Circulatory Disorders PDF

Circulatory disorders Contents: ischemia- infarction- thrombosis- embolism- edema- gangrene- DIC Target students: 301- FHB 102- Dent 202 Final term BY: PROF. MAHMOUD TAG  Ischemia An inadequate blood supply to an organ or part of the body. It leads to hyp...

Circulatory disorders Contents: ischemia- infarction- thrombosis- embolism- edema- gangrene- DIC Target students: 301- FHB 102- Dent 202 Final term BY: PROF. MAHMOUD TAG  Ischemia An inadequate blood supply to an organ or part of the body. It leads to hypoxia, failure to remove waste products or malnutrition with reversible cell injury, intracellular accumulations or necrosis.  Raynaud's disease is a rare disorder of the blood vessels, usually in the fingers and toes. It causes the blood vessels to narrow when you are cold or feeling stressed. When this happens, blood can't get to the surface of the skin and the affected areas turn white and blue. Raynaud's disease Claudication: a condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries.  Angina Ischemia of the coronary artery leads to angina pectoris. It is a type of chest pain caused by reduced blood flow to the heart. Angina is a symptom of coronary artery disease. Angina pain is often described as squeezing, pressure, heaviness, tightness or pain in the chest. Angina  Varicose veins and ulcer Ischemia of the skin of lower limbs in varicose veins leads to varicose ulcer. Varicose veins are swollen, dilated, tortuous and enlarged veins that usually occur on the legs and feet. It is due to incompetent valves of veins Varicose veins and ulcer  Infarction: It is necrosis of tissues due to cut of blood supply (complete prolonged ischemia). Types of infarction: A. Red or hemorrhagic infarction: Sites: lung and intestine (loose texture organs with double blood supply and venous cut first). It is infarction which remains red due to increased blood content in these organs. Blood escapes from the damaged capillaries and lies free in the infarct area. B. Pale infarction: Sites: heart, kidney and spleen (solid organs and arterial cut first). Usually starts as red then the blood is gradually removed and the infarct area becomes pale in color. C. Soft infarction: (liquefactive necrosis) Site: the central nervous system which has abundant lysosomal enzymes released from microglial cells or necrotic tissue.  Infarction Infarction kidney Infarction kidney Myocardial infarction  Infarction Infarction lung Infarction lung  Infarction Infarction small intestine Infarction small intestine  Strangulated hernia Strangulated hernia: it is due to obstruction of blood vessels of the herniated loop while passing through narrow opening.  Volvulus Volvulus: it is due to twisting of intestinal loop and obstructing the blood vessels passing in its mesentery.  Intussusception Intussusception: it is due to invagination of a loop of intestine into another one.  Virchow's triad (Causes of thromboembolism) Hypercoagulability: caused by: - Increase viscosity of blood in dehydration and malignant tumors. - Treatments for cancer: radiation and chemotherapy - Increase in the number and adhesive power of the platelet. - Decrease heparin. - Genetic deficiencies or autoimmune disorders. Endothelial cell injury: caused by atherosclerosis, surgery, pressure, trauma or inflammation of the artery. Disturbed blood flow: (Stagnation of blood or venous stasis) - Leg veins as post-operative complication or after childbirth or sitting on a long airplane flight. - Chronic venous congestion as in heart failure and atrial fibrillation. - Acute inflammation. - Aneurysm (localized dilatation of an artery or heart) and varicose veins.  Causes of thrombosis Atherosclerosis Aneurysm  Causes of thrombosis Varicose vein  Causes of thrombosis Acute inflammation  Causes of thrombosis Increase Platelet Increase viscosity  Causes of thrombosis Heart failure and AF After child birth Pathogenesis of thrombosis  Pathogenesis of thrombosis: 1- After vascular injury, platelets exposed to ECM constituents (collagen, proteoglycan, fibronectin and adhesive glycoproteins) 2- Platelets- ECM adhesion is mediated through von Willebrand factor (vWF) which acts as a bridge between platelets receptors. 3- Platelet granule secretions (release reaction): alpha granules are secreted and contain coagulation factors and growth factors. Delta granules contain ADP, calcium and vasoactive amines. 4- Platelet aggregation helped by expression of surface phospholipids complex which provide a site for calcium deposition. 5- Erythrocytes and leukocytes also aggregate in hemostatic plug. Leukocytes adhere to platelets via P- selectin and contribute to inflammatory response occur with thrombus. 6- Lines of Zahn are alternating layers of platelets with attached fibrin and RBCs. 7- The thrombus is attached to the vessel wall. Fate of thrombus: 1- Dissolution: the thrombus may be removed by fibrinolytic activity. 2- Propagation: the thrombus may accumulate more platelets and fibrin leading to blood vessel obstruction. 3- Embolization: a- Detachment of non-infected embolus leading to infarction. b- Detachment of infected embolus leading to pyemia. 4- Organization and recanalization: the thrombus may induce inflammation and fibrosis and may eventually become recanalized. 5- Calcification (phlebolith). Types of thrombosis: 1- Thrombosis in veins: A) Phlebothrombosis: it is thrombosis in veins without inflammation. B) Thrombophlebitis: thrombosis of veins due to inflammation C) Deep vein thrombosis (DVT): is the formation of a thrombus within a deep vein. It most commonly affects leg veins, such as the femoral vein. D) Budd-Chiari syndrome: is the blockage of the hepatic vein or the inferior vena cava. This form of thrombosis presents with abdominal pain, ascites and hepatomegaly. 2- Thrombosis in arteries: A) Stroke Definition: it is the rapid decline of brain function due to decrease of blood supply to the brain. Causes: this can be due to ischemia, thrombus, embolus or hemorrhage. In thrombotic stroke, a thrombus usually forms around atherosclerotic plaques. B) Myocardial infarction (MI) or heart attack Definition and causes: is caused by complete ischemia, often due to the obstruction of a coronary artery by a thrombus. This restriction gives an insufficient supply of oxygen to the heart muscle which then results in tissue death (infarction). 3- Thrombosis in the heart: Types and causes: A) Over the surface of the valves (vegetations) in endocarditis. B) Mural thrombus which occurs opposite myocardial infarction. C) Ball thrombus is formed inside the dilated left atrium in severe mitral stenosis.  Embolism An embolism is the lodging of an embolus (foreign material), inside a blood vessel. Types of emboli  Types of emboli 1- Detached part of a thrombus (thrombo-embolism): Non-infected emboli lead to infarction, while infected ones lead to pyemia. 2- Tumor emboli: produce secondary deposits in distant organs known as metastasis. 3- Parasitic emboli: spread of bilharzial ova leading to bilharzial granulation tissue and fibrosis in the liver or lungs. The entameba histolytica leads to amoebic liver abscess.  Types of emboli 4- Air emboli: This occurs in cut wounds in the neck or during brain surgery. Trauma to the lung and in severe diving. Venous air embolism leads to pulmonary embolism and infarction. Arterial air embolism is more dangerous and pass directly to coronary or brain circulation leads to myocardial infarction or stroke. 5- Fat emboli: In fracture bone, trauma to the soft tissue, burn and severe fatty liver, fat may enter into cut veins, leading to pulmonary embolism and infarction. 6- Atheromatous emboli: fragments from atheromatous plaque in the aorta leading to renal infarction and renal failure. Infarction and gangrene in lower extremities may also happen (purple toe syndrome). 7- Amniotic fluid emboli: an amniotic fluid embolism is a rare obstetric emergency in which amniotic fluid, fetal cells, hair, or other debris enters the mother's blood stream via the placental blood and triggers an allergic-like reaction which leads to respiratory failure and cardiovascular shock. Risk factors for embolism: 1- Thrombus in any part of the body. 2- Atrial fibrillation, mitral stenosis, myocardial infarction and stroke. 3- Atherosclerosis, diabetes and hypertension. 4- Aneurysm. 5- Prosthetic valves. Edema  EDEMA Definition: It is abnormal accumulation of fluids in the interstitium under the skin and serous sacs of the body. Causes of edema: 1. Increase in the permeability of the capillaries: inflammation and allergy. 2. Increase in the venous pressure: thrombus, heart failure and liver cirrhosis. 3. Decrease osmotic pressure of the plasma: protein loss in renal diseases, liver cirrhosis, malnutrition and pregnancy disorders as preeclampsia. 4. Lymphatic obstruction: inflammation, neoplasia, postsurgical and post irradiation. 5. Sodium retention: excessive salt intake with renal insufficiency, increase activity of renin angiotensin system and increase secretion of adrenal hormones. Edema Types of edema: 1- Local edema: A. Inflammation B. Venous congestion or obstruction C. Lymphatic obstruction D. Allergic edema (angionedema) 2- Generalized edema A. Right side heart failure B. Renal cause: Nephritic and Nephrotic syndromes C. Hepatic cause: liver cirrhosis D. Nutritional cause: protein malnutrition Types and causes of edema  Pre-eclampsia (PE) Definition: is a disorder of pregnancy characterized by high blood pressure and often a large amount of protein in the urine. Clinical picture: The disorder usually occurs in the third trimester of pregnancy. In severe disease there may be red blood cell breakdown, a low blood platelet count, impaired liver function, kidney dysfunction, edema, shortness of breath due to fluid in the lungs, or visual disturbances. If left untreated, it may result in seizures at which point it is known as eclampsia. Risk factors: obesity, prior hypertension, older age, and diabetes mellitus. It is also more frequent in a woman's first pregnancy and if she is carrying twins. Pathogenesis: The underlying mechanism involves abnormal formation of blood vessels in the placenta. Abnormal vascular development of the placenta leads to poor placental perfusion and poor trophoblastic invasion. It is thought that this results in oxidative stress, hypoxia, and the release of anti-angiogenic proteins and inflammatory mediators that promote endothelial dysfunction, hypertension, inflammation, and other possible reactions. Angioedema Angioedema: Definition: it is self-limited, asymmetric, localized non-pitting edema. Sites: periorbital, lips, tongue, extremity and bowel wall. Laryngeal edema is the main cause of death. Causes: 1- Idiopathic. 2- Allergic or IgE mediated angioedema. Type I hypersensitivity reaction commonly from food or drugs. 3- Hereditary angioedema. It is due to C1 esterase inhibitor deficiency. It is associated with trauma, anxiety, menstruation, exercise and alcohol. 4- ACE inhibitor angioedema. It occurs in patients taking ACE inhibitors due to elevated levels of bradykinin.  Differences between transudate and exudate they are fluids that escape from inside to outside blood vessels Transudate: due to increase Exudates: due to increase hydrostatic pressure vascular permeability Causes: Heart failure and liver Causes: inflammation and cirrhosis cancer 1- protein content Less than 1% More than 3% 2- Aspect Does not clot May clot due to presence of fibrinogen. 3- Specific gravity Less than 1015 More than 1015 4- Cells Few or absent Present in large numbers and their type depends on the type of inflammation. Gangrene Gangrene Definition: it is necrosis of tissue due to insufficient blood supply with color change. Gangrene usually starts by tissue injury and infection. Atherosclerosis, diabetes and smoking are common risk factors. Types of gangrene: 1. Dry gangrene. 2. Moist gangrene. 3. Gas gangrene. Gangrene Point of comparison Dry Moist Mode of onset Gradual Sudden Site of gangrene Limbs Limbs and internal organs Site of occlusion Artery Artery and veins Cause of necrosis Tissue anoxia Tissue anoxia or toxins Tissue fluids Decreased Increased Size of affected part Shrunken Swollen Line of demarcation Well formed Poorly formed Toxemia Mild Severe Course Slow end in self- Rapid and fatal separation Gangrene 1- Dry gangrene: It usually occurs in lower limb especially big toe as it is far from the heart. Causes: Necrosis due to cut of blood supply in: a. Atherosclerosis. b. Embolism. c. Spasmodic contraction of arteries: Raynaud's disease. Pathogenesis: 1- The affected limb is cold, pale, with loss of sensation. 2- The gangrene starts in the big toe and gradually ascends up the limb until there is an adequate blood supply. 3- The affected part becomes dry, shrunken and mummified. 4- Color changes appear in the form of red, green, and then black. 5- Putrefaction is absent and spread of gangrene is slow due to lack of fluids. The toxemia is minimal. 6- The living tissue just near the gangrenous part, become irritated forming thin line of granulation tissue called line of demarcation. Later on it is transformed into fibrous part and is called line of separation. If the gangrenous tissue is not removed surgically, the process may end with auto-amputation.  Gangrene Gangrene Gall bladder Gangrene big toe 2- Moist or wet gangrene: It involves death of tissues with severe infection and putrefaction. In wet gangrene, the tissue is infected by Clostridium perfringens which cause tissue to swell and emit bad odour. I. Moist gangrene of the limbs: gangrene of limbs may be of the moist type in the following conditions: a. Diabetic patients: as sugar favors infection and edema b. In old persons: if there is edema of lower limbs due to any cause. c. Following severe crushing injury of the limb, a thrombus will occur in both arteries and veins. II. Internal organs: Intestines, lungs and appendix. III. Moist gangrene of the skin of the back known as bed sores. Pathogenesis: 1. The affected part is swollen, edematous and may be ulcerated. 2. Color changes are very rapid. 3. Putrefaction is maximal with very bad odor and marked acute toxemia. 4. The line of demarcation will not appear because the process of gangrene is rapid. Gangrene Bed sores Bed sores (pressure ulcer) Definition: Damage, ulcer and moist gangrene of skin of the back due to prolonged recumbancy (bedridden). Causes: 1- Paralysis and fractures in old age. 2- Postoperative periods. 3- Atherosclerosis and diabetes. Sites: It occurs over the sacrum, buttocks and upper back. Pathogenesis: the disease is caused by ischemia due to compression of skin blood vessels specially if complicated by atherosclerosis and diabetes. Pressure of the skin opposite the bony prominences leads cut of blood supply in the arteries of skin. Deep ulcers occur followed by anaerobic infection with necrosis of tissue and severe fatal toxemia and septic shock. DIC Disseminated intravascular coagulation (DIC) Definition: DIC is a thrombo-hemorrhagic disorder that occurs as a secondary complication in a variety of diseases. Major disorders associated with DIC. 1. Obstetric complications. - Retained dead fetus. - Septic abortion and amniotic fluid embolism. 2. Infections especially gram negative sepsis. 3. Neoplasms: - Mucin secreting adenocarcinoma. - Acute leukemia. 4. Massive tissue injury as severe trauma and burns. 5. Others as snake bites, shock, heat stroke, and liver diseases. Pathogenesis of DIC: DIC begins with sudden onset of wide spread fibrin thrombi in the micro circulation and cause diffuse circulatory insufficiency. There is rapid associated consumption of platelets and coagulation proteins. At the same time fibrinolytic enzymes are activated and as a result an initially thrombotic disorder can evolve into sever bleeding disorder.