Arteriovenous malformation

We all know that there are three types of blood vessels in our body, namely arteries, veins and capillaries. Arteries and veins mainly store blood in our body and play a great role in our breathing. If arteriovenous malformations occur in our body, many functions of our body will be affected, and our ability to prevent diseases will gradually decrease, giving diseases an opportunity to take advantage, so we should pay attention to this situation.

Arteriovenous malformations have many characteristics, so how should we correctly identify the occurrence of arteriovenous malformations? This is the best opportunity to demonstrate our medical knowledge. If we don’t know how to identify it, it will cause certain troubles in our treatment of the disease.

Although there are several different syndromes of arteriovenous malformation, they all involve abnormalities of small mucosal or submucosal blood vessels ranging in diameter from 1 mm to >30 mm.

The cause of gastrointestinal arteriovenous malformations is unknown. In many patients, they are often accompanied by the following conditions, including severe valvular heart disease, chronic renal failure, gastrointestinal radiation therapy, chronic liver disease, collagen vascular disease and hereditary hemorrhagic telangiectasia [Rendu-Osler-Weber (ROW) syndrome.

Symptoms, Signs, and Diagnosis

Once gastrointestinal bleeding occurs due to arteriovenous malformation, recurrent gastrointestinal bleeding, chronic anemia or severe acute gastrointestinal bleeding will often occur during the course of the patient's disease. Common sites of arteriovenous malformations are the stomach, duodenum, proximal small intestine or right colon. The bleeding site of radiation telangiectasia depends on the location of the previously irradiated area.

Common upper gastrointestinal arteriovenous malformations

⑴ ROW syndrome with telangiectasia of the stomach, duodenum, or proximal small intestine;

⑵ Upper gastrointestinal hemangioma without other manifestations of ROW syndrome;

⑶ Watermelon stomach is a vascular lesion of the gastric antrum stripes. These upper gastrointestinal lesions often manifest as vomiting blood or black stools.

Arteriovenous malformations of the lower gastrointestinal tract

⑴ Abnormal vascular development, often affecting the right colon;

⑵Radiation telangiectasia, often located in the rectosigmoid region, because radiotherapy is often used to treat pelvic malignancies;

⑶Colic ROW telangiectasia is a rare cause of bleeding.

The most commonly used diagnostic methods for arteriovenous malformation bleeding are upper gastrointestinal endoscopy, colonoscopy, small enteroscopy, intraoperative endoscopy or visceral angiography (depending on the bleeding site). Usually, selective angiography or simple laparotomy often cannot find arteriovenous malformations. Whether it is obvious under endoscopy often depends on the microcirculation of the gastrointestinal mucosa, which is often affected by factors such as hypovolemia, anesthesia and reduced cardiac output. Technetium-labeled red blood cell scanning is less sensitive and has a lower diagnostic value.

Angiodysplasia is an acquired submucosal arteriovenous malformation seen in elderly patients that can cause lower gastrointestinal bleeding. Typical angiodysplasia lesions are usually 0.5-1.0 cm, bright red, flat or slightly raised, and covered with a thin layer of epithelium. Most patients have 2-3 lesions, and 70%-90% of the lesions are located in the right colon.

Patients are usually over 60 years old, with bloody or purple stools, long-term recurrent painless gastrointestinal bleeding, and no special abnormalities found in multiple examinations (including laparotomy). Bleeding may be acute or massive, without hypotension. Although endoscopy or mesenteric angiography may have false positives, it is the best diagnostic method.

Through the detailed introduction in the article, I believe everyone should have some understanding of the characteristics of arteriovenous malformations. It mainly occurs in middle-aged and elderly people because their body resistance is relatively weak and they lack exercise, which gives the disease an opportunity to take advantage. In order for us to better stay away from the troubles of diseases, we hope that everyone will exercise more and develop good living habits.