Background: Currently, several medications are recommended for the management of atrial fibrillation with rapid ventricular response in the emergency department including calcium channel blockers, beta blockers and digoxin (the optimal choice is still up for debate). Magnesium sulfate may play a role as a supplemental medication based on its ability to decrease the frequency of sinus node depolarization, prolongation of the refractory period of the atrioventricular node, and acting as a calcium antagonist inhibiting calcium currents in cardiomyocytes. In addition, intravenous magnesium is safe and cheap. Most previous trials on the use of magnesium sulfate have rather small sample sizes or were performed in post-cardiac surgery patients. Also, the exact dose of magnesium used in previous studies varied significantly making it difficult to determine which dose would be the most optimal in these patients. Recently, the LOMAGHI study was just published trying to answer the questions behind many of these issues. Read more →
Tag Archive for: Atrial Fibrillation
Background:There are two trains of thought in using transthoracic direct current cardioversion (DCCV) when it comes to converting atrial fibrillation. The first is an escalating energy approach which allows cardioversion to occur at the lowest energy for each individual patient and potentially decrease post-shock arrhythmias. The second train of thought is to start at the highest energy approach in order to minimize total number of shocks delivered and duration of the procedural sedation. There is a considerable variation in practice that exists as I recently discovered based on conversations on social media. The authors of this study aimed to compare an escalating energy protocol starting at 100J with a non-escalating energy protocol of 200J to establish the efficacy and safety of both practices of cardioversion using biphasic DCCV of atrial fibrillation. Read more →
Background: Amiodarone is a class III antidysrhythmic first released for human use in 1962. As with other drugs in this class, amiodarone acts by blocking potassium channels thus prolonging the action potential. This, in turn, leads to a lengthening of depolarization of the atria and ventricles. The drug spread rapidly through US hospitals as it was touted as “always works, and no side effects,” by it’s pharmaceutical manufacturer (Bruen 2016).
Of course, nothing comes free and soon after the drug became widely used, a multitude of adverse effects became apparent. These included minor issues – sun sensitivity and corneal deposits – to major ones – thyroid dysfunction (hypo- and hyperthyroidism), pulmonary toxicity and liver damage. Additionally, the medication’s mechanism of action wasn’t clean and simple – amiodarone is no known to have sodium-channel blocking (Class I), beta-blocking (Class II) and calcium-channel blocking (Class IV) effects.
Despite the multitude of issues, the drug continued to be used extensively because of it’s purported benefits. The drug was most commonly applied in the Emergency Department (ED) for conversion of atrial fibrillation, conversion of stable ventricular tachycardia and in refractory VF/VT cardiac arrest.
This post dives into the three most common places amiodarone is employed in the ED: cardioverion of atrial fibrillation, cardioversion of VT and in refractory VF/VT cardiac arrest and demonstrates that superior evidence points to better options for management. Read more →
Background: Atrial fibrillation (AF) is one of the most common dysrhythmias encountered in the ED. The management of recent-onset AF and atrial flutter (AFl) in the ED continues to be debated. The discussion centers on whether patients with recent-onset AF should be rhythm controlled (e.g. converted back to sinus rhythm) or rate controlled only. This debate was showcased in a point-counterpoint in Annals of Emergency Medicine in 2011 (Stiell 2011, Decker 2011). The rhythm control supporters argue that AF/AFl is abnormal, worsens quality of life, leads to cardiac remodeling and, in may patients, requires medications for rate control and anticoagulation. The rate control group argues that cardioversion runs the risk of causing a thromboembolic event (i.e. CVA, peripheral arterial occlusion). Thus, it should not be performed until the absence of clot in the left atrium is confirmed (by TEE) or appropriate anticoagulation has occurred. It has long been taught that if the patient has been in AF/AFl for < 48 hours, the risk of developing a clot in the left atrium is negligible and cardioversion may be pursued. However, some recent literature has called this classic teaching into question (Nuotio 2014). Prospective studies looking at outcomes of recent-onset AF/AFl patients after aggressive treatment in the ED are needed to further evaluate the risks of aggressive treatment.
Background: Atrial fibrillation (AF) is a commonly encountered dysrhythmia in the Emergency Department (ED). Atrial flutter is less common but its management is very similar to that of AF. In patients with chronic AF or unknown time of onset and a rapid ventricular response (RVR), rate control and consideration and initiation of anticoagulation therapy are the standard ED approach. Both beta-blockers and calcium channel blockers are commonly used for rate control in the ED but it is unclear whether one of these agents is superior to the other as there is scant high-quality data on the topic (Demircan 2005). Read more →