Acute Myocardial Infarction

Acute Myocardial Infarction

1. Definition
   Acute Myocardial Infarction (AMI) is the sudden death of heart‑muscle cells caused by an abrupt interruption of blood flow through a coronary artery. It is the clinical manifestation of a heart attack and represents a medical emergency.

2. Synonyms
   Myocardial Infarction, Coronary Thrombosis, Heart Attack – all terms describe the same acute loss of myocardial tissue due to vascular occlusion.

3. Causes / Etiology

• Atherosclerotic plaque rupture – a fatty deposit in the coronary wall breaks open, exposing thrombogenic material. This is the most common trigger for AMI.
• Thrombus formation on ruptured plaque – platelets aggregate and a clot forms, completely blocking the lumen. The clot is the final event that stops blood supply.
• Coronary artery spasm – sudden, intense constriction of a coronary vessel reduces flow even without a clot. Often seen in variant (Prinzmetal) angina.
• Embolism from distant source – a clot or debris travels from another site (e.g., deep‑vein thrombosis) and lodges in a coronary artery. Rare but possible.

4. Types / Classification

• ST‑Elevation Myocardial Infarction (STEMI) – the ECG shows a new, persistent elevation of the ST segment. It indicates a complete occlusion of a major coronary artery, requires immediate reperfusion, and carries a higher early mortality.
• Non‑ST‑Elevation Myocardial Infarction (NSTEMI) – the ECG lacks ST elevation but cardiac enzymes (troponin) are raised. It reflects a partially occluded artery or a smaller area of necrosis; management is urgent but not as time‑critical as STEMI.

5. Pathophysiology / Pathology

• Plaque in a coronary artery becomes unstable and ruptures.
• Subendothelial collagen and lipid core are exposed, triggering platelet adhesion.
• A thrombus rapidly forms, narrowing or occluding the artery.
• Myocardial cells downstream become ischemic because oxygen delivery falls below demand.
• If ischemia persists beyond 20‑30 minutes, irreversible cell death (infarction) begins.
• Necrotic tissue releases intracellular enzymes (troponin, CK‑MB) into the bloodstream, which are detectable on blood tests.

6. Clinical Features

• Central chest discomfort described as pressure, heaviness or burning, lasting more than a few minutes.
• Pain may radiate to the left arm, neck, jaw or back.
• Shortness of breath due to left‑ventricular dysfunction.
• Cold, clammy skin and a feeling of impending doom.
• Light‑headedness or syncope, especially if a serious arrhythmia develops.

7. Complications

Acute complications – life‑threatening arrhythmias (ventricular tachycardia/fibrillation), acute left‑ventricular failure, cardiogenic shock, mechanical rupture of the ventricular wall, papillary‑muscle rupture leading to severe mitral regurgitation.

Chronic complications – post‑infarction ventricular remodeling, formation of a ventricular aneurysm, chronic heart failure, recurrent ischemic events, and post‑myocardial infarction syndrome (pain, anxiety, insomnia).

8. Investigations / Diagnosis

• 12‑lead ECG – identifies ST elevation, new Q waves or other ischemic changes; essential for rapid classification.
• Cardiac biomarkers (troponin I/T, CK‑MB) – rise within hours of cell death and confirm myocardial injury.
• Chest X‑ray – assesses heart size, pulmonary congestion and rules out other thoracic pathology.
• Echocardiography – visualises wall‑motion abnormalities, estimates ejection fraction and detects mechanical complications.
• Coronary angiography – definitive test to locate the occlusion and guide revascularisation.

9. Differential Diagnosis

• Unstable angina – chest pain of similar quality but without troponin rise; ECG changes are transient.
• Pulmonary embolism – sudden dyspnoea and pleuritic chest pain, often with a clear lung field on X‑ray and a characteristic S1Q3T3 pattern on ECG.
• Aortic dissection – tearing chest pain radiating to the back, unequal blood pressures in the arms and a widened mediastinum on X‑ray.

10. Management / Treatment

General management – give supplemental oxygen if saturation is low, keep the patient calm and at rest, and provide analgesia (usually sublingual nitroglycerin or morphine) to relieve pain and reduce myocardial oxygen demand.

Modern medicine treatment – immediate chewable aspirin (300 mg) to inhibit platelet aggregation; a P2Y12 inhibitor (clopidogrel or ticagrelor) added if PCI is planned; beta‑blocker (metoprolol) to lower heart rate and contractility; high‑dose statin to stabilise plaque; anticoagulation with heparin; reperfusion either by primary percutaneous coronary intervention (PCI) or, if unavailable, thrombolytic therapy.

Diet and lifestyle advice – adopt a low‑saturated‑fat, high‑fiber diet to lower cholesterol; engage in regular moderate‑intensity aerobic exercise (150 minutes per week) to improve cardiac reserve; stop smoking to reduce endothelial injury; control blood pressure and diabetes through medication and lifestyle; maintain a healthy weight to lessen cardiac workload.

11. Homeopathic Therapeutics

12. Aconitum napellus

    • Causation: sudden fright, shock or exposure to cold wind.
    • Characteristic symptoms: intense anxiety, restlessness, rapid pulse.
    • Modalities: symptoms improve with fresh air, worsen from heat and tight clothing.
    • Mental state: fear of death, feeling of impending doom.
    • Thirst and appetite: great thirst for cold water, appetite poor.
    • Discharges: dry mouth, scanty urine.
    • Physical generals: pallor, trembling, hyperaemia of the face.
    • Suitable constitution: young, thin, highly nervous individuals.
    • Helps by addressing the acute panic and sudden circulatory collapse that often accompany the onset of a heart attack.

13. Arnica montana

    • Causation: over‑exertion, physical trauma or sudden strain.
    • Characteristic symptoms: soreness, bruising feeling in the chest, throbbing pain.
    • Modalities: better from warm applications, worse from cold.
    • Mental state: feeling of being “blown up”, desire to lie still.
    • Thirst and appetite: thirst for cold water, appetite diminished.
    • Discharges: scanty, dark urine; occasional haematuria.
    • Physical generals: marked tenderness over the heart region, feeling of heaviness.
    • Suitable constitution: robust, outdoors‑working persons who push themselves hard.
    • Helps by relieving the bruising‑type pain and the sense of muscular exhaustion that can follow an infarct.

14. Crataegus monogyna

    • Causation: chronic strain of the heart, hereditary predisposition.
    • Characteristic symptoms: palpitations with a feeling of “fluttering”, chest tightness on exertion.
    • Modalities: better after a light meal, worse after rich food or alcohol.
    • Mental state: anxiety about health, fear of fainting.
    • Thirst and appetite: thirst for cold water, appetite moderate.
    • Discharges: occasional mild cough with frothy sputum.
    • Physical generals: weak pulse, low blood pressure, peripheral coldness.
    • Suitable constitution: middle‑aged, sedentary individuals with a family history of heart disease.
    • Helps by strengthening the myocardium and improving circulation in the early phase after infarction.

15. Digitalis purpurea

    • Causation: long‑standing weakness of the heart, often after repeated attacks.
    • Characteristic symptoms: slow, irregular pulse, visual disturbances (yellow‑green halos).
    • Modalities: better in a warm room, worse from exertion and cold.
    • Mental state: confusion, forgetfulness, desire to lie down.
    • Thirst and appetite: thirst for warm drinks, appetite poor.
    • Discharges: nausea, occasional vomiting.
    • Physical generals: cyanosis of lips, cold extremities, edema of ankles.
    • Suitable constitution: elderly, frail patients with chronic cardiac insufficiency.
    • Helps by supporting the weakened ventricular contractility and controlling arrhythmias.

16. Kali carbonicum

    • Causation: mental stress, over‑work, suppressed emotions.
    • Characteristic symptoms: crushing chest pain, feeling of a heavy weight on the heart.
    • Modalities: better in the open air, worse from tight clothing and cold drinks.
    • Mental state: anxiety, fear of loss, feeling of being “out of breath” mentally.
    • Thirst and appetite: great thirst for cold water, appetite reduced.
    • Discharges: dry cough, scanty sputum.
    • Physical generals: weak pulse, low blood pressure, cold hands and feet.
    • Suitable constitution: people who are habitually over‑exerted, often teachers or clerks.
    • Helps by calming the nervous over‑activity that aggravates coronary spasm.

17. Natrum muriaticum

    • Causation: emotional upset, grief, suppressed tears.
    • Characteristic symptoms: burning chest pain that improves with rest, feeling of “tightness”.
    • Modalities: better in cool, dry air; worse from heat, emotional excitement.
    • Mental state: introverted, prefers solitude, holds grudges.
    • Thirst and appetite: thirst for salty water, appetite moderate.
    • Discharges: dry mucous membranes, occasional nasal discharge.
    • Physical generals: dry skin, brittle nails, tendency to develop varicose veins.
    • Suitable constitution: individuals who are sensitive, often women with a history of emotional trauma.
    • Helps by addressing the underlying emotional factors that can precipitate coronary events.

18. Nux vomica

    • Causation: excess stimulants (caffeine, alcohol), over‑indulgence, irritability.
    • Characteristic symptoms: sharp, stabbing chest pain that radiates to the jaw, aggravated by lying on the left side.
    • Modalities: better after vomiting, worse after rich, spicy food.
    • Mental state: irritable, impatient, feels “under pressure”.
    • Thirst and appetite: thirst for hot drinks, appetite strong but disturbed.
    • Discharges: frequent belching, occasional diarrhoea.
    • Physical generals: tremulous hands, high blood pressure, restless legs.
    • Suitable constitution: hardworking, ambitious persons who neglect rest.
    • Helps by correcting the hyper‑stimulant state that predisposes to coronary spasm and thrombosis.

19. Valeriana officinalis

    • Causation: chronic nervous tension, insomnia, over‑work.
    • Characteristic symptoms: dull, heavy chest pain with a feeling of “pressure” that worsens at night.
    • Modalities: better in a quiet, dark room; worse from noise and bright light.
    • Mental state: anxiety, fear of death, desire to sleep but unable to.
    • Thirst and appetite: thirst for warm water, appetite poor.
    • Discharges: dry mouth, occasional night sweats.
    • Physical generals: slow, weak pulse, cold extremities, slight edema.
    • Suitable constitution: people who are nervous, often students or clerical workers.
    • Helps by calming the nervous system and reducing the sympathetic drive that increases cardiac workload.

20. Prognosis
    If reperfusion is achieved within the first few hours, survival rates improve markedly and many patients regain near‑normal cardiac function. Larger infarcts, delayed treatment, advanced age, diabetes or renal failure worsen the outlook and increase the risk of heart failure or recurrent events. Early rehabilitation and strict risk‑factor control are essential for a favorable long‑term prognosis.

21. Prevention
    Regular aerobic exercise improves coronary endothelial function and reduces plaque formation. A diet low in saturated fat and cholesterol lowers serum lipids, decreasing the chance of plaque rupture. Controlling hypertension, diabetes and quitting smoking remove major modifiable risk factors, thereby markedly reducing the incidence of a first or recurrent myocardial infarction.

22. Diet
    Recommended foods – fresh fruits, vegetables, whole‑grain cereals and legumes; these provide fiber, antioxidants and low‑density lipids, helping to keep arterial walls healthy.

Avoided foods – fried items, red meat, full‑fat dairy and sugary beverages; they raise LDL cholesterol and promote atheroma growth, increasing the likelihood of arterial blockage.