This does not mean that because of the heat you suddenly become ill from hypertension or coronary artery disease, but simply increased risk of exacerbation of existing disease to extremes - a stroke or heart attack. In the heat load on the heart and blood vessels increases, and "bottlenecks" in the circulatory system can suddenly make itself known. Suddenly, in full, as cardiovascular diseases often develop without symptoms - until a certain time.
This is because the root of the majority of such diseases is the same - atherosclerosis, i.e., narrowing of the blood vessels. And it also happens that the symptoms of atherosclerosis are beginning to be felt only when the lumen of the vessel closes by 75%!
For people older than 65 years, atherosclerosis is the most common cause of death. The death of more than 50% of people aged 60-70 years, due to the manifestation of certain types of atherosclerosis. The most common manifestations of atherosclerosis, enshrined in hospitals are myocardial infarction or stroke. Atherosclerosis is also often the cause of pain in the legs when walking.
For a long time it was believed that atherosclerosis is a lot of old people. But in recent years and in 20-years young people, doctors detect atherosclerotic plaques in blood vessels that cover 20% of the arteries. Atherosclerosis is accompanied by a whole bunch of diseases - from vascular dystonia ending cardiosclerosis and sclerosis of cerebral vessels.
I say "accompanied" but not "caused by atherosclerosis," because not all of these diseases are due to narrowing of the arteries. Some of them are developed in parallel, having a common cause with atherosclerosis - an increased level of free radicals in combination with the weakening of the antioxidant defense of the body. Therefore, atherosclerosis, and coronary heart disease, hypertension, VVD, thrombosis, varicosis, and even such diseases as diabetes, glaucoma, cataracts and cancer, are recently assigned to a new class of free radical diseases.
I have written about the causes of atherosclerosis and the dangers of free radicals (for example, in the article "How to tame cholesterol?". Here I want to place some important, in my opinion, accents.
Thus, as the main causes of atherosclerosis medicine names the following:
1) Elevated blood levels of lipoproteins of low and very low density (LDL and VLDL). These are what we call "bad cholesterol". They are the material for the initial formation of atherosclerotic plaques on the vessel walls. Therefore they are also called cholesteric plaques.
2) An excess amount of free radicals - active oxygen ions - in the blood. The excess of active oxygen forms are very dangerous for the organism, because they destroy the cell membranes and intracellular structures, until the DNA, leading to mutations and cell death. But in this case it is important that the free radicals oxidize blood lipids (the same "bad cholesterol"), but only oxidized cholesterol molecules able to attach to vessel walls. Therefore, an excess of free radicals is the "trigger" that turns on the mechanism of atherosclerosis development.
Doctors argue about the mechanism of cholesterol molecules attaching to the walls of blood vessels. According to one hypothesis, oxidized LDL deposite on the vessels epithelium and due to its cytotoxic properties penetrate deep into the arterial wall. According to another version, the cause of subsidence are chronic damage to the epithelium and endothelium that lead to chemotactic attraction of platelets and cholesterol molecules. But in fact, in both embodiments, the main damaging factor is free radicals.
That's because the blood, which is, generally speaking, a slurry of red blood cells in the plasma fluid moves freely through the vessels for one reason only: the red blood cells as well as the epithelium of the vessel walls have a weak negative charge, causing them to repel each other.
Excess, above permitted free radicals lacking one or more electrons, take away the excess charge of red blood cells and make them electrically neutral. Electroneutrality particles no longer repel each other but stick together in clumps (or "pillars"), consisting of tens or even hundreds of blood cells.
The same story happens also to the cholesterol molecules. And if, in addition, on some sections of the vessels, the surface charge of the epithelium will be also neutralized, such sections attract cholesterol, and red blood cells, and platelets, forming a very real "dirt".
This "dirt" is not so easy to wash, because it penetrates through the epithelium and incorporates into the structure of the vascular wall, forming a so-called "foam cells" (macrophages).These cells, which accumulate oxidized lipids, just are germs of atherosclerotic plaques.
Naturally, appeared plaques are the areas of the further accumulation of material, resulting the plaque becomes a protuberance protruding into the lumen of the vessel. Here we have the embryo of a blood clot.The gradual growth of atherosclerotic plaques in the end can lead, sometimes after many years, to a pronounced stenosis (narrowing of the lumen) of the vessel or its complete blockage.
When elevated levels of free radicals, blood pH changes - the blood becomes more "acidic". As a result, circulating calcium ions form poorly soluble salts which are deposited on the vessel walls, primarily, of course, in the "special points", that is, on the surface of the plaques.
These calcified plaques are, in fact, "stalactites", which are almost impossible to remove. Because of these plaques, people go on an operation to bypass the coronary vessels. In 1995, it was carried out such operations in America totaling more than $ 50 billion.
Sometimes also there is the case of spontaneous cracking or rupture of calcified plaque that stimulates the formation of blood clots. This may cause embolism, rapid clogging of the lumen or sticking thrombus to the plaque and thereby increase its volume.
It should be emphasized that the degree of calcification of arteries is no way related to calcium content in the body. Calcium in this case is "guilty without guilt", as its concentration in the blood is maintained strictly constant, at the level of 1%.
Free radicals threaten not only the arteries, but on the sly "enclose a bomb" under all the blood vessels, in the first place, the capillaries. This is due to the fact that the coalesced erythrocytes just can not pass into the lumen of the capillary, and hence perfusion of individual sections of tissues deteriorates. There is a condition that is diagnosed as vegetative-vascular dystonia (VVD) and its manifestations can be very different.
When it comes to the vessels of the upper and lower limbs - we have Raynaud's disease (spasm of the small arteries in the arms), or intermittent claudication. If that are the eyes - glaucoma or cataracts. If the auditory organs - Meniere's disease; brain - migraine, senile (in old people) or any other brain dysfunctions, without regard to age.
VVD manifestations are general innumerable, as it can cause hypoxia of any organ tissues. And if you feel causeless shortness of breath, fatigue, tremors in the hands and feet, it can be a sign of vascular dystonia. And action must be taken immediately, while there is the time, as this is a sign that your body is in a state of oxidative stress. If you carefully read the article up to this point, you should clearly see the logical outcome of this process.
Here is the small, particular conclusion from the above scheme: varicosis - the bane of many women - can also be the result of VVD. Deterioration of capillary permeability disrupts the work of "second heart" - vascular muscle in the capillaries of the lower limbs.