Heart Attack (Myocardial Infarction): A Comprehensive Guide : Including Nursing Care ||

 

Heart Attack (Myocardial Infarction): A Comprehensive Guide

1. DEFINITION

Myocardial Infarction (MI), commonly known as a heart attack, is the irreversible necrosis (death) of heart muscle tissue resulting from prolonged ischemia due to an imbalance between myocardial oxygen supply and demand. This occurs when blood flow to a portion of the heart muscle is severely reduced or completely blocked, typically for more than 20-30 minutes.

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Types of Myocardial Infarction:

Type	Description
STEMI	ST-Elevation Myocardial Infarction - complete coronary artery occlusion
NSTEMI	Non-ST-Elevation Myocardial Infarction - partial occlusion
Type 1	Spontaneous MI due to atherosclerotic plaque rupture
Type 2	MI secondary to ischemic imbalance (supply-demand mismatch)
Type 3	MI resulting in sudden cardiac death
Type 4	MI related to PCI (Percutaneous Coronary Intervention)
Type 5	MI related to CABG (Coronary Artery Bypass Grafting)

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2. CAUSES

Primary Causes:

A. Atherosclerosis (Most Common - 90% of cases)

• Progressive buildup of fatty plaques in coronary arteries
• Plaque rupture leading to thrombus formation
• Complete or partial arterial occlusion

B. Coronary Artery Thrombosis

• Blood clot formation at the site of plaque rupture
• Platelet aggregation and fibrin deposition
• Acute vessel occlusion

C. Coronary Artery Spasm (Prinzmetal's Angina)

• Sudden constriction of coronary arteries
• Temporary reduction in blood flow
• Can occur in normal or diseased arteries

D. Coronary Artery Embolism

• Emboli from cardiac sources (atrial fibrillation, valve disease)
• Paradoxical emboli through patent foramen ovale

E. Other Causes:

• Coronary artery dissection - spontaneous or traumatic
• Vasculitis - Kawasaki disease, polyarteritis nodosa
• Hypercoagulable states - Factor V Leiden, protein C/S deficiency
• Cocaine/amphetamine abuse - causing vasospasm and thrombosis
• Severe anemia or hypoxia - demand-supply mismatch
• Aortic stenosis - reduced coronary perfusion

3. PREDISPOSING FACTORS (RISK FACTORS)

A. Non-Modifiable Risk Factors:

Factor	Details
Age	Men >45 years; Women >55 years
Gender	Males at higher risk; females catch up post-menopause
Family History	First-degree relative with premature CAD (male <55, female <65)
Race/Ethnicity	Higher risk in South Asians, African Americans
Genetic Factors	Familial hypercholesterolemia, Lp(a) elevation

B. Modifiable Risk Factors:

Behavioral Factors:

1. Smoking/Tobacco use
• Endothelial damage
• Increased platelet aggregation
• Reduced HDL cholesterol
• Carbon monoxide reducing oxygen-carrying capacity
2. Physical Inactivity
• Sedentary lifestyle
• Poor cardiovascular conditioning
3. Unhealthy Diet
• High saturated fat intake
• High sodium consumption
• Low fiber diet
• Excessive processed foods
4. Alcohol Abuse
• Cardiomyopathy
• Hypertension
• Arrhythmias

Medical Conditions:

1. Hypertension
• Increased afterload
• Left ventricular hypertrophy
• Accelerated atherosclerosis
2. Diabetes Mellitus
• Accelerated atherosclerosis
• Endothelial dysfunction
• Silent ischemia common
3. Dyslipidemia
• Elevated LDL cholesterol
• Low HDL cholesterol
• Elevated triglycerides
4. Obesity
• BMI >30 kg/m²
• Central/abdominal obesity
• Metabolic syndrome
5. Metabolic Syndrome
• Cluster of risk factors
• Insulin resistance
• Pro-inflammatory state

Psychosocial Factors:

• Chronic stress
• Depression and anxiety
• Type A personality
• Social isolation
• Low socioeconomic status

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4. CLINICAL MANIFESTATIONS

Classic Symptoms:

Chest Pain (Angina):

• Character: Crushing, squeezing, pressure, tightness, heaviness
• Location: Substernal/retrosternal, left-sided chest
• Radiation: Left arm, jaw, neck, back, epigastrium
• Duration: >20 minutes, not relieved by rest or nitroglycerin
• Associated symptoms: Dyspnea, diaphoresis, nausea

Associated Symptoms:

• Profuse sweating (diaphoresis)
• Shortness of breath (dyspnea)
• Nausea and vomiting
• Palpitations
• Anxiety/sense of impending doom
• Lightheadedness/dizziness
• Fatigue and weakness

Atypical Presentations:

• Women: Fatigue, indigestion, neck/back pain
• Elderly: Confusion, syncope, weakness
• Diabetics: Silent MI (no chest pain)
• Epigastric pain: Mistaken for GI problems

Physical Examination Findings:

• Tachycardia or bradycardia
• Hypotension or hypertension
• Diaphoresis, pallor, cool clammy skin
• S3 or S4 heart sounds
• New murmurs (mitral regurgitation)
• Jugular venous distension
• Pulmonary crackles (if heart failure)

 5. Investigations (Diagnostic Tests)

A. Electrocardiogram (ECG) – Gold Standard for Immediate Diagnosis

• T-wave inversion: Indicates ischemia.
• ST-segment elevation: Indicates injury (Acute STEMI).
• Pathologic Q-wave: Indicates necrosis (permanent damage/old MI).

B. Cardiac Markers (Blood Tests)

• Troponin I & T: The most specific and sensitive markers for heart damage. They rise within 3-4 hours and stay elevated for up to 2 weeks.
• CK-MB (Creatine Kinase-MB): Specific to heart muscle; rises in 4-6 hours, peaks at 24 hours.
• Myoglobin: Rises very early (2 hours) but is not specific to the heart.

C. Imaging

• Echocardiogram: Visualizes wall motion abnormalities and measures Ejection Fraction (EF).
• Coronary Angiography (Cardiac Cath): Dye is injected to visualize the exact location and severity of the blockage.

D. Laboratory Investigations

Test	Purpose
Complete Blood Count	Anemia, infection, leukocytosis
Lipid Profile	Risk stratification
Blood Glucose/HbA1c	Diabetes screening
Renal Function Tests	Kidney function, contrast safety
Electrolytes	K+, Mg2+ levels (arrhythmia risk)
Coagulation Profile	Bleeding risk assessment
BNP/NT-proBNP	Heart failure evaluation
Thyroid Function	Secondary causes
Liver Function Tests	Hepatic congestion

6. TREATMENT

A. Immediate Management (First Hour - "Golden Hour")

MONA Protocol:

• Morphine - 2-4 mg IV for pain (use with caution)
• Oxygen - If SpO2 <90% or respiratory distress
• Nitrates - Sublingual NTG 0.4 mg every 5 minutes × 3 doses
• Aspirin - 162-325 mg chewed immediately

Additional Immediate Measures:

1. IV Access - Two large-bore cannulas
2. Continuous Monitoring - ECG, SpO2, BP
3. 12-lead ECG - Within 10 minutes
4. Pain Management - Morphine if needed
5. Antiemetics - For nausea
6. Beta-blockers - If no contraindications

B. Reperfusion Therapy (Critical for STEMI)

1. Primary Percutaneous Coronary Intervention (PCI):

• Preferred method when available within 120 minutes
• Door-to-balloon time goal: <90 minutes
• Involves balloon angioplasty ± stenting
• Drug-eluting stents (DES) preferred

2. Fibrinolytic Therapy:

• When PCI not available within 120 minutes
• Door-to-needle time goal: <30 minutes
• Agents:
• Alteplase (tPA)
• Reteplase (rPA)
• Tenecteplase (TNK-tPA)
• Streptokinase

Contraindications to Fibrinolysis:

Absolute	Relative
Previous intracranial hemorrhage	History of chronic hypertension
Known cerebral vascular lesion	Severe uncontrolled hypertension (>180/110)
Ischemic stroke within 3 months	History of ischemic stroke >3 months
Active bleeding	Traumatic CPR
Suspected aortic dissection	Recent major surgery (<3 weeks)
Significant closed head trauma	Non-compressible vascular punctures

3. Coronary Artery Bypass Grafting (CABG):

• Left main disease
• Multi-vessel disease
• Failed PCI
• Mechanical complications

C. Pharmacological Therapy

1. Antiplatelet Therapy:

Drug	Dose	Duration
Aspirin	75-100 mg daily	Lifelong
P2Y12 Inhibitors:
- Clopidogrel	75 mg daily	12 months
- Prasugrel	10 mg daily	12 months
- Ticagrelor	90 mg twice daily	12 months

2. Anticoagulation:

• Unfractionated Heparin (UFH) - IV bolus + infusion
• Enoxaparin (LMWH) - 1 mg/kg SC q12h
• Fondaparinux - 2.5 mg SC daily
• Bivalirudin - During PCI

3. Beta-Blockers:

• Metoprolol 25-50 mg orally
• Carvedilol 3.125-6.25 mg twice daily
• Bisoprolol 2.5-5 mg daily
• Reduce myocardial oxygen demand
• Continue indefinitely post-MI

4. ACE Inhibitors/ARBs:

• Ramipril 2.5-10 mg daily
• Lisinopril 5-40 mg daily
• Valsartan (if ACE-I intolerant)
• Start within 24 hours if stable
• Continue indefinitely

5. Statins (High-Intensity):

• Atorvastatin 40-80 mg daily
• Rosuvastatin 20-40 mg daily
• Target LDL <70 mg/dL
• Start immediately, continue lifelong

6. Other Medications:

• Aldosterone antagonists (Spironolactone/Eplerenone) - If LVEF ≤40%
• Nitrates - For ongoing angina
• Proton pump inhibitors - GI protection with DAPT
• Analgesics - Pain control

D. Management of Complications

Complication	Management
Cardiogenic shock	Inotropes, IABP, mechanical support
Arrhythmias	Antiarrhythmics, defibrillation, pacing
Heart failure	Diuretics, ACE-I, beta-blockers
Mechanical complications	Surgical repair
Pericarditis	NSAIDs, colchicine
Left ventricular thrombus	Anticoagulation

7. NURSING MANAGEMENT

A. Nursing Assessment

1. Primary Assessment (ABCDE Approach):

• Airway: Patency, secretions
• Breathing: Rate, depth, SpO2, breath sounds
• Circulation: Heart rate, BP, peripheral perfusion, ECG
• Disability: Level of consciousness, pain level
• Exposure: Full examination, temperature

2. Comprehensive Assessment:

Cardiovascular Assessment:

• Continuous ECG monitoring
• Blood pressure monitoring (invasive if unstable)
• Heart sounds (S3, S4, murmurs)
• Jugular venous pressure
• Peripheral pulses and perfusion
• Capillary refill time
• Edema assessment

Respiratory Assessment:

• Respiratory rate and pattern
• Oxygen saturation
• Breath sounds (crackles, wheezes)
• Use of accessory muscles
• Signs of pulmonary edema

Pain Assessment:

• Location, character, intensity (0-10 scale)
• Radiation pattern
• Aggravating and relieving factors
• Associated symptoms
• Response to treatment

Psychosocial Assessment:

• Anxiety level
• Coping mechanisms
• Family support
• Understanding of condition

B. Nursing Diagnoses

1. Acute Pain related to myocardial ischemia as evidenced by verbal reports, facial grimacing, and diaphoresis
2. Decreased Cardiac Output related to altered myocardial contractility as evidenced by hypotension, tachycardia, and decreased peripheral perfusion
3. Impaired Gas Exchange related to pulmonary congestion as evidenced by dyspnea, decreased SpO2, and abnormal ABGs
4. Anxiety related to fear of death and unfamiliar environment as evidenced by restlessness, expressed concerns, and tachycardia
5. Activity Intolerance related to imbalance between oxygen supply and demand as evidenced by fatigue, dyspnea on exertion, and abnormal vital signs
6. Risk for Decreased Cardiac Tissue Perfusion related to coronary artery occlusion
7. Deficient Knowledge related to new diagnosis and treatment regimen
8. Ineffective Coping related to situational crisis and lifestyle changes

8. NURSING CARE PLAN

Nursing Diagnosis 1: Acute Pain

Component	Details
Assessment	Pain characteristics, vital signs, ECG changes
Goal	Patient will report pain reduction to ≤2/10 within 30 minutes of intervention

Interventions:

Intervention	Rationale
Assess pain using standardized scale (0-10)	Provides baseline and monitors effectiveness
Administer prescribed analgesics (morphine 2-4 mg IV)	Reduces pain, decreases preload, reduces oxygen demand
Administer sublingual nitroglycerin as prescribed	Vasodilation improves coronary blood flow
Maintain bed rest during acute phase	Reduces myocardial oxygen demand
Position patient comfortably (semi-Fowler's)	Reduces cardiac workload
Provide calm, quiet environment	Reduces anxiety and stress
Monitor vital signs before and after medication	Detects hypotension from medications
Apply oxygen therapy as prescribed	Improves myocardial oxygen supply
Reassess pain after interventions	Evaluates effectiveness of treatment
Notify physician if pain unrelieved	May indicate ongoing ischemia or complications

Evaluation: Patient reports pain ≤2/10, appears comfortable, vital signs stable

Nursing Diagnosis 2: Decreased Cardiac Output

Component	Details
Assessment	BP, HR, cardiac rhythm, urine output, peripheral perfusion
Goal	Patient will maintain adequate cardiac output as evidenced by stable vital signs, adequate urine output (>0.5 mL/kg/hr), and warm extremities

Interventions:

Intervention	Rationale
Continuous cardiac monitoring	Detects arrhythmias early
Monitor vital signs hourly	Identifies hemodynamic instability
Assess heart sounds every 4 hours	Detects new murmurs or S3/S4
Monitor urine output hourly	Reflects renal perfusion
Assess peripheral pulses and perfusion	Indicates cardiac output adequacy
Administer inotropic agents as prescribed	Improves contractility if needed
Maintain IV access	Ensures medication administration route
Monitor intake and output	Evaluates fluid balance
Elevate head of bed 30-45 degrees	Reduces preload and dyspnea
Restrict fluids if ordered	Prevents fluid overload
Prepare for emergency interventions	Ready for defibrillation, pacing if needed

Evaluation: Vital signs within normal limits, urine output adequate, peripheral perfusion intact

Nursing Diagnosis 3: Impaired Gas Exchange

Component	Details
Assessment	Respiratory status, SpO2, ABGs, breath sounds
Goal	Patient will maintain SpO2 >94% and demonstrate clear breath sounds

Interventions:

Intervention	Rationale
Monitor respiratory rate and pattern	Detects respiratory distress early
Continuous pulse oximetry	Monitors oxygenation status
Administer oxygen therapy to maintain SpO2 >94%	Improves oxygen delivery
Auscultate breath sounds every 2-4 hours	Detects pulmonary congestion
Position in high Fowler's if dyspneic	Facilitates lung expansion
Monitor ABGs as ordered	Provides objective data on gas exchange
Administer diuretics as prescribed	Reduces pulmonary congestion
Limit fluid intake as ordered	Prevents fluid overload
Encourage deep breathing exercises	Promotes lung expansion
Suction if necessary	Clears secretions

Evaluation: SpO2 maintained >94%, clear breath sounds, no dyspnea at rest

Nursing Diagnosis 4: Anxiety

Component	Details
Assessment	Verbal expressions, behavioral manifestations, vital sign changes
Goal	Patient will verbalize reduced anxiety and demonstrate relaxed behavior

Interventions:

Intervention	Rationale
Establish therapeutic relationship	Builds trust and rapport
Provide calm, reassuring presence	Reduces fear and anxiety
Explain all procedures and equipment	Reduces fear of unknown
Allow patient to express feelings	Validates concerns
Provide honest, accurate information	Builds trust
Involve family in care	Provides support system
Teach relaxation techniques	Provides coping strategies
Administer anxiolytics if prescribed	Reduces severe anxiety
Minimize environmental stimuli	Promotes rest
Answer call bells promptly	Provides sense of security
Allow for adequate rest periods	Reduces physical stress

Evaluation: Patient verbalizes feeling calmer, demonstrates relaxed body language, vital signs stable

Nursing Diagnosis 5: Activity Intolerance

Component	Details
Assessment	Response to activity, fatigue level, vital signs with activity
Goal	Patient will tolerate progressive activity without adverse cardiac symptoms

Interventions:

Intervention	Rationale
Maintain bed rest during acute phase (first 12-24 hours)	Reduces myocardial workload
Assess vital signs before and after activity	Monitors tolerance
Implement cardiac rehabilitation program	Progressive conditioning
Increase activity gradually	Prevents cardiac strain
Allow rest periods between activities	Reduces fatigue
Assist with ADLs as needed	Conserves energy
Monitor for activity intolerance signs	Early detection of problems
Educate about energy conservation	Promotes independence
Use bedside commode instead of bedpan	Reduces straining
Discontinue activity if adverse symptoms occur	Prevents complications

Activity Progression Protocol:

Day	Activity Level
Day 1-2	Bed rest, passive ROM
Day 2-3	Dangle legs, sit in chair
Day 3-4	Walk in room, bathroom privileges
Day 4-5	Walk in hallway with assistance
Day 5-6	Independent ambulation, stairs

Evaluation: Patient tolerates progressive activity without chest pain, dyspnea, or vital sign abnormalities

Nursing Diagnosis 6: Deficient Knowledge

Component	Details
Assessment	Current knowledge level, learning needs, readiness to learn
Goal	Patient will verbalize understanding of condition, medications, and lifestyle modifications

Interventions:

Intervention	Rationale
Assess readiness to learn	Optimal timing for education
Use appropriate teaching methods	Enhances learning
Explain disease process	Promotes understanding
Review all medications	Ensures medication compliance
Teach warning signs to report	Promotes early intervention
Discuss lifestyle modifications	Reduces risk factors
Provide written materials	Reinforces verbal teaching
Include family in education	Support system involvement
Discuss cardiac rehabilitation	Promotes recovery
Address questions and concerns	Clarifies misunderstandings

Patient Education Topics:

1. Disease Understanding
• What happened to the heart
• Risk factors and prevention
2. Medications
• Names, doses, timing
• Side effects to report
• Importance of compliance
3. Lifestyle Modifications
• Smoking cessation
• Heart-healthy diet
• Exercise program
• Weight management
• Stress reduction
4. Activity Guidelines
• When to resume activities
• Sexual activity guidelines
• Return to work
• Driving restrictions
5. Warning Signs
• Chest pain
• Shortness of breath
• Excessive fatigue
• When to call 911

Evaluation: Patient correctly verbalizes understanding of condition and management plan

Area	Recommendations
Diet	Low sodium (<2g/day), low saturated fat, Mediterranean diet
Exercise	30 minutes moderate activity, 5 days/week (after clearance)
Smoking	Complete cessation, nicotine replacement if needed
Alcohol	Limit to 1 drink/day (women), 2 drinks/day (men)
Weight	BMI <25 kg/m², waist circumference targets
Stress	Stress management techniques, counseling if needed

D. Cardiac Rehabilitation:

• Phase I: Inpatient (education, early mobilization)
• Phase II: Outpatient supervised exercise (6-12 weeks)
• Phase III: Maintenance program

E. Emergency Action Plan:

• Recognition of warning signs
• When to take nitroglycerin
• When to call 911
• Family CPR training

10. COMPLICATIONS TO MONITOR

Early Complications (Within 24-72 hours):

• Arrhythmias: VF, VT, heart blocks
• Cardiogenic shock
• Acute heart failure
• Reinfarction
• Pericarditis

Intermediate Complications (Days to weeks):

• Ventricular aneurysm
• Ventricular septal defect
• Papillary muscle rupture
• Free wall rupture
• Mural thrombus

Late Complications (Weeks to months):

• Dressler's syndrome (post-MI pericarditis)
• Chronic heart failure
• Ventricular remodeling
• Depression/anxiety

11. PROGNOSIS AND OUTCOMES

Factors Affecting Prognosis:

• Time to reperfusion
• Infarct size
• Left ventricular function
• Age and comorbidities
• Compliance with treatment

Key Performance Indicators:

• Door-to-balloon time <90 minutes
• Door-to-needle time <30 minutes
• Aspirin within 24 hours
• Beta-blocker prescribed at discharge
• ACE-I/ARB prescribed at discharge
• Statin prescribed at discharge
• Smoking cessation counseling