HYPERTENSION [Symptoms /Etiology And Pathogenesis / Complication / Treatment / Symptoms / Causes]


        Hypertension is a serious medical condition that significantly increases the risks of heart, brain, kidney and other diseases. According to WHO, in 2015, worldwide 25% of makes and 20% of females were suffering from hypertension of these, only 20% of patients had BP under control. In India about 33% urban and 25% rural population is hypertensive. More worrying is the report that only one -tenth of rural and one-fifth of urban Indian hypertensive population have their BP under control. Hypertension is directly responsible for 57% of all stroke deaths and 24% of all coronary Heart disease deaths in India.


Definition

      Hypertension is defined as arterial blood pressure greater than 140mm/Hg and diastolic pressure greater than 90mm/Hg. Systolic pressure 120-140mm/Hg or diastolic pressure 80-90mm/Hg is known as prehypertension. In a vast majority of cases of hypertension, no definite cause can be detected. Such patients are said to suffer from "essential hypertension." In a small percentage of patients of hypertension, a definite cause can be found, such as kidney disease or and endocrine disorder. Such causes are said to suffer from secondary hypertension.

 Symptoms

       In most of cases of high blood pressure, there are no symptoms till the complications occur. When blood pressure very high, severe headache may be reported.

Etiology and Pathogenesis of essential hypertension 

      Blood pressure =cardiac output x peripheral resistance

                               = CO x PR 

      Regardless of the origin of hypertension, the actual increase in arterial blood pressure is caused by either an increase in peripheral vascular resistances [PR] or an increase in cardiac output [CO] the former is determined by the vascular tone.[eg; state of construction] of systemic resistance vessels, where as the later is determined by heart rate and stroke volume. In later stages of hypertension, only peripheral resistance is found to be increased; CO is normal.

1.Genetic predisposition.

2.Sympathetic Overactivity.

3.Role of sodium intake.

4.Vascular hyper-activity.

5.Renin-agniotensin-aldosterone-system[RAAS].

6.Endothelial dysfunction.   


Complications of untreated essential hypertension

1. Atherosclerosis

     Many of the complications of hypertension are related to the effects of sustained elevations of blood pressure on vasculature and heart. Atherosclerosis is commonly associated with and is accelerated by long-standing hypertension/ Most of the adverse outcomes in hypertension are associated with thrombosis rather then bleeding, Atherosclerosis predisposes the hypertensive patient to coronary thrombosis and cerebral stroke. Cerebral strokes are more often due to thrombosis rather than hemorrhage in the cerebral vessels. The excess morbidity and mortality related to hypertension are progressive over the whole range of systolic and diastolic blood pressures, and not limited to high values only. However, target-organ damage varies markedly between individuals with similar levels of hypertension. Atherosclerosis may also result in aortic aneurysm or peripheral arterial disease.

2. Hypertensive Cardiomyopathy

     Sustained increase in blood pressure (afterload) results in hypertrophy and subsequent dilatation of left ventricle. Electrocardiographic evidence of left ventricular hypertrophy is found in up to 15%of persons with chronic hypertension. Left ventricular hypertrophy may cause or facilitate many cardiac complications of hypertension, including myocardial ischemia, congestive heart failure, ventricular arrhythmias.

  👉 Cerebrovascular complications; Hypertension is an important risk factor for cerebral stroke. Approximately 85% of strokes are due to thrombosis and the remainder are due to hemorrhage in cerebral blood vessels.

     The term hypertensive encephalopathy is used to describe a group of symptoms and signs that sometimes follow a sudden and sustained rise of blood pressure. The symptoms are characterized by a severe headache, restless, impaired judgment and memory, confusion, somnolence and stupor. If the condition is not treated, these neurological symptoms may worsen and ultimately turn into a coma. Cerebral blood flow. The autoregulation seems to fail when hypertension becomes excessive.

  👉Retinopathy;  The primary response of the retinal arterioles to systemic hypertension is vasoconstriction. However, sustained hypertension leads to disruption of the blood-retinal barrier, increased vascular permeability and secondary arteriolosclerosis. Loss of vision may occur.

  👉 Renal complications; Renal failure is one of the important complications chronic hypertension. Sustained elevation of blood pressure damages renal microvasculature. Renal damages itself is a cause of hypertension (see secondary hypertensive below), starting a vicious cycle.

  👉Sexual dysfunction; Sexual dysfunction is more common and more severe in men with hypertension then it is in the general population. Hypertension is itself the major cause of erectile dysfunction. Experimental studies indicate that essential hypertension results in structural and functional changes in penile vasculature. Cavernous vessels are affected by chronic elevation of arterial blood pressure in the same fashion as other blood vessels. Marked hypertrophy in the smooth muscle of cavernous vessels, increased smooth muscle layer in cavernous space and increased extracellular matrix (collagen) explain the pathophysiological mechanism of erectile dysfunction in essential hypertension. 


Pathophysiological basis of treatment of essential hypertension  

  Non-pharmacological measures  

     * Reduction or elimination of factors such as stress, smoking, obesity

     * Regular aerobic exercise

     * Restriction of dietary calories, salt, cholesterol, and saturated fats 


Pharmacological measures

      A variety of drugs are being used in the treatment of essential hypertension. They reduce cardiac output, peripheral resistance or both.

Secondary hypertension 

     Secondary hypertension is defined as hypertension which is caused by an underlying well-defined primary cause. It is much less common than the essential hypertension, affecting only 5% of hypertensive patients. Some of the cause of secondary hypertension are treatable.




[CC= Cardiac contractility; VR= Venous return; SV= Stroke volume; EDV= End-diastolic volume; HR= Heart rate; PR= Peripheral resistance; CO= Cardiac output; CCB= Calcium channel blockers; ACALs= Angiotensin converting enzyme inhibitors]


Symptoms

     Like primary hypertension, secondary hypertension usually has no specific signs or symptoms, even if blood pressure has reached dangerously high levels.

Causes

      *Chronic kidney disease (chronic glomerulonephritis)

      *Renal artery stenosis

      *Cushing syndrome (increased secretion of cortisol by a tumor of adrenal cortex).

      *Aldosteronism (increased secretion of aldosterone by a tumor of adrenal cortex).

      *Pheochromocytoma (increased secretion norepinephrine and epinephrine by a tumor of adrenal medulla).

     *Coarctation of the aorta; There is congenital narrowing (coarctation) in the thoracic aorta. Hypertension is recorded in upper part of the body only.