Congestive heart failure (CHF), or heart failure, occurs when a damaged heart is not able to pump enough blood to the body’s other organs for them to function properly.

Causes

Congestive heart failure is the end result of at least one other cardiovascular problem in the body, such as coronary artery disease (which accounts for 60 to 70 per cent of all cases of heart failure), where the arteries that supply blood to the heart muscle become narrowed or blocked, leading to heart attacks, which weaken the heart muscle. As well, scar tissue from past heart attacks can interfere with the heart muscle’s normal work. Other causes include:

• long-standing high blood pressurea faulty heart valve (often caused by rheumatic fever)

• an infection of the heart valves (endocarditis) and/or heart muscle (myocarditis)

• congenital heart defects (abnormalities in the heart present at birth)

• inflammation of the heart (often caused by viruses)

Diabetes and excessive alcohol and drug use can also lead to heart failure.

Effects

The causes of heart failure may be different, but they all have the same effect: they damage the heart muscle in some way, which reduces its ability to pump blood.

The “failing” heart keeps working, but not as efficiently as it should, and blood returning to the heart through the veins backs up. This causes congestion in the tissues and in the kidneys, which may lead to swelling (edema) throughout the body, most often the legs and ankles.

At time goes on, the heart tries to compensate by increasing in size and the heart muscle thickens (like any other muscle under strain), which causes the heart to grow even larger. But instead of strengthening the heart, this enlargement continues to weaken it by further reducing how efficiently it can pump blood. Eventually, the heart is unable to keep blood circulating properly throughout the body. Blood pressure begins to drop and fluid may build up in the lungs, causing shortness of breath, especially when lying down.

Symptoms

These symptoms may worsen if the person eats a high-salt diet, drinks an excessive amount of fluids, takes medications that cause water- or salt-retention, or comes down with a cold or the flu.

Treatment

There is no cure for heart failure, but it can be controlled by treating the underlying conditions that cause it. The goals for treatment are to:

• improve symptoms

• stop the heart failure from getting worse, and

• prolong life span

Treatment for people with mild or moderate heart failure usually includes lifestyle changes – such as more rest, a low-salt diet and modified daily activities – and medications. These medications might include ACE inhibitors and vasodilators to expand blood vessels and allow blood to flow more easily; beta blockers to improve how well the heart pumps blood; digitalis to increase the pumping of the heart; or diuretics to help the body eliminate excess salt and water.

Other treatment will depend upon the root cause of the heart failure and might include:

• Surgery to repair or replace a faulty heart valve:

  During the surgery, the patient’s heart is stopped and a machine takes over the work of the heart and lungs while the surgeons operate. Replacement valves are either mechanical (made from durable metals, carbon, ceramics or plastics), or biological (made from animal or human tissue).

  Doctors are also now using non-surgical techniques to repair or replace faulty heart valves in some patients. Instead of opening the chest to operate on the heart, doctors insert a long, flexible tube called a catheter into an artery (usually in the groin or arm) and thread it through the blood vessels into the heart. This procedure does not require stopping the heart or the use of a heart-lung machine.

  Patients must take blood thinners after a heart valve replacement to prevent blood clots.

• Coronary artery bypass surgery:

  In this surgery – performed on people with severe atherosclerosis to improve blood flow to the heart muscle, especially those who experience marked exercise limitations due to chest pain (angina) – doctors take a healthy piece of blood vessel (artery or vein) from the patient’s leg, arm, or chest to create a detour or bypass around a blocked portion of the coronary artery.

  As with heart valve surgery, the patient’s heart is stopped and a machine takes over the work of the heart and lungs while the surgeons operate.

• An implantable pacemaker:

  In this procedure, surgeons implant a device called a pacemaker to regulate the heart rate and rhythm in patients with arrhythmia (abnormal heart rates or rhythms). Electrodes inside the pacemaker transmit electrical signals to the heart muscle from a pulse generator. These electrical signals then cause the heart muscle to contract (pump).

  Most pacemakers are implanted under local anesthesia; they do not require open-heart surgery.

• A mechanical heart pump:

  In this procedure, surgeons place a mechanical heart pump inside the patient’s body to take over the heart’s pumping action and help maintain blood circulation. Some pumps require open-heart surgery; others – known as balloon pumps – can be inserted non-surgically, using a catheter.

  Heart pumps may be left in permanently, but are also often used to temporarily support patients who are awaiting a heart transplant.

  For cases where the heart is so damaged it cannot be repaired, a heart transplant may be the only option.

  A heart transplant is an open-heart surgery in which a severely diseased or damaged heart is replaced with a healthy heart from someone who recently died.

  Heart transplants have been successfully performed since 1967. Today, more than 85 per cent of heart recipients will live at least an additional year and more than 70 per cent will live five more years.

  However, donor hearts are in short supply and patients face a lengthy waiting list to receive a donor heart. In addition, to prevent the body from rejecting the transplanted heart, recipients must receive immunosuppressant therapy – powerful drugs to suppress their immune systems – for the rest of their lives, which leaves them susceptible to a range of other diseases.

Scientists continue to look for new ways to prevent and treat heart failure. Researchers are also looking at genetics in relation to heart failure treatments (for example, one study is investigating whether patients who have certain genetic markers may respond better to beta blockers than those who do not) and at new surgical approaches to treatment. These new approaches include surgically removing scar tissue caused by a heart attack to restore some of a damaged heart's pumping capacity, and implanting a mesh-like device (developed at the University of Chicago) that limits the progressive enlargement of the heart and supports the heart’s swollen pumping chambers.

Researchers are also working to develop equipment that will improve the health and comfort of patients waiting for a donor heart, and to develop a mechanical heart that could permanently replace a damaged heart, inside the body with no external tubes or cables, and permanently solve the shortage problem. Known as “total artificial hearts,” several have been successfully implanted in humans, but the procedure is still experimental and only available in a few research centres.

Stem cells are a new and very promising area for heart failure research.

Scientists believe that – because stem cells have the potential to grow into any one of the body’s more than 200 cell types – they may be able to use them to promote the growth of healthy heart tissue and blood vessels, and restore at least some of the lost heart function.

In one 2004 study of 20 patients with severe heart failure at the University of Pittsburgh School of Medicine, 10 patients had adult stem cells taken from the bone marrow in their hip bones. Researchers then isolated the particular stem cells that influence blood vessel and heart growth (CD34+ and CD45-), and – in a process that took about 10 minutes – injected the cells into the damaged areas of their hearts during heart bypass surgery. After six months, all the patients who had the stem cell procedure were able to pump more blood than the 10 patients who had bypass surgery alone. None of the patients experienced any serious side effects or complications.

Studies using bone marrow stem cells from donors (rather than the patients themselves) have also shown some promise for people who have recently had a heart attack. After six months, some of the treated patients showed improved heart and lung function – which means they may be able to avoid heart failure in the future. Because the stem cells came from unrelated donors, it also means that the cells can be produced in large quantities and administered immediately as heart attack patients arrive at the hospital to prevent heart muscle damage.

Human trials are also underway using embryonic stem cells. Because researchers currently believe that embryonic stem cells may be naturally less likely to be rejected, or could be more easily engineered to avoid immune rejection, they hold perhaps the most potential, especially for heart attack victims.

The results of the trials using stem cells are encouraging, and many researchers now believe that cellular therapy will likely revolutionize approaches to heart failure: instead of being palliative and simply trying to alleviate symptoms, scientists may be able to regenerate healthy heart muscle and repair damaged hearts.

First, however, researchers have to determine exactly how the stem cells work. The theory is that stem cells introduced into a heart damaged by heart attack or chronic illness could feasibly differentiate into heart muscle cells and cells that promote new vessel growth, thereby improving the heart’s ability to contract effectively and restoring blood supply to the heart itself. However, researchers are not sure yet whether the improvements experienced by the patients in the trials who received stem cells have come from the growth of new heart muscle cells, or whether the stem cells triggered existing cells to come out of hibernation.

Researchers studying the use of embryonic stem cells are also trying to determine why, in animals, most implanted stem cells re-enter the circulation or die rather than engraft to the heart muscle wall to form new muscle cells. They are also looking at ways to use gene therapy to increase the number of embryonic stem cells that live on as new muscle cells.

Stroke is a leading cause of adult disability in the developed world and even more so in the developing world. It afflicts 25 million people worldwide, and the number of new cases is rising seven percent a year as the population ages. In North America and Europe, stroke is the third most common cause of death after heart disease and cancer.

There are two types of stroke.  The vast majority are ischemic strokes and result from a blood clot or blocked artery.  The other kind of stroke is hemorrhagic stroke and results from a burst blood vessel. In both instances, people need immediate medical attention.  A brain scan will determine the kind of stroke and whether the patient is eligible for a clot-busting drug that can reverse the stroke damage.

Those who survive a stroke can suffer various degrees of disability depending on which part of the brain has been damaged. Stroke represents a huge burden on the health care system, and on families coping with the aftermath – often lost income, lost independence, caregiving responsibilities and the need for long term care.

Causes

A stroke is caused by an interruption of the blood supply to the brain specifically the loss of oxygen and glucose that are required for brain cells to survive. What goes wrong? Somewhere in the circulatory system there is either a blood clot or sufficient narrowing of the arteries to restrict the flow of blood.

The risk factors for stroke are well known - smoking, high blood pressure, obesity, high blood cholesterol, a sedentary life style, diabetes and stress. Indeed, a diet low in fat and sodium, controlled blood pressure, maintaining a healthy weight and regular exercise are very effective ways to prevent a stroke.

A stroke can happen at any age, but age increases the likelihood of stroke. More women than men die from stroke.

Symptoms and treatment

Stroke is a medical emergency. The symptoms of a stroke are not difficult to recognize, and with prompt treatment disability can often be avoided. The warning signs are sudden weakness, trouble speaking or sense of confusion, vision problems, an unusually severe headache, and dizziness or sudden loss of balance.

A small window of opportunity - a long road to recovery

Essentially a stroke is both an event in the central nervous system (the brain) and a condition occurring in the circulatory system - the channels through which blood flows - not unlike a heart attack which damages the heart. A blocked artery can affect many organs, but it has particular and devastating effects on the brain.

Death and disability is common because existing interventions for stroke must be administered within three hours to be effective, in other words, to keep brain cells from dying. Once that window closes, there are no other ways to avoid the neurological impact.

If the patient survives, the long road to recovery begins.

Depending upon which of the two hemispheres is affected, a stroke may impact all sorts of brain functions - the ability to remember, make decisions, speak, move your muscles, reason, do simple calculations, control bodily functions and emotions, understand directions, take in new information, read and write. One of the most common outcomes is weakness or paralysis on one side of the body. Because the damage is localized to particular areas of the brain, therapeutic strategies are also quite specific for recovering certain functions.

Stroke rehabilitation techniques have helped many people restore some functioning by teaching other areas of the brain to compensate for the lost neurons. But until now there has not been a way to replace the lost cells.

Research on the use of stem cells to treat CNS injury and disease is progressing rapidly, partly because the investigations from a range of diseases are all focusing on repairing the brain by replacing or restoring neurons. This includes neurodegenerative diseases, like ALS or Parkinson's disease, genetic disease such as Huntington's disease, as well as brain cancer, spinal cord injury and stroke.

The lack of blood flow to the brain, and the loss of oxygen and nutrients it transports, are what cause brain cells (neurons) to die in the course of a stroke. Because clot-busting drugs need to be administered immediately to be effective, by the time a diagnosis is made, it is often too late.

Stem cells may help doctors extend that window of opportunity to support dying brain cells and reverse the cascade of events that is triggered by stroke. Also, stem cells may be able to replace cells that are irreversibly damaged by stroke.

Healing from within - endogenous repair

Endogenous repair - or "in vivo stimulation" - mobilizes the organism to heal itself. Adult stem cells in the brain (a vestige of the embryonic stem cells that originally developed our brains in utero) may be able to restore neurons lost through stroke. Other stems cells in the body, such as bone marrow stem cells, may be prompted to come out of their hiding places to help the cause.

This approach relies on the ability of certain adult stem cells, in particular those found in the adult brain, to differentiate into the kinds of brain cells that are required. It is a question of "turning on" the stem cells and providing the necessary instructions to rewire the brain after a stroke.

Picking up the right signals - exogenous repair

Exogenous repair, on the other hand, relies on stem cells being created outside of the patient's body in vitro (in a laboratory dish) and transplanted into the patient. Beginning with embryonic or fetal stem cells, this process involves adding growth factors to the mix as they develop. The aim is to multiply and either partially or completely differentiate the cells to become the nerve cell that is needed. This is the point where they can be injected into the patient's brain and either finish their transformation into the type of brain cell that is lacking (in the case of the partially differentiated cells) or participate in repair directly (for the fully differentiated cells).

A UK company called ReNeuron has achieved UK approval to initiate early clinical trials in Glasgow, Scotland. They will treat patients using a therapeutic dose (about 20 millions cells) of genetically-modified human embryonic stem cells (derived from an aborted fetus).  They claim that these cells will not so much replace lost cells as “activate repair pathways” to stimulate new blood vessels and brain cells. This is, in effect, a blending of the two approaches – artificially stimulating the brain through cell transplantation to repair itself.

These studies suggest that stem cells may help in several different ways to treat stroke. What is clear is that we now know enough to begin to use stem cells to reverse the damage done by stroke, although it will be some time before these therapies are routinely available.

Our thanks go to the Stem Cell Network in Canada for their work on this information