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Perioperative myocardial infarction ppt

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Perioperative myocardial infarction ppt

  1. 1. DR .Y. SASIKUMAR
  2. 2. Perioperative myocardial infarction( PMI ) is the common cause ofmorbidity and mortality in patientswho have had noncardiac surgery.
  3. 3. INCIDENCE5.8% overall risk of postoperative major cardiaccomplications in patients undergoingmajor noncardiac surgical procedures.Defining PMI, is often difficult : Most PMIs occur without symptoms in anesthetized orsedated patients. The creatine kinase-MB isoenzyme has limitedsensitivity and specificity because of coexisting skeletalmuscle injury.Consequently, PMI was often recognized late(postoperative day 3 to 5), resulting in high (30% to70%) mortality.
  4. 4. Two distinct mechanisms may lead to PMI: Acute coronary syndrome. Prolonged myocardial oxygen supply-demand imbalance in the presence of stablecoronary artery disease (CAD).
  5. 5.  Acute coronary syndrome occurs when anunstable or vulnerable plaque undergoesspontaneous rupture, fissuring, or erosion,leading to acute coronary thrombosis,ischemia, and infarction. External stressors ,those occurringpostoperatively are believed to contribute.
  6. 6.  The sympathetic induced Tachycardia andHypertension, common in the perioperativeperiod, may exert shear stress, leading to ruptureof plaques. Increased postoperative procoagulants(fibrinogen, factor VIII coagulant, von Willebrandfactor, α1-antitrypsin), increased plateletreactivity, decreased endogenous anticoagulants(protein C, antithrombin III), and decreasedfibrinolysis have been reported.
  7. 7.  Tachycardia is the most common cause ofpostoperative oxygen supply-demandimbalance. Heart rates >80 bpm in patients withsignificant CAD can lead to prolongedischemia and PMI.
  8. 8.  Postoperative hypotension(hypovolemia, bleeding, or systemicvasodilatation), hypertension (elevated stresshormones, vasoconstriction), anemia, hypoxemia, and hypercarbia aggravate ischemia. Stress-induced and ischemia-inducedcoronary vasoconstriction impairs coronaryperfusion.
  9. 9. The 2007 ACC/AHA guidelines on cardiovascularevaluation for noncardiac surgery concluded thatthree elements must be assessed to determine therisk of cardiac events : Patient specific clinical variables. Exercise capacity. Surgery-specific risk.
  10. 10. Major predictors that require intensive managementand may lead to delay in or cancellation of theoperative procedure. Unstable coronary syndromes including unstableangina or recent MI. Decompensated heart failure including NYHAfunctional class IV or worsening or new-onset HF Significant arrhythmias Valvular heart disease-severe AS/ severe MS
  11. 11. Other clinical predictors that warrant carefulassessment of current status. History of ischemic heart disease History of cerebrovascular disease History of compensated heart failure or priorheart failure Diabetes mellitus Renal insufficiency
  12. 12. The 2007 ACC/AHA guidelines on cardiovascularevaluation for noncardiac surgery concluded thatthree elements must be assessed to determine therisk of cardiac events : Patient specific clinical variables. Exercise capacity. Surgery-specific risk.
  13. 13.  Patients with good functional status have a lowerrisk of complications. Functional status can be expressed in metabolicequivalents (MET). 1 MET is defined as the oxygen uptake in a sittingposition (3.5 mL O2 uptake/kg per min). Perioperative cardiac risk is increased in patientsunable to meet a 4-MET demand during mostnormal daily activities.
  14. 14. Indicators of functional status : Can walk up a flight of steps = 4 METs Can do heavy work around the house such asscrubbing floors or lifting or moving heavyfurniture = between 4 and 10 METs Can participate in strenuous sports such asswimming, singles tennis, football, basketball= = >10 METs
  15. 15. The 2007 ACC/AHA guidelines on cardiovascularevaluation for noncardiac surgery concluded thatthree elements must be assessed to determine therisk of cardiac events : Patient specific clinical variables. Exercise capacity. Surgery-specific risk.
  16. 16. The type and timing of surgery significantlyaffects the patients risk of perioperative cardiaccomplications. High-risk procedures - Rate of cardiac deathor nonfatal MI is > 5% Intermediate-risk procedures – 1% - 5% Low-risk procedures - < 1%
  17. 17.  Institutional and/or individual surgeonexperience with the procedure may increaseor lower the risk. Emergency surgery is associated withparticularly high risk (5 times) than withelective procedures.
  18. 18.  Multivariable analyses, identified combinations offactors, based upon routine clinical informationand laboratory tests, that used to estimate the riskof cardiac complications. It was developed by Goldman, Detsky, and Eagle
  19. 19.  High-risk type of surgery ( vascular surgery andopen intraperitoneal or intrathoracic procedures) History of ischemic heart disease. History of HF. History of cerebrovascular disease. Diabetes mellitus requiring treatment with insulin. Preoperative serum creatinine >2.0 mg/dL (177µmol/L).
  20. 20. Rate of cardiac death, nonfatal myocardialinfarction, and nonfatal cardiac arrest according tothe number of predictors. No risk factors - 0.4 % One risk factor - 1.0 % Two risk factors - 2.4 % Three or more risk factors - 5.4 %
  21. 21. RECOMMENDATIONS CLASS LEVELFor patients with cardiac risk factor (s)undergoing inter meadiate or high – risksurgeryI BFor patients with cardiac risk factor (s)undergoing low - risk surgeryIIa BFor patients with no cardiac risk factorsundergoing high / intermediate risk surgeryIIb B
  22. 22. RECOMMENDATIONS CLASS LEVELFor patients with severe valvular heartdisease.I CIn patients undergoing high-risksurgery for LV assessment.IIa C
  23. 23. RECOMMENDATION CLASS LEVELFor patients with > 2 cardiac risk factorsundergoing high risk surgeryI BFor patients with < 3 cardiac risk factorsundergoing high risk surgeryIIb BFor patients undergoing intermediate risksurgeryIIb C
  24. 24. RECOMMENDATION CLASS LEVELAcute STEMI / NON-STEMI /Unstable anginaAngina unresponsive to medical treatmentI ACardiac stable patients undergoing high risk surgery IIb BCardiac stable patients undergoing intermediate risksurgeryIIb C
  25. 25.  Diagnosis complicated by lack of symptomaticpresentation in about half of patients with perioperativeMI.Deveraux et al, proposed the following diagnostic criteria:Rise in troponin (or fall after an elevated value) plus one ormore of following.Ischemic signs or symptoms (e.g., SOB)New pathologic Q waves on ECG.New wall motion abnormality or fixed defect on echo.
  26. 26. BETA BLOCKERS Beta blockers have been used in patients undergoingnoncardiac sx, in those at high risk.Possible mechanisms for such a benefit include Reduction in myocardial oxygen demand Increase in myocardial oxygen delivery due toprolongation of coronary diastolic filling time. Prevention of fatal ventricular arrhythmias, protection against plaque rupture in the setting ofincreased sympathetic activity .
  27. 27.  The large Perioperative Ischemic Evaluation (POISE)trial reported increased mortality and, mostly inassociation with hypotension in patients treatedwith metoprolol. The evidence does not support the initiation ofprophylactic perioperative beta blocker therapy inmost patients undergoing noncardiac surgery (RCRI≤2). POISE does not exclude benefit in high risk patients(RCRI ≥3)
  28. 28. If beta blockers are used Beta-1 selective agent, begin as an outpatient upto 30 days prior to operation, titrating to HR 50-60BPM. Longer-acting agent (atenolol or bisoprolol) maybe more effective than shorter-acting agent(metoprolol). Benefit was demonstrated when therapy wasbegun one month before surgery.
  29. 29. Statins Recommend in those already being treated or withother indications for treatment. There is no convincing evidence of benefit ofstarting therapy in those patients who otherwise donot meet accepted criteria for initiation of statintherapy.
  30. 30. Aspirin The accepted practice is to discontinue aspirin 5 to7 days before a surgical procedure to preventbleeding. Recent analyses suggest that there is only a mildincrease in the frequency of bleeding with aspirinand no increase in mortality. Possible exceptions are intracranial and prostatesurgery.
  31. 31.  Two recent prospective randomized trials(Coronary Artery Revascularization Prophylaxis[CARP] and Dutch Echographic Cardiac RiskEvaluation Applying Stress Echo [DECREASE] failedto show such benefit. Revascularization prior to noncardiac surgeryshould only be performed in patients who havehigh-risk coronary anatomy that fulfill currentcriteria applicable to all patients with coronarydisease.
  32. 32.  European Heart Journal (2009) British journal of Anaesthesia 107; 83-96 (2011) Up Todate 2011 (19.3) Medscape
  33. 33. Thank you

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