Atrial Fibrillation (AF/Afib)
Anesthesia Implications
Anesthesia Implications
Cancelled case – If AF is new-onset on the day of surgery, surgery should be postponed (if elective), until the ventricular rate is controlled and/or the patient has been converted back to sinus rhythm.
Reduced cardiac output – A reduction in cardiac output is primarily due to the loss of atrial contraction. Cardiac output is markedly reduced when the patient also has mitral stenosis, hypertension, hypertrophic cardiomyopathy, and/or restrictive cardiomyopathy.
Stroke risk – AF increases the embolic stroke risk 5 times. Prophylactic heparin or low-molecular weight heparin are most often used as the “bridge” to prevent embolic stroke perioperatively.
Bleeding risk – because patients with chronic AF are taking anticoagulants to prevent a stroke. These are typically stopped 3-7 days prior to surgery. The goal is to have the patient to normal coagulation function by the day of surgery.
Bleeding risk with anticoagulants – The most common combination of anticoagulation therapy for this condition is warfarin and a vitamin K antagonist. Warfarin’s therapeutic affects may be reversed using using vitamin K, fresh frozen plasma, or 4-factor prothrombin complex concentrates. Other anticoagulants may include dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), and clopidogrel (Plavix). Dabigatran may be reversed within a few hours by administering Idarucizumab (Praxbind).
Digoxin consideration – If the patient is on digoxin, side effects of this drug may be causing AV block and/or ventricular ectopy
Pathophysiology
This is the most common sustained cardiac dysrhythmia. It is also the most common post-surgical dysrhythmia, which usually manifests in the first 2-4 days after surgery.
The cause may be structural and/or electrophysiologic which results in abnormal impulse generation or propogation. In some cases, atrial fibrillation can be cured by treating what may be the causes: obesity, sleep apnea, hypertension, drug abuse, hyperthyroidism, rheumatic heart disease, ischemic heart disease, COPD, alcohol abuse, pericarditis, pulmonary embolus, and atrial septal defects.
Diagnosed by a lack of a definable P wave AND an irregular R-R wave. Baseline artifact in the EKG can often be confused with Atrial Fibrillation because the R-R wave is not used as a part of the diagnosis.
Most of these patients are symptomatic. The most common of these symptoms is fatigue. Other symptoms include weakness, palpitations, hypotension, syncope, angina, shortness of breath, and orthopnea.
If AF is contributing to hemodynamic instability, cardioversion (biphasic 100-200 Joules) is often prescribed to back to convert the patient back to sinus rhythm.
For patients that have AF resistant to pharmaceutical management and cardioversion, atrial ablation may be indicated. These surgeries are to ablate the electrical pathways believed to be responsible for AF.
Hines. Stoelting’s anesthesia and co-existing disease. 7th edition. 2018.
American Heart Association. 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation. 2014