A significant factor that may prevent or diminish the myocardial damage is the development of the Collateral circulation through anastomotic channels over a period of time.
In developed countries like USA, acute Myocardial infarction accounts for 10 to 25% of all deaths. Due to dominant etiologic role of coronary atherosclerosis in acute myocardial infarction, the incidence of acute MI correlates well with the incidence of atherosclerosis in a Geographic area.
Acute Myocardial infarction may Virtually occur at all ages ,though the incidence is higher in the elderly. About 5% of heart attacks occurs in young people under the age of 40 years, particularly in those who with major risk factors to develop atherosclerosis like hypertension, Diabetes mellitus, cigarette smoking and dyslipidemia including family Hypercholesterolemia.
Males throughout their life are at a significantly higher risk of developing acute Myocardial infarction as compared to females. women during reproductive period have markedly low incidence of acute Myocardial infarction.
what causes a heart attack
Etiopathogenesis or pathophysiology of Myocardial infarction-
1. myocardial ischemia
Diminished coronary blood flow
increased myocardial demand. example: exercise, emotions.
2.Hypertrophy of the heart without simultaneous increase of coronary blood flow.
3.Role of platelets- rupture of an atherosclerotic plaque exposes the some endothelial collagen to platelets which undergo aggregation, activation and release reaction.
They may give rise to emboli or initiate thrombosis.
4.Acute plaque rupture
5. Non-atherosclerotic causes
About 10% of cases of acute Myocardial Infarction are caused by non- atherosclerotic factors such as coronary vasospasm, Arthritis, coronary arterial stenosis, embolism, thrombotic diseases, trauma and outside compression.
Type of infarcts
1.Full-thickness- transmural: when they involve the entire thickness of the ventricular wall.
2.Sub-endothelial or laminar: when they occupy the inner sub endocardial half of the myocardium
According to the age of infarcts:
They are of two types
1.Newly formed infarcts
2.Advanced infarcts called as old, healed, organised.
Diagnosis of myocardial infarction or heart attack
clinical features of Myocardial Infarction or Heart attack)
(sign and symptoms of Myocardial infarction or Heart attack)
1.Pain
2.indigestion
3.Apprehension
4.Shock
5.Oligouria
6.Acute pulmonary oedema
7.Low grade fever
Myocardial Infarction ECG
ECG of Myocardial infarction- changes are one of the most important parameters. most characteristic change is St segment elevation in acute Myocardial Infarction other changes include T wave inversion and appearance of wide deep Q waves.
Serum cardiac markers for Myocardial infarction or Heart attack
1.Creatine phosphokinase
2.Lactate dehydrogenase
3.Cardiac specific troponins
4.Myoglobin
Complications of myocardial infarction or Heart attack
Only 10 to 20% cases do not develop major complication and recover. The remainder 80 to 90% cases develop one or more major complication. some of which are fatal.
1.Arrhythmia
2.Congestive heart failure
3.Cardiogenic shock
4.Mural thrombus
5.Thromboembolism
6.Rupture of heart : (5% cases )
7.Pericarditis
8.Aneurysm
9.Post myocardial infarction syndrome
Treatment of Myocardial infarction
(Treatment of Heart attack)
Permanent treatment of myocardial infarction is Angioplasty or surgical procedure or Bypass surgery for myocardial infarction or heart attack.
Drugs for myocardial Infarction or Heart attack
Nitroglycerin
Beta blockers
Anti-platelet drugs
Anticoagulant
Antianginal
ACE inhibitors
