2 Cardiovascular disease Most important cause of morbidity and mortality in developed nationsIn US, 81 million affected in 2005, causing 35 to 40% of deathsComponents of cardiovascular system includeHeartVesselsBloodWater, salts, proteins, clotting factors, cells
3 Blood Hemodynamics Edema Hyperemia Congestion Shock Water build-up in interstitial spaces and cavitiesHydrodynamic transudate is dilute, protein-poorInflammatory exudate is concentrated, protein richHyperemiaAcute, actively increased blood flow—arteriole dilation, increased heart rateTissues look red (erythema)CongestionChronic, passively reduced outflow—venule dilationTissues look pale or blue (cyanosis)ShockCirculatory failure
4 Fluids—waterThis unit addresses factors affecting the distribution between intravascular and interstitial spaces
5 Factors affecting intravascular and interstitial water movement Concentration of solutesAlbumin and other proteins (huge difference)Sodium and other ions (small difference)Hydrostatic pressureHigher on arteriolar sideLower on venular sideLowest in interstitiumBlood volume decreased b.p.Water intake/deprivationWater loss from skin or gutPerspiration, vomiting, diarrheaBlood loss; acute hemorrhage
6 Fluid transitFIGURE 4-1 Factors influencing fluid transit across capillary walls. Capillary hydrostatic and osmotic forces are normally balanced so that there is no net loss or gain of fluid across the capillary bed. However, increased hydrostatic pressure or diminished plasma osmotic pressure will cause extravascular fluid to accumulate. Tissue lymphatics remove much of the excess volume, eventually returning it to the circulation via the thoracic duct; however, if the capacity for lymphatic drainage is exceeded, tissue edema results
7 EdemaLocalized or generalized accumulation of fluid in interstitial spacesAnasarca: severe, generalized edemaana = throughout, sark = fleshMost commonly used to describe fetal or neonatal whole-body, subcutaneous swellingEffusions into body cavitiesHydrothorax: within thorax, around lungs; also pleural effusionHydropericardium: Fluid in the pericardial sacHydroperitoneum or ascites: Fluid in the peritoneal cavityExtravasate: (v.) to move out of the vasculature
8 Responses to edema Skin: swells according to elasticity dependent edema: distribution affected by gravity (ankles, sacrum)dependent = hanging down in this contextBrain: compresses without room to swellLung: alveoli fill preventing gas exchange
9 Appearance of edemaSwollen tissues (not cells—fluid is outside the cells)Heavy tissuesWet tissuesWidening of fascial planes or interlobular septaFilled cavities
10 Causes of edema Increased hydrostatic pressure Focal impairment—deep vein thrombosisGeneralized impairment—right heart failureDecreased plasma osmotic pressureHypoproteinemiaDecreased protein synthesis—serum albuminIncreased protein loss to nephrotic syndromeSodium (and water) retentionIncreased capillary permeabilityinflammation or injury (burns)Lymphatic obstructionFilariasis, breast carcinoma
11 Appearance and causes of hyperemia Increased flow of blood into tissueLocal process of arteriole dilation greater than venule dilationAppearance of blood flow is REDNormal physiological examples:ExerciseBlushingErectionInflammatory response (rubor)Small contribution to edema
13 FIGURE 4-2 Pathways leading to systemic edema from primary heart failure, primary renal failure, or reduced plasma osmotic pressure (e.g., from malnutrition, diminished hepatic synthesis, or protein loss from nephrotic syndrome).
14 Congestive heart failure Right side failure—volume backs up behind pulmonary circulationGeneralized edemaPortal edema—nutmeg liverLeft side failure—volume backs up behind systemic circulationPulmonary edema and pleural effusionDistension of alveolar capillaries leading to capillary rupture and red cells in alveoliIntra-alveolar macrophages phagocytose red cells and accumulate hemosiderinFibrosis of the interstitium with hemosiderin depositionSerous or serosanguinous effusions surrounding lungs
15 Congestive heart failure Reduced cardiac outputRenal hypoperfusionActivation of renin-angiotensin-aldosterone axisEarly response is beneficialsodium and water retention increased vascular toneelevated antidiuretic hormone (ADH) improved cardiac outputrestored renal perfusionOngoing response increases edemaVolume of blood exceeds volume of vasculatureFluids build up in tissues
18 Trivial and life-threatening edema This example of a fluid collection, a friction blister of the skin, is an almost trivial example of edema.This example of edema with inflammation is not trivial at all: there is marked laryngeal edema such that the airway is narrowed. This is life-threatening. Thus, fluid collections can be serious depending upon their location
22 Ascites due to portal congestion American Gastroenterological Association, AGA Teaching Project, 1975 UI Medical Library call # WI, 720, P8423, 1975Ascites with "caput madusae" (medusa head), also known as "Cruveilhier-Baumgarten Syndrome". Cirrhosis and portal hypertension sometimes create anastomoses of portal drainage with the umbilical vein. Also note protrusion of the naval from abdominal pressure.
23 Nutmeg liverHere is an example of a "nutmeg" liver seen with chronic passive congestion of the liver. Note the dark red congested regions that represent accumulation of RBC's in centrilobular regions. Microscopically, the nutmeg pattern results from congestion around the central veins, as seen here. This is usually due to a "right sided" heart failure.
24 Hepatic congestionIf chronic hepatic passive congestion continues for a long time, a condition called "cardiac cirrhosis" may develop in which there is fibrosis bridging between central zonal regions, as shown below, so that the portal tracts appear to be in the center of the reorganized lobule. This process is best termed "cardiac sclerosis" because, unlike a true cirrhosis, there is minimal nodular regeneration.If the passive congestion is pronounced, then there can be centrilobular necrosis, because the oxygenation in zone 3 of the hepatic lobule is not great. The light brown pigment seen here in the necrotic hepatocytes around the central vein is lipochrome.
25 EffusionsExtravascular fluid collections can be classified as follows:Exudate: extravascular fluid collection that is rich in protein and/or cells. Fluid appears grossly cloudy.Transudate: extravascular fluid collection that is basically an ultrafiltrate of plasma with little protein and few or no cells. Fluid appears grossly clear.Effusions into body cavities can be further described as follows:Serous: a transudate with mainly edema fluid and few cells.Serosanguinous: an effusion with red blood cells.Fibrinous (serofibrinous): fibrin strands are derived from a protein-rich exudate.Purulent: numerous PMN's are present. Also called "empyema" in the pleural space.
26 Pleural effusions and edema This is a right pleural effusion (in a baby). Note the clear, pale yellow appearance of the fluid. This is a serous effusion.Here is an example of bilateral pleural effusions. Note that the fluid appears reddish, because there has been hemorrhage into the effusion. This is a serosanguinous effusion.
27 Fibrinous exudate Fibrinous exudate of pericardium