Myocardial Infarction Overview and Practice Questions Vector

Myocardial Infarction: Overview and Practice Questions

by | Updated: Apr 6, 2024

Myocardial infarction, commonly known as a heart attack, is a life-threatening medical condition that occurs when the blood supply to a portion of the heart muscle is suddenly blocked, usually due to a blood clot.

This blockage deprives the heart muscle of oxygen and nutrients, leading to tissue damage or death if not promptly treated.

Myocardial infarction is a significant health concern worldwide, with millions of individuals affected each year.

Understanding its causes, risk factors, symptoms, and treatment options is crucial for both prevention and timely intervention.

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What is a Myocardial Infarction?

A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow to a part of the heart is blocked, often by a blood clot, leading to damage or death of heart muscle due to lack of oxygen. Prompt medical attention is critical for survival.

Myocardial Infarction Heart Attack Vector

Risk Factors

A myocardial infarction (MI) is often a result of coronary artery disease. Key risk factors include:

  • Hypertension
  • Hyperlipidemia
  • Smoking
  • Diabetes
  • Obesity
  • Sedentary lifestyle
  • Family history of heart disease
  • Age (risk increases for men over 45 and women over 55)
  • Stress

Signs and Symptoms

The hallmark symptom of myocardial infarction is chest pain or discomfort, typically described as pressure, squeezing, or a feeling of fullness in the center of the chest.

Other symptoms may include:

  • Pain or discomfort in the arms, left shoulder, elbows, jaw, or back
  • Shortness of breath
  • Nausea or vomiting
  • Lightheadedness or fainting
  • Sweating
  • Fatigue

Diagnosis

Diagnosis of myocardial infarction is primarily based on:

  • Patient history and clinical symptoms
  • Electrocardiogram (ECG) to detect electrical changes in the heart
  • Blood tests for cardiac biomarkers (such as troponin) that are released when the heart muscle is damaged

Treatment

Immediate treatment for a heart attack is crucial for survival and may include:

  • Cardiovascular medications such as aspirin, thrombolytics (to dissolve clots), beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors
  • Percutaneous coronary intervention (PCI), commonly known as coronary angioplasty, to open blocked arteries
  • Coronary artery bypass grafting (CABG) in severe cases
  • Long-term treatment involves lifestyle modification, medication for risk factor management, cardiac rehabilitation, and possibly the use of implantable devices like stents or pacemakers.

Note: Prompt recognition and treatment of MI can significantly improve outcomes and reduce the risk of heart failure or death. Regular check-ups and managing risk factors are essential for those with known heart disease or multiple risk factors.

Myocardial Infarction Practice Questions

1. What is the definition of a myocardial infarction?
A myocardial infarction (i.e., heart attack) is a medical emergency where a blockage in the coronary arteries cuts off blood supply to the heart, causing tissue damage or death.

2. What is the chief complaint for a heart attack?
Chest pain or pressure

3. What are some other symptoms of a myocardial infarction?
Nausea, vomiting, shortness of breath, and diaphoresis.

4. What are the risk factors of a myocardial infarction?
Coronary artery disease, hypertension, high-density lipoproteins, diabetes mellitus, smoking, family history of coronary artery disease, greater than 55 years old, sedentary lifestyle, and obesity. This condition is twice as likely to occur in men as in women. It has the highest prevalence in African American men ages 45 and older and for women 55 and older.

5. How are heart attacks diagnosed?
EKG (STEMI) or elevated troponin (non-STEMI).

6. What medications are used to treat a heart attack?
ASA, NTG, and thrombolytic (Heparin).

7. What is the incidence of a myocardial infarction?
The incidence decreases with higher socioeconomic status, and less than 10 percent are fatal in the United States.

8. What are the causes of a myocardial infarction?
Coronary atherosclerosis, atherosclerotic plaque where there is a large amount of fat or cholesterol in the diet, coronary vasospasm, thrombosis, increased vasomotor tone, chest trauma (laceration or contusion), severe anemia, and collagen vascular disease.

9. What diagnostic tools are used for a myocardial infarction?
ECG is used to record the electrical activity of the heart via electrodes on the skin. Blood tests are done to assess the enzymes present in the blood. Other tests include chest x-rays, arterial blood gas (ABG), echocardiograms, angiograms, and exercise stress tests.

10. What are the complications of a myocardial infarction?
Heart arrhythmias, heart failure, heart rupture, valve damage, stroke, angina, and pericarditis.

11. What happens during the early stages of a myocardial infarction?
The patient experiences chest pain.

12. What happens during the later stages of a myocardial infarction?
One or more arteries become completely blocked, causing a heart attack and damage/death of heart tissue due to lack of blood flow and oxygen to the tissue.

13. What is the prognosis of a myocardial infarction?
Survival rates have increased steadily since 1970.

14. What can be seen on the ECG of patients with a myocardial infarction?
An elevated ST segment.

15. What is the purpose of a stress test?
It determines the effectiveness of oxygen delivery to myocardial tissue.

16. What specific enzymes are released by dying muscle?
Cardiac troponin and creatinine phosphokinase.

17. What population commonly has silent myocardial infarctions?
Elderly, post-menopausal women, and diabetics.

18. What is the Levine’s sign?
Clenched right fist held over the chest to describe ischemic chest pain.

19. What is common for an EKG diagnosis of a myocardial infarction?
ST-elevation or depression, T-wave inversion, and Q-waves.

20. Why does the heart need the coronary arteries?
The myocardium is too thick for diffusion to take place efficiently.

21. What is atherosclerosis?
Atherosclerosis is a chronic condition characterized by the buildup of plaque inside arteries, leading to reduced blood flow and increased risk of cardiovascular events.

22. How long does it take for plaque to form and cause a clinically significant event?
Decades

23. What is stable angina?
Stable angina is a condition marked by predictable chest pain or discomfort typically triggered by physical exertion or stress due to reduced blood flow to the heart.

24. What is angina pectoris?
Angina pectoris is a clinical syndrome characterized by chest discomfort or pain due to transient myocardial ischemia, which occurs when the demand for oxygen by the heart muscle exceeds the supply.

25. What is unstable angina?
Unstable angina is a form of acute coronary syndrome where unexpected chest pain occurs at rest or with minimal exertion, signaling a high risk of imminent myocardial infarction.

26. What is a thrombosis?
When a clot completely blocks a vessel.

27. What happens during a heart attack?
During a heart attack, a blockage in the coronary arteries interrupts blood flow to the heart, causing heart muscle cells to be deprived of oxygen and leading to tissue damage or death.

28. What does an angioplasty use to do its job?
A balloon

29. What is an angiogram?
A method for looking at the coronary vessels under a live x-ray that uses radioactive dye and imaging to locate blockages.

30. What is a stent?
A mesh material that holds a plaque against the arterial wall, allowing blood flow through the vessel.

31. What is PCI?
Percutaneous Coronary Intervention.

32. What is a mural thrombus?
Blood that no longer pumps through the heart and clots, eventually turning into fibrous tissue.

33. When does instant death occur from a heart attack?
It occurs when a heart attack softens the affected myocardium, thus leading to a rupture of the heart wall itself.

34. What is a coronary artery bypass graft (CABG)?
A surgical procedure that improves blood flow to the heart by diverting blood around narrowed or blocked coronary arteries using grafts.

35. What is an infarction?
Necrosis (i.e., tissue death) from a lack of blood supply.

36. What do coronary thrombosis and vascular spasms cause?
They can cause a complete block of part of the coronary circulation and death of cardiac muscle cells beyond the blockage.

37. What does the severity of the heart attack depend on?
The site and nature of the blockage.

38. What causes endothelial damage?
Endothelial damage is often caused by risk factors such as high blood pressure, smoking, high cholesterol, diabetes, and inflammation, which can compromise the integrity of the inner arterial lining, leading to atherosclerosis and cardiovascular diseases.

39. How does aspirin help treat a heart attack?
Aspirin helps treat a heart attack by inhibiting platelets, which prevents the formation of new blood clots and reduces the growth of existing ones, thereby improving blood flow to the heart muscle.

40. What is an EKG?
An electrocardiogram (EKG or ECG) is a diagnostic tool that records the electrical activity of the heart to help detect and monitor cardiac conditions.

41. What is an echocardiogram?
An echocardiogram is a noninvasive ultrasound test that uses sound waves to create images of the heart, allowing doctors to assess its structure and function.

42. What is the most common cause of a heart attack?
A blood clot that blocks one of the coronary arteries.

43. What causes a blood clot?
Blood clots are caused by factors such as endothelial injury, slow or turbulent blood flow, and hypercoagulability, which can lead to the aggregation of platelets and the activation of coagulation factors, resulting in the formation of a thrombus.

44. What is plaque made up of?
Plaque is composed of lipids, particularly cholesterol, calcium deposits, fibrin, cellular waste, and a variety of cells, including smooth muscle cells and inflammatory cells such as macrophages.

45. What happens when the plaque inside a blood vessel tears?
Platelets form blood clots at the sight of the tear, which blocks the vessel.

46. What are the normal levels of creatine phosphokinase?
10-120 mcg/liter of blood

47. What level of creatine phosphokinase indicates a heart attack?
400-800 mcg/liter

48. What causes heart tissue to die at a faster-than-normal rate?
Blood clots in the coronary arteries.

49. What is the job of the coronary arteries?
To provide the heart muscle with oxygenated blood.

55. What are the phases of a heart attack? 
Hyperacute phase, fully enveloped phase, resolution phase, and permanent phase.

51. What is the fully enveloped phase?
Appears a few hours to days after a heart attack.

52. What is the resolution phase?
Appears weeks after a heart attack.

53. What is the stabilized chronic phase?
The final phase that shows permanent changes compared to a normal EKG.

54. What is the hyperacute phase?
Happens directly after a heart attack. 

55. As a respiratory therapist, when a patient presents with signs of a heart attack, what’s the first thing you should do?
Give the patient 100% oxygen.

56. How fast do creatine phosphokinase levels rise?
Within 8-24 hours

57. What is the normal level of white blood cells?
4,000-10,000

58. What level of white blood cells may indicate a heart attack?
12,000-15,000

59. How often do they perform a creatine phosphokinase blood test?
Every hour for 24 hours.

60. Why is it important to check the creatine phosphokinase levels often?
If they keep rising, patients may still be experiencing a myocardial infarction.

61. What is the immediate treatment for a heart attack?
Intravascular line (IV), blood thinners (e.g., aspirin), heart monitor, and 100% oxygen.

62. When is an electric shock (defibrillator) indicated?
When the patient has an arrhythmia with a shockable rhythm.

63. What chemical is used to relax the blood vessels?
Nitroglycerin

64. What is coronary artery disease?
The atherosclerotic narrowing of the coronary arteries.

65. What does plaque lead to in coronary artery disease?
Ischemia

66. What are the risk factors for coronary artery disease?
Smoking, hyperlipidemia, diabetes mellitus, obesity, sedentary lifestyle, and uncontrollable stress.

67. What are the entrance criteria for metabolic syndrome?
Hypertension, abdominal obesity, and pre-diabetes.

68. What are the risk factors for an acute myocardial infarction?
Smoking, hypertension, genetics, and obesity.

69. What decreases the risk of an acute myocardial infarction?
No smoking, healthy diet, exercise, and moderate alcohol consumption.

70. How does plaque form?
Plaque forms when the inner wall of an artery is damaged by factors like high cholesterol or hypertension. This leads to a build-up of LDL cholesterol, white blood cells, and other substances, creating a hard, fatty deposit that narrows the artery and impedes blood flow.

Final Thoughts

Myocardial infarction remains a critical medical emergency that demands immediate attention.

Its impact on individuals and healthcare systems is substantial, and its prevention through lifestyle modifications and risk factor management is paramount.

Recognizing the symptoms and seeking prompt medical care can make a crucial difference in the outcome of a heart attack.

With ongoing research and advancements in medical science, the management and treatment of myocardial infarction continue to evolve, offering hope for improved outcomes and better quality of life for those affected by this condition.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.

References

  • Rrt, Des Terry Jardins MEd, and Burton George Md Facp Fccp Faarc. Clinical Manifestations and Assessment of Respiratory Disease. 8th ed., Mosby, 2019.
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Ojha N, Dhamoon AS. Myocardial Infarction. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.

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