PREOPERATIVE EVALUATION in the ELDERLY Module 2 CARDIAC ASSESSMENT

1. PREOPERATIVE EVALUATION in the ELDERLYModule 2CARDIAC ASSESSMENT Ed Vandenberg, MD, CMD Geriatric Section OVAMC & Section of Geriatrics 981320 UNMC Omaha, NE 68198-1320 evandenb@unmc.edu Web: geriatrics.unmc.edu

2. OBJECTIVES: Upon completion the Learner will be able to: • List the key tasks in a preoperative cardiac evaluation • List cardiac the cardiac risk factors, functional capacity assessment and surgical procedure risk for a preoperative evaluation. • Describe pre-op evaluationcardiac evaluation.

3. EXPLANATION of PROCESS Step one: You will leave this PowerPoint and enter the module at the web-based address below. After module is entered, review the summary card on the left hand side of page. It will enlarge by clicking on it. Step two: after familiarizing yourself with the card, start the explanation of the cards content by clicking on the underlined items and a full explanation will appear on the right hand side. Step three: Review this material by scrolling downward. When the right hand scroll down is completed, click on the next underlined item to work through the summary card. Step four: After completing the last slide, to complete the question for credit for this module, please close out that module, and advance to the question 2 in Blackboard,(see next slide), then answer the question and review the answer. Then, when read, proceed to module #3 where we will complete our work on cardiac evaluation. Now link to this website for completion of step 1-3. http://webmedia.unmc.edu/intmed/geriatrics/reynolds/pearlcards/preop/preoppearlcard.htm

4. Post-test • A 76-year-old woman who resides in an assisted-living apartment is admitted to the hospital for right femoropopliteal bypass surgery. She has experienced increasing claudication pain, which has confined her to a wheelchair. Preoperative evaluation, including review of history, examination, and preoperative testing, reveal the following: the patient had an uncomplicated inferior wall myocardial infarction 1 year ago; she has osteoarthritic changes of both knees; she is a well-controlled, insulin-dependent diabetic; her blood urea nitrogen level is 56 mg/dL and serum creatinine is 1.4 mg/dL. Her electrocardiogram shows normal sinus rhythm with Q waves in leads II, III, and a VF. Hydrate and proceed with surgery. Order radionuclide angiography. Order transthoracic echocardiography. Order an exercise stress test. Order dipyridamole-thallium imaging. Which of the following is the next correct step?

5. Which of the following is the next correct step? • Hydrate and proceed with surgery. • Order radionuclide angiography. • Order transthoracic echocardiography. • Order an exercise stress test. • Order dipyridamole-thallium imaging.

6. Answer: E. Order dipyridamole-thallium imaging. • The goal of the preoperative clinical evaluation is to establish and minimize the perioperative risk of the patient. This patient scores 15 points on the Modified Cardiac Risk Index (based on age > 70 years; myocardial infarction > 6 months earlier; poor general medical status given the elevated blood urea nitrogen) and would be assigned a class I risk. However, she has three low-risk variables: age > 70 years, diabetes mellitus, and Q waves on electrocardiogram. These factors increase her to intermediate-risk status (3% to 15%) for a perioperative cardiac event. As the patient is scheduled to undergo vascular surgery, it may be advisable to delay surgery to further evaluate her potential for cardiac complications in the perioperative period. Hydration, without evidence of decreased volume status, is not indicated and may increase the patient?s risk for perioperative congestive heart failure. Used with permission from: Murphy JB, et. al. Case Based Geriatrics Review: 500 Questions and Critiques from the Geriatric Review Syllabus. AGS 2002 New York, NY.

7. Neither radionuclide angiography nor transthoracic echocardiography is recommended to determine perioperative risk. Radionuclide angiography is used to assess left ventricular function. Studies of radionuclide angiography in predicting perioperative cardiac complications have found poor predictive negative test results when patients with normal left ventricular ejection fraction are evaluated, and poor predictive positive test results when patients with low left ventricular ejection fraction are evaluated. Likewise, transthoracic echocardiography adds little to the clinical evaluation in determining risk of cardiovascular complications.

8. Exercise stress testing is commonly used to screen for coronary artery disease because of its low cost and wide availability. Unfortunately, patient-related problems may limit its utility. A patient with degenerative joint disease, peripheral vascular disease, previous stroke, or other mechanical disability may have difficulty in exercising to meet her target heart rate. Because of these limitations, exercise stress testing has a poor predictive value and is not recommended in these patients for determining perioperative risk.

9. Studies of dipyridamole thallium imaging have demonstrated its utility in determining the potential for cardiac complications in intermediate-risk patients, such as the patient in this case. A posttest probability of 1% for cardiac complications is associated with a negative dipyridamole thallium scan, and the risk for complications rises to 23% with a positive scan. Dobutamine stress echocardiography is also effective in determining the level of risk in patients with a low score on the Modified Cardiac Risk Index but one or more low-risk variables. Patients with a normal dobutamine stress echocardiography study are at very low risk for cardiac complications during vascular surgery, but their risk climbs dramatically with an abnormal study.

10. Patients with normal findings on dipyridamole thallium imaging or dobutamine stress echocardiography can proceed with the vascular surgery. Those with abnormal studies may need to have the nature of their high-risk state determined. Those with modifiable risk factors (congestive heart failure, arrhythmia) should have their medical status optimized prior to surgery. If factors are not modifiable and surgery is essential, more intensive perioperative monitoring may be required. In patients with a high-risk state due to ischemic heart disease, the need and timing of coronary revascularization must be determined. While dipyridamole thallium testing allows the determination of risk and closer monitoring in the perioperative period, further research is needed to determine whether this results in improved clinical outcomes. End