Running with Heart

by Dr. Anne G Evans, MBA

Although regular aerobic exercise, including running, is consistent with excellent cardiovascular health there are cardiac disorders that may afflict runners. As with Bob Lafferty (see below) cardiac disorders are not always readily detected and can be masked by existing non-cardiac disease. My father, another example, was fit, ate healthfully and exercised daily. At 52, he returned from his usual morning run-and died of a heart attack.

What cardiac disorders can runners experience? What are their warning signs? What precautionary measures should be taken by even the fittest? This article provides an introduction to some of the cardiac disorders that can threaten the fitness runner.

Cardiac Disorders Every Runner Should Know About
Understanding cardiac disorders relevant to runners requires learning some medical jargon. Some of the basic terms are explained below.(1)

Arrhythmia - an irregular heart beat
The heart muscle's chambers (two atrial and two ventricular) normally beat in a coordinated sequence driven by inherent electrical activation. The beat represents the chambers' orderly contraction and relaxation, which pumps blood through the body. Electrical activation originates from the sinoatrial node within the heart wall, spreads through the atria initiating atrial contraction, then through the ventricles causing ventricular contraction. During relaxation the heart refills with blood in preparation for the next beat. Any distortion of this regular (sinus) rhythm is an arrhythmia. Specific examples of arrhythmias include atrial ectopic beats, ventricular fibrillation, bundle branch block and intraventricular conduction defects.

Bradycardia - a slow heart beat, i.e., under 60 beats per minute (bpm)
A slow, regular heart rate is characteristic of a healthy, conditioned heart. The beat slows as cardiac volume, mass and output increase-meaning that the heart's pumping efficiency is improved. It does not need to beat as fast to circulate the same blood volume as an unconditioned heart. Resting bradycardia is one component of the normal adaptations occurring in persons who regularly perform endurance training-a condition termed Athletic Heart Syndrome.

Tachycardia - a rapid heart beat, i.e., over 100 bpm
The immediate cardiac response to exercise generally includes a regular tachycardia because of the need for greater oxygen delivery to tissues. This increase is relatively less in a conditioned heart as compared to an unconditioned heart.

Coronary Arteries - vessels that supply blood to the heart muscle
Most Coronary Artery Disease (CAD) is due to insidious build-up of deposits within the coronary arteries (Coronary Atherosclerosis) that abruptly disrupts blood flow to the heart muscle. Compromised blood flow can cause sudden loss of heart function (Cardiac Arrest) and death (Sudden Cardiac Death). Atherosclerosis-the process by which fats, cholesterol, calcium and other substances accumulate in a vessel's lining-can occur in any artery. Risk factors include poor physical fitness, hypercholesterolemia (high cholesterol) and high triglyceride blood levels-not a problem for most runners.

Other less common forms of CAD may affect runners. Coronary Artery Spasm can occur in a normal coronary artery without apparent cause (idiopathic) and reduce or stop the blood flow to a part of the heart. Coronary Artery Anomaly (CAA) is a malformation present from birth (congenital) in which the coronary artery grows on the wrong side of the heart, often between the pulmonary artery and the aorta.(4) During exercise, both the pulmonary and aorta dilate. In an athlete with CAA, dilation can squeeze the coronary artery blocking blood flow and causing sudden death.

Heart Murmur - an abnormal heart sound
Heart valve defects are the most common cause of heart murmurs-either valves between the heart chambers (e.g., Mitral Valve Disease) or valves in the vessels leading to/from the heart (e.g., Aortic Valve Disease). Less common causes include holes in the wall (Septum) between heart chambers (e.g., Atrial or Ventricular Septal Defect). Murmurs can be acquired (e.g., after severe fever) or congenital (e.g., septal defects). Depending on the underlying cause and severity, heart murmurs can have different sounds, intensity and timing within the beat. The abnormal sounds result from aberrant blood flow as the heart pumps. As example, in Mitral Insufficiency blood leaks backward through the mitral valves, which separate the left ventricle from the left atrium. The structural defect underlying a murmur compromises the heart's efficiency-it must work harder to circulate blood. With time, heart enlargement, changes in blood pressure, arrhythmias and cardiac failure can occur.

Warning Signs
Symptoms of cardiac disorders can be insidious, vague, non-specific-even absent! Any of the following should raise concern meriting professional medical evaluation. (2,3,4)

• Familial history of cardiac disease.
• Recurrent fatigue, weakness, dizziness, disorientation, difficult (dyspnea) or uncomfortable (orthopnea) breathing, and/or chest pain-particularly during exercise.
• Severe, constricting chest pain (angina pectoris).
• Cold or blue (cyanotic) skin and/or persistent fluid retention (edema).
• Irregular pulse, sensation of pulsation in the neck, and/or neck vein (jugular) distention.
• Loss of consciousness (syncope).

Precautionary Measures
Even if you feel healthy, the following practices may save your life:

• Know whether your family has history of cardiac disorders.
• Obtain a general physical exam annually, ideally including an electrocardiogram (ECG) and chest x-ray. Ask the physician for your heart rate, blood pressures and lipid profile.
• Learn how to take your pulse and check it during exercise for rate and regularity. Exercise within your heart rate target training zone.(5)
• Maintain a health and exercise diary including corresponding environmental factors. If your health falters, this record will be your and your physician's optimal first-line diagnostic tool.

In Closing...
Even the fittest runners can be vulnerable to heart conditions. Therefore, it is important to exercise common sense as well as to listen to your body. Be aware of threats to your physical well being, without being paranoid, and proactively evaluate your susceptibility, without being obsessive. Indeed, "an ounce of prevention is worth a pound of cure."

Dr. Anne G. Evans, MBA has been a health professional for 25 years and a runner for 30. Contact Anne at agevansevansassoc.net or 858-729-0115.

Runner Closeup:
Running with a Pacemaker
An RAC member for 13 years, Bob Lafferty, now 70, has been running most of his life despite nearly 40 years of asthma and allergies. In 1999, his allergies appeared to worsen. When he ran his chest tightened; he also became dizzy and breathless. About 30 minutes into his run, symptoms resolved although fatigue set in. Lafferty sought medical assistance-repeatedly. Three specialists told him he was experiencing exercise-induced asthmatic bronchiospasm and prescribed medications without benefit. Persistence paid off, however. A fourth specialist suspected cardiac disease. Treadmill stress testing and 48-hour cardiac Holter monitoring revealed an abnormally slow, irregular heart rate.

On March 27, 2003, a cardiac pacemaker was surgically placed inside Lafferty's chest to correct the disorder. He resumed running two weeks later, hardly skipping a beat in his training program. Lafferty now looks forward to becoming a marathoner.

References

1. Stedman, T.L. (2000). Stedman's medical dictionary (27th ed.). Baltimore : Lippincott Williams & Wilkins.
2. Beers, M.H., & Berkow, R.(Eds.) (1999). Merck manual diagnosis & therapy (17th ed.). Whitehouse Station : Merck & Co. Available web site.
3. American Heart Association (2003). Heart and stroke facts [Booklet]. Available web site.
4. Swint, S. (2000, May 1). Sudden death in athletes may sometimes be prevented. WebMD Medical News Archive. Available web site.
5. National Center for Chronic Disease Prevention and Health Promotion. Nutrition & Physical Activity. (2003, Feb 6). Target heart Rate and estimated maximum heart rate. Available web site.