Transcript Beta Blockers In Anesthesia

Beta Blockers In Anesthesia
Introduction
Sir James Black
Sir James Whyte Black, OM, FRS, FRSE, FRCP (born 14 July
1924) is a Scottish doctor and pharmacologist who invented
Propranolol, synthesized Cimetidine and was awarded the Nobel
Prize for Medicine in 1988 for these discoveries.
Pharmacology Of Beta
Blockers
Pharmacology of beta blockers
Sympatholytic drugs
On the heart:
heart rate,
contractility,
conduction velocity,
relaxation rate.
Pharmacology of beta blockers (cont.)
On the vessels:
Dominant
alphaadrenoceptor mediated
vasoconstrictor
influence.
Pharmacology of commonly used or novel beta blockers
Pharmacology of beta blockers (cont.)
Therapeutic
Indications
Contraindications for BB
Absolute
– Asthma
– Sick Sinus Syndrome
– Severe peripheral vascular disease
– Second or third degree heart block
Relative
– COPD
– Raynaud phenomenon
– Bradycardia
– Hypoglycemia-prone diabetics in whom the
early and warning symptoms of hypoglycemia
may be masked.
Beta blockers in non-cardiac
surgery
Beta blockers in non-cardiac surgery
 Non-cardiac surgery is associated with
an increase in catecholamines, which
results in : an increase in blood
pressure, heart rate free fatty acid
concentrations.
 Beta blockers suppress the effects of
increased catecholamines and as a
result may prevent perioperative
cardiovascular events.
Noncardiac Surgery-Evidence
Mangano Study (NEJM 1996;335:1713)
– 200 high-risk patients in a RCT DB of atenolol
IV peri-op and orally post-op ( 2 days prior
and 7 days after)
– Long-term follow-up for 2 years
– Excluded those who did not survive hospital
stay
– Reduction in overall and cardiac-related
deaths at 6 mo, 1 year and 2 years in the
atenolol group.
Noncardiac Surgery-Evidence
Poldermans Study (NEJM 1999)
– High risk patients with positive dobutamine
echocardiograms (n=111)
– Randomized to placebo or bisoprolol
– Cardiac deaths were reduced from 17% to
3.4%
– Nonfatal MI occurred in 17% of placebo group
compared to 0% in bisoprolol group
ACC 2006 Guidelines
• Class I : pre-op BB used for angina or
hypertension should be continued.
• Class I : High cardiac risk patients undergoing
vascular surgery should have BB.
• Class IIa : if preop assessment reveals
untreated hypertension, known CAD, or major
risk factors for CAD.
• Class IIb : if preop assessment reveals
patients undergoing vascular surgery with low
or intermediate cardiac risk.
• Class III – Contraindication to BB
Beta blockers in non-cardiac surgery(cont.)
Care should be taken in applying
recommendations on beta-blocker
therapy
to
patients
with
decompensated
heart
failure,
nonischemic cardiomyopathy, or
severe valvular heart disease in the
absence of coronary heart disease.
Beta blockers in non-cardiac surgery(cont.)
The Best Protocol To Initiate
Perioperative Β-blockade?
• Started a week before surgery
• Titrated to heart rate-decreasing
effect
• Use shorter acting BB to facilitate
adjustment
Beta blockers in non-cardiac surgery(cont.)
POISE
Perioperative Ischemic Evaluation (POISE)
trial, a randomized controlled trial of
metoprolol versus placebo in 10,000
patients undergoing noncardiac surgery.
Beta blockers in cardiac
surgery
Beta blockers in cardiac surgery
• 10% of cost of cardiac surgery is for
treatment of complications = 1 billion $ in US
annually BB reduce post-op atrial fibrillation
(AFIB) which is associated with > LOS > cost
($10,000), and > risk of stroke.
• Withdrawal of BB in the peri-operative period
doubles the risk of AF
• Mainly studied as a post-operative therapy to
prevent AF
Beta blockers in cardiac surgery(cont.)
 ESC/ACC/AHA Guidelines :
• Beta blockers as a first-line medication for
prevention of AF after CABG in patients
without contraindications.
• In patients undergoing cardiac surgery on
pre-existing
beta-blocker
therapy,
this
treatment should be continued unless
contraindications develop
Beta blockers in cardiac surgery(cont.)
 NICE Guidelines on AF management postoperativly should be reduced by:
• Amiodarone
• Beta-blocker Sotalol or
• Ratelimiting calcium antagonists
Beta blockers in cardiac surgery(cont.)
Sotalol
 Class II and III antiarrhythmic effects.
 Lower frequency of postoperative AF.
 Combination therapy
 Titrated carefully with regular QT interval
monitoring.
 Caution in renal insufficiency.
Beta blockers in cardiac surgery(cont.)
Esmolol
 Cardioselective beta1 blocker.
 Ultra-short–acting(10 minutes).
 Uses:
• Perioperative control of blood pressure.
• Control of arrhythmias.
Beta blockers in cardiac surgery(cont.)
Esmolol
 Recently used to induce “minimal myocardial
contraction”
 It gives myocardial protection equivalent to
cardioplegia.
 Scorsin et al(Thor & Cardiovas Sur2003)
• Esmolol and potassium
• Continuous normothermic retrograde blood
cardioplegia
• markedly decreased myocardial oxygen
consumption with esmolol
Recommendations
Administrative data may be able to
provide some evidence as to baseline
rates.
Exact criteria for use need to be
clarified.
Clarification is needed as to the exact
timing of therapy and the appropriate
patient population
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