Heart Failure and LVAD

About Heart Diseases and Mechanical Heart Pumps

A weak heart or heart failure often results in shortness of breath on exertion, fatigue and fluid retention in legs.  Years of living with blocked coronary arteries, high blood pressure, and an uncommon disease known as cardiomyopathy which affects the muscles of the heart can leave your heart too weak to pump blood to your body, resulting in heart failure. As symptoms worsen advanced heart failure develops.
Treatment for advanced heart failure patients involves many options.  In the earlier stages, many drugs are effective.  However in advanced heart failure often drug treatment becomes inadequate.  Other treatment includes special pacemakers to synchronise the heart rhythm and defibrillators that correct dangerous abnormal rhythms.
When one reaches the stage of advanced heart failure the symptom becomes intolerable, requiring frequent hospital admissions and the life expectancy becomes short. They become breathless even at rest, requiring oxygen, with collection of fluid in the lungs, abdomen, loss of appetite and inability to walk.  Some are candidates for heart transplantation, which can dramatically improve survival and quality of life.  Unfortunately donor hearts are not always available and may not be available in many parts of Asia.
Among the many advances in medical therapy in the last decade, mechanical heart assist devices have now become a reality.  These small electrical pumps are connected to your heart and circulation to restore normal blood flow throughout the body resulting in rapid recovery.  The improved circulation of blood will enable you to return to your daily life with minimal restrictions.  Most patients will return to their almost normal life style, hobbies such as playing golf and even back to their occupation.  The outlook for these patients is more encouraging than even before.

Heart Failure and the Left Ventricular Assist Device (LVAD)

Heart failure is a progressive condition in which the heart's muscle becomes weakened after injury and gradually loses its ability to pump enough blood to supply the body's needs. Many people don't even know they have it because its symptoms are often mistaken for signs of getting older. Heart failure usually does not develop overnight - it's a progressive disease that starts slowly and gets worse over time. Medical therapy can often control the symptoms and slow the progression of the disease.
But when the heart disease progresses to end-stage heart failure, patient will suffer from repeated hospitalisation, swelling of the body, breathlessness, inability to sleep in the night due to difficulty in breathing, as well as inability to walk and eat due to congestion of the liver and abdomen. Progressively, other organs in the body such as the liver and kidneys will also suffer due to the low blood pressure caused by the weak heart.
When a patient reaches this stage, the outlook is poor, with life survival limited to less than two years. In fact, it is worse than a patient having lung cancer.
At this stage, the only hope the patient has is to undergo heart transplantation.  But unfortunately, due to universal shortage of donors, heart transplantation is available only to a minority of patients who satisfy the strict selection criteria. Furthermore, heart transplantation is only available in a few countries in Asia and they are often restricted to their residents only.
Fortunately, mechanical heart assist devices have developed over the years and have become an option for patients suffering from end-stage heart failure. It can be offered to patients as a bridge to transplant, until such a time that they receive a suitable donor heart or as a long term solution for those who are not eligible to transplant, or where such a programme is not available.

What is LVAD?

The left ventricular assist device, or LVAD, is a type of mechanical heart. The device is placed inside a person's chest, where it helps the heart pump oxygen-rich blood throughout the body.
Unlike an artificial heart, the LVAD doesn't replace the heart. It just helps the heart perform its job. This can mean the difference between life and death for a person whose heart has reached terminal heart failure.
A permanent LVAD is currently being used in some terminally ill patients whose condition makes them ineligible for heart transplantation. This is also called destination therapy.

How Does an LVAD Work?

Like the heart, the LVAD is a blood pump. One end of the pump is connected to the left ventricle -- that's the chamber of the heart that pumps blood out of the lungs and into the body. The other end is connected to the aorta, the body's main artery. A cable passes from the device through the skin. The outside of the cable is covered with a special material to aid in healing and allow the skin to regrow. This cable is connected to a controller and batteries.
The pump and its connections are implanted during open-heart surgery. A computer controller, a battery pack, and a reserve battery pack remain outside the body. Some models allow a person to wear these external units on a belt or harness outside. The battery pack has to be recharged at night.
Currently, only the new generation HeartMate II heart assist device has the approval from United States Food and Drug Administration to be used as a bridge to heart transplantation as well as for long-term or destination therapy.

Figure: The Heartmate II is a type of LVAD. The blood pump is implanted inside of the body. The pump is connected to a controller and batteries which are located outside of the body.
The HeartMate II pump is a small pump that works like a jet engine.  It is implanted just under the heart with a connector drawing blood from the left ventricle (pumping chamber) of the heart and pumping it into the aorta, continuously via a conduit.  The pump revolves around 9,000 to 10,000 revolutions per minute.  Although the pump is small, it can pump six to ten litres of blood per minute, more than the average requirement of four to five litres for a healthy adult.  The pump is powered by a set of rechargeable batteries which are carried by the patient outside the body in a waist pouch or a pair of holsters.  A flexible cable connects the pump to the batteries which exits through the abdominal wall. The pump is designed to work continuously for many years, with very minimal wear and tear.
Following the implantation of a mechanical heart assist device, patients will usually recover rapidly and often can be discharged home within two weeks. This is due to the normal restoration of blood circulation.  Majority of these patients are able to return to their routine activities, pursue their hobbies and get back to work.
Risk of blood clot formation in the pump is minimised by prescribing blood thinners.  The operative risks are less than 10 percent in this group of patients.
Thus Heart Mate II left ventricular assist device offers a viable and alternative therapy to patients who suffer end-stage heart failure, with the aim of getting them back to the community to pursue normal activities and to prolong life. 

Who can have an LVAD?

The following are general indications for LVAD implantation:
Bridge to transplant: A patient’s medical condition can be stabilised while they wait for a donor heart.
Destination Therapy: Patients who are not eligible to receive a heart transplant may be supported on an LVAD indefinitely, or where heart transplantation is not available.
A thorough medical evaluation will be conducted to ensure that LVAD implantation is the best option for the patient. This will include blood tests and other diagnostic studies to evaluate how well the entire organ systems in the body are functioning.
In addition to medical criteria, there are also psychosocial criteria that must be met. LVAD therapy requires strict adherence to a medical regimen and careful monitoring. All patients must have adequate social support (i.e. friends or family) to ensure a successful outcome. Prior to undergoing LVAD implantation, patients are required to identify caregivers who can commit to providing adequate support while the patient recovers from implantation of the device. This includes attending teaching sessions with the LVAD coordinators and being with the patient at all times for the first few weeks after hospital discharge and ensuring adequate transportation to medical appointments.

What Are the Benefits of an LVAD?

An LVAD restores normal blood flow to a person whose heart has been weakened by heart disease. This relieves symptoms such as being constantly tired or short of breath. And sometimes, it allows the heart to recover its normal function by giving it a chance to rest.

What Are the Risks and Complications of an LVAD?

As with any surgery, there are risks associated with LVAD implantation. These include infection, internal bleeding and heart failure, any of which could lead to death. There may also be risks that are currently unforeseeable. Your physician will thoroughly review the potential risks and complications of LVAD implantation with you before you are asked to decide whether or not to undergo the procedure.