Transcript No Slide Title

Amiodarone Use in Cardiac
Surgical Resuscitation
Jeffrey R. Balser, M.D., Ph.D.
Associate Professor, Anesthesiology and Pharmacology
Associate Dean, Physician Scientist Development
Vanderbilt University School of Medicine
Nashville, TN 37232
Ventricular Arrhythmias
Arrhythmia
• PVCs, nonsustained VT
Common Substrates
normal ventricle, periop
• Sustained monomorphic VT
prior MI, structural disease
• Polymorphic VT with normal QT
Ventricular fibrillation
acute ischemia, infarction,
idiopathic cardiomyopathy
• Polymorphic VT with
prolonged QT interval
(torsade de pointes)
congenital, prior drugs,
low K, Mg, bradycardia
Most common sustained VT/VF in
cardiac surgery
• Normal QT Polymorphic VT
(ischemia, hypothermia, infarction,)
• Ventricular Fibrillation (VF)
- Little data on pharmacologic therapy for VT/VF in
surgical patients… however, there are recent data in
nonsurgical patients
IV Amiodarone in ICU patients
• Recurrent VT/VF refractory to lidocaine,
procainamide, and bretylium:
– 40% arrhythmia-free at 24 hrs
JACC 27:67, 1996
• After lidocaine and procainamide failure
– efficacy: bretylium = amiodarone
– side effects: bretylium > amiodarone
Hypotension: 33% vs. 21%
CHF: 5% vs. 0%
Circ 92:3255, 1995
IV Amiodarone in Cardiac Arrest
504 victims of out-of-hospital cardiac arrest in Seattle
• IV amiodarone (300 mg) or vehicle control
administered by emergency personnel following
3 defibrillation attempts and 1 mg of epinephrine
while CPR continued.
• The likelihood of being resuscitated and being
admitted to the hospital was 44% in the treatment
group vs. 34% in the placebo arm (p = 0.03)
Kudenchuk et al., N Engl J Med. 1999;341:871-8
Recent Recommendations for VT/VF
Management in Cardiac Arrest
Airway, Breathing, etc..
Defibrillatory Shocks
If refractory: consider antiarrhythmic drugs
amiodarone (IIb), lidocaine (Indeterminate),
magnesium (IIb if hypomagnesemic state)
procainamide (IIb for intermittent/recurrent VF/VT)
Circulation 2000 (Aug 22), 102:I-147
Evidence-based recommendations:
Terminology
IIb (Amiodarone, Procainamide)
• Consensus review of evidence by experts in the field
suggest the intervention is “Fair to Good”
• Considered within “standard of care”: reasonably
prudent physicians can use.
• Considered optional or alternative interventions by
majority of experts (versus an intervention of choice
for IIa recommendation)
Circulation 2000 (Aug 22), 102:I-147
Evidence-based Recommendations:
shock-refractory VT/VF
Lidocaine: new recommendation is “Indeterminate”
Lidocaine has not been shown to be
effective in treating human cardiac
arrest during shock-resistant VF
Circulation 2000 (Aug 22), 102:I-149
Unique Features of IV Amiodarone
• No known value to combine with other agents
- usually discontinue lidocaine, procainamide,
and other antiarrhythmic agents when using IV
amiodarone
• Loading is empiric
- 150 mg IV (rate as hemodynamically tolerated)
- 2-4 loading doses are often needed
- more are not unheard of….
IV Amio in Electrical Storm
Typical Scenario
VF! (CPR)
Shocks
VF recurs
(10 sec)
load IV amio
(150 mg/5-10 min)
Shock VF
sinus rhythm
(30 sec)
6 hrs:  amio
sinus
to 0.5 mg/min
rhythm
VF recurs
sinus rhythm (for now)...
reload IV amio
shock VF
reload IV amio (no agent change)!
1 min later:
VF recurs
start amio infusion:
1 mg/min (6 hrs)
Shock VF
sinus rhythm
lasting 5-10 min
Features of IV Amiodarone Use
• Rarely chemically converts VF -maintains SR after defibrillatory shocks
- load, shock, SR, VF, load, shock, SR….
Sign of drug “response” may be gradual
lengthening of the interval of SR between
episodes of VF
• Amiodarone and its solvent are both vasodilators
- pressors may be needed to support BP during
amiodarone loading (especially in SR)
Summary: VT/VF Pharmacologic
Strategies in Cardiac Surgery
• Nonsustained VT: Usually does not require drug therapy
• Sustained VT/VF:
- Drug-induced Long QT, Torsades de Pointes:
Defibrillation, then K+, Mg2+, pacing
- Other VT/VF: No controlled trials in surgical patients
- data in other settings (ICU, out-of-hospital)
support the use of IV amiodarone in preference
to lidocaine