Atrial Fibrillation Flashcards
Describe in basic terms what AF is
The SA node is disregulated, sending multiple signals, resulting in fibrillation rather that contraction of the atria, resulting in a loss of atrial kick
What are some risk factors for AF
HTN, heart disease, valvular disease (pt heart in an ineffective state), obesity, diabetes, genetic
Stress on the atria causes……
Tissue stress/ scarring, whereby the cells develop different electrical properties, causing unpredictable electrical signals
Over time paroxysmal AF leads too…..
Over time these episodes lead to more stress on the atria more (calcium overload) leading to progressive fibrosis (scarring) leading to more persistent AF
symptoms of AF
Fatigue, dizzy, SOB, weakness, Palpitations
Why are people in AF at an increased risk of stroke
Atria is quivering, not pumping blood effectively, thus blood in the atria can become stagnant.
When clots dislodge they can end up in the brain
what class of drug is metoprolol
beta blocker
How dose inhibiting B1 help AF
Decreases HR and cardiac output, helping the heart to fill slower and regain an atrial kick, becoming a more effective pump
What receptors are stimulated when fight or flight is activated
Adnergic receptors, alpha and beta
beta blockers block…..
The affect of adrenaline or noradrenaline on the sympathetic nervous system
What is activated when the SNS is activated
Catecholamines, which stimulates adrenaline and noradrenaline to be thrown at organs leading to increase HR and other affects of adrenaline
beta blockers block…
B adrenergic receptors
Treatment if If the patient is moderately compromised
Administer 300 mg of amiodarone IV (over approximately 30 minutes).
Administer a further 150 mg of amiodarone IV over approximately 30 minutes if the ventricular rate remains predominantly greater than 120/minute.
Seek clinical advice if backup is not available for amiodarone, or amiodarone is contraindicated.
Treatment If the patient is not compromised or is mildly compromised(rate over 120)
Administer 50 mg metoprolol tartrate PO.
treatment if patient is compromised
consider the diagnosis because it is very rare for atrial fibrillation or atrial flutter to cause severe compromise.
If the patient can obey commands:
Administer 0.5-1 mg/kg of ketamine IV (up to a maximum of 100 mg) to induce dissociation, and
Cardiovert using maximum joules in synchronised mode. Repeat this once if the rhythm fails to revert.
If the patient cannot obey commands:
Cardiovert using maximum joules in synchronised mode.
Repeat this once if the rhythm fails to revert.
patients suitable for referral to primary care
Those who are known to have paroxysmal atrial fibrillation and the rhythm reverts with metoprolol PO alone.
Those who have chronic atrial fibrillation, but the rate is now controlled with metoprolol PO alone and there are no active symptoms of myocardial ischaemia.
When do we see severe cardiac compromise in AF
It is rare for atrial fibrillation to be the primary cause of severe cardiovascular compromise. For this to occur it usually requires a combination of a very fast ventricular rate (160-200/minute) and severe heart disease.
If the patient is severely compromised, it is much more likely that there is another underlying condition such as septic shock and the diagnosis must be reconsidered prior to providing specific treatment for the dysrhythmia.
treatment of sepsis induced AF
Amiodarone should only be administered in the setting of sepsis if the patient is normotensive, the ventricular rate has failed to settle with 0.9% sodium chloride IV and cooling, and the patient has significant symptomatic myocardial ischaemia.
