PATH 3810 Cardiovascular System 2023 Final Exam Paper PDF

9/25/2023 Shock • Shock is the final common pathway for a number of potentially lethal events including… • severe hemorrhage extensive trauma or burns, extensive myocardial infarction, massive pulmonary embolism, microbial sepsis • Shock gives rise to systemic hypoperfusion • Key pathophysiologic...

9/25/2023 Shock • Shock is the final common pathway for a number of potentially lethal events including… • severe hemorrhage extensive trauma or burns, extensive myocardial infarction, massive pulmonary embolism, microbial sepsis • Shock gives rise to systemic hypoperfusion • Key pathophysiologic event regardless of cause • Results from either reduced cardiac output or reduced circulating blood volume • End results of shock are hypotension, impaired tissue perfusion (i.e. tissue hypoperfusion), and cellular hypoxia 118 Categories of Shock • 3 general categories of shock • Cardiogenic shock results from failure of cardiac pump • Myocardial infarction, ventricular arrythmias, outflow obstruction • Hypovolemic shock results from loss of blood or plasma volume • Hemorrhage, extensive burns • Septic shock is caused by microbial infection • Most commonly gram‐negative infections (endotoxic shock) • Less common are neurogenic and anaphylactic shock • Neurogenic shock results from loss of vascular tone leading to peripheral blood pooling • Anaphylactic shock results from systemic vasodilation and increased vascular permeability mediated by IgE hypersensitivity reaction 119 Morphology of Shock • Cellular and tissue changes induced by shock are essentially those of hypoxic injury due to hypoperfusion and thrombosis of microvasculature • Shock is characterized by failure of many organ systems (multiorgan system failure); morphologic changes may appear in any tissue, particularly the brain, heart, kidneys, adrenal glands and GI tract • Septic shock results from host innate immune response to bacterial or fungal cell molecules; mediated by TLRs causing widespread (i.e. systemic) production of cytokines, TNF and IL‐1, leading to system‐wide endothelial and leukocyte activation • Clinical triad of septic shock is hypotension, DIC and metabolic disturbances Disseminated intravascular coagulopathy 120 40 9/25/2023 Degenerative diseases • Hypertensive vascular disease • morphology: arteriosclerosis • important consequences and collateral effects: coronary heart disease, cerebral aneurysm rupture, cardiac hypertrophy, aortic dissection and renal failure • Human and veterinary medicine High osmotic pressure in the blood vessels • Blood pressure is function of: • Cardiac output: function of blood volume, dependent on sodium (Na) concentration • Peripheral resistance: function of caliber and tone of arterioles predominantly, neurologic and hormonal Means small blood vessels play important role in regulation peripheral resistance and the blood pressure • Kidney and adrenal gland regulation 121 Degenerative diseases Hypertensive vascular disease 122 Degenerative diseases Hypertensive vascular disease Hyperplastic arteriosclerosis Hyaline arteriosclerosis Hyaline is protein like material that can deposit in the wall and it is homogenous. Blood vessel thickened. Cannot see tunica media , just seeing hypertensive effect. 123 Multiple layer of smooth muscle -onion peel effect. 41 9/25/2023 Degenerative diseases: Atherosclerosis • Characterized by intimal lesions called atheromas that protrude into vascular lumina • Consists of raised lesion with a soft, yellow, grumous core of lipid (cholesterol) covered by a firm, white fibrous cap • Obstruct blood flow and weaken underlying media and can rupture leading to vessel thrombosis • Atherosclerosis is a slowly evolving lesion and can require decades to become significant • Major consequences include myocardial infarction (heart attack), cerebral infarction (stroke), aortic aneurysms, and peripheral vascular disease Lodge in coronary vessels and cause infarction. 124 This is Atheroma! Know this! Macrophages, cholesterol crystals, lymphocytes,collagen, fibroblasts proteoglycans Smooth muscle proliferating, all causing thickening and destruction of tunica media and intima sometimes 125 Degenerative diseases Atherosclerosis The coronary vessels. Fibrous plaques Of a Mild atherosclerosis Pathologic basis of veterinary disease Dog with hyperlipidemia 126 42 9/25/2023 Full blown atherosclerosis. Roughened surface area: hypercoagulativity, blood pressure, endothelial damage/roughened 127 Hypercoagulability, Blood pressure Endothelial damage Atherosclerotic plaques, trichrome stain to stain Connective tissue staining blue, smooth muscle pink Cholesterol crystals Macrophages, cholesterol crystals, fibroblasts Media and intima is almost obliterated 128 Degenerative diseases Aneurysms and dissections • Aneurysm is a localized abnormal dilation of a blood vessel or the heart – True aneurysm involves all three layers of arterial wall – False aneurysm is a breach in the vascular wall leading to extravascular hematoma • Dissection arises when blood enters the wall of the artery, as a hematoma dissecting between its layers 129 One sided Both sided 43 9/25/2023 Degenerative diseases: Aneurysms and dissections • Causes of aneurysms: • atherosclerosis, infection, congenital 130 131 Degenerative diseases Aneurysms and dissections • Aortic Dissection – Blood splays apart the laminar planes of the media to form a blood filled channel within the aortic wall – In human medicine often secondary to hypertension – Most common form in animals, various developmental or nutritional risk factors implicated One step before aortic dissection – Cystic medial degeneration: loss of smooth muscle cells, fragmentation or mineralization of elastic fibers – Location of intimal tear: ascending aorta in most cases – Can extend along the aorta Pathologic basis of veterinary disease Pig with copper deficiency, pulmonary artery dissection 132 44 9/25/2023 Degenerative diseases Aneurysms and dissections Degenerating smooth muscle Elastic fibers erratic Cystic medial degeneration Medial dissection Blood pooling in walls of major arteries 133 Inflammatory diseases: Vasculitis Pathogenic mechanisms Immune-mediated inflammation: noninfectious vasculitis, ! Microbial agents can be implicated secondarily Invasion of vascular walls by infectious pathogens: infectious vasculitis Nodular , proliferating Rat Immune-mediated vasculitis: HSIII type, immune complex associated • Polyarteritis Nodosa (PAN) • Systemic, small to medium caliber muscular arteries • Eg: associated with hepatitis B infection, HBAg-HBAb complexes • Morphology: • Acute: necrosis, cellular inflammation, fibrin • Chronic: fibrosis, proliferative inflammation 134 Tumors of blood vessels • Benign tumors – Hemangioma‐ increase numbers of normal or abnormal vessels filled with blood – Lymphangioma‐ lymphatic analogue of hemangiomas – Glomangioma‐ arise from modified SMCs of glomus body, a arteriovenous structure involved in thermoregulation – Bacilliary angiomatosis‐ opportunistic infection in immunocompromised persons that manifests as vascular proliferations 135 45 9/25/2023 Tumors of blood vessels Capillary variant Cavernous variant 136 Tumors of blood vessels • Intermediate grade (low grade malignant tumors) – Kaposi Sarcoma – common in AIDS patients, presents with red to purple skin plaques – Hemangioendothelioma • Malignant Tumors – Angiosarcoma – malignant endothelial neoplasms – Hemangiopericytoma – rare tumors derived from pericytes‐ myofibroblast like cells that are normally arranged around capillaries and venules 137 Congenital heart disease • Abnormalities of heart or greater vessels that are present at birth: 1% of live births • Causes: congenital infection (rubella virus), genetic factors • Divided into 3 major groups • Malformations causing left to right shunt • Malformations causing right to left shunt • Malformations causing obstruction • Shunt is an abnormal communication between chambers or blood vessels • Obstructive congenital heart disease are developmental anomalies that obstruct vascular flow by narrowing chambers, valves or major blood vessels • Atresia is a complete obstruction 138 46 9/25/2023 Congenital heart disease • Left to right shunt: septal defects & patent ductus arteriosus • Most common congenital cardiac defects • Initially cause left to right shunt due to low pressures in pulmonary circulation and right side of heart • Increase pulmonary blood flow result in right ventricular hypertrophy Most common: patent ductus Wall of right ventricle will get very hypertrophic 139 Congenital heart disease • Left to right shunt • With time pulmonary hypertension and right ventricular hypertrophy can cause a reverse flow and cause cyanosis • Atrial Septal Defects • Failure of closure of foramen ovale after birth • Patent Ductus Arteriosus • Permits blood flow from aorta (bypassing lungs) to pulmonary artery during intrauterine life 140 Congenital heart disease • Left to right shunt • Ventricular Septal Defects 141 47 9/25/2023 Congenital heart disease • Right to left shunt • Cyanosis because pulmonary circulation is bypassed and poorly oxygenated blood enters systemic circulation • Tetralogie de Fallot • Most common form • Ventricular Septal Defects (VSD) • Obstruction to right ventricular outflow tract • Aorta that overrides the VSD • Right ventricular hypertrophy 142 143 144 48 9/25/2023 145 Diseases of the heart • Heart failure aka congestive heart failure (CHF) – heart is no longer able to pump blood at rates that meet the requirements of metabolizing tissues • Forward failure‐ inadequate cardiac output • Backward failure‐increased congestion of venous circulation • Can affect predominantly left side or right side, or both sides of heart 146 Left‐sided heart failure • Most common causes: Ischemic Heart Disease, systemic hypertension, mitral or aortic valve disease, primary diseases of myocardium • Morphology: hypertrophy, dilation, fibrosis, atrial thrombi • Extracardiac lesions: pulmonary congestion and edema • Dyspnea (breathlessness), cardiomegaly, tachycardia, a third heart sound, and fine rales at lung bases produced by respirations through edematous alveoli 147 49 9/25/2023 Right‐sided heart failure • Most common cause is left ventricular failure, with associated pulmonary congestion and elevation in pulmonary and arterial pressure • Other causes: pulmonary hypertensive diseases, pulmonary valvular disease • Right ventricular hypertrophy and dilation • Pulmonary congestion and left ventricular hypertrophy are present or absent • Systemic and portal venous congestion, with hepatic and splenic enlargement, peripheral edema, pleural effusion, and ascites 148 Ischemic heart disease • Degenerative diseases • Very prevalent in humane medicine • Most often due to reduction in coronary blood flow caused by obstructive atherosclerotic disease • IHD is a group of related syndromes resulting from myocardial ischemia • Clinical manifestations are direct consequence of insufficient blood supply to the heart • 4 basic clinical syndromes • • • • Angina pectoris Acute myocardial infarction (MI) Chronic IHD Sudden cardiac death (SCD) 149 Ischemic heart disease • Myocardial infarction • aka Heart Attack is necrosis of heart muscle resulting from ischemia • Most caused by acute coronary artery thrombosis> Coronary artery occlusion • Myocardial Response to Ischemia • Within seconds, anaerobic glycolysis> decrease production ATP, and accumulation of noxious breakdown products (lactic acid) • Within 1 minute Loss of contractility • Reversible ultrastructural changes • 20‐40 minutes: Irreversible ultrastructural changes and myocyte death • Ischemia also contributes to arrhythmias 150 50