Acute ST-Segment Elevation Myocardial Infarction

Chapter 21 Acute ST-Segment Elevation Myocardial Infarction




Clinical Case Problem 1: A 60-Year-Old Male with Acute Chest Pain


A 60-year-old farmer is brought to the local emergency department with his wife by the county sheriff. Apparently he developed a “twinge of chest pain” while shoveling grain 3 hours ago. He insisted on staying home until “he collapsed on the floor.” Even then, he wanted to stay home and rest, but his wife insisted on calling 911. The call was answered by the sheriff’s department, and a county sheriff rushed him and his wife to the emergency department at the nearest hospital in the rural area in which he resides. At his admission, he states that the pain is “almost gone   .   .   .   what a fuss about nothing.” On taking of the history, he tells the admitting physician that he smokes two packs of cigarettes daily, that he drinks a “goodly amount of beer,” and that he had been told that his serum cholesterol level is good; the doctor even told him his was one of the best values he had ever seen for a man his size and age. On further questioning, he admits to a dull, aching, viselike pain around his chest, with radiation to the left shoulder. He also discloses that when the pain was at its worst, he experienced nausea and vomiting; but he adds that because he is already doing better, it must have been something he ate. His wife adds that she has never seen him in so much pain, but he is a “stubborn old goat.”


He still insists that it is just a little stomach trouble, but on physical examination, he is sweating and diaphoretic. He has vomited twice since coming to the emergency department. His blood pressure is 160/100   mm Hg, and his pulse is 120 and irregular. His abdomen is obese, and you believe you can detect an enlarged aorta by deep palpation.


His electrocardiogram (ECG) reveals significant Q waves in V1 to V4, with significant ST-segment elevation in the same leads. There are reciprocal ST changes (ST-segment depression) in the inferior leads (II, III, and aVF).



Select the best answer to the following questions




1. The most likely diagnosis in this patient is


a. acute inferior wall myocardial infarction (MI)

b. acute anterior wall MI

c. acute myocardial ischemia

d. acute pericarditis

e. musculoskeletal chest wall pain

2. Given the history, physical examination, and ECG, your first priority is to


a. call the ambulance for immediate transport to another hospital that “knows how to treat this thing”

b. admit the patient for observation

c. administer streptokinase or tissue plasminogen activator (t-PA) intravenously (IV)

d. administer heparin IV

e. none of the above

3. The nearest big-city hospital is a 6-hour drive. Given your attention to your first priority, you would now


a. call the ambulance for immediate transport to another hospital that “knows how to look after this thing”

b. admit the patient to the coronary care unit for observation

c. administer streptokinase or alteplase IV immediately

d. administer heparin IV immediately

e. none of the above

4. Which of the following criteria should be met before a patient is given thrombolytic therapy following the history, physical examination, and ECG previously described?


a. typical chest pain suggestive of MI

b. ECG changes confirming MI

c. the absence of other diseases that would explain the symptoms

d. all of the above

e. none of the above

5. The most correct statement regarding thrombolytic therapy in acute myocardial infarction (AMI) is


a. patients younger than 65   years benefit more than elderly victims of MI

b. no benefits have been realized when therapy has been instituted after 6 hours of onset of chest pain

c. thrombolytic therapy has improved the prognosis of patients with prior coronary artery bypass grafting (CABG)

d. patients with non-Q MI have benefited as well as patients who sustain Q-wave MIs with thrombolytic therapy

e. a 50% reduction in mortality has been realized when therapy is administered within 3 hours of onset of chest pain

6. Which of the following statements regarding the use of heparin in patients with AMI is (are) true?


a. heparin therapy is used almost routinely with thrombolytic therapy during the acute phase of MI treatment, provided certain criteria are met

b. heparin is recommended whenever there is echocardiographic evidence of left ventricular thrombi

c. heparin should be administered (unless contraindicated) to all patients with acute anterior wall MI

d. heparin is contraindicated in patients with uncontrolled hypertension

e. all of the above

7. Which of the following is (are) a contraindication(s) to the use of thrombolytic therapy in patients with AMI?


a. active gastrointestinal bleeding

b. recent surgery (2   weeks postoperative)

c. history of cerebrovascular accident

d. suspected aortic dissection

e. all of the above

8. Which of the following statements regarding patients admitted to the coronary care unit after presumed MI is (are) true?


a. patients with suspected MIs should have the left ventricular ejection fraction measured before leaving the hospital

b. patients should have an exercise tolerance test on the fourth or fifth hospital day

c. patients should have an exercise stress test performed 4 to 6   weeks after hospitalization

d. a and c

e. none of the above

9. Which of the following is (are) a significant feature(s) of the pathophysiologic process of MI?


a. endothelial cell wall damage

b. coronary atherosclerosis

c. thromboxane A2 production

d. all of the above

e. a and b

10. Which of the following is (are) true concerning aspirin in the treatment of AMI?


a. aspirin may serve as a substitute for streptokinase or t-PA

b. aspirin may serve as a substitute for heparin

c. aspirin may serve as a substitute for beta blockade

d. all of the above

e. none of the above

11. Which of the following statements regarding thrombolytic therapy is (are) false?


a. thrombolytic therapy limits myocardial necrosis

b. thrombolytic therapy preserves left ventricular function

c. thrombolytic therapy reduces mortality

d. all of the above

e. none of the above

12. Which of the following is true regarding primary angioplasty in the treatment of acute ST-segment elevated MI?


a. primary angioplasty is not a substitute for thrombolytic therapy

b. its universal adoption is likely to be limited by geography

c. it can be performed in hospitals that do not perform CABG surgery

d. stent placement worsens outcomes

e. operator variables are insignificant

13. Which of the following statements concerning dysrhythmias and dysrhythmic drugs in patients who have sustained an MI is (are) true?


a. premature ventricular contractions are common and should be treated with lidocaine

b. sustained runs of ventricular tachycardia frequently progress to ventricular fibrillation (VF)

c. prophylactic lidocaine is recommended to prevent dysrhythmias in all patients who have sustained an MI

d. none of the above

e. all of the above

14. One of the major patient concerns after an MI is the risk of a second or subsequent attack. In which of the following circumstances is the risk of reinfarction or mortality after MI significantly increased?


a. left ventricular ejection fraction < 40%

b. exercise-induced ischemia

c. non–Q-wave infarction (subendocardial infarction)

d. a and b

e. all of the above

15. Which of the following medications has (have) been shown to be of benefit in some patients who have had an MI?


a. beta blockers

b. coumadin

c. aspirin

d. a and c

e. all of the above

16. Which of the following statements concerning rehabilitation of the patient after an MI is (are) true?


a. sexual intercourse should not resume for at least 3   months

b. patients who have sustained an MI should not work for at least 4   months

c. patients who have sustained an MI gradually may increase activity during 6 to 8   weeks

d. no significant psychological distress regarding the MI has been shown to occur in the patient’s spouse or significant other

e. all of the above

17. The best single confirmatory investigation for AMI is


a. the ECG

b. the height of ST-segment elevation in the affected area (in millimeters) plus the depth of ST-segment depression in the reciprocally affected leads (in millimeters)

c. the creatine kinase isoenzyme MB fraction

d. the presence of dysfunctional heart muscle as demonstrated by echocardiography

e. cardiac troponin levels

18. Sudden death as a result of MI is almost always the result of


a. third-degree heart block resulting from infarction of the atrioventricular node

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Oct 1, 2016 | Posted by in GENERAL SURGERY | Comments Off on Acute ST-Segment Elevation Myocardial Infarction

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