HYPERTENSIVE VASCULAR DISEASE 

Malignant hypertension 
A small percentage of HTN patients (5%) present with a rapidly rising blood pressure that, if untreated, leads to death within 1 to 2 years. 

systolic pressures -> 200 mm Hg or diastolic pressures -> 120 mm Hg 
Associated with renal failure and retinal hemorrhages
Most commonly is superimposed on preexisting benign hypertension

Hypertension (HTN) has the following complications

- stroke (CVD) 
- multi-infarct dementia
- atherosclerotic coronary heart disease 
- cardiac hypertrophy and heart failure (hypertensive heart disease) 
- aortic dissection 
- renal failure

Essential HTN Accounts for 90% to 95% of all cases

SecondaryHTN 

Renal - > Acute glomerulonephritis Chronic renal disease 
Endocrine - >  Cushing syndrome, Hypothyroidism (myxedema) Hyperthyroidism (thyrotoxicosis) Pregnancy-induced (pre-eclampsia)
Cardiovascular  - > Coarctation of aorta 

Neurologic

Psychogenic,  Increased intracranial pressure 

PATHOGENESIS
most cases (95%) are idiopathic (essential hypertension)
Most of the remaining cases (secondary hypertension) are due to primary renal disease, renal artery narrowing 
Gene defects in enzymes involved in aldosterone metabolism 
 Mutations in proteins that affect sodium resorption as in Liddle syndrome
 
 Genetic factors - > familial clustering of hypertension 
 
 Environmental factors such as stress, obesity, smoking, physical inactivity, and high levels of salt consumption, modify the impact of genetic determinants

Morphology
HTN is associated with arteriolosclerosis (small arterial disease) 

Two forms of small blood vessel disease are hypertension-related: 
1- hyaline arteriolosclerosis 
2- hyperplastic arteriolosclerosis 

Hyaline arteriolosclerosis
Associated with benign hypertension. 
-marked by homogeneous, pink hyaline thickening of the arteriolar walls, and luminal narrowing. 

Hyperplastic arteriolosclerosis
It is more typical of severe hypertension. 
- "onionskin," concentric, laminated thickening of arteriolar walls and luminal narrowing. 
- The laminations consist of smooth muscle cells and thickened, reduplicated basement membrane. 

DISORDERS OF BLOOD VESSEL HYPERREACTIVITY
Several disorders are characterized by inappropriate or exaggerated vasoconstriction of blood vessels: 
1- Raynaud Phenomenon 
2- Myocardial Vessel Vasospasm 

Raynaud Phenomenon
- results from exaggerated vasoconstriction of arteries and arterioles in the extremities (the fingers and toes, but also sometimes the nose, earlobes, or lips). 
-restricted blood flow induces paroxysmal pallor or cyanosis
- involved digits characteristically show "red-white-andblue" color changes from most proximal to most distal 

Myocardial Vessel Vasospasm 

Causes: 1- vasoactive mediators - > prolonged vascular contraction; 
- endogenous (e.g., epinephrine released by pheochromocytomas) or exogenous (cocaine or phenylephrine). 
2- Elevated thyroid hormone -> increase sensitivity of vessels to catecholamines 
3- autoantibodies and T cells in scleroderma vascular instability and vasospasm. 
4- extreme psychological stress (release of catecholamines)

Cardiac raynaud

When vasospasm of cardiac arterial or arteriolar bed is of sufficient duration (20 to 30 min ) myocardial infarction occurs

acute microscopic area of necrosis characterized by mycotic hypercontraction (contraction band necrosis)

subacute and chronic cases - > microscopic foci of granulation tissue or scar

HYPERPLASIA
It is the increase in the size of an organ or tissue due to increase in the number of its constituent cells. This is seen in organs made up of labile and stable cells.

Causes
I. Increased demand:
- Bone marrow in hypoxia and haemolytic states.
- Thyroid gland in puberty

2. Persistant Trauma:
- Acanthosis of the epidermis in chronic inflammations and in warts.
- Hyperplasia of oral mucosa due tooth and denture trauma.
- Mucosa at the edges of a gastric ulcer.

3. Endocrine target organ:
- Pregnancy hyperplasia of breast.
- Prostatic hyperplasia.

4. Compensatory:

Hyperplasia of kidney when the other kidney has been removed.

5. Idiopathic:
Endocrine organs like thyroid, adrenals, pituitary etc. can undergo hyperplasia with no detectable stimulus. .
 

Paget Disease (Osteitis Deformans) 

This unique bone disease is characterized by repetitive episodes of exaggerated, regional osteoclastic activity (osteolytic stage), followed by exuberant bone formation (mixed osteoclastic-osteoblastic stage), and finally by exhaustion of cellular activity (osteosclerotic stage). The net effect of this process is a gain in bone mass; however, the newly formed bone is disordered and lacks strength. Paget disease usually does not occur until mid-adulthood but becomes progressively more common thereafter. The pathognomonic histologic feature is a mosaic pattern of lamellar bone (likened to a jigsaw puzzle) due to prominent cement lines that haphazardly fuse units of lamellar bone. (Fig. 12-5) The axial skeleton and proximal femur are involved in the majority of cases. In patients with extensive disease, hypervascularity of the marrow spaces can result in high-output congestive heart failure. Cranial nerves impingement also occurs and can lead to head ache and auditory disturbances. Rarely Paget disease is complicated by bone sarcoma (usually osteogenic). 

Clinical & biologic death

Clinical death

Clinical death is the reversible transmission between life and biologic death. Clinical death is defined as the period of respiratory, circulatory and brain arrest during which initiation of resuscitation can lead to recovery.

Signs indicating clinical death are

• The patient is without pulse or blood pressure and is completely unresponsive to the most painful stimulus.

• The pupils are widely dilated

• Some reflex reactions to external stimulation are preserved. For example, during intubations, respiration may be restored in response to stimulation of the receptors of the superior laryngeal nerve, the nucleus of which is located in the medulla oblongata near the respiratory center.

• Recovery can occur with resuscitation. 

Biological Death

Biological death (sure sign of death), which sets in after clinical death, is an irreversible state

of cellular destruction. It manifests with irreversible cessation of circulatory and respiratory

functions, or irreversible cessation of all functions of the entire brain, including brain stem.

Langerhans cell granulomatosis (histocytosis X)
a. A group of diseases that are caused by the proliferation of Langerhans’ cells (previously known as histocytes).
b. Most commonly causes bone lesions; however, other tissues can be affected.
c. Histologic findings include Langerhans’ cells containing Birbeck granules and eosinophils.

d. Three types:
(1) Letterer-Siwe disease—an acute, disseminated form that is fatal in infants.
(2) Hand-Schüller-Christian disease—a chronic, disseminated form that has a better prognosis than LettererSiwe disease. It usually presents
before the age of 5 and is characterized by a triad of symptoms:
(a) Bone lesions—found in skull, mandible (loose teeth).
(b) Exophthalmos.
(c) Diabetes insipidus.
(3) Eosinophilic granuloma of bone—a localized, least severe form of the three. Lesions may heal without treatment.
(a) Most commonly occurs in young adults.
(b) Lesions in the mandible may cause loose teeth.

Pleural effusion is a medical condition where fluid accumulates in the pleural cavity which surrounds the lungs, making it hard to breathe.

Four main types of fluids can accumulate in the pleural space:

Serous fluid (hydrothorax)

Blood (hemothorax)

Lipid (chylothorax)

Pus (pyothorax or empyema)

Causes:

Pleural effusion can result from reasons such as:

• Cancer, including lung cancer or breast cancer
• Infection such as pneumonia or tuberculosis
• Autoimmune disease such as lupus erythematosus
• Heart failure
• Bleeding, often due to chest trauma (hemothorax)
• Low oncotic pressure of the blood plasma
• lymphatic obstruction
• Accidental infusion of fluids

Congestive heart failure, bacterial pneumonia and lung cancer constitute the vast majority of causes in the developed countries, although tuberculosis is a common cause in the developing world.

Diagnosis:

1. Gram stain and culture - identifies bacterial infections
2. Cell count and differential - differentiates exudative from transudative effusions
3. Cytology - identifies cancer cells, may also identify some infective organisms
4. Chemical composition including protein, lactate dehydrogenase, amylase, pH and glucose - differentiates exudative from transudative effusions
5. Other tests as suggested by the clinical situation - lipids, fungal culture, viral culture, specific immunoglobulins