Medical Pharmacology Chapter 43:  Adult Cardiac Procedures

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Coronary Artery Disease and Anesthesia Management

Coronary Pressure-Flow Relationships


  • *Coronary Pressure Flow relationships: Y axis= Flow (ml/min); X axis =mean pressure (mm Hg)

  • Figure legend information:

    • A= autoregulation

    • D =maximal vasodilation

    • R1 and R2  : coronary flow reserves at mean coronary perfusion pressure of 75 and 100 mm Hg -- with constant aortic pressure and heart rate

  •  With coronary stenosis: Coronary vascular reserve is used to counter stenotic flow effect  

  •   Increasing coronary stenoses, associated with advancing coronary vascular disease, may use ultimately all vasodilator reserve.  In this case coronary autoregulation is used to maintain the myocardial resting blood flow

    •  When this condition occurs, cornered blood flow will vary directly with blood pressure and therefore reduced blood pressure directly reduces coronary flow and causes myocardial ischemia

    • Therefore: anesthesia major goal = In patients with significant coronary atherosclerosis: maintain arterial pressure

  • * adapted from Figure 68-1, Ross, AF, Gomez, MN. and Tinker, JH Anesthesia for Adult Cardiac Procedures in  Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., p. 1665, 1998.



  Hemodynamics and Coronary Artery Disease

Hemodynamic event

Pharmacological intervention

  • Surgical stress induces:

    • Autonomic, sympathetic stimulation which increases myocardial oxygen demand by both positive chronotropic (increased heart rate) and positive inotropic (increased contractility)

    • Increased circulating catecholamines and direct cardiac stimulation by norepinephrine release from sympathetic endings

  • Properly chosen anesthetic agents block the stress response; β-adrenergic receptor blockers also only used to avoid increased contractility/rate

  • Ventricular dilatation associated with congestive heart failure, with increasing ventricular wall stress and LVEDP (left ventricular end diastolic pressure)

  • With  left ventricular heart failure, inotropic support may improve the relationship between oxygen supply and demand

  • Increased BP increases oxygen demand and coronary blood flow; decreased BP may promote reduced coronary flow

  • Optimize coronary flow by maintaining blood-pressure at  or slightly above normal (may require α-adrenoceptor agonist administration)

  • Tachycardia shortens available time between heart beats for diastolic coronary blood flow.

  • prevent increased heart rate using anesthetic agents initially and β-receptor blockade as needed

  •  Increased ventricular filling pressures reduce coronary blood flow, particularly subendocardial flow.

  • Maintain reduced filling pressures using nitroglycerin

  • Provide optimal oxygenation

  • Important considerations:

    • Adequate title volume

    • Positive end expiratory pressure (PEEP)

    • Insure high inspired oxygen

    • Treat anemia with blood transfusion


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