Introduction
The heart action is divided into two phases: the expulsion phase, known as systole, and the filling phase, known as diastole. The causes of low diastole are many and varied, although there are also many harmless reasons that require treatment, which should be clarified with a doctor. Very often, however, a low diastolic value is related to a generally low blood pressure and does not represent a danger. By definition, diastolic blood pressure is too low if the value is below 60 mmHg.
Causes of a too low diastole
The most common causes of decreased diastole are listed below. You will then find a more detailed explanation of the clinical pictures.
- Hypotension
- Varicose Veins
- Heart failure
- Heart valve defect
- Orthostatic neuropathies
- Drugs
- Decreased blood pressure during pregnancy
There are many causes for hypotension, most often it is idiopathic.
This means that no cause can be found. It mainly affects younger women with slim, dainty physiques and is favored by infections and lack of exercise, e.g. immediately after an operation. If there is no idiopathic cause, it is called secondary hypotension.
It can in turn have various causes. One of them is a blood volume that is too small for the vessel size. This can be an absolute lack of fluid, e.g. after severe blood loss or a relative deficiency.
This means that although there is enough fluid in the body overall, it is distributed to the disadvantage of the organ systems. This is the case, for example, in allergic shock, when blood migrates to the periphery (skin) and there is too little blood for the central organs to maintain normal blood pressure. The thyroid gland intervenes in blood pressure regulation.
The thyroid gland produces the hormones T3 (triiodothyroxine) and T4 (thyroxine). These two hormones have a very diverse function in the body and act on many organs. In general, they stimulate the metabolism and thus increase energy and oxygen consumption.
The thyroid hormones also have an effect on the heart. This is where so-called beta receptors are located, which are increasingly integrated into the surface of the heart muscle cells under the influence of T3 and T4. When activated, these beta receptors increase the contractile force of the heart, which is of decisive importance for increasing blood pressure, among other things.
A further point of attack of the thyroid hormones are the walls of the blood vessels, which dilate under their influence (so-called vasodilation) and thus lower the blood pressure. In people with hyperthyroidism, an excess of hormones is produced. As a result, an increased number of beta receptors are presented on the surface of the heart cells and the systolic value increases in those affected.
The increased hormone level simultaneously dilates the vessels and reduces the diastolic value. As a result, people with hyperthyroidism often have a wider range between systolic and diastolic blood pressure values. Hypothyroidism usually manifests itself in the opposite way, i.e. a decrease in systolic and an increase in diastolic values.
Cardiovascular disease can also be responsible for hypotension. On the one hand, this can be heart failure, i.e. the heart as a “pump” is broken and therefore ineffective. Less and less blood is being expelled and, as a result, blood pressure drops over time when it can no longer be compensated by other mechanisms.
However, heart valve defects can also be responsible for arterial hypotension. Diastolic hypotension is particularly typical for aortic valve insufficiency. The valve separates the left chamber from the aorta and ensures that no blood flows back from the aorta into the heart during diastole (filling phase).
If the valve becomes permeable (insufficient), blood flows back into the heart with the result that the diastolic blood pressure drops. Furthermore, low blood pressure can be caused by insufficient venous blood flow back to the heart. This is the case with varicose veins, for example.
The blood can no longer drain off properly and accumulates in the legs, with the result that this volume is missing from the other vessels or the heart in order to keep the blood pressure at a normal level. Autonomic neuropathies (disease of the peripheral nervous system) cause mainly orthostatic dysregulations.Especially in the asympathetic form, the diastolic blood pressure and occasionally the heart rate is lowered. In addition, low diastolic blood pressure can also be induced by medication, for example in the treatment of isolated systolic hypertension. This is a form of hypertension in which the systolic value alone is too high.
