Saturday, November 14, 2009
Chronic venous congestion (CVC)
Alhamdulillah..praise to Allah..
it's been about a month of haematology block being conducted..
it's quite tough compare to the last block..and my blog also recently been outdated since the schedule are too compact along the weeks..
ok..i take this time updating my blog by making some sharing of knowledges..perhaps it might useful to all of my frens..
Chronic venous congestion (CVC)..
I thinks all of us had revised the hand-out lecture of hypermia..let just focus on the chronic venous congestion/chronic systemic congestion based on the hand-out..
Caused by : chronic right side heart failure..
due to several factors:
(ii)left heart failure
Def : a valvular heart disease characterized by narrowing of the mitral valve of the heart..
actually..mitral stenosis is also a cause for the left side heart failure..so,it's the best to decribe this disease in upper-hand in it's mechanism of causing the right side heart failure rather than the left side heart failure(such as in the hand-out)..
in mitral stenosis..the mitral valve are narrowed causing some blockage of transferring the blood from the left atrium to the left ventricle to be pump out all over the body..
lets imagine..of how if a blockage at atrioventricular junction of the left side..
sequently..in continuation of blood transfer from the lungs through the pulmonary veins,an increase of pressure on the left atrium will occur since the blood slowly pass through to the left ventricle..
this pressure causing a backflow of blood into the pulmonary vein which supposely transfer
the oxygenated blood from the lungs to the heart..
and by now it become backwards..the blood are pushed from the left atrium to the lungs through the pulmonary veins instead!!..causing increase hydrostatic pressure of the pulmonary vasculature in the lungs..
now we focus on:
CVC of the lungs
the increase of hydrostatic pressure of the pulmonary veins is transmitted throughout the microcirculation(capillaries) in the lungs..
the pressure increases causing engorgement of the blood vessels consequently lead to rupture of some capillarries..this condition give an oppertunity of RBC escaping into the tissue of the alveoli (haemorrhage)..this escaped RBC are ruptured when they enter the tissue and haemoglobin will be released..
the released Hb will then be engulf by macrophages and being degraded into haemosiderrin..which can being seing as brown pigments from the microscope..this known as the 'hemosiderin-laden macrophages' OR the 'heart failure cells'..
Prof just once told that..once the laden is formed or seen..it's also indicate that the right side heart failure have occured by the same time..the more increasing the number of the laden,the chronic of the right side of the heart is being..that's why it is called the 'heart failure cells'..
How come the right side could be affected?
it is the same theory as above..when the microcirculation of the lungs is affected..there is also increase of hydrostatic pressure at the pulmonary artery which suppose to transfer deoxygenated blood from the heart to the lungs..
i.e,there is backflow of pressure from the lungs to the right ventricle through the pulmonary artery...
so..the right side of the heart are now affected..the systole and diasystole are now being disturbed..so the heart are now cannot pump the blood properly..
so..it is said that the right side heart failure occur secondary to the mitral stenosis which ends up in the systemic venous congestion...i.e:the other organs will also be affected consequently...
that's is how the mitral stenosis causing the right side heart failure.
2)Left side heart failure
the pathway is almost the same as the mitral stenosis in causing right side heart failure..
but in factors causing left-side heart failure,there are several factors rather than the mitral stenosis..such as aortic disease or dysfunction of left ventricle..etc..
in pulmonary disease..there is increase of hydrostatic pressure of pulmonary circulation might cause by embolism or infection or etc..which then lead to the right side heart failure..
actually it is a late sequale of inflammation of the pericardium surrounding the heart..i.e..there is fibrosis of the pericardium consequently after the inflammation due to severe infections..
the fibrosis form around the pericardium make a shell preventing the heart from expanding when blood enters through it..the regulation of the systole and diasytole are disturbed..and heart failure of both side occured..leading to congestion of pulmonary circulation..
Some questions i've been encounter with
What are cardiac cirrhosis?
i've had confirm with the prof..they said it is liver cirrhosis secondary to the heart failure..
what does it means?..
in liver cirrhosis,they are multiple of causes such as viral infections,alcoholism and etc..but in this case,the liver cirrhosis is due to the systemic congestion of the heart leading to occurance of centrilobular necrosis and subsequently central fibrosis of the liver..thus,it is more commonly called cardiac cirrhosis..
Why are central hepatocytes are more affected in undergoes cell injury rather than peripheral hepatocytes?
if we flashback on our mind..the central hepatocytes are nearer to the portal vein rather than the peripheral hepatocytes..we know that,vein contain deoxgenated blood..thus,the central hepatocytes are more affected to hypoxia and will undergoes cell injury rather than peripheral hepatocytes which are nearer to the arterioles and can still receive oxygenation from the blood..
But in chronic stage..the central hepatocytes will undergoes necrosis..and the some of th peripheral will also undergoes cell injury(fatty changes)
why are in acute stage,the alvelar septa of lungs are oedomatous but in chronic stage,it is fibrotic?
when in chronic stage,the septa will undergoes healing by fibrosis since the causes are severe and didn't be treated..causing the fibrosis of the septa..and thickening of it..
ok.. i think it is enough from here..
actually,what i'm explaining is based on my level as a 2nd year student..there is a wide broad of pathophysiology of heart failure due to congestion..
there are other colleagues whom are better on explaining part of this..so,any mistakes of mine..i'm sorry and i'm opened for discussion..
you may refer any international books or websites for more understanding..
i'll end up my writting with this hadith(in malay) to consult it within ourself:
Rasullah S.A.W bersabda:
"ada dua macam nikmat yang sering dilalaikan oleh bnyk manusia iaitu nikmat kesihatan dan nikmat waktu"