Systemic Hypertension:

Persistent systolic pressure, more than 140 and diastolic pressure more than 90 mm Hg. is regarded as hypertension.

The frequency of hypertension increases steadily with age.

It is frequently stated that the disease is more common in women than in men (in a ratio of 2:1).

Systemic hypertension is classified into two main groups according to the cause, as follows:

I -  Idiopathic, primary or essential hypertension - 90 to 95% cases. The cause is obscure. It is further subdivided into the more frequent benign and the less common malignant varieties.

II - Secondary hypertension - Caused by known disease of renal and extra-renal nature.

Essential hypertension is the most important cause of coronary heart disease and cerebrovascular accidents. It is also responsible for the congestive heart failure, renal failure and aortic diseases.

Blood pressure is maintained by the interaction of multiple genetic and environmental factors.

It is dependant on cardiac output and peripheral vasoconstriction. 

Vasoconstriction increases peripheral resistance. Important vasoconstrictors are angiotensin-II, catecholamines etc.

Renal mechanisms regulate blood pressure. Eg: The renin-angiotensin system (regulated by gene-encoding angiotensinogen, the physiologic substrate of renin).

Sodium homeostasis also regulates blood volume and cardiac output.

Systemic Hypertensive Heart Disease:

Hypertensive heart disease is an important and common form of heart disease.

Features:

- Patient has a history of hypertension.

- Left ventricular hypertrophy, concentric type.

- Absence of other lesions that might induce cardiac hypertrophy. Eg: Aortic valve stenosis .

Pathogenesis:

There is myocytic hypertrophy in response to the increased work.

Thickened myocardium reduces left ventricle compliance, impairing diastolic filling.

Individual myocyte hypertrophy increases the distance for oxygen and nutrient diffusion from adjacent capillaries.

In a significant number of patients there is associated coronary atherosclerosis accompanying hypertension which may further lead to ischemia.

Gross features:  Image Link1   ;  Image Link2

Thickened left ventricle wall with increased heart weight. The left ventricle wall thickness is usually more than 2cm wall thickness.  The average heart weight is 500 to 600 gm. It may be as much as 1100gm.

The papillary muscle and trabeculae carneae are rounded and prominent and cardiac chamber is small (concentric hypertrophy).

When cardiac failure ensues, dilatation of the chamber also may be prominent.

Endocardial fibrous thickening may be present in the left ventricle in instances of long-standing hypertension.

After the onset of left ventricular failure, there may be dilatation and hypertrophy of the right side of the heart.

Microscopic features: Image Link

Myocytes and nuclei are enlarged.

In long-term cases diffuse interstitial fibrosis and focal myocyte atrophy and degeneration may develop, with left ventricle chamber dilatation and wall thinning.

Myocardial edema and foci of necrosis characterized either by intense eosinophilia or by complete dissolution of the muscle fibers occur in malignant hypertension.

Fate: 

Patients die of congestive heart failure ;

Complications of coronary artery disease, such as myocardial infarction can occur ;

There is increased risk of sudden death ; 

Some patients die of renal disease, stroke etc. ;

Fibrinous pericarditis may be evident in patients who die as a result of uraemia  ;

Therapeutic control of pressure may, lead to regression of the enlarged myocytes and reduction of heart size.