Angina pectoris & Myocardial infarction (MI)

Content

•       Angina pectoris

•       Myocardial infarction

Objectives
 

At the end of this PDF Notes, student will be able to

•        Explain the etiology involved in angina pectoris and myocardial infarction

•        Discuss the pathogenesis of angina pectoris and myocardial infarction

•        Describe the complications associated with angina pectoris and Myocardial infarction

Angina pectoris

•       Discomfort due to transient myocardial ischemia

•       Heart muscle does not receive enough blood (nutrient & O₂) resulting in chest pain

Etiology of Angina Pectoris

•       Atherosclerosis of large coronary arteries

•       Heart valve disease

•       Thickening of heart muscles

•       Coronary artery spasm

•       Hypertension

Symptoms of Angina Pectoris

•       Gripping of central chest pain

•       ↑ shortness of breath on exercise

•       Sense of heaviness or numbness in the arm, shoulder, elbow or hand usually on the left side

•       Constricting sensation in the throat

•       Mild ache to severe pain

•       Sweating and fear

Pathogenesis and Types of Angina

•       Imbalance between myocardial oxygen demand and supply

Stable/ Typical/ Exertional/ Classical Angina

•       Provoked by physical exertion

•       Heaviness, squeezing and sensation of constriction in the chest

•       Pain subsides on resting

•       Depression in ST segment of ECG

•       No elevation in the blood enzyme level if no myocardial injury

Variant/ Prinzmetal Angina

•       Pain at rest

•       No relationship with physical activity

•       Occur due to coronary artery spasm

•       Spasm – due to release of vasoconstrictor by mast cells in coronary artery

•       Attacks are painful, occur between midnight & daily morning

•       ST segment elevation in ECG

•       Patient respond well to vasodilator like nitroglycerine

Unstable/ Atypical/Cresendo/ Preinfarction Angina or Acute coronary insufficiency

•       Frequent onset of pain for longer duration

•       Occurs often at rest

•       Indication of myocardial infarction

Microvascular angina

•       Chest pain , no apparent coronary artery damage

•       Poor functioning of blood vessels  of heart, arm or legs

•       May occur during exercise or at rest

Myocardial infarction

•       Myocardial infarction / Heart attack results from complete obstruction to blood flow in the coronary artery

•       Imbalance in supply and demand of O₂ to myocardium

•       Underlining cause – coronary artery disease

Symptoms of myocardial infarction

•       Severe chest pain

•       Sweating

•       Chest pain radiating through jaw, shoulder, arms and back

•       Epigastric discomfort with or without nausea/ vomiting

•       Sproathy and blood stained sputum

•       Dizziness, weakness, Anxiety

•       Irregular heart beat

•       Heart burn & indigestion

Etio-pathogenesis of Myocardial infarction

Atherosclerotic causes

•       Accounts for 75% of cases

•       Fatty streak deposits on the coronary artery

•       Endothelium develop into an atherosclerotic
plague depending on the presence of risk factors

•       Risk factors – HT, DM, Smoking, Hyperlipidemia

•       Plaque progression, proliferation and
disruption of integrity of blood vessel

•       Results in narrowing off coronary artery &
MI

Non atherosclerotic causes

•       Accounts for 10% of the causes of MI

•       Coronary vasospasm

•       Inflammation of arteries

•       Coronary embolism

•       Development of thrombosis

•       Injury

Complications of Myocardial Infarction

•       Cardiac arrhythmia

•       Congestive heart failure

•       Cardiogenic shock

•       Rapture of heart

•       Mural thrombosis

•       Thromboembolism

Summary

•       Angina is the discomfort due to transient myocardial ischemia where heart muscle does not receive enough blood (nutrient & O₂) resulting in chest pain

•       Myocardial infarction / Heart attack results from complete obstruction to blood flow in coronary artery

•       Causes of angina and MI  include Atherosclerosis of large coronary arteries, heart valve disease, thickening of heart muscles, coronary artery spasm, hypertension

•       Occurs mainly due to the imbalance in supply and demand of O₂ to myocardium

Also, Visit: Pathophysiology Notes