EFFECT OF ANAESTHETIC AGENTS ON CARDIOVASCULAR SYSTEM. www.anaesthesia.co.in [email protected] CARDIOVASCULAR SYSTEM. Cardiac output (Stroke volume x Heart rate) Systemic vascular resistance (B.P. / C.O.) Coronary blood flow & autoregulation Arrhythmogenicity.
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EFFECT OF ANAESTHETIC AGENTS ON CARDIOVASCULAR SYSTEM
Direct myocardial depressant C.O.
sympathetic N.S. activity peripheral vasoconstriction
Minm change in BP
influx of Ca++ through slow channels
binding of Ca++ by plasma membrane
uptake & release of Ca++ by SR
by halothane BP, SV, RAP due to alterations in Ca++ metabolism
Direct effect on SAN
Sensitizes heart to Epi
automaticity of SAN
Slows myocardial conduction
Coronary steal phenomenon
Coronary stenosis + coronary perfusion pressure Detrimental redistribution of coronary blood flow with Isoflurane Contractile dysfunction; more in region distal to a critical coronary stenosis Avoided if CPP restored
Cardiovascular side effects
Potency : Sufent > Fent > Morph > Peth
C.V. S/Es : Peth > Morph > Fent > Sufent
Not reduced by slower injection
Dose – related
Additive over time in case of divided doses
Seen with d-TC, Pan, Roc
Reduced by slower injection rate
Can be prevented by A/Bs, NSAIDs
Lignocaine > Etidocaine > Bupivacaine
Recovery of Na+ channels from lignocaine is complete, even at high HRs
Depresses rapid phase of depolarization more
Rate of recovery from use-dependent block slower
Incomplete restoration of Na+ channels available between action potentials, esp at high HRs
Anti - arrhythmic
Bupivacaine : R- bupi more cardiotoxic.
Prolonged PR-interval & QRS complex, predisposition to re-entrant arrhythmias, VT / VF / Heart blocks / CHF (due to loss of contractility) resistant to defibrillation
* To surgery
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