Pulmonary Arterial Hypertension
Pulmonary arterial hypertension (PAH) is a rare and serious condition that affects the lungs and damages the right side of the heart. The severity of symptoms usually correlates with progression of the disease and, if the condition gets worse, it can be life-threatening. PAH can affect people of all ages, but it is more common in people who have additional heart or lung conditions.
Symptoms may include shortness of breath, tiredness, periods of feeling faint of dizzy, and others. Symptoms often get worse during exercise, which can limit patients’ ability to take part in and enjoy daily life. Left unchecked, PAH will cause right heart failure, which can be fatal. It is thus important to start treatment as soon as possible.
Doctors have grouped PAH according to its causes. No matter which group, all PAH patients have high pressure in their lungs. This is caused by thickening and hardening of the walls of blood vessels in the lungs (pulmonary arteries). Because pulmonary arteries become stiff and cannot expand as well, it becomes harder for blood to flow through the lungs. This makes it harder for the right side of the heart to pump blood through the lungs. If the right side of the heart must work harder, the extra effort eventually causes the heart to become weak and to fail (right heart failure).
There are detailed treatment guidelines doctors can follow, but there is no cure for some types of PAH. Treatment can, however, help reduce symptoms and improve patients’ quality of life. Available treatments for PAH may include anticoagulant medicines to reduce the blood’s ability to thicken (clot) and diuretics to remove excess fluid as a result of heart failure. Patients may also be offered medicine to widen the blood vessels. Home oxygen treatment may also be prescribed if the level of oxygen in the blood is low. Sometimes, however, PAH symptoms persist even though doctors and patients are doing their best to manage the condition and a heart-lung transplant may be the only alternative.
A technique known as interatrial shunting can improve symptoms. Interatrial shunting is a technique developed in the 1960s and the idea behind interatrial shunting is simple: make a tiny opening in the wall between the two atria of the heart (interatrial shunt) that acts like a pressure valve. Blood can now flow through the opening from the high- to the low-pressure side (decompression).
Interatrial shunting has been used in many patients with PAH and it is under investigation to see if the technique can improve symptoms and possibly outcomes in pulmonary arterial hypertension (PAH) patients.
The results are often immediate, and many patients experience reduced symptoms and feel better. But this only works if the interatrial shut remains open. Because of natural healing processes, the tiny hole will close again in most patients, unless an implant is used to keep it open. Making it larger from the start may not be safe and re-doing it is also not a good alternative.
The Atrial Flow Regulator (AFR)
The Atrial Flow Regulator (AFR) is a tiny device that can be used to keep the interatrial shunt open and control its size. The device has two disks with a central opening (fenestration or shunt) so that blood can flow through the AFR, from the right to the left side of the heart. The device is made from elastic metal wires (nitinol) that are braided and molded into the final shape of the AFR. Nitinol has been used safely for decades to make medical devices that have been implanted in hundreds of thousands of patients. The AFR is implanted using established and safe minimally invasive (transcatheter) techniques performed by specialized doctors (interventional cardiologist).