Key Points
- 1.
Perioperative triage should determine whether cardiac patients receive outpatient surgery, routine inpatient care, or critical care services.
- 2.
Advanced hemodynamic monitoring may be required in high-risk patients with cardiac disease undergoing noncardiac surgery, including direct arterial pressure measurements, filling pressures, echocardiography, and cardiac outputs.
- 3.
Patients with stable or unstable coronary artery disease (CAD) are commonly seen for noncardiac surgery. The unstable patients present a very high risk and have an increased mortality rate. Perioperative myocardial infarctions are difficult to diagnose and have a poor outcome.
- 4.
The new 2017 guidelines for hypertension have markedly increased the number of patients with this disorder. Many more patients will be seen on antihypertensive therapy when coming for noncardiac surgery. In general, their therapies should be continued throughout surgery, with the possible exception of those drugs that block the renin-angiotensin system.
- 5.
The outcome of patients with heart failure (HF) is worse than that of patients with isolated CAD in the perioperative period. Thus complete evaluation and maximum therapy should be used to reduce morbidity and mortality.
- 6.
Takotsubo cardiomyopathy is a syndrome related to excessive catecholamines and must be differentiated in the surgical patient from acute coronary syndromes or HF. Usually the distinction can be made with echocardiography, and the outcome is often good.
- 7.
The most common types of valvular heart disease seen in noncardiac surgical patients are aortic stenosis and mitral regurgitation. The therapeutic goals and principles used to manage these patients should be similar to those used during cardiac surgery.
- 8.
Atrial fibrillation is the most common arrhythmia seen in older adult patients. Many of these patients are taking anticoagulants to reduce the incidence of stroke. These drugs must be managed well in surgical patients.
- 9.
The new oral anticoagulants consist of a direct thrombin inhibitor, dabigatran, and three factor Xa inhibitors. These drugs have marked advantages over the older warfarin-type anticoagulants. However, experience with them in the perioperative period is still developing, especially regarding the use of regional anesthetic techniques.
Approximately 230 million surgical procedures are performed worldwide each year. Perioperative mortality rates are relatively low, but this may be a misleading fact because complications continue to be significant. In fact, high-risk patients may have a postoperative complication rate as high as 50%. This subset of patients accounts for only 13% of all surgical procedures but more than 80% of postoperative deaths. The management of these high-risk patients in the perioperative period presents a unique challenge for perioperative physicians. This chapter focuses on the perioperative management of “high-risk” complex cardiac patients for noncardiac surgery, with additional discussion of common diseases.
Perioperative Triage
Defining which patients are appropriate for various perioperative care areas, whether it is outpatient surgery, routine inpatient care, or critical care services, is vital. Triage can be defined as the process of deciding which patients should be treated first based on degree of sickness or severity of injury. In the present value-based health care system, placing the “right” patients in the “right” places is a difficult but crucial task.
Ambulatory Surgery
A challenging triage decision is identifying which surgical patients are best cared for in hospital-based versus ambulatory settings. Adequate preoperative patient assessment is important in determining the appropriate surgical environment. Criteria associated with increased hospital admission after outpatient surgery include age 65 years or older, cardiac diagnoses, peripheral vascular disease, surgery lasting more than 2 hours, cerebrovascular disease, malignancy, HIV diagnosis, and general anesthesia. Data evaluating 5 years of common ambulatory-eligible surgical procedures (≈250,000 procedures) suggest the following risk factors are associated with an increase in morbidity and mortality: previous cardiac surgical intervention (percutaneous coronary intervention [PCI] or cardiac surgery), overweight or obese body mass index, chronic obstructive pulmonary disease, prior transient ischemic attack or stroke, hypertension, and prolonged surgical time ( Table 2.1 ). Patients with stable coronary artery disease (CAD) may not be at higher risk for perioperative complications after ambulatory surgery. Additionally, patients with cardiac pacemakers or implantable cardioverter-defibrillators can be evaluated for ambulatory surgical cases. Important information includes the type and function of these devices before proceeding with surgery. Similarly, it is appropriate to develop a definitive perioperative plan for the management of these devices (in terms of electromagnetic interference and follow-up) (see Chapter 4 ).
| Factors Associated With ICU Admission | Factors Associated With Increased Hospital Admission After Outpatient Surgery | Factor Associated With Increased Risk of Morbidity or Mortality After Day Case–Eligible Procedures |
|---|---|---|
| Surgical patients (vs. medical patients) | Age >65 y | Previous cardiac surgical intervention (PCI or cardiac surgery) |
| Absence of comorbidities | Cardiac diagnoses | Overweight or obese BMI |
| Presence of hematologic malignancy | Peripheral vascular disease | COPD |
| Acute clinical condition | Malignancy | History of TIA or CVA |
| Need for active intensive care therapies | HIV | Hypertension |
| Trauma | General anesthesia | Prolonged surgical time |
| Vascular involvement | Surgery >2 h | |
| Hepatic involvement | ||
| Acute severity of illness | ||
| Lowest surgical Apgar score |
a Depicts the factors associated with ICU admission, increased hospital admission after outpatient surgery, and factors associated with heightened risk for morbidity and mortality after outpatient procedures.
Critical Care Services
Triaging healthy and moribund patients away from critical care services (excluding palliative services and services to those who are brain dead) seems to be relatively straightforward. However, healthcare providers are challenged by a scarcity of intensive care unit (ICU) beds and an inherent cost in determining which patients will truly benefit from intensive care. Improving preoperative evidence-based strategies to identify which patients are at highest risk for postoperative complications may aid in determining patient need. Similarly, reducing hospital variability in managing these patients when they develop postoperative complications is also paramount to reducing morbidity and mortality. Approximately 30% of patients accepted for ICU services have cardiac diseases.
Observational studies also outline the potential benefit of ICU admission for older adult patients, suggesting a greater mortality reduction in older adult patients admitted to ICUs compared with younger patients. Based on these findings, intensivists may consider accepting even older adults who appear “well.”
Studies evaluating intraoperative events such as blood loss have shown a reduction in mortality rate with ICU admission. Intraoperative hemodynamics and blood loss should indeed influence ICU triage.
Triaging Patients With Coronary Stents for Noncardiac Surgery
One of the largest observational studies to date reported an approximately 23% rate of noncardiac surgery 1 year after PCI. Multiple guidelines report that elective surgery should be delayed for at least 4 to 6 weeks after bare-metal stent (BMS) placement and 6 to 12 months after drug-eluting stent (DES) placement, depending on the type of stent. The major challenge is determining the risk of perioperative surgical hemorrhage versus dual antiplatelet therapy (DAPT) interruption, and its relation to subsequent coronary stent thrombosis (see Chapter 3 ).
A safe time period for antiplatelet therapy interruption has yet to be clearly defined. Still, the continuation of aspirin is often recommended throughout the perioperative period. In the absence of guidelines supported by strong evidence, it may be important for the care team (primary care doctor, cardiologist, perioperative physicians) to collaborate and develop a definitive perioperative plan regarding continuation of DAPT, type and timing of stent placement, and disposition. Risk factors such as those mentioned may lead the perioperative team to suggest hospital-based surgery with the potential for an overnight stay and monitoring.
Cardiovascular System
Cardiac issues remain a significant contributor to perioperative morbidity and mortality. The intraoperative management of cardiac complications in noncardiac surgery is discussed below with a focus on CAD, hypertension, heart failure (HF), valvular heart disease, and rhythm disturbances.
Patients with underlying cardiac disease may require advanced monitoring throughout the perioperative period. However, there is limited evidence to establish clear guidelines, and clinical discretion is advised. Invasive arterial pressure monitoring may be considered in patients requiring pharmacologic therapy to stabilize blood pressure (BP) or cardiac function. Central venous access may be needed for drug or fluid administration, but central venous pressure monitoring may not reliably reflect intravascular volume status or fluid responsiveness. The role of pulmonary artery catheters in noncardiac surgical and critically ill patients continues to be controversial and depends on local practice patterns. Transesophageal echocardiography (TEE) or focused transthoracic echocardiography (TTE) may serve as an important monitor in the operating room to evaluate cardiac function and fluid status. An understanding of common cardiac diseases will help perioperative clinicians gauge the level of monitoring and care that is appropriate for each unique scenario.
Coronary Artery Disease
Patients with or at risk for CAD present significant challenges to anesthesiologists in the perioperative period. As many as 5% of patients with CAD undergoing noncardiac surgery may develop cardiac complications. Risk factors include a history of ischemic heart disease, HF, stroke, diabetes mellitus, or renal insufficiency. Preoperative risk stratification is discussed in detail in Chapter 1 . Perioperative acute coronary events may range from myocardial ischemia or myocardial injury to myocardial infarction (MI). MI is universally defined as an elevation of cardiac biomarkers such as troponin, electrocardiographic (ECG) changes, new regional wall motion abnormalities seen on echocardiography, or coronary catheterization findings consistent with acute blockages.
The perioperative management of acute coronary syndrome (ACS), unstable angina, or acute MI presents a unique challenge because these patients under anesthesia or sedated postoperatively may not have the same signs and symptoms often seen in nonoperative patients. In fact, one large study found that 65% of patients with perioperative MI did not have symptoms. Thus the diagnosis is often confirmed only when clinical suspicion leads to further laboratory testing or investigation. When patients do complain of symptoms or clinical suspicion exists, clinicians should obtain a 12-lead ECG and serial cardiac biomarkers (e.g., troponin). Cardiology consultation for risk stratification, further testing, and therapy may be warranted.
Unlike nonsurgical patients with ACS or MI, care pathways for perioperative patients are not well studied. Unique concerns such as bleeding risk, surgical stressors, and perioperative physiologic changes make protocols for therapy very challenging. Management must be considered in context for each patient and the relative risk-to-benefit ratio of therapies applied uniquely.
Patients with ACS preoperatively must first be clinically stabilized. Therapies to augment cardiac output may be needed. Administration of β-adrenergic agonists (e.g., dobutamine [2.5–5 µg/kg per minute] or epinephrine [1–2 µg/min]) can be effective. Mechanical augmentation with devices such as an intraaortic balloon pump or axial-flow pumps may be considered in severe cases. Arrhythmias may occur and should be managed, but prophylactic lidocaine is not indicated.
Medical therapy with aspirin (162–325 mg) should be initiated if not contraindicated. Additional antiplatelet therapy with a P2Y 12 receptor blocker is indicated in ACS, but may not be safe in the perioperative period. In patients with non–ST segment elevation ACS or MI (non-STEMI), systemic anticoagulation (i.e., heparin infusion) may be indicated, but the risk of surgical bleeding must be weighed against the risk of advancing ACS. Oxygen should be administered to all hypoxemic patients in concentrations needed to achieve normoxia. There are no data to support the use of oxygen in patients with MIs and normal oxygen saturation. Nitroglycerin may be administered to patients with angina, but should be avoided in patients with severe aortic stenosis (AS), right ventricular infarction, hypotension, or a history of phosphodiesterase inhibitor use in the previous 24 hours. Caution should also be used with this vasodilator in patients under neuraxial anesthesia because this could precipitate hypotension. Pain control with opioid analgesics may be considered; however, evidence suggests that morphine may be detrimental in patients with ACS. Proposed mechanisms include a morphine-induced impaired absorption or effectiveness of certain antiplatelet therapies. Statin therapy is indicated as soon as possible ( Box 2.1 ).
Box 2.1- •
Oxygen to maintain normoxia
- •
Aspirin 162–325 mg
- •
P2Y 12 antiplatelet therapy
- •
Systemic anticoagulation (if no contraindication)
- •
Nitroglycerin for pain (if no contraindication)
- •
Opioid analgesics as needed
- •
β-Blockers if stable
- •
Statin therapy as soon as possible
β-Blocker therapy is perhaps the most controversial perioperative cardiac therapy. Although several studies have shown improved cardiac morbidity and mortality with the administration of perioperative β-blockers, concern for increased stroke risk and all-cause mortality has been noted. Current guidelines recommend that patients on chronic β-blocker therapy continue this perioperatively. In the setting of perioperative ACS, β-blocker therapy may decrease demand ischemia by improving oxygen supply and demand imbalance and is indicated in stable patients with ACS. The use of β-blockers in unstable patients or patients with acute cocaine intoxication should be cautioned.
Angiotensin-converting enzyme (ACE) inhibitor therapy should be considered in ACS after patients are stabilized. Angiotensin receptor blockers (ARBs) may be substituted in patients with HF with a left ventricular ejection fraction (LVEF) less than 40% or significant kidney dysfunction (creatinine >2.5 mg/dL for men or >2.0 mg/dL for women).
The optimum hemoglobin level in patients with perioperative ACS or MI is not known. Routine red blood cell transfusion in stable, nonbleeding patients may not be indicated when the hemoglobin is above 8 g/dL.
More aggressive interventional therapy with cardiac catheterization or fibrinolytics is dependent on the type of myocardial injury and risk of surgical bleeding. STEMI presents a high mortality rate if left untreated. In the nonsurgical setting, patient outcome is clearly related to time to reperfusion with a recommended “door to reperfusion time” of less than 90 minutes. The mainstays of reperfusion therapy include (1) cardiac catheterization and angioplasty or stent placement or (2) fibrinolytic therapy. Multiple studies have shown an improved survival rate, fewer bleeding complications, and reduced recurrent MI with catheterization and PCI. These interventions present significant concerns in the perioperative period because of an increased risk of bleeding.
Fibrinolytic therapy is often reserved for centers without PCI capabilities. It is recommended when symptom onset is less than 12 hours before presentation and PCI would not be available within 120 minutes. However, in the perioperative setting, fibrinolytics are almost universally contraindicated because of bleeding risk. PCI may be better suited for the treatment of perioperative STEMI. This is not without risk, however, because angioplasty or stent placement often requires DAPT and anticoagulation. Finally, emergent coronary artery bypass graft (CABG) surgery is an option, although this is associated with increased mortality rate when performed in the first 7 days after STEMI. Close consultation with cardiology and surgery is needed to weigh the risks and benefits of therapeutic options in perioperative STEMI patients.
Patients with NSTEMI may be managed more conservatively. However, in patients with a low cardiac output syndrome or arrhythmias, emergent PCI and reperfusion may be warranted. In stable NSTEMI patients, noninvasive studies may be the first approach. Again, close consultation with cardiology will aid in risk stratification and management.
Patients with significant chronic stable CAD also can present for noncardiac surgery. These patients may have either severe multivessel disease or left main CAD. Both portend an increased risk in the perioperative period. Significant left main disease or its equivalent is an indication for CABG. Occasionally, however, emergency noncardiac surgery may be needed before definitive CAD treatment. The risks and benefits of noncardiac surgery in these patients should be considered carefully in consultation with a cardiologist or cardiac surgeon.
Anesthetic management in these patients should be geared toward preventing, monitoring, and detecting myocardial ischemia. Careful monitoring of the ECG and hemodynamic status is important. Hemodynamic goals include a low-normal heart rate, normal to high BP, and normothermia. Left ventricular distention caused by fluid overload should be avoided because increased wall tension may increase myocardial oxygen demand and decrease myocardial perfusion. Additional monitoring may be considered, including perioperative TEE. Medications with more favorable hemodynamic profiles (e.g., etomidate) should be considered for anesthetic induction and maintenance. Pharmacologic therapy in the form of inotropic support may be needed. Mechanical support of the heart with an aortic balloon pump or axial flow devices may help maintain coronary perfusion in the setting of severe disease. Additional anesthetic considerations must be based on patient- and procedure-specific needs.
Hypertension
Hypertension is a common perioperative illness that has included roughly one third of all noncardiac surgery patients in the past. The new 2017 guidelines on hypertension define a normal BP as less than 120/80 mm Hg. Elevated BP is systolic BP between 120 and 129 mm Hg and diastolic BP less than 80 mm Hg. Stage I hypertension is now a systolic BP between 130 and 139 or diastolic BP between 80 and 89 mm Hg. Stage II hypertension is systolic BP greater than 140 and diastolic BP greater than 90 mm Hg. These new guidelines state that BP should be treated earlier to avoid complications, and with these new definitions, nearly half of the U.S. population will be considered to be hypertensive. Chronic hypertension is associated with an increased risk of stroke, heart disease, and renal failure.
Patients presenting on the day of surgery with high BP represent a clinical challenge. Safe systolic BP cutoffs for elective surgery are not well established. Uncontrolled hypertension is listed as a “minor” risk factor by the American College of Cardiology/American Heart Association (ACC/AHA), and it remains unclear if postponing surgery for uncontrolled hypertension improves patient outcome. Diastolic BP is better studied, with the preponderance of evidence suggesting safely proceeding with elective surgery if the diastolic BP is below 110 mm Hg. The relative risks and benefits of surgery in the setting of hypertension should be considered by the care team on a patient-by-patient basis.
Most preoperative antihypertensive medication can be continued in the perioperative period. Renin–angiotensin system blockers are associated with intraoperative hypotension and vasoplegia. Therefore many centers hold ACE inhibitors or ARBs for 24 hours before surgery, although this practice is controversial. A decrease in intraoperative hypotension is noted when these medications are held. On the other hand, failure to restart ACE inhibitor or ARBs has been associated with an increased 30-day mortality rate. The initiation of new medications immediately before surgery, such as β-blockade, may increase the risk of stroke or death. These medications should not be started preoperatively unless there is sufficient time for the patient to acclimate to the new medication before surgery. Patients taking β-blocker or sympatholytic agents should continue these medications perioperatively because acute withdrawal symptoms can occur if these agents are stopped.
Appropriate BP monitoring must be considered on a case-by-case basis with patient and surgical considerations in mind. Patients with chronic hypertension are at increased risk for hemodynamic lability. Anesthetic goals, therefore, include maintenance of hemodynamic stability within a range of BP. A reasonable goal is to maintain the BP within 20% of a patient’s baseline. In addition, blunting of the sympathetic response to anesthetic (laryngoscopy) and surgical stimuli should be attempted with anesthetic agents or adjunct medications. Relative hypotension can be treated with vasopressors with the goal of maintaining BP within a predefined range.
Severe hypertension must be managed expeditiously if end-organ complications are to be avoided (i.e., neurologic, cardiac, renal). First-line therapy with intravenous antihypertensive medications (e.g., calcium channel blocker, nitrates, β-blockers) is recommended. Postoperative complications related to elevated BP, such as surgical bleeding, must also be considered when determining the level of urgency in BP therapy.
Hypotension unresponsive to standard therapy may require further investigation. Surgical bleeding or manipulation of the vasculature may induce low BP and communication with the surgical team is vital. Myocardial ischemia or arrhythmias should be considered. Less common, but an important consideration, is the vasoplegic syndrome (VS), which is defined as severe hypotension refractory to catecholamine therapy without clear cause. The incidence of VS is highest in cardiac surgical patients, but it may be seen in noncardiac surgery as well. Exogenous vasopressin (dose of 1–2 units) may improve hypotension when conventional therapy has failed (i.e., decreasing anesthetic agent, volume expansion, and routine vasopressors). Alternatively, methylene blue (MB) is a well-described treatment. It is believed to interfere with the nitric oxide–cyclic guanylate monophosphate pathway, decreasing its vasorelaxant effect on smooth muscle. A bolus dose of 1 to 2 mg/kg over 10 to 20 minutes followed by an infusion of 0.25 mg/kg per hour for 48 to 72 hours is typical. Recently, the use of hydroxocobalamin (vitamin B 12a ; dose of 125–250 mg) has been recommended in the occasional complex patient who does not respond to the above treatments.
Heart Failure
Heart failure represents a significant perioperative complication presenting in up to 10% of patients after major noncardiac surgery. A preoperative history of HF may increase cardiac risk substantially, especially in the presence of risk factors such as CAD and diabetes. HF is broadly defined as a syndrome of impaired cardiac function and is often categorized into systolic failure associated with reduced ejection fraction (HFrEF) and diastolic failure with preserved ejection fraction (HFpEF).
Similar to perioperative ACS, care pathways for the perioperative management of patients with HF are ill defined and poorly studied. Retrospective cohort studies using data from large national databases have helped elucidate risk factors, but it remains unclear how specific therapies may affect outcomes in the perioperative period. Patients may present with dyspnea, orthopnea, tachypnea, or clinical signs such as crackles or decreased oxygen saturation. Signs of right-sided HF may also be present, including nausea and vomiting, lower extremity edema, and hepatic congestion. This may present a confusing clinical picture because many of the signs and symptoms of HF may be seen in the perioperative period because of other causes such as surgical insult, pain, and medication side effects.
Clinical suspicion of HF should prompt further investigation that includes an ECG, chest radiography, and cardiac biomarkers. Elevated brain natriuretic peptide (BNP) is supportive of the diagnosis of HF. Some patients with chronic HF may have a baseline abnormal level of BNP, and further elevation of BNP from baseline may be diagnostic of an acute exacerbation. Initial laboratory evaluation also should include electrolytes, renal and liver function tests, hemoglobin, and echocardiography.
Therapies may be tailored to specific causes. Treatment must be directed at managing concomitant respiratory failure; adequate oxygenation and ventilation are paramount to normalizing cardiac function. Electrolyte imbalances and acid-base disturbances should be corrected to minimize potential detrimental effects on ventricular contractility, pulmonary arterial pressure, and cardiac rhythm. Preload, contractility, and afterload must also be optimized.
In patients with signs of volume overload, diuretic therapy and fluid restriction are mainstays of therapy. Patients with HFrEF with clinical signs and symptoms of low cardiac output may benefit from inotropic therapy (e.g., dobutamine). In the setting of failed pharmacotherapy, mechanical devices may be used to treat severe HF (e.g., intraaortic balloon pump, ventricular assist devices).
In patients with stable hemodynamics, ACE inhibitor and β-blocker therapy is recommended by the ACC/AHA. Additionally, in patients with reduced ejection fractions, newer therapies such as combinations of valsartan and sacubitril (Entresto) are recommended to improve outcome. Readers are referred to the clinical guidelines from the ACC/AHA for more detailed information.
Takotsubo Cardiomyopathy
Approximately 2% to 3% of patients presenting with ACS meet diagnostic criteria for takotsubo cardiomyopathy (TCM). It is important to distinguish patients with TCM from those with ACS or HF because the etiology and treatment of each differ substantially.
Current data point towards a high level of circulating catecholamines as the predominant factor leading to TCM. Mammalian hearts have been found to have higher levels of β-adrenergic receptors in the apical ventricular myocardium. This phenomenon is believed to mediate an increased sensitivity to catecholamine surges in the apex of the heart. Clinically, the resultant myocardial dysfunction occurs disproportionately in the apex of the left ventricle, resulting in pathognomonic apical ballooning seen on echocardiography or ventriculography. Estrogen helps regulate the sympathetic response to catecholamines, blunting this response in reproductive years. This may explain why a predominance of TCM is seen in postmenopausal women.
Clinically, TCM often presents with a preceding physical or positive or negative emotional stressor (“happy heart syndrome” or “broken heart syndrome”). Certain diseases have been associated with TCM, including sepsis, pheochromocytoma, cerebral hemorrhage, respiratory failure, and thyrotoxicosis. Acutely, a hypertensive response to catecholamines may be noted followed by cardiomyopathy, hypotension, and HF.
Differentiating TCM from ACS is crucial. ECG findings play an important role, and abnormal findings are typically present. ST-segment elevation in lead aVR is found to have a high positive predictive value for TCM. In contrast, ST-segment depression in leads V 2 to V 4 makes ACS more likely. Non–ST segment elevation TCM is commonly associated with T-wave inversions in leads I, aVL, V 5 , and V 6 . However, NSTEMI is associated with ST-segment depression in V 2 and V 3 (anterior wall MI). Laboratory findings classically depict a mild elevation in cardiac biomarkers with TCM. The degree of wall motion abnormality is often disproportionately large compared with the degree of biomarker elevation in TCM. Echocardiogram findings often reveal circumferential wall motion abnormalities with the classic finding of apical ballooning occurring in 80% of cases. Other variants such as basal (see later) and midventricular types have been described. Regional wall motion abnormalities outside of a single coronary artery’s distribution can help distinguish TCM from acute MI. In addition, coronary angiography typically reveals nonobstructive or absent disease ( Box 2.2 ).
Box 2.2
