Myocardial Infarction / Heart Attack – At A Glance

Acute coronary syndrome is a term that encompasses both unstable angina and myocardial infarction (MI)

MI, also known as “heart attack,” is the death of cardiac muscle due to prolonged severe ischemia.

Risk Factors Of MI

A. Non modifiable factors
       1. Age
       2. Sex
       3. Genetics
B. Potentially modifiable
       1. Hyperlipidaemia
       2. Hypertension
       3. Cigarette smoking
       4. Diabetes mellitus
C. Other risk factors
       1. Low physical activities
       2. Competitive stressful life (Type A personality)
       3. Obesity
       4. Use of OCP
       5. Hyperuricaemia
       6. High carbohydrate intake
       7. Infectious agents (CMV, Clamydia pneumoniae) 
       8. Post menopausal estrogen deficiency
       9. Use of alcohol
       10. Hardened unsaturated fat intake 

Management Of MI

A. Clinical features
       1. Prolonged cardiac pain – Chest, throat, arms, epigastrium or back
       2. Anxiety and fear of impending death
       3. Nausea and vomiting
       4. Breathlessness
       5. Collapse/syncope

B. On examination 
       1. Signs of sympathetic activation: pallor, sweating, tachycardia
       2. Signs of vagal activation: vomiting, bradycardia
       3. Signs of impaired myocardial function
                   a. Hypotension, oliguria, cold peripheries
                   b. Narrow pulse pressure
               c. Raised JVP
                   d. Third heart sound
                   e. Quiet first heart sound
                   f. Diffuse apical impulse
                   g. Lung crepitations
       4. Signs of tissue damage: fever
       5. Signs of complications: e.g. mitral regurgitation, pericarditis

C. Investigations
       1. ECG 
             Hyperacute T wave
             ST elevation, followed by T wave inversion 
             Pathological T wave
       2. Cardiac enzymes – Elevated
             Creatine phosphokinase-MB 
       3. Cardiac markers – Elevated
             Troponin I
             Troponin T
       4. CBC
             Raised ESR,  C-reactive protein
       5. Lipid profile
       6. Blood glucose level
       7. Urea, creatinine & electrolytes 
       8. Chest X-Ray
             Pulmonary oedema
       9. Echocardiography

D. Treatment
       1. Hospitalization of the patient
       2. Complete bed rest
       3. High flow of oxygen inhalation (2 – 4 L/min by nasal cannula)
       4. To relieve pain
             Morphine 5 – 10mg  + antiemetics given IV
       5. Crush & chew aspirin 300mg and clopidogrel 300mg oral gel
       6. Thrombolytic therapy – Streptokinase / Alteplase
       7. Primary percutaneous coronary intervention (PCI)

Monitoring Of A Patient With MI

1. Diet : Liquid diet
2. 24 hours ECG monitoring
3. Cardiac enzymes
4. 12 lead ECG, daily
5. Check pulse, blood pressure, temperature, respiratory rate is done hourly
6. Auscultation of heart lungs every 4 hourly
7. Monitoring of fluid intake & output chart

Complications Of MI

A. Early
       1. Cardiac arrhythmia 
              Ventricular ectopics 
              Ventricular fibrillation 
              Ventricular tachycardia
       2. Cardiogenic shock 
       3. Cardiac failure (LVF, CCF)
       4. Cardiac temponade 
       5. Thromboembolism 
       6. Mitral regurgitation (Due to rupture of chordae tendineae)
       7. VSD (Due to rupture of interventricular septum)

B. Late 
       1. Ventricular aneurysm  
       2. Postmyocardial infarction syndrome 
       3. Frozen shoulder 
       4. Postinfarct angina 

Discharge Criteria Of MI

1. Advice the patient to alter the risk factors
2. Reassurance of the patient 
3. Discharging drugs
       ACE inhibitors
       Beta blockers
4. Advice the patient to do coronary angiogram, exercise Tolerance Test (ETT)

Contraindications Of Streptokinase

1. Recent surgery (6 months)
2. Recent stroke (6 months)
3. Active internal bleeding (Bleeding peptic ulcer)
4. Bleeding disorders
5. CNS damage or neoplasm
6. Proliferating diabetes retinopathy 
7. Aortic dissection  
8. Transient ischemic attack (6 months) 
9. Pregnancy 
10. Infective endocarditis 
11. Recent trauma 

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