Athlete's Heart Syndrome

Athlete's Heart Syndrome (AHS), also known as hypertrophic cardiomyopathy, is an enlargement of the left side of the heart that occurs in many athletes who participate in intense and competitive athletic training. Due to an excessive amount of aerobic exercise, the heart, like any other muscle in the body, grows larger over time. However, once training subsides, the heart will return to its normal size, which is a key characteristic of Athlete’s Heart Syndrome. If non-athletes experience the same changes, they may be at an increased risk for heart disease and other heart-related problems. An enlarged heart also causes a lower resting pulse in the patient [3] .

History

AHS was first discovered in the 19th century by S. Henschen. He compared the heart size of cross-country skiers to those who lived sedentary lives. He noticed that those who participated in competitive sports displayed symptoms of Athlete’s Heart Syndrome. Henschen believed the symptoms were a normal adjustment to exercise and felt there was no need for concern [3] . Henschen believed that the entire heart became enlarged when in fact it is only the left side that becomes hypertrophic. He also believed athletes with AHS lived shorter lives than those who did not acquire the syndrome. Because his research occurred throughout the 19th century, technology was limited and it became difficult to come up with appropriate ways to measure the hearts of athletes. Few believed in Henschen’s theory about athletes having larger hearts than those who did not participate in sports. Today, Henschen’s original theory has proved to be correct [4] .

Causes and Symptoms

The heart becomes enlarged, or hypertrophic, due to intense cardiovascular workouts, creating an increase in stroke volume, an enlarged left ventricle, and a decrease in resting pulse along with irregular rhythms. The wall of the left ventricle increases in size by about 15-20% of its normal capacity. The left ventricle also decreases in diastolic volume by about 10%. The patient may also experience an irregular heartbeat and a resting pulse between 40-60 beats per minute, also known as bradycardia [3] .

The level of physical activity in a person determines what physiological changes the heart makes. There are two types of exercise: static (strength-training) and dynamic (endurance-training). Static exercise consists of weight lifting and is mostly anaerobic, meaning the body does not rely on oxygen for performance. It also moderately increases heart rate and stroke volume. Dynamic exercises are running, swimming, skiing, and cycling, which rely on oxygen from the body. This type of exercise also increases both heart rate and stroke volume in the heart. Both static and dynamic exercises involve the thickening of the left ventricular wall due to increased cardiac output, which leads to physiologic hypertrophy of the heart. It has been shown that once athletes stop training, the heart returns to its normal size [2] [3] .

Another sign of Athlete’s Heart Syndrome is an S3 gallup, which can be heard through a stethoscope. This sound can be heard as an irregularly shaped heart is filling with blood. The diastolic pressure creates a disordered flow of blood into the heart. However, if an S4 gallup is heard, the patient should be given immediate attention. An S4 gallup is a stronger and louder sound created by the heart if it is diseased in some way. It is typically a sign that there is a serious heart condition present in the athlete [1] .

Detection and Screening

Physicians screen competitive athletes for AHS with a comprehensive five-step evaluation. First, the doctor will ask for a thorough medical history of the patient. In doing so, any information attained will help the doctor decipher if the patient is predisposed for any other heart conditions or if it is actually AHS. Then, the doctor will perform a physical exam, followed by an electrocardiogram (ECG), which shows ventricular wall thickening and also systolic and diastolic pressure. A chest x-ray can also be used to detect changes in the size of the heart. Echocardiograms or exercise treadmill tests can also be used to screen for problems. The patient’s resting pulse and blood pressure should also be monitored. It is recommended that competitive athletes be evaluated using this process every two years [2] [3] .

Is it Dangerous?

It has been thought that AHS is not dangerous once detected. However, it may become an issue if the patient experiences light-headedness, chest pains, or temporary loss of consciousness. If the signs and symptoms of AHS are seen in a sedentary person, it may be a sign of an underlying heart condition. However, the syndrome is not necessarily a health risk if detected in athletes; it is simply a normal physiological adjustment to exercise and training. If an athlete is diagnosed with Athlete’s Heart Syndrome, the athlete must be carefully monitored by a physician to prevent any further complications and to make sure the symptoms do not worsen [3] .

References

1. Moses, S., (2008) Athletic Heart Syndrome. Family Practice Notebook. http://www.fpnotebook.com/Sports/CV/AthltcHrtSndrm.htm.

2. Pelliccia, A., Di Paolo, F.M., Maron, B.J. (2002) The Athlete’s Heart: Remodeling, electrocardiogram and preparticipation screening. Cardiol Rev. 10:85-90.

3. Rich, B.S., Havens, B.A. (2004) The Athletic Heart Syndrome. Curr Sports Med Rep. 3:84-8.

4. Rost, R. (1997) The Athlete’s Heart Historical Perspectives- Solved and Unsolved Problem. Cardiology Clinics. 15:493-512.