Stoelting Study 17 Cardio

Front 1

5. By what percent can a major coronary artery be stenosed in an asymptomatic patient?

Back 1

5. A major coronary artery can be stenosed by as much as 50% to 70% in an asymptomatic patient. (2

Front 2

6. What is the best indicator for a patient's cardiac reserve?

Back 2

6. The best indicator for a patient's cardiac r.serve is by evaluation of their exerCIse tolerance. A limited exercise tolerance in the absence of significant pulmonary disease gives evidence of a decrease in a patient's cardiac reserve. Alternatively, the cardiac reserve of a patient who is able to climb up two to three flights of stairs without stopping is probably adequate.

Front 3

7. When is angina pectoris considered "stable"?

Back 3

7. Angina pectoris is considered "stable" when there has been no change in the patient's anginal symptoms for at least 60 days. Factors related to the angina that stould be evaluated include the precipitating factors, frequency, and duration. (

Front 4

8. When is angina pectoris considered "unstable"? What is the clinical implication of unstable angina?

Back 4

8. Angina pectoris is cQ]sidered "unstable" when there has been a change in the patient's anginal symptoms. Changes that should be evaluated include the degree of activity a patient can do before the ons~t of angina and the duration of each anginal episode. Another symptom of unstable angina is chest pain occurring at rest. The clinical implication of unstable angina is that the patient may be at risk of an impending myocardial infarction.

Front 5

9. When dyspnea follows the onset of angina pectoris, what is it likely an indication of?

Back 5

9. Dyspnea after the onset of angina pectoris is likely an indication of acute left ventricular dysfunction due to myocardial ischemia and acute, transient cardiac failure

Front 6

10. How does angina pectoris due to spasm of the coronary arteries differ from classic angina pectoris?

Back 6

10. Angina pectoris due to spasm of tIe co:onary arteries differs from classic angina p~ctoris in that the pain may occur at rest but may not occur during periods of exerfun. Angina of this type is lSsociated with ST segment changes on the electrocardiogram. This type of angina is referred to as Prinzmernl's or variant angina.

Front 7

11. What is silent myocardial ischemia?

Back 7

11. Silent myocardial ischemia is my~cardia1 ischemia ilia occurs in the absence of angina This type of angina is ID)re rommon in patients with diabetes mellitus and carries the sane prognosis as myocardal ischemia associated ith angina.

Front 8

13. Is hypertension or tachycardia more likely to result in myocardial ischemia in the patient with coronary artery disease? What is the physiologic explanation for this?

Back 8

13. Tachycardia is more likely than hypertension to result in myocardial ischemia in the patient with coronary artery disease secondary to the greater strain on the heart associated with tach)cardia. Tachycardia results in an increased myocardial oxygen requimient in the prelellce of decreaS!d myocardial perfusion time. Myocardial rerfusiol on the left side of the heart, and thus myocardial oxygen sllpply, o~curs mostly during diastole. Hypertension, on the other hand, may lead to an increased myocardial oxygen requirement, but it may also lead to increased myocardial perfusion.

Front 9

16. What time period after surgery do most perioperative myocardial infarctions occur?

Back 9

16. Most perioperative myocardial infarctions occur in the first 48 to 72 hours postoperatively. ('

Front 10

18. What information can be gained from a preoperative electrocardiogram?

Back 10

18. Preoperative electrocardiograms may provide evidence of myocardial ischemia, prior myocardial infarction, cardiac hypertrophy, abnormal cardiac · rhythm or conduction disturbances, and electrolyte abnonnalities. (2

Front 11

19. How might myocardial ischemia appear on the electrocardiogram?

Back 11

19. Myocardial ischemia may appear as ST segment changes or T wave changes on an electrocardiogram. (

Front 12

22. What are some intraoperative goals for the anesthesiologist in an attempt to decrease therisk of myocardial ischemia in patients at risk?

Back 12

n. In an attempt to decrease the risk of a perioperative myocardial infarction in patients at risk the anesthesiologist should attempt to maintain stable patient hemodynamics. In general, the desired hemodynamics to minimize the risk of intraoperative ischemia include slower heart rates, lower filling presswes, and normal systolic blood pressures. A common recommendation for patients at risk of myocardial ischemia is that heart rate and blood pressure be maintained within 20% of awake values intraoperatively. Even so, approximately 50% of all new perioperative myocardial ischemic episodes are not preceded by or associated with changes in heart rate or blood pressure. l Nevertheless, the anesthesiologist may choose to closely monitor the patient's more limited hemodynamic status using invasive monitors to achieve these goals. He or she should also be prepared to intervene quickly with phannacologic interventions should they become necessary.

Front 13

23. What are two potential benefits of administering premedication preoperatively to patients with coronary artery disease?

Back 13

23. Two benefits of administering premedication preoperatively to patients with coronary artery disease are the decrease in the secretion of potentially harmful catecholamines and the potential to prevent the increase in myocardial oxygen requirements that may occur with tachycardia and hypertension related to anxiety

Front 14

24. How should anesthesia be induced in patients at risk for myocardial ischemia?

Back 14

24. The induction of anesthesia in patients at risk for myocardial ischemia is typically achieved with the administration of etomidate or the judicious administration of thiopental or propofol to minimize hemodynamic alterations associated with these drugs. Ketamine is not an appropriate choice for the induction of anesthesia in patients with coronary artery disease because of its potential to cause tact.ycardia and hypertension, which lead to increases in myocardial oxygen requirements.

Front 15

25. Why is there an increased risk of myocardial ischemia during direct laryngoscopy? What are some things th~ anesthesiologist may do during this time to minimize this risk?

Back 15

25. Direct laryngoscopy is associated with an increased risk of myocardial ischemia because i often produces intense sympathetic nervous system stimulation ffila oecause n Ollen IIoouce, Intense sympathetic nervous system stimulation be adequate levels of anesthesia to suppress synpathetic nervous system stimulation. Volatile anesthetics, intravenous anestlletics other than ketamine, opioids, and lidocaine may all be used to blunl the response to direct laryngoscopy. Alternatively, beta antagonilts may re :dminisered just before direct laryngoscopy to attenuate the increase in heart rate and blood pressure that can occur

Front 16

26. What are some methods of maintenance of anesthesia that may be employed by the anesthesiologist for the patient with cormary artery disease?

Back 16

26. The maintenance of mestresia for the patient with coronary artery disease may be achieved tIrrough the Idministration of volatile mesthetics and opioids in conjunction with nitrous oxide.

Front 17

27. What is coronary artery steal syndrome? What is its clinical significance?

Back 17

27. Coronarr artery steal syndrorre is a theoretical risk in which administration of a coronary ar.ery vasodilator to a patient with coronary artery disease could result in diversion of blood flow from the ischemic areas, in which stenotic coronary arteries are maJima1ly dlated, to areas in which the mronary arteries are patent and able to vasodilate. Isofiurane, of all the volatile anesthetics, is the most poten; coronary vasodilator. It is therefore believed that isoflurane is the volatile anesthetic that is most likely to result in this syndrome. Clinically, however, the administration of isofiurane to patients with coronary artery disease has not been shown to increase the risk of myocardial ischemia througr the coronary artery steal syndrome.

Front 18

30. How should neuromuscular blockade be reversed in patients with coronary artery disease?

Back 18

30. Neuromuscular blockade may be reversed in patients with coronary artery disease in the USul manner wiw. an anticholinesterase· anticholinergic drug combination. Glycopyrrolate has less of a chronotropic effect on the heart, but either glycopyrrolate or atropine is acceptable for the reversal of neuromuscular blockade.

Front 19

34. What are some treatment options when myocardial ischemia is detected intraoperatively?

Back 19

34. The detection of intraoperative myocardial ischemia should promptly lead to the treatment of any hemodynamic alterations in an attempt to increase myocardial oxygen supply while decreasing myocardial oxygen demand. Tachycardia may be treated with a beta-adrenergic antagonist. These drugs decrease the demand of the myocardium for oxygen through its effects of decreases in heart rate and myocardial contractility. Its administration should be judicious in patients with left ventricular dysfunction. Hypertension may be treated with a nitrate. Nitroglycerin may also be used in a situation in which there are ischemic changes on the electrocardiogram but blood pressure remains normal to high. Intravenous nitroglycerin administration may lead to reflex tachycardia. Hypotension may be treated with a sympathomimetic and intravascular fluids

Front 20

36. Why is it important to control postoperative pain in the patient with coronary artery disease?

Back 20

36. It is important to control. postoperative pain in the patient with coronary artery disease because pain can increase myocardial oxygen requirements. Pain is oftm accomfanied by tachycardia and hypertension as a result of sympathetic nervous system discharge. These can be detrimental to the pa.1ient with coronary artery disease