patho sheet # 3 of Dr Fasial -valeria Manfal6i

View previous topic View next topic Go down

patho sheet # 3 of Dr Fasial -valeria Manfal6i

Post by Shadi Jarrar on 6/12/2010, 2:09 pm

بسم الله الرحمن الرحيم

_____________________________________
http://www.freefileconvert.com/converted/4cfc7c2e7d2e9/Aneurysm.doc
_____________________________________


Aneurysm: weakening in the wall of aorta so that normal blood pressure will cause localized dilation (balloon out); usually it has several complications, like rupturing of the walls.
Most imp./famous/common:
1- Lower abdominal aortic aneurysm.
2- Base of the brain, where it is berry in shape leading to its name Berry aneurysm, also it is famous to be congenital (although some ppl deny this), and its usual sight is at or about the circle of Willis.
• An example on hemorrhage that occurs due to erosion of blood vessels is Tb and cancer.
• Capillary hemorrhage has many causes, but one of the most imp. Factors is deficiency in some materials such as Vitamin C (in gum or in any other place), where this can lead to bleeding. Another imp. Factor is deficiency of 1 or more of the coagulation factors; in addition; capillary hemorrhage might result from blunt trauma (e.g. pulmonary hypertension, chronic passive congestion of the lung).
Sizes of injury:
o If the hemorrhage Diameter about 1-2 mm then it is called Petechiae(puncted /pin point) example: classical peptic ulcer and varicose vein( varicosity of the wsophegeal plexus can cause rupture)
o If it is up to several mm in diameter then we call it purpura
o hemorrhage
o if larger (about 1-2 cm) (arterial hemo. ) then called Ecchymosis and this type may cause hematoma (if it is form subcutaneous bleeding it might undergo color change)
1st color change is bluish (due to the collection of unoxygenated blood)
2nd yellowish green color (as RBC’s are eaten up by macrophages, and digested enzymatically into bilirubin
3rd golden brown (due to further digestion and the formation of hemosidrin)
4th color fades away..: D

• the classical example of this is the black eye formed when hitted (periorbital hematoma )
• Sometimes forensic medicine uses these color changes to determine the exact time of the hit.
• Hematoma depends on several factors among which:
Size
Site
Time needed for formation (if we have a large amount in short period this may lead to hypotension and even death.)
E.g. a big hematoma in the abdomen might me just accompanied with pain, while a small hematoma in the brain might cause DEATH.

The hemorrhage takes the name by the site where it takes place like:
• Hemorrhage in joints called Hemarthrosis
• Hemorrhage in pericardium called Hematopericardium/ hemopericardium.


Thrombosis: is a mass within the cardiovascular system formed during life
from blood constituents.
Sometimes In forensic medicine they have to prove if the cause of death is thrombosis or postmortem clot.

Factors which might promote thrombosis:
1-Relates to the endothelium:
o Endothelium is a single cell layer which invests the cardiovascular system from inside, but in the heart it is called endocardium .it can be injured(trauma) or there can be sort of endothelial dysfunction( function of the endothelium is disturbed not due mechanical trauma but due to many other injurious agents such as increase in temperature, chemical substances like Oxygen in ischemia….etc, as a conclusion we can say that sometimes it is not mechanically injured but might undergo dysfunction.)
o Thrombosis due to endothelial injury is more common on the arterial side of the cardiovascular system and the heart rather than the venous side.
o An example: myocardial infarction
Myocardium is supplied from the coronary arteries/coronary arterial tree( the inner most fibers of the myocardium, close to the lumen( endothelium) might take at large it’s blood supply from the coronary arteries, but also can be supplied directly from the lumen, therefore; endothelial cells are least affected by myocardial infarction).
2-Patterns of the flow of the blood:
• Blood travels within the blood vessels in a laminar flow( in a way where the stream is more rapid in the center than in the periphery, in addition, platelets travel in the mid current without approaching the periphery( with some exceptions) while in the periphery the more fluid part of the bold travels ( plasma, formed elements…etc.) i.e. as if platelets try to escape the touch with the endothelial cells in order not to activate the endothelial cells or platelet themselves ( where they adhere and cause thrombosis)
• If turbulence/eddy current occur(electrical charges might play some role in pilling platelets from the mid current) then we are approximating the elements of blood abnormally get in touch with the walls of blood vessels so promoting thrombosis.


3-Hypercoagulability states:
There are certain conditions some of which are primary (e.g. gene mutation leading to missing or impaired or inactivated anticoagulant) or secondary (e.g. aging: as one gets older the chance of promoting hypercoagulation increases.)

Contraction is most active in an area which is 1 inch from the apex( esp. left ventricle, which is the thickest plus the most vigorously active), once this area becomes ischemic MI (myocardium is no longer synchronous with the healthy myocardium)

Cardiac valves might undergo inflammation due to several causes. One of the most important conditions is infective endocarditis (infective endocarditis used to be called acute bacterial or sub-acute bacterial but not anymore because they used to think that the infection is done by bacteria only but some of them are due to fungi or viruses.)
• If the valve is damaged it might cause reaction to 1 or more of heart chambers, it can cause stenosis/murmurs/incompetence, this might be a great burden on the heart so that it might cause death.
• The valve will be replaced by Prosthesis made of different materials:
1. Bio-valve: valve from a dead person or from a pig (swine valve) or bovine.
2. Mechanical: carbon, metal.
Also they can come in different shapes but the end function is similar.
• All prosthesis especially metal ones might induce coagulation because platelets and endothelium are traumatized so these might induce thrombosis.
Hypertension it is a mechanical injury where blood hit against the
endothelium forcefully causing injury promoting thrombosis.

Toxicity: any toxicities reaching the endothelium might promote thrombosis.

Stasis:
Varicose vein of the LL, ( irregular thickening and thinning lead to some irregularity in the dimensions of the superficial veins, then this irregular wall will permit stasis(stagnation of the blood) therefore; some of the platelets will settle at the endothelium, esp. if oxygenation is low, it will endanger both the endothelium and the subendothelial Connective tissue, so platelets will be activated leading to thrombosis.
Q: why females are more affected???
Ans: Bcz females have a greater tendency to be more in weight plus the muscle support in males is more (milking of veins is more).

Rheumatic heart disease; it is due to inflammation.
1- It affects all the layers of the heart but 1 layer more than the other.
2- It targets the valves more than any other part in the heart (esp. with chronicity or repetitive attacks).
3- Mitral valve is most frequently affected
4- It will promote thrombosis, why??
Because cusps of the valve are smooth and opposing 1 another very smoothly, but sometimes due to infection, trauma, etc… irregularities form. In Rheumatic fever, deposition of material and irregularities (these are thrombi in small amounts) causing wart like elevation along the line of closure of the mitral valve (vegetation).
Inflammation ulceration/erosion healing by fibrosis deposition of platelets, injured endothelium, fibrin and fibrous tissue irregular valves.
So it becomes narrower and doesn’t open very well, where blood won’t be able to pass from the atrium (during ventricular contraction, mitral valve doesn’t close good, where some blood will pass back into the left atrium)

• Atria fibrillation: electrical waves conduction is irregular/ NO synchronous and homogenous contractions, this will cause change in the pattern of blood flow for several reasons (stasis, injury)
• Atherosclerosis ( arterial disease)
Thickening of the intema
Increase in the thickness of the wall
Bcmz weaker
These hinder the flow of blood as if there is relative stasis proximal to it.
Might undergo ulceration 1- irregularity of blood flow 2- endothelium is being injured by endogenous/exogenous substances
3-platelets might settle on it.
Venous:
Blood flow in veins is slower esp. in LL , pregnant uterus and tumor( impeding venous return)

• Thrombi give rise to embolization
• Varicose veins are superficial ( tributaries of saphenous vein don’t emboli that much)
• Deep vein thrombosis is dangerous
• During long flights people should move their legs in order to milk up blood from veins( Immobilization is very dangerous in terms of thrombosis)



Best of wishes,
Valeria Manfalouti
avatar
Shadi Jarrar
مشرف عام

عدد المساهمات : 997
النشاط : 12
تاريخ التسجيل : 2009-08-28
العمر : 26
الموقع : Amman-Jordan

http://jude.my-rpg.com

Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum