Clasp Sudden Death Flashcards
What is central dogma?
how genes become protein
What is the function of exons?
part of genetic code that codes for protein
What happens to introns to make a protein?
have to be spliced
What is a promotor sequence?
Part of genetic code that tells RNA transcriptase where to start
What is a missense mutation
point mutation in which a single nucleotide change results in a codon which codes for a different amino acid
What is a conserved gene?
a gene that has remained essentially unchanged through evolution- suggests its unique and essential
How do you correct QT interval for HR?
QT interval/ (square root of R-R)
What cardiac arrhythmia is classically associated with long QT syndrome?
torsades de pointes
What is the defining characteristic of ventricular tachycardia?
QRS complex is greater than 120ms
What drug class is used in the treatment of long QT syndrome?
beta blockers
What is shock?
inadequate organ perfusion leading to inadequate oxygen delivery to tissues and eventually organ failure
What are the 5 types of shock?
hypovolaemic; cardiogenic; septic; anaphylactic and neurogenic
What is the most common infection to cause septic shock?
gram positive bacterial infection
What are examples of causes of neurogenic shock?
spinal cord injury; spinal anaesthesia
What are the common signs of shock?
tachycardia; hypoxia; tachypnoea; increased capillary refill time; decreased UO; pallor; cold
What is Frank Starling’s Law?
increasing end diastolic volume eg preload increased the cardiac output
What is afterload?
resistance LV must overcome to circulate blood
What are the two equations for CO?
CO=HRxSV; CO=MAP/SVR
What is oxygen delivery (DO2) equal to?
CO x CaO2
What makes up arterial oxygen content?
o2 with haemoglobin and dissolved o2
What is the pathogenesis of anaphylactic shock?
sensitised mast cells have IgE on surface which allergen binds to, causing mast cell degranulation and release of inflam mediators eg histamine and PGs, histamine activate H1 receptors on endothelium making hte vessels leaky
How does adrenalide counteract anaphylaxis?
binds to adrenergic receptors on endothelium to close up leaks which reverses process of anaphylaxis
What are the features of cardiogenic shock?
pulmonary oedema and hypotension
What is the key issue in cardiogenic shock?
heart failure
What is the key issue in neurogenic shock?
loss of sympathetic outflow in thoracic spine
What is sepsis 6?
Blood cultures Urine output Fluid challenge Antibiotics Lactate Oxygen
What are the reversible causes of cardiac arrest?
hypovolaemia; hypoxia; hypothermia; metabolic causes; tension pneumo; cardiac tamponade; toxin and thrombus
What heart rhythms is immediate defibrillation appropriate for?
VF and pulseless VT
What is the pathophysiological process underlying cardiac arrest with hypovolaemia?
inadequate stroke volume to maintain cardiac output
What is the pathophysiological process underlying cardiac arrest with hypoxia?
lack of oxygen at amitochondrial level in the myocytes
What is the pathophysiological process underlying cardiac arrest with hypothermia?
slows metabolic activity until enzymes stop functioning
What is the pathophysiological process underlying cardiac arrest with metabolic causes?
destroys electro-chemical balance across cell membrane
What is the pathophysiological process underlying cardiac arrest with tension pneumo?
greater pressure in pleural cavity then in lung squashes the lung
What is the pathophysiological process underlying cardiac arrest with tamponade?
myocardium squashed by pericardial fluid
What is the pathophysiological process underlying cardiac arrest with thrombus?
clot in lungs/coronary vessels preventing flow
What is the treatment for cardiac arrest caused by hypoxia?
oxygen and atropine
What is atropine?
a muscarinic receptor antagonist
What is cardiac arrest?
cardiac output is not sufficient for a palpable carotid pulse
What drugs are used in cardiogenic shock?
inotropes eg dobutamine, milnarone
What are the indicators of severe sepsis?
tachypnoea >=22; hypotension systolic <100mmHg; altered mental status
What are the 3 important types of thrombus causing cardiac arrest?
PE; atherosclerotic plaque; amniotic fluid embolism
What is the time for clinical death to biologic death under normal temp?
3-6mins
What is the difference between biologic death and clinical death?
clinical death is a reversible state
What is the most common cause ofcardiac arrest?
coronary heart disease
How often should adrenaline be given in ALS?
every 3-5mins
When should amiodarone be given in ALS?
after 3 shocks
How deep should cardiac compression be?
5-6cm
How many cardiac compressions be done?
100-120/min
Why should you not lean whilst doing CPR?
to ensure recoil without losing contact between hands and sternum
What can be used to meausre CPR in real time?
waveform capnography
What are the non-shockable rhythms?
PEA and asystole
What are the features of VF?
bizarre irregular waveform; no recognisable QRS complexes; random freq and amplitude
What are the causes of transthoracic impedenace?
electrode size; distance between electrodes; size of chest; hairy chest; poor electrode contact; air trapping
What are the features of monomorphic VT?
broad compex rhythm; rapid rate; constant QRS morphology
What are the clinical signs of a tension penumo?
decreased breath sounds; hyper-resonant percussion note; tracheal deviation
When should cardiac tamponade be considered as a diagnosis?
penetrating chest trauma or after cardiac surgery
what is the immediate post cardiac arrest treatment?
use ABCDE approach; aim for SpO2 of 94-98; normal PaCO2; ECG; treat cause
How long is seconds in one big box on ECG?
0.2s
How long is a small box on ECG?
0.04s
How is HR calculated from ECG?
300/large squares of R-R
What is the normal length of the PR interval?
0.12-0.2s
What is the normal QRS complex interval?
<120ms
How long should QT interval be?
<0.44s - F; <0.4s in M
What suggests a risk of asystole with bradycardia?
recent asystole; Mobitz II AV block; complete heart block with broad QRS; ventricular pause >3s
What is bradycardia often associated with?
shock; syncope; myocardial ischaemia; heart failure
what is the first line treatment for bradycardia
atropine
What is classic picture seen on ECG with atrial flutter?
saw tooth
What is the difference between atrial flutter and atrial fibrillation?
atrial flutter the atria beat regularly and more often than the ventricles whereas AF is irregular and produced in the pulmonary veins not atria
What are the features of AF on ECG?
irregularly irregular QRS; no p waves
What is typical atrial rate in AF?
> 350bpm
What are the features of ventricular tachycardia on ECG?
regular, wide bizarre QRS
What are the features of torsades de pointes on ECG?
200-250bpm; regular or irregular; sinusoidal pattern; twisting of axis
What is torsades de pointes typically associated with?
electrolyte abnormalities
What is the definition of first degree AV block?
regular prolonged PR interval >0.2s
What are the features of type 1 Mobitz?
regularly irregular; increased PR interval until dropped beat then cycle starts over
What are the features of Mobitz second degree?
some p waves not conducted but p waves usually regular and same PR interval for all conducted beats
What are the features of complete heart block on ECG?
regular p waves and regular QRS complexes but no relationship between them
What channel do class I anti-arrhythmic drugs target?
sodium channels
What do class II anti-arrhymic drugs target?
beta-adrenoceptor antagonists- beta blockers
What do class III anti-arrhythmic drugs target?
potassium channels
What do class 4 anti-arrhythmic drugs target?
calcium channels
Which classes of anti-arrhythmics are involved in rate control?
classes II and IV
Waht classes of anti-arrhythmics are invovled in rhythm control?
class I and III
What is the mechanism of action of adenosine?
opens potassium channels in the AV node
What is the MOA of digoxin?
stimulates vagal activity- slows conduction and prolongs refractory period in AV ndoe and bundle of His
Give an example of type 1a agents?
disopyramide and procainamide
give an example of a type Ib agent?
lignocaine
Give an example of a type Ic agent?
flecainide
Give examples of type III agents?
amiodarone and sotolol
When do afterdepolarisations occur?
during phase 3 or 4 of an AP
When are afterdepolarisations more likley to occur?
when the AP duration is abnormally long
When do early afterdepolarisations occur?
during late phase 2 or 3
When do delayed afterdepolarisations occur?
late phase 3 or early phase 4
What arrythmia is asssociated with early afterdepolarisations?
torsades de pointes
What is the most common mutation causing long QT syndrome?
KCNQ1- potassium channel
What arrhythmia is associated with long QT syndrome?
torsades de pointes
What is the difficulty with diagnosing long AT syndrome?
no set length of QT so where is the line drawn- but, as length increases. risk of SCD increases
What is the most common mutation associated iwth Brugada syndrome?
SCN5A-15%: most patietns do not have an ideentified mutation
What is isolated LQT known as?
Romano-Ward Syndrome
What is the LQT associated with deafness known as?
Jerrell Lange-Neilson syndrome
What happens in torsades de pointes?
normal SA beat and the abnormal beat lands when half of heart is refractory and half is ready so ready half receives beat then it passes to the other half which is now ready and etc.
What is LQTS defined as?
QTc >=480ms in repeated ECGs
What are the common triggers for SCD in LQTS?
sleep; stress and exercise
Why is congenital short QT syndrome rarely seen?
not compatible with life- usually die in utero or as baby
What channels are affected in short QT syndrome?
potassium channels
What is seen on ECG with Brugada syndrome?
ST elevation and RBBB in V1-3
What common arrhythmia is associated with Brugada syndrome?
AF
What arrthmias are pts with Brugada syndrome at risk of?
AF; torsades; VF
Why is it difficult to diagnose Brugada syndrome?
intermittnet and changeble ECG changes
What is the problme channel in Brugada syndrome?
sodium channels
What are the triggers for ECG changes in Brugada syndrome?
stress esp. fever; flecainide- blocks sodium channels
How is brugada syndrome inherited?
AD
Which sex is brugada syndrome more common in?
males x8
What is catecholaminergic polymoprhic VT?
adrenaline induced (exaggerated reaction to normal levels of adrenaline) bidirectional VT
How is catecholaminergic polymorphic VT inherited?
AD
What is the treatment for catecholaminergic polymorphic VT?
beta blockers; felcainide; sympathetic denervation surgery
What is the problem in Wolff-Parkinson White syndrome?
accessory pathway between atria and ventricles
Waht is needed to diagnosed WPW syndrome?
palpitations and ECG appearnace
What is a delta wave?
slurred upstroke into QRS; delayed onset into QRS
Waht is seen on ECG with WPW syndrome?
delta waves and short PR interval
What is the most common arrhthmia with WPW syndrome?
atrioventricular reentrant tachycardia- SVT
What is the most common mutation in hypertrophic cardiomyopathy?
sarcomere genes
What is the risk of mortality with HCM?
1% per year risk of mortality
How do you determine whether to give an ICD to HCM patients?
HCM risk calculator
What is affected in dilated cardiomyopathy?
sarcomeres and desmosomes
What is the RF for developing dilated cardiomyopathy?
alcohol
Which gender gets dilated cardiomyopathy more commonly?
males
What happens in arrhythmogenic right ventricular cardiomyopathy?
fibro-fatty replacement of cardiomyocytes- loss of heart structure and change in conduction
What increases your isk of SCD with arrhythmogenic RV cardiomyopathy?
FHx of premature SCD; secerity of RV and LV function; ECG- QRS prolongation; male, older at presentation
What drug is particularly useful in arrhythmogenic RV cardiomyopathy?
sotalol- has some class III anti-arrhytmic action
What is the significance of an intronic variant?
low likelihood of effect
What is the significance of a mutation of the edge of an exon?
splicing error
What is the significance of an exonic variant?
1- change amino acid
2- create stop codon
3- cause frameshift
4- have no effect
What does cDNA stand for?
complementary DNA
What is cDNA?
essentialy mature mRNA sequence with introns removed
What is Loeys Dietz syndrome associated with?
bifid uvula; down-slanting eyes and aortic aneurysms
Above which grading intensity of heart murmurs are thrills present?
4/6
When is JVP raised?
if >4cm above sternal angle
What is a positive abdominojugular reflex?
JVP is raised through 15s compression
What does a positive abdominojugular reflex mean?
RV failure
What is the treatmnet for native valve indolent endocarditis?
amoxicillin and gentamicin
What is the main bug associated with native valve indolent endocarditis?
strep. viridans
what is the treatment for acute native valve endocarditis?
fluclox
What is the main bug associated with native valve acute endocarditis?
s. aureus
What is the treatment for prosthetic vlave of MRSA endocarditis?
vancomycin, rifampicin and gent
What are roth spots?
boat-shaped retinal haemorrhage with pale centre
What vessel is ST elevation in V2-V4 assocaited with?
diagnoal branch of LAD
What vessel is ST elevation in V1 and V2 assocatied iwth?
septal branch of LAD
what vessel is ST elevation in V1-6 associated iwth?
LCA
What vessel is ST elevation in I, AvL, V5 and V6 associated iwth?
circumflex branch of LCA
What vessel is ST elevation in II, III and aVF associated iwth?
RCA
What is first line tx for SVT?
vagal manoeuvres
what is 2nd line for SVT?
adenosine
What is 3rd line for SVT?
beta blocker
What paitnets is adenosine CI in?
asthma
What should be used instead of adenosine in asthmatics?
verapamil
What is used for pharma cardioversion with AF/flutter?
flecainide
what should be used with structural heart damage in pharm cardioversion with AF/flutter?
amiodarone
What is the treatment for sustained VT?
amiodarone
What is hte treatment for torsades?
magnesium sulphate
What is the treatment for bradycardia?
atropine
Which korotkoff sound is systolic pressure?
phase 1
Which korotkoff sound in diastolic pressure
phase 5
What is the mnemonic for classses of antiarrhythmics?
South Beach Polka
What is the difference between the dihydropyridines and non-dihydropiridines?
dihydropirimidines work only on vascular smooth muscle, whereas non- heart and vascular
What does hepb surface antigen mean?
infected with hep b -acute or chronic
what does hep b surface antibody ?
devloped immunity to hep b- natural or vaccinr
What does HBeAg mean?
virus is multiplying
What does hep b core antibody mean?
person has been infected with hep b-dont get with vaccine
What does IgM anti-Hbc mean?
acute infection