Hemodynamic Disorders(Disorders of blood flow)

Dr. Abdelaty Shawky Dr. Gehan MohamedDr. Abdelaty Shawky Dr. Gehan Mohamed

InfarctionInfarction

* Definition:Development of an area of coagulative necrosis (liquefactive in the brain) caused by acute cut of blood supply.

* Causes: 1. Thrombosis. 2. Embolism.

* Types of infarcts: 1. According to the color:a. Red infarcts (hemorrhagic): - Occur in vascular organs as the lung, liver and intestine. - The red color is due to hemorrhage in the substance of the infarct.

b. Pale infarcts: - Are more common and occur in firm and less vascular organs as the kidney, heart and spleen.

2. According to the consistency:a. Firm: in all organs infarction except the brain.b. Soft: in brain and spinal cord infarction.

3. According to presence of absence of the bacteria:a. Septic infarction: in intestine.b. Aseptic infarction:

Infarction of the kidney

Infarction of the spleen

Infarction of the lung

(hemorrhagic red infarction)

Infarction of the lung

(hemorrhagic infarction)

Intestinal infarction → Gangrene

* Fate of the infarct:

• Small infarct: Necrotic tissues are removed by macrophages,

granulation tissue fills the defect followed by fibrosis.

• Large infarct: Gets surrounded by a fibrous capsule and its

substance may show dystrophic calcification.

HAEMORRHAGEHAEMORRHAGE

* Definition:Escape of blood outside the blood vessels or cardiac chambers.

* Causes of haemorrhage:1. Trauma: involving the heart and blood vessels.2. Diseases of blood vessels: a) Hypertension. b) Varicose veins: as piles. c) Degeneration: as atheroma and aneurysm. d) Infection: as tuberculosis. e) Malignant cells invading blood vessels.3. Hemorrhagic blood diseases: as haemophilia,

leukemia and scurvy.

* Types of haemorrhage:

1. External haemorrhage.

2. Internal haemorrhage

3. Interstitial haemorrhage

1. External haemorrhage Escape of blood outside the body.

1. Epistaxis: Bleeding from the nose. 2. Hemoptysis: Coughing of blood. 3. Hematemesis: Vomiting of blood. 4. Melena: Presence of dark digested blood in stools. 5. Bleeding per rectum: passage of red blood with stool

6. Hematuria: Blood in urine.7. Menorrhagia: Excessive or prolonged

menstrual bleeding.8. Metrorrhagia: Irregular uterine bleeding

unrelated to menses9. Bleeding from skin

2. Internal haemorrhage Bleeding into body cavities.

1. Hemothorax: Hge into the pleural sac.

2. Hemopericardium: Hge. into pericardial sac.

3. Hemoperitoneum: Hge. into peritoneal sac.

4. Hematocele: Hge. into tunica vaginalis sac.

5. Hemoarthrosis: Hge. into a joint cavity.

3. Interstitial haemorrhage Bleeding into interstitial tissue spaces.

1. Petechial haemorrhage: escape of small amount of blood of capillary origin →

small spots of haemorrhage.

2. Ecchymosis: escape of moderate amount of blood → a bigger

patch of haemorrhage.

3. Hematoma: escape of large amount of blood causing a swelling.

- Interstitial haemorrhage is at first dark red (arterial blood) or bluish (venous blood).

- Then, hemoglobin breaks down into biliverdin and hemosiderin.

- BiIiverdin gives the area a green color but is soon absorbed in the blood.

- The hemosiderin left gives the area a brown color and is gradually removed by macrophages, so the color changes to yellow and gradually fades away.

* Effects of haemorrhage:● Small amount: No effect.

● Repeated small amounts (chronic hge): - Causes microcytic hypochromic anemia. - e.g. in piles and peptic ulcers.● Massive amount: hemorrhagic shock.

EdemaEdema

* Definition: - Pathological accumulation of excess fluids in the interstitial tissue spaces and serous sacs.

- Edema fluid may be either transudate, exudate or lymph.

Exudate TransudateOccurs in cases of inflammation. Caused by conditions other than

inflammation

High protein content (4-8 gm%).

Low protein content (below 3 gm%).

Specific gravity above 1018. Specific gravity below 1015.

Clots on standing (presence of fibrinogen)

Does not clot on standing. (no fibrinogen)

Contains inflammatory cells. No inflammatory cells.

* Causes of edema:1. Increased capillary hydrostatic pressure: occurs in cases of : - venous congestion (generalized or localized)

- sodium & water retention → ↑ blood volume

2. Decreased plasma colloid osmotic pressure: occurs in cases of hypoproteinemia (fall of total plasma proteins

below 2.5 gm% or fall of serum albumin below 1.5 gm%)

3. Increased capillary permeability: - Caused by toxins, hypoxia, & chemicals (e.g. histamine in acute

infl.).

- Escape of proteins into Interstitial fluid → ↓ plasma osmotic pressure & ↑ tissue osmotic pressure → further edema.

4. Lymphatic obstruction:

- Lymphatic obstruction causes lymphatic edema (lymphedema).

- It is caused by: 1- Lymphangitis and lymphadenitis as in Filariasis

→ elephantiasis. 3- Mechanical compression of lymphatics e.g. by tumors.

4- Lymphatic permeation by malignant cells. 5- Post-irradiation fibrosis in lymphatics & LNs. 6- Surgical removal of the lymph nodes.

* Classification of edema:1. According to the site of edema:

1. Localized edema: e.g inflammatory edema,

obstructive venous & lymphatic edema.

2. Generalized edema (anasarca):

– Cardiac edema: due to heart failure

– Renal edema: due to renal failure.

– Nutritional edema: due to hypoproteinemia.

2. According to consistency of edema:1. Pitting edema (Soft edema): in generalized

edema and obstructive venous edema.

2. Non-Pitting edema (Hard edema): e.g in

inflammatory edema and lymphatic edema.

Pitting edema• The accumulated fluid can be easily moved on pressing the affected part, leaving a pit at site of pressure (it pits on pressure).

• This is because the edema fluid has low protein content → it is present free in the tissue spaces.

Non-Pitting edema• The edematous part does not pit on pressure.• This is because the edema fluid is united with the

tissue elements.• Occurs in cases of lymphatic edema and

inflammatory edema.

References:Robbins and Cotran’s: Pathologic Basis of Disease.

Seventh edition.