Heart and Vascular Diseases

The heart is subject to various pathological changes that prevent it from fulfilling its role as a pump. In a person who is in poor physical condition, heavy muscular work can strain and damage the heart muscle and reduce its ability to contract. The vessels supplying the heart muscle with blood may become blocked by a blood clot or some other body, which prevents the delivery of nutrients and oxygen and can cause a “heart attack.”

If the area of ​​the heart served by the blocked vessel is not too large, then the attack will not be fatal; but if a sufficiently large area is affected, death occurs within a few minutes. The causative agents of some diseases, such as diphtheria, release toxic substances that travel through the blood into the heart and damage the heart muscle. Excess thyroid hormone causes the atria to contract uncoordinatedly, which reduces the efficiency of the heart.

Sometimes heart valves damaged by pathogens (such as syphilis or rheumatism) fail to close properly, causing blood to leak back after the heart beats. To compensate for this defect, the heart often enlarges, increasing its ability to pump blood. Rheumatism, especially common in young people, is dangerous not only because of the infection of the joints, but also because it affects the heart.

As the body ages, the walls of the arteries tend to lose elasticity, become harder and denser, and the lumen of the vessels decreases. Less blood flows to the organs, which leads to disruption of their function. Typically, hardening of the arteries is accompanied by an increase in blood pressure: vessels that have lost their elasticity are not able to expand and contract with each contraction of the heart, and the heart has to develop greater force to push blood through them.

High blood pressure can also be caused by other disorders, such as kidney disease. This condition is serious because the excessive increase in pressure can lead to rupture of the blood vessel. Usually a small vessel ruptures and blood loss is insignificant.

But bleeding into soft tissue such as the brain can cause cell damage, leading to paralysis of the muscles the cells serve and sometimes death. High blood pressure can lead to heart failure because the heart muscle is unable to overcome the increased resistance of hardened arteries.

The veins sometimes become dilated and large amounts of blood stagnate in them (this condition is called varicose veins). Varicose veins almost always form in the legs and are most common in people who have to stand for long periods of time. Standing still further increases the pressure in the veins of the legs due to the lack of the "squeezing" action of the muscles that normally promotes proper blood flow. Varicose veins are more common in women than in men, due to the additional load on the circulatory system during pregnancy and childbirth.