Diseases of the Blood Vessels

 

Arteriosclerosis  is hardening of the arteries.  This occurs with aging as the elastic fiber of the tunica intima is replaced with non-elastic collagen.  Arteries become brittle and are subject to rupture.

 

Atherosclerosis occurs when fat-cholesterol deposits called plaque form within the walls of arteries.  This narrows the opening and may completely occlude it.  Occlusions will prevent the blood from reaching the organs supplied by that vessel.  This produces a condition known as ischemia and can lead to a myocardial infarction (heart attack) or a stroke (cerebrovascular accident – CVA).

 

Thrombosis and Embolism

 

When you are cut, excessive loss of blood is prevented by the formation of a clot or thrombus.  Clots can also form inside intact blood vessels.  Clots tend to form in vessels where blood flows more slowly, as in veins.  Another frequent site of clot formation is in the area of heart valves that are damaged. 

            Platelets are cellular fragments that initiate clotting when they clump together.  This clumping is favored by atherosclerotic plaque, heart damage due to Rheumatic fever and inflamed walls of veins (Phlebitis).  Certain medications, such as aspirin and Ibuprofen, interfere with clot formation by inhibiting the clumping of platelets.

Phlebitis is the inflammation of the inner lining of a vein which results from infection, poor circulation and obesity.  In the deep veins of the leg, this inflammation can lead to thrombus formation.  This will prevent the proper return of blood to the heart.  If the thrombus becomes dislodged it can travel to the heart as an embolism or moving clot.  From the heart, the embolism can travel to the lungs and block a pulmonary artery (pulmonary embolism).  This interferes with the oxygenation of the blood.

 

Aneurysm is a weakening in the wall of a blood vessel, typically an artery.  A person may be born with this defect (congenital) or it may develop from atherosclerosis.  As it increases in size it may rupture.  If the aneurysm is located in the aorta, coronary artery or a cerebral artery and ruptures, the resulting loss of blood (hemorrhage) will lead to an infarct (dead region) in vital organs.

 

Varicose veins form in superficial veins of the leg, ankle and foot.  When blood cannot effectively return to the heart form the lower extremities, these veins become swollen, painful and show a knot-like appearance under the skin.  Normally, the contractions of the leg muscles (muscle pumps) help to “milk” the blood upwards from one venous valve to the next.

            When individuals remain seated for long periods, blood tends to pool in these veins.  Fluid leaks from the vessels into the surrounding tissues.  Persons on long duration air travel will see an accumulation of fluid around their ankles and feet.  Passengers are advised to stand, walk and use their leg muscles to help return blood to the heart. 

 

Hemorrhoids are varicose veins of the rectum and anus.  They often develop to the straining defection of constipation.  They also develop in women during pregnancy. 

 

Hypertension or high blood pressure is called the silent killer.  It is the leading cause of stroke (CVA) and congestive heart failure.  Risk factors for hypertension are; obesity, smoking, high salt intake, high intake of lipid and cholesterol.  There are also hereditary factors that may predispose for high blood pressure.  The pressure of the blood depends on two major components:

  1. Cardiac output – which is the amount of blood pumped out of the heart each minute.
  2. The peripheral resistance is the back pressure on the blood due to the inner diameter of the arteries and their flexibility.  Arteriosclerosis and atherosclerosis will both increase peripheral resistance.

 

Hypertension and Kidney Disease

 

            As kidney function decreases with age, water and salt retention increases.  This elevates blood pressure and leads to hypertension.  On the other hand, long standing hypertension produces arteriosclerosis of the renal arteries.  This reduces blood flow to the kidneys and damages them.  In addition, the kidneys respond to the reduced blood flow by releasing a substance the triggers very high blood pressure throughout the body (renal hypertension).

 

Effects of Hypertension

 

  1. Causes the heart, especially the left ventricle to overwork.  This leads to enlargement (hypertrophy) of the left ventricle without an increase in blood supple to the myocardium.  This can lead to angina and heart failure.
  2. Hypertension causes arteriosclerosis within arteries throughout the body.  The increased pressure and reduced elasticity of the arteries favors the rupture of arteries and clot formation.
  3. Hypertension tends to damage and debilitate all major organ systems of the body.

 

Treatment for Hypertension

 

  1. Use of diuretics reduces blood pressure by increasing water loss through the kidneys.
  2. Reduced salt intake decreases water retention reducing blood pressure directly.
  3. Exercise improves circulation especially return of blood from the veins back to the heart.  Increased physical activity also slows the progress of arteriosclerosis.
  4. Dietary reduction of cholesterol and fats will slow the onset and may even reverse atherosclerosis.

 

Shock is a vascular response to physical or psychological trauma.  In general, blood pressure and venous return are reduced dramatically.  There are different forms of shock:

  1. Hypovolemic shock – results from hemorrhage.  Treatment involves blood or plasma replacement by transfusion.  In some cases, severe dehydration can produce hypovolemic shock.
  2. Neurogenic shock –  is produced by a generalized vasodilation as a result of a loss of muscle tone in the walls of arteries.  This conditioned has been procuced by spinal anesthesia and toxins.
  3. Anaphylactic shock – often follows severe allergic reactions resulting from incompatible blood transfusions, venomous insect bites or eating foods that are allergenic such as shellfish and peanuts.
  4. Cardiogenic shock – can follow a myocardial infarction.  The inadequate pumping of the heart produces a profound decrease in blood pressure.