Congestive Heart Failure (cont.)

Congestive Heart Failure Causes

Congestive heart failure (CHF) is a syndrome, not a disease, that can be brought about by several causes. CHF is a weakening of the heart brought on by an underlying heart or blood vessel problem, often a combination of several different problems, including the following:

• Weakened heart muscle
  
  
• Damaged heart valves
  
  
• Blocked blood vessels supplying the heart muscle (coronary arteries), leading to a heart attack
  
  
• Toxic exposures, like alcohol or cocaine
  
  
• Infections
  
  
• High blood pressure that results in thickening of the heart muscle (left ventricular hypertrophy)
  
  
• Pericardial disease, such as pericardial effusion (a large collection of fluid around the heart in the space between the heart muscle and the thick layer of pericardium surrounding the heart) and/or a thickened pericardium, which does not allow the heart to fill properly
  
  
• Congenital heart diseases
  
  
• Prolonged, serious arrhythmias  

While these conditions often combine to produce CHF, sometimes the causes of diseased heart muscles are not known; this is called idiopathic cardiomyopathy or heart muscle disease of unknown cause.

CHF is often a result of the following lifestyle habits:

• Unhealthy habits, such as smoking and excessive use of alcohol, are often to blame.
  
  
• Obesity and lack of activity may contribute to CHF, either directly or indirectly through accompanying high blood pressure, diabetes, and coronary artery disease.
  
  
• Years of uncontrolled high blood pressure damages both heart and blood vessels.

Along with lifestyle risk factors, a number of diseases (for example, diabetes, heart attack [myocardial infarction], and congenital heart disease) can damage the heart and lead to congestive heart failure. Over a hundred other, less common, causes of CHF include a variety of infections, exposures, complications of other diseases, toxic effects, and genetic predisposition.

Whether through disease or lifestyle choices, the pumping action of the heart can be impaired by several mechanisms:

• Heart muscle damage (cardiomyopathy): The heart muscle can become weak because of damage or disease and thus does not contract or squeeze as forcefully as it should. This damage to the muscle can occur from coronary heart disease (coronary artery disease) leading to a heart attack, or long-standing high blood pressure, viral infection, alcohol abuse, diabetes, or many other less common causes. Sometimes, the cause is not known.
  
  
• Heart attack (myocardial infarction): A heart attack commonly causes severe pain in the chest, shortness of breath, nausea, sweating, and/or a feeling of impending doom. Heart attack may rapidly lead to either cardiac arrest (no heartbeat) or permanent damage of the left ventricle. If this damage is bad enough, that part of the heart will not work properly, which leads to heart failure.
  
  
• High blood pressure (hypertension): Abnormally high blood pressure increases the amount of work the left ventricle has to do to pump blood out into the circulatory system. Over time, this greater workload can damage and weaken the heart. This can lead to heart failure if this damage is allowed to go on unchecked. Proper treatment of high blood pressure can prevent left ventricular hypertrophy and heart failure.
  
  
• Heart valve problems: The valves of the heart normally keep the blood flowing in the right direction through the heart. Abnormal heart valves impede this forward flow in 1 of 2 ways.
  
  
  • An incompetent valve is a valve that does not close properly when it should and allows blood to flow backward in the heart, "against the current." When blood flows the wrong way across a valve, the heart has to work harder to keep up its output. Eventually, this backed up blood accumulates in the lungs and the body.
    
    
  • A stenotic valve is a valve that does not open properly when it should. Blood flow through the narrowed opening is blocked, creating an increased workload on the heart.
     
• Abnormal rhythm or irregular heartbeat: Abnormal heart rhythms lower the heart's effectiveness as a pump. The rhythm may be too slow or too fast, or irregular. The heart has to pump harder to overcome these rhythm disorders. If this excessively slow or fast heartbeat is sustained over hours, days, or weeks, the heart can weaken, which can cause heart failure.
  
  
• Other conditions may have injured the heart such as thyroid disorders (too much or too little thyroid hormone) or treatments for cancer (radiation or certain chemotherapy drugs).

Next: Congestive Heart Failure Symptoms »

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