A strange condition where blood vessels inside the body become entangled: Let's simply learn about Arteriovenous Fistula!

Have you ever heard of this medical condition called Arteriovenous Fistula ? Perhaps you have heard this name because a friend of yours is undergoing kidney dialysis. Or perhaps you have noticed a vein somewhere on your body that is swollen and feels strangely pulsating when you touch it. This is the specific condition we are going to talk about today. Don't worry, we will talk about this simply, in Sinhala that you can understand.

What is this arteriovenous fistula?

Simply put, an arteriovenous fistula is a direct connection between an artery (a vein that carries blood away from the heart) and a vein (a vein that carries blood back to the heart). It's like connecting two water pipes together. This can happen anywhere in the body, especially inside our organs (e.g., brain, kidneys) and in our limbs.

Think of it this way: the blood circulation in our body is like a system of roads.

• Arteries: These are like big highways. They carry clean blood (full of oxygen) from the heart to the rest of the body. The blood pressure is high here.
• Veins: These are the blood vessels that carry deoxygenated blood (high in carbon dioxide) back to the heart from various parts of the body. The blood pressure in these vessels is lower than in the arteries.
• Capillaries: These are very fine, small, narrow pathways (bypasses). Blood from the arteries passes through these capillaries, providing nourishment to every cell in the body, and then returns to the veins.

Normally, blood from arteries doesn't go directly to veins. It first goes through a network of very small blood vessels called capillaries. However, when a fistula forms, blood bypasses this capillary system and jumps directly from the artery into the vein.

This can cause several problems:

• The veins cannot withstand the high blood pressure in the arteries, so they begin to bulge and swell.
• Blood circulation becomes disrupted. Some areas may not receive enough blood.
• If this fistula is large, the heart has to work harder to pump blood. Over time, this can cause the heart to weaken, a condition we call ``Heart Failure.''

Sometimes these fistulas are created intentionally by doctors, especially for kidney patients who need dialysis. Then it is beneficial. However, some fistulas may be harmless, but some can cause serious health problems.

Who can develop this condition? How common is it?

These fistulas can develop at any age and in anyone. They are especially likely to develop after an injury. Some types of fistulas are more common in certain groups.

Actually, this condition called fistula is very common. But not all types are like that.

• Most common: Fistulas created by doctors to treat kidney patients with dialysis.
• Least common: fistulas that are present at birth (we call them `(Congenital fistulas)`).

What are the symptoms of a fistula?

Symptoms can vary depending on where it is located. Some people may not have any symptoms at all. However, the most common symptoms are:

• Swelling: There may be swelling around the fistula. This is especially noticeable in fistulas that are under the skin. For example, one area of ​​an arm or leg may be more swollen than the others.
• Skin discoloration: The skin in that area may turn purple or dark red.
• Varicose veins: The veins may appear enlarged and twisted.
• Feeling warm: When you touch the area where the fistula is, it may feel warmer than other areas.

Symptoms of reduced blood flow (`(Ischemia)` or `(Steal Syndrome)`)

Sometimes, if the fistula in an arm or leg is very large, blood flow to parts of the body that are further away from the fistula (e.g., the fingers) can be reduced. This is called ischemia . It is as if the fistula is "stealing" the blood that should be going to those parts, which is why some people call it "Steal Syndrome."

At times like this, symptoms like these may occur:

• Numbness and tingling sensation.
• Muscle twitching or pain.
• Skin wounds (ulcers) that take a long time to heal or don't heal at all.

Symptoms of Heart Failure

A large fistula can also cause problems for the heart. Because the blood doesn't flow properly around the fistula, the heart has to work harder to pump blood properly. Over time, this can weaken the heart and lead to heart failure . Symptoms such as:

• Difficulty breathing (Dyspnea).
• Tiredness, fatigue.
• Swelling of the legs and feet (Edema).

Congenital Arteriovenous Fistulas (`(Congenital Arteriovenous Fistulas)`)

Since these are formed while the fetus is still in the womb, the symptoms may vary slightly. These can cause changes in the development of the affected body part.

• If it is placed on an arm or leg, that arm/leg may be filled with more muscle than the other side, and the bones may become longer.
• Some people may experience swollen fingertips, soft nails, a bulge in the middle, and a downward curve at the tip (this is called clubbing ).
• Sometimes, the blood flow to the affected arm/leg is reduced, and the area may turn blue.

What causes this fistula to form?

There are three main reasons:

1. Injuries: The main cause of unexpected fistula formation is injury. For example, if both an artery and a vein are damaged, whether from a serious accident or a knife cut, they can stick together and form a connection like this as they heal. Sometimes this is only discovered years after the injury.

2. Congenital: These are conditions that occur while the baby is still developing in the womb. Most of the time, these are multiple small fistulas instead of one large fistula. However, if this occurs in a very important area (like the brain), it can be fatal.

3. Dialysis: In order to perform dialysis on patients with kidney failure, doctors perform surgery and intentionally create a fistula. This allows the needles that connect to the dialysis machine to fit properly and blood to flow properly. In fact, fistulas are most commonly seen for this reason.

Very rarely, a fistula can also form due to diseases such as cancer, certain infections, or an aneurysm, a condition in which the wall of an artery weakens and bulges like a balloon, causing pressure on a nearby vein.

Important: Fistula is not a contagious disease. This means that you cannot catch it from someone else, nor can you spread it to someone else.

How do doctors diagnose this? (Diagnosis)

Your doctor has several ways to diagnose this condition. They usually do a physical exam and some special imaging tests.

Here are some things to do during a physical examination:

• Examination: The doctor will look at the area of ​​your body where they think there is a problem, or at other areas that are related to it. They will look for swelling, discoloration, or bulging veins.
• Listening: A stethoscope is used to listen to the suspected fistula. This is because blood flowing through a fistula makes an unusual sound. It can sound like a machine working, because the blood is flowing in both directions, not just one way.
• Palpation: You can feel the pulsation as blood flows through the fistula, which can be felt by placing your hand on it. The doctor can also gently press on the area. If the heart rate slows down slightly when doing so, that is also a sign of a fistula.

What tests are done to diagnose this condition?

You will likely have one or more of these tests:

• Duplex Ultrasound: This uses high-frequency sound waves to look inside the body. This is similar to how a bat uses sound to find things in the dark. This can help determine the location of the fistula and its size.
• Angiogram: In this test, a special liquid (we call it a contrast dye) is injected into the blood vessels, and either an X-ray or a CT scan is taken. This liquid makes the blood vessels very clear, making it easier to find any blockages in the blood flow.
• MRI (Magnetic Resonance Imaging): This uses a strong magnetic field and computer technology to take very clear pictures of the inside of the body. It can also check for abnormalities such as fistulas.

What are the treatments for this? Can it be cured?

Most fistulas can be cured. It depends on the cause of the fistula, its size, and its location. Although congenital fistulas are difficult to completely cure, they can usually be treated and the problems they cause can be controlled.

Some people may not need treatment at first even if they have a fistula. Treatment is needed in the following cases:

• Hemorrhage: If the fistula is bleeding, especially if it is severe and cannot be stopped, it must be repaired.
• Enlargement: If the fistula or the blood vessels connected to it get bigger or change shape, it can cause problems for the surrounding tissues.
• Obstruction of blood flow: If a fistula blocks blood flow to a part of the body or if blood stagnates in one place, it can cause serious problems.
• Changes in appearance: Some people may experience emotional discomfort due to swelling and bulging veins caused by a fistula. In most cases, this appearance can be restored once the fistula is repaired.

What kind of medication or treatment is used?

The most commonly used treatments are:

• Catheter-based methods: In this, a long tube-like device (a catheter) is inserted into one of your large blood vessels (usually in the groin) and guided to the site of the fistula. Then, the fistula is created inside it. This can be done by inserting small devices such as coils or stents to close the fistula. Or, a special type of glue called cyanoacrylate glue can be used to close the hole.
• Surgery: Sometimes, if the fistula cannot be reached through the blood vessel, or if the fistula is very large, a surgeon can make a direct cut to repair the fistula. This can involve separating the artery and vein, or taking a piece of blood vessel from another part of the body and grafting it into the damaged area.
• Radiation therapy: In some cases, this method is used to destroy the connection between the fistula and the blood. Radiation is aimed directly at the fistula, causing it to scar. This prevents blood from flowing through it.

Medications are also used to treat fistulas. If a fistula is at risk of blood clots, blood thinners are given. These medications prevent blood clots from forming in the blood vessels, and prevent a clot from breaking loose and getting stuck in places like the heart, brain, or lungs, causing fatal conditions like heart attack, stroke, or pulmonary embolism .

Fistula for dialysis:

These are usually not treated unless they become a problem. If a problem does arise, surgery is often the only option.

The potential complications or side effects of treatment vary depending on the treatment, the size of the fistula, and its location. Your doctor can explain this to you in more detail.

How do I take care of myself/manage symptoms?

You cannot diagnose this fistula condition on your own. Because some of its symptoms can be similar to those of other serious conditions, such as aneurysms or blood clots. Therefore, never self-diagnose and treat yourself. If your doctor tells you that you have this condition, he/she will advise you on how to take care of it.

How quickly you will recover after treatment, and how long it will take to heal, will vary depending on the treatment and the nature of the fistula. Your doctor will also tell you about this.

Can this situation be reduced or completely prevented?

In fact, it is difficult to prevent the formation of these fistulas. Because the most common causes are injuries (which are not intentional) and congenital. Fistulas created for ``(Dialysis)`` are intentionally created as an aid to your treatment.

What would happen if I had this situation? (Future vision)

Your outcome will depend on the size, location, and cause of the fistula. Small fistulas, or fistulas that are in only a few places, may not require treatment. Many people may have only mild symptoms or no symptoms at all.

However, larger fistulas, or fistulas in vital areas (such as the brain or heart), are the most likely to cause problems. Your doctor is the best person to talk to you about this.

• Congenital fistulas: If these are not in a dangerous location, they usually have a good prognosis. However, if they are in a severe location and become large, they can cause serious complications, and even death.
• Fistulas made for dialysis: These usually don't cause problems. If side effects occur, your doctor can treat them.

How long can a fistula last?

A minor fistula can be present throughout life, with or without any problems. However, if the fistula is severe, it is important to see a doctor as soon as possible. This is because a large fistula can put pressure on the heart and cause heart failure . Although there are cases where the heart returns to normal after the fistula is repaired, this does not always happen. Therefore, the sooner the treatment is given, the better.

What should I be concerned about? When should I see a doctor?

If you have a fistula with few or no symptoms, the best thing you can do is to keep an eye out for any changes.

If you have a symptomatic fistula, your doctor will give you advice on how to care for it and what to watch out for. Some people may be told to wear special compression garments. These help reduce fluid buildup in the area.

See a doctor if you experience these symptoms:

• New pain or worsening of existing pain.
• Increased swelling at the site of the fistula, a new lump-like appearance (if you don't know you have a fistula, a new swelling/lump that appears for no reason).
• A change in color in a part of the body that is farther away from the fistula (for example, if the fistula is in the hand, in the fingers).

If you have a fistula created for `(Dialysis)`:

If someone with this type of fistula notices any of the following changes in the area, they should tell their doctor immediately:

• Signs of infection: swelling, redness, and warmth to the touch.
• A change in the speed of blood flow through the fistula during dialysis.
• An unusual bulge or change in shape.

When should you go to an Emergency Treatment Unit (ETU) ?

If you experience symptoms that suggest internal bleeding, or if you notice that blood is not flowing properly to a part of your body (especially an arm or leg), go to a hospital immediately.

Such characteristics are:

• Skin discoloration (near the fistula or all over the body).
• Dizziness, lightheadedness.
• Rapid heartbeat or breathing.
• Difficulty breathing.
• Sudden onset of severe pain near the fistula.

Your doctor can tell you about other symptoms that may require emergency treatment, depending on your condition.

Finally (Take-Home Message)

Arteriovenous fistula is a condition that can sometimes have no impact on your life, but sometimes it can cause major problems. It is very common for people with kidney disease to have a fistula surgically created for dialysis, and it is beneficial for them. However, rarely, serious complications can occur due to this. The good news is that with today's advanced medical science, this condition can often be treated, and sometimes even cured. Therefore, if you have any doubts or questions about this, do not hesitate to see a doctor and talk to them.

` Arteriovenous Fistula, Arteriovenous Knot, Venous Tangle, Dialysis Fistula, Heart Disease, Blood Vessels, Surgery