UEU-co logo

AccessMedicine

    Print   Close Window
Note: Large images and tables on this page may necessitate printing in landscape mode.

Copyright © The McGraw-Hill Companies.  All rights reserved.

CURRENT Diagnosis & Treatment in Cardiology > Chapter 36. Evaluation & Treatment of the Perioperative Patient >

Evaluation & Treatment of the Perioperative Patient: Introduction

The prevalence of cardiovascular disease and the death rate associated with it rises sharply after age 45, an age when the incidence of noncardiac surgeries is also increasing, and approximately one-third of the 25 million surgical procedures done annually are performed in patients with cardiovascular diseases. Cardiac deaths and nonfatal myocardial infarction (MI) occur in about 0.2% of all cases of general anesthesia and surgery (about 500,000 events annually). Cardiac deaths account for approximately 40% of all perioperative mortality, the same proportion as sepsis, although in many cases the cause of death is multisystem organ failure. These figures underestimate the total effect of cardiovascular diseases because another 500,000 persons a year suffer nonfatal MI, unstable angina, or congestive heart failure (CHF) perioperatively, prolonging both their time in the intensive care unit and the total hospital stay.

Although there is great potential to reduce perioperative cardiovascular risk, it is also impractical, unnecessary, and potentially harmful to perform cardiovascular testing in all patients prior to noncardiac surgery. Therefore, it is important to determine perioperative risk, decide whether cardiac testing is appropriate, and to provide prophylactic treatment to reduce risk.

Preoperative Risk Assessment

An individual patient’s preoperative risk profile depends on three main factors: the patient’s history, current medical and functional status, and the type of surgery. Preoperative electrocardiography can detect arrhythmia and prior silent MI, but it rarely changes management.

Table 36–1 lists cardiac risk based on type of noncardiac surgery. In the evaluation of perioperative patients, understanding the nature of the surgery is of prime importance. Is this an emergency surgery? If yes, the clinician should advise to proceed with the surgery and evaluate the patient’s cardiac risk postoperatively. On the other hand, if the patient is young, without systemic disease, and undergoing a minor surgery or procedure, the clinician should advise to proceed with surgery without further cardiac workup. However, most patients who require perioperative cardiac consultation are not so straightforward. In these patients, there are three algorithms that can help identify perioperative risk and the need for further cardiac testing.

Table 36–1. Cardiac Risk Stratification for Noncardiac Surgical Procedures According to ACC Guidelines.

   

High (Reported cardiac risk often greater than 5%)

   

Emergent major operations, particularly in the elderly

   

Aortic and other major vascular surgery

   

Peripheral vascular surgery

   

Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss

   

Intermediate (Reported cardiac risk generally less than 5%)

   

Carotid endarterectomy surgery

   

Head and neck surgery

   

Intraperitoneal and intrathoracic surgery

   

Orthopedic surgery

   

Prostate surgery

   

Low (Reported cardiac risk generally less than 1%)

   

Endoscopic procedures

   

Superficial procedure

   

Cataract surgery

   

Breast surgery

ACC, American College of Cardiology.

Reproduced with permission from Eagle KA, et al. Circulation. 2002;105:1251.

Algorithms

Revised Cardiac Risk Index (RCRI)

This algorithm is simple to use, and it helps identify patients who require -blockers perioperatively. However, the RCRI may have less accuracy in patients undergoing major vascular surgery. Use the RCRI as follows:

a. Assign 1 point to each of the following risk factors if present:

  • High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular).
  • Ischemic heart disease (history of MI or current angina, use of sublingual nitroglycerin, recent abnormal stress test, Q waves on electrocardiogram [ECG], or history of coronary revascularization with ongoing chest pain).
  • History of heart failure.
  • History of cerebrovascular disease (stroke, transient ischemic attack).
  • Diabetes mellitus requiring insulin.
  • Preoperative creatinine > 2.0 mg/dL.

b. Assign a risk class to determine cardiac complication rate to help counsel the patient and also the surgeon:

  • Class I: zero risk factors, 0.4%
  • Class II: one risk factor, 0.9%
  • Class III: two risk factors, 6.6%
  • Class IV: three or more risk factors, 11.0%

c. Patients who are categorized as having risk class III or IV will require additional cardiac testing for risk stratification and more aggressive perioperative medical management to reduce the risk of complications.

American College of Cardiology/American Heart Association (ACC/AHA) Guidelines

These guidelines are somewhat cumbersome (Figure 36–1). In simplified terms, the ACC/AHA guidelines recommend noninvasive cardiac stress testing in patients with two or more of the following risk factors:

  • Intermediate clinical predictors: mild angina, prior MI, compensated or prior heart failure, diabetes mellitus, or renal insufficiency.
  • Poor functional capacity (< 4 metabolic equivalents): cannot walk more than one or two blocks on level ground; cannot do light housework, such as washing dishes or dusting; cannot climb a flight of stairs or walk up a hill.
  • High-risk surgery: vascular surgery, prolonged procedure, or anticipated large fluid shifts or blood loss.

Figure 36–1.

American Heart Association/American College of Cardiology guidelines for preoperative evaluation prior to noncardiac surgery. CHF, congestive heart failure; ECG, electrocardiogram; METs, metabolic equivalents; MI, myocardial infarction.

(Reproduced, with permission, from Fleisher LA et al. J Am Coll Cardiol. 2007;50:1707.)

American College of Physicians (ACP) Guidelines

In general, the ACP guidelines advocate less perioperative cardiac testing while the ACC/AHA guidelines lean toward more perioperative cardiac testing. The ACP approach, which is also quite lengthy, is as follows:

a. Is the patient young, without systemic disease and undergoing a minor surgery? If yes, no further evaluation required. If no, proceed with further evaluation.

b. Is this an emergency surgery? If yes, no further evaluation required and recommend proceeding with the operation. If not, proceed with further evaluation.

c. Apply the Modified Cardiac Risk Index (assign points for each risk factor):

  • Coronary artery disease: MI < 6 months ago? 10 points; MI > 6 months ago? 5 points; angina walking one or two blocks or climbing one flight of stairs? 10 points; angina with any physical activity? 20 points.
  • Alveolar pulmonary edema: in last week? 10 points; ever? 5 points.
  • Suspected critical aortic stenosis? 10 points.
  • Arrhythmias: rhythm other than sinus? 5 points; more than five premature ventricular contractions/minute? 5 points.
  • Poor medical status? Any one of the following (PO  2 < 60 mm Hg, PCO 2 > 50 mm Hg, potassium < 3 mmol/L, creatinine > 3 mg/dL, blood urea nitrogen > 50 mg/dL, or bedridden): 5 points.
  • Age > 70 years: 5 points.
  • Emergency surgery: 10 points.

d. Add up points for above risk factors:

  • Score < 15: proceed to next step.
  • Score > 20: the patient is at high risk for cardiac complications. Optimize medical management and consider angiography or revascularization based on same criteria for nonsurgical patient.

e. Collect cardiac variables and assign risk:

  • Age over 70 years, angina, ECG evidence of ST-segment depression or of history of MI or Q waves ventricular arrhythmia, diabetes mellitus, hypertension with left ventricular hypertrophy, history of heart failure.
  • If the patient has fewer than two of the above variables, he or she is at low risk for cardiac complications and no further testing is needed.
  • If the patient has two or more of the above variables, he or she is at intermediate risk for cardiac complications; proceed to next step.

f. Is the patient undergoing vascular surgery? If the answer is no, additional testing is not necessary. If the answer is yes, proceed to next step (noninvasive cardiac stress testing).

g. Perform noninvasive cardiac stress testing. If the test results are normal, no further testing is needed. If the results are abnormal, consider angiography or revascularization based on the same criteria as for the nonsurgical patient.

Intermediate Risk Patients

While perioperative management of low-risk and high-risk patients is relatively straightforward, the management of patients who fall into the intermediate risk is more challenging. Low-risk patients can proceed to surgery without further cardiac evaluation. For high-risk patients, management should include one or more of the following: postpone or cancel surgery until high-risk features improve or resolve, start treatment of the underlying high-risk features, or proceed to invasive testing. In high-risk patients with a high pretest probability of disease, noninvasive tests are not helpful, because a negative result will most likely be a false negative.

Intermediate-risk patients derive the most benefit from perioperative medical management or stress testing, or both.

For most patients in the intermediate risk category, it is important to obtain imaging with the stress test because ECG alone is unlikely to move the posttest probability beyond the threshold for treatment or no treatment.

Exercise versus Pharmacologic Stress Testing

The choice between exercise and pharmacologic stress testing follows the same guidelines as those for routine, nonperioperative stress testing. Exercise testing can provide valuable information on functional capacity, but patients may not be able to reach 85% of maximal predicted heart rate due to deconditioning or -blocker use. Since -blockers are important in the perioperative period, withholding them is not ideal.

Dipyridamole or adenosine is preferred in cases where arrhythmia (eg, rapid atrial fibrillation) or frequent premature atrial or ventricular beats are present. These agents are relatively contraindicated in patients with significant bronchospasm, in whom dobutamine is the agent of choice.

Type of Imaging Technique

When choosing either echocardiography or nuclear imaging (the two most commonly available stress imaging modalities), it is most important to determine which modality has better reliability and expertise at the clinician’s hospital or clinic. In published studies, both imaging techniques have good negative predictive value (> 90%) but poor positive predictive value (< 25%). Echocardiography with contrast (to assist in endocardial border definition) may be more helpful in obese patients (who may have more attenuation defects on nuclear imaging). Nuclear imaging may be more useful in patients with left bundle branch block and when atrial fibrillation is present. Newer modalities include rubidium positron emission tomography (PET) scanning, which provides better resolution images. However, patients must be cooperative and must be able to hold still for longer periods of time. Cardiac computed tomography provides anatomic assessment of the coronary arteries but does not provide data on ischemic burden, and has not been adequately evaluated in the perioperative setting.

Understanding Cardiac Complications

Despite the risks during general anesthesia, including myocardial depression, transient hypotension, and tachycardia, very few cardiac events occur during the surgery itself. The incidence of perioperative cardiac complications actually peaks between 2 and 5 days postoperatively. These data imply that factors activated during or following surgery, and not only the surgery itself, are crucial in determining adverse outcomes.

Pneumonitis and microatelectasis produce ventilation-perfusion mismatch, and sedation or analgesia may cause respiratory depression and interfere with coughing, all of which contribute to arterial hypoxemia. Thrombocytosis and a generalized hypercoagulable state, caused by increased fibrinogen and activators from the damaged tissue, favor thrombosis. At the same time, sympathetically mediated increases in heart rate, blood pressure, and contractility increase myocardial oxygen consumption, whereas thrombotic tendencies, anemia, and arterial desaturation impede oxygen delivery to the myocardium. In a patient with underlying coronary artery disease, this situation may lead to myocardial ischemia or infarction. The imbalance may be further exaggerated because antihypertensive or anginal medications are often withheld. By the third or fourth postoperative day, the patient is hypermetabolic, with negative nitrogen and potassium balances. A natriuresis follows, which can produce hypovolemia and further activate the sympathetic nervous system.

All of these factors provide the exact setting in which a perioperative MI may occur. Perioperative MI carries a high mortality and presents atypically (usually without chest pain). Clues such as hypotension, pulmonary edema, altered mental status, and arrhythmia may be the only signs alerting the clinician to the possibility of a perioperative MI. Therefore, those caring for perioperative patients must have a high level of suspicion in order to detect perioperative MI.

Fleisher LA et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). J Am Coll Cardiol. 2007;50:1707–32. [PMID: 17950159]

Guidelines for assessing and managing the perioperative risk from coronary artery disease associated with major noncardiac surgery. American College of Physicians. Ann Intern Med. 1997;127(4):309–12. [PMID: 9265433]

Treatment to Reduce Perioperative Risk

Knowledge of how new therapies can reduce cardiac risk has progressed rapidly in recent years. Perioperative medicine now provides “risk management” (through medicine such as -blocker) in addition to the standard risk prediction. In general, the higher the patient’s risk, the greater benefit derived from the use of therapies such as -blockers and statins. Therefore, healthcare providers should use the Revised Cardiac Risk Index (see above) to stratify patients, and then use this to determine whether or not to treat.

-Blockers

These agents are first-line therapy to reduce perioperative morbidity and mortality in high-risk patients. Current guidelines have advocated -blockers in almost all intermediate- or high-risk patients undergoing noncardiac surgery. However, two recent studies in vascular surgery patients did not show a benefit, and a meta-analysis of seven randomized controlled trials did not conclusively show a benefit with -blockers. Another recent retrospective review of 600,000 patients showed that -blocker benefit was greater in higher-risk patients. Therefore, the decision to use -blockers should be individualized. If the patient is already taking a -blocker for other reasons (eg, coronary artery disease), -blockers should be continued in the perioperative setting. Patients with an RCRI score (see above) of three benefit from -blockers, while those with an RCRI score of zero are harmed by -blockers.

In patients deemed to benefit from -blockers in the perioperative setting, oral metoprolol is started on the day of the perioperative visit. For patients who were taking -blockers before the surgery, the dose is titrated to a heart rate of 60 bpm. Postoperatively, metoprolol is started at 5–10 mg intravenously every 4–6 hours as needed to keep the heart rate 60–70 bpm until the patient can take oral medications. Oral -blockers are then continued for 30 days postoperatively and indefinitely in patients who were previously taking these medications.

Statins

One small randomized controlled trial and several observational studies have found a benefit to statin use, with greater benefit in higher risk patients. Therefore, if there are no major contraindications, intermediate- and high-risk patients should be taking a statin prior to major noncardiac surgery.

Clonidine

There is evidence that clonidine (an 2-adrenergic agonist) reduces MI and mortality in high-risk vascular surgery patients. Clonidine’s transdermal delivery system works well in the perioperative setting, but clonidine is not ideal for outpatient management and carries the risk of rebound hypertension. For these reasons, clonidine should not be used routinely but can be a good choice for in-hospital control of hypertension in the perioperative patient who cannot take oral medications.

Calcium Channel Blockers

Verapamil and diltiazem (centrally acting calcium channel blockers) are second-line therapy for reducing perioperative ischemia or arrhythmia, or both. Use in high-risk patients who have a contraindication to -blockers.

Maintanence of Normothermia

Maintaining normal body temperature is easy to perform, low risk, and has been shown to significantly reduce perioperative cardiac events in high-risk patients undergoing major abdominal or vascular surgery.

Deep Venous Thrombosis Prophylaxis

Although not a routine part of perioperative cardiac risk assessment and treatment, it is important to check for appropriate perioperative deep venous thrombosis (DVT) prophylaxis since DVT (with resultant pulmonary embolism) can cause significant cardiac instability and death. Low-molecular-weight-heparins are being used increasingly in place of unfractionated heparin and appear equivalent or, in some cases, superior.

Endocarditis Prophylaxis

Recommendations for management of endocarditis prophylaxis have changed dramatically with the publication of the new AHA guidelines. In general, the new AHA guidelines advocate less use of antibiotic prophyalxis because of the lack of evidence of benefit in humans, and the fact that transient bacteremia occurs frequently, and there is no evidence that dental and other procedures increase rates of bacteremia more than activities of daily living alone. The AHA guidelines state that only patients at the highest risk for endocarditis should receive antibiotic prophylaxis. These high-risk patients include those with prosthetic cardiac valve, previous infective endocarditis, unrepaired cyanotic congenital heart disease (including palliative shunts and conduits), completely repaired congenital heart defect with prosthetic material or device during the first 6 months post-procedure, repaired congenital heart defects with residual defects at site of prosthetic material which prevent endothelialization, and patients who have undergone heart transplantation in whom significant valvular heart disease develops.

Prophylaxis for dental procedures in the aforementioned patients is only recommended if the procedure involves manipulation of gingival tissue, manipulation of periapical region of teeth, or perforation of the oral mucosa.

Endocarditis prophylaxis is no longer recommended for genitourinary or gastrointestinal procedures.

Perioperative Medication Management

Management of outpatient medications in the perioperative period is underappreciated but extremely important for ensuring an optimal patient outcome. Many times, essential medications are discontinued and not restarted before the patient is discharged from the hospital, leading to potentially disastrous outcomes. Other times, the conversion of oral to intravenous (and back to oral) dosing of medications causes under- or over-treatment.

Anticoagulation Management

Nowhere is perioperative medication management more important than in anticoagulation, since use of anticoagulants can cause increased bleeding intra- and post-operatively. Alternatively, too little anticoagulation can lead to severe morbidity (eg, stroke, MI, and stent thrombosis) and even death.

Warfarin

One of the most common reasons for cardiac consultation (besided assessing perioperative risk) is to manage warfarin perioperatively. Although the risks of discontinuing warfarin therapy 4 days prior to surgery are low, in the few patients in whom thromboembolism develops, the results (stroke, pulmonary embolism, MI, or death) can be devastating. Therefore, in high-risk patients, bridging with unfractionated or intravenous heparin is important and can reduce perioperative risk of thromboembolism. However, use of heparins can increase bleeding. Therefore, it is important to carefully select patients who will need bridging with heparin. The keys to optimal warfarin management is to identify the indication for warfarin, and assess the patient’s risk for thromboembolism. Bridging with heparin is advised in the following situations: (1) atrial fibrillation and rheumatic heart disease, history of thromboembolism, or mechanical heart valve; (2) older mechanical heart valve in mitral position (single-disk or caged-ball), or recently placed mechanical valve (< 3 months); or (3) hypercoagulable state, venous or arterial thromboembolism in prior 3 months, acute intracardiac thrombus visualized on echocardiogram.

Bridging is advised on a case-by-case basis (weighing risks and benefits) in patients with significant (recurrent) cerebrovascular disease, newer model mechanical valve (ie, bileaflet tilting disk) in mitral position, older mechanical valve in aortic position, atrial fibrillation with multiple risk factors for cardiac embolism, and history of venous thromboembolism (> 3 months ago). Bridging is not advised in patients with a newer-model mechanical valve in the aortic position, atrial fibrillation without multiple risk factors for cardiac embolism, or in patients with a history of one remote (> 6 months ago) venous thromboembolism.

Warfarin should be stopped 4 days prior to surgery if preoperative INR is 2.0–3.0 (with modification of timing if INR is < 2.0 or > 3.0). In patients who require bridging with a heparin, there is evidence that low-molecular-weight heparin (eg, enoxaparin) is just as effective and safe (if not more so) than unfractionated heparin. Enoxaparin (1 mg/kg twice daily), if not contraindicated, is started 36 hours after the last dose of warfarin and is discontinued 24 hours prior to surgery. On postoperative day 1, warfarin is restarted at the preoperative outpatient dose. At 24 hours postoperatively, the patient is evaluated and enoxaparin is restarted if hemostasis has been achieved. Once INR is in the therapeutic range, enoxaparin can be discontinued.

Aspirin and Clopidogrel

Controversy exists regarding the optimal management of antiplatelet therapy in patients undergoing noncardiac surgery, especially in patients with drug-eluting stents. It appears that decreased endothelialization of drug-eluting stents predisposes these patients to stent thrombosis for quite some time after stent placement.

In patients who do not have a coronary stent and who are at low risk for perioperative cardiac events, aspirin and clopidogrel should be discontinued 7–10 days prior to noncardiac surgery.

In patients with coronary stents, especially drug-eluting stents, the risk of stent thrombosis greatly increases when aspirin and clopidogrel are stopped prematurely. Recent AHA/ACC guidelines state that aspirin and clopidogrel should not be discontinued for at least 1 month after bare metal stent and for at least 12 months after the placement of a drug-eluting stent. If surgery cannot be deferred, aspirin should be continued in the perioperative period, and in extremely high-risk patients, intravenous glycoprotein IIb–IIIa inhibitors (which have a shorter half-life than clopidogrel) can be used to try to prevent stent thrombosis (although the increased risk of significant bleeding must also be taken into consideration).

It is now clear that cardiologists must discuss with their patients the need for prolonged dual antiplatelet therapy prior to percutaneous coronary intervention, so that if noncardiac surgery is possible in the near future, drug-eluting stents should be avoided.

Antiarrhythmics

These medications should be continued up to the day of surgery, and if necessary in the immediate postoperative period (in an intravenous form).

Amiodarone is a common oral antiarrhythmic that needs to be converted to an intravenous format in the perioperative period. Since intravenous bolus of amiodarone can cause hypotension, it is more ideal to add up the total daily oral dose of amiodarone and convert that dose to a prolonged or continuous infusion (eg, instead of giving 200 mg intravenously as a bolus once daily, give 0.15 mg/min intravenously continuously over 24 hours, or give the 200 mg intravenously over a 4–6 hours).

Digoxin dose should generally be reduced slightly in the perioperative period, especially in elderly patients or those in whom worsening renal function is to be expected.

Nonsteroidal Antiinflammatory Drugs (NSAIDs)

These medications can predispose elderly and other high-risk patients to perioperative renal failure, especially with perioperative dehydration and hypotension. Therefore, NSAIDs should be discontinued at least 3 days prior to surgery and restarted if necessary upon discharge from the hospital.

Prophylactic Coronary Revascularization

For patients who are intermediate or high-risk, and who eventually undergo coronary angiography, there are three possibilities: no significant coronary artery disease, left main or triple-vessel coronary artery disease, and single- or two-vessel coronary artery disease.

No Significant Coronary Artery Disease

Noncardiac surgery can proceed without further testing, although perioperative risk reduction with -blockers and other agents will be important.

Left Main or Triple-Vessel Coronary Artery Disease

These patients, who are on the opposite extreme, are very high-risk and should undergo prophylactic coronary artery bypass grafting. Alternatively, in institutions with expertise, percutaneous coronary intervention is another possibility.

Single- or Two-Vessel Coronary Artery Disease

In these patients, the decision for prophylactic revascularization is more difficult. The Coronary Artery Revascularization Prophylaxis (CARP) trial showed that in patients with single- or two-vessel coronary artery disease (> 70% stenosis) undergoing noncardiac vascular surgery, prophylactic revascularization was no better than medical management for the prevention of short- and long-term perioperative cardiac events. It is important to note that all patients underwent coronary angiography and those with triple-vessel or left main coronary artery disease were excluded from the trial. Therefore, in patients found to have single- or two-vessel coronary disease, medical management in the perioperative period, even before high-risk vascular surgery, is just as safe as prophylactic revascularization and does not delay noncardiac surgery. If patients must undergo percutaneous coronary intervention preoperatively, balloon angioplasty alone avoids the necessity to continue dual antiplatelet therapy. If stents are placed, it is extremely important to follow recommendations for perioperative management of aspirin and clopidogrel (see section on Perioperative Medication Management above).

Auerbach AD et al. Beta-blockers and reduction of cardiac events in noncardiac surgery: scientific review. JAMA. 2002 Mar 20;287(11):1435–44. [PMID: 11903031]

Auerbach AD. Perioperative cardiac risk reduction: doing it right. Cleve Clin J Med. 2006 Mar;73 Suppl 1:S25–9. [PMID: 16570544]

Devereaux PJ et al. How strong is the evidence for the use of perioperative beta blockers in non-cardiac surgery? Systematic review and meta-analysis of randomized controlled trials. BMJ. 2005 Aug 6;331(7512):313–21. [PMID: 15996966]

Durazzo AE et al. Reduction in cardiovascular events after vascular surgery with atorvastatin: a randomized trial. J Vas Surg. 2004 May;39(5):967–75. [PMID: 15111846]

Grines CL et al; American Heart Association; American College of Cardiology; Society for Cardiovascular Angiography and Interventions; American College of Surgeons; American Dental Association; American College of Physicians. Prevention of premature discontinuation of dual antiplatelet therapy in patients with coronary artery stents: a science advisory from the American Heart Association, American College of Cardiology, Society for Cardiovascular Angiography and Interventions, American College of Surgeons, and American Dental Association, with representation from the American College of Physicians. Circulation. 2007 Feb 13;115(6):813–8. [PMID: 17224480]

Jaffer AK. Anticoagulation management strategies for patients on warfarin who need surgery. Cleve Clin J Med. 2006 Mar;73 Suppl 1:S100–5. [PMID: 16570558]

Lindenauer PK et al. Lipid-lowering therapy and in-hospital mortality following major noncardiac surgery. JAMA. 2004 May 5;291(17):2092–9. [PMID: 15126437]

Lindenauer PK et al. Perioperative beta-blocker therapy and mortality after major noncardiac vascular surgery. N Engl J Med. 2005 Jul 28;353(4):349–61. [PMID: 16049209]

McFalls EO et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med. 2004 Dec 30;351(27): 2795–804. [PMID: 15625331]

Poldermans D et al. Statins are associated with a reduced incidence of perioperative mortality in patients undergoing major noncardiac vascular surgery. Circulation. 2003 Apr 15;107(14): 1848–51. [PMID: 12695283]

Wijeysundera DN et al. Alpha-2 adrenergic agonists to prevent perioperative cardiovascular complications: a meta analysis. Am J Med. 2003 Jun 15;114(9):742–52. [PMID: 12829201]

Wijeysundera DN et al. Calcium channel blockers for reducing cardiac morbidity after noncardiac surgery: a meta-analysis. Anesth Analg. 2003 Sep;97(3):634–41. [PMID: 12933374]

Wilson W et al; American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee; American Heart Association Council on Cardiovascular Disease in the Young; American Heart Association Council on Clinical Cardiology; American Heart Association Council on Cardiovascular Surgery and Anesthesia; Quality of Care and Outcomes Research Interdisciplinary Working Group. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation. 2007 Oct 9;116(15):1736–54. [PMID: 17446442]

Special Populations

Vascular Surgery

Of all noncardiac surgeries, intra-abdominal and intrapelvic vascular surgeries are perhaps the highest risk because of the nature of the surgery and the nature of the patients who have peripheral vascular disease, since many of these patients have significant coronary risk factors and coronary artery disease.

For patients undergoing elective high-risk vascular surgery, the ACC/AHA guidelines are useful for determining whether these patients need further risk stratification with noninvasive cardiac testing. Kertai and colleagues have published a more detailed risk prediction model, customized for type of vascular surgery, which may be useful in cases where level of risk is not obvious, or for surgeons, patients, or families who want a more detailed risk assessment.

In patients who require coronary angiography because they are high-risk, or because they are intermediate risk with an abnormal stress test, the results of the CARP trial (see above under Prophylactic Coronary Revascularization) help clinicians better understand which patients can be adequately treated with medical therapy alone.

Aortic Stenosis

In patients with severe or critical aortic stenosis, risks of a perioperative cardiac complication are very high. The risk correlates with aortic valve mean gradient, as measured by echocardiography. Even moderate aortic stenosis (mean gradient of > 25 mm Hg) has been associated with an adjusted relative risk of 5.2 for perioperative cardiac complications.

Noninvasive stress testing is unnecessary and potentially dangerous in these patients. If the patient has symptomatic aortic stenosis, postpone the noncardiac surgery until after the patient undergoes coronary angiography, aortic valve replacement, and coronary artery bypass grafting (if the patient is found to have significant coronary artery disease). In asymptomatic patients with severe aortic stenosis, preoperative aortic valve replacement (prior to elective noncardiac surgery) is usually the best option because of the very high-risk nature of these patients. If aortic valve replacement is not an option, percutaneous aortic valvuloplasty can be considered, though it carries a significant risk of thromboembolism and aortic stenosis recurrrence. These risks must be weighed against the risk of cancelling surgery or operating with significant aortic stenosis.

Heart Failure

Patients with a history of hospitalization for heart failure, and especially those with current signs and symptoms of heart failure, are at high risk for perioperative cardiac events. In these patients, heart failure should be treated and volume status optimized prior to surgery, since the risks of heart failure outweigh the need for surgery in most cases. As the number of patients with heart failure increases along with the aging population, more patients who undergo noncardiac surgery will have a history of heart failure. Even though heart failure is a greater risk of perioperative cardiac events than coronary artery disease, there are few studies on the optimal perioperative treatment of patients with heart failure, especially those with preserved ejection fraction.

Pulmonary Hypertension

In patients with significant pulmonary hypertension, the risks of general anesthesia are extraordinarily high. Pulmonary hypertension can be thought of as a fixed obstruction to cardiopulmonary blood flow, and therefore prevents increase in cardiac output necessary in the perioperative state. It is therefore very similar to critical aortic stenosis in this aspect. In these cases, a pulmonary hypertension specialist should be consulted. Elective surgeries should be postponed indefinitely until the patient is treated with vasodilators to reduce the perioperative risk. If surgery is absolutely necessary, it is advisable that these patients undergo continuous monitoring with pulmonary artery catheter intraoperatively. Intraoperative inhaled nitric oxide can be used to decrease pulmonary artery pressures.

Pacemakers and Defibrillators

There is a small risk that prolonged electrocautery could trigger, reprogram, or inadvertently offset an implantable cardioverter defibrillator (ICD). Electrocautery may also interfere with pacemaker output and anesthetic agents may interfere with pacing thresholds. Some manufacturers have recommended that the device be inactivated during surgery. Supraventricular tachycardias, which are fairly common in the postoperative period, may exceed the rate threshold of the ICD and can cause inappropriate shocks to be delivered. Implantable cardioverter defibrillators should be interrogated before surgery to assess underlying rhythm and frequency of discharges. In pacemaker-dependent patients, the rate response feature should be tuned off. The ICD defibrillation capacity should be disengaged just prior to surgery and resumed immediately after surgery, and an external defibrillating device with personnel able to handle it should be close to the patient at all times during the period that the ICD is off. Of note, an anteroposterior lead placement of the external pacer paddles away from the device pocket is required in the event of external cardioversion or defibrillation.

Christ M et al. Preoperative and perioperative care for patients with suspected or established aortic stenosis facing noncardiac surgery. Chest. 2005 Oct;128(4):2944–53. [PMID: 16236971]

Kertai MD et al. Aortic stenosis: an underestimated risk factor for perioperative complications in patients undergoing noncardiac surgery. Am J Med. 2004 Jan 1;116(1):8–13. [PMID: 14706659]

Kertai MD et al. Optimizing the prediction of perioperative mortality in vascular surgery by using a customized probability model. Arch Intern Med. 2005 Apr 25;165(8):898–904. [PMID: 15851641]

Copyright © The McGraw-Hill Companies.  All rights reserved.
Privacy Notice. Any use is subject to the Terms of Use and Notice.

McGraw-Hill Education A Silverchair Information System The McGraw-Hill Companies

Leave a Reply


Time limit is exhausted. Please reload the CAPTCHA.

Categories

apply_now Pepperstone Group Limited