Hypertension (HPT)

Definition: (National Heart, Lung & Blood Institute of U.S.A)

A sustained diastolic pressure greater than 89mmHg OR a sustained systolic pressure in excess of 139mmHg

----> increase risk of atherosclerosis
----> represent clinically significant HPT

*cut-off are arbitrary --->those with other risks of vascular disease (eg: DM), lower tresholds are applicable

Type & Causes of HPT

Essential (primary) HPT
-90-95% of cases
-idiopathic
-generally does not cause short-term problems unless MI, CVA/other complication supervenes.

Secondary HPT
-generally patient with underlying
1. Renal disease- acute glomerulonephritis, chronic renal disease, polycystic disease, renal artery stenosis, renal vasculitis & renin-producing tumor.
2. Endocrine disease/condition-adrenocortical hyperfunction, exogenous hormones (estrogen, glucocorticoids), pheochromocytoma, acromegaly hypothyroidism, hyperthyroidism & pregnancy-induced.
3. Cardiovascular disease- coarctation of aorta, polyarteritis nodosa, increased intravascular volume, increased cardiac output & rigidity of the aorta.
4. Neurologic condition- psychogenic, increased intracranial pressure, sleep apnea & acute stress.

Classification (according to presentation)

Benign HPT
-can be either essential/secondary
-when controlled, it is compatible with long life and is asymptomatic

Malignant (accelerated) HPT
-is a clinical syndrome of;
1. severe HPT (systolic BP >200mmHg, diastolic BP >120mmHg)
2. renal failure
3. retinal hemorrhage & exudate (with/without papilledema)
-may developed in either previously normotensive persons/ more commonly is superimposed on pre-existing benign HPT (either essential/secondary)

Normal BP regulation

Blood pressure is a function of two hemodynamic variables
1. cardiac output
2. peripheral vascular resistance

It is influenced by multiple genetic, environmental, and demographic factors

• age
• gender
• body mass index
• diet particularly sodium intake

Cardiac Output
- highly dependent on blood volume, itself greatly influenced by the sodium homeostasis.

Peripheral vascular resistance
- determined mainly at the level of the arterioles and is affected by neural and hormonal factors.




Atherosclerosis & HPT

Major Risk Factors for Atherosclerosis

nonmodifiable

• Increasing age
• Family history
• Male gender
• Genetic abnormalities

modifiable

• Hyperlipidemia
• Diabetes
• Hypertension
• C-reactive protein
• Cigarette smoking

Modifiable risk factors in IHD