Essentials for Understanding AFib

atrial fib

Photo taken from http://www.mayoclinic.org/diseases-conditions/atrial-fibrillation/symptoms-causes/dxc-20164936

Atrial fibrillation occurs when multiple atrial ectopic foci cause the atria to contract at an increased rate, typically 380 bpm or more1, 2. This causes erratic quivering of the atria without effective atrial contractions1. As seen in the example below, there are no observable P-waves- this is due to the ineffective atrial contractions and rapid atrial rate. Conduction of the atrial impulses through the AV node is irregular, so the ventricular responses varies1. Ventricular rates may rise to 110-140 or higher, which is called rapid ventricular response or a fib RVR4.

Image result for atrial fibrillation

Photo taken from https://ekg.academy/learn-ekg?seq=8&courseid=312

Atrial fibrillation may be a complication of a myocardial infarction, but is usually due to one of the following: hypokalemia, hypomagnesemia, digitalis toxicity, cor pulmonale, hypertension, hypoxia, or pericarditis1, 2. A fib is seen in 25%-30% of patients after cardiac surgery- the most common arrhythmia observed following open heart surgery2. The manipulation of cardiac tissue during the operation can irritate the heart making it vulnerable to arrhythmias.

A fib can be dangerous because it compromises cardiac hemodynamics and increases the risk of clot formation due to turbulent blood flow2. Left atrial clot formation could lead to systemic thromboembolism or stroke2. A rapid ventricular rate may compromise ventricular filling and coronary artery blood flow until an individual may experience syncope, lightheadedness, angina, pulmonary edema, or hypotension1. Individuals may also complain of palpitations, shortness of breath, or anxiety3.

I mentioned hypokalemia and hypomagnesemia as common causes- check your patient’s electrolytes because if they go into AF, this is an easy fix! 2 g IV magnesium sulfate is a benign and effective means of treatment with a 60% conversion rate within 4 hours4. Electrolyte repletion may not be adequate enough to convert back to a normal sinus rhythm, so if a patient is stable, treatment will involve three aspects- rate control, rhythm control, and anti-coagulation2.

Rate control: If your patient is already on an oral beta-blocker, an additional IV dose may be given if the ventricular response is greater than 100 bpm. IV Metoprolol (discussed in this post here) is the preferred choice. IV Metoprolol has been found to be effective in converting patient’s back to normal sinus rhythm 50% of the time2. Slower rates (<100 bpm) can be managed by increasing doses of oral metoprolol2.

Image result for intravenous and oral metoprolol

Rhythm control: Amiodarone is especially useful in patient’s with borderline hemodynamics and more compromised LV function because it has no negative inotropic effects (doesn’t weaken the force of contraction)2. A 150 mg Amiodarone bolus is given over 15-30 minutes and oral amiodarone may also be added to their daily medications for prophylaxis2.

Image result for amiodarone bolus

Anti-coagulation: Heparinization should be considered for patients with recurrent or persistent atrial fibrillation to minimize the risk of stroke from embolization of left atrial thrombus5. Anti-coagulation with heparin or oral anti-coagulation is appropriate when AF persists for over 48 hours6, 7.

Image result for heparin iv

Okay, story time… I remember the first time I had a patient go into a fib. I just got off orientation, so obviously I was ready to handle any challenge thrown my way (lol). The NP ordered 4 different IV medications that I needed to hang and, of course, they weren’t compatible. Even better, their second IV had just blown right before this. I must’ve walked under a ladder or passed a black cat on my way to work. I was nervous, but the nurses and techs around me were amazing and helped me through it. The best advice I can give is to remain calm and not be afraid to ask for a hand. Not every situation is urgent, but when it is, you’ll be thankful for your coworkers passing you IV bags or helping you start a new IV. You might be freaking out on the inside, but take a deep breath, get a set of vitals and an EKG (on the patient, not you), and assess their symptoms. Then contact the provider to let them know the patient is a fib and don’t forget to add in their vitals and whether they are symptomatic or not. Nothing feels better than when they convert back to a normal sinus rhythm and you can say you fixed them!

  1. University of Maryland Medical Center Office of Clinical Practice and Professional Development. (2014). Introduction to cardiac rhythm interpretation (6th).
  2. Bojar, R. M. (2016). Manual of perioperative care in adult cardiac surgery (5th). West Sussex, UK: Wiley-Blackwell
  3. http://emedicine.medscape.com/article/151066-overview
  4. Gullestand, L, Birkeland, K, Molstad, P, Hoyer, M. M., Vanberg, P, Kjekshus, J. (1993). The effect of magnesium versus verapamil on supraventricular arrythmias. Clin Cardiol; 16: 429-34.
  5. Lahtinen, J, Biancari, F, Salmela, E, et al. (2001). Postoperative atrial fibrillation is a major cause of stroke after on-pump coronary artery bypass surgery. Ann Thorac Surg; 77: 1241-4.
  6. Salamon, T, Michler, R. E., Knott, K. M., Brown, D. A. (2003). Off-pump coronary bypass grafting does not decrease the incidence of atrial fibrillation. Ann Thorac Surg; 75: 505-7.
  7. Singer, D. E., Alerts, G. W., Dalen, J. E., et al. (2008). Antithrombotic therapy in atrial fibrillation: American College of Chest Physicians evidence-based clinical practice guidelines (8th ed.). Chest; 133: 546S-92S.
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Categories: Cardiac A&P

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