Chapter 6: Drugs for Cardiovascular Arrhythmias and Hypertension

Over the past 10 to 12 years great progress has been made in the control of cardiac arrhythmias and hypertensive problems. In 1990 the process for starting cardiopulmonary resuscitation (CPR) began with a "precordial thump"²⁰ Today it begins with early defibrillation. At that time one of the main medications used by physicians during cardiac emergencies was lidocaine to decrease premature ventricular contraction (PVC).²⁰ Today lidocaine is still used, but there are newer antiarrhythmics that may be used preferentially. Additionally, in the early 1990s there was an awakening of the sports medicine community regarding cardiac problems in athletes as a result of the untimely death of Loyola Marymount University (LMU) basketball player Hank Gathers. At the time of his death, Gathers was playing in a basketball game for LMU. The cause of his death was secondary to presumed hypertrophic cardiomyopathy. Other prominent athletes who have died from cardiac causes include basketball player "Pistol Pete" Maravich (abnormal coronary arteries), U.S. Olympic volleyball star Flo Hyman (ruptured aortic aneurysm associated with Marfan's syndrome), running advocate Jim Fixx (heart attack while running), and baseball pitcher Darryl Kile (atherosclerotic coronary artery disease). The athletic trainer must recognize the importance of broadening his or her knowledge base to include technical information, such as cardiovascular conditions, that affect the health and performance of the athlete. After the passing of Hank Gathers, the immediate care given by the athletic trainer was closely analyzed. Why did this unfortunate consequence occur? The inconsistency exhibited by Gathers in taking the proper amount of the prescribed medication at proper intervals was determined to be a contributing factor to his death. The findings from the Hank Gathers case gave athletic trainers the realization that they must help athletes to better understand the importance of following dosage regimens as prescribed. The athletic trainer must now see that a part of his or her role is to help keep athletes on track with their medication regimens, ensuring that dosing occurs in the appropriate amounts and at the proper times.

In the 1980s and 1990s little, if any, information regarding cardiac and hypertension problems in athletes was published. However, if one were to conduct a review of newspaper and sports magazine articles of those decades regarding cardiovascular disorders and sudden cardiac death in athletes, it would become apparent that many of these problems occurred in collegiate and professional sports settings. Based on current knowledge, it is not proper to state that younger players do not experience cardiovascular problems; it is more appropriate to say that these problems do not receive the same publicity as those in the older athlete. Some exercise physiologists and physicians suggest that younger athletes do not stress the cardiovascular system as much as college or professional athletes. For example, high-school athletes may participate in a number of different sports during the school year, with each sport imposing different cardiovascular demands. High-school athletes spend most of their practice time learning skills and strategies, which does not maximally stress the circulatory system, so their cardiovascular challenges are limited compared to those of college or professional athletes. Because a high-school athlete does not have maximal demands on the cardiovascular system, many potential cardiovascular problems typically go undiscovered until the athlete gets to the college, university, or professional level, where the focus of his or her training changes to the total fitness of the cardiovascular system. However, there are documented cases of high-school athletes collapsing during activity because of cardiovascular difficulty. The American College of Cardiology has developed a sports classification system (Table 6–1) so that physicians can recommend what types of sports an athlete with a cardiac condition may participate in safely. Each physician must make his or her own decisions for athletic participation based on the best interest of the athlete.

New information regarding gender differences in sudden cardiac death and arrhythmias suggests that each gender may be more susceptible to certain types of arrhythmic conditions. Women have a lower incidence of sudden cardiac death and men have a higher incidence of atrial fibrillation.²⁴ Additionally, the incidence of arrhythmias is increased in pregnant women. Wolbrette et al. reported that atrial fibrillation is generally more difficult to treat in women.²⁴

Athletes can experience numerous types of cardiac and vascular problems. Because there are so many types of potential cardiovascular problems and medications, we cannot discuss all of them in this chapter. Franklin and Shepard provide a good review article for athletic trainers regarding many different cardiac problems experienced by athletes.⁵

The most prevalent treatable conditions in the athlete are cardiac arrhythmias and hypertension. In this chapter we first discuss the drugs used to treat cardiac arrhythmias, and then move on to drugs that could be prescribed for hypertension in the athlete.

Cardiac arrhythmia is defined in Taber's Cyclopedic Medical Dictionary as "Irregular heart action caused by physiological or pathological disturbances in the discharge of cardiac impulses from the sinoatrial node or their transmission through conductive tissue of the heart."²⁵ Cardiac arrhythmias (Table 6–2) can be a result of many different etiologies from severe electrolyte imbalances to hypertrophic cardiomyopathy and various other disease processes.¹⁷

Cardiac arrhythmias are not considered highly prevalent in the general population because only about 0.4 percent of people, mostly white men, experience atrial fibrillation.⁷ This percentage increases slightly in older populations. Often the medications do not repair or correct the problem or disease process that is occurring in the abnormal heart, but instead control arrhythmias and assist the heart in maintaining a natural rhythm. In recent years, physicians have also controlled cardiac arrhythmias with device-based techniques such as implantable pacemakers or defibrillators.⁸ For the athletic trainer, it would be wise to understand the implications of both treatment options because athletes with arrhythmias may present to the athletic trainer with either of these treatment plans.

Interestingly, arrhythmias may be present and then disappear for unknown reasons.²⁶ This phenomenon can certainly cause problems for the active athlete and the healthcare provider. Arrhythmias can result in syncope, which can be fatal in certain sports such as diving, downhill skiing, and gymnastics. For athletes participating in sports in which a sudden loss of consciousness can result in death, closely monitored drug therapy becomes more significant. Additionally, certain illegal drugs such as cocaine can also cause arrhythmias and result in death, as in the case of in Maryland basketball player and Boston Celtic draftee Len Bias.

Zipes recommends that all athletes with a diagnosed arrhythmia who are deemed fit to participate in athletics should be reevaluated after they have participated in a conditioning program for their sport to determine if any conditioning effects are noted in the athlete's arrhythmia.²⁶ Athletic trainers should also be vigilant in encouraging the athlete to maintain compliance in taking their prescribed medication. Too often athletes think that they are feeling better or want to reduce an adverse effect of a drug by discontinuing its use, leading to potentially lethal consequences.

To understand which drugs are used in differing situations, a basic understanding of the different types of cardiac arrhythmias is necessary. Some of these are benign changes in cardiac rhythm requiring no treatment. Others are life threatening.

Irregular heart rhythms are common in the developing hearts of children and adolescents. Sinus arrhythmia, the most common type, produces changes in heart rate with normal respiration. It requires no treatment.

Irregular beats can occur in the atria or atrioventricular junction (premature atrial contraction [PACs]) or supraventricular premature beats) or from the ventricle (PVCs). The diagnosis of these rhythms cannot be made by simple auscultation; it requires an electrocardiogram.

Premature atrial contractions are usually of little hemodynamic significance and often resolve spontaneously or require no treatment. Occasionally they become more common with caffeine or sympathomimetic medications (e.g, cold-care preparations). Rarely are they associated with structural heart abnormalities. At times, irregular atrial rhythms such as atrial flutter or atrial fibrillation occur in older individuals and may require treatment.

Abnormal rhythms in the ventricles are also common. Some medication treatments may actually worsen ventricular ectopy. Premature ventricular contractions increase with age and may be benign in several instances: (1) isolated contractions, (2) when they are uniform and associated with a normal corrected QT interval, (3) when the cardiac physical examination is normal, (4) when the family history is negative for sudden cardiac death, and (5) when they disappear with exercise.¹¹ A person may feel the heart pound or beat when these extra beats occur. This sensation does not worsen the prognosis, and reassurance can be given.

If the rhythm is determined to be significant by cardiac evaluation and appropriate studies, the cardiologist may recommend antiarrhythmic medication.

The drugs discussed in this chapter as being indicated for cardiac arrhythmias often do not repair cardiac tissue that has fallen into a diseased state, but instead alter the dysfunctional rhythm and allow the heart an improved functional capacity. The medications prescribed for arrhythmia are divided into four basic classifications.

Class I

The sodium channel-blocking drugs are typically divided into three subclassifications. However, for the athletic trainer, it is more important to understand the mechanism of action of this entire classification rather than the technical aspects of how each subclass alters the heart rhythm. The sodium channel blockers inhibit sodium channel activity, which, in turn, retards cell membrane excitability. For a more detailed explanation of the Class I arrhythmic medications, one can read Ciccone or Smith and Reynard.^4,22

Class II

Beta-adrenergic blocking agents make up this class of drugs that work to control arrhythmias by antagonizing the stimulation of the heart via the sympathetic system. The beta blockers were the first antiarrhythmic drugs produced to assist people with tachycardia. Originally, when cardiac responses were determined, they were divided into the "alpha effects," which were excitatory in nature, and the "beta effects," which were inhibitory in nature. The beta blockers come by their name because of their inhibitory role in the control of arrhythmias.

The mechanism of action of these drugs is not clear, but it may involve potassium and sodium exchange. In any event, they stabilize cell membrane excitability to control heart rhythm.

Beta blockers have been used as performance-enhancing aids to control heart rhythm, breathing, and muscular movement in biathlons, riflery, archery, shooting, and synchronized swimming. These agents are banned as performance aids, and the athlete must be aware of the regulations of the relevant sports organizations' governing bodies.

When athletes use beta blockers, they must understand that they may have difficulty in achieving their maximal heart rate. This can affect performance and endurance. Athletes who take beta blockers need to understand the ramifications of reducing their maximum heart rate, which is what happens when they take these drugs as prescribed. Beta blockers do not allow the athlete's heart rate to reach maximum, so the athlete must use a perceived exertion protocol (such as that utilized in the graded treadmill test in exercise physiology laboratories.)

Class III

The drugs in this classification direct their effect by delaying repolarization. They do this by blocking the potassium channels of the cardiac muscle. These drugs may also have an effect on the sympathetic control of the heart rhythm.

Class IV

The drugs in this classification control heart rhythm by slowing the calcium activity of the sinus and atrioventricular (AV) nodes. These drugs slow conduction velocity, mainly at the AV node, and thus slow the heart rate.

Adverse Effects

The recognized and expected adverse effects of this class of drugs are lethargy, fatigue, bradycardia, hypotension (orthostatic), and sometimes a feeling of cold in the extremities. Some people experience additional adverse effects such as rashes, pruritus, headache, nausea, diarrhea, swelling, behavioral disturbances, disorientation, and other problems. If the athlete is experiencing any of these additional adverse effects, he or she should consult his or her physician immediately. Despite their purpose—reducing arrhythmia— one of the most common adverse effects of the anti arrhythmic drugs is an increase in rhythm disturbances. Because they work to control a single type of arrhythmic activity, these drugs can result in other types of cardiac arrhythmias.⁸

Antiarrhythmic Drug Interactions

It appears that there are numerous drug interactions involving antiarrhythmic drugs, and the physician should discuss with the athlete and athletic trainer any drug interactions that can occur. We have organized a short table of drug interactions (Table 6–3) so that the athletic trainer can get an idea of the interaction possibilities with this class of drugs.

Device Therapy

Pacemakers were first implanted in 1958 and since that time have undergone dramatic improvements in design and function. Implantable cardioverter defibrillators (ICDs) were first used in 1980 to control life-threatening ventricular arrhythmias. These, too, have progressed in design and function since inception. In recent years a number of clinical trials were completed demonstrating the effectiveness of both types of devices for control of cardiac arrhythmias.^2,10,21 The athletic trainer should be aware of the types of device therapy available to control cardiac arrhythmias and any precautions to follow to make sure that the athlete is safe as he or she participates in a sport.

The purposes of these devices are to detect the heart rhythm and treat abnormalities. They can be set to treat bradycardia, tachycardia, or ventricular fibrillation by either pacing or synchronized cardioversion.⁹ Implantation can be performed transvenously and no longer requires hospitalization or open-heart surgery. The use of ICDs to prevent sudden cardiac death is currently being evaluated.¹⁶

The ICD is not a common treatment in competitive athletics. In the rare case when an athlete requires an ICD, clearance for participation should be given by the prescribing cardiac electrophysiologist. The athletic trainer will want to discuss with the athlete's physician any special precautions or arrangements that should be made to ensure the safety of the athlete.

Systemic hypertension is the most common cardiovascular condition observed in competitive athletes.¹⁴ For an adult athlete to be diagnosed with hypertension, he or she must have his or her blood pressure measured by sphygmomanometry on at least three separate occasions (Table 6–4). On all three occasions, the systolic readings must be above 140 mm Hg.²⁵

The American Society of Hypertension (ASH) estimates that about 24 percent of the population suffers from hypertension, with women comprising slightly more than 50 percent of the total. The ASH also estimates that over 90 percent of the population suffers from hypertension without an identified cause, a condition also known as "essential hypertension."⁴ In contrast, there is also secondary hypertension, which does have an underlying or diagnosable cause. It develops in fewer than 5 percent of physically active patients and is most commonly related to vascular or parenchymal renal disease.

Blood pressure abnormalities can be subdivided into multiple classifications as outlined in Table 6–5.⁹

Normal blood pressure measurements carry the recommendation of allowing full sports participation if there is no concomitant heart disease.

Prehypertensive measurements mean that the physician is going to have to make a decision based on the signs and symptoms exhibited. In some situations the athlete could have an antihypertensive medication prescribed based on the type of sport he or she is participating in and the intensity of participation. However, if the physician determines the intensity of the sport to be low or the athlete does not have severe symptoms, the athlete may not be required to take any medication to continue participation. There is evidence that exercise can assist with the reduction of mild hypertension, and the athlete may be exercising per his or her physician's orders.

Hypertension, once diagnosed by a physician, is further subdivided into two stages:

• Stage 1 hypertension should be monitored closely by the athlete and the athletic trainer. Be sure to check with the athlete's physician regularly to report any changes in blood pressure measurements in the hypertensive athlete.

• Depending on the physician's examination, testing, and final decision, the athlete with Stage 2 hypertension could be restricted from sports participation requiring a high dynamic output. Once the athlete is on medication and has the hypertension under control, the physician may allow him or her to participate in sports requiring high static capabilities. If the athlete is determined to participate in sports, the athletic trainer must be vigilant in monitoring his or her compliance in taking the medication (Table 6–5).

The athletic trainer or physician should obtain a clinical history of the athlete. This should include inquiring about behaviors that affect blood pressure, such as the use of smoking or chewing tobacco, alcohol or drugs (including OTC stimulants such as caffeine and cold-care medication, diet pills, cocaine, and anabolic steroids), and diet. Specific questions regarding use of salt and intake of high-sodium and high-fat foods should be determined. Additionally, ask the athlete about the use of dietary supplements, particularly ma huang and other supplements containing any amount of ephedra. Increased stress, although difficult to quantify, increases circulating catecholamines and may also be a precursor to high blood pressure.

Nondrug treatment should be initiated after the athlete has been diagnosed with hypertension. These methods include changing the diet to include less processed food and more fruits, vegetables, and fiber. Regular aerobic exercise and weight loss can improve lifestyle and contribute to lower blood pressure. Limiting alcohol use and managing stress by biofeedback or relaxation techniques is also recommended.

Medications for Hypertension

There are several "families" of antihypertensive medications that lower blood pressure. Depending on the clinical case, one family of medication may be more suitable than another. The physician may also elect to use a combination of medications to control hypertension.¹²

Diuretics are drugs with a net effect of promoting salt and water loss, which decreases systemic vascular pressure. This is accomplished by reducing sodium chloride and water reabsorption.

Calcium channel blockers are vasodilators because they block the movement of calcium into smooth muscle cells. Vasodilators inhibit the contractile mechanism of the cells. The blood vessels become less constricted, allowing uninhibited blood flow.

Angiotensin-converting enzyme (ACE) inhibitors act on the renin-angiotensin system. When blood pressure falls, renin is released from the kidneys and joins with angiotensinogen enzyme, released by the liver, to become angiotensin I. A converting enzyme creates angiotensin II, a very potent vasoconstrictor, which results in increased blood pressure. To inhibit this type of blood pressure increase, ACE inhibitors prevent conversion of angiotensin I to angiotensin II.

The newest entrants in this renin-angiotensin strategy are the angiotensin II blockers. These drugs block the angiotensin II receptors at the cellular level, thus stopping the angiotensin II from causing an increase in blood pressure.¹⁵

Beta blockers are medications that inhibit sympathetic activity in the body. They reduce blood pressure by decreasing heart rate, the force of myocardial contraction, and cardiac output. This concomitantly reduces peripheral vascular resistance.

Alpha blockers block alpha-1 adrenergic receptors in the smooth muscles of the peripheral vasculature, which leads to vasodilation and lowering of blood pressure.^3,6

Table 6–6 provides an overview of the general categories of activity that an athlete with hypertension might be able to participate in while being monitored by the physician and athletic trainer. It should always be remembered that athletes with hypertension must be checked and rechecked regularly to be sure their medication is controlling their known cardiovascular problem.

Adverse Effects

There are potential adverse effects with all of these classes of antihypertensive medications. Diuretics may lead to fluid depletion, which in turn leads to dehydration, orthostatic hypotension, or electrolyte imbalances. Orthostatic hypotension can be the result of fluid depletion, so the athletic trainer should continually remind athletes taking diuretics—and, for that matter, all athletes— to rehydrate when losing a great deal of water volume during activity. ACE inhibitors often cause an annoying dry cough, which may lead to their discontinuance. Beta blockers may significantly decrease heart rate, leading to bradycardia, dizziness, or fatigue. Another common adverse effect is bronchoconstriction. Therefore beta blockers should be used with caution in asthmatics. Alpha blockers can cause reflex tachycardia or orthostatic hypotension.

The story of Hank Gathers is much like the above situation. Hank Gathers suffered from an abnormal heart rate and was put on medication to control the heart rhythm. He had been experimenting with his medication dosage because the dosage prescribed by his physician was causing lethargy and other adverse effects that he did not like and that prevented him, he thought, from performing at his top level. In the video of his last basketball game, it is apparent that he was playing with a decreased cardiac output, as evidenced by his stumbling and weaving as he tried to run down the basketball court. His last minutes played out in severe circulatory distress as he collapsed in the middle of the court. Unfortunately, neither the athletic trainer who was summoned nor the emergency services provided could save his life.

1. It is possible for an athlete taking medication for a cardiac arrhythmia to experience increased arrhythmias.

   True    False

2. How many categories of antiarrhythmia drugs were discussed in this chapter?

   1. 1

   2. 2

   3. 3

   4. 4

3. Beta blocker medication can be prescribed by a physician for which of the following disorders?

   1. Hypertension and inflammation

   2. Arrhythmias and balance disorders

   3. Hypertension and arrhythmias

   4. Inflammation and arrhythmias

4. Implantable devices are now more commonly used to control which disorder?

   1. Cardiac arrhythmias

   2. Respiratory dysfunction

   3. Balance disorders

   4. Joint inflammation

5. Hypertension is divided into multiple categories in this chapter. Which activity is contraindicated in all categories?

   1. Collision sports

   2. Isotonics

   3. Plyometrics

   4. Isometrics

6. Athletes who are fit and competing at high levels will not experience hypertension.

   True    False

7. An athlete must be referred to a physician when the athlete's blood pressure reading reaches which of the following measurements:

   1. 135/85

   2. 140/90

   3. 120/80

   4. 125/85

8. Diuretics are usually prescribed by a physician for which of the following disorders?

   1. Hypertension

   2. Inflammation

   3. Weight loss

   4. Asthma

9. Sinus tachycardia is generally defined as which of the following:

   1. Greater than 80 beats per minute

   2. Greater than 90 beats per minute

   3. Greater than 100 beats per minute

   4. Greater than 200 beats per minute

10. Sinus bradycardia is generally defined as which of the following?

    1. Less than 70 beats per minute

    2. Less than 60 beats per minute

    3. Less than 50 beats per minute

    4. Less than 40 beats per minute