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Spinal Cord Injury Update

Summer 2009: Volume 18, Number 2

 

SCI and the Risk for Heart Disease

By Joanne Lewin, ARNP, and Cynthia Salzman, MHA

 

Contents

Heart disease in the SCI population

In the United States, cardiovascular disease (CVD) — also called “heart disease”— is the leading cause of death. In past years, people with SCI often died soon after their injury, so it was rare for someone to live long enough to develop CVD. Now that long-term survival is common after SCI, CVD has become one of the most frequent causes of death in the SCI population. There have not been many large studies to address important questions, however, and many controversies remain.

A recent review of the medical research showed that CVD may be no more common in SCI than it is in the general population and that screening and treatment should be the same for both populations (Wilt, 2008). However, factors that increase the risk for cardiovascular disease, such as obesity and physical inactivity, are very common in people with SCI. These factors are also more difficult to treat in people with SCI. Therefore, CVD risks may merit special attention in people with SCI.

What is cardiovascular disease?

Cardiovascular disease (CVD) is a broad term that includes many diseases affecting the heart and blood vessels. The most common form of CVD is the narrowing or blocking of the arteries or blood vessels that supply blood to the heart, called atherosclerosis. It is the major reason people have heart attacks. Understanding your risk for CVD is complicated because there are so many different risk factors involved and there is still so much that is not known about CVD in the SCI population.

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Risk factors for cardiovascular disease

Some risk factors you are simply born with and can’t do anything about, such as sex, ethnicity, and family history (father or brother who had a heart attack before age 55, or mother or sister who had one before 65). You also can’t do anything about your age. Other risk factors are things you might be able to change through diet, exercise, medications and habits. The following are risk factors that can be changed.

Abnormal blood lipids (fats)

Lipids are fat-like substances in the blood and include:

  1. Cholesterol—essential for insulation of nerve fibers and brain tissue and for production of hormones. It comes from diet and is also produced by the liver. After the fat and dietary cholesterol are digested, the liver produces lipoproteins that travel through the blood. These include low density lipoprotein (LDL, the “bad cholesterol”) and high density lipoprotein (HDL, the “good cholesterol”). LDL can cause plaque (fat deposits) to form in the artery walls, which over time can narrow, block or stiffen the arteries
  2. Triglycerides are another form of fat transported by the blood. High levels of triglycerides also cause harm to artery walls.

Although more research is needed, there is some evidence that having an SCI increases the risk of abnormal blood lipids, such as the risk of having a low HDL cholesterol level.

What you can do about it:

Have your lipid blood cholesterol checked annually. Ideal levels of blood lipids vary depending on your risks. General guidelines can be found at websites such as WebMD's “Cholesterol: Understanding the Numbers” (http://www.webmd.com/cholesterol-management/guide/understanding-numbers), but you should discuss your individual goals with your health provider.

Treatment usually starts with therapeutic life changes, such as increasing physical activity and controlling diet. Choose unsaturated fats, which come from vegetable oils, fish and plant food such as nuts and seeds. Avoid saturated fat (mainly from animal products) and trans fats (found in many prepared foods). Cutting down on saturated fat can help lower your LDL level. Add fiber in the form of fruits and vegetables as it helps to move cholesterol and triglycerides out of the blood system. If changes in diet and exercise don’t bring lipids into the desirable range after three months, medications are often recommended. The most commonly used class of medications is called “statins,” which help to lower LDL.

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Smoking

Smoking increases the risk of heart disease two- to four-fold. Smoking injures blood vessel walls, including those that supply blood to the heart muscle. Cholesterol tends to accumulate in the injured blood vessel walls. Smoking also may lower the “good” HDL levels and increase “bad” LDL levels.

What you can do about it:

Quit smoking! Ask your health provider or insurance company about programs that may be available to you for free. Go to www.smokefree.gov for more information on how to quit.

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Diabetes and metabolic syndrome

Diabetes—a condition in which the body cannot make or correctly use insulin—increases LDL cholesterol and the risk for heart disease. Metabolic syndrome is a cluster of risk factors that, if left untreated, may develop into type 2 diabetes. People with metabolic syndrome also have a higher risk of heart disease and stroke. Metabolic syndrome is defined as having three or more of the following:

What you can do about it:

Increase physical activity and lose weight. Work with your health provider to manage these risks. Some studies have shown that the metabolic syndrome associated with SCI can be partially reversed by endurance training such as manual wheelchair or handcycle propulsion, upper body arm ergometry, functional electrical stimulation of the lower extremities, swimming and other adapted modes of training. For more information about fitness options, see our SCI Forum report “Universal Fitness” at http://sci.washington.edu/info/forums/reports/universal_fitness.asp

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Physical inactivity

If you don’t get enough exercise, your body stores extra fat. Too much fat leads to insulin resistance and lower HDL. Exercise can decrease your risk of diabetes, insulin resistance, heart disease and high blood pressure.

What you can do about it:

Get moderate-intensity exercise 5–7 times a week for 30 minutes a day. Exercise is more challenging when you have SCI because of the physical limitations of paralysis, difficulty raising heart rate with exercise, and lack of access to exercise opportunities. The National Center on Physical Activity and Disability Web site (www.ncpad.org) has many resources to help you become more active, such as exercise videos for people with paraplegia and tetraplegia. Consult with your health provider on ways you can safely increase you physical activity.

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Overweight

Being overweight is a common problem in the SCI population, and excess fat increases the risk of high blood pressure and diabetes. Body mass index (BMI)—the ratio of height to weight—is often used to determine whether someone is overweight or obese. However, most people with SCI have lost “lean body mass” due to muscle atrophy (shrinking or wasting) and even due to loss of calcium from bones. Therefore, someone with SCI can have an excessive amount of body fat but still have a normal weight-to-height ratio. For this reason, BMI is not a good way to determine obesity in the SCI population. In general, people with SCI should weigh 10% less than people of similar height in the general population, but ideal standards have not been developed.

What you can do about it:

A combination of diet, exercise and behavior modification have shown results, but currently little is known about the best way to manage obesity in the SCI population. You may want to talk with a nutritionist who has worked with SCI patients. Reduce calories by eating smaller portions. Limit alcohol if you drink. For more information, see our SCI Forum report “Nutrition Guidelines for People with SCI” at http://sci.washington.edu/info/forums/reports/nutrition.asp.

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High blood pressure

High blood pressure increases the risk for heart disease and stroke if it is too high over months or years. This chronic high blood pressure is different from the temporary increase in blood pressure that occurs during episodes of autonomic dysreflexia (temporary blood pressure elevation due to pain or noxious stimulation below injury level). These brief periods of blood pressure elevation probably do not increase the long-term risk for cardiovascular disease.

What you can do about it:

Chronic high blood pressure can be lowered through diet, exercise, weight loss and medications. If you have chronic high blood pressure, talk with your health provider to determine your blood pressure goals.

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Resources—Where to go for more information

References

  1. Meyers J, Lee M, Kiralti J: Cardiovascular disease in spinal cord injury: An overview of prevalence, risk, evaluation and management. Am Journal of physical medicine & rehabilitation. 2007.
  2. Wilt TJ, Carlson FK, Goldish GD, et al. Carbohydrate & Lipid Disorders & Relevant Considerations in Persons with Spinal Cord Injury. Evidence Report/Technology Assessment No. 163 (Prepared by the Minnesota Evidence-based Practice Center under Contract No. 290-02- 0009.) AHRQ Publication No. 08-E005. Rockville, MD. Agency for Healthcare Research and Quality. January 2008. http://www.ahrq.gov/downloads/pub/evidence/pdf/carblipspinal/carblip.pdf
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