Myocardial Infarction

1. Myocardial Infarction

2. Relationships Among CAD, Stable Angina, and MI Fig. 33-8

3. Relationships Among Stable Angina, Unstable Angina, ACS, and MI • Stable angina • Myocardial demand > myocardial supply • Ischemia is reversible • No intimal disruption; no thrombus** • Unstable angina • Myocardial demand > myocardial supply • Ischemia is reversible • Partially occlusive thrombus that stabilize, lyse, or progress to total occlusion**

4. Relationships Among Stable Angina, Unstable Angina, ACS, and MI • Myocardial Infarction • Myocardial demand > myocardial supply • Non-reversible ischemia leading to cell death • Intimal disruption → arterial spasm & thrombosis • Acute coronary syndrome • Includes both unstable angina and MI because both tend to be caused by intimal disruption and thrombosis • Disruption is oxygen supply is prolonged and not immediately reversible

5. Myocardial Infarction:Etiology and Pathophysiology • Primary reason is disruption of atherosclerotic plaque → platelet aggregation and thrombus formation • Myocardial cyanosis occurs within the 1st 10 seconds of occlusion  ECG changes • Total occlusion  anaerobic metabolism and lactic acid accumulation

6. Fig. 33-9

7. Myocardial Infarction:Etiology and Pathophysiology • Occurs as a result of sustained ischemia, causing irreversible cellular death • Myocardial function is altered • Degree of alteration depends on location and size of infarct

8. Myocardial Infarction:Etiology and Pathophysiology • Contractile function of the heart stops in the areas of myocardial necrosis • Most MIs involve the left ventricle (LV) • Described by the area of occurrence • Lateral, inferior, posterior, anterior, right ventricular, etc.

9. Etiology and PathophysiologyHealing Process • Scar tissue is present by day 10 – 14, but is weak • Healed by 6 weeks post MI • Ventricular remodeling • In attempt to compensate for the infarcted muscle, the normal myocardium will hypertrophy and dilate

10. Myocardial Infarction“Typical” Symptoms • Pain • Chest pain not relieved by rest, position change, or nitrates • Pressure, aching, burning, crushing, squeezing, swelling, or heavy in quality • The hallmark of an MI • Dyspnea, diaphoreses, N & V

11. Myocardial Infarction“Atypical” Symptoms • Up to 1/3 of patients do not experience chest pain • Dyspnea, nausea/ vomiting, feeling faint or light-headed, and sweating or “fever” • Those without chest pain delay longer in seeking Rx • Up to 10% of MIs are totally asymptomatic (i.e., “silent MI”)

12. Atypical symptoms more likely to occur among • Women • Elderly • Diabetics • CHF • African Americans

13. Other Clinical Manifestations Myocardial Infarction • Fever • May  within 1st 24 hours up to 100.4° • May last as long as 1 week • Systemic manifestation of the inflammatory process caused by cell death

14. Clinical Manifestations Myocardial Infarction • Cardiovascular manifestations indicating complication of CHF •  BP and heart rate initially • Later the BP may drop from  CO •  urine output • Crackles • Hepatic engorgement • Peripheral edema

15. Complications of Myocardial Infarction • Dysrhythmias • Most common complication • Present in 80% of MI patients • Most common cause of death in the prehospital period

16. Complications of Myocardial Infarction • Congestive heart failure • A complication that occurs when the pumping power of the heart has diminished

17. Complications of Myocardial Infarction • Cardiogenic shock • Occurs when inadequate oxygen and nutrients are supplied to the tissues because of severe LV failure • Requires aggressive management

18. Complications of Myocardial Infarction • Papillary muscle dysfunction • Causes mitral valve regurgitation • Condition aggravates an already compromised LV

19. Complications of Myocardial Infarction • Ventricular aneurysm • Results when the infarcted myocardial wall becomes thinned and bulges out during contraction

20. Complications of Myocardial Infarction • Pericarditis • Inflammation of the pericardium • May result in cardiac compression,  LV filling and emptying, and cardiac failure (cardiac tamponade)

21. Complications of Myocardial Infarction • Dressler syndrome • Characterized by pericarditis with effusion and fever that develops 1 to 4 weeks after MI

22. Diagnostic StudiesMyocardial Infarction • History of pain • Risk factors • Health history • ECG – characteristic changes of MI • Serum cardiac markers (troponin, CK MB)

24. Cardiac Markers • Troponin • Muscle protein released into blood after MI • Rises in 3 – 12 hrs; peak at 24 – 48 hrs, returns to baseline in 5 – 14 days • CK MB • Enzymes released into blood after MI • Rises 3 -12 hrs, peaks 24 hr, returns to baseline in 2 – 3 days

25. Collaborative CareMyocardial Infarction • Fibrinolytic therapy • Percutaneous coronary intervention (PCI), more commonly called PTCA (percutaneous transluminal coronary angioplasty)

26. PTCA with Stent

27. Fibrinolytic Therapy • Lyses thrombi (cardiac and others), thus halting progression of MI • Ideally, treatment should occur within 6 hr of onset of MI • Contra-indications • Conditions that put patient at high risk of hemorrhage (Table 33-14) • Prevent and monitor for bleeding

28. Collaborative CareMyocardial Infarction • Drug Therapy • IV nitroglycerin • Antiarrhythmic drugs • Morphine

29. Collaborative CareMyocardial Infarction • Drug Therapy • -Adrenergic blockers • ACE inhibitors • Stool softeners

30. Collaborative CareMyocardial Infarction • Nutritional Therapy • Diet restricted in saturated fats and cholesterol • Low sodium

31. Nursing ManagementAngina and Myocardial InfarctionNursing Diagnoses • Acute pain • Ineffective tissue perfusion • Anxiety • Activity intolerance • Ineffective therapeutic regimen management

32. Nursing ManagementAngina and Myocardial InfarctionPlanning • Overall goals: • Relief of pain • No progression of MI • Immediate and appropriate treatment

33. Nursing ManagementAngina and Myocardial InfarctionPlanning • Overall goals: • Cope effectively with associated anxiety • Cooperation of rehabilitation plan • Modify or alter risk factors

34. Nursing ManagementAngina and Myocardial InfarctionNursing Implementation: Angina • Acute Intervention • Administration of oxygen • Vital signs • ECG • Pain relief

35. Nursing ManagementAngina and Myocardial InfarctionNursing Implementation: MI • Acute Intervention • Morphine • Continuous ECG • Frequent vital signs • Rest and comfort

36. Nursing ManagementAngina and Myocardial InfarctionNursing Implementation: MI • Acute Intervention • Anxiety • Emotional and behavioral reactions • Communicate with family • Provide support

37. Nursing ManagementAngina and Myocardial InfarctionNursing Implementation: MI • Ambulatory and Home Care • Rehabilitation • Cardiac rehabilitation • Physical exercise

38. Nursing ManagementAngina and Myocardial InfarctionNursing Implementation: MI • Ambulatory and Home Care • Resumption of sexual activity • Emotional readiness • Physical training

39. Sudden Cardiac Death • Unexpected death from cardiac causes • Disruption in cardiac function • Abrupt loss of cerebral blood flow

40. Sudden Cardiac Death • Usually occurs within 1 hour of onset of symptoms • Occurs secondary to natural causes • Accounts for about 50% of all deaths from cardiovascular causes • Mostly caused by ventricular arrhythmias

41. Sudden Cardiac DeathNursing and Collaborative Management • Implantable cardioverter-defibrillator (ICD)