TREATMENT
■ If rapid ventricular response and patient is unstable →electrical cardioversion.
■ Synchronized
■ Start with 50–100J
■ Sedation, if possible
■ Otherwise, rate control with AV-node blocking agents
■ Diltiazem
■ β-Blockers
■ Chemical cardioversion
■ Indicated for acute (<24 hours of symptoms) AFib only or after
transeophageal echocardiogram excludes atrial thrombus.
■ If clot present, patient needs 3–4 weeks of anticoagulation prior to car-
dioversion.
■ Choices include:
■ Amiodarone
■ Ibutilide
■ Procainamide
■ Quinidine
■ Avoid:
■ AV-nodal blocking drugs if accessory pathway suspected
■ Chemical or elective electrical cardioversion in chronic atrial fibrilla-
tion until after3–4 weeks of systemic anticoagulationCOMPLICATIONS
■ Cardiovascular collapse: If accessory pathway and AV-nodal blocking agents
given
■ Embolic stroke
■ >24 hours of symptoms associated with higher risk of intra-atrial clot
and possible resultant stroke
■ The risk of embolus and risk-based treatment for patients with chronic/
recurrent atrial fibrillation is summarized in Table 1.7.AV-NODALREENTRANTTACHYCARDIA(AVNRT)AVNRT is the most common cause of paroxysmal SVT and results from the
formation of a “circus reentrant” pathway within the AV node. It is usually
clinically stable.PATHOPHYSIOLOGY
■ Requires presence of two limbswithin the AV node with different refractory
times
■ PAC arrives when only one limb is fully recovered →impulse travels down
this limb to distal AV node →refractory second limb is now recovered →
impulse travel retrograde up this limb →reentry circuit now established.RESUSCITATION
FIGURE 1.11. Atrial fibrillation.
AV-nodal blocking drugs
should be avoided in AFib or
a-flutter if an accessory
pathway is suspected.