Microvascular disease (MVD) is a condition impacting the body’s smallest blood vessels, the microcirculation. MVD affects the networks of arterioles, capillaries, and venules responsible for delivering oxygen and nutrients directly to the tissues. Because it is a systemic problem, MVD can manifest with a variety of physical indicators that often do not fit the classic profile of heart disease. Understanding the specific signs and symptoms of this condition is the first step toward receiving appropriate care.
Understanding Microvascular Disease
Microvascular disease is defined by structural or functional damage to the smallest blood vessels, typically less than 100 microns in diameter. This damage impairs the vessels’ ability to properly dilate or constrict, which regulates blood flow to the surrounding tissue. When these vessels cannot function correctly, the result is localized ischemia, a restriction of blood supply that starves the tissue of oxygen.
MVD is fundamentally different from macrovascular disease, which involves the hardening and blockage of the body’s largest arteries. In macrovascular disease, symptoms arise from obstructions visible on standard imaging. Conversely, MVD involves widespread damage to the ultra-small vessels, meaning the main arteries often look clear even when the patient is experiencing severe symptoms. This distinction is why MVD is often referred to as small vessel disease.
Primary Cardiac Symptoms
The most common presentation of microvascular disease is Coronary Microvascular Dysfunction (CMD), which affects the heart’s small vessels. CMD is characterized by angina, or chest discomfort, that is often atypical compared to the classic “crushing” chest pain of a major heart attack. The discomfort may be described as a burning, squeezing, or tightness that can last for a prolonged period, sometimes exceeding ten minutes.
The pain may not be confined to the chest and can radiate to the back, neck, jaw, or shoulder, a presentation particularly common in women. Symptoms can be triggered by emotional stress or occur spontaneously while resting, unlike large artery blockages which typically occur during heavy physical exertion. Some individuals report a sensation of their clothing feeling too tight around the chest or discomfort similar to severe indigestion.
CMD also presents with non-pain symptoms that signal the heart muscle is not receiving enough blood flow. Shortness of breath (dyspnea) is a frequent complaint, often noticeable during routine daily activities like walking up a short flight of stairs. Pervasive fatigue is also commonly reported, often disproportionate to the patient’s activity level.
Sleep disturbances, including difficulty falling asleep or waking up feeling unrested, are linked to MVD. These non-specific complaints, combined with the atypical chest pain, contribute to the challenges in correctly identifying the underlying heart condition. The combination of atypical angina, dyspnea, and fatigue suggests a microvascular issue rather than a large artery obstruction.
Systemic Manifestations in Other Organs
Microvascular disease is a systemic issue, meaning damage is not limited to the heart but affects microcirculation throughout the body. The brain, kidneys, and eyes are particularly vulnerable because they are highly metabolic organs that rely on a dense network of tiny vessels. When MVD affects the brain, it is known as Cerebral Small Vessel Disease.
Cerebral small vessel disease can cause cognitive changes, including difficulty concentrating, problems with executive function, and subtle memory loss. It is a major cause of “silent strokes,” which are small, asymptomatic areas of damage that accumulate over time and can increase the risk of vascular dementia. More severe manifestations can lead to lacunar infarcts, which are small strokes resulting in symptoms like sudden numbness or weakness on one side of the body.
In the kidneys, microvascular damage is known as diabetic nephropathy, a progressive injury to the filtering units. Early signs include generalized malaise and changes in urination frequency, as the kidneys struggle to maintain proper fluid balance. As the condition advances, patients may develop swelling in the legs and ankles, a sign of fluid retention due to impaired renal function.
The eyes are also susceptible to microvascular damage, leading to a condition called retinopathy. This damage can be observed as microaneurysms, which are tiny bulges in the vessel walls, or areas of focal narrowing. Patients may experience blurred vision or other visual disturbances as the fine vasculature of the retina becomes compromised, restricting oxygen supply to the light-sensitive tissue.
Why Diagnosis is Often Missed
Microvascular disease is frequently overlooked because its symptoms do not align with the established diagnostic criteria for traditional heart or vessel problems. The atypical nature of the symptoms, particularly the non-classic chest pain and fatigue, often leads to misattribution. Clinicians may mistakenly diagnose these complaints as anxiety, stress, or other non-cardiac conditions, especially in younger patients or women.
A major barrier to correct diagnosis is the limitation of standard cardiac testing, such as traditional coronary angiography. This common procedure is designed to visualize the large coronary arteries and will appear normal if the patient’s symptoms are caused by microvascular issues. Since the microcirculation is too small for these tests to capture, the functional impairment is missed, and the patient may be told their heart is fine.
The population affected by MVD also contributes to the diagnostic challenge, as it disproportionately affects women and individuals with diabetes. Female patients often present with symptoms that are less classic than those seen in men, leading to a higher rate of misdiagnosis or delayed care. Specialized tests, such as positron emission tomography (PET) scans or cardiac magnetic resonance imaging (MRI), are necessary to measure blood flow reserve and detect dysfunction in the small vessels.