What are AVM's?


AVM, Arteriovenous Malformation is an abnormal connection between a artery and a vein. Avm can form anywhere in body where an artery contects to a vein but are most commonly seen in persons with hht in lungs, liver, intestinal tract and brain. 

Avm's can be congenital, we can be born with them and they are usually there by end of adolescence. They can be asymptomatic for long periods of time even a whole life time. They can however cause health problems, pain, discomfort, loss of blood, strokes, brain infections, brain abscess or even loss of life. 


In a normal human body, arteries carry blood away from the heart to lungs or rest of the body. The blood then passes through the capillaries, the veins then return the blood to the heart. If you have an avm this process is interrupted, the avm causes a direct contection between the artery and the vein.







Avm is missing the capillaries which has a calming effect on the blood flow, avm's can progressively get larger causing the heart to work harder to keep up with extra blood flow. The avm also causes surrounding areas to lack the function of the capillaries, delivery of oxgyen and nutrients and taking away waste products such as co2.


Pulmonary avm or lung avm affect about 50% of people with hht and more then half of pulmonary avm's seen by doctors are due to hht. When a pulmonary avm is present the avm bypasses the capillaries causing the blood not to pick up oxgyen and go straight back to the heart, normally giving a person a lower oxygen level. Treament for pulmonary avm's will be talked through with your consultant but normally is an Embolization.


Embolization is a procedure where a small needle is inserted through the skin into a vein, usually in the groin, a catheter is then placed into the femoral vein using imaging to guide them doctor close the blood flow to avm sometimes using coils, plugs or glue. Your consultant will talk through which option they are using. 


Cerebral avm or brain avm affects 5-20% of people with hht. There is number of different treatments for cerebral avm's and a consulant will talk through which treatment is right treatment for your cerebral avm. Some you may hear of are,

Embolization as above.

Surgery to remove avm.

Gamma Knife focused beams of radiation directed at the abnormal vessels of avm causing them to thicken ultimately shutting off blood suppile to avm.

Conservative medical management monitoring of avm with focus on symptom management. 


Liver avm's these are currently only treated if you are symptomic. Liver avm's are common in people with hht but only about 10% of those who have them require treament. Any treatment of liver avm's is personal to your case and a consultant will talk through options with you.


Intestinal avm's, about  20% of people with hht will be affected. The biggest problem with intestinal avm's is bleeding leading to anemia. Treaments can include hormone pills, tranexamic acid and laser treament.