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Cardioanaesthesia

Cardioanaesthesia. Coronary artery disease. O 2 delivery Coronary blood flow = directly related to coronary perfusion pressure (CPP) CPP = aortic diastolic pressure – LVEDP = inversely related to HR = inversely related to coronary vascular resistance Blood viscosity Sympathetic tone

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Cardioanaesthesia

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  1. Cardioanaesthesia

  2. Coronary artery disease O2 delivery Coronary blood flow = directly related to coronary perfusion pressure (CPP) CPP = aortic diastolic pressure – LVEDP= inversely related to HR= inversely related to coronary vascular resistance • Blood viscosity • Sympathetic tone • Fixed resistance due to athermanous narrowing

  3. Coronary artery disease O2 delivery Coronary blood flow = directly related to coronary perfusion pressure (CPP) CPP = aortic diastolic pressure – LVEDP= inversely related to HR= inversely related to coronary vascular resistance • Blood viscosity • Sympathetic tone • Fixed resistance due to athermanous narrowing

  4. Anaesthesia following MI • O2 demand • HR • Systolic BP ( afterload ) • Ventricular volume ( preload ) • Myocardial contractility • Induction of ischaemia • Tachycardia & LVEDP -  demand &  supply • Hypertension -  demand,  CPP,  supply

  5. Multifactorial index of cardiac risk by Goldman • Time since MI / risk of recurrent MI or cardiac death < 3/12 30 % 3-6/12 15% 6/12 5 % • Heart failure • Dysrhythmia • Age > 70 years • Emergency procedure • Severe aortic stenosis • Poor general condition • Intraperitoneal or intrathoracic procedure

  6. Further important factors • Operation length • Hypertension • Intraoperative hypotension and hypertension

  7. Anaesthetic Management • O2 supply • NO hypoxia, anaemia, hypotension • Obstruction due to ahteroma unrelieved by vasodilators •  O2 requirement • NO sympathetic activity &  LVEDV ( preload – GTN) • Hr & BP =  20% of awake values

  8. Monitoring • Pulse • BP • ECG • II lead to detects inferior ischaemia • V5 lead to detects anterior ischaemia • CVP/ PAWP – in selected case • Rate Pressure Product (RPP) = HR x Sys.BPmaintain value < 12 000

  9. Pharmacological manipulations •  BP lighten anaesthesia; give fluids; inotrope or vasopressor •  BP deepen anaesthesia; vasodilator ( arteriolar) •  HR deepen anaesthesia; beta-blocker •  CVP/PAWP vasodilator (venous); restrict fluid; diuretic; inotrope agent

  10. Mitral Stenosis • AF • Systemic embolus • Haemoptysis -  PVP & pulmonary hypertension • C Left Atrial Pressure – pulmonary oedema •  pulmonary compliance

  11. Anaesthetic considerations • Fixed CO – SVR must be maintainedBP = HR x SVR • Ventricular filling depends on high Atrial Pressure •  HR – reduced diastolic time for ventricular filling &  CO • Hypoxia -  pulmonary vascular resistance

  12. Mitral regurgitation • Left ventricular dilatation & hypertrophy •  LV Stroke volume + LA fluid overload • In chronic case: dilation of the atrium limits pressure rise • In acute case : PCWP is high + severe pulmonary oedema

  13. Anaesthetic considerations • Fraction of blood regurgitating • Size of MV orifice during systole • HR (slow = more regurgitation) • Pressure gradient across the valve • Relative resistance of flow ( low SVR favours flow to aorta) • Mild  HR,  SVR • NO excessive myocardial depression • Antibiotic prophylaxis

  14. Aortic stenosis • Angina -  O2 demand (muscle mass, wall tension),  supply ( diastolic pressure,  LVEDP) • Left ventricular hypertrophy • Reduction AV area by 25 % results in symptoms • Gradient of 50 mm Hg = significant stenosis

  15. Anaesthetic considerations • Thick ventricle = reduced compliance • Atrial contraction is important for optimal ventricular filing – SINUS RYTHM • Higher PAWP to maintain CO • NO tachycardia • less time for ejection & filling • Likelihood ischaemia • Fixed CO so SVR must not be reduced to maintain BP;high SVR – high LVP – ischaemia • Coronary blood flow depends on aortic diastolic pressure

  16. Aortic regurgitation • Left ventricular hypertrophy • Magnitude of regurgitation depends on: • HR – longer diastole grater regurgitation • Diastolic aortic pressure • Size of orifice during diastole • Ischaemia is not a prominent finding (pressure work is low)

  17. Anaesthetic considerations • Slight tachycardia •  SVR • Antibiotic prophylaxis

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