Fatigue—Can It Be Due To Cardiac Malfunction?
Abstract & Commentary
By Harold L. Karpman, MD, FACC, FACP
Dr. Karpman is Clinical Professor of Medicine, UCLA School of Medicine
Dr. Karpman reports no financial relationships related to this field of study.
This article originally appeared in the July 29, 2008 issue of Internal Medicine Alert.
Synopsis: Complaints of fatigue were not associated with changes in blood pressure or heart rate but were significantly associated with decreased cardiac index and stroke index even after controlling for demographic variables and depressive symptoms.
Source: Neleson R, et al. Arch Inter Med. 2008;168(9): 943-948.
Fatigue is one of the most commonly encountered complaints in medical practice, especially in the elderly. It is frequently accompanied by a decreased capacity or motivation for work activities and by feelings of weariness and sleepiness. It is a non-specific symptom commonly associated with medical conditions such as obstructive sleep apnea, hypothyroidism, anemia, infections, renal or hepatic disease, heart failure, severe stress, chronic fatigue syndrome and/or a variety of other medical or surgical conditions. Patients with severe chronic fatigue syndrome have been shown to have significantly lower stroke volumes (SV) and cardiac output (CO) than the control patients.3,4 Individuals who reported more sleepiness were found to have lower CO and significantly lower SVs and, furthermore, increased sleepiness has even been found to be related to decreased CO in a sample of patients with obstructive sleep apnea but without known cardiac disease.5
Because fatigue occurs with and without other symptoms which have been demonstrated to be associated with hemodynamic cardiovascular malfunction, Neleson and his colleagues mounted a study to examine the relationship between self-reported fatigue and hemodynamic functioning at rest and in response to a stressor (ie, public speaking) in healthy individuals.10 Heart rate, SV, and CO were measured using impedance plethysmography in a total of 142 individuals at rest and during a speaking stressor. SV and CO were converted to stroke index (SI) and cardiac index (CI) by adjusting for body surface area. Those study participants complaining of excessive fatigue demonstrated lower SI and CI levels than did individuals with moderate and minimal fatigue both at rest and in response to the speaking stressor, suggesting that the fatigue may have been, at least in part, secondary to hemodynamic cardiovascular abnormalities even in ostensibly healthy individuals.
Commentary
Subtle hemodynamic changes in SI and CI had been noted to occur in veterans with Gulf War Syndrome and even in reasonably healthy individuals who complain of chronic fatigue.3,4,6-9 These findings suggest that fatigue is often associated with a weak but measurable relationship with cardiac malfunction as determined objectively by altered measurements of CI and SI. However, simple office measurements such as heart rate or blood pressure are rarely significantly altered only by fatigue and, therefore, these simple measurements on the usual office patient are rarely abnormal enough to explain significant fatigue in that patient. The results of the Neleson study10 should be interpreted with caution because of the small number of patients in the trial and because impedance cardiography tends to underestimate the true SI and CI; in fact, other techniques such as echocardiography should be considered for any future studies which may be mounted to evaluate hemodynamic abnormalities associated with complaints of fatigue.
In summary, the results of the Neleson study10 suggest that decreased hemodynamic functioning (ie, decreased CI and SI) may be related to complaints of fatigue at rest and during acute stress even in apparently healthy subjects. It should be recognized that the effects of fatigue and/or stress on cardiovascular functioning as observed in this study may even be more significant in patients with known cardiovascular disease (ie, for example, some studies suggest that excessive fatigue may be an early manifestation of heart failure1, 2) and therefore, the abnormal hemodynamic effects observed in patients with fatigue may also explain the beneficial response observed to occur on both cardiovascular conditioning and on symptoms of fatigue with exercise.11,12 Because so many studies have demonstrated the solid benefits of regular exercise in cardiac patients, it would seem that there would be little to lose by extending the benefits of exercise to healthy individuals as well as to cardiovascular patients complaining of fatigue since hemodynamic abnormalities secondary to fatigue may be at least partially responsible for the fatigue in both groups of patients.
References
- Dworkin HJ, et al. Abnormal left ventricular myocardial dynamics in 11 patients with chronic fatigue syndrome. Clin Nucl Med. 1994;19(8):675-677.
- Lerner, et al. A small, randomized, placebo-controlled trial of the use of antiviral therapy for patients with chronic fatigue syndrome. Clin Infect Dis. 2001;32 (11):1657-1658.
- Peckerman A, et al. Abnormal impedance cardiography predicts symptom severity in chronic fatigue syndrome. Am J Med SCI. 2003;326(2):55-60.
- Peckerman A, et al. Cardiovascular stress responses and their relation to symptoms in Gulf War veterans with fatiguing illness. Psychosom Med. 2000;52(4):519.
- Choi JB, et al. Sleepiness in obstructive sleep apnea: a harbinger of impaired cardiac function? Sleep. 2006; 29(12):1531-1536.
- Cook DB, et al. Perceived exertion in fatiguing illness: Gulf War veterans with chronic fatigue syndrome. Med Sci Sports Excer. 2003;35(4):569-574.
- Cook DB, et al. Perceived exertion in fatiguing illness: civilians with chronic fatigue syndrome. Med Sci Science Excer. 2003;35(4)563-568.
- Nagelkirk PR, et al. Aerobic capacity of Gulf War veterans with chronic fatigue syndrome. Mil Med. 2003; 168(9):750-755.
- Nelson JJ, et al. Medical follow-up of Persian Gulf War veterans with severe medically unexplained fatigue: a preliminary study. Mil Med. 2001;166(12):1107-1109.
- Neleson R, et al. The relationship between fatigue and cardiac functioning. Arch Inter Med. 2008;168(9):943-948.
- O'Connor PJ, et al. Chronic physical activity and feelings of energy and fatigue. Med Sci Sports Exerc. 2005;37(2):299-305.
- Puetz TW, et al. Effects of chronic exercise on feelings of energy and fatigue: a quantitative synthesis. Psychol Bull. 2006;132(6):866-876.
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