Hereditary Hemorrhagic Telangiectasia (HHT) > Fact Sheets > Yale Medicine

With every beat of your heart, blood courses through your cardiovascular (circulatory) system—a complex, canal-like network of strong, flexible tubes such as arteries, capillaries, and veins. 

When these vessels function normally, blood flows easily through them, transporting the entire body’s oxygen and nutrients while helping to maintain blood pressure and remove cellular waste. However, sometimes structural weaknesses or anomalies can present danger. This happens especially in people born with Hereditary Hemorrhagic Telangiectasia (HHT), a genetic disorder that affects the blood vessels.

Because this condition doesn’t cause any warning symptoms—and leaves people vulnerable to stroke and life-threatening infections—proper diagnosis, treatment, and monitoring is important.

People with this genetic condition have multiple malformed blood vessel connections that bypass capillaries, which normally connect arteries to veins. In the absence of capillaries, direct links between arteries and veins (called telangiectasia when small and arteriovenous malformations [AVM], when larger) occur. 

These can allow clots and bacteria that would normally be filtered out by the capillaries to get into the lung, where they can cause stroke and serious infections such as brain abscess. Also, AVMs and telangiectasia can be weak and prone to burst open and bleed. Depending on where these artery-vein connections are located in the body, this can be a life-threatening emergency. 

“Patients with suspected HHT, such was those with family members having this condition,” says Jeffrey Pollak, MD, interventional radiologist and medical director of the Yale Medicine HHT and Vascular Malformations Program, “should be screened for this condition and specific sites of involvement, especially since sudden life-altering events that might occur even in the absence of any preceding symptoms can potentially be prevented if HHT is known and treated in advance.”

At Yale Medicine’s HHT & Vascular Malformation Program, we are leaders in the diagnosis, treatment, and research of vascular malformations, whether they are caused by HHT or not. Our program’s multidisciplinary approach and principles of care have been adopted by HHT centers worldwide. 

We continue to develop care guidelines for the diagnosis, treatment, and follow up of pulmonary and cerebral AVMs. We’re also leading the way in developing guidelines for managing patients with heart failure and other complications of HHT liver vascular malformations.