Myocardial Infarction Relationships Among CAD Stable Angina and
Myocardial Infarction
Relationships Among CAD, Stable Angina, and MI Fig. 33 -8
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**
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
Myocardial Infarction: Etiology and Pathophysiology • Primary reason is disruption of atherosclerotic plaque → platelet aggregation and thrombus formation • Myocardial cyanosis occurs within the 1 st 10 seconds of occlusion ECG changes • Total occlusion anaerobic metabolism and lactic acid accumulation
Fig. 33 -9
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
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.
Etiology and Pathophysiology Healing 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
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
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”)
• Atypical symptoms more likely to occur among – Women – Elderly – Diabetics – CHF – African Americans
Other Clinical Manifestations Myocardial Infarction • Fever – May within 1 st 24 hours up to 100. 4° – May last as long as 1 week – Systemic manifestation of the inflammatory process caused by cell death
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
Complications of Myocardial Infarction • Dysrhythmias – Most common complication – Present in 80% of MI patients – Most common cause of death in the prehospital period
Complications of Myocardial Infarction • Congestive heart failure – A complication that occurs when the pumping power of the heart has diminished
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
Complications of Myocardial Infarction • Papillary muscle dysfunction – Causes mitral valve regurgitation – Condition aggravates an already compromised LV
Complications of Myocardial Infarction • Ventricular aneurysm – Results when the infarcted myocardial wall becomes thinned and bulges out during contraction
Complications of Myocardial Infarction • Pericarditis – Inflammation of the pericardium – May result in cardiac compression, LV filling and emptying, and cardiac failure (cardiac tamponade)
Complications of Myocardial Infarction • Dressler syndrome – Characterized by pericarditis with effusion and fever that develops 1 to 4 weeks after MI
Diagnostic Studies Myocardial Infarction • • • History of pain Risk factors Health history ECG – characteristic changes of MI Serum cardiac markers (troponin, CK MB)
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
Collaborative Care Myocardial Infarction • Fibrinolytic therapy • Percutaneous coronary intervention (PCI), more commonly called PTCA (percutaneous transluminal coronary angioplasty)
PTCA with Stent
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
Collaborative Care Myocardial Infarction • Drug Therapy – IV nitroglycerin – Antiarrhythmic drugs – Morphine
Collaborative Care Myocardial Infarction • Drug Therapy – -Adrenergic blockers – ACE inhibitors – Stool softeners
Collaborative Care Myocardial Infarction • Nutritional Therapy – Diet restricted in saturated fats and cholesterol – Low sodium
Nursing Management Angina and Myocardial Infarction Nursing Diagnoses • • • Acute pain Ineffective tissue perfusion Anxiety Activity intolerance Ineffective therapeutic regimen management
Nursing Management Angina and Myocardial Infarction Planning • Overall goals: – Relief of pain – No progression of MI – Immediate and appropriate treatment
Nursing Management Angina and Myocardial Infarction Planning • Overall goals: – Cope effectively with associated anxiety – Cooperation of rehabilitation plan – Modify or alter risk factors
Nursing Management Angina and Myocardial Infarction Nursing Implementation: Angina • Acute Intervention – Administration of oxygen – Vital signs – ECG – Pain relief
Nursing Management Angina and Myocardial Infarction Nursing Implementation: MI • Acute Intervention – Morphine – Continuous ECG – Frequent vital signs – Rest and comfort
Nursing Management Angina and Myocardial Infarction Nursing Implementation: MI • Acute Intervention – Anxiety – Emotional and behavioral reactions • Communicate with family • Provide support
Nursing Management Angina and Myocardial Infarction Nursing Implementation: MI • Ambulatory and Home Care – Rehabilitation – Cardiac rehabilitation – Physical exercise
Nursing Management Angina and Myocardial Infarction Nursing Implementation: MI • Ambulatory and Home Care – Resumption of sexual activity • Emotional readiness • Physical training
Sudden Cardiac Death • Unexpected death from cardiac causes • Disruption in cardiac function • Abrupt loss of cerebral blood flow
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
Sudden Cardiac Death Nursing and Collaborative Management • Implantable cardioverter-defibrillator (ICD)
- Slides: 41