Symposium 2 - Sudden cardiac death Flashcards
List 3 features of a death that can be defined as sudden death
- Natural
- Rapid (either < 1 hour or < 24 hours)
- Unexpected
List four causes of sudden death
–Heart and/or its vessels
–Noncardiac vessels (e.g. stroke or aneurysm)
–Pulmonary system (pulmonary embolism)
–Central nervous system (CNS) (rare seizures in epilepsy)
What is cardiac arrest?
•Definition: a sudden stop in effective blood circulation due to the failure of the heart to contract effectively or at all
•
•NOT the same as a acute myocardial infarct
–Although it can result from AMI sometimes
–AMI = when blood flow to some heart muscle is impaired
•Usually during AMI heart continues pumping, but less effectively
•
•NOT the same as heart failure
–HF = when the circulation is substandard, but the heart is still pumping sufficient blood to sustain life
List three broad categories of arrhythmia causes or risks for arrhythmia?
- Electrical / primary
- Structural
- Iscahemic
List three broad categories of primary arrhythmia?
Channelopathies & ion channel pathologies
Accessory conduction pathways
Unstable myocardium
What is a cardiomyopathy?
- “myocardial disorder in which the heart muscle is structurally abnormal and functions abnormally”
- Pathology when heart size, shape or thickness is abnormal *E
- This excludes heart disease due to coronary artery disease, hypertension, abnormalities of the heart valves, and heart disease present at the time of birth
List four subclasses of cardiomyopathy.
Hypertrophic
Dilated
ARVC - Arrhythmogenic Right Ventricular Cardiomyopathy
Name the most common cyanotic developmental heart defect
Tetralogy of Fallot
List two clinical consequences of Tetralogy of Fallot for the patient.
–Cyanosis, hypoxaemia, low blood O2 sats
–Risk of arrhythmia
–ventricular septal defect
•A hole between the ventricles
–Pulmonary valve stenosis
–Right ventricular hypertrophy
–overriding aorta
•aorta that is misplaced or moved
Explain the concept of substrate vs trigger, and for each list an example?
•Trigger = brief event required to initiate a period of arrhythmia
–Extrasystole
–R on T
–
•Substrate = ongoing, underlying tissue instability that increases triggers OR allows for maintenance and amplification or dysrhythmia
–Electrical or structural defect eg fibrosis, inflammation, ischamia
What is R on T?
Premature electrical activity in a cardiac myocyte
- On the ECG, when a premature QRS complex occurs during the previous T wave
- The T wave is a “vulnerable period”
–During repolarisation of ventricular AP
–Refractory period is ending
What is a PVC (or VPB)?
- Premature ventricular contraction
- Ventricular premature beat
- An event on the ECG where a very and strangely shaped beat occurs in isolation
In terms of activity, what would be the main difference between a pacemaker and an ICD?
- ICDs are triggered for only one beat, when the heart enters a pathological rhythms
- Pacemakers are triggered for every beat
In terms of indication, what would be the main difference between a pacemaker and an ICD?
- ICDs are for pathologically fast rhythms
- Pacemakers are for pathologically slow or stopping rhythms
List two drugs used as antiarrhythmic drugs?
- Beta blockers
- Amiodarone
- Calcium channel blockers
- K+ channel blockers
- There are many others, eg quinidine, mexilitene, adenosine
What are the indications for implanting an ICD?
•cardiac arrest due to ventricular fibrillation
•
•symptomatic heart failure with low LVEF
–Low output heart failure after MI (40 days later)
•
•cardiomyopathies
–Eg Dilated cardiomyopathy
•
•congenital
–Eg Tetralogy of Fallot
•
•Channelopathies
–Eg long QT syndrome
What is a supraventricular arrhythmia?
An arrhythmia whose source is not the ventricular myocardium. Examples are all atrial arrhythmias, arhythmias arising in the AV node or in the bundle of His
What is reperfusion injury?
tissue damage caused when blood supply returns to the tissue after a period of ischemia or hypoxia.
Tissue damage and/or hypoxia lead to electrical irregularities & risk
Contexts *E
Myocardium after PCI
Brain tissue after ischaemic stroke
Cause: the restoration of circulation results in inflammation and oxidative damage
List two broad causes of black outs?
Syncope
Seizures
List two ways that you might attempt to differentiate syncope vs seizures.
Diagnostic tests such as EEG, brain scanning and 24 hour Holter monitoring
Patient history: Seizures tend to be associated with stiffness and unusual postures/ movements
Syncope patients “crumple”, seizure patients “tip over”
However, there are “convulsive syncope” which also features those
In pharmacoeconomics, what is NNT?
Number needed to treat
Average number of patients who need to be treated to prevent one additional bad outcome
What does this ECG show (or what disease is it)?
- Very high voltage (tall)QRS complexes (in V4 and V5)
- This shows a left ventricular hypertrophy, such as hypertrophic cardiomyopathy
What does this CXR show?
- Cardiomegaly.
- The heart has hypertrophied
What is arrhythmogenic re-entry?
- A conduction mechanism that leads to triggering arrhythmia
- The final outcome of re-entry is that there is a circle of conduction
–The circle results in a myocyte being restimulated out of sequence before the true stimulus from the SA node arrives
•Almost invariably, re-entry is caused by a local area of ischaemia that leads to a local delay of conduction and one-way conduction
