Tolerance of High-Dose Oral Amiodarone for Cardioversion of Atrial Flutter

Figures

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  Figure 1. (A) Two-compartment (cmpt) model of amiodarone pharmacokinetics. Most medications conforming to a 2-cmpt model have the following: a small peripheral (Periph) cmpt (considered 1-cmpt if very small); an elimination half-life (Elim T½) measured in hours; a steady state reached within days; and vascular concentrations that are highly sensitive to multiples of a normal daily dose. Amiodarone instead has the following: a very large periph cmpt; a T½ of distribution (Dist) rapid enough to promote net movement of drug out of the vascular cmpt until concentrations in periph cmpt slowly equilibrate to steady state (purple arrow); and vascular concentrations that, following any rapid change, return to near pre-bolus values by distributing drug to periph cmpts. (B) Serum concentrations of amiodarone (AMIO) during 14 months of therapy. The green line indicates AMIO; the blue line indicates desethylamiodarone (DEA) metabolite; the yellow bar indicates desirable amiodarone range for long-term maintenance; the red line indicates target threshold for local transient AMIO concentration to effect rhythm conversion; the red triangles indicate predicted 12-hour AMIO concentration post 4800-, 6000-,…

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  Figure 2. Electrocardiograms (ECGs) before and after pharmacologic cardioversion. (A) Initial ECG prior to cardioversion showing typical anticlockwise atrial flutter with 2:1 conduction, heart rate of 145 beats per minute, and rightward axis. (B) ECG post-cardioversion at presentation to the hospital showing sinus arrest with a junctional escape rhythm, heart rate of 36 beats per minute, and rightward axis.