Using Clonidine to Improve Leg Weakness in People With Heart Failure

Clonidine and the Skeletal Myopathy of Heart Failure

People with heart failure often have weakness in their leg muscles. This study will determine whether the leg weakness is due to very high adrenaline levels and whether the medication clonidine can improve leg weakness.

Heart failure is a common condition, affecting approximately 5 million people in the United States. People with heart failure are encouraged to exercise and lose weight. However, many people with heart failure develop weakness in their leg muscles, which can make exercise difficult. Increased sympathetic nerve activity, which involves the nerves that carry adrenaline, also occurs in people with heart failure. It is possible that the increased sympathetic nerve activity may actually cause the leg muscle weakness. Clonidine, a medication used to treat high blood pressure, has been found to decrease sympathetic nerve activity. This study will further examine the connection between leg weakness and sympathetic nerve activity. It will also evaluate the effectiveness of clonidine at decreasing leg weakness in people with heart failure. Results from this study may explain why some people with heart failure are unable to exercise and may help to identify ways in which leg strength can be increased.

This study will enroll people with heart failure. Participants will be randomly assigned to wear either a clonidine patch or a placebo patch for 3 months. Participants will wear the patch on their upper arm, and they will replace the patch each week. At study visits at baseline and Month 3, participants will undergo the following procedures:

• Sympathetic nerve activity recording, which will record nerve activity in the lower leg, using small electrodes inserted through the skin
• Muscle biopsy, in which a small piece of muscle tissue will be obtained from participants' legs
• Heart rate and blood pressure measurements
• Arterial baroreceptor measurements, in which the nerves in the body that respond to changes in blood pressure will be examined while participants receive different medications to increase and decrease their blood pressure
• Echocardiography to obtain images of the heart
• Magnetic resonance scan of the leg
• Passive exercise procedure, in which study researchers will conduct an arm exercise with participants

There will be no follow-up visits.

Inclusion Criteria:

• Heart failure

Exclusion Criteria:

• Currently on Coumadin therapy
• Experienced a heart attack in the 3 months before study entry
• Medically unable to receive clonidine
• Advanced kidney or liver disease