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103 theme 3 > sudden death > Flashcards

sudden death Flashcards

1
Q

what is sudden death

A

natural, rapid, unexpected

not trauma, toxicity, poison or chronic illness

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2
Q

causes of sudden death

A

heart +/- vessels
non cardiac vessels (eg stroke or aneurysm)
pulmonary system (PE)
CNS (rare seizures in epilepsy)

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3
Q

what is sudden cardiac death

A

sudden death due to cardiovascular/coronary vessels

most due to arrhythmias

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4
Q

what are the direct causes of sudden cardiac death

A

coronary obstruction
infarct
embolism
arrhythmia/dysrhythmia

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5
Q

what disorders lead to risks for sudden cardiac death

A

CHD/ low LVEF
structural heart disease-also dev/genetic structural pathologies
primary arrhythmia

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6
Q

what is a cardiac arrest

A

a sudden stop in effective blood circulation due to failure of the heart to contract effectively or at all

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7
Q

is a cardiac arrest the same as a MI or HF

A

No
Can result from AMI (blood flow to heart muscle impaired)
AMI - heart cont pumping but less effectively
HF - circulation substandard, still pumping and sustaining life

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8
Q

what is arrhythmia and dysrhythmia

A

same thing - a variation in the normal beating pattern or rhythm of the heart
usually due to disorganisation of electrical signals running through the heart
can be fast, slow, abnormal

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9
Q

what are the electrical causes of arrhythmia

A

primary or arrhythmogenic.
ion channels and electrical issues at cellular level
extra conduction pathways at the organ level

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10
Q

what are the structural causes of arrhythmia

A

unusual shape or size of cardiac tissue so changes signal pathway, can lead to delays that interfere with conduction cycle

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11
Q

what are the ischaemic causes of arrhythmia

A

hypoxia makes heart tissue electrically unstable

effectively changes signal pathway, leading to delays interfering with conduction cycle

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12
Q

what are the causes of primary arrhythmia

A 
unstable myocardium (damage, hypoxia eg AF)
Ion channels (channelopathies, long QT syndrome)
Accessory conduction pathways
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13
Q

what is cardiomyopathy

A

heart size, shape or thickness is (structure and function) abnormal (not CAD, hypertension, heart valves and HD present at birth)

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14
Q

what are the consequences of cardiomyopathy

A

risk of pumping dysfunction or low output HF

conduction abnormalities

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15
Q

what are the types of cardiomyopathy

A

dilated (eccentric)

hypertrophic (concentric)

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16
Q

what developmental defect is associated with a higher risk of sudden death

A

tetralogy of fallot

associated with higher risk even after childhood surgery

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17
Q

what do you need to have for an arrhythmia

A

trigger and substrate

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18
Q

what is a trigger

A

brief event required to initiate a period of arrhythmia
precipitating event
eg extrasystole or atrial flutter (extra firing)

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19
Q

what is a substrate

A

ongoing, underlying tissue instability that increases triggers or allows for maintenance/amplifications of dysrhythmias

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20
Q

what can substrates be

A

predisposing factor
electrical (eg genetic or pharmacological issues with ion channels or electrolytes) or structural defect (eg fibrosis or inflammation caused by IHD)

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21
Q

what is a R on T (ECG phenomenon)

A

type of potential trigger for arrhythmias
on ECG - premature QRS on previous T wave
T wave is a vulnerable period (repolarisation of ventricular AP, refractory period ending)
Resulting QRS= premature ventricular contraction

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22
Q

what is a pacemaker

A

implanted electronic device - electrodes to stimulate heart
consistently applies impulses for each heart beat
mostly used for bradyarrhythmias and heart block

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23
Q

what is an Implantable Cardioverter Defibrillator (ICD)

A

same as pacemaker but only applies electrical impulses when V arrhythmias detected to protect from fast or uncontrolled rhythms

24
Q

what are indications for implanting an ICD

A

cardiac arrest due to ventricular fibrillation
symptomatic HF with low LVEF (LOHF after MI)
cardiomyopathies - eg dilated
congenital
channelopathies

25
Q

what are antiarrhythmic drugs

A

usually affect ion channel activity or sympathetic drive
eg amiodarone, beta blockers, digoxin for AF
mostly for supraventricular arrhythmias (atria or AV node)

26
Q

what is reperfusion injury

A

tissue damage caused when blood supply returns to the tissue after a period of ischaemia or hypoxia
can lead to electrical irregularities & risk

27
Q

what causes reperfusion injury

A

the restoration of circulation results in inflammation and oxidative damage

28
Q

what are preventative treatments for reperfusion injury

A

cooling
immunosuppression
oxygen radical scavengers

29
Q

how can syncope be distinguished from seizure

A

both loss of consciousness
may have no symptoms when not occurring
Syncope registered by Holter monitor (24 hr ECG)
Seizure registered by EEG (brain imaging is also important)
seizures associated with stiffness/unusual posture
seizures tip and syncope crumple
convulsive syncope can feature both

30
Q

what is vasovagal syncope

A 
Vagal increase (& symp decrease) - vasodilatation and low heart rate
Triggered centrally (ie brain) not at level of heart
most common form of syncope, common in young adults and is recurrent
31
Q

what is exertion syncope

A

Neurocardiogenic origin

Benign

32
Q

what is index case

A

the initial patient in the population of an epidemiological investigation

33
Q

what is the proband

A

In medical genetics, the index case is the case of the original patient that stimulates investigation of other members of the family

34
Q

what is the number needed to treat

A

Statistical measurement of the impact of a medicine or therapy
Averagenumber of patients who need to be treated to prevent one additional bad outcome

35
Q

can arrhythmia be detected

A

genetic screening

36
Q

what is penetrance

A

proportion of individuals carrying a particular variant (or allele) of a gene that also expresses an associated trait (the phenotype)

37
Q

what is incomplete or reduced penetrance

A

do not express trait even though they carry the allele
channelopathies can vary from patient to patient
phenotypes of disease can differ
most diseases are polygenic

38
Q

what is the epidemiology of sudden cardiac death

A

50% all cardiac death
more male
peak 45-75y/o
majority related to coronary disease

39
Q

what are the mechanisms of arrhythmias

A 
substrate (structure or elec)
ectopic activity (early after depolarisation, short coupling interval, delayed after depolarisation)
re-entry
wave break
40
Q

what is re-entry

A

reconduction through an area of unidirectional conduction block
circuit larger, refractory period abnormal, zone of slow conduction - allow for repolarisation

41
Q

how can IHD contribute to arrhythmias

A

acute ischaemia

ventricular remodelling - scar formation, myocardial fibrous, coupling, dilatation, poor function

42
Q

how does an infarction affect the heart

A

zone of infarction to injury to ischaemia which spreads

43
Q

what can cause dilated cardiomyopathy

A 
idiopathic 
viral 
alcohol 
drugs 
autoimmune
44
Q

what is the pathophysiology of dilated cardiomyopathy

A 
myocardial fibrosis
neurohumoral activation
increased sympathetic tone
electrolyte disturbances 
= ectopy, re-entry, VT/VF
45
Q

what is hypertrophic cardiomyopathy

A

most common cause of SCD in young athletes
autosomal dominant, incomplete penetrance
mutation of cardiac muscle sarcomere genes
commonly beta-myosin or troponin-T
LV outflow obstruction, anterior motion of mitral valve, asymmetrical septal hypertrophy

46
Q

what are symptoms of hypertrophic cardiomyopathy

A 
asymptomatic 
exertion chest pain/dyspnoea 
exertion syncope
palpitations 
mechanism of SCD unclear
47
Q

what is arrhythmogenic RV cardiomyopathy

A

30-50% familial
multi-genomic
replace RV myocardium with fibro-fatty tissue
RV hypertrophy and dilation
VT/VF due to re-entry around interstitial fibrosis

48
Q

what are the symptoms of ARVC

A

asymptomatic
exertional syncope
atrial arrhythmias common
epsilon wave on ECG

49
Q

what are other structural causes of SCD

A

aortic stenosis
mitral stenosis
mitral valve prolapse
congenital heart disease (anomalous coronary arteries, Epstein’s anomaly, complex like tetralogy)

50
Q

what are primary arrhythmias

A

non ischaemic
structurally normal heart
syndromes include - long QT, WPW, Brugada, primary VT/VF

51
Q

what is WPW

A 
Wolff-Parkinson-White 
accessory pathway from atria to ventricle
atrial arrhythmia 
ventricular pre-excitation
VTVF
clues on resting ECG
52
Q

what is Brugada

A 
channelopathy 
mostly SCN5A - fast-type sodium channel 
reduce conduction velocities
particularly affects RVOT
prone to VT arising from RVOT
53
Q

How can SCD be treated

A

identify those at risk
preventative treatment - underlying cause, avoid precipitants, anti-arrhythmic meds, ICDs
family screening if appropriate

54
Q

what are the types of ICDs

A

S-ICD - subcutaneous, on breastbone

Transverse ICD - intravascular, tip of lead in contact with right V

55
Q

how are patients selected for an ICD

A 
Cardiac arrest survivors 
VT with haemodynamic compromise 
high risk - CAD, poor LV function, broad QRS
Some HCM, long QT, Brugada, ARVC
Congenital HD
56
Q

What are ICD indications for HCM

A 
survived cardiac arrest
one or more of
VF/spontaneous sustained VT 
Unexplained syncope
LV wall thickness over 30mm
spontaneous NSVT 
abnormal exercise BP
family history of premature sudden death

103 theme 3 (20 decks)

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