Heart Rate Abnormalities

The number of times the heart beats per minute, the rhythm, and the strength of each beat can provide an indicator of overall heart health. A healthy heartbeat is steady and strong, but common heart rate abnormalities--like arrhythmia, heart murmur or heart fibrillations--can occur when the heart weakens, speeds up, slows down or beats with an irregular rhythm.

Healthy Heart Rate Sounds

The healthy heart beats about 60 to 100 times per minute. Highly trained and conditioned athletes may have lower, but still normal, heart rates. Each chamber cycles through a systolic period in which it contracts to expel blood, and a diastolic period when the chamber relaxes and refills.

At the beginning of the cycle, the left and right atrial chambers at the top of the heart receive an electrical signal and contract. Each atrium pushes its blood supply to the ventricle below, and each ventricle expands as it fills. Then the electrical signal travels to the ventricles, and causes the left ventricle to contract, followed quickly by the right. As the ventricles empty into the pulmonary artery and the aorta, the atria refill and the cycle begins again.

If you listen to a healthy heart using a stethoscope, you can hear the cycle of contraction and relaxation, which is described as a "lub-dub" sound. Large arteries under the delicate skin of the wrist or throat will also reveal the activity of the heart as blood pulses through them. In a healthy person, the pulse is strong and easy to feel with the fingertips.

Common Heart Rate Abnormalities

Some of these heart rate abnormalities suggest serious conditions that require attention. Others are not as harmful, but are easier to manage when they are recognized and monitored. Common heart rate abnormalities include:

• Arrhythmia: Some heart rate abnormalities happen when the heartbeat is too rapid (tachycardia), too slow (bradycardia) or contains extra beats. An arrhythmia often results from electric signals moving along non-standard pathways from the atrial to the ventricular chambers. This can take place when too many pathways exist between the nodes, the natural pacemakers that generate the electrical signals.
• Heart fibrillations: A very common form of arrhythmia is atrial fibrillation, a form of heart fibrillation in which too many signals initiate at the primary node (the SA node) and spread in a disorganized way across the atria. The atrial contractions then become confused and irregular. Another reason for atrial fibrillation is due to abnormally increased sizes of the atrial chambers.
• Heart murmur: A heart murmur can happen when blood moving through the heart becomes blocked or flows backwards. This can result in an extra sound upon auscultation, which is sometimes described as a "whooshing." Many heart murmurs are harmless, but sometimes they can lead to serious complications and need to be corrected.

Treatment for Heart Rate Abnormalities

Medications for arrhythmias and heart murmur usually target the underlying problem. Treatment can involve drugs that strengthen the contractions, lower body fluid, remove blood clots or reduce blood pressure.

In addition to medication, abnormal heart rhythms can sometimes be treated with applied electrical shocks, catheters or implantable devices like pacemakers.

Resources

Cleveland Clinic. (2010). Common types of arrhythmias. Retrieved November 1, 2010, from http://my.clevelandclinic.org/heart/disorders/electric/types.aspx

Cleveland Clinic. (2010). Management of arrhythmias (abnormal heart beats.) Retrieved November 1, 2010, from http://my.clevelandclinic.org/heart/disorders/electric/arrhythmia.aspx

Mayo Clinc Staff. (2010). Heart arrhythmias basics. Retrieved November 1, 2010, from http://www.mayoclinic.com/health/heart-arrhythmias/DS00290

Mayo Clinc Staff. (2010). Heart murmur basics. Retrieved November 1, 2010, from http://www.mayoclinic.com/health/heart-murmurs/DS00727

Mayo Clinic Staff. (2010). What is a normal resting heart rate? Retrieved November 1, 2010, from http://www.mayoclinic.com/health/heart-rate/AN01906

National Heart, Lung and Blood Institute. (2010). How the heart works. Retrieved November 1, 2010, from http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html