Changes seen with heart failure

Inside the normal heart

the walls of the heart stretch and the chambers dilate

the walls of the heart thicken

• Heart failure means the heart is unable to pump blood as well as it should. Heart failure does not mean the heart has stopped working.
• The "poor pump" is unable to keep up with the body’s constant need for oxygen and nutrients during heart falure. In response:
  • the walls of the heart stretch to hold more blood
  • the heart muscle walls thicken to pump more strongly.
  • the kidneys cause the body to retain fluid and sodium. This increases the amount of blood circulating through the heart and blood vessels.
  • your body tries to compensate by releasing hormones that make the heart work harder. Over time, these compensatory mechanisms fail and symptoms of heart failure begin to appear. Like an over-stretched rubber band, the heart’s ability to stretch and shrink back decreases. The heart muscle becomes over-stretched and is unable to pump blood effectively.
• Blood backs up into the arms, legs, ankles, feet, liver, lungs or other organs; the body becomes congested. This is called congestive heart failure.
• Heart failure is a progressive process, even if no new damage occurs to the heart.

Words related to heart failure:

• Ejection fraction (EF): a measurement of the amount of blood pumped out of the left ventricle with each heartbeat. In a normal person, the ejection fraction equals about 50 percent or more. If someone has systolic heart failure, the ejection fraction will equal about 20 to 40 percent, or even less.
• Ventricular remodeling: the changes that occur to the heart’s pumping chamber (ventricle) when someone has heart failure. The inside of the left ventricle gets bigger during heart failure, the walls become thicker and the heart changes shape (becoming more round rather than pear-shaped). These changes worsen the heart’s ability to pump blood, stress the heart and may cause the mitral valve to leak.
• Systolic heart failure (systolic dysfunction): occurs when the heart muscle does not contract with enough force, so there is not enough oxygen-rich blood pumped throughout the body. An ejection fraction less than 40 percent indicates systolic heart failure.
• Diastolic heart failure (diastolic dysfunction): occurs when the heart contracts normally (a normal ejection fraction) but the ventricle does not relax or fill properly, so less blood enters the heart.

What causes heart failure?

Heart failure is most often caused by:

Coronary artery disease (myocardial infarction or heart attack):

Coronary artery disease

Coronary artery disease causes decreased blood flow to the heart muscle. If the arteries become blocked, the heart becomes starved for oxygen and nutrients (ischemia). In a short time, damage to the heart muscle (a heart attack) occurs. The damaged area can not pump normally, causing heart failure.

Other causes of heart failure include:

• Cardiomyopathy: damage to the heart muscle from infection, alcohol or drug abuse, pregnancy or no apparent cause
• Conditions that overwork the heart: high blood pressure (hypertension), valve disease, thyroid disease, kidney disease, diabetes mellitus or heart defect

Sources:

• American Heart Association, 2000 Heart and Stroke Statistical Update, Dallas, Texas, AHA.
• Bishay ES, McCarthy PM, Cosgrove DM, Hoercher KJ, Smediera NG, Mukherjee D, White J, Blackstone EH, Mitral valve surgery in patients with severe left ventricular dysfunction, European Journal of Cardio-thoracic Surgery 17 (2000) 213-221.
• Cleveland Clinic Foundation, Cleveland Clinic Health System Heart Failure handouts
• 1999 Consensus Recommendations for the Management of Chronic Heart Failure, The American Journal of Cardiology, Vol.83 (2A), January 21, 1999.
• McCarthy PM, Surgical Alternatives for the failing heart Cleveland Clinic Foundation, Cleveland, Ohio, 2000.
• Hoercher K, McCarthy P, Young JB Cardiac Transplantation at the Cleveland Clinic Foundation, In (Cecka & Terasaki Eds).Clinical Transplants 1999.
• Topol E. (Ed.) (2000) Cleveland Clinic Heart Book (pp.205-229). New York: Hyperion.
• HeartMate Velvas Patient Handbook, thermo Cardiosystems, Inc. 1995