Cell pathology 2- Haemodynamic disorders

Question 1

Classify the cause of oedema (5)

Answer 1

Increased Capillary Hydrostatic Pressure
E.g. venous obstruction, congestive cardiac failure

Decreases Plasma osmotic Pressure

Inflammation
Increased vascular permeability facilitates movement of fluid into the interstitium

Lymphatic Obstruction
MOST COMMON - lymphoedema - breast cancer treatment - damage the lymph vessels leading to build up of fluid
Filariasis can cause massive lymphatic obstruction

Salt/H20 Retention

Question 2

Classify the causes(2) of generalised oedema and the consequences(2) in a periphral setting

Answer 2

Severe Generalised Oedema = Anasarca

It is the widespread accumulation of fluid in subcutaneous tissues and serous cavities

Common Causes:
Left Ventricular Failure - dependent oedema (accumulated in areas affected by gravity)

Nephrotic Syndrome - fluid accumulates in all parts of the body

Impaired wound healing
Patients with generalised oedema are more prone to getting cellulitis

Question 3

How can heart failure cause oedema

Answer 3

Low Renal Blood Flow

Release of Renin from kidneys

Formation of angiotensin II

Release of aldosterone from adrenal gland

Absorption of sodium and water from kidneys

Generalised oedema

Question 4

2 Causes of pulmonary oedema

Answer 4

Cause: Raised hydrostatic pressure in the pulmonary capillary bed

Most Common Cause of this: Left Ventricular Failure

Other causes= ARDS (Acute Respiratory Distress Syndrome)
Commonly seen in injecting drug users
Most Common causes of ARDS: Sepsis, Shock and Trauma

Can be chronic or acute

Question 5

How does left ventricular failure cause oedema

Answer 5

Left ventricular failure causes increased pressure in the left atrium

This causes back pressure into the capillaries

This pushes water into the interstitial space

Fluid accumulates in the interstitial space and then spills over into the alveolar spaces.

Question 6

Main symptom of pulmonary oedema

Answer 6

MAIN SYMPTOM: DYSPNOEA

Dyspnoea is worse when they lie flat because of the movement of fluid (this is called orthopnoea)

Fluid collection in alveolar spaces predisposes to bacterial infection in the lung (pneumonia)

Question 7

What are the 4 types of cerebral oedema

Answer 7

Vasogenic - physical breakdown of blood-brain barrier
Causes: Trauma and Tumours (by releasing factors which break down barriers)

Cytotoxic - derangement of sodium-potassium membrane pump
Common in ischaemic strokes
Increase in sodium within cells encourages water to be taken up
Causes intracellular oedema

Osmotic - reduction in plasma osmolality
Cause: SIADH (Syndrome of Inappropriate ADH secretion)
SIADH is commonly caused by SMALL CELL LUNG CARCINOMA
ADH release –> more water reabsorbed –> decrease in plasma osmolality

Interstitial - breakdown of CSF-brain barrier
Cause: Obstructive Hydrocephalus (abnormal accumulation of cerebrospinal fluid in the brain - due to blockage in flow of CSF)

CSF (NOT blood plasma) moves into the interstitial space

Question 8

What is thrombosis, what is the cause and what 3 factors predispose it

Answer 8

Abnormal blood clot formation in the circulatory system.

Caused by abnormal activation of the haemostatic system

3 factors (virchows triad)
Vessel wall injury
Changes in blood flow (stasis)
Changes in blood coagulability

Question 9

Describe cardiac thrombosis

Answer 9

STASIS is the main way that thromboses form

Left Atrial Thrombosis is usually related to atrial fibrillation

Left Ventricular Thrombosis is usually related to prior myocardial infarction

MOST IMPORTANT COMPLICATION: Systemic Embolisation

Question 10

Describe Arterial Thrombosis

Answer 10

Almost always related to vessel wall injury

Vessel wall injury is often caused by atherosclerotic plaques

Stenosis = narrowing of the artery by the thrombus
Stenosis causes ischaemia of the tissue supplied by the artery

Occlusion = complete blockage of the artery by the thrombus
Occlusion causes infarction of the tissue supplied by the artery

Question 11

Describe Venous Thrombosis

Answer 11

KEY FACTORS: Stasis and Hypercoagulability

Risk Factors: 
Age 
Obesity
Malignancy  
Immobility 
Oral Contraceptive Pill 

Most form in DEEP VEINS (DVT)

MOST IMPORTANT COMPLICATION: Pulmonary Embolism

Question 12

What are the 4 fates of the thrombus

Answer 12

Propagation-
Thrombus gets BIGGER - accumulates more fibrin and takes up a larger portion of the vessel

Embolisation-
Dislodges and travels to distant site

Dissolution-
Thrombus is destroyed by fibrinolytics (can be endogenous or given as a drug)

Organisation and Recanalisation-
As a result of the thrombus, there is inflammation `
Thrombus becomes fibrotic and remodels
Lumen appears again allowing blood flow

Question 13

What is an embolism

Answer 13

A detached intravascular solid, liquid or gaseous mass that is carried by the blood to a site distant from its point of origin.

Most emboli are fragments of dislodged thrombus (thromboemboli)

Note:
Rarer types of embolic material:  
Fat 
Air 
Amniotic Fluid 
Tumour

Question 14

Describe Arterial Thromboemboli

Answer 14

Most originate in CAROTID ARTERIES

Most likely to affect cerebral arteries - causing STROKE

Question 15

Describe Cardiac Thromboemboli

Answer 15

Most originate on the LEFT SIDE OF THE HEART

May lodge in:

Cerebral Artery - STROKE

Mesenteric Artery - BOWEL INFARCTION

Lower Limb Artery - ACUTE LOWER LIMB ISCHAEMIA

Question 16

Consequences of pulmonary embolism and what is the death rate

Answer 16

Emboli lodging in a major pulmonary artery can cause instantaneous death

If it gets lodged at the bifurcation of one pulmonary artery into two, it is called a saddle embolus

Emboli lodging in medium sized arteries present with breathlessness

Small emboli lodging in small arteries cause non-specific symptoms - e.g. dizziness, chest pain, breathlessness

30% of patients with PE die from it

Risk of death INCREASES with time taken to make the diagnosis

Question 17

What is a haemorrhage and what causes them

Answer 17

Haemorrhage can be external or enclosed within a tissue

Haematoma = a localised mass of extravasated blood that is relatively or completely confined within an organ or tissue

CAUSES:
Trauma
Intrinsic disease of the vessel

Question 18

What can occur when you have an acute haemorrhage in a major vessel

Answer 18

Hypovolaemia

Shock

Death

Question 19

What does a haematoma cause

Answer 19

Formation of a solid haematoma within the cranial cavity can be FATAL by causing a RISE IN INTRACRANIAL PRESSURE and TONSILLAR HERNIATION

Question 20

What is shock and how is it caused?

Answer 20

Generalised failure of tissue perfusion

Caused by a pump failure or peripheral circulation failure

Question 21

How do patients with shock appear and what symptoms do they have?

Answer 21

Grey and feel clammy

Tachycardia and hypotension

Question 22

What can untreated shock cause

Answer 22

Ischemia of heart, lungs, gut, and kidney

Question 23

5 types of shock

Answer 23

Hypovolaemic
Most commonly due to LOSS OF VOLUME

Cardiogenic
Due to IMPAIRED CARDIAC FUNCTION

Septic
Result of INFLAMMATORY RESPONSE

Anaphylactic
Result of IgE MEDIATED HYPERSENSITIVITY
AP

Neurogenic
RARE
Normally happens after trauma

Question 24

What is an infarction

Answer 24

Tissue necrosis due to ischaemia.

Most due to obstruction of an artery

Question 25

Describe red infarctions

Answer 25

haemorrhagic - affects organs with a dual blood supply - generally caused by venous blood supply `

Question 26

Describe white infarctions

Answer 26

anaemic - affects solid organs which have one blood supply

Question 27

Factors influencing the development of infarctions

Answer 27

Nature of Blood Supply:
If there is an obstruction in the lung or liver, they can use other vessels to supply the tissue.
Kidney and spleen are more susceptible to infarction

Rate of Development of Occlusion:
If the occlusion develops slowly, there could be enough time for Collateral Vessels to form and provide an alternate blood supply

Vulnerability to Hypoxia
EXAMPLE: neurones are very susceptible to hypoxia, fibroblasts aren’t

Oxygen content of the blood
EXAMPLE: patients who have anaemia and chronic heart failure will have reduced levels of oxygen in their blood - more prone to developing infarctions

Question 28

What are the twp types of myocardial infarction

Answer 28

Transmural Infarction
Entire wall is affected
Occurs when there has been complete blockage of a vessel and complete cessation of the blood supply

Subendocarial Infarction
Some myocardial tissue underneath the endocardium has been affected by infarction
Caused by drop in blood oxygen content or rapid drop in blood supply (e.g. due to blood loss)

Question 29

What is Atherosclerosis

Answer 29

Complex chronic disease - underlying cause of most vascular diseases

Focal intimal accumulation of lipids and fibrous tissue associated with smooth muscle proliferation

Affects medium and large vessels

Develops from fatty streak into plaque within the intima

Question 30

What is the Process of Atherosclerosis (7)

Answer 30

Endothelial damage
macrophages release cytokines
Cytokines recruit LDLs
LDLs become oxidised
Oxidised LDLs are pro-inflammatory and drive progression of plaque
Smooth muscle cells migrate from the tunica media to the lesion
Smooth muscle cells deposit a collagen rich matrix that forms a protective fibrous cap

Question 31

Diseases caused by stable atherosclerotic plaques:

Answer 31

Stable angina

Chronic lower limb ischaemia

Question 32

Diseases caused by thrombosis overlying an unstable atherosclerotic

Answer 32

Unstable angina

Myocardial infarction

Cerebral infarction

Acute lower limb infarction