and hypertensive heart disease

Chapter 41 Hypertension and hypertensive heart disease




Questions


image What are the main risk factors for hypertension?

image What changes are seen in the heart and blood vessels in hypertension?

image What are the pathological mechanisms involved in the development of hypertension?

Pathological increases in blood pressure can affect the systemic or pulmonary circulation and may be seen in the arteries or veins. Hypertension of the systemic arteries is covered here. It is a common health problem and is a risk factor for diseases that include atheroma, heart failure, aortic dissection and renal failure. Studies have shown that the risk of these complications increases as the blood pressure rises, and that antihypertensive treatment reduces the morbidity and mortality.


The definition of high blood pressure is arbitrary in that blood pressure exhibits a Gaussian distribution so there is no clear boundary between hypertension and normal blood pressure. In general, hypertension is commonly defined as a systolic blood pressure of 140mmHg or greater or a diastolic blood pressure of 90 mmHg or greater.


If untreated, hypertension can progress to malignant hypertension, which is defined as markedly elevated blood pressure (diastolic pressure usually >120mmHg). It is associated with rapid progression of target organ disease (e.g. renal failure and retinal damage).




Vascular changes in hypertension


The principal effect of hypertension in large and medium-sized arteries is to accelerate the development of atheroma. By comparison, arterioles exhibit two different kinds of morphological change in hypertension.


Hyaline arteriolosclerosis. This is an ageing-related change common in elderly individuals. However, it appears earlier in patients with either hypertension or diabetes. It is characterized by hyaline thickening of the walls of arterioles, with some luminal narrowing. It is believed to be caused by leakage of plasma proteins into the wall and increased production of extracellular matrix by smooth muscle cells in response to raised blood pressure.

Hyperplastic arteriolosclerosis. This condition is seen in more severe hypertension, including malignant hypertension. It is characterized by proliferation of smooth muscle cells and basement membrane material, causing concentric laminations. The result is progressive, severe narrowing of the lumen.


Regulation of normal blood pressure


Blood pressure is a function of cardiac output and peripheral resistance. Cardiac output is affected by the intravascular volume, while the peripheral resistance is controlled principally by arteriolar tone (Fig. 3.41.1).


image

Fig. 3.41.1 Summary of important factors involved in maintaining blood pressure. ACE, angiotensin-converting enzyme; GFR, glomerular filtration rate.

< div class='tao-gold-member'>

Related posts:

lung disease big picture heart disease factors in neoplasia of wounds and fractures and epidemiology of neoplasia

Stay updated, free articles. Join our Telegram channel
Tags:
Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on and hypertensive heart disease

Full access? Get Clinical Tree
Get Clinical Tree app for offline access