ECG pathology and arrythmia Flashcards by Sarah Wang

define cardiac arrest

sudden cessation of cardiac activity so that the victim becomes unresponsive with no normal breathing and no signs of circulation

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what does BLS stand for

basic life support

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what is basic life support

( resuscitation system that u r tested on)

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what are shockable and non shockable rythems

shockable = ventricular fibrillation (irregular heartbeat of ventricles) and ventricular tachycardia (a heart rate over 100 beats a minute.
non-shockable = systole (no pulse) and pulseless electrical activity PEA

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define fibrilation

irregular, rapid contractions of muscles esp heart

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what is defibrillation

external electrodes n chest apply current that simultaneously depolarise all cells in heart
depolarised cells are ‘refractory’ (cant start another pulse) and then cannot sustain re-entrant arrhythmia

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what is tachycardia

heart rate above 100 bpm

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what are some symptoms of tachycardia

palpitations
light headedness
SOB
sweatiness/nausea

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why is tachycardia bad

reduced filling time (of blood in heart)
increased myocardial oxygen demand
often associated with other effects e.g venoconstriction

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what is a syndromic approach

treatment given based on clinical symptoms without having clear diagnosis

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what does SVT stand for

supra ventricular tachycardia

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what are 3 main causes of SVT

trigger e.g adrenaline
ectopic focus e.g automaticity
re-entrant arrhythmia (due to changed electrophysiological properties of damaged tissue)

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what is re-entrant arrythmia

when a cardiac impulse fails to stop and re-excites the tissues that have recovered from the refractory period.

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where does re-entrant arrythmia occur

AV node

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what is particular about the tissue that comes from atrial epitaphic tachycardia

generates its own action potentials at a faster rate than the SA node

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abnormal connections b/q the atria and ventricles can lead to re-entrant arrythmias

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‘sinus’ tachycardia is typically due to trigger e.g jogging

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what us the approximate conduction of the AV node

150 bpm

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what is cardioversion

Cardioversion is a medical procedure that uses quick, low-energy shocks to restore a regular heart rhythm

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what are vagal manoeuvres

techniques used to increase vagal parasympathetic tone in an attempt to diagnose and treat various arrhythmias.

how can adenosine be used to help arrythmias

adenosine stimulates A1 adenosine receptors in heart
like acetyl choline, adenosine can hyperpolarize cells and prevent propagation of action potentials
adenosine has an extremely short half life os 6 sends as it is rapidly taken up the tissue

what is the cause of atrial fibrilation

poor coronary blood flow leading to damaged myocardial tissue with altered electrophysiological properties
disorganised depolarisation and hence disorganised contraction of left atria
(acute stress can also be factor)

what are some effects of atrial fibirlation

predisposes static blood which can form thrombi
thrombi can move out of heart to lodge in brain and cause stroke

what are the 4 classifications of atrial fibrillation

acute
paroxysmal (recurrent over 7 days)
persistant ( lasts over a year)
permanent (cant be brought back to sinus rhythm)

what is the long term management of atrial fibrilation

anticoagulation - lowers risk of stroke by 60% (blood close doesnt form)

what is a negative to using anticoagulation meds for fibrilation

has increased risk of bleeding

how can taking anticoagulant affect the elderly

can cause subdural haematomas which is where blood collects between skull and surface of brain

what is the aim of rate control drugs

- limit symptoms but can also prevent development of heart filure

why are rhythm control drugs less preferred

patients frequency dont stay in sinus rythm

how would u diagnose acute partial fibrilation

ECG

how does the time frame affect how you would treat someone with AF

- if onset within 48 hours can cardiovert electrically or pharmacologically - if onset over 48 hours patient required anticoagulation to dissolve potential stroek

what is a TOE

trans-oseophaeal ehochardiogram - used to see if there are clots in left atrium

what drug is used for fast AF

rate lowering drugs (beta blockers and digoxin can be used too)

what is bradycardia

heart rate below 60bpm

what are some causes of bradycardia

- lack of stimulus - conduction abnormality - SA node damage - AV node block - bundle branch block fascicular block

define AV block

represents delay/disturbance in transmission of impulse from atria to ventricles

whats the difference between mobitz type 1 and 2 in an AV block (snd degree block)

type 1 = conduction progressively slower with each beat until impulse is completely blocked and cycle starts over type 2 = fixed PR interval but some of the impulses are not conducted to ventricles

what is a 1st degree AV block

impulses reach ventricle but conduction is slow

what is a 3rd degree AV block

no atrial impulses reach the ventricles - heart is reliant on escape rhythms which re typically slow - no associate between P waves and QRS complexes

what can stimulate beta 1 receptors to make heart beat faster and increase stroke volume

isoprenaline

what is an emergency way to treat brachycardia

atropine blocks parasympathetic stimulation of SA and AV node, increasing heart rate

when is temporary pacing favourable

for conditions that temporary pacing will resolve the issue if it doesnt resolve then a permanent pacemaker is the go to (prolonged pacemaker use can form dependency)

what are 2 methods of temporary pacing and their negatives

transcutaneous (external) pacing - can be difficult to capture and monitor - can cause muscle stimulation transvenous (endocardial) pacing - bleeding - infection - myocardial damage - pnemothorax - technical difficulty

what is hyperkalaemia

excess potassium in the blood

what 3 things can cause yperkalaemia

- excess despotism into blood (over correction of potassium deficiency) - reduced excretion capacity (renal failure) - shift out of cells

what are signs of hyperkalaemia on ECG waves

first: narrow, tall T-waves later on: widening QRS and prolonged PR

how can we manage hyperkalaemia

- calcium glutinate (protects myocardium by preventing ventricular fibrillation from occurring) (limited duration but buys time) or - salbutamol nebuliser (can shift extracellular potassium into cells) - insulin dextrose (can shift extracellular potassium into cells) - treat underlying cause - calcium resonium (mops up excess potassium in diet and ensures it isnt absorbed) and low potassium diet

why should calcium gkutinate be given through a larger cannula

it can irritate tissues

how does sodium bicarbonate help hyperkalaemia via chronic kidney disease

CKD causes acid to build up in blood and body exchanges protons for intracellular potassium - this can worsen hyperkalaemia but helps keep blood pH stable and prevent potassium entering blood