Screening for lung AVMs (PAVM) is dependent on the age of the individual, and to a lesser degree, their symptoms. Preferably, individuals with HHT will have had screening for PAVMs by the time of their early teens. If a pregnant woman has not had a recent evaluation for PAVM, it is imperative for her to do so as soon as pregnancy is recognized. In many cases, an HHT Treatment Center will be able to use tests performed by another facility unless the original tests are too old, the old test is not of high enough quality, or the old test was performed a little differently.
Contrast Echocardiogram (bubble echo): The recommended test of choice for PAVM screening in adults and also used in older children and adolescents. This test uses sound waves (ultrasound) to determine if injected saline bubbles can get through the lung circulation and be seen back in the heart, on the left side. This is called a shunt. It is a very sensitive test but not everyone with a “positive” or “abnormal” bubble echo test has a Pulmonary AVM large enough to re- quire treatment by embolization. To determine if treatment is necessary, a chest CT scan should be done if the bubble echo is more than minimally abnormal.
Chest X-ray: A standard X-ray of the lungs to look at the size of your heart and the condition of your lungs.
Shunt Test: During this test you breathe pure oxygen for 15 minutes with a nose clip on, and then a small sample of arterial blood is collected from an artery in your wrist. This is not a routine screening test but rather is used to assess a patient before and after treatment for PAVMs.s
CT Scan of the Lungs: This is like a 3-dimensional high-resolution X-ray of your lungs. If “X-ray dye” is used, an IV will need to be started.
Pulmonary Angiogram: A catheter is inserted through a large vein in either your leg or neck, and is passed up into the arteries of the lungs. This involves one or more injections of “X-ray dye” into the arteries to expose the AVM.
PAVMs larger than a certain size should be embolized to prevent complications like brain abscesses and strokes. For smaller PAVMs, antibiotics prior to most dental work and certain other non-sterile invasive procedures, like colonoscopy, are recommended.
Until PAVMs are excluded by testing, a person over the age of 10 with known or suspected HHT should take antibiotics before all dental cleanings, work and other medical procedures which have a risk of introducing bacteria into the bloodstream.
To screen for Brain AVMs an MRI with and without gadolinium dye is recommended. Since brain AVMs have been known to cause brain hemorrhage even in infants, a brain MRI early in life is recommended.
Other than in the brain and lungs, HHT can be screened as the symptoms warrant. With this in mind, a yearly evaluation by a physician familiar with the wide spectrum of symptoms associated with HHT is recommended, along with an annual check of ferritin levels, hematocrit, and hemoglobin. Without periodic check- ups with an HHT expert, HHT related medical problems are often missed, misdiagnosed or mismanaged which can lead to catastrophic events.