11
Heart Health
DId You Know That your injury significantly increases your risk of heart attack and stroke compared to your nondisabled contemporaries? The reasons are unknown, but the possibilities include chronic inflammation (frequently associated with obesity), autonomic dysfunction (especially blood pressure oscillations), and the fact that the greatest risk for a heart attack or stroke is having a history of either one.
Aggressive prevention (and treatment, if needed) of heart disease and its risk factors should now be part of your daily routine. The risk factors for heart attack or stroke are the same for you as they are for the rest of the population—smoking, high total cholesterol, high blood pressure, a family history of heart attack and stroke, and poorly controlled type 2 diabetes—but they now present an even greater danger to you. So, if any one of these descriptions applies to you, it’s time to address them.
In addition to quitting smoking (if you smoke), eating a healthy diet and getting regular exercise are at the top of the prevention list. If it is determined that you should be taking medicine to lessen your risk factors, your doctor will discuss the risks of these drugs with you, since the side effects can be greater after ANI. For example, hypertension is a major risk factor for heart attack and stroke. However, in the presence of autonomic dysfunction, your blood pressure can rapidly go down. The autonomic nervous system regulates your heart rate, which should increase when your blood pressure goes down, but may fail to do so after your injury.
The Cardiovascular System
Anatomy: The cardiovascular system (Figure 23) refers to the heart, blood vessels, and blood; it includes the major vessels that supply the abdomen, legs, arms, brain, and heart. In SCI, bleeding into the spinal cord compresses the nerves and deprives them of oxygen; in stroke, clotting of a blood vessel due to atherosclerosis (fat buildup and inflammation in the artery wall) or bleeding through a hole in the artery wall (hemorrhage) deprives nerves of oxygen and releases toxic substances that kill nerves; and in TBI, both bleeding and clotting contribute to nerve damage and nerve death. Though not explicitly part of the cardiovascular system, the kidneys are crucial for cardiovascular health; kidney dysfunction causes hypertension, which damages vessels, making them susceptible to atherosclerosis, which contributes to heart attack and stroke.
Figure 23. Cardiovascular system
Heart Problems
Cardiovascular disease (CVD) is the leading cause of death in the US, and it’s also responsible for the greatest number of deaths in those who have experienced an ANI. CVD includes stroke, aneurysm, coronary artery disease (CAD), heart attack, peripheral vascular disease, heart failure, and arrhythmias. Traditional risk factors cause even more harm in people with ANI.
Relative Risk of CVD in ANI
The relative risk of CVD varies widely depending on whether you’ve had an SCI, TBI, or stroke. If you’ve had a stroke, you’re at increased risk for a second stroke. If you’ve had a SCI, the increase in CVD is largely related to heart attacks caused by atherosclerosis in the coronary arteries (CAD). As a cardiologist, I believe that the primary reason for increased CAD is autonomic dysfunction. If you’ve had a stroke, the cause in 85 percent of people is an ischemic stroke, which is due to atherosclerosis in the arteries of the brain. The larger vessels, such as the carotid and the middle cerebral arteries, are most susceptible to atherosclerosis. This is especially unfortunate because blood flow from these vessels provides nutrients and oxygen to almost 25 percent of your brain. If you’ve had a TBI, there are few long-term risks of CVD, except if you have autonomic dysfunction.
It’s important to understand that you can achieve a dramatic reduction in your risk of death from CVD or CAD by modifying your lifestyle. If anything in the following list (ranked from highest to lowest risk) has your name on it, it’s time to make some changes:
• type 2 diabetes, both insulin-requiring and treatable with drugs
• smoking
• high total cholestrol
• hypertension
• overweight and obesity
• unhealthy diet
• physical inactivity
Type 2 diabetes: If you have type 2 diabetes, your body either resists the effects of insulin, which regulates the movement of sugar into your cells, or doesn’t produce enough insulin to maintain normal glucose levels. It’s commonly associated with obesity. Diabetes increases the risk of CAD and heart attack by three to four times. High levels of circulating glucose damage blood vessels throughout the body, accelerating the process of atherosclerosis in the heart, brain, and kidneys. Exercise can help avoid this, because it stimulates uptake of glucose by your muscles, but you may not be able to exercise very well after your injury. Plus, the majority of skeletal muscle mass is found in the legs, and both SCI and stroke frequently cause atrophy of the leg muscles.
Treating type 2 diabetes is more difficult if you’ve suffered an ANI. While there are many effective medications for lowering glucose that have beneficial effects (decreasing heart failure and CVD events), others have harmful side effects (increasing fluid in your legs, low blood sugar, skin rash or itching, sensitivity to sunlight, upset stomach, and weight gain). Therefore, the choice of medication needs to be individualized, something your primary care physician and a diabetes specialist (an endocrinologist) can determine.
Smoking: Smoking is one of the major risk factors for CVD, and the risk is strongly related to the number of cigarettes you smoke each day and number of years you’ve been smoking. Cigarette smoke causes inflammation in the blood vessels and directly activates inflammatory white blood cells, leading to CVD. The treatment is simple: Stop smoking! I know, that’s easier said than done. Smoking is addictive, so stopping can be difficult. But it’s worth the effort; the benefits are rapid, and within five years of quitting smoking, a study showed that participants had a 13 percent reduction in the risk of death from all causes, a 27 percent reduction from stroke, and a 47 percent reduction from heart disease–related deaths.1
To quit smoking, set a quit date and talk to your doctor in advance. A two-pronged approach is best: 1) Change habits that trigger your desire for a cigarette, and 2) Try a smoking-cessation medicine. If you always have a cigarette after lunch, for example, take a five-minute walk instead. Ask your doctor for a medication that will help diminish the craving for cigarettes and the symptoms of withdrawal, such as anxiety. Many doctors use Wellbutrin (bupropion) and Chantix (varenicline), because they appear to be more effective than over-the-counter therapies such as nicotine patches and gum. Start these medications at least two weeks before your quit date; otherwise, the withdrawal symptoms that are greatest in the first three days are more likely to cause you to give up. It’s so much harder to quit if someone in your household smokes, so make it a family affair and vow to quit together. Support each other through the transition to becoming nonsmokers.
High cholestrol: Total cholesterol should be the initial blood test because it does not require you to fast. Cholesterol is an essential building block for all of our cells. Your liver makes proteins called lipoproteins that carry cholesterol to your cells for their use. When we talk about our cholesterol levels, we’re referring to two important lipoproteins: 1) low-density lipoprotein (LDL, the “bad” one), and 2) high-density lipoprotein (HDL, the “good” one). We measure blood cholesterol because of the direct relationship between the level of LDL and the presence of CVD. If you can’t bring high LDL levels down to the normal range by making changes to your diet and lifestyle, your doctor will prescribe medication to help.
Hypertension: Hypertension, or high blood pressure, is a major risk factor for CAD and stroke, which is why it’s important for you to pay attention to your numbers. Treat if they are greater than 130/90. The first actions in treating hypertension are lifestyle modifications: consuming a low-salt diet, regular exercise, weight loss, decreasing stress and improving your coping skills, and getting plenty of sleep. If these methods aren’t successful in reducing your blood pressure, your doctor may start anti-hypertensive drug therapy.
Overweight and obesity: The best way to determine if you are at an unhealthy weight is by assessing central obesity, which looks at the body’s distribution of fat. Increased central obesity is indicated by a waist circumference greater than 40 inches (100 cm) in men and greater than 35 inches (90 cm) in women. Carrying more fat around the waist increases your CVD risk. Treating obesity and maintaining weight loss is difficult, but exercise and a healthy diet are the best routes to take. If you are capable of regular exercise, moderate to vigorous intensity physical exercise for at least forty minutes most days of the week is recommended. A Mediterranean diet (see page 95) that emphasizes vegetables, fruits, legumes, and whole grains is an excellent way to maintain an optimal weight.
Physical inactivity: Exercise is key to a healthy lifestyle for anyone, and that’s particularly true after your injury. Make it part of your weekly routine. Workouts of thirty to sixty minutes per session, three to seven times a week, are essential for your heart health. Your exercises can include hand-crank ergometry, hand cycling, swimming, and functional electrical stimulation of muscles. If you have incomplete neurologic deficits, like me, you may be able to do more intense exercise, such as cycling using a recumbent tricycle; walking with a cane, crutches, or walker; adaptive sit-skiing; kayaking; and rowing. Body weight–supported walking overground or treadmill training is excellent, but it requires the assistance of one or more therapists.
Orthostatic hypotension: This problem is a decrease in systolic blood pressure (the first number of the two that measure your blood pressure) of more than 20 or a decrease in diastolic blood pressure (the second number) of more than 10 when going from lying down to sitting up. Typical symptoms are fatigue, weakness, dizziness, light-headedness, and blurred vision. When I stand up and my blood pressure drops, I experience blurred vision and need to sit down quickly. There have been several occasions when I’ve fainted and fallen, due to autonomic dysfunction.
It’s normal for your blood pressure to decrease when you stand up, because blood accumulates in the legs. Your autonomic nervous system (ANS) senses the drop and activates the sympathetic nervous system to increase heart rate, stimulate contraction of the heart, and decrease blood flow to the gut and skin. But after your injury, your body may not be able to sense the drop or activate the ANS. The good news is there are many simple treatments, including compression stockings on the legs, an abdominal binder, adequate fluid intake, avoiding alcohol and caffeine, and increased salt intake. Rarely, drugs, such as alpha adrenergic agonists (midodrine), or mineralocorticoid agents (fludrocortisone), are needed to address the problem—you can discuss this with your doctor.
Diagnosis and Evaluation of Heart Disease
People with ANI often have unusual symptoms or no symptoms of coronary artery disease (CAD) at all. Therefore, the best tests don’t depend on symptoms—but they can be seen with imaging. CAD testing frequently involves a stress to increase heart rate, typically walking on a treadmill. But if you’re unable to walk, the stress will have to be induced by arm exercise or by using a drug to speed up the heart.
Echocardiogram: An echocardiogram is an ultrasound measurement of the heart. It’s a noninvasive test that indicates the contractility of the heart, the structure of its upper and lower chambers, and the heart valves. The velocity of blood flow can be measured using the Doppler technique, which shows whether the heart valves are normal, leaking, or narrowed. This information is important, because CAD can be diagnosed if regions of the heart show diminished contraction.
Exercise tolerance test (ETT): Making the heart work harder increases the likelihood of detecting CAD, so ETT is the usual approach. If you are physically able, you’ll wear electrocardiogram (ECG or EKG) electrodes and start to walk on a treadmill at a slow pace. Every three minutes, the pace is increased until you become tired or have symptoms like chest pain, left arm pain, or shortness of breath. If CAD is present, the ECG will show specific changes. The ETT can be combined with echocardiography or with injection of a nuclear medicine to provide images of the regions most affected by CAD. These tests are also routine after stroke.
Computerized tomography (CT) calcium score: A cardiac CT scan for coronary calcium is a noninvasive way of obtaining information about the presence, location, and extent of calcified atherosclerosis in the coronary arteries. Because calcium is a marker of CAD, the amount of calcium detected on a cardiac CT scan is a helpful prognostic tool. The more coronary calcium you have, the more likely you will have CAD problems in the future.
Cardiac catheterization and angiogram: To locate the exact places in your coronary arteries where the atherosclerosis has increased so much that it narrows the artery, your doctor will perform imaging of the coronary arteries. A catheter is inserted into the openings of the three coronary arteries, and X-ray contrast dye is injected to show where there is significant narrowing (a 70 percent or greater decrease in the diameter of the artery).
ANI-Specific Heart Health Problems
SCI
Autonomic dysreflexia (AD): If your SCI is above T6, you may experience AD, which is characterized by increased blood pressure (20 to 40 mm Hg above baseline), severe headache, and loss of skin color below the level of injury with flushing and sweating above the level of lesion. The major risk of AD is extreme elevations of blood pressure (250 to 300 mm Hg systolic, and 200 to 220 mm Hg diastolic). AD can cause seizures and bleeding in the brain from a ruptured blood vessel. As a result, everyone with SCI should carry an automated blood pressure cuff (Omron is a good brand), to check their blood pressure when they experience AD symptoms. AD is usually provoked by dysfunction of an internal organ, leading to severe activation of the ANS. Common causes include bladder distention, fecal impaction, and pressure sores (more on this in chapter 13). Treatment of AD should be focused on identifying and fixing the cause simultaneously, and on lowering the blood pressure. If the problem is bladder distention, a Foley catheter should be inserted to drain the bladder; if the cause is fecal impaction, an enema should be administered immediately. There are many ways to lower blood pressure, but intravenous injection is mandatory, in my opinion. At my hospital, we commonly use intravenous labetalol.
Bradycardia: Bradycardia is a slower-than-normal heartbeat. If you have an SCI, you are more susceptible to bradycardia. This is usually asymptomatic. If you rapidly change position from lying down to standing up, the usual response is for your heart rate to increase to maintain your blood pressure. With bradycardia, if your heart rate doesn’t go up, you’ll feel dizzy and might even faint.
No nighttime decrease in blood pressure: In most healthy people, blood pressure drops during sleep. But this decrease may not occur if your ANS is impaired, especially if you have a cervical SCI. Because this loss of the nighttime dip is associated with more CVD events, you should measure your blood pressure continuously for one to two days with an ambulatory blood pressure monitor if you have symptoms of autonomic dysfunction.
Temperature regulation: It’s the job of the ANS to regulate and maintain a body temperature of 98.6°F (37°C), especially when the air temperature increases or when you become hot due to exertion. The two primary ways the ANS cools down the body are by diverting blood flow to the skin and increasing sweating. But both of these responses are impaired after SCI above T6 due to autonomic dysfunction. Failure to maintain normal body temperature can result in heat stroke, which is a body temperature greater than 104°F (40°C) and mental confusion. If not treated promptly, heat stroke can rapidly lead to severe organ damage and death. If you suspect you have heat stroke, seek emergency treatment; doctors will administer intravenous infusion of cold saline and place you in an ice water bath.
Stroke
Atrial fibrillation (AF): AF is the most common cause of an abnormal heartbeat (arrhythmia) in adults, and it significantly increases the risk of stroke. AF refers to the loss of the normal electrical and contractile properties of the atrium (the upper chamber of the heart). It has several causes, including hypertension, congestive heart failure, valvular heart disease, and heart attack. As a result, the normal contraction of the atrium is lost, so blood can clot, especially in the atrial appendage, a small pouch at the top of the atrium. These clots can dislodge and travel from the heart to the carotid arteries, then onward to the brain, where they cause a stroke, by blocking either a major artery or multiple smaller arteries. The best treatment for AF is individualized, based on the underlying cause, coexisting medical conditions, frequency of AF, and patient preferences. Therefore, consultation with a cardiologist is necessary if you are diagnosed with this condition.
| Condition | Points | |
| C | Congestive heart failure (or left ventricular systolic dysfunction) | 1 |
| H | Hypertension: blood pressure consistently above 140/90 mmHg (or treated hypertension on medication | 1 |
| A2 | Age ≥ 75 | 2 |
| D | Diabetes Mellitus | 1 |
| S2 | Prior stroke or TIA or thromboembolism | 2 |
| V | Vascular disease (e.g., peripheral artery disease, myocardial infarction, aortic plaque) | 1 |
| A | Age 65–74 years | 1 |
| Sc | Sex category (i.e., female sex) | 1 |
Table 2: Risk predictor for thromboembolic stroke; CHA2DS2-VASc score
Traumatic Brain Injury
Systemic inflammatory response syndrome (SIRS): SIRS is a severe systemic disease that frequently progresses to sepsis. Sepsis is caused by infections such as severe pneumonia or UTI, while SIRS can be caused by infections or severe trauma. A SIRS diagnosis requires two or more of the following: 1) heart rate greater than 90 beats per minute, 2) respiratory rate greater than 20 breaths per minute, 3) temperature less than 96.8°F (36°C) or greater than 100.4°F (38°C), and 4) white blood cell count less than 4,000 cells/mm³ or greater than 12,000 cells/mm³). Early SIRS is common in people with moderate to severe TBI, and the presence of SIRS is associated with decreased heart function that may lead to multi-organ failure, especially of the kidney and lungs. The good news is that SIRS usually resolves on its own within one week, but it’s an important condition to be aware of and to discuss with your doctor.
Everything You Need to Know
After SCI or stroke, you have a significantly increased risk of heart attack or stroke. As a result, you’ll need to make lifestyle changes, such as consuming a healthier diet; getting regular exercise; treating medical problems like hypertension, diabetes, and elevated cholesterol; and if you smoke, quitting.
Traumatic brain injury doesn’t increase your risk of cardiovascular disease, but if prior to or after your injury you had or have any of the risk factors listed below, you are at an increased risk of heart attack or stroke:
• type 2 diabetes
• smoking
• high LDL cholesterol
• a family history of cardiovascular disease
• excess weight or obesity
• lack of regular exercise
• an unhealthy diet
• atrial fibrillation (for stroke only)
Also, many people with ANI have autonomic nervous system (ANS) dysfunction. This manifests most commonly by orthostatic hypotension and fluctuations in blood pressure. After SCI, ANS dysfunction may become life threatening due to autonomic dysreflexia, in which your systolic blood pressure can rise as high as 300 mm Hg, necessitating emergency treatment.
The good news for all of us is that our heart health is primarily determined by our lifestyle and the choices we make on a daily basis. This means you can decrease your risk of heart attack or stroke by modifying your habits. Be sure to reach out for help in any of the areas where you know you need to make changes; your family, friends, and health care team will support you.