The current approach to the atrial fibrillation patient with a rapid ventricular response who is very hypotensive, of course, is to cardiovert, but this rarely works, especially if the patient is chronically in AF. Instead these techniques may give a better outcome.
- Use maximum energy on the first attempt — this will not cause more cardiac injury than the use of fewer joules — and position the pads optimally. Use AP pad placement (R parasternal and L tip of scapula), which has been shown in some studies to have a higher success rate than typical anterolateral placement.
- The coronary arteries fill during diastole. Raising the diastolic blood pressure >60 mm Hg improves blood flow to the coronary arteries and makes the myocardium less irritable. Use push-dose phenylephrine, 50-200 mcg q 1-2 min PRN, to raise the diastolic blood pressure >60 mm Hg. This will temporize the situation and make the patient's heart more likely to slow down. Phenylephrine is not a chronotrope and adds some vagal tone, which may help with the heart rate.
- Magnesium? No. Recent literature indicates that it is of no benefit.
- Work on rate control now that the blood pressure is a bit higher. Use amiodarone 150 mg slowly to reduce the risk of hypotension. Alternatives are diltiazem and beta-blockers (esmolol). Again, go low and slow: 2.5 mg/min aliquots of diltiazem, for example.
- Now return to the underlying problem of AF. Increase your chances of synchronized cardioversion with pharmacological enhancement. Several agents can be used, but ibutilide has the most supportive data. Pretreating a patient with ibutilide (0.01 mg/kg over 10 minutes, waiting 10 minutes, and then cardioverting) significantly increases the chance of successful cardioversion and the duration of time the patient remains in sinus after cardioversion. (Sources: Heart 1999;82:726; Circ Arrhythm Electrophysiol 2016;9, doi: 10.1161/CIRCEP.116.004521; Circulation 2014;130:2071; J Cardiovasc Med 2006;7:124.)
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