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 Risk Stratification and Risk Factors

Bruce S. Cutler, M.D., William C. Mackey, M.D.

Includes:

  • Cardiac Risk Evaluation
  • Pulmonary Risk Evaluation
  • Atherosclerotic Risk Factor Assessment
  • Lipid Disorder Evaluation and Management

I. Cardiac Disease

1. Recognize the frequent association of coronary artery and peripheral vascular disease.

2. Understand the risk factors predictiveof perioperative myocardial infarction or cardiac death.

3. Be able to quote basic statistics regarding the frequency of severe CAD in patients with symptomatic peripheral vascular disease.

4. Be familiar with the early and late cardiac mortality figures following major vascular surgery.

II. Anatomy and Pathophysiology

1. Describe normal coronary artery anatomy

2. Understand the clinical significance of chronic stable angina, unstable angina, recent and remote myocardial infarction and congestive heart failure

3. Understand how an imbalance of myocardial oxygen supply and demand may lead to myocardial ischemia

4. Describe those factors that may lead to an increased demand for myocardial oxygen, and/or a decreased supply that will contribute to myocardial ischemia.

5. Understand the clinical and histological difference between a subendocardial and transmural infarction.

6. Understand the effects of general and regional anesthesia on myocardial oxygen demand and myocardial ischemia.

7. Understand the most important factors present intraoperatively and in the post-operative period that contribute to myocardial ischemia.

III. Diagnosis

1. Understand the signs and symptoms of chronic stable angina, unstable angina, myocardial infarction and congestive heart failure.

2. Know the risks of operation in a patient with a recent myocardial infarction, unstable angina, or poorly compensated congestive heart failure.

3. Be familiar with the currently used methods for screening for coronary artery disease, and their limitations. ( e.g . Dipyridamole thallium scanning, Exercise testing, Dobutamine stress echo, ambulatory Holter monitoring)

4. Know which patients should undergo a preoperative test for coronary artery disease

5. Know how to interpret the results of thallium scans

6. Know what further evaluation a patient with a positive study should have.

7. Know which patients should have coronary angiography prior to vascular surgery.

8. Understand that the magnitude of the operation should be tailored to the severity of the patients cardiac risk. Know when to employ an extra anatomic, or limited procedure instead of an intra-abdominal operation.

9. Understand when, during the course of a vascular operation and subsequent recovery, a patient is most likely to suffer a myocardial infarction

IV. Treatment

1. Recognize that most patients with even severe CAD can survive a major vascular operation, but they should have close postoperative cardiology follow up and subsequent consideration for coronary revascularization for the best long term survival.

2. Know when CABG may be indicated to correct severe CAD prior to peripheral vascular surgery.

3. Understand the indications for a combined CABG and CEA or AAA operation.

4. Understand the reasons for controlling myocardial ischemia intraoperatively , and during recovery from a major vascular operation

5. Know how to detect and treat myocardial ischemia postoperatively

6. Know how to diagnose and treat common complications of myocardial infarction.

Pulmonary Disease

I. Introduction

1. Recognize that many of the same risk factors that accelerate the development of peripheral vascular disease, also cause the development of chronic obstructive pulmonary disease (COPD)

2. Understand that long operations, intra-abdominal and thoracic incisions, and poor left ventricular function increase the risk of pulmonary complications even in the absence of underlying COPD.

3. Understand that cardiac and other co-morbid conditions are more important in determining postoperative pulmonary complications than pre-existing pulmonary disease

II. Diagnosis

1. Know the risk factors for pulmonary disease, including: history of tobacco use, chest wall deformities, industrial dust exposure, previous pulmonary resection, dyspnea on mild exertion, pulmonary hypertension, recurrent respiratory tract infections, bronchospasm , obesity, advanced age and hypercapnia or hypoxia at rest.

2. Understand the signs and symptoms of COPD.

3. Know what to look for in the physical examination of a patient with suspected pulmonary insufficiency

4. Understand that clinical assessment is at least as accurate as routine preoperative pulmonary function tests in predicting which patients will have a postoperative pulmonary complication.

5. Understand that the primary benefit of preoperative pulmonary function studies is to make the diagnosis of pulmonary disease and as an aid in choosing between treatment alternatives.

6. Understand that there is no pulmonary function test, or index that can accurately predict that a patient will need prolonged postoperative mechanical ventilation.

7. Understand that general anesthesia interferes with pulmonary gas exchange and pulmonary defense mechanisms, particularly the mucociliary transport mechanism.

8. Know how to interpret the results of pulmonary function tests, and know which patients might benefit from the perioperative use of bronchodilators, antibiotics, inhalers etc.

9. Know which patients might benefit from a preoperative pulmonary or anesthesia consultation to help with the operative and postoperative management of a patient with known pulmonary insufficiency

III. Treatment

1. Understand how to reduce the pulmonary risk of a vascular operation by the choice of operation and anesthesia.

2. Understand which pulmonary conditions may benefit from the perioperative use of steroids, bronchodilators, antibiotics and inhalers

3. Understand the causes and treatment of the adult respiratory distress syndrome (ARDS)

References

Cardiac Disease

1. Mackey WC, O'Donnell TF, Callow AD. Cardiac risk in patients undergoing carotid endarterectomy : Impact on perioperative and long-term mortality, J Vasc Surg 11:226-34; 1990.

2. Perry MO, Calcagno D. Abdominal aortic aneurysm surgery: The basic evaluation of cardiac risk. Ann Surg 208:738-741 ;1988 .

3. Cooperman M, Pflug B, Martin EW, Evans WE. Cardiovascular Risk Factors in patients with peripheral vascular disease. Surgery; 84:505-9 ;1978 .

4. Hertzer NR, Beven EG, Young JR, et al. Coronary artery disease in peripheral vascular patients: A classification of 1000 coronary angiograms and results of surgical management. Ann Surg 199:223-33 ;1984 .

5. Goldman L. Cardiac risks and complications of noncardiac surgery. Ann Intern Med 98:504-13 ;1983 .

6. Boucher CA, Brewster DC, Darling RC, Okada RD , Strauss HW, Pohost GM. Determination of Cardiac risk by dipyridamole thallium imaging before peripheral vascular surgery. NEJM 312:389-94; 1985.

7. Eagle KA, Singer DE, Brewster DC, Darling RC, Mulley AG, Boucher CA. Dipyridamole thallium scanning in patients undergoing vascular surgery: Optimizing preoperative evaluation of cardiac risk. JAMA 257:2185-9 ;1987 .

8. Mangano DT, Goldman L. Preoperative assessment of patients with known or suspected coronary disease. NEJM 333:1750-56 ;1995 .

9. Lachapelle K, Graham, AM , Symes JF. Does the clinical evaluation of the cardiac status predict outcome in patients with abdominal aortic aneurysms? J Vasc Surg 25:964-71 ;1992 .

10. Arous EJ, Baum PL , Cutler BS. The ischemic exercise test in patients with peripheral vascular disease. Arch Surg 119:780-3 ;1984 .

11. Poldermans D, Fioretti PM, Forster T, Thomson IR, et al. Dobutamine Stress Echocardiography for Assessment of peroperatrive cardiac risk in patients undergoing major vascular surgery. Circulation 87:1506-12 ;1993 .

12. Raby KE, Goldman L, Creager MA, Cooke JP, Hlatkey MA. The role of coronary angiography and coronary revascularization before noncardiac vascular surgery. JAMA 273:1919-25:1995.

13. Seeger JM, Rosenthal GR, Self SB, Flynn TC, Limacher MC, Harward TRS. Does routine stress-thallium cardiac scanning reduce postoperative cardiac complications? Ann Surg 219:654-63 ;1994 .

14. Cronnenwett JL, Murphy TF, Selkenock GB, Whitehouse WM, Lindenauer SM, Graham LM, Quint LZE, Silver TM, Stanley JC. Actuarial analysis of variables associated with the rupture of small aortic aneurysms. Surgery 98:472-83 ;1985 .

15. Cutler BS, Hendel RC, Leppo JC. Dipyridamole thallium scintigraphy predicts perioperative and long-term survival after major vascular surgery. J Vasc Surg 15:972 ;1992 .

16. Massie, MT, Rohrer, MJ, Leppo JA, Cutler BS. Is coronary angiography necessary for vascular surgery patients with a positive dipyridamole thallium scan? J Vasc Surg . In press.

17. Kazmers A. Cardiac Risk Assessment Before Vascular surgery. Futura Publishing Co. Armonk NT 1994.

Pulmonary

1. Bartlett RH, Pulmonary Insufficiency. Chapter in Wilmore DW, Brennan MF, Harken AH, et all ( eds ): Care of the Surgical Patient, New York . Scientific American 1989.

2. Lawrence VA , Page CP, Harris GD: Preoperative spirometry before abdominal operations. A critical appraisal of its predictive value. Arch Intern Med 149:280 ;1989 .

3. Gennaro MT, Preoperative Evaluation of Pulmonary Function. Validity, Indications and Benefits .. Am Rev Resp Dis 119:293-310 ;1970 .

4. Arabian AA, Spagnolo SV, Prashant KR. Evaluation and Therapy of Pulmonary Problems in Surgical Patients. Clinical Notes Resp Dis 21:3-14 ;1982 .

5. Jayr C, Matthay MA, Goldstone J, Gold WM, Wiener- Kronish JP. Preoperative and Intraoperative Factors Associated with Prolonged Mechanical Ventilation. A study in patients following major abdominal vascular surgery. Chest 103:1231-1236.

6. Williams-Russo P, Charson ME, MacKenzie CR, Gold JP, Shires TG. Predicting Postoperative Pulmonary Complications. Is it a real problem? Arch Intern Med 152:1209-1213 ;1992 .

7. Spivack SD, Shinozaki T, Albertini JJ, Deane R. Preoperative Predication of Postoperative Respiratory Outcome. Coronary artery bypass grafting. Chest 109:1222-30 ;1996 .

8. Zibrak JD, O'Donnell CR, Marton K. Indications for Pulmonary Function Testing. Ann Intern Med 112:763-771 ;1990 .

9. Zibrak JD, O'Donnell CR, Marton , KI et al. Preoperative Pulmonary Function Testing. A Position Paper of the American College of Physicians. Ann Intern Med 112:793-794 ;1990 .

Posted June 2010