Cardiovascular Critical Care I
| (b) | Heart rhythm control |
|---|---|
| (1) | Antiarrhythmic therapy typically with class Ic or class III agents (see Appendix A) |
| (2) | Synchronized electrical cardioversion |
| (3) | Catheter-based ablation |
| (4) | Surgical ablation |
ii.
Ventricular tachyarrhythmias
| (a) | Catheter ablation |
|---|---|
| (b) | Antiarrhythmic therapy |
| (c) | Evaluation for implantable cardioverter-defibrillator |
Overall considerations for antiarrhythmics (see Appendix A) (Circulation 2014;130:2071-104; Heart
Fail Rev 2014;19:285-93; Circulation 2012;125:381-9; BMJ 2002;324:594-7; BMJ 2002;324:776-9;
BMJ 2002;324:1264-7; BMJ 2002;324:1201-4)
Abrupt discontinuation of chronic antiarrhythmics (i.e., chronic medication before ICU
admission) should be done with caution and awareness of antiarrhythmic indication as well as
risks-benefits of continuation/cessation.
ii.
Appropriate monitoring and potential adjustment may be warranted with many of these agents
in the critically ill patient.
| (a) | QT/QTc prolongation increases the risk of Torsades de pointes. This risk can be influenced |
|---|
not only by the absolute duration of the QT/QTc but also by the rate at which the QT/QTc
is changed (i.e., faster change may also increase risk).
| (b) | The class III antiarrhythmics sotalol and dofetilide can be used for a variety of arrhythmias |
|---|
(most notably AF/AFl) and, because of some notable characteristics, should be watched
closely when used in the critically ill patient.
| (1) | Both are renally eliminated. |
|---|---|
| (2) | Both have notable interactions with several other medications (especially dofetilide |
on the basis of CYP3A4 and renal transport) in addition to their effect on the QT/QTc
interval.
| (3) | ECG, electrolytes, and renal function monitoring should be performed for safety |
|---|
and tolerability 2–3 hours after the first five doses when initiating, reinitiating, or
introducing another interacting or QT-prolonging agent.
| (4) | Electrolyte abnormalities may place a patient at increased risk of Torsades de pointes |
|---|
(particularly magnesium and potassium).
| (5) | Dofetilide is particularly useful among patients with structural heart disease |
|---|
(including HF) because of a neutral effect on mortality. In contrast, sotalol has been
associated with increased mortality in patients with HF and is not recommended in
this patient population for atrial arrhythmias.
| (c) | If a patient develops Torsades de pointes, the patient should be managed with the following: |
|---|---|
| (1) | Intravenous magnesium 2-g rapid infusion |
| (2) | Discontinuation of any offending medications contributing to QT prolongtion |
| (3) | Pharmacologic pacing with beta agonists (i.e., isoproterenol, dobutamine, epinephrine, |
dopamine); bradycardia increases the risk for TdP, so increasing HR can help prevent
future events
| (4) | Correction of electrolyte disturbances such as hypokalemia |
|---|---|
| (5) | Temporary pacing to increase heart rate |
iii.
Common agents in the ICU used to treat tachyarrhythmias
| (a) | β-Blockers |
|---|---|
| (1) | May be of limited use in patients receiving vasopressors and/or inotropes, but can be |
used for both atrial and ventricular tachyarrhythmias