Ischemic heart disease (IHD), also known as coronary artery disease (CAD), is a condition characterized by reduced blood flow to the heart muscle due to the narrowing or blockage of coronary arteries. This reduction in blood flow can lead to symptoms such as angina pectoris and, in severe cases, myocardial infarction (heart attack). The primary underlying cause of IHD is atherosclerosis, a condition characterized by the buildup of plaques in the arterial walls. This note will explore angina, myocardial infarction, atherosclerosis, and arteriosclerosis in detail.
 Angina Pectoris
Angina pectoris is a clinical syndrome characterized by episodes of chest pain or discomfort due to transient myocardial ischemia, which occurs when the heart muscle’s demand for oxygen exceeds the supply provided by the coronary arteries.
Types of Angina
1. Stable Angina:
– Occurs predictably with exertion or stress and is relieved by rest or nitroglycerin.
– Caused by a fixed coronary artery stenosis due to atherosclerotic plaques.
2. Unstable Angina:
– Occurs unpredictably, at rest, or with minimal exertion, and is not relieved by rest or nitroglycerin.
– Indicates a high risk of progression to myocardial infarction.
– Often caused by plaque rupture and thrombosis.
3. Variant (Prinzmetal’s) Angina:
– Caused by coronary artery spasm, leading to transient ischemia.
– Can occur at rest and is often unrelated to atherosclerosis.
Symptoms
– Chest pain or discomfort, often described as pressure, tightness, or squeezing.
– Pain may radiate to the shoulders, arms, neck, jaw, or back.
– Shortness of breath, sweating, nausea, and fatigue.
Diagnosis
– Clinical history and physical examination.
– Electrocardiogram (ECG): May show ST-segment changes during episodes.
– Stress testing: Exercise or pharmacologic stress tests to induce ischemia.
– Coronary angiography: Visualizes the coronary arteries and identifies blockages.
Treatment
– Lifestyle modifications: Smoking cessation, weight management, healthy diet, and regular exercise.
– Medications: Nitrates, beta-blockers, calcium channel blockers, antiplatelet agents (e.g., aspirin), statins.
– Revascularization: Percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in severe cases.
 Myocardial Infarction
Myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow to a part of the heart muscle is blocked for a prolonged period, resulting in irreversible damage and death of myocardial cells.
Causes
– Most commonly caused by rupture of an atherosclerotic plaque and subsequent thrombosis in a coronary artery.
– Other causes include coronary artery spasm, embolism, or dissection.
Symptoms
– Severe chest pain or discomfort, often described as crushing or constricting, lasting more than a few minutes.
– Pain may radiate to the arms, neck, jaw, or back.
– Shortness of breath, sweating, nausea, vomiting, dizziness, and palpitations.
– Some patients, particularly women and diabetics, may present with atypical symptoms or silent MI.
Diagnosis
– Clinical history and physical examination.
– Electrocardiogram (ECG): ST-segment elevation or depression, new left bundle branch block (LBBB).
– Cardiac biomarkers: Elevated troponin I or T, creatine kinase-MB (CK-MB).
– Imaging: Echocardiography, cardiac MRI, or coronary angiography.
Treatment
– Immediate treatment: Oxygen, aspirin, nitroglycerin, morphine, and beta-blockers.
– Reperfusion therapy: Primary PCI or thrombolytic therapy to restore blood flow.
– Medications: Antiplatelet agents, anticoagulants, statins, ACE inhibitors, beta-blockers.
– Lifestyle modifications and cardiac rehabilitation.
 Atherosclerosis
Atherosclerosis is a chronic inflammatory disease characterized by the buildup of plaques (atheromas) in the inner lining of arteries, leading to reduced blood flow and the risk of plaque rupture and thrombosis.
Pathophysiology
– Endothelial injury and dysfunction: Caused by factors such as hypertension, hyperlipidemia, smoking, and diabetes.
– Lipid accumulation: Low-density lipoprotein (LDL) cholesterol infiltrates the arterial wall and undergoes oxidation.
– Inflammatory response: Macrophages ingest oxidized LDL, forming foam cells and creating fatty streaks.
– Plaque formation: Smooth muscle cells proliferate and produce extracellular matrix, forming a fibrous cap over the lipid core.
– Plaque instability: Inflammatory cells release enzymes that weaken the fibrous cap, making it prone to rupture.
Risk Factors
– Modifiable: Hypertension, hyperlipidemia, smoking, diabetes, obesity, sedentary lifestyle, unhealthy diet.
– Non-modifiable: Age, gender (male), family history of cardiovascular disease.
Complications
– Coronary artery disease: Angina and myocardial infarction.
– Cerebrovascular disease: Transient ischemic attack (TIA) and stroke.
– Peripheral artery disease: Claudication and critical limb ischemia.
– Aneurysms: Weakening of the arterial wall.
 Arteriosclerosis
Arteriosclerosis is a general term for the thickening and hardening of arterial walls, leading to loss of elasticity. It includes atherosclerosis as a specific type.
Types of Arteriosclerosis
1. Atherosclerosis: Formation of atherosclerotic plaques in large and medium-sized arteries.
2. Arteriolosclerosis: Affects small arteries and arterioles, often associated with hypertension and diabetes.
– Hyaline arteriolosclerosis: Deposition of hyaline material in the vessel wall, leading to thickening and narrowing.
– Hyperplastic arteriolosclerosis: Proliferation of smooth muscle cells, causing concentric thickening and “onion-skin” appearance.
3. Monckeberg Medial Calcific Sclerosis: Calcification of the tunica media of medium-sized arteries, usually without significant luminal narrowing.
Causes
– Similar to those of atherosclerosis, including hypertension, hyperlipidemia, diabetes, and smoking.
– Age-related changes in the arterial wall.
Symptoms and Complications
– Often asymptomatic until significant narrowing or blockage occurs.
– Can lead to complications such as hypertension, ischemic heart disease, stroke, and peripheral artery disease.
Conclusion
Ischemic heart disease is a major health concern worldwide, primarily caused by atherosclerosis and arteriosclerosis. Understanding the mechanisms, risk factors, symptoms, and treatment options for angina pectoris, myocardial infarction, atherosclerosis, and arteriosclerosis is crucial for effective management and prevention. Early detection, lifestyle modifications, and appropriate medical interventions can significantly reduce the morbidity and mortality associated with these conditions.
