Atrial Fibrillation: Definition, symptoms and effects of exercise
By Shelly Malan
Posted on 21 February 2012
To understand what atrial fibrillation is, you need to understand the make-up of the heart.
The heart is divided into four chambers. The two upper chambers are called the atriums. Blood enters the heart through these chambers. From the atrium, the blood gets pumped into the two chambers at the bottom called the ventricles. The ventricles have very muscular walls, which are used to pump blood from the heart to the body when they contract.
In order for the heart to contract, an electrical charge is released which spreads from the right atrium all the way down to the left ventricle. If this electrical discharge of the atrium becomes disorganised, and leads to rapid and irregular ventricular contractions, this is known as a characteristic of atrial fibrillation (AF) (Durstine et al., 2009).
Chronic heart failure, cardiomyopathy, significant valvular disease, coronary artery disease, hypertension, and hyperthyroidism are conditions associated with AF (Durstine et al., 2009). However AF can be found in individuals without any evidence of heart or systemic disease. This is a condition known as ‘lone AF’ (Natell, 2002). Interestingly it is found more commonly in active rather than sedentary males because of their increased left ventricular size (Grimsmo et al., 2009). Predictors of lone AF include (Grimsmo et al., 2009):
The onset of AF in patients with congestive heart failure increases by six fold, and is associated with clinical hemodynamic deterioration. It may predispose patients to systemic Thromboembolisms. (Yamada et al., 2000).
- Atrial ectopic beat: an irregular beat of the heart.
- Changes in electrolytes.
- Atrial enlargement with dilatation and fibrosis.
- Increased vagal tone. The vagal tone is the “slowing down” effect on the heartbeat when stimulated by the vagal nerve.
- Bradycardia: excessively slow heartbeat.
Individuals at risk for developing AF are those with (Benjamin et al., 1994):
Men show a 1.5 times greater likelihood of developing AF than women.
- Old age (incidence of AF approximately doubled for every 10 years increment).
- Diabetes mellitus.
- Left ventricular hypertrophy: enlargement of the left ventricle.
- Hypertension: high blood pressure.
- Myocardial infarction: heart attacks.
- Congestive heart failure.
- Valvular heart disease.
Symptoms of AF
Symptoms occur more frequently with increasing age, and may have the following assorted problems according to Durstine et al., (2009):
- Increased risk of thromboembolic events.
- Rapid ventricular rates.
- Incomplete filling of the ventricles which leads to decreased amount of blood pumped out of the heart and to the body.
- Decreased exercise capacity.
Symptoms of increased heart rate must also be included (Nieuwlaat, 2005):
- Palpations: when a person can feel and abnormal heart beat, for example a fluttering sensation.
- Lassitude: weakness or lack of energy.
- Shortness of breath.
- Symptoms of heart failure in patients with heart disease.
Research by Yamada et al., (2000) includes the following symptoms of AF:
- Abnormal P-wave signal-averaged electrocardiogram (PACCG).
- Frequent premature atrial beat.
- Larger left atrial dimensions.
According to Hampton (2008), AF shows the following characteristics on an ECG:
- Irregular base line
- Irregular QRS complexes, rate varying between 75 and 190/min
- Narrow QRS complexes of normal shape
- Depressed ST segments in leads V5-V6
- Normal T waves
Effects of Exercise Training on AF
Although there is limited scientific research on the effects of exercise on AF, Durstine et al., (2009) suggest that individuals are not expected to have adaptations different to those with normal sinus rhythms. Complications may arise with individuals who have underlying heart disease. Importantly, exercising in groups provides social activity for older individuals. This plays a vital role in improving quality of life (Flynn et al., 2009).
Hegbom et al., (2007) conducted a study “The effects of exercise on AF”. They stated that management of AF requires the improvement of symptoms which they identified as:
- Exercise intolerance,
- Effort dyspnoea,
- Rest dyspnoea,
- Chest discomfort/pain,
- Blurred vision.
Their study showed that most symptoms tend towards improvement after physical training, with significant improvement in tiredness/lack of energy and shortness of breath. As patients become more tolerant to exercise exertion, they experienced less fatigue and dyspnoea and became more comfortable performing tasks of daily living. This improved physical health resulted in improved feeling of well-being (Hegbom et al., 2007).
The hypothesis that regular moderate physical exercise might decrease the ventricular rate during rest and exercise, in patients with chronic permanent AF, and consequently improve exercise capacity and quality of life, had the following results (Plisiene et al., 2008).
After four months of regular exercise:
After two months of regular exercise:
- Ventricular rate during AF at rest significantly decreased from 87 +/- 18 to 78 +/- 15 beats per minute.
- Ventricular rate at maximum exercise decreased significantly.
They concluded that regular moderate physical activity resulted in a 12% decrease in mean ventricular rate in these patients, as well as reducing heart rate during exercise by 8%. However this was a pilot study so a larger control study must be done to provide more validity to these results. (Plisiene et al., 2008).
- An increase of running speed.
- Exercise capacity estimates showed significant improvements, people felt less tired while exercising at the same level. This was done using the BORG scale.
Durstine, J.L., Moore, G.E., Painter, P.L., Roberts, S.O. 2009. ACSM’s exercise management for persons with chronic diseases and disabilities. Third Edition. American college of sport medicine. United States of America
Benjamin, E.J., Levy, D., Vaziri, S.M., D’Agostino, R.B., Belanger, A.J., Wolf, P.A. 1994. Independent risk factors for atrial fibrillation in a population based cohort. JAMA. 271:840-844
Flynn, K.E., Pina, I.L., Whellan, D.J., Lin, L., Blumenthal, J.A., Ellis, S.J., Fine, L.J., Howlett, J.G., Keteyian, S.J., Kitzman, D.W., Kraus, W.E., Houston Miller, N., Schulman, K.A., Spertus, J.A., O’Connor, C.M., Weinfurt, K.P. 2009. Effects of exercise training on health status in patients with chronic heart failure.The Journal of the American Medical Association. 301(14):1451-1459
Fuster, V., Rydén, L.E., Asinger, R.W., Cannom, D.S. Parkhomenko, A., Sigmund Silber, S., Torbicki, A., Blomström-Lundqvist, de Backer, G., Flather, M., Hradec, J., Oto, A., Smith, S.C., Jr., Klein, W.W., Alonso-Garcia, A., Fuster, C., Gregoratos, G., Hiratzka, L.F., Jacobs, A.K., Russell, R.O., Gibbons, R.J.,. Antman, E.M., Alpert, J.S. Faxon, D.P., Lévy, V., McNamara, R.L., Prystowsky, E.N., L. Wann, S., D. Wyse, G., Crijns, H.J., Frye, R.L., Halperin, J.L., Neal Kay, G.N., Werner W. Klein. 2001. ACC/AHA/ESC guidelines for management of patients with atrial fibrillation: executive summary report of the American College of Cardiology/American Heart Association task force on practice guidelines and the European Society of cardiology committee for practice guidelines and policy conferences (committee to develop guidelines for the management of patients with atrial fibrillation) developed in collaboration with the North American Society of pacing and electrophysiology. Circulation: Journal of the American Heart Association. 104: 2118-2150
Grimsmo, J., Grundvold, I., Maehulm, S., Arnesen, H. 2010. High prevalence of atrial fibrillation in long-term endurance cross-country skiers: echocardiographic findings and possible predictors- a 28-30 year follow-up study. Journal of Cardiovascular Prevention and Rehabilitation. 17:100-105
Hegbom, F., Stavem, K., Sire, S., Heldal, M., Orning, O.M., Gjesdal, K. 2007. Effect of short-term exercise training on symptoms and quality of life in patients with chronic atrial fibrillation.Norway International Journal of Cardiology. 116:86-92
Plisiene, J., Blumberg, A., Haager, G., Knackstedt, C., Latsch, J., Norra, C., M. Arndt, M., Tuerk, S., Heussen, N., Kelm, M., Predel, H.G., Schauerte, P.2008. Moderate physical exercise: a simplified approach for ventricular rate control in older patients with atrial fibrillation. Clinical research in Cardiology. 97(11):820-825
Yamada, T., Fukunami, M., Shimonagata, T., Kumagai, K., Ogaita, H., Asano, Y., Hirata, A., Hori, M., Hozi, N. 2000.Prediction of Paroxymal atrial fibrillation in patients with congestive heart failure.Journal of American College of Cardiology. 35:2 405-413