Anaesthesia and ihd

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Anaesthesia and IHD

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Anaesthesia and ihd

  1. 1. Welcome TOWeekly SCIENTIFIC Seminar ORGANIZED BY DEPARTMENT OF ANAESTHESIOLOGY SBMCH,BARISAL
  2. 2. Anaesthesia for Noncardiac surgery in patient with IHD DR. MIZANUR RAHMAN Anaesthesiologist Department of Anaesthesia Sher-E-Bangla Medical College Hospital, Barisal
  3. 3. Overview Leading cause of death & health care expenditure5% of patients over 35 years of age have asymptomatic ischaemic heart diseaseMajor cause of morbidity & loss of productivity May be present in up to 30% of older pts undergoing surgeryCardiac dysrhythmias[VF] are the major cause of sudden death.
  4. 4. Risk Factors for Development of Ischemic Heart Disease Male gender Increasing age Hypercholesterolemia Hypertension Cigarette smoking Diabetes mellitus Obesity Sedentary lifestyle Genetic factors Family history of premature ischemic heart disease (male <55 yrs of age, female <65 yrs)
  5. 5. Risk Factors for Development of Ischemic Heart Disease Male gender Increasing age Hypercholesterolemia Hypertension Cigarette smoking Diabetes mellitus Obesity Sedentary lifestyle Genetic factors Family history of premature ischemic heart disease (male <55 yrs of age, female <65 yrs)
  6. 6. Risk Factors for Development of Ischemic Heart Disease Male gender Increasing age Hypercholesterolemia Hypertension Cigarette smoking Diabetes mellitus Obesity Sedentary lifestyle Genetic factors Family history of premature ischemic heart disease (male <55 yrs of age, female <65 yrs)
  7. 7. Risk Factors for Development of Ischemic Heart Disease Male gender Increasing age Hypercholesterolemia Hypertension Cigarette smoking Diabetes mellitus Obesity Sedentary lifestyle Genetic factors Family history of premature ischemic heart disease (male <55 yrs of age, female <65 yrs)
  8. 8. Risk Factors for Development of Ischemic Heart Disease Male gender Increasing age Hypercholesterolemia Hypertension Cigarette smoking Diabetes mellitus Obesity Sedentary lifestyle Genetic factors Family history of premature ischemic heart disease (male <55 yrs of age, female <65 yrs)
  9. 9. . Patients with ischemic heart disease can present with chronic stable angina or with acute coronary syndrome. The latter includes ST elevation myocardial infarction (STEMI) on presentation and unstable angina/non–ST elevation myocardial infarction (UA/NSTEMI)
  10. 10. Screening & Evaluation History: Symptoms such as angina and dyspnoea may be absent at rest Emphasizing the importance of evaluating the patients response to various physical activities such as walking or climbing stairs Limited exercise tolerance in the absence of significant lung disease is very good evidence of decreased cardiac reserve. If a patient can climb two to three flights of stairs without symptoms, it is likely that cardiac reserve is adequate. Silent Myocardial Ischemia Previous Myocardial Infarction Co-Existing Noncardiac Diseases Current Medications
  11. 11. Physical examination Signs of right and left ventricular dysfunction must be sought. A carotid bruit may indicate cerebrovascular disease. Orthostatic hypotension may reflect attenuated autonomic nervous system activity due to treatment with antihypertensive drugs. Jugular venous distention and peripheral edema are signs of right ventricular failure. Auscultation of the chest may reveal evidence of left ventricular dysfunction such as an S3 gallop or rales. Family history ➣
  12. 12. Clinical Predictors of IncreasedPerioperative Cardiovascular Risk
  13. 13. An algorithm for preoperative assessment of patients with ischemic heart disease
  14. 14. Special cardiac Investigation12-lead ECG:➣ May not show any abnormalities at rest or w/ no symptoms, or may show evidence of old MI (Q waves in 2 or more leads & >1/3 of the QRS complex length)➣ May reveal ST segment depression >1 mm from baseline w/ angina pectoris or ST- segment elevation w/ AMI or variant angina➣ Other changes with symptoms of angina pectoris: reversible T-wave inversion➣ Other findings with AMI: increased T-wave amplitude, followed by ST elevation, followed by Q-wave development & resolution of ST elevation
  15. 15. Echocardiography Can be used to assess global cardiac function. It can also be used to assess regional wall motion abnormalities & detect the presence of previous myocardial injury. LV function assessment is a major determinant of long- term prognosis. It is also used to diagnose LV thrombus in case of apical & anterior wall MI
  16. 16. Exercise electrocardiography It is less accurate than imaging studies to establish diagnosis of IHD but can give an idea about LV function & prognosis. It may not be feasible in patients with severe PVD, limited exercise tolerance, paced rhythm, abnormal ST segment or aortic stenosis.
  17. 17. Stress echocardiography This is used with pharmacologic induction of cardiac stress (dobutamine) or exercise to look at LV segmental wall function at rest & with stress. This can be also used to differentiate between viable (hibernating, stunned) & nonviable (infarcted) myocardial segments. Echocardiography at rest can be used to assess LV function, which is an important prognostic variable.
  18. 18. .Nuclear stress imaging: is used to assess coronary perfusion at rest & after stress. Nuclear tracers (technetium, thallium) are used to measure coronary blood flow. Positron emission tomography: May be used to demonstrate regional myocardial blood flow & metabolism, & hence viability.
  19. 19. Coronary angiogramCoronary angiography : Provides information about the coronary anatomy & the extent & location of the lesions. It is indicated in pts w/ unstable angina despite maximal therapy. It can provide a road map to coronary revascularization & the feasibility of percutaneous angioplasty or surgical treatment depending on the characteristics & location of the lesions. Cardiac enzyme elevation: Troponin is more specific than CK-MB ; increases within 4 hours after AMI & remains elevated up to 1 wk.
  20. 20. Preoperative preparation AHA Guideline Update on Perioperative Cardiovascular Evaluation for Noncardiac Surgery can be used for risk stratification of patients with IHD
  21. 21. Risk stratification➣ Variables related to 4 major categories: Nature of surgery (high, moderate or low risk), Presence of IHD, Presence of CHF Presence of cerebrovascular disease➣ Presence of comorbid conditions(diabetes mellitus, aortic stenosis, PVD)➣ Exercise tolerance➣ Studies may be ordered if disease severity has not been assessed previously.
  22. 22. Goldmans index of cardiac risk in noncardiac procedures
  23. 23. . History & physical exam to assess extent of disease, exercise tolerance & symptom pattern, in addition to history of comorbid diseases. Elective surgery in pts with a history of AMI should be delayed up to 6months after the episode of AMI if possible. Intraoperative tachycardia can increase the risk of intraoperative ischemia & perioperative MI. Silent myocardial ischemia may be seen as only ECG changes with no history of symptoms. Almost 70–75% of ischemic episodes in IHD pts are silent, as well as 10–15% of AMIs.
  24. 24. .■ Continue beta blockers; they were found to increase long-term survival in patients with IHD.■ Calcium channel blockers do not increase the negative inotropic & vasodilatory effects of inhalational agents but may potentiate the effects of depolarizing & nondepolarizing muscle relaxants.■ Stop ACE inhibitors the night before surgery to avoid severe hypotension intraoperatively.■ Stop aspirin 1 wk before surgery if possible; anticoagulation must be held to decrease risk of bleeding.
  25. 25. .■ Patients with coronary stents should have their surgery delayed at least 4 wks after stenting when possible.■ Lifestyle modification may affect exercise tolerance (smoking cessation, diet).■ Cholesterol & triglyceride levels should be kept within acceptable range.■ Preop studies (ECG, chest x-ray, echocardiogram, etc.) may be indicated depending on risk stratification, IHD severity & disease progression
  26. 26. Preoperative MedicationGoal-Minimizing the sympathetic system effects on the myocardium helps decrease the possibility of ischemic events perioperatively. This can be achieved by: ➣ Anxiolysis with sedatives/narcotics (benzodiazepines, opioids, scopolamine 0.4–0.6 mg IM or 0.2–0.4 mg IV) ➣ Continuation or administration of beta blockers Administration of nitroglycerine Maintain heart rate & blood pressure within 20% of normal values.
  27. 27. PreoxygenationAim –Replacement of air in Holding anaesthesia mask onFRC[20-30ml/kg] with the faceenriched O2O2 -15 L/min for 3 min
  28. 28. Anesthesia■ Induction : ➣ The main goal during induction is to avoid hypertension & tachycardia, thereby decreasing drastic cardiac events. ➣ Minimize extreme variation in heart rate & blood pressure.
  29. 29. . Control cardiovascular response to tracheal intubation by keeping low duration of laryngoscopy(<15sec) or by pharmacologic means. Pharmacologic interventions include lidocaine IV 1.5 to 2 min before intubation (1.5–2 mg/kg), intratracheal lidocaine (2 mg/kg) at the time of laryngoscopy, IV fentanyl 13 micrograms/kg, IV esmolol or IV nitroprusside
  30. 30. Nitroglycerin➣ Continuous nitroglycerine infusion was not found to decrease the incidence of intraoperative myocardial ischemia.➣ Avoid induction agents capable of stimulating sympathetic nervous system (ketamine, pancuronium)
  31. 31. Regional Anesthesia Regional anesthesia may be preferred to general anesthesia if possible, as it tends to better block the stress response to surgery. Hypotension associated with some regional techniques should be corrected by fluids & sympathomimetic agents Potential benefits of a regional anesthetic include excellent pain control, a decreased incidence of deep vein thrombosis in some patients, and the opportunity to continue the block into the postoperative period. However, the incidence of postoperative cardiac morbidity and mortality does not appear to be significantly different between general and regional anesthesia.
  32. 32. Maintenance of Anaesthesia➣ Volatile anesthetics (isoflurane, desflurane & sevoflurane) are safe to use with IHD, provided severe CHF is not present.➣ Alternative technique may be high-dose narcotic agent with oxygen & nitrous oxide.
  33. 33. Maintenance of Anaesthesia Vecuronium, rocuronium, cisatracurium are attractive choices for patients with ischemic heart disease Avoid pancuronium to reduce sympathomimetic activity. Increased sensitivity to muscle relaxants may be seen in pts on calcium channel blockers. Keep BP & heart rate within 20% of awake values. Intraoperative ischemia may be treated with beta blockers (esmolol) in case of tachycardia, IV nitrates in the case of hypertension, or IV sympathomimetics & fluids with hypotension. Maintain intraoperative heart rate at less than 80 bpm.
  34. 34. Maintenance of Anaesthesia➣ Minimizing body heat loss is vital . Body warming blanket to avoid postop shivering & precipitation of ischemic myocardial events. This can be achieved with warm IV fluids, warm operating room atmosphere, forced warm air covers & irrigation of the surgical site with warm fluids.➣ To maintain adequate myocardial oxygen delivery, do not allow hemoglobin to drop below 10 g/dL
  35. 35. Monitoring An important goal when selecting monitors for patients with ischemic heart disease is to select those that allow early detection of myocardial ischemia Most myocardial ischemia occurs in the absence of hemodynamic alterations So one should be cautious when endorsing routine use of expensive or complex monitors to detect myocardial ischemia.
  36. 36. Monitors used depend on disease severity & operative procedure complexity➣ ECG: simplest & most commonly used. ST-segment changes are principally used to diagnose myocardial ischaemia.➣ Pulmonary artery catheter: ischemia manifests as a sudden increase in PCWP, in addition to new V waves in case of new onset of ischemic mitral valve regurgitation.➣ Central venous pressure may correlate with PCWP if EF = 0.5 & there is no evidence of LV dysfunction.➣ Transesophageal echocardiography: most sensitive to detect intraoperative myocardial ischemia by detecting new onset of regional wall motion abnormality
  37. 37. Wake up and Emergence■ Proper pain control is key to avoid myocardial ischemic events.■ Muscle relaxants can be reversed with neostigmine in combination with glycopyrrolate, as the latter produces less tachycardia. Nevertheless, atropine can be used with no adverse effects as long as the pt is adequately beta blocked.■ Continuous ECG monitoring w/ ST- segment analysis is important to detect any myocardial ischemic events.■ Supplemental oxygen to maintain adequate oxygen saturation is important.■ Adequate heart rate & BP control as intraoperatively■ Treat tachycardia or hemodynamic instability.■ Avoid & treat shivering.
  38. 38. Wake up and Emergence Early extubation is possible and desirable in many patients as long as they fulfill the criteria for extubation. However, patients with ischemic heart disease can become ischemic during emergence from anesthesia and/or weaning with an increased heart rate and blood pressure. These hemodynamic alterations must be managed diligently. Pharmacologic therapy with a β- blocker or combined α- and β- blockers such as labetalol can be very helpful.
  39. 39. Intraoperative Events That Influence the Balance Between Myocardial Oxygen Delivery and RequirementsDecreased Oxygen Delivery Decreased coronary blood flow Tachycardia Diastolic hypotension Hypocapnia (coronary artery [Pulse oxymeter] vasoconstriction) Increased Oxygen Requirements Coronary artery spasm  Sympathetic nervous Decreased oxygen content system stimulation Anemia  Tachycardia Arterial hypoxemia  Hypertension Shift of the oxyhaemoglobin  Increased myocardial dissociation curve to the left contractility  Increased afterload  Increased preload
  40. 40. PERIOPERATIVE MYOCARDIAL INFARCTION 500,000 to 900,000 perioperative MIs occur annually worldwide. The incidence of perioperative cardiac injury is a cumulative result of preoperative medical condition, the specific surgical procedure, expertise of the surgeon, the diagnostic criteria used to define MI, and the overall medical care at a particular institution. The risk of perioperative death due to cardiac causes is less than 1% for patients who do not have ischemic heart disease as evidenced by a history of angina pectoris, electrocardiographic signs of MI, or angiographically documented coronary artery disease. The incidence of perioperative MI in patients who undergo elective high-risk vascular surgery is between 5% and 15%. The risk is even higher for emergency surgery. Patients who undergo urgent hip surgery have an incidence of perioperative MI of 5% to 7%, whereas less than 3% of patients who undergo elective total knee or hip arthroplasty have a perioperative MI.
  41. 41. Predictors of postoperative myocardial ischaemiaLeft ventricular hypertrophyHistory of hypertensionDiabetes mellitusKnown ischaemic heart diseaseUse of digoxin
  42. 42. Factors that can contribute toperioperative myocardial infarction
  43. 43. Diagnosis of Perioperative Myocardial Infarction The diagnosis of acute MI traditionally requires the presence of at least two of the following three elements: (1) ischemic chest pain (2) evolutionary changes on the ECG (3) increase and decrease in cardiac biomarker levels. In the perioperative period, ischemic episodes are often silent, that is, not associated with chest pain. Many postoperative ECGs are nondiagnostic. Nonspecific ECG changes, new-onset dysrhythmias, and noncardiac-related hemodynamic instability can further obscure the clinical picture of acute coronary syndrome in the perioperative period
  44. 44. PACU or ICUThe goals ofpostoperativemanagement areprevent ischemia,monitor formyocardial injury, andtreat myocardialischemia/infarction
  45. 45. Contd■ Supplemental oxygen is crucial.■ Pain control to avoid excessive sympathetic nervous system stimulation■ Maintain adequate beta blockade.■ 12-lead ECG as a baseline■ Prevention of shivering & maintenance of normothermia is crucial to avoid oxygen desaturation & sympathetic nervous system activation.■ Maintaining adequate oxygenation & tight pain control for 48 to 72 hr postop is very important, since this is the period when the likelihood of developing AMI is highest.
  46. 46. Contd It is of interest that postoperative myocardial reinfarction often occurs 48-72 hours postoperatively, a period that could correspond to discontinuation of supplemental oxygen and less aggressive treatment of pain Reasonable control of blood glucose: keep blood glucose levels 100–180 mg/dL
  47. 47. .Thank you all for watching the presentation

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