Cardiovascular Issues And The Post-polio Syndrome
by Rupert D. Mayuga, M.D.
This paper was presented at the International Polio Network's Eighth International Post-Polio and Independent Living Conference in St. Louis, Missouri, June 8-10, 2000.
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 it. In addition, it results in substantial morbidity, accounting for more than 6 million hospital discharges per year in this country.
The actual incidence of CVD in individuals suffering from post-polio syndrome (PPS) is not known. However, there is reason to suspect that individuals with PPS might be at increased risk. Certain features of PPS such as generalized fatigue, generalized and specific muscle weakness, joint and/or muscle pain may result in physical inactivity deconditioning, obesity and dyslipidemia. Respiratory difficulties may result in hypoxemia. Any of these can predispose those with PPS to increased cardiovascular risk. Furthermore, most individuals with PPS are now at an age group where CVD such as heart attack, stroke and heart failure become increasingly more likely. Common symptoms and signs of CVD include exertional chest discomfort, exertional and nonexertional shortness of breath, sudden shortness of breath and/or chest discomfort after lying down, swelling of the ankles and legs, heart enlargement, palpitation, loss of consciousness and easy fatigability. It is evident that there are symptoms of CVD that overlap with common symptoms of PPS. This could present a problem since individuals suffering from PPS may not recognize cardiovascular symptoms by thinking that these may just be a progression or altered manifestation of PPS symptoms. The resulting delay in diagnosis can be costly. It is important to emphasize that 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 a heart attack. The need to identify individuals at increased risk early enough to alter its catastrophic course cannot be overemphasized.
Available information on heart disease and PPS in the scientific literature is regrettably limited. Some interesting studies, however, may be of practical importance to PPS patients. One such study evaluated the cardiovascular autonomic function of subjects with antecedent poliomyelitis (Borg et al) 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 individuals with PPS 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 PPS 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 - echo stress test. These are the preferred tests for those who cannot perform significant exercise.
Apart from cardiac stress testing, there are also an increasing number of ways to evaluate cardiovascular risk. Evaluation for coronary risk factors is of major importance to everyone with or without a history of PPS. Risk factors include cigarette smoking, hypertension, elevated LDL cholesterol (the `bad'' cholesterol), low HDL cholesterol (the ``good'' cholesterol), diabetes, male gender (and 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. Newer tests with possible utility in further defining increased risk for future cardiovascular events (i.e. heart attack, stroke) are currently under consideration. These include carotid artery duplex scanning, electron beam CT, ultrasound-based endothelial function studies, ankle/brachial blood pressure ratios, MRI techniques and testing for hs CRP, a possible marker of increased risk for coronary atherosclerotic plaque instability. Although there appear to be no large scale studies evaluating whether individuals suffering from PPS 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 earlier. A study of 64 post-polio patients (Agre JC et al) found that 66% of the men and 25% of the women had hyperlipidemia with men also having low HDL cholesterol. These findings underscore the need to actively screen for dyslipidemia and/or hypercholesterolemia. In addition, deconditioning and obesity was found by Agre et al to be strongly associated with the presence of dyslipidemia. Therefore, it is important to address these issues in individuals with PPS.
In individuals with identified PPS 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 (Kriz JL et al, Jones DR et al, Owen RR et al). All investigators found that a carefully designed exercise program that avoided excessive muscle fatigue was able to provide positive results. Jones DR et al and Owen RR et al used lower extremity exercise. Kriz JL et al showed that PPS subjects can use upper extremity exercise (using an arm crank ergometer) for 20 minutes three times a week to achieve a significant improvement in cardiovascular conditioning (19% improvement in V02 max in the study). A very gradual training period of 16 weeks was used to allow all PPS subjects to reach a consistent exercise level and to avoid muscle damage from overuse. The results of these studies support the need to develop safe, effective and easily accessible exercise programs for PPS individuals. This has the advantage of allowing the benefits of cardiovascular conditioning without the potential risk of further muscle damage.
- Determine if you have any of the common signs and/or symptoms of cardiovascular disease.
Consult your health care professional as soon as possible if you have any of the above signs and/or symptoms.
- CVD signs: Enlarged heart, swelling of the ankles or legs, unusual/ excess weight gain, wounds that do not heal well.
- CVD symptoms: Chest discomfort (pain, pressure, squeezing, heaviness, etc.) especially if brought on by exertion and relieved by rest, shortness of breath with minimal exertion or upon lying down, palpitation or irregular heart beats, severe dizziness or loss of consciousness, sudden weakness or paralysis of one part of the body, sudden slurring of speech or loss of vision, frequent nocturnal urination, unusual and progressive fatigue, leg pain/ discomfort with walking.
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 recommended as needed.
Avoid physical deconditioning and becoming overweight. Consult your health care professional for appropriate recommendations. In general, exercise has to be started very gradually and at a lower level and individually tailored to each individual's physical status and needs. Care should be taken not to over exercise. Nutritional counseling is a useful resource.
Rupert D. Mayuga, MD is Assistant Professor of Clinical Medicine-Cardiology, Northwestern University Medical School, Chicago, Illinois.
Used by Permission. Presented at the Eighth International Post-Polio and Independent Living Conference, June 8-10, 2000, sponsored by Gazette International Networking Institute (GINI). www.post-polio.org; firstname.lastname@example.org
- American Heart Association. 1999 Heart and Stroke Statistical Update. Dallas, Tx: American Heart Association; 1998.
- Smith Jr. SC, Greenland P, Grundy SM. AHA Conference Proceedings: Beyond Secondary Prevention: Identifying the High-Risk Patient for Primary Prevention. Circulation, January 4 / 11, 2000
- Borg K, Sachs C, Kaijser L. Autonomic cardiovascular responses in antecedent poliomyelitis. Acta Neurol Scand. 1988:77:402-408.
- Agre JC, Rodriguez AA, Sperling KB. Plasma Lipid and Lipid Concentrations in Symptomatic Postpolio Patients. Arch Phys Med Rehabil Vol 71, May 1990.
- Kriz JL, Jones DR, Speier JL, Canine JK, Owen RR, Serfass RC. Cardiorespiratory Responses to Upper Extremity Aerobic Training by Postpolio Subjects. Arch Phys Med Rehabil Vol 73, January 1992.
- Jones DR, Speier JL, Canine JK, Owen RR, Stull GA. Cardiorespiratory responses to aerobic training by patients with post- poliomyelitis sequelae. JAMA 1989;261:3255-8.