There were a lot of people who suffered strokes during my visit to the hospital. Stroke is a sharp violation of the brain blood circulation; its symptoms remain for more than a day. The reasons of strokes among the patients I saw were different, starting from arteriosclerosis up to the deficiency of kidneys. The majority of such patients use different heart assist devices that help them to wait for a heart transplantation. Such devices allow a heart to rest and become stronger. Thus, the patients become stronger and healthier.
There are three types of stroke: ischemic stroke, hemorrhagic stroke and subarachnoid hemorrhage. The ischemic stroke most often develops during the narrowing or obstruction of arteries – vessels on which blood arrives to a brain. As a result, brain cells die without receiving the necessary oxygen and nutrients. Such a type of stroke is also called a brain attack by analogy to a heart attack. The reasons of a vessel obstruction can be different. The vessel can be closed in the embolus – the slices of the intra cardiac blood clot arising during some heart diseases – or the slices of the atherosclerotic plaque located on a wall of a large vessel. Thrombosis – a formation of a blood clot – can be the reason of such vessels obstruction. A blood clot is usually formed on a surface of an atherosclerotic plaque. Thrombosis is promoted by the increase of coagulability of blood and the increased ability to adhesion (aggregation) of blood plates (platelets).
Sometimes a stroke develops even at the absence of full vessels obstruction when there is only expressed stenosis – a narrowing of vessels walls by an atherosclerotic plaque by 70-90%. Blood, arriving in a brain on the narrowed vessel at a sudden fall of arterial pressure, is not enough for a normal brain supply; therefore, a stroke develops. The changes of the walls of small vessels that feed deep brain structures can develop at a frequent increase of arterial pressure. These changes lead to narrowing and often to the closing of these vessels.
A critical illness myopathy (CIM) stroke is a hereditary illness, during the course of which the muscles are not capable to relax normally after the contraction; it leads to muscles weakness, muscular spasms and shortening of muscles (contractures). A CIM stroke is accompanied by the weakness and rigidity of muscles, especially hand muscles. Ptosis is another common symptom of a CIM stroke. This illness can emerge at any age and vary in its severity. The evere form of a CIM stroke includes a critical muscular weakness and many other symptoms, including a cataract, dystrophy of small eggs, premature baldness, violations of a heart rhythm, diabetes, etc.
The occurrence of a CIM stroke leads to a long rehabilitation, formation of serious consequences, worsening of life quality and a raise of mortality rates. The main pathological mechanisms of a CIM stroke development are as follows: violation of electro excitability of tissues, microcirculation, hyperglycemia, activation of proteolysis, mitochondrial dysfunction, oxidatic stress, and production of pro-inflammatory cytokine. Early diagnostics, including clinical criteria, an electroneuromyography, and biopsies data allow correcting the tactics of the therapy of patients in order to prevent or minimize the CIM stroke manifestations.
Heart is affected by diabetes; the cardiac muscle changes at the expense of high sugar and cholesterol levels; this situation leads to a stroke and a lack of blood-groove. Moreover, the defeat of a nervous system causes the violation of blood pressure and an autonomous neuropathy of heart (what is shown in the form of the speeded-up pulse – tachycardia).
Diabetes harmfully influences the functioning of the whole organism. High blood pressure (hypertension) is the main risk factor leading to a stroke. Two people out of three, who suffer from diabetes, have high blood pressure. Many diabetics have strokes and fibrillation of auricles. Moreover, they have a high level of cholesterol in blood, which blocks blood vessels and leads to the reduction of a blood inflow to a brain. The smaller the access of blood to a brain is, the higher is the risk of a stroke. Damage to a brain can be even more serious and extensive if a sugar level in blood is very high during a stroke. In due course, a high maintenance of sugar in blood can lead to the development of problems with eyes, heart, blood vessels, nerves and kidneys. A high level of sugar also raises the probability of catching serious illnesses or infectious diseases.
Intracranial hematomas are blood congestions in a brain or between a brain and skull bones. Intracranial hematomas can result from a trauma or a stroke. The intra cranial hematomas caused by traumas are usually formed under an external (firm) cover of a brain (a subdural hematoma) or between an external cover and a skull (an epidural hematoma). Both types of hematomas are visible due to a computer tomography (CT) or magnetic and resonant tomography (MRT). Big hematomas put pressure on a brain, cause hypostasis and gradually destroy brain tissues. They can also lead to the impaction of an upper part of a brain or a brain trunk.
Heart assist devices are usually used to maintain the work of one of heart ventricles. This system includes a blades rotor, which rotates, thus creating a continuous stream of blood. The options of using similar heart assist devices can be considered on the example of applying the artificial left ventricles of heart (ALVH) as the most developed and demanded method of auxiliary blood circulation in the world cardiac practice.
According to Givertz:
Many different mechanical devices have been developed to support the failing heart, ranging from total artificial hearts to VADs. The main purpose of a VAD is to unload the failing heart and help maintain blood flow to vital organs. VADs were originally developed to serve as a temporary bridge to heart recovery, and then as a bridge to transplant. Over the past 10 years, however, VADs have been approved by the US Food and Drug Administration to provide permanent or lifetime support for patients with end-stage heart failure.
Patients with a critical heart function defeat, refractory to the medicinal influence, can consider three main ways of VAD systems usage.
- A peculiar mechanical “bridge” to the heart transplantation (87% of cases). This way of using VAD systems allows patients with quickly progressing heart failure to endure “the expectation period”.
- A temporary hemodynamic support, that allows overcoming the period of a sharply arisen heart failure, which cannot be treated by any other ways (9% of cases).
- A long-term replacement of the function of the heart’s left ventricle (4% of cases) is applied as an alternative to the method of heart transplantation, when there are certain contraindications or restrictions to its performance. In this case, a VAD system is implanted with a hope of long functioning.
The corresponding choice of VAD systems depends on a careful analysis of the reasons which result in a need of its use. There are no clear boundaries between the chosen options. At the solution of a question on the use of a certain option the patient is in the “intermediate” forms with a constant probability of transition from one state to another, depending on the clinical and technical conditions of the VAD systems.
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