What Is Microvascular Ischaemic Disease?

Ischaemic microvascular disease is a condition where the small vessels in the affected area, usually the brain or the heart, are blocked or damaged, resulting in reduced blood flow. When this condition affects the brain, it can impact a plethora of body functions, including balance, cognition, walking, memory and urinary function. In the brain, this condition is the leading cause of vascular dementia, the second most common type of dementia after Alzheimer’s disease. In this article, we will go through the common risk factors, symptoms and treatments of ischaemic microvascular disease.

Definition of ischaemic microvascular disease (IMD)

Let’s break down the name ischaemic microvascular disease (IMD). Ischaemic is a term used to describe a reduced or blocked blood flow that causes a build-up of debris and reduced oxygen levels in the affected areas. The next term, microvascular, can be split into “micro” which means small and “vascular” referring to the blood vessels. So microvascular is the small vessels.

So, the ischaemic microvascular disease is the damage of organs due to reduced blood flow through our small blood vessels. Most of the time, IMD is most commonly associated with the brain.

IMD is also commonly referred to as:

• Cerebral small vessel disease (CSVD)
• Small vessel ischaemic disease or small vessel disease

IMD is reportedly the most common cause of vascular dementia.

IMD has a large impact on your overall health. This disease most commonly occurs in people who are mid to late age of life. It is important to regularly monitor your health, as IMD often arises from external risk factors and previous medical conditions.¹ Early recognition of risk factors and diagnosis of IMD is crucial to minimalise the effect of IMD on your overall health.

Causes and risk factors

There are many causes and risk factors associated with IMD. Some are medical conditions that make the microvascular system work harder or are more prone to reduced blood flow, while some are lifestyle choices.

Narrowing of microvessels due to atherosclerosis

Atherosclerosis is a condition where your blood vessels thicken or harden from a buildup of fat within them. From this, the vessels narrow, which increases the chances of heart attack and stroke. This can also contribute to the development of IMD.

Diabetes and its effect on microvascular function

Diabetes has a large effect on the microvascular function of multiple organs. Those with type-II diabetes have a higher risk for vascular diseases, including obesity, high blood pressure, and cerebrovascular diseases such as stroke. 

Hypertension and age: contribution to IMD

There are many risk factors associated with IMD, which can be divided into different parts of the body. Concerning vasculature, meaning your blood vessels and arteries, two major factors that contribute to the likelihood of developing IMD are advancing age and high blood pressure. High blood pressure, also referred to as hypertension, puts additional stressors onto your vasculature, while with increasing age, your blood vessels can become weaker.

Other risk factors: smoking, obesity, sedentary lifestyle, sleep

Like many diseases, there are many lifestyle choices you can make to reduce the likelihood or severity of the conditions. You have heard many times that you should eat healthily, get regular exercise, stop smoking and reduce your alcohol intake, but your lifestyle really does impact your health at significant levels. 

A healthy diet includes things such as eating proper amounts of vegetables, healthy fats, and proteins. The Mediterranean diet has been proven to be one of the healthiest diets, packed with fish, healthy fats, grains, vegetables, and fruits. You should also make sure your diet includes things such as folic acid and vitamin B12. Also, a diet where you consume high amounts of sodium can increase the risk of stroke, which is already a common feature in IMD, therefore potentially increasing the frequency or severity of these strokes.

Another risk factor is inadequate sleep. Disordered sleep at night has been associated with increasing stress in the brain. Think about when you did not get a good night’s rest or have pulled an all-nighter. You are more disorientated and unable to focus the next day. It has also been reported that sleeping throughout the day has been associated with enlarged perivascular spaces in MRI readings.¹

Common symptoms of IMD

Although IMD initially damages the brain, it also affects a multitude of other vital systems. This disease has effects on cognition, mood, urinary function, balance, neurological conditions, and the likelihood of strokes. If this disease is present in the heart, it can cause chest pain, shortness of breath, heart attack, or heart failure.²

Symptoms relating to impaired cognition include mild cognitive impairment such as difficulty remembering details, dementia, delirium, slow processing of information and impairment of attention and executive function.¹ 

IMD can cause lacunar strokes, where there is a blockage of blood supply to the brain, and haemorrhagic strokes, which involve excessive bleeding into the brain. These strokes are likely to reoccur and are associated with more severe stroke outcomes.

IMD can also affect your mood and personality. You could have feelings of depression, tiredness, and a lack of motivation to do things that used to interest you before.

It is important to have regular check-ups with your doctor and to let them know if you have a family history of IMD.

Diagnostic procedures

One of the most common methods to identify IMD is through magnetic resonance imaging (MRI). This is a procedure where a large magnet is used to produce an image of the brain or heart. From this image, your doctor will be able to identify any abnormalities of the brain that appear in either a difference of shape or white colours of the brain, which can be tiny scarring or damage of the tissue or cells. For the heart, your doctor can look at its function and structure.

Coronary angiography is where a cardiologist will direct a catheter into the blood vessels of the heart, and they will be able to measure certain parameters that will help the doctor understand how your heart is functioning. Sometimes, this is necessary as non-invasive techniques cannot measure the small vessels as accurately.

Treatment and management

Your doctor may recommend making lifestyle adjustments to reduce risk factors associated with IMD. This includes a low-sodium diet, cessation of smoking, and reduced alcohol intake. They may also recommend incorporating more exercise or getting regular sleep at night if you do not already do so. 

Medications to control risk factors

Your doctor may recommend treating the underlying cause of IMD. This can include medications to regulate blood pressure and cholesterol. Other medications can be for treating the underlying condition, such as diabetes or atherosclerosis (artery narrowing). 

Some medications that can be prescribed to improve the outcome of symptoms of IMD include:^1,3

• Antiplatelet medication - reduces the risk of strokes or heart attacks in some patients.
  • This type of medication is used to reduce the amount of clotting in your blood to prevent the blocks in your vessels that contribute to IMD symptoms.
• Nitric oxide and nitric oxide donor medication - this medication has been shown to improve cognitive outcomes after stroke. It is also used to manage ischaemic heart disease.¹
• Immunosuppressants - to prevent or slow the progression of IMD.
• Xanthine oxidase inhibitors - this category of medication is used for the prevention of gout.

It is important to consult your doctor on the best course of treatment as every patient can have different benefits from and reactions to different medications.

Summary

Ischaemic microvascular disease (IMD) is an overarching term used when there is damage to organs such as the brain or heart from reduced blood flow through the small blood vessels. IMD is commonly associated with the brain and can also be referred to as cerebral or ischaemic small vessel disease. When in the brain, IMD can affect cognition, memory, balance, the urinary tract, and neurological factors. From the damage to the small vessels, blood cannot flow at a normal rate. This reduced blood flow can lead to a build-up of waste and reduced oxygen to the surrounding tissues. As a result of this, there is an increased risk of recurring strokes or heart attacks with worse outcomes.

There are many risk factors associated with IMD. One unavoidable factor is old age, as this condition affects people mid to late in life. Other factors include medical conditions such as high blood pressure, diabetes and atherosclerosis, as well as lifestyle choices such as diet, tobacco intake and alcohol consumption. There are a number of methods to diagnose IMD. After taking a medical history, your doctor may use non-invasive techniques to look at the structure of the affected area, such as an MRI or ultrasound. In some cases, an invasive technique is needed, such as a coronary angiography. Treatment may include making lifestyle changes to improve the health of your microvascular system or taking medication that can treat the underlying cause or help improve the prognosis of the disease.