Myocardial Infarction

Myocardial InfarctionMyocardial 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 1st 10 seconds of occlusion ECG changes

• Total occlusion anaerobic metabolism and lactic acid accumulation

• 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

Fig. 33-9


• 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

• 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


• 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.

• 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 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

• 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

• 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 1st 24 hours up to 100.4°

– May last as long as 1 week

– Systemic manifestation of the inflammatory process caused by cell death

• 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

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

• 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

• Dysrhythmias

– Most common complication

– Present in 80% of MI patients

– Most common cause of death in the prehospital period


• Congestive heart failure

– A complication that occurs when the pumping power of the heart has diminished

• Congestive heart failure

– A complication that occurs when the pumping power of the heart has diminished


• Cardiogenic shock

– Occurs when inadequate oxygen and nutrients are supplied to the tissues because of severe LV failure

– Requires aggressive management

• Cardiogenic shock

– Occurs when inadequate oxygen and nutrients are supplied to the tissues because of severe LV failure

– Requires aggressive management


• Papillary muscle dysfunction

– Causes mitral valve regurgitation

– Condition aggravates an already compromised LV

• Papillary muscle dysfunction

– Causes mitral valve regurgitation

– Condition aggravates an already compromised LV


• Ventricular aneurysm

– Results when the infarcted myocardial wall becomes thinned and bulges out during contraction

• Ventricular aneurysm

– Results when the infarcted myocardial wall becomes thinned and bulges out during contraction


• Pericarditis

– Inflammation of the pericardium

– May result in cardiac compression, LV filling and emptying, and cardiac failure (cardiac tamponade)

• Pericarditis

– Inflammation of the pericardium

– May result in cardiac compression, LV filling and emptying, and cardiac failure (cardiac tamponade)


• Dressler syndrome

– Characterized by pericarditis with effusion and fever that develops 1 to 4 weeks after MI

• Dressler syndrome

– Characterized by pericarditis with effusion and fever that develops 1 to 4 weeks after MI

Diagnostic StudiesMyocardial Infarction

• History of pain

• Risk factors

• Health history

• ECG – characteristic changes of MI

• Serum cardiac markers (troponin, CK MB)

• 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 CareMyocardial Infarction

• Fibrinolytic therapy

• Percutaneous coronary intervention (PCI), more commonly called PTCA (percutaneous transluminal coronary angioplasty)

• 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


• Drug Therapy

– IV nitroglycerin

– Antiarrhythmic drugs

– Morphine

• Drug Therapy

– IV nitroglycerin

– Antiarrhythmic drugs

– Morphine


• Drug Therapy -Adrenergic blockers

– ACE inhibitors

– Stool softeners

• Drug Therapy -Adrenergic blockers

– ACE inhibitors

– Stool softeners


• Nutritional Therapy

– Diet restricted in saturated fats and cholesterol

– Low sodium

• Nutritional Therapy

– Diet restricted in saturated fats and cholesterol

– Low sodium

Nursing ManagementAngina and Myocardial Infarction

Nursing Diagnoses

• Acute pain

• Ineffective tissue perfusion

• Anxiety

• Activity intolerance

• Ineffective therapeutic regimen management

• Acute pain

• Ineffective tissue perfusion

• Anxiety

• Activity intolerance

• Ineffective therapeutic regimen management


Planning

• Overall goals:

– Relief of pain

– No progression of MI

– Immediate and appropriate treatment

• Overall goals:

– Relief of pain

– No progression of MI

– Immediate and appropriate treatment


Planning

• Overall goals:

– Cope effectively with associated anxiety

– Cooperation of rehabilitation plan

– Modify or alter risk factors

• Overall goals:

– Cope effectively with associated anxiety

– Cooperation of rehabilitation plan

– Modify or alter risk factors


Nursing Implementation: Angina

• Acute Intervention

– Administration of oxygen

– Vital signs

– ECG

– Pain relief


– Administration of oxygen

– Vital signs

– ECG

– Pain relief


Nursing Implementation: MI


– Morphine

– Continuous ECG

– Frequent vital signs

– Rest and comfort


– Morphine

– Continuous ECG

– Frequent vital signs

– Rest and comfort




– Anxiety

– Emotional and behavioral reactions

• Communicate with family

• Provide support


– Anxiety

– Emotional and behavioral reactions

• Communicate with family

• Provide support



• Ambulatory and Home Care

– Rehabilitation

– Cardiac rehabilitation

– Physical exercise


– Rehabilitation

– Cardiac rehabilitation

– Physical exercise




– Resumption of sexual activity

• Emotional readiness

• Physical training


– 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

• 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

• 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)

• Implantable cardioverter-defibrillator (ICD)

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Myocardial Infarction