Atrial Fibrillation Flashcards
What is the pathophysiology of AF?
Irregular spontaneous depolarisation of the cells in the atria causing dyssynchronous atrial contraction which gives the atria a quivering appearance.
What are common AF symptoms?
Irregularly irregular pulse, breathlessness, palpitations, chest discomfort.
What can be done to diagnose AF?
12-lead ECG. If positive will present with no P-waves, a chaotic baseline, and an irregular ventricular rate.
What medicines can be given for treatment of AF?
Rate control - beta-blocker or rate-limiting calcium channel blocker.
What assessments are done after diagnosis with AF?
CHADSVASc (for stroke risk) and ORBIT (for bleeding risk)
What can be prescribed for AF patients with a CHADVASc score of 2 or more.
Anticoagulant.
What are first line anticoagulants?
Direct oral anticoagulants (DOACs) such as apixaban, rivaroxaban, dabigatran, edoxaban.
What is the mechanism of action of DOACs?
Intervene directly in the coagulation cascade by inhibiting clotting factors such as factor Xa and thrombin, thus preventing formation of a clot.
What is the mechanism of action of Warfarin?
Vitamin K antagonist. Prevents the production of vitamin-K dependent clotting factors by blocking epoxide reductase complex in the liver, thus inhibiting vitamin K activation.
What is INR?
Prothrombin time i.e., measure of how long it takes the blood to clot.
What is the ideal INR?
2-3
What can be done to reverse an INR which is too high?
Give patient vitamin K.
What are some common side effects of warfarin?
Bleeding, bruising, heavier/longer periods, rash, and mild hair loss.
What are some red flag side effects of warfarin?
Blood in urine/vomit/sputum/stools, extremely large/dark or unexplained bruises, uncontrolled bleeding, jaundice, skin necrosis.
How should a patient be switched from warfarin to a DOAC?
Stop warfarin and take INR. DOAC can be started when INR is less than 2.
How should a patient be switched from a DOAC to warfarin?
Start warfarin and continue DOAC for 2 days measuring INR. When INR is in range, stop DOAC.
What does a thromboprophylaxis risk assessment cover?
All patients admitted to hospital undergo this risk assessment. It assesses mobility, thrombosis risk, and bleeding risk.
How should warfarin be dealt with before surgery?
Stop 3-5 days prior and give vitamin K the day before to ensure INR is less than 1.5. Patients at high risk of clots can have bridging with a LMWH between stopping warfarin and 24 hours before surgery.
When can warfarin be restarted after surgery?
If hemostasis adequate, resume at normal maintenance dose on evening of surgery or next day.
