Case Files Surgery, (LANGE Case Files) 4th Ed.

SECTION II. Clinical Cases

CASE 38

A 72-year-old man undergoes evaluation for the treatment of an 8-cm abdominal aortic aneurysm (AAA). His past medical history is significant for unstable angina that was treated by coronary artery angioplasty and stenting 8 months ago. Since that time, he has been doing well without angina. His other medical problems include hypertension and gout. His medications are metoprolol, allopurinol, and aspirin. Recently, he has been active and walks 1 mile daily. He had a 60-pack-year smoking history but quit 8 months ago, and he consumes alcohol socially. He denies any nocturnal dyspnea or pulmonary symptoms. On physical examination, he appears well nourished. His blood pressure is 138/82 mm Hg, and his heart rate is 66 beats/min. There is no jugular venous distension or carotid bruits. The lungs are clear bilaterally, and the heart sounds are normal. A nontender, pulsatile mass is present in the abdomen. No cyanosis or edema is noted in the extremities. Laboratory evaluations reveal a normal complete blood count and normal electrolyte levels. The serum urea nitrogen and serum creatinine levels are 40/1.4 mg/dL. The urinalysis reveals trace proteinuria. The electrocardiogram (ECG) reveals a normal sinus rhythm and left ventricular hypertrophy. The CT angiography confirms the presence of an infrarenal AAA that is anatomically unfavorable to endovascular repair.

Images What are the risks associated with surgical treatment of this patient’s problem?

Images What can be done to optimize the patient’s condition?

ANSWERS TO CASE 38: Preoperative Risk Assessment and Optimization

Summary: A 72-year-old man with a large AAA, hypertension, coronary artery disease, gout, and mild chronic renal insufficiency. His aneurysm appears to be anatomically not amendable to endovascular repair. Give his medical risk factors, this patient requires risk assessment, stratification, and optimization prior to undergoing open AAA repair.

• Surgical risk factors: The risks include the usual procedural risks and postoperative pulmonary, renal, and cardiac complications.

• Optimizing the status of the patient: A complete cardiac risk assessment should be made to define the current cardiac status and identify and quantify any end-organ dysfunction caused by hypertensive and cardiac disease. Optimization of patient status can include pharmacologic therapy, coronary revascularization, and perioperative hemodynamic monitoring.

ANALYSIS

Objectives

1. Learn the general approach to preoperative cardiac risk assessment.

2. Learn the principles of optimization of the medical problems of surgical patients.

Considerations

The goals of preoperative patient evaluation are to prevent perioperative complications, avoid unnecessary delays in surgical therapy, avoid unnecessary risks to patients from testing procedures, and implement long-term management plans for patients with medical problems that are inadequately treated. Elective open repair of AAAs is associated with a postoperative mortality rate of 2% to 6%, with cardiac and renal complications the most common causes of death. This patient has a history of coronary artery disease and hypertension and subtle evidence of chronic renal insufficiency (proteinuria). It is vital to assess his cardiac and renal status thoroughly prior to surgery. A favorable factor in the history is that his cardiac symptoms have resolved since the coronary artery stent placement. The risk of perioperative cardiac death or myocardial infarction is extremely low when a patient has completed surgical coronary revascularization within 5 years or has undergone coronary angioplasty from 6 months to 5 years prior, and if the clinical status of the patient has remained stable without recurrent symptoms of ischemia. Further formal cardiac evaluation may not be required in this setting.

For this patient, the cardiac evaluation begins with a complete history, a physical examination, and direct communication with the patient’s cardiologist or primary physician. Other important issues are the adequacy of the hypertension control and the quantification of the renal insufficiency. If not obtained previously, a 24-hour urine collection to determine creatinine clearance may be helpful because the serum creatinine level in an elderly patient may not accurately reflect renal clearance functions because of the smaller muscle mass. This information may prove useful in the perioperative period for dose adjustment of medications. Control of systolic hypertension reduces perioperative cardiac complications, and this should be accomplished prior to any elective surgery. Based on the revised cardiac risk index (RCRI), this patient has moderate cardiac risk with a score of 3 (age, coronary artery disease, and major surgery). Patients with moderate cardiac risks have reduced cardiac complications when adequate β-blockade is established during the perioperative period; therefore, if this patient had not been taking a β-blocker (metoprolol), one would have been prescribed and titrated to effect preoperatively. Recent evidence suggests that high-risk vascular surgery patients may also benefit from perioperative use of statins; therefore strong considerations for perioperative statins therapy should be given. Further preparations during the perioperative period include preoperative hydration to prevent hypotension during anesthesia induction, monitoring of blood pressure by an arterial line, monitoring of intravascular volume status by central venous pressure measurement, and possibly the monitoring of cardiac status by a pulmonary artery catheter or transesophageal echocardiography.

In general, the guiding principle for the majority of asymptomatic patients with cardiac risks or cardiac disease is optimization of medical comorbidities and the initiation of pharmacologic prophylaxis in patients with high-risk profiles. When considering additional testing or interventions for patients in the perioperative setting, it is vital to consider the risk-benefit ratio of the tests and interventions.

APPROACH TO: Preoperative Assessment of High-Risk Patients

DEFINITIONS

REVISED CARDIAC RISK INDEX (RCRI): Patients are stratified into class 1-4 based on a six-point scoring system that helps stratify the risk for perioperative cardiac morbidity in elective surgery patients. The six points are: (1) ischemic heart disease, (2) congestive heart failure (CHF), (3) cerebral vascular disease, (4) high-risk surgery (abdominal, thoracic, vascular, major orthopedic procedures), (5) insulin-dependent diabetes, and (6) serum creatinine more than 2 mg/dL. Perioperative β-blockade appears to significantly reduce cardiac morbidity in moderate- and high-risk patients with two or more points (Class III or IV) (Table 38–1).

Table 38–1 • REVISED CARDIAC RISK INDEX

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METABOLIC (MET) DEMAND: An arbitrary measure of the aerobic demands of specific activities. The perioperative cardiac and long-term risks are increased for patients unable to meet a 4 MET demand during most of their daily living (eg, activities of daily living such as dressing and cooking require 1-4 MET; climbing a flight of stairs, walking at 6 mph, and scrubbing the floor require 4-10 MET).

RESTING LEFT VENTRICULAR FUNCTION: Generally assessed by echocardiography. A patient with a left ventricular ejection fraction (LVEF) of less than 35% has a significantly increased risk of perioperative cardiac complications; however, a LVEF greater than 35% does not reliably rule out the development of cardiac complications.

DOBUTAMINE STRESS ECHOCARDIOGRAPHY: Provocative testing under a controlled setting involves the administration of high-dose intravenous dobutamine to evaluate the cardiac status of patients who are unable to undergo an exercise stress test. Test results are positive when the patient develops symptoms and/or wall motion abnormalities as revealed by echocardiography. Vascular surgery patients with positive test results have a 7% to 23% risk for a perioperative myocardial infarction (MI) (high false-positive rate/low specificity). A dobutamine stress test with negative results is associated with a 0% to 7% risk of perioperative MI (low false-negative rate/high sensitivity).

CLINICAL APPROACH

When preparing a patient with significant medical conditions for elective surgery, the patient’s comorbidity problems must be clearly defined and addressed during the perioperative period. An assessment of comorbidity has been found to be particularly important for patients undergoing vascular surgery procedures. Advanced vascular disease is frequently associated with long-standing diabetes, atherosclerosis, and hypertension, and these factors may cause multiple end-organ damage and reduce the patient’s physiologic reserve. The assessment of cardiac risk consists of the eight steps listed in Table 38–2. Several major, intermediate, and minor clinical predictors can be used to determine patient risks (Table 38–3). Clinical history, the patient’s current symptoms, and the level of physical activity are important in determining the patient’s risk. Notably, in vascular surgery patients, coronary artery disease may be clinically silent because of limited activity and/or coexisting diabetes mellitus. The other major component in risk assessment is stratification of the cardiac risk associated with the proposed operative procedure. The combination of patient risk and procedural risk is used to determine if additional testing, pharmacological intervention, coronary intervention, or perioperative monitoring is indicated.

Table 38–2 • CONSIDERATIONS IN PREOPERATIVE CARDIAC RISK ASSESSMENT

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Table 38–3 • CLINICAL PREDICTORS OF CARDIAC RISK

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Additional cardiac evaluation ranges from noninvasive tests such as 24-hour Holter monitoring, echocardiography, exercise stress testing, pharmacologic stress testing, and invasive examinations such as cardiac catheterization. Generally, patients with moderate clinical risks who are to undergo moderate- to high-risk procedures may benefit from noninvasive stress testing. The role of prophylactic coronary revascularization for high-risk vascular surgery patients has been addressed in a randomized controlled trial, and the results did not demonstrate short- or long-term advantages to revascularization; in addition, patients undergoing preoperative coronary revascularization had significant delays in receiving their intended therapies.

Based on the results of randomized controlled clinical trials, perioperative β-blockade is clearly beneficial in reducing perioperative cardiac morbidity and mortality in a population of vascular surgery patients with inducible ischemic cardiac disease. The liberal application of perioperative β-blockade could potentially cause hypotension, cerebral ischemia, and increase the risk for ischemic strokes; therefore, patients placed on prophylactic β-blockers need to be assessed and monitored for treatment-induced hypotension and bradycardia.

COMPREHENSION QUESTIONS

38.1 A 63-year-old man desires elective repair of an asymptomatic inguinal hernia because it interferes with his golf game. He has a history of hypertension controlled with an angiotensin-converting enzyme inhibitor and suffered an MI 4 years ago. He underwent coronary artery bypass 4 years ago and has been asymptomatic since that time. Which of the following is the most appropriate preoperative plan?

A. Review of the history, physical examination, ECG, and routine laboratory tests prior to surgery.

B. Review of the history, physical examination, ECG, laboratory tests, and a stress test prior to surgery.

C. Review of the history, physical examination, ECG, laboratory tests, and coronary angiography to document the patency of bypass grafts.

D. Review of the history, physical examination, ECG, laboratory tests, and ventilation/perfusion (V/Q) scan prior to surgery.

E. Given his cardiac history, the patient has prohibitive risks for the development of perioperative cardiac complications. Elective surgery is contra-indicated.

38.2 A 55-year-old patient with a history of unstable angina presents with acute abdominal pain. He is found to have diffuse peritonitis, tachycardia, and chest pain. The ECG shows ischemic changes in the anterior leads. An upright chest radiograph reveals a pneumoperitoneum. Based on these findings, a perforated peptic ulcer is suspected. Which of the following is the most appropriate treatment?

A. Antibiotics therapy and immediate cardiac catheterization.

B. Antibiotics therapy and nonoperative care.

C. Antibiotics therapy, invasive monitoring, maximal treatment for his cardiac disease, and surgery when he is stabilized in 48 hours.

D. Antibiotics therapy, invasive monitoring, and early surgical intervention.

E. This patient has overwhelming cardiac risks; therefore medication to keep him comfortable is the most appropriate approach.

38.3 A 46-year-old man is being considered for surgery for a very symptomatic hernia. He has intermittent chest pain, and, because of an ankle injury, he is unable to perform optimal stress testing. Dobutamine echocardiography is ordered. Which of the following is most accurate of dobutamine echocardiography?

A. It is highly specific in identifying patients who will develop perioperative cardiac complications.

B. It is highly sensitive in identifying patients who will develop perioperative complications.

C. When positive, it reliably predicts the occurrence of perioperative complications.

D. It is of limited use in patients with moderate clinical risk who have poor functional capacity and are undergoing high-risk procedures.

E. It is rarely indicated as a preoperative assessment tool.

38.4 Which of the following statements regarding perioperative cardiac risk assessment and risk modification is most accurate?

A. Preoperative coronary artery revascularization is beneficial in preventing perioperative cardiac complications in patients with “silent” coronary artery disease.

B. β-Blocker application during the perioperative period should be applied for all elective surgery patients older than 60.

C. Coronary angiography is an evaluation tool that should be applied liberally to identify asymptomatic patients who might be at risk for the development of perioperative cardiac complications.

D. Preoperative cardiac risk assessment results in much unnecessary testing and harm.

E. Perioperative cardiac risk assessment should lead to risk modification during and beyond the perioperative period.

38.5 A 66-year-old man with a history of symptomatic reducible left inguinal hernia is undergoing evaluation for elective hernia repair. He has a history of hypertension and elevated total cholesterol level with unfavorable LDL-HDL ratio (low- to high-density lipoprotein ratio). He denies any history of chest pain or shortness of breath associated with exertion. His blood pressure in the office is 150/90 mm Hg. Which of the following is the best next step?

A. Refer patient for exercise stress test.

B. Place patient on a β-blocker for 1 week prior to scheduling his hernia repair.

C. Discuss with patient regarding long-term cardiac risk-reduction benefits and work with the patient’s primary care physician to help improve these risk factors.

D. Place patient on a β-blocker for 1 week and then schedule the patient for an elective hernia repair under local anesthesia.

E. Refer the patient for coronary angiography and revascularization as indicated.

ANSWERS

38.1 A. History, physical examination, laboratory tests, and an ECG are sufficient evaluation for this patient who underwent surgical revascularization of the coronary vessels 4 years ago and has had no recurrence of symptoms. Excessive invasive testing in this patient is not indicated. The history and current physical status suggest that the patient is an appropriate candidate for elective hernia operation.

38.2 D. A perforated ulcer is a surgical emergency. Early supportive care, invasive monitoring, and operative therapy are indicated for this patient with intraabdominal sepsis and evolving cardiac ischemia that is likely aggravated by his chemical peritonitis and septic process.

38.3 B. Dobutamine echocardiography has a sensitivity of 93% to 100% in identifying patients with coronary artery disease (ie, false-negative results are rare), but perioperative MI is seen in only 7% to 23% of patients with positive stress test results (low specificity).

38.4 E. Evaluation and preparation of a patient for elective surgery not only offers an opportunity to assess a person’s fitness for surgery but also is an opportunity to identify risk factors that may affect the person’s longevity and quality of life subsequent to the operation. Perioperative β-blocker use has been shown to reduce cardiac morbidity and mortality among individuals with RCRI scores greater than 3, and the application of this strategy in patients with lower risks may be associated with increased morbidity related to medication side effects that may include cerebral ischemia. Aggressive pursuit of silent coronary artery disease preoperatively is not indicated for most patients, because routine preoperative revascularization of asymptomatic patients has not been demonstrated to reduce perioperative cardiac morbidity and mortality, or improve longevity of patients.

38.5 C. Counseling and modification of cardiac risk factors including more optimal control of hypertension is important for this patient. The preoperative setting is a great opportunity to perform a comprehensive review of risk factors and initiate long-term cardiac risk-reduction strategies. There is very little role for prophylactic coronary revascularization, especially in a patient who is asymptomatic with risk factors that are inadequately addressed.

CLINICAL PEARLS

Images Most body surface operations (eg, hernia repair, breast surgery) can be safely completed with minimal physiologic stress to patients.

Images Perioperative β-blockade has been shown to reduce cardiac morbidity in high-risk patients; at the same time, this intervention has also been shown to produce complications including bradycardia, hypotension, and cardiac arrests; therefore this therapy should be applied toward moderate- and high-risk patients.

Images Perioperative cardiac risk is low when patients have completed surgical coronary revascularization within 5 years or have undergone coronary angioplasty from 6 months to 5 years prior and have no symptoms of ischemia.

Images The benefits of obtaining a thorough history and physical examination and adjusting medications prior to any planned elective procedures should never be overlooked.

REFERENCES

Brett AS. Coronary assessment before noncardiac surgery: current strategies are flawed. Circulation. 2008;117:3145-3151.

Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation. 2002;105:1257-1267.

Poise Study Group. Effects of extended-release metoprolol succinate in patients undergoing noncardiac surgery (POISE trial): a randomized controlled trial. Lancet. 2008;371(9627):1839-1847.

Schanzer A, Hevelone N, Owens CD, et al. Statins are independently associated with reduced mortality in patients undergoing infrainguinal bypass graft surgery for critical limb ischemia. J Vasc Surg. 2008;47:774-781.