electrical activity of the heart is lost
it is replaced with more chaotic and less stable electrical patterns
leads to clinical arrhythmia and sudden death
re entry
there is a conduction barrier
What is a property of scar tissue?
often it can only propogate an electrical wave in one direction
What is the effect of ectopic activity?
it causes an extra electrical signal to fire off
What would happen if multi directional conduction was allowed to be generated around the conduction barrier?
the two waves would meet on the other side of the conduction barrier
causing the electrical depolarisation to come to an end
What is the role of the area of the heart that allows for uni directional conduction only?
it will stop any wave from generating around that side of the conduction barrier
When might tissue be able to contract again during the refractory period?
when the refractory period is abnormal
when the circuit is made larger
When might tissue be able to contract again during the refractory period?
when the refractory period is abnormal
when the circuit is made larger
when conduction through the conduction barrier loop is slowed again
How might the circuit is made larger?
if there’s a dilatation of chambers within the heart
if there’s large areas of scar tissue which extend the length of the circuit
What might be responsible for the speed of conduction through the conduction barrier loop being reduced?
an area of scar tissue
What three types of conditions can lead to sudden cardiac death?
ischaemic heart disease
structural heart disease
primary arrhythmic SCD
What types of ventricular remodelling may result from ischaemic heart disease?
scar formation myocardial fibrosis coupling dilatation poor function
What is an example of a structural heart disease?
dilated cardiomyopathy
What are the common causes of dilated cardiomyopathy?
idiopathic viral alcohol chemotherapy drugs autoimmune disorders
Which factors are involved in the pathophysiology of dilated cardiomyopathy?
subendocardial myocardial fibrosis
neurohumoral activation
increased sympathetic tone
electrolyte disturbances
What does dilated cardiomyopathy lead to?
ectopy
re-entry
VT / VF
What is a rare type of cardiomyopathy and the most common cause of sudden cardiac death in young athletes?
hypertrophic cardiomyopathy
What type of condition is hypertrophic cardiomyopathy genetically?
autosomal dominant
incomplete penetrance
What is hypertrophic cardiomyopathy caused by?
when there are over 45 mutations in the cardiac muscle sarcomere genes
How does hypertrophic cardiomyopathy occur?
there is a combination of central hypertrophy and an increase in ventricular contractile force
this pulls the mitral valve out of position when the heart contracts
AAR, the whole mitral valve structure moves forward to meet the septum
this blocks the aorta
can lead to a risk of sudden cardiac death
What is the term of the motion that occurs when the whole mitral valve structure moves forward to meet the septum in hypertrophic cardiomyopathy?
systolic anterior motion
What are the symptoms of hypertrophic cardiomyopathy?
may be asymptomatic
exertional chest pain / dyspnoea
exertional syncope
palpitations
What does Arrhythmogenic right ventricular cardiomyopathy lead to?
hypertrophy and dilatation of the right ventricle
How does Arrhythmogenic right ventricular cardiomyopathy present?
asymptomatic
What can Arrhythmogenic right ventricular cardiomyopathy lead to?
sudden cardiac death
Which conditions are associated with Arrhythmogenic right ventricular cardiomyopathy?
exertional syncope
atrial arrhythmia
What are epsilon waves caused by?
postexcitation of the myocytes in the right ventricle
What is a feature of an ECG of a patient with Arrhythmogenic right ventricular cardiomyopathy?
there will be an epsilon wave present
What are examples of structural heart diseases?
aortic stenosis
mitral stenosis
mitral valve prolapse
congenital heart disease
Which syndromes fall under primary arrhythmia?
long QT
Wolff-Parkingson-White
Brugada
Primary VT / VF
What causes Wolff-Parkingson-White syndrome?
the normal anatomical conduction barriers are disrupted.
What type of condition is the Brugada syndrome?
primary arrhytmia
channelopathy
Which ion channel is affected by Brugada syndrome?
the SCN5A channel
What is the effect of the Brugada syndrome?
the expression of SCN5A sodium channels within the heart is not unilateral
AAR, there are particular areas most commonly in the right ventricular outflow tract where there is a discrepancy in conduction velocities.
this means that different layers of heart tissue are able to conduct electrical signals at different speeds.
this means there is potential for re-entry in that area
How is SCD avoided?
identify at risk groups
preventative treatment
family screening where appropriate
resusitation
What preventative treatment is applicable for SCD management?
treat the underlying cause, not just the symptoms
avoid precipitants
anti-arrhythmic medication
implantable defillibrators
Where are Transvenous ICDs positioned?
under the skin between the muscle and the subcutaneous tissue on the left hand side of the chest.
Why are Transvenous ICDs positioned as they are?
allows access the venous system
allows electrodes to be passed into the heart itself
allows the delivery of a defibrillator - a wave of energy to the heart if required
Where are S-ICDs positioned?
the generator and lead are placed either side of the heart, without either component entering the chest cavity
Which groups of patients are best suited for an ICD?
survivors of cardiac arrest patients with Ventricular tachycardia and haemodynamic compromise patients with CHD patients with poor LV function congenital heart disease
