Essential Hypertension Definition

Definition of High blood pressure or Hypertension is the elevation of systolic and or diastolic blood pressure greater than 150/90 mm Hg. There are two types of hypertension; Essential hypertension (primary hypertension) and inessential hypertension (commonly known as secondary hypertension). Essential Hypertension (about 90 percent of all hypertension cases), most people with essential hypertension show heightened vascular and cardiac reactions to sympathetic stimuli. Whether this hyper responsiveness resides in the sympathetic nervous system, its receptors, or the tissue that it innervates is not know. Secondary hypertension is associated with bilateral renal parenchymal disease or with such potentially curable disorders as pheochromocytoma, Cushing's syndrome, primary aldosteronism, hyperthyroidism, myxedema, coarctation of the aortha, renal vascular disease, and unilateral renal disease.

Pathology

No pathologic changes occur early in essential hypertension. Ultimately, generalized arteriolar sclerosis develops. Its particularly apparent in kidney and is characterized by intimal hyalinization and medical hypertrophy. Nephrosclerosis in the hallmark of primary hypertension. Left ventricular hypertrophy and, eventually, dilation develops gradually. Coronary, cerebral, aortic, renal and peripheral atherosclerosis are more common and more severe in hypertensives since hypertension accelerates atherogenesis.

Maligant hypertension is characterized by widespread necrotizing arteriolitis with fibrinoid changes and proliferative endarteritis, especially in, but nor confine to, the kidney.

Pathophysiology

Not all patients with essential hypertension have normal cardiac output and increased peripheral resistance. Cardiac output is increased and peripheral resistance is inappropriately normal for the level cardiac output in the early labile phase of essential hypertension. Peripheral resistance increases and the cardiac output returns to normal after a period of time, probably because of auto-regulation. Patients with high fixed diastolic pressures often have decreased cardiac output. The role of the large veins in the pathophysiology of essential hypertension has largely been ignored, but venoconstriction early in the course of the disease may contribute to the increased cardiac output.

Relationship between Hypertension and Plasma Volume

Plasma volume tends to decrease as Blood pressure increases, although some people with primary hypertension have expanded plasma volumes. Plasma renin activity is usually normal but may be suppressed in some and elevated in others. The accelerated malignant phase of hypertension is usually accompanied by elevated plasma renin activity.

Systolic Hypertension

Systolic hypertension with normal diastolic pressure is not a discrete entity. This conditions often result of increased cardiac output or stroke volume, in the elderly (with normal or low cardiac output), systolic hypertension usually reflects inelasticity of the aorta and its major branches.

Symptoms and Signs

Primary hypertension is asymptomatic until complications develop. Hypertension symptoms and signs are nonspecific and arise from complications in target organ. Non complication hypertension may cause dizziness, flushed facies, headache, fatigue, epistaxis and nervousness. Hypertension with complications include left ventricular failure, atherosclerotic heart disease, retinal hemorrhages, and vascular accidents.