You probably don’t even realize it, but as you go about your day, immersed in your various activities—sitting, standing, running or sleeping—your heart rate and your blood pressure change. This happens automatically because your autonomic nerves control these functions. But if these nerves are damaged, your heart rate and blood pressure may be less responsive to these changing needs. If you have autonomic neuropathy, you may develop orthostatic hypotension, a condition in which your blood pressure drops very low when you stand up. You may also develop an abnormally high heart rate, because of damage to the nerves that control heart rhythm. Another problem with autonomic neuropathy is that you could have a so-called silent heart attack, a heart attack in which you are unable to feel the warning signs due to damage to the nerves that transmit pain signals.
When you stand up suddenly, blood tends to pool in your legs because of gravity. When this happens, less blood returns to your heart and is pumped out by your heart, and your blood pressure falls. Normally, your body rapidly responds to this by signaling the heart to beat faster and stronger, constricting your blood vessels, and blood pressure is quickly restored. However, if you have neuropathy, the signal to change the heart rate and blood pressure is impaired and low blood pressure results.
Orhostatic hypotension is marked by a feeling of faintness, light-headedness, dizziness, confusion, blurred vision, or even fainting and convulsions. This is most likely to happen when you get out of bed suddenly or stand up after sitting for a long period of time. The condition is made worse when you are tired, have recently exercised, have eaten a heavy meal or drunk alcohol.
What You Should Do
If you frequently feel the symptoms of hypotension when standing suddenly, tell your doctor or health care provider. It is important to first rule out any other condition that may be causing the same problem. If you experience any episode of fainting or convulsions, seek emergency help right away. If you have a history of high blood pressure it is especially important to alert your doctor to this condition.
Your doctor will diagnose orthostatic hypotension by checking your blood pressure in sitting, standing, and reclining positions. If your blood pressure goes down when you stand up but returns to normal when you lie down, you most likely have orthostatic hypotension.
If you diagnosed with orthostatic hypotension, you can take certain precautions to minimize the symptoms. Avoid standing up suddenly from a sitting or reclining position. If you are lying down, sit up for a minute or two before standing. If you are sitting, stand up slowly. Also avoid sitting or standing still for long periods of time. If you are sitting, get up every now and then and walk around. If your condition occurs because of prolonged bed rest, sitting up in bed from time to time may help. Elevating the head of your bed may also help.
If low blood pressure is occurring because blood is pooling in your legs, then you might find it helpful to wear waist-high support stockings of fitted elastic hose. Make sure to put the stockings on before you get up. In severe cases, your doctor may suggest a total body stocking.
Trying to keep your blood pressure high enough when you stand up must be balanced with not letting it get too high at other times. Make sure that your salt intake is high enough to keep your blood volume large enough. But check with your doctor before you make any changes in your diet, especially if you have high blood pressure.
Your doctor may also suggest one of several medications:
Fludrocortisne (Florinef) may help expand your blood volume, which will help prevent your blood pressure from falling too low. However, these drugs can increase the risk of developing high blood pressure or congestive heart failure. Alert your doctor right away if you notice any kind of edema, or swelling. Other medications can work more directly on the blood vessels. These include phenylephrine, ephedrine, Neo-Synephrine nasal spray, beta-blockers, clonidine, octreotide and Epogen.
Some patients may find relief with propranolol (Inderal). Some people also experience low blood pressure after eating, especially in the morning. This condition can be helped by octreotide (Sandostatin)
Abnormal Heart Rate
If neuropathy affects the nerves that control your heart rate, you may have an excessively high heart rate, whether you are standing, sitting, exercising, resting or sleeping. Your heart rate does not change to accommodate the varying needs of your body.
You probably won’t really feel any pain if neuropathy affects your heart rate. However, you may get the feeling that your heart rate is racing, even when you are resting. You can check your pulse before and immediately after exercising, as well as an hour after exercising. To do this, find a pulse in your wrist, neck or other convenient location. Count the beats in a 15-second period and multiply by 4. This gives you your heart rate in beat per minute.
Your heart rate should increase during and immediately after exercising (by as much as a 2- to 3-fold, depending on how strenuous the exercise). But after an hour’s rest, your heart rate should return to pre-exercise levels. If your heart rate remains high all the time and does not change much (more than 15%) in response to various activities and stress, then you may have neuropathy.
What You Should Do
If you suspect that your heart rate is abnormally high, talk to your doctor. For most people, a normal heart rate is in the range of 60 to 100 beats per minute. It can rise to 120 to 180 beats per minute during exercise. For younger people and those who are physically fit, the resting heart rate can be much lower. If your heart rate is consistently on the high end of this range, or higher, tell your doctor. You will most likely be tested to see if this is a neuropathy-related condition. This condition is potentially serious, for it increases your risk of irregular heart beat and it may prevent you from feeling the pain of the symptoms of heart attack.
Your doctor may check for changes in your heart rate as you breathe deeply. Or your heart rate may be measured before and during exercise. You may be hooked up to an electrocardiogram or other specialized computer program during this evaluation.
Unfortunately, few satisfactory remedies are available to control the abnormal heart rate due to autonomic neuropathy. Several experimental therapies for neuropathy in general show some promise, and studies are ongoing. These therapies include nutritional factors and dietary supplements, such as vitamins A, B12 and B6, aldose reductase inhibitors, myo-inositol and evening primrose oil. However, none of these therapies is proven to be effective in widespread studies. Talk to your doctor about the best way to manage cardiac problems resulting from diabetic neuropathy.
Because there are few treatments to alleviate the cardiac problems resulting from autonomic neuropathy, it is especially important to keep blood glucose levels under control. If you have any of the symptoms associated with neuropathy, especially with cardiac complications, you may want to consider maintaining tight control of your blood glucose level. Talk to your doctor or diabetes educator about developing an intensive therapy program
Silent Heart Attack
A major complication of diabetic neuropathy is the so-called silent heart attack. Often people at risk for heart attack experience warning signs, such as angina or heart pain. But if your neuropathy is severe, you may not receive any warning that a heart attack is impending. If neuropathy is severe, you may even have a heart attack without experiencing any pain
Unfortunately, with autonomic neuropathy that affects cardiovascular system, you may not really feel any of the symptoms of a heart attack. Typically, you feel crushing pain in the chest or arms if you are having a heart attack. But with neuropathy, you may not feel this pain at all. The only symptoms you may feel are perspiration, shortness of breath, or fatigue. Another sign that you could be having a heart attack is unexplained episode of hyperglycemia, or blood glucose levels that go suddenly out of control.
What You Should Do
If you have any symptoms of a heart attack, with or without chest pain, call for emergency help at once, especially if you have any history of neuropathy. If you are at risk for a heart attack, talk to your doctor in advance about what to look for and what you should do if you think you are having a heart attack. Do not worry about false alarms. This is a life-threatening situation that should receive immediate attention.
Unfortunately, there are few treatments available to deal with the neuropathy that can lead to a silent heart attack. However, if you are at risk for a heart attack or have had a heart attack, there are several treatments that are mainly aimed at preventing another heart attack from occurring. These include surgery and drug therapy.
The best way to prevent a silent heart attack from occurring is to take steps to prevent neuropathy from developing and to prevent heart disease. Have your cholesterol levels checked, and if they are high, take steps to lower your cholesterol level through diet and exercise. If you smoke or drink alcohol, stop. Talk to your doctor about an exercise program that will work for you.
Talk to your dietitian about developing a meal plan that will keep your cholesterol and lipid levels low and your blood glucose levels in control. The DCCT showed that you can lower your risk of neuropathy by 60% and your risk of cardiovascular disease by 35% following a program of intensive therapy. Talk to your doctor about whether this plan would work for you and how to go about implementing it. Even if you don’t practice intensive therapy, maintaining your blood glucose levels as close to normal as you can will help control both neuropathy and cardiovascular disease.
Sources and References
The Diabetes Problem Solver—Quick Answers to Your Questions About Treatment and Self-Care by Nancy Touchette
Management of Orthostatic Hypotension by Jose-Alberto Palma and Horacio Kaufmann
Autonomic Peripheral Neuropathy by Roy Freeman