AF Flashcards
T/F AF is rare below 50 yo?
true but becomes more prevalent with increasing age
what is af?
Abnormal, disorganised electrical signals fired causing the atria to quiver
AF is characterised by rapid and uncoordinated electrical activity in the atria and variable conduction through the AV node, this results in rapid and irregular ventricular contraction. It is often further categorised as
valvular or non valvular
‘valvular’ AF being associated with patients with …?
mitrial stenosis or prosthetic heart valves. All other causes are consider to be ‘non-valvular’
what are the risk factors for AF
hypertension, atherosclerosis and hyperthyroidism, over 65
what are the symptoms of AF
dizziness, palpitations, sob, tiredness
true or false AF can be asymptomatic?
true
a normal HR should be regular and at rest between
60-100bpm
give 2 areas where pulse can be felt to measure HR?
neck
wrist
what can be used to assess for the presence of irregular pulse if there is suspicion of AF?
manual pulse palpitation
if an irregular pulse is detected by manual palpitation was is done next to confirm the diagnosis?
12 lead ecg
what are the 2 approaches of treating af?
rate and rhythm control
if at any stage treatment fails to control symptoms, symptoms reoccur after cardioversion, specialist management is required and referral should be made within how many weeks?
4
ventricular rate can be controlled with what 2 drug classes?
BB or rate limiting CCB
if patients have co existing symptoms associated with acute decompensated HF why should ccb not be used?
-> worsen pulmonary oedema caused by hf
what is next after monotherapy does not work
combination therapy with any two of a
beta-blocker,
diltiazem
or digoxin
why is digoxin only considered if patients do very little physical excercise?
usually only effective for controlling ventricular rate at rest
explain how digoxin works as a cardiac glycoside?
increases force of myocardial contraction and reduces conductivity within av node
what is the aim for blood conc of dogoxin in micrograms/L?
1-2
what is primary method of excretion for digoxin?
renal - so be aware of dosing
why is the effect of digoxin potentiated by both hypokalaemia and hypercalcemia?
directly inhibits the transmembrane Na/K/ATPase exchange pump
cardiac adverse effects of digoxin (toxicity)?
ventricular arrhythmias
av block
atrial arrhythmias
sinus bradycardia
non cardiac adverse effects of digoxin tox?
nausea/ vomiting
anorexia
abdominal pain
visual disturbances
confusion
why are people with af at higher risk of stroke
sluggish blood flow within the fibrillating atria
what tool calculates the risk of stroke?
CHA2DS2VASc
what tool calculates the risk of bleeding?
ORBIT
what does CHA2DS2VASc include as risk predictors?
Congestive HF
HTN
Age
Diabetes
Prior stroke/tia
age 65-74
sex
…
1 point each or age 2 points and 1 point if Female
high risk >1
ORBIT risk predictor… 1 point for each RF
older age
reduced Hb/ anaemia
bleeding Hx
induff kidney func <60
Tx w antiplatelet
…
high risk >4
what are the advantages of DOACs compared to warfarin
predictable pk
allow fixed dosing
no need for blood monitoring
less food and drug interactions
disadvantages of doacs?
mainly renally excreted so dose adjustments
not easy to reverse
cannot use INR as measure of coagulation
what are direct factor Xa inhibitors?
Rivaroxaban
Apixaban
Edoxaban
what is a direct thrombin inhibitor?
Dabigatran
Anticoagulation with a DOAC is recommended in all patients with AF and a CHA2DS2‑VASc score of
2+ taking into account bleeding risk
If the DOAC is not tolerated or not suitable what may be used instead
vit k antagonist like warfarin
what does warfarin inhibit?
clotting factors II, VIII, IX and X
give a benefit of using warfarin as an anticoagulant?
seen with INR 2-3, with low INR increasing risk of stroke and high INR increasing bleeding risk
Prescribing warfarin safely could be challenging why?
NTI
and variability in dose needed to get target INR
what different things can an ecg test for?
heartbeat rate and regularity
heart damage
effect of drugs or devices
how does an ecg work
signal strip is graphic tracing of electrical activity of heart, measures time takes foor initial impulse to fire at sinoatrial node and end in contracting ventricles
what happens at the p wave of an ECG?
atria contract to pump blood into ventricles
What happens in the QRS complex?
ventricles contracting to pump out blood
what does the ST segment show?
end of ventricular contraction
in a patient with AF, what may be seen on an ECG?
many lines for p wave as many fibrillations
what is the t wave?
the resting period of the ventricles
You are clinically screening a drug chart for a patient who is on digoxin. The patient is prescribed 125micrograms daily, the dose range in the BNF is 62.5micrograms to 250micrograms. What can you check to know the dose is ok for your patient?
The pulse, if it is high then a higher dose is needed, if the pulse is low then the dose is too high and needs to be reduced.
Your patient is on apixaban for AF, they are admitted to hospital and are prescribed enoxaparin 40mg SC daily as thromboprophylaxis, is this ok?
NO! if patients are anticoagulated they do not need prophylaxis this is a bleeding risk.
why are people with AF at an increased risk of having a stroke?
NVAF is associated with a x5 increase in the risk of ischaemic stroke. An ischaemic stroke is a result of embolism of a thrombus that forms predominantly within the left atria due to sluggish blood flow within the fibrillating atria.
