What is fibromuscular dysplasia?

Fibromuscular dysplasia (FMD) is a vascular (blood vessel-related) disease in which cells in the arteries develop abnormally, resulting in the shape of the artery narrowing and bulging in places, resembling a ‘string of beads’ as opposed to being a straight tube. It mostly affects people assigned female at birth (AFAB) aged between 20 and 60, but it can also affect children, people assigned male at birth (AMAB) and the elderly.

FMD has been observed in almost every artery in the body, but the most commonly affected arteries are the renal arteries (which supply blood to the kidneys) and the carotid arteries (which supply blood to the brain). FMD affecting the renal arteries most often manifests as hypertension (high blood pressure), while FMD affecting the carotid arteries can present as stroke. 

FMD has been considered a rare disease. However, many patients are entirely asymptomatic, suggesting that FMD may be more common than originally thought, occurring in as many as 4% of people AFAB.¹

Symptoms of fibromuscular dysplasia

The symptoms of FMD vary depending on the arteries affected:

Renal FMD

• Hypertension (high blood pressure)
• Tears in the inner walls of the artery (arterial dissection)
• Pain in the flanks (the sides of the back of the abdomen)
• Abdominal bruit (‘swishing’ sounds)

Craniocervical (head and neck) FMD

• Headache
• Tinnitus (ringing in the ears)
• Dizziness
• Cervical artery dissection
• Neck pain
• Stroke
• Carotid artery bruit

Mesenteric (abdominal) FMD

• Weight loss
• Fatigue
• Postprandial (following a meal) abdominal pain
• Epigastric bruit

Subclavian (upper limb) FMD

• Upper arm weakness
• Paresthesias (pins and needles)
• Claudication (muscle pain following activity, e.g. raising the arms)

Lower limb FMD

• Claudication (muscle pain following activity, e.g. walking)
• Cold legs
• Poor blood supply to the feet

Coronary (heart) FMD

• Chest pain
• Shortness of breath
• Acute coronary syndrome (caused by sudden, reduced blood flow to the heart)²

Diagnosis 

FMD is most often diagnosed using vascular imaging methods:

• One of these methods is a duplex ultrasound, which assesses how fast blood moves through the arteries. Turbulence, elevated velocity (speed) and resistance in blood flow can be indicative of FMD
• Another method of FMD diagnosis is computed tomography angiography (CTA). This involves a CT scan and an injection of a dye, which will produce images of the blood vessels²

Treatment

Treatment for FMD usually involves controlling the risk factors and managing symptoms, such as hypertension, with pharmacological treatments. There are many lifestyle-related risk factors which can be managed to try and control the progression of FMD.

Lifestyle factors affecting FMD progression

Diet and nutrition

There are many aspects of the diet which can affect vascular health and the progression of FMD. Having a healthy diet is associated with a significant reduction in cardiovascular diseases.

High-fat diet

• A diet with more than 35% of its total calorie intake from fat is considered a high-fat diet. A diet high in saturated fat is heavily associated with an increased risk of cardiovascular diseases such as FMD since fat is directly linked to dysfunction of the vascular endothelium, the inner layer of the arterial wall³
• According to the NHS, some foods which are high in saturated fat are:
  • Processed meat, e.g. sausages
  • Butter and lard
  • Cheese
  • Chocolate
  • Biscuits, cakes and pastries
• UK guidelines recommend that nobody should eat more than 30g of saturated fat per day. Limiting the intake of foods high in saturated fat can reduce the risk of cardiovascular diseases. Check nutrition labels on food packaging to help reduce the amount of fat in your diet. Food that is high in saturated fat contains more than 5g per 100g, while food that is low in saturated fat contains less than 1.5g per 100g. To be considered saturated fat-free, a product must contain 0.1g per 100g or less

High-sugar diet

• Overconsumption of foods containing added sugar is highly associated with cardiovascular disease.³ High intake of sugar promotes the formation of reactive oxygen species (ROS), which can damage arterial cells⁴
• According to the NHS, the following foods contain high amounts of added, or ‘free’ sugar:
  • Biscuits
  • Chocolate
  • Flavoured yoghurts
  • Breakfast cereals
  • Fizzy drinks
• UK guidelines recommend that adults shouldn’t have more than 30g of free sugars a day and that sugar shouldn’t make up more than 5% of calories from food and drink each day
• Some tips for reducing daily sugar intake:
  • Drinking water or no-added-sugar squash as opposed to fizzy drinks
  • Reduce the amount of sugar added to hot drinks, e.g. tea or switch to a sweetener instead
  • Choose unsweetened, whole-grain cereals rather than cereals covered in sugar or chocolate
  • Swap unhealthy snacks, e.g. chocolate, for low-calorie alternatives or fresh fruit
  • More tips can be found on the NHS website

High-salt diet

• A high intake of salt is notoriously associated with high blood pressure, a symptom of many types of FMD. Reduced salt intake has been shown to lower blood pressure and lower the risk of cardiovascular complications⁵
• Some foods which are high in salt:
  • Some meats, e.g. bacon, sausages
  • Cheese
  • Bread and pizza
  • Biscuits and pancakes
  • Sauces, e.g. soy sauce, tomato sauces
• The NHS recommends the following to reduce salt intake:
  • Season food with herbs and spices, black pepper, garlic or chilli instead of salt
  • Choose foods which are low in salt by checking the food labels on the packaging
  • Opt for healthier snacks, e.g. plain rice cakes, fruit and vegetables or unsalted nuts
  • Buy tinned vegetables or fish in water rather than brine

Physical activity

• Regular physical activity is just as effective as medication in the management of cardiovascular disease. Exercise can reduce blood pressure and the risk of stroke, which are two of the main complications associated with FMD⁶
• However, it is important to note that FMD patients are at high risk of vascular dissection, and strenuous exercise is not advised due to an increase in heart rate
• Exercises recommended for FMD patients are 30-40 minutes of moderate-intensity aerobic activity 5-7 days a week and weight training with a lower resistance and higher repetitions
• A proper breathing and lifting technique is also essential in resistance training⁷

Smoking

• Regular smoking is heavily associated with cardiovascular disease. One study found that out of 190 patients with FMD, 42.6% were smokers⁸
• Smoking also increases the risk of stroke and heart attacks. However, quitting smoking at the age of 40 or younger has been shown to reduce the risk of death by as much as 90%⁹

Practical tips for managing FMD through lifestyle

Developing a personal plan

• Creating a plan can help you stay on track with lifestyle changes, as you can monitor your progress. Be sure to set realistic and achievable goals to increase your chances of success

Building a support system

• Having people supporting you can be a great motivator, whether this is family and friends or an in-person or online support group. They can hold you accountable and make sure you stay on track to reach your goals

Summary

Fibromuscular dysplasia is a vascular disorder in which arterial wall cells don’t develop normally, causing the arteries to resemble a ‘string of beads’ structure. FMD is most common in people AFAB aged between 20-60 and can lead to complications such as hypertension and arterial dissection. Unhealthy lifestyle factors such as high-fat, high-sugar and high-salt diet, lack of physical activity and smoking can cause or worsen cardiovascular diseases such as FMD. Even too intense or excessive exercises could put the patient at risk of vascular dissection, so moderate-intensity aerobic and lower resistance and higher repetitions of weight training are advised. Changes to these lifestyle factors can reduce the risk of cardiovascular disorders or make them more manageable.