M103 T3 Symposium sudden death 1 - Harry Witchel Flashcards
What are the systems that, when affected, can cause sudden death?
Heart and/or its vessels
Non cardiac vessels (stroke or aneurysm)
Pulmonary system (pulmonary embolism)
CNS - rare seizures in epilepsy
What are the disorders leading to risks for sudden cardiac death?
CHD / low LVEF
structural heart disease (e.g. cardiomyopathies)
developmental/genetic structural pathologies of the heart
primary arrhythmia
What are primary cardiac arrhythmias caused by?
mutations in genes primarily encoding ion channels
leads to a fundamental electrical failure of the heart that causes heart failure where it discontinues beating
What is a Cardiac Arrest otherwise known as?
cardiopulmonary arrest
circulatory arrest
What can an acute myocardial infarction sometimes cause?
cardiac arrest
What can happen to the heart during an acute myocardial infarction?
usually it will continue pumping, but less effectively
What are the broad categories of arrhythmia causes?
Electrical (Primary or Arrhythmogenic)
Structural
Ischaemic
What are electrical arrhythmias caused by?
when there are problems with ion channels and electrical issues at cellular level
when there might be extra conduction pathways at the organ level
What are structural arrhythmias caused by?
unusual shape or size of cardiac tissue that changes signal pathway
What are ischaemic arrhythmias caused by?
when the patient has hypoxia
it makes local heart tissue electrically unstable
it effectively changes signal pathway, leading to delays that interfere with cardiac conduction cycle
What can changes to the signal pathway in structural arrhythmias result in?
signal delays that interfere with cardiac conduction cycle
What can changes to the signal pathway in structural arrhythmias result in?
signal delays that interfere with cardiac conduction cycle
What are the causes of primary arrhythmia?
Unstable myocardium
Ion channel pathologies
Accessory conduction pathways
What is an unstable myocardium caused by in a primary arrhythmia?
damaged or hypoxic tissue
What is an example of an unstable myocardium caused by in a primary arrhythmia?
Atrial Fibrillation
What is an example of a channelopathy?
Long QT syndrome
What happens when Accessory conduction pathways malfunction?
sometimes the transmission of electrical signals along the heart goes in the reverse direction
so rather than going from the atria to the ventricles, it goes the other way
If a patient’s QT intervals are longer than normal, what are they at risk of?
primary arrhythmia
If a patient’s QT intervals are longer than normal, what are they at risk of?
primary arrhythmia
What are the consequences of cardiomyopathy?
there is a risk of pumping dysfunction
there is a risk of low output heart failure
there is a risk of conduction abnormalities
Why does cardiomyopathy cause negative effects?
bc the normal pathways of electrical conduction are altered
What are the two types of cardiomyopathy?
Hypertrophic
Dilated
What are other terms for hypertrophic and dilated cardiomyopathy?
hy - concentric
di - eccentric
What are the differences between hypertrophic and dilated cardiomyopathy?
hy - any age or gender
di - most common in 20 - 60 year olds and in males
What causes hypertrophic cardiomyopathy?
Inner LV chamber shrinks
Myocardium thickens
What is an effect of hypertrophic cardiomyopathy?
Sudden death in young athletes
What is an example of a developmental defect in the heart?
Tetralogy of Fallot
What are two examples of developmental defects in the heart?
an extrasystole
a nearby focus of rapid firing
What might be the causes for cardiac tissue becoming a substrate?
a predisposing factor
an electrical defect
What are examples of structural defects in the heart?
fibrosis or inflammation caused by IHD
What are examples of electrical defects in the heart?
genetic or pharmacological problems with ion channels or electrolytes
What happens during an R on T?
a premature QRS complex occurs during the previous T wave
What is the vulnerable period?
the T wave
When does the vulnerable period occur?
During repolarisation of ventricular AP
Refractory period is ending
What is the resulting QRS wave after the vulnerable period?
a premature ventricular contraction
Which conditions are Implanted Electronic Devices mostly used to treat?
bradyarrhythmias
heart block
What is the difference between and an Implanted Electronic Device and an Implantable Cardioverter Defibrillator?
electronic - applies electrical pulses on each beat
cardioverter - applies electrical impulses ONLY when ventricular dysrhythmias detected
When might an implantable cardioverter defibrillator be implanted?
cardiac arrest due to ventricular fibrillation
symptomatic heart failure with low LVEF
Low output heart failure after MI (40 days later)
cardiomyopathies
congenital
What is an example of a cardiomyopathy?
Dilated cardiomyopathy
What is an example of a congenital reason for why an implantable cardioverter defibrillator be implanted?
Tetralogy of Fallot
What is an example of a Channelopathy?
long QT syndrome
What is the effect of antiarrhythmic drugs?
they usually affect ion channel activity or sympathetic drive
What are examples of antiarrhythmic drugs?
Amiodarone
Beta blockers
Which antiarrhythmias are antiarrhythmic drugs used for?
supraventricular arrhythmias
Arrhythmias arising from atria or AV node
Which works least effectively, antiarrhythmic drugs or pacing or ICDs?
antiarrhythmic drugs
What can reperfusion injury lead to?
electrical irregularities
risk of sudden cardiac death
When might there be an increased risk of reperfusion injury?
in the myocardium after percutaneous coronary intervention
in the brain tissue after an ischaemic stroke
How does reperfusion injury occur?
circulation is restored
this results in inflammation and oxidative damage
What are preventative treatments for reperfusion injury?
Cooling
Immunosuppression - to prevent inflammation
Oxygen radical scavengers
How do xxygen radical scavengers work to stop oxygen radicals in reperfusion injury?
they pick up oxygen radicals and and get rid of their electrons
so it prevents the oxygen radicals from causing a chain reaction of damage
What are both syncope and seizures associated with?
a loss of consciousness
the symptoms are described as “black outs”
What can delay the diagnosis of syncope and seizures?
figuring out which condition matches the symptoms bc they’re so similar
Can be difficult to differentiate from a patient’s description
When does syncope occur?
when the heart and the vessels aren’t supplying blood to the brain effectively
What visual effects do seizures tend to be associated with?
stiffness
unusual postures/ movements
patients “tip over”
What visual effects does syncope tend to be associated with?
patients crumple into themselves
How might a seizure or syncope patient present which might make it hard to diagnose?
might have nothing abnormal on examination
How is syncope recognised in a patient?
it might be registered by Holter monitor
How do Holter monitors work?
involves measuring their ECG for either 24 hrs or up to five or seven days
How are seizures recognised in a patient?
an EEG
a brain scan
What does an electroencephalogram involve?
electrodes on the scalp
Why are brain scans used in regard to seizures?
when seizures are caused by underlying structural abnormalities, the brain imaging can sometimes show what might be causing the seizures
Why are brain scans used in regard to seizures?
when seizures are caused by underlying structural abnormalities, the brain imaging can sometimes show what might be causing the seizures
What causes the different ways in which syncope and seizure patients fall?
syn - crumple - bc the brain has lost all power so it loses control of all the muscles
seiz - tip over - bc the brain is over active, patients remain stiff
Which condition features the same effects as a normal seizure?
convulsive syncope
What are two common types of syncope?
Exertional syncope
Vasovagal Syncope
What is Vasovagal Syncope associated with?
Vagal increase (& symp decrease)
vasodilatation
low heart rate
Where in the body are Vasovagal Syncopes triggered from?
centrally - the brain
not triggered at level of heart
What causes Vasovagal Syncope?
the physiological changes in the body that vasovagal syncope is associated with leads to a pressure drop throughout the NS
so blood will stop going uphill against gravity and will not go to the brain
What is the most common form of syncope?
Vasovagal Syncope
What group is Vasovagal Syncope most common in?
in young adults
Where in the body are Vasovagal Syncopes triggered from?
it has neurogenic origin
What does the Number Needed to Treat indicate?
describes how good / bad / effective a particular treatment might be IOT to compare it to other treatments
What happens if a mutation in the gene responsible for a particular autosomal dominant disorder has 95% penetrance?
95% of those with the mutation will develop the disease, while 5% will not
What happens if a mutation in the gene responsible for a particular autosomal dominant disorder has 95% penetrance?
95% of those with the mutation will develop the disease, while 5% will not
