Heart failure occurs when the heart is not pumping efficiently enough to keep a person healthy. Under physical activity the effects (symptoms) of heart failure are even more pronounced. Most commonly, patients with heart failure will experience shortness of breath, among other symptoms.
Left-Sided Heart Failure & Ejection Fraction
Left-sided heart failure is divided into heart failure with reduced ejection fraction (HFrEF or systolic heart failure) and heart failure with preserved ejection fraction (HFpEF or diastolic heart failure). Both are caused by changes in the walls of the heart’s chambers (ventricles) causing them to become weak and stiff. The result is that the heart becomes less efficient at pumping blood.
No matter how forceful the heart pumps, it can never pump all the blood out of a ventricle. The term “ejection fraction” (EF) refers to the percentage of blood that is pumped out of a filled ventricle with each heartbeat.
Doctors can measure how efficient patients’ hearts are by working out the ejection fraction (EF). Most often, they will use imaging methods to measure how much blood pumps through the left ventricle. Generally, this is done using soundwaves to create an echocardiogram. Other methods can also be used (e.g., cardiac magnetic resonance imaging, MRI). All methods create an image doctors can use to calculate the EF. An EF between 50% and 70% is considered normal.
HFpEF & HFrEF
HFpEF occurs when the left ventricle of the heart does not relax normally between beats because the ventricle has become stiff. When the heart cannot fully relax, it cannot fill up with blood before the next beat. With HFpEF, or diastolic heart failure, the EF will be in the normal range. Approximately half of heart failure patients have HFpEF.
HFrEF occurs when the left ventricle of the heart does not entirely contract and it will not pump forcefully enough to move blood sufficiently throughout the body. This causes the pressure in the left heart and the size of left chambers to increase leading to worsening symptoms. Patients who have an EF of under 40% have HFrEF.
Of the two types of left-sided heart failure, HFrEF is the condition that is understood better. There has been rapid progress in the last decade to develop treatment options and doctors have established treatment guidelines. HFpEF is still not understood that well, several studies to establish new treatment options have failed, and doctors do not have the same guidelines for what may be the most effective treatment.
There are many medications available to treat HFpEF or HFrEF. In addition to medications, catheter based techniques (e.g. percutaneous coronary interventions [PCI] or stents), surgically implanted devices (e.g. implantable cardioverter defibrillators [ICDs], pacemakers [cardiac resynchronization therapy, CRT] or left ventricular assist devices [LVADs]), or surgery can also be used to improve heart functions. Sometimes, however, heart failure symptoms persist, even though doctors and patients are doing their best to manage the condition.
A new 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. More recently, doctors have also started to use the technique in heart failure patients, and it is under investigation to see if interatrial shunting can improve symptoms and possibly outcomes in heart failure patients.
The results are often immediate, and many patients experience reduced symptoms and feel better. But interatrial shunting only works if the shunt remains open. Because of natural healing processes, the tiny hole will close again in most patients. Making the hole larger from the start may not be safe and redoing it is also not an effective 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 left to the right 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).
Several clinical studies have shown that the AFR and other interatrial shunting devices developed in recent years can be safely implanted and improve symptoms in HFpEF and HFrEF patients.
Access to the AFR
The AFR is CE-marked for use in patients with HFpEF or HFrEF and is for sale in Europe and other international markets. The AFR is not approved for use in the United States. Clinical studies to assess the long-term effects of the AFR are ongoing.