Heart failure
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of heart failure.
Alternative Names
Cardiomyopathy; Congestive heart failure
Surgery and Devices
Revascularization Surgery
Revascularization surgery helps to restore blood flow to the heart. It can treat blocked arteries in patients with coronary artery disease and may help selected patients with heart failure. Surgery types include coronary artery bypass graft (CABG) and percutaneous coronary intervention (PCI). CABG is a traditional type of open heart surgery. PCI, also called angioplasty, uses a catheter to inflate a balloon inside the artery. A metal stent may also be inserted during a PCI procedure. [For more information, see
In-Depth Report
#03:
Coronary artery disease.]
A 2006 study suggested that early treatment with revascularization surgery may be particularly important for patients with systolic heart failure, a condition that occurs when the heart does not pump out enough blood. This condition has a very high death rate. Researchers found that CABG or PCI surgery halved the risk of dying compared to standard drug therapy. Patients in the study first underwent a positron emission tomography (PET) test to determine if they would be good candidates for surgery.
Mitral Valve Surgery
In appropriate patients, mitral valve surgery may significantly reduce the severity of heart failure. In a study of 92 patients with late-stage heart failure and faulty valves, reconstruction of the heart's mitral valve drastically improved heart function.
An experimental mesh "heart sock" is being investigated as an adjunct to mitral valve repair surgery. Research presented at the 2004 American Heart Association Scientific Sessions suggested that the device reduced the progression of heart failure and halved the need for transplant surgery. The "sock" helps realign the shape of the heart and improve heart function. To date, it has been tested in patients with dilated cardiomyopathy.
Ventricular Remodeling and Restoration
Ventricular Remodeling.
Ventricular remodeling (also called partial left ventriculectomy or the Batista procedure, after its inventor) may allow some patients with dilated cardiomyopathy to avoid a heart transplant.
The procedure involves the following:
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The surgeon first performs ventriculectomy, which is the removal of a section of healthy heart muscle weighing about three ounces.
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The surgeon then reshapes the heart to a more normal size and form.
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Any faulty heart valves are repaired.
Ventricular remodeling is still relatively new, and mortality rates are very high. Studies on long-term improvement are mixed to date. More research is needed to target the patients who would most benefit.
Surgical Anterior Ventricular Endocardial Restoration (SAVER).
A related operation called surgical anterior ventricular endocardial restoration (SAVER), or the Dor procedure (after its inventor), combines elements of ventricular remodeling and coronary bypass surgery. It may be beneficial for those whose heart muscle has been scarred by a heart attack. An early study found that 85% of patients who had the surgery did not need to return to the hospital during an 18-month follow-up period. Additional trials are under way.
Dynamic Cardiomyoplasty
Dynamic cardiomyoplasty is an investigative treatment that has been useful in carefully selected patients with heart failure, although long-term and larger studies are still needed:
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The procedure detaches one end of a muscle from the back and wraps it around the ventricles of the heart.
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After a few weeks, these relocated muscles are conditioned with a pacemaker to behave and beat as if they were heart muscles.
Initial tests indicated that the procedure benefited the failing heart in many ways, including improving systolic pressure, limiting dilation of the heart, reducing heart muscle stress, and possibly reversing unwanted cardiac remodeling. But there have been subsequent problems with heart rhythm disturbances and in conditioning the relocated muscles. One study was stopped because of no difference in survival rates in patients with or without this procedure. Additional experience indicated that it was the restraining effect of the muscle wrap on the weakened heart that may have provided key benefits. Surgeons are now investigating cardiac support devices that cradle the heart in a mesh-like support as a possible new surgical avenue.
Heart Transplantation
Patients who suffer from severe heart failure and whose symptoms do not improve with drug therapy or mechanical assistance may be candidates for heart transplantation. Some 3,700 people are awaiting a transplant, although only about 2,000 operations are performed each year. Not all transplant units accept Medicare patients.
Traditionally transplants are performed only on more robust patients and patients under 60. About 76% of transplant patients are male, and 85% are white. Studies now suggest that older and sicker patients may achieve the best benefits. In fact, a study of almost 900 patients found that transplantation increased survival only for the sickest of patients.
While the risks of this procedure are high, the 2-year survival rate is about 78%; after 5 years it ranges from 50% to over 70%. In general, the highest risk factors for death 3 or more years after a transplant operation are coronary artery disease and the adverse effects (infection and certain cancers) of immunosuppressive drugs used in the procedure. The rejection rates in older people appear to be similar to those of younger patients.
Devices to Control Heart Pumping
A growing array of heart devices and machines are changing the face of heart failure treatment. They have gained widespread acceptance for use as a bridge to transplant in patients who are on medications but still have severe symptoms and are awaiting a donor heart. Increasingly, though, doctors are exploring the possibility that such devices may be satisfactory treatments themselves, forestalling the need for a transplant altogether in some patients.
Ventricular Assist Devices (VADs).
Ventricular assist devices are machines that help improve pumping actions. Several models with slightly different features are in use or under investigation. Some include the following:
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Left ventricular assist device (LVAD) are used for patients whose heartbeat has slowed dangerously (a condition called bradycardia) to help take over the pumping action of the failing heart. Studies now suggest that in some people the use of an LVAD may allow some of the damaged heart muscle to heal, perhaps even helping some patients avoid heart transplants. Until recently, these machines required remaining in the hospital. Smaller battery-powered LVAD units, however, are allowing many patients to leave the hospital and are proving to be effective bridges to heart transplants in adults. The HeartMate, for example, a portable LVADs about the size of a portable CD player (2 in. by 4 in.), is implanted in the upper abdomen. The implanted device plugs into an external power base, which is employed when the patient is at rest to recharge the battery and provide continuous power.
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Fully implanted miniature artificial pumps that assist the heart (not replace it) are also being tested. The DeBakey ventricular assist device (VAD) for example, is a tiny heart pump that weighs less than four ounces. It has been approved in Europe. The Jarvik 2000 heart pump is also showing promise.
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The intra-aortic balloon pump (IABP) is helpful for maintaining heart function in people with left-side failure waiting for transplants and in those who develop a sudden and severe deterioration of heart function. The IABP is an implanted thin balloon that is usually inserted into the artery in the leg and threaded up to the aorta leading from the heart. Its pumping action is generated by inflating and deflating the balloon at certain rates. Usually, it is used only for short periods, but some studies indicate that patients may be able to use it safely for somewhat longer periods (an average duration of 23 days in one study).
There are risks involved with many of these devices, including bleeding, blood clots, and right-side heart failure. Infections are a particular hazard.
Devices to Control Heart Rhythm
Pacers (Pacemakers).
Pacers, or pacemakers, help regulate the heart’s beating action, especially when the heart beats too slowly. Biventricular pacers (BVPs) are a special type of pacemaker used for patients with heart failure. Because BVPs help the heart’s left and right chambers beat together, this treatment is called cardiac resynchronization therapy (CST). BVPs may particularly help heart failure patients who have left bundle branch block, a condition in which the electrical impulses in the heart do not follow their normal pattern. In general, BVPs are recommended for patients with moderate-to-severe heart failure. A small 2006 study suggested that a defibrillator may be better suited for patients with moderate heart failure, while indicating a BVP might be best for patients with severe heart failure.
Implantable Cardioverter-Defibrillators.
Devices called implantable cardioverter-defibrillators (ICDs), which are sometimes combined with pacemakers, work well for preventing arrhythmias (abnormal heart rhythms) in heart failure patients. Studies have also found them effective in preventing sudden death from severe rhythm disturbances in patients with weakened hearts from previous arrhythmias and in patients with genetic hypertrophic cardiomyopathy. Patients who have an ICD should avoid taking fish oil supplements. A 2005
Journal of the American Medical Association
study found that omega-3 fatty acid supplements may increase the risk of rapid heart beat (ventricular tachycardia) or irregular heart rhythm (ventricular fibrillation) in some of these patients.
ICDs have many benefits, and recent expert guidelines recommend that they be used in more patients with heart failure. However, in June 2005, certain ICD models and biventricular pacemaker-defibrillators were recalled by the manufacturer because of a circuitry flaw that prevents the devices from delivering therapeutic electrical shocks when needed. The problem may result in patient death. Although the FDA did not make any specific recommendations, the agency encourages patients who may have such a device to ask their doctor if they should have it removed or replaced.
Devices to Remove Fluids
Ultrafiltration devices are used in hospitals to pump excess water and salt from the body. Catheters are inserted into several of the patient’s veins. The catheters are connected to a blood filter device. Blood is withdrawn through one of the catheters and filtered in the device to remove excess fluid. The filtered blood is then returned to the patient through another catheter. A 2006 study reported that ultrafiltration devices may work better than diuretic drugs for patients with acute decompensated heart failure (ADHF). ADHF is heart failure that has rapidly deteriorated so that patients require immediate hospitalization.
Implantable Artificial Heart
Surgeons implanted the first self-contained, artificial heart, known as the AbioCor, in five Americans in 2001. The heart, powered by an external battery that transmits electrical pulses through the skin, is a yo-yo shaped device about the size of a grapefruit. Although it did extend survival somewhat during these initial tests, it is highly experimental and intended only for those with very severe heart damage who are not expected to live longer than 30 days.
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Review Date: 4/11/2006
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Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital
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