CARDIOVASCULAR PATHOLOGY

These comprehensive notes cover MBChB-level cardiovascular pathology, focusing on common diseases affecting the heart and blood vessels. Topics include atherosclerosis, ischemic heart disease, valvular disorders, cardiomyopathies, and congenital anomalies, providing detailed information essential for examination preparation. This document outlines definitions, risk factors, pathogenesis, morphology, clinical manifestations, and complications for a thorough understanding of each condition. Key Points Atherosclerosis is a chronic inflammatory disease of arteries, driven by endothelial injury and lipid accumulation, leading to the formation of fibrofatty plaques and significant cardiovascular complications. Ischemic heart disease, primarily caused by coronary atherosclerosis, manifests as angina or myocardial infarction, with distinct pathological changes over time and various life-threatening complications. Valvular heart diseases, such as those arising from rheumatic fever or degenerative calcification, involve stenosis or regurgitation, profoundly affecting cardiac function and often leading to heart failure or emboli. Cardiomyopathies are primary myocardial diseases, classified into dilated, hypertrophic, and restrictive types, each presenting with unique structural and functional abnormalities that can result in heart failure, arrhythmias, or sudden death. Congenital heart defects range from simple shunts to complex structural anomalies, impacting blood flow and oxygenation, necessitating early diagnosis and often surgical intervention to prevent long-term complications like Eisenmenger syndrome. Detailed Notes TOPIC 1: ATHEROSCLEROSIS & ARTERIOSCLEROSIS Definitions Arteriosclerosis – General term for hardening and loss of elasticity of arterial walls Atherosclerosis – Most important form; a chronic inflammatory disease of large and medium arteries characterized by formation of atheromatous plaques in the intima Risk Factors Non-modifiable: Age (men 45, women 55) Male sex Family history/genetics Race Modifiable: Hypertension Hyperlipidemia (high LDL, low HDL) Diabetes mellitus Cigarette smoking Obesity Sedentary lifestyle Homocysteinemia Pathogenesis — Response to Injury Hypothesis 1. Endothelial injury/dysfunction caused by: hypertension, smoking, hyperlipidemia, toxins 2. Increased permeability → LDL enters intima → oxidized to ox-LDL 3. Endothelium expresses adhesion molecules (VCAM-1, ICAM-1) 4. Monocytes adhere and migrate into intima → become macrophages 5. Macrophages engulf ox-LDL → become foam cells → fatty streak (earliest lesion, reversible) 6. Macrophages release cytokines and growth factors → stimulate smooth muscle cell (SMC) migration from media to intima 7. SMCs proliferate and produce extracellular matrix (collagen, proteoglycans) 8. Formation of fibrofatty plaque (atheromatous plaque) Morphology of an Atheromatous Plaque Fibrous cap – SMCs and dense collagen (overlying the lesion) Necrotic core – lipid debris, foam cells, cholesterol crystals, dead cells Shoulder region – active inflammation (macrophages, T cells) Neovascularization at base Vulnerable (Unstable) Plaque Thin fibrous cap Large lipid core Many inflammatory cells Prone to rupture → thrombosis → acute coronary syndrome Progression of Atherosclerosis 1. Normal artery 2. Endothelial dysfunction 3. Fatty streak – flat yellow intimal lesion; foam cells; reversible 4. Fibrofatty plaque – raised yellow-white lesion; fibrous cap + lipid core 5. Complicated plaque – calcification, ulceration, thrombosis, hemorrhage Complications of Atherosclerosis Myocardial infarction (coronary arteries) Stroke (cerebral/carotid arteries) Peripheral arterial disease (lower limbs) Aortic aneurysm (aorta) Mesenteric ischemia (mesenteric arteries) Renal artery stenosis → renovascular hypertension Types of Arteriosclerosis 1. Hyaline arteriolosclerosis – Homogeneous pink hyaline thickening of arteriolar walls; seen in benign hypertension and diabetes mellitus 2. Hyperplastic arteriolosclerosis – "Onion-skin" concentric laminated thickening; seen in malignant (severe) hypertension; causes marked luminal narrowing 3. Monckeberg medial calcific sclerosis – Calcification of the media of muscular arteries; does NOT narrow lumen; not clinically significant usually; seen in elderly --- TOPIC 2: ISCHEMIC HEART DISEASE (IHD) Definition A group of conditions resulting from imbalance between myocardial oxygen supply and demand , most commonly due to coronary atherosclerosis. Causes Coronary atherosclerosis ( 90% of cases) Coronary vasospasm ( Prinzmetal angina ) Thromboembolism Coronary artery anomalies Severe anemia Aortic stenosis (reduced coronary perfusion) Types of IHD 1. Stable (Chronic) Angina Fixed atherosclerotic stenosis ( 70% occlusion) Predictable chest pain on exertion, relieved by rest or nitrates No myocardial necrosis Caused by demand exceeding supply 2. Unstable Angina Part of Acute Coronary Syndrome (ACS) Plaque rupture + partial thrombosis Chest