11 June 2007

Atrial Fibrillation - cause and treatment

Atrial Fibrillation

What is it?

Atrial fibrillation (AF) is a condition in which the heart beats with an abnormal or irregular rhythm. When the heart beats rapidly and irregularly, serious problems can occur such as blood clotting. The abnormal rhythm can come and go (called paroxysmal atrial fibrillation), persist for longer than 7 days (persistent atrial fibrillation), or persist despite treatment (permanent atrial fibrillation).

Atrial Fibrillation

What causes it?

The heart muscle has four chambers or compartments. The two upper chambers are called the right and left atria. Within the right atria, is a small mass of tissue - known as the sinoatrial node (SA node). This SA node triggers an electrical - like impulse that stimulates the heart muscle to beat and pump blood in and out of the heart. The SA node is like a “pacemaker” for the heart. It controls how fast the heart beats and keeps the rhythm of the heart regular.

For most individuals, when the heart beats at a normal rate and rhythm, it pumps about 60 to 100 times per minute. Atrial Fibrillation (AF) can cause the heart to beat 120 to 180 times per minute, or faster. When AF occurs, electrical impulses originate from many areas in the atrium instead of from the SA node - as many as 350 different impulses per minute, all trying to cause the heart to beat. Unfortunately, the heart cannot respond to the overload of electrical - like impulses and thus it begins to beat rapidly and irregularly - almost like a quiver instead of a beat. The fast and irregular beating of the heart can cause the feeling of heart fluttering or palpitations. Additionally, blood is not pumped effectively and may pool in the atria. When blood pools, it is more likely to clot. If a clot develops and breaks loose it can clog a blood vessel in the brain, causing a stroke.

The two lower chambers - the right and left ventricles - of the heart are also affected by AF. Rapid and irregular beating does not allow sufficient time for the ventricles to adequately fill with blood before being stimulated to pump the blood out of the heart again. As a result, less blood is pumped out of the heart and the body’s tissues--which are dependent on the heart for oxygen-rich blood--are provided with a smaller supply, causing symptoms like shortness-of-breath, dizziness and fatigue or tiredness.


09 June 2007

Heart Failure Heart Disease

Heart Failure

What is it?

Heart failure, also called left ventricular dysfunction, is a condition in which the heart muscle does not pump adequately. As a result, blood is not dispersed adequately to the body and fluid backs up into the lungs, causing "congestion."

In some patients, heart failure occurs suddenly, while in other cases it develops gradually. As heart function deteriorates over the years, the strength of muscle contractions may be reduced. In other cases, mechanical problems may affect the ability of heart chambers to fill with blood, so that less blood is pumped out to tissues in the body. In other cases, the pumping chambers enlarge and fill with too much blood. The weakened heart muscle may not be strong enough to pump out all of the blood it receives. There are also cases where the heart enlargement affects the functioning of the valves that usually stop blood from flowing backwards into the heart chamber it just left. This condition, called regurgitation, may make the heart failure even worse.

When the heart cannot efficiently pump blood into the arteries, the blood backs up into the lungs and the resulting fluid collection is responsible for the congestion and breathing difficulties. Blood may also collect in veins, especially in the lower extremities, and cannot circulate into tissues.

In most patients, heart failure is controllable. With appropriate care, people may live for many years after the diagnosis is made.

What causes it?

Heart failure (HF) is often the direct result of the heart muscle's inability to contract with enough force to pump blood efficiently. Among the causes of HF are heart valve disease, scar tissue left from a previous heart attack, and high blood pressure which has been uncontrolled for long periods.

Coronary artery disease, in which the coronary arteries supplying the heart muscle are narrowed by plaques (usually from high cholesterol), is the most common cause of HF accounting for 60% of people with the disease. Although coronary artery disease often starts at an early age, HF occurs most often in the elderly. The majority of these patients are women. Researchers theorize that this is probably because men are more likely to die from coronary artery disease before it progresses to HF.

HF is also associated with alcohol abuse, and drug abuse, particularly cocaine and amphetamines, which affect heart rate. Among other disorders that can cause HF are hyperthyroidism -- or an overactive thyroid-- and various abnormalities of the heart valves. In addition, viral infection or inflammation of the heart, known as myocarditis, or a heart muscle disease called cardiomyopathy can cause HF. There are also rare cases where HF is caused by extreme vitamin deficiencies.

What are the risk factors?

Risk factors are characteristics that may increase your chance for developing a condition. If you have conditions such as coronary artery disease, valvular heart disease or high blood pressure, then you are at risk for developing heart failure (HF). Other factors that increase your chance of having or developing HF include:

  • Age - Older people are more likely to develop HF than younger people.
  • Male gender - Before age 60 or 70, men are more likely than women to develop coronary disease.
  • Family history of heart disease
  • Cigarette smoking
  • High blood pressure
  • Diabetes
  • Alcohol abuse
  • Coronary artery disease
  • Chronic kidney disease
  • Atrial fibrillation
  • High cholesterol
  • COPD (lung disease) or asthma