Cell Death and Perfusion Disorders 3 Flashcards
Define congestion
Accumulation of blood in a vascular bed due to reduced or obstructed outflow.
Define hypostatic congestion
Gravitational pooling of blood in a dead animal.
What kind of heart failure leads to chronic passive congestion of the liver?
Right sided heart failure.
Essentially, when the right side of the heart is not moving fluid, the liver is the first capillary bed where blood backs up.
How can right heart failure cause liver issues?
Elevated central venous pressure - venous back up - congestion in zone 3 - progresses to zone 3 ischemic necrosis. cells in zone 1, around the portal tract, are spared but necrosis occurs in zone 3.
What is nutmeg liver
Chronic passive congestion of the liver from right heart failure causes the liver to look like a nutmeg.
Where do you see lack of blood flow in left sided heart failure?
In the lungs
What kind of fluid can ooze from the liver with chronic passive congestion?
Proteinaceous fluid can ooze from the surface due to elevated central venous pressure. Fibrin polymerizes on the surface. Ascites may accumulate in the peritoneal cavity.
What do lungs look like when the — side of the heart is in failure?
Chronically congested lungs due to left heart disease (not moving blood forward) cause heart failure lung, which isn’t very common in vet med.
Colour rusty due to hemosiderin in alveolar macrophages. Red cells leak to alveoli, macrophages.
What do heart failure cells look like (LS)?
Alveolar macrophages containing phagocytosed red blood cells, which have leaked from pulmonary capillaries congested by left heart failure. Hemosiderin (rusty colour) in such cells acts as a microscopic marker of congestion. Also get edema in alveoli which is bad for gas exchange.
What are the thing that contribute to the significance/sequelae of congestion?
- signals circulatory problem
- predisposes to thrombosis (blood not flowing properly promotes clotting)
- leads to edema
- dependent on degree and duration of vascular obstruction, oxygen depletion may lead to hypoxic necrosis/infarction of cells/tissue (how large area affected, how long, how profound hypoxia)
What can cause hyperaemia of sclera?
Dilated capillaries on the scleral surface of conjunctivitis. Mediators of acute inflammation promote vasodilation and increased blood flow (and exudation of inflammatory cells to where needed). Try to increase blood flow to tissue for inflammation.
What are the cells that often make up dirty brown coagulated material?
-neutrophils
-dead cells
-debris
-fibrin leaked from open dilated cells
Dirty yellow exudate leaks from damaged vessels and covers inflamed, eroded mucosal surface
How does the signalling of adaptive circulatory phenomenon have a role in hyperaemia?
- increased oxygen demand
- heat dissipation (increased cutaneous vascular flow)
- Inflammation (most important)
Define hyperemia
The opposite of coagulation. The active physiological increase in flow of bright red oxygenated blood into a tissue. Results from arteriolar dilation
Define hemorrhage
Extravasation of blood. Leakage of erythrocytes and plasma into the interstitial space. RBCs outside the vascular system treated as a foreign body.
How can hemorrhage be recognized grossly?
- free blood in space or cavity
- bright red to deep red-blue colour in tissue in a distribution not conforming to vascular pattern, often accompanies congestion and may be difficult to differentiate
How can hemorrhage be recognized microscopically?
RBCs outside vessels, free in tissue
What is the differenced between petechiae and ecchymoses?
Both are types of hemorrhage. Petechiae are smaller, often pinpoint.
What diseases are petechiae and ecchymoses patterns often seen with?
Bacterial septicemia, systemic viral infection, thrombocytopenia (not enough platelets), vasculitis (inflammation of blood vessels), DIC
What does focal hemorrhage imply?
Local vascular damage sufficient to permit red cells to leak.
What lesion is often present in dogs with canine parvovirus infection?
Petechial to ecchymotic and/or paintbrush hemorrhages on the serosal surface of a segment of canine small intestine.
What property of muscle gives the ability of paintbrush hemorrhage to form?
The fibrous nature. Vascular damage and consumption coagulopathy leads to hemorrhage.
Define hemopericardium
Leakage of blood into pericardial sac.
What can hemopericardium result in?
Cardiac tamponade
Define cardiac tamponade
A modest volume of blood in the pericardial sac physically preventing the heart from pumping blood.
What does rupture or laceration of a cardiac vessel or the myocardium produce?
A compressive blood clot or hematoma within the pericardial sac. A common cause is a tumour on the right auricle called hemangiosarcoma (prevents refill in diastole).
What can hemoperitoneum be caused by?
Laceration of the liver, spleen, kidney or a splanchnic blood vessel. Can also be from ruptured hepatic/splenic hemangiosarcomas or hepatocellular carcinomas, anticoagulant rodenticides.
What does the significance of hemorrhage depend on?
- site or location (cardiac tamponade, subdural hematoma which is a small hemorrhage that can cause pressure on brain, hemoabdomen)
- rate and volume of blood loss (shock vs blood loss anemia)
What is the difference between shock and blood loss anemia?
Shock is a loss of large volumes of blood, blood loss anemia is a loss of blood over time.
What is the diagnostic significance of hemorrhage?
- trauma
- vessel defect/rupture (eg aneurysm)
- vascuopathy and/or clotting defect (clotting factor deficiency/thrombocytopenia, sepsis-microvascular damage), endotoxemia
Define endotoxemia
Microvascular damage/clotting defect due to consumption coagulopathy.
What does melena mean?
The passage of black tarry stools. Means that blood is coming from high up in the digestive tract and being digested.
What is the fate of hemorrhage in the body?
Whether diffuse or focal/localized, hemorrhages are reabsorbed by the body. The red cells are broken down and catabolized (pigments by macrophages.
What is a hematoma converted to?
Connective tissue through the process of wound repair (organized).
What do pigments and degree of organization assist?
Aging
What are the three causes of red part in tissue?
- hemorrhage
- hyperemia
- congestion
What is the name of the thing that acts along the length of capillary to maintain capillary pressure?
Starling forces
Define edema
Exceeded ability of lymphatic system to drain fluid.
What are the starling forces?
-hydrostatic pressure forces fluid out of the vessel
-Interstitial fluid colloid osmotic pressure draws fluid out
balancing these are:
-Interstitial hydrostatic pressure which may be quite low in elastic tissues
-plasma colloid osmotic pressure
What are the four causes of edema?
- increased hydrostatic pressure
- Increased vascular permeability
- decreased plasma osmotic/oncotic pressure
- lymphatic obstruction
Give an example of increased hydrostatic pressure causing edema
Obstruction of venous outflow. Heart failure (lack of forward flow) - increased central venous pressure - generalized edema (subcutis, ascites, hydrothorax) Torniquet compressing a vein - increased pressure in local vascular bed - edema in tissue that is normally drained by that vein
Give an example of increased vascular permeability causing edema
Inflammation or vessel injury.
This is usually localized or else the animal is dead.
Inflammatory mediators - leaky endothelium - edema in the inflamed site
Give an example of decreased plasma osmotic pressure causing Edema
Hypoproteinemia (low protein in blood, albumin normally holds fluid in vascular system)
Hypoproteinemia - decreased plasma oncotic pressure - generalized edema
Give an example of how lymphatic obstruction causes edema
Eg tumour in local lymph node
Metastasis of tumours into lymph node lead to obstruction of drainage.
Tumour in lymph node - decreases lymph drainage - edema in the local tissue that drains to the node.
What kind of tissues does edema tend to accumulate in?
Loose tissues, subcutis.
An example is in the loose areolar connective tissue between muscle and deep dermis.
What can cause foam on a lung?
Edema with surfactant due to pulmonary congestion. Froth escaped from airways.
Presence of what two cells indicates inflammation?
Neutrophils and macrophages
Define hydrothorax
Fluid in the thoracic cavity
Define ascites. What is it typically from?
Fluid in the abdominal cavity. Typically due to portal hypertension or hypoproteinemia.
What are the outcomes of edema?
- often reversible
- vary with location and duration
- If cause is reversible, edema and fluid in body cavities is reversible in early stages
- tissue impacts
- chronic edema can cause fibroplasia or fibrosis
In the outcomes of edema, what are the possible tissue impacts?
- space occupying compression (eg external - lungs in hydrothorax; internal - brain in cerebral edema) can fill space and interfere with function
- Impaired function (pulmonary edema)
What is fibroplasia/fibrosis?
Scar tissue - chronic process, takes days or weeks to form. Chronic edema can lead to scarring.
Define thrombosis
Inappropriate coagulation of blood in the lumen of a vessel, usually attaches to wall.
Define embolus
A mass (ie detached fragment of a thrombus, tumour cells, fat, hair, parasite larva etc) that travels in the bloodstream and eventually lodges in a vessel.
What can large vessel thrombosis cause?
Occlusion of a single vessel. In micro vessel, can occlude capillary beds
What is Virchow’s triad?
The three predispositions to thrombosis include endothelial injury (most important, significant if widespread), hyper coagulability (excessive clotting can lead to thrombosis), abnormal blood flow (stasis, turbulence)
What are some common causes of severe thrombosis?
Mainly endothelial disruption, all life threatening
- severe trauma (exposed collagen, release of tissue factor activates clotting)
- sepsis/septicemia (increased endothelial tissue factor, endothelial damage)
- vascular injury (exposes sub endothelial collagen)
- shock (ischemia-induced necrotic tissue activates clotting)
- protein losing nepropathy/enteropathy (loss of anticoagulant proteins like antithrombin iii)
- cancer (tumour cells in vessels adhering to/damaging endothelium
- cushing’s disease in dogs (hyperadrenocorticism)
What are the fates of a thrombus?
- propagation towards heart
- resolution (wound healing)
- embolization to lungs, organized and incorporated into wall (bigger clots)
- organized and recanalized (paths for blood flow open, thrombus gets more organized)
What are the consequences and significance of large vessel thrombi?
- occlusion of vessel (lack of O2); ischemic necrosis/infaraction
- thromboembolism (distant infarction; sepsis if thrombus is infected)
- vasculitis, degeneration of vessel wall at site of thrombus (inflammation of BV wall, have endothelial damage)
What does the significance of large vessel thrombi depend on?
- rapidity of development
- completeness of occlusion
- availability of collateral circulation
- metabolic requirements of affected tissue field
Why is thrombosis of the pulmonary artery fatal?
No forward flow of blood leads to shock. Lack of venous return, pooling of blood.
Are saddle thrombi in horses deadly?
Not as much as in cats as they develop slowly in horses.
True or false: Masses of malignant neoplastic cells may metastasize by embolism in venous and arterial blood,
True. The pattern of blood flow to filtering organ matters when considering metastatic tumour origin.
What is DIC?
Disseminated intravascular coagulation, death is coming.
- severe systemic activation of the coagulation system leads to systemic microvascular thrombosis and depletion of platelets and clotting factors
- concurrent systemic thrombosis and hemorrhage
- cause is either widespread injury to endothelium or widespread release of tissue factor or other thrombogenic substances resulting in diffuse (systemic) activation of the coagulation cascade
- major features include thrombosis in microcirculation, tissue ischemia, consumption of platelets and clotting factors, fibrinolysis, concurrent bleeding and coagulation
