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Post-Polio Health (ISSN 1066-5331)

Vol. 17, No. 4, Fall 2001

Remarks at GINI's Eighth International Post-Polio and Independent Living Conference, June 2000

Cardiovascular Issues of Polio Survivors

Ruperto D. Mayuga, MD, Assistant Professor of Clinical Medicine/Cardiology, Northwestern University Medical School, Chicago, Illinois

Cardiovascular disease (CVD) is the leading cause of death in both men and women in the United States. One of every 2.4 deaths is attributable to CVD. However, the incidence of CVD in individuals diagnosed with post-polio syndrome is not known.

CVD is often a "silent" disease without significant symptoms until its life-threatening or catastrophic sequelae appear suddenly. All too often, the first manifestation of CVD is sudden death, stroke or heart attack. The need to identify individuals at increased risk early enough to alter its catastrophic course cannot be overemphasized.

Are there reasons to suspect that polio survivors who are experiencing post-polio problems might be at increased risk for CVD?

Yes, certain features such as generalized fatigue, generalized and specific muscle weakness and joint and/or muscle pain may result in physical inactivity – deconditioning, obesity and dyslipidemia. Polio survivors with respiratory difficulties may develop hypoxemia (low levels of oxygen). Any of these circumstances – deconditioning, obesity, dyslipidemia and hypoxemia – can increase the risk for cardiovascular disease.

Furthermore, most polio survivors are at an age when CVD becomes increasingly more likely.

What are the common signs and symptoms of CVD?

CVD signs

A word of caution: The symptoms of CVD overlap with common symptoms of post-polio syndrome. This presents a problem because individuals diagnosed with the syndrome may not recognize cardiovascular symptoms and think that these may just be a progression or altered manifestation of the post-polio symptoms. The resulting delay in diagnosis can be costly.

What tests should I have if I experience some of the above symptoms?

One study, of practical importance to polio survivors, evaluated the cardiovascular autonomic function of individuals who had polio (Borg, 1988) and concluded that there was no significant dysfunction of autonomic nerves despite the presence of progressive muscle atrophy.

This finding becomes important when one considers that many current methods for assessing cardiovascular function and fitness include evaluation of parameters – such as heart rate, blood pressure, heart rate variability, valsalva response, etc. – all of which require an intact autonomic system. The study results suggest that polio survivors in general can use any of a number of standardized tests for cardiovascular risk assessment such as the exercise stress test without a decrease in test sensitivity, provided that due consideration of the presence of muscular dysfunction is made.

For example, an arm ergometer may be used instead of a treadmill as the method of providing the exercise in individuals with lower extremity weakness. There are also non-exercise types of cardiovascular stress testing such as pharmacologic, vasodilator perfusion stress tests (dipyridamole or adenosine stress tests) used in conjunction with nuclear imaging, or a dobutamine stress test. These are the preferred tests for those who cannot perform significant exercise.

Also, make certain that blood pressure, cholesterol/lipid profile, fasting blood sugar (FBS), body weight and an ECG are included in your annual physical examination. A chest x-ray would also be useful periodically to determine heart size and the status of the lungs. More frequent testing as well as additional specific tests (stress tests, echocardiograms, coronary angiograms, etc.) may be needed.

Although there appears to be no large scale studies evaluating whether individuals experiencing post-polio syndrome are at increased risk for CVD, it is probably safe to assume that there may be increased risk in certain individuals who have the traditional risk factors mentioned above. A study of 64 post-polio individuals (Agre, 1990) found that 66% of the men and 25% of the women had hyperlipidemia (high lipid concentration) with men also having low HDL (the "good") cholesterol. These findings underscore the need to actively screen for dyslipidemia and/or hypercholesterolemia (excess cholesterol in the blood; less than 200 total cholestrol is desirable). In addition, deconditioning and obesity was found to be strongly associated with the presence of dyslipidemia. Therefore, it is important to address these issues.

Since CVD is described as a "silent" disease without significant symptoms, what are some of the risks factors that are of major importance to everyone with or without a history of polio?

Risk factors include cigarette smoking, hypertension (high blood pressure), elevated LDL cholesterol (the "bad" cholesterol; less than 100 is optimal), low HDL cholesterol (the "good" cholesterol; 60 or more is optimal), diabetes, male gender, post-menopausal women, family history of premature coronary heart disease, the presence of peripheral arterial occlusive disease, and, last but not least, obesity and physical inactivity.

The presence of multiple risk factors results in more than just additive risk.

How can I avoid physical deconditioning and becoming overweight?

In individuals with identified post-polio symptoms consistent with cardiovascular deconditioning, there has been some hesitation in prescribing an exercise program to improve conditioning because of fears that traditional exercise regimens may lead to further loss of muscle from overuse. The prospect of safely and effectively training PPS subjects was evaluated by a number of investigators. All investigators found that a carefully designed exercise program, which avoided excessive muscle fatigue was able to provide positive results.

Consult your health care professional for appropriate recommendations. In general, exercise has to be started very gradually and at a lower level individually tailored to each individual's physical status and needs. Care should be taken not to over-exercise. Nutritional counseling is also a useful resource.