Ch.20 Anesthesia for patients with cardiovascular disease

1. Ch.20 Anesthesia for patients with cardiovascular disease R1 김용일

2. Introduction • Cardiovascular disease : most frequently encountered in anesthetic practice • Already compromised cardiovascular system의 부담 • Surgical stimulation에 대한 adrenergic response • Anesthetic agents, endotracheal intubation, positive-pressure ventilation, blood loss, fluid shifts, body temperature 변화에 대한 circulatory effects • Chronically enhanced sympathetic activity의 중단으로 acute circulatory decompensation 가능 • Choice of anesthetic agent is not as important as how the agent is used and an understanding of the underlying pathophysiology

3. Cardiac risk factors

4. 흔히 마주치는 문제들 • Perioperative myocardial infarction • Pulmonary edema • Congestive heart failure • Arrhythmias • Thromboembolism • Cardiovascular complication : 25-50% of deaths following noncardiac surgery

5. Clinical predictors of increased perioperative cardiovascular risk • Mj predictor 있을 시 : Noninvasive cardiac evaluation • 가장 중요한 요소 Unstable coronary syndrome Congestive heart failure • C/I of elective op 1달 이내의 MI Uncompensated heart failure Severe aortic or mitral stenosis

6. Mx of intermediate or minor predictors

7. Cardiac risk stratificationfor non cardiac surgical procedures • 응급수술은 2-5배의 위험성 • Poorly controlled HTN은 wide intraOP BP swing을 흔히 초래 • intraOP HTN은 cardiac morbidity에 hypotension보다 관련 • Well-managed general anesthesia보다 spinal 또는 epidural anesthesia의 hemodynamic effect가 더욱 위험할 수도 있음

8. HYPERTENSION

9. Preoperative considerations • HTN : leading cause of death and disability & most frequent preOP abNL in surgical Pt • Overall prevalence : 20-25% • Mj risk factor for Cardiac, cerebral, renal and vascular disease • Cx MI, CHF, stroke, renal failure Peripheral occlusive disease, aortic dissection • LVH, carotid bruits : cardiac mortality 증가

10. Definitions • BP measurements Affected by posture, time, emotional state, recent activity, drug intake, equipment, technique • Preoperative anxiety or pain : BP 상승 초래 • Stage 3 (accelerated or severe HTN) : renal dysfunction 흔함 • Malignant HTN: >210/120 ㎜Hg with papilledema, encephalopathy

11. Pathophysiology • Idiopathic(essential) or less commonly secondary : renal dis., primary hyperaldosteronism, Cushing’s syndrome, acromegalym,pheochromocytoma, pregnancy, estrogen therapy 등 • Essential hypertension의 course of the disease • Cardiac output 증가, but, SVR appears in NL • Cardiac output 회복, but, SVR becomes high • Chronic increase in cardiac afterload는 concentric LVH, altered diastolic function 초래 • Cb autoregulation 변화로 NL Cb blood flow는 유지

12. Pathophysiology(2) • Mechanisms remain elusive but : • Vascular hypertrophy • Hyperinsulinemia • intracellular Ca 증가 • vascular smooth muscle and renal tubular cell 내의 Na 농도 증가 • Sympathetic nervous system overactivity • Overactivity of renin-angiotensin-aldosterone system : important tole in accelerated HTN

13. Long-term treatment • Drug therapy • progression of HTN 감소 • Stroke, CHF, CAD, renal damage 감소 • LVH, altered Cb autoregulation등의 회복 가능 • 대부분 single-drug therapy로 치료 가능 • Low doses of a thiazide diuretic for most patients • ACE inhibitor : Lt ventricular dysfunction or heart failuretl 1st-line choice • ACEI or ARB (angiotensin-receptor blocker) : hyperlipidemia, chr. Renal dis., DM시 optimal initial single agent • β-adrenergic blocker, calcium channel blocker : 1st-line agent for CAD • Elderly Pt. : diuretic with or without β-adrenergic blocker, or calcium channel blocker alone

14. HYPERTENSION PREOPERATIVE MANAGEMENT

15. 대부분 HTN Pt.는 어느정도 HTN을 가지고 op room에 들어옴 • Untreated or poorly controlled hypertensive Pt. • Intraoperative episodes of MI, arrhythmias, both hypertension and hypotension • 수술중 마취심도 조절 및 vasoactive drug 사용은 post-op Cx을 줄일 수 있음 • Altered Cb. Autoregulation때문에 과도한 BP 강하는 Cb. Perfusion 부족을 초래할 수 있음

16. Antihypertensive drug은 수술 직전까지 지속 • 일부에서는 intraop hypotension 우려 때문에 수술 당일 ACE inhibitor 투여를 중단하기도 함 • 이러한 경우 perioperative HTN 위험이 높아지며 parenteral antihypertensive agent 사용이 증가함 • 110 ㎜Hg이상의 sustained preoperative diastolic BP 시에는 (특히 end-organ damage 있을 경우) 수일에 걸쳐 BP control이 더 잘 될 때까지 수술 연기

17. History • Severity and duration of the HTN, drug therapy, hypertensive complication 유무 • Sx of MI, ventricular failure, impaired Cb perfusion, peripheral vascular dis. • Pt’s record of compliance with the drug regimen • Questions should concern : • Chest pains, exercise tolerance • Shortness of breath(특히 밤에) • Dependent edema, postural lightheadedness, • Syncope, amaurosis, claudication • Adverse effects of current antihypertensive drug

18. Physical examination & laboratory evaluation • Ophthalmoscopy • Visible changes in the retinal vasculature • Arteriosclerosis및 다른 장기의 hypertensive damage 정도와 진행에 비례 • Physical findings • S4 gallop : LVH • Pulm rale & S3 gallop : CHF • ASx carotid bruits • atherosclerotic vascular dis.를 반영 • Doppler에서 나타나면 hymodynamically significant blockage를 r/o 할 수 있다

19. Physical examination & laboratory evaluation(2) • BP 측정은 supine and standing position 모두에서 해야 함 • Orthostatic changes • Volume depletion • Excessive vasodilation • Sympatholytic drug therapy • 이런 경우 preoperative fluid 투여로 induction 후의 severe hypotension 막을 수 있음

20. Physical examination & laboratory evaluation(3) • ECG : 대개 정상 • Evidence of ischemia, conduction abNL, old infarction, LVH, strain • NL ECG로 CAD or LVH 가능성을 배제할 수 없음 • Echocardiography : more sensitive of LVH • CXR • Boot-shaped heart : LVH 시사 • Frank cardiomegaly • Pulmonary vascular congestion

21. Physical examination & laboratory evaluation(4) • Renal function • Serum Cr, BUN level로 평가 가능 • s-electrolyte : diuretics, digoxin 복용중이거나 renal impairment있는 환자에게 필요 • Mild to moderate hypokalemia(3-3.5mEq) : taking diuretics Pt., 대개 악영향 없음 • K replacement는 증상 있거나 digoxin 복용 중에만 • Hypomagnesemia : 수술중 부정맥의 중요 원인 • Hyperkalemia : taking K-sparing diuretics or ACE inhibitors(특히 impaired renal function시)

22. Premedication • Reduce preoperative anxiety • Mild to moderate preop. HTN • Anxiolytic agent (midazolam) • Antihypertensive agents should be continued • With a small sip of water • Central α2-adrenergic agonist (clonidine 0.2mg) • Sedation 증대 • Intraop. Anesthetic 필요량 감소 • Periop. HTN 감소 • Profound intraop. Hypotension and bradycardia 관련

23. HYPERTENSION INTRAOPERATIVE MANAGEMENT

24. Objectives • Maintain an appropriate stable BP range • Long-standing or poorly controlled HTN • Cb blood flow의 autoregulation 변화 • 적정 뇌혈류량 유지 위해 높은 BP 필요 • HTN, with tachycardia • MI, ventricular dysfunction 악화 가능 • Arterial BP는 preop level의 10-20%내 유지 • Marked HTN(>180/120 ㎜Hg) in preop. • High-NL range(150-140/90-80 ㎜Hg) 유지

25. Monitoring • Direct intraarterial pr. Monitoring • With wide swings in BP • Cardiac preload or afterload의 큰 변화가 예상되는Mj surgical procedures • ECG monitoring • Detecting signs of ischemia • Urinary output • Renal impairment있는 2시간 이상의 procedure • Invasive hemodynamic monitoring • LVEDV,CO유지 위해 PCWP12-18mmHg로 높게 유지

26. Induction • Induction, intubation : period of hemodynamic instability • 대부분 induction시 hypotension, intubation시 심한 hypertensive response 보임 • Induction시 hypotensive response는 anesthetic agents와 antihypertensive agents의 additive circulatory depressant effets에 의함(vasodilator & cardiac depressants 역할) • 대개의 HTN 환자는 이미 volume depleted state • Sympatholytic agents 또한 NL protective circulatory reflex 감소시킴

27. Induction(2) • 25%가량에서 endotracheal intubation후 severe hypertension 보임 • 가능한 한 duration of laryngoscopy 줄일 것 • Intubation은 deep anesthesia 상태에서 시행 • Intubation 전 Hypertensive response 줄이는 방법 • 강한 흡입마취제로 5-10분에 걸쳐 마취심도 깊게 • Bolus opiod(fentanyl 2.5-5㎍/㎏; alfentanil 15-25 ㎍/㎏; sufentanil 0.25-0.5 ㎍/㎏; remifentanil 0.5-1 ㎍/㎏) • Lidocaine 1.5㎎/㎏ iv or intratracheally • β-adrenergic blockade č esmolol 0.3-1.5㎎/㎏; propranolol 1-3㎎; labetalol 5-20㎎ • Topical airway anesthesia

28. Choice of anesthetic agentsa. Induction agents • Regional anesthesia에서도 HTN Pts.는 정상인보다 더 많은 혈압강하 보임 • 대부분 propofol, barbiturates, benzodiazepines, etomidate는 equally safe • Ketamine • Sympathetic stimulation때문에 elective op.에서 C/I • Benzodiazepine or propofol 소량 주입으로 상쇄가능

29. Choice of anesthetic agentsb. Maintenance agents • Volatile agents(±N2O), balanced technique (opioid + N2O + muscle relaxant), or totally IV techniques • Addition of volatile agent or IV vasodilator • Volatile agent • Vasodilation and relatively rapid & reversible myocardial depression => BP에 따라 titration 가능 • 일부에서는 sufentanil이 강한 autonomic suppression으로 BP control 가능하다고 주장

30. Choice of anesthetic agentsc. Muscle relaxants • Can be used routinely • Pancuronium • vagal blockade, neural release of catecholamines • Can exacerbate HTN in poorly controlled Pts • Large doses of tubocurarine, metocurine, atracurium, mivacurium은 hypotension 초래

31. Choice of anesthetic agentsd. Vasopressors • HTN Pts는 endogenous catecholamine이나 exogenous sympathetic agonist에 강한 반응 • Small dose of a direct-acting agent (phenylephrine 25-50㎍) • High vagal tone : small dose ephedrine (5-10㎎) • Sympatholytics 투여받았을 경우 드물게 epinephrine 2-5 ㎍필요할 수도 있음 • Improper dosing of epinephrine은 significant cardiovascular morbidity 초래 가능

32. Intraoperative hypertension • Anesthetic depth 높여도 반응 없을 경우 여러 parenteral agent로 치료 가능 • Antihypertensive therapy 시작 전 inadequate anesthetic depth, hypoxemia, hypercapnia 등 교정 가능한 원인부터 제거해야 함 • β-adrenergic blockade • Good ventricular function and elevated heart rate • C/I in bronchospastic disease • Nicardipine • Preferable for bronchospastic disease • Sublingual nifedipine의 reflex tachycardia는 MI 관련되며 delayed onset 지님

33. Intraoperative hypertension(2) • Nitroprusside • Most rapid and effective agent for the intraoperative treatment of moderate to severe HTN • Nitroglycerin • Less effective but useful in treating or preventing MI • Fenoldopam • Improve or maintain renal function • Hydralazine • Sustained BP control • Delayed onset, can cause reflex tachycardia • Reflex tachycardia는 labetalol 병용시 combined α- & β-adrenergic blockade 작용으로 없앨 수 있음

34. Intraoperative hypertension(3)

35. Postoperative management • 흔하며 poorly controlled HTN Pts에서 예측 가능 • Close BP monitoring in recovery room & early postop period • Marked sustained elevations in BP • MI and CHF • Formation of wound hematomas • Disruption of vascular suture lines • HTN in recovery period의 원인 • Respiratory abNL, pain, volume overload, bladder distention • Labetalol useful in HTN and tachycardia • Nicardipine useful in HTN with slow heart rate • 특히 MI가 예상되거나 bronchospasm 있을 경우 • Oral intake 가능해지면 수술전 medication 재개

36. ISCHEMIC HEART DISEASE

37. Preoperative considerations • O2 supply를 넘어서는 metabolic oxygen demand • Ischemia result from • Marked increase in myocardial metabolic demand • Reduction in myocardial O2 delivery • Common causes • Severe HT or tachycardia • Coronary arterial vasospasm or anatomic obx. • Severe hypotension, hypoxemia, anemia • Severe aortic stenosis or regurgitation

38. Preoperative considerations(2)Artherosclerosis of the coronary arteries • Major risk factors • Hyperlipidemia, HTN, diabetes, cigarette smoking • Increasing age, male sex, positive family history • Obesity, menopause, high estrogen oral pills • History of cerebrovascular or pph vascular disease • High estrogen oral contraceptives (with smoking) • Sedentary lifestyle,coronary-prone behavior pattern • Clinical manifestation • Sx of myocardial necrosis (infarction) • ischemia (usually angina) • Arrhythmias (including sudden death) • Ventricular dysfunction (CHF) => ischemic cardiomyopathy

39. Unstable angina • Defined as • 갑자기 증가하는 severity, frequency (1일 3회 이상), or duration of anginal attacks (crescendo angina) • Angina at rest • New onset of angina(2달 이내) with severe or frequent episodes(1일 3회 이상) • 대개 severe underlying coronary dis, MI를 동반 • 진단 및 치료 위해 coronary care unit 입원 필요 • Anticoagulation with heparin • Together with aspirin, iv nitroglycerin, β-blockers, calcium channel blockers • 24-48h내에 회복 없으면 coronary angiography통해 angioplastry or emergency surgical revascularization 시행

40. Chronic stable angina • Chest pain • Substernal, exertional, radiating to the neck or arm, relieved by rest or nitroglycerin • Nonexertional ischemia, silent ischemia도 흔함 • DM 환자에서 silent ischemia 동반 흔함 • 대개 artherosclerotic lesion이 50-75% occlusion 일으킬 때까지 증상 없음 • Stenotic segment가 70%에 이르러도 maximum compensatory dilatation으로 휴식시 blood flow는 유지되지만 increased metabolic demand에는 부족 • Emotional upset, hyperventilation등에 의한 coronary vasospasm 또한 transient transmural ischemia의 원인 (Prinzmetal’s angina)

41. Treatment of ischemic heart dis • The general approach • Progression을 늦추기 위해 coronary risk factor 교정 • Exercise tolerance 증대를 위해 lifestyle 교정 • Complicating medical condition 교정 • HTN, anemia, hypoxemia, thyrotoxicosis, fever, infection, adverse drug effects 등 • Pharmacological manipulation • Coronary lesion 교정 • Percutaneous coronary intervention • PCI (angioplasty with or without stenting, or atherectomy) • Coronary artery bypass surgery • Pharmacological agents • Calcium channel blockers : vasospastic angina • β-blockers :exertional angina & adequate ventricular function • Nitrates : both types of angina

42. Treatment of ischemic heart disa. nitrates • Relax all vascular smooth muscle (특히 vein) • 감소된 venous tone & return (cardiac preload) 은 wall tension과 afterload를 감소시켜 myocardial O2 demand를 감소시킴 • CHF 동반시 좋음 • Dilate coronary arteries • Flow는 radius의 4제곱에 비례하므로 stenotic site가 조금만 확장되어도 blood flow를 늘리기에 충분 • 특히 허혈부위의 subendocardial blood flow가 증가 • 이러한 효과는 collateral의 유무에 따름 • Acute ischemia 치료 및 frequent anginal episode의 예방에 쓰임 • Negative inotropic effect는 없음

43. Treatment of ischemic heart disb. calcium channel blockers • Cardiac afterload를 줄여 myocardial O2 demand를 감소시키고 • coronary vasodilation으로 blood flow를 늘려 O2공급을 증가시킴 • Verapamil과 diltiazem은 HR를 줄여 O2 demand 줄이기도 함 • Nifedipine – hypotension, reflex tachycardia • Sublingual 등 fast-onset preparation은 일부에서 MI를 일으키기도 함 • Afterload의 경감작용은 대개 negative inotropic effect를 상쇄할 수 있음 • Slow-release form : suitable for ventricular dysfunction • Amlodipine : similar to nifedipine but no effect on heart rate

44. Treatment of ischemic heart disb. calcium channel blockers(2) • Verapamil & diltiazem : greater effects on cardiac contractility & AV conduction • Ventricular dysfunction, conduction abNL, bradyarrhythmia 있을 시 더욱 주의하여야 함 • Diltiazem이 ventricular dysfunction있을 시 보다 적합 • Nicardipine & nimodipine : same effects as nifedipine • Nimodipine : SAH 후의 Cb vasospasm 방지 • Nicardipine : iv arterial vasodilator • Significant interactions with anesthetic agents • Potentiate neuromuscular blocking agents & circulatory effects of volatile agents • Verapamil : decrease anesthetic requirements • Verapamil & diltiazem : 마취가스에 의한 depression of cardiac contractility & conduction in the AV node를 강화시킴 • Nifedipine : volatile & iv agents에 의한 systemic vasodilation을 강화

45. Treatment of ischemic heart disc. β-adrenergic blocking agents • HR와 contractility를 줄여 myocardial oxygen demand를 감소시킴 • Optimal blockade : 휴식시 HR 50~60bpm, 운동시 지나친 증가 억제(<20bpm) • Membrane stabilization & Intrinsic sympathomimetic properties • Low dose : beneficial for compensated CHF • Nonselective β-receptor blockade • C/I in significant ventricular dysfunction, conduction abNL, bronchospastic dis. • β2-adrenergic receptors blockade • Can mask hypoglycemic Sx in awake DM Pt. • Delay metabolic recovery from hypoglycemia • Impair the handling of large potassium loads • Vasospastic angina에서도 C/I • Cardioselective agents(β1-specific) : selectivityrk dose dependent하므로 reactive airway Pt에게 주의 요구 • Acebutolol : β1-selectivity와 intrinsic sympathomimetic activiry를 모두 가지므로 bronchospastic airway dis. 때 유용

46. Treatment of ischemic heart disd. other agents • ACE inhibitors • Prolong survival in CHF or LV dysfunction • Digoxin • Rapid ventricular response 가능한 artrial fibrillation • Cardiomegaly Pt (특히 Sx 있을 경우) • Chronic aspirin therapy : reduce coronary events • Inducible sustained ventricular tachycardia or ventricular fibrillation • Automatic internal cardioverter-defibrillator (ICD) 적용 가능

47. Treatment of ischemic heart dise. combination therapy • Ventricular dysfunction Pt • Combined negative inotropic effect of β-blocker & calcium channel blocker에 견디지 못함 • ACE inhibitor가 survival 늘리는 데 더욱 효과 • Amlodipine & long-acting nitrate • 대개 significant ventricular dysfunction 환자에서 well tolerated • 일부에서는 과도한 vasodilation 일으킬 수도 있음

48. ISCHEMIC HEART DISEASE PREOPERATIVE MANAGEMENT

49. Perioperative outcome은 disease severity와 ventricular function에 관련 • Extensive(3-vessel or Lt main) CAD, recent Hx of MI, or ventricular dysfunction • => greatest risk for cardiac complications • 최근의 MI가 transmural or subendocardial 이어도 risk는 같음 • Perioperative MI 가 non-Q wave infarction이더라도 mortality rates는 50%에 이름 • Preop. PCI : cardiovascular Cx in high-risk Pt를 줄인다는 증거는 없음 • 또한 postsurgical bleeding을 막기 위해 PCI 이후 최소 2주는 경과하여야 함 • Chronic stable angina not increase perioperative risk • Coronary a. bypass surgery or coronary angioplasty Hx가 있는 경우에도 perioperative risk 증가하지 않음 • Preop. β-blocker • Periop. Mortality 및 postop. Cardiovascular Cx 감소 시킴

50. <Preop. Mx of Mj clinical predictorsof increased cardiovascular risk>