Small heart syndrome

Small heart syndrome
Other namesSmall heart; Neurocirculatory asthenia
SpecialtyCardiology

Small heart syndrome is a cardiovascular condition in which the heart is small and cardiac output is low.[1][2][3][4] It has been defined as a small heart shadow on chest roentgenogram and more specifically as a cardiothoracic ratio (CTR) of less than or equal to 42%.[5][2][3] It has been hypothesized that a small heart in relation to body size may be inadequate for work and that the condition may result in cerebral hypoperfusion, orthostatic intolerance, and exaggerated sympathetic activation.[1][2][3][4] This in turn may result in a variety of symptoms including malaise, weakness, fatigue, tachycardia, heart palpitations, low blood pressure, chest pain, dizziness, shortness of breath, nervousness, trembling, sweating, fainting, and cold feet, among others.[1][2][3][6][4]

The symptoms of small heart syndrome show some parallels to those of chronic heart failure and resemble the symptoms of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).[1][2] Small heart syndrome is known to be present at high rates in people with ME/CFS.[5][7][1][8] General cardiovascular findings in these individuals have included small hearts, left ventricular dysfunction, poor cardiac performance, low stroke volume, low cardiac output, low total blood volume, low blood pressure, cerebral hypoperfusion, and heart rate abnormalities.[5][8][9][10] Exaggerated diurnal variation in blood pressure has also been observed, and diurnal blood pressure variation has been found to correlate with fatigue severity.[8][11] In addition to ME/CFS, people with postural orthostatic tachycardia syndrome (POTS) frequently show small hearts.[7][12] ME/CFS and POTS additionally co-occur at high rates.[1][7][12] Small heart syndrome has been associated with symptoms and their severity in people with ME/CFS.[5][1][2]

Dehydration, for instance due to inadequate fluid intake, diarrhea, or sweating, may worsen symptoms of small heart syndrome due to reduced venous return and cardiac output.[1] Relatedly, adequate hydration in people with ME/CFS may be beneficial.[13] Habitual exercise may improve cardiac and pulmonary conditioning, increase cardiac output, and thereby improve symptoms in the condition.[1] Treatments like antihypotensive agents such as the α1-adrenergic receptor agonist phenylephrine and medications to increase fluid retention and thus blood volume like the mineralocorticoid fludrocortisone may be helpful in small heart syndrome.[1] Compression stockings may increase venous return and improve symptoms as well.[1]

Small heart syndrome in for instance ME/CFS may in part be related to physical inactivity, prolonged bed rest, and associated cardiac deconditioning.[13][5] Alternatively, cardiovascular dysfunction and other symptoms in ME/CFS may not be due to deconditioning and may instead be related to autonomic dysfunction, for example caused by viral infection.[14][15][5] However, even if not a major cause, small heart syndrome may still contribute to symptom burden in ME/CFS.[5] There is said to be no organic heart disease or systemic disease in small heart syndrome.[1] Small heart syndrome due to anorexia nervosa has been reported and may also occur in other situations such as cancer-induced cachexia.[16][17]

The concept of small heart syndrome was first described by René Laennec in 1826.[1][2][18] Subsequently, Commander A. M. Master described small heart as the cause of a condition he referred to as "neurocirculatory asthenia", considered to be synonymous with small heart syndrome, in 1944.[1][2][4] Kunihisa Miwa and colleagues described small heart syndrome as a possible cause or contributor to ME/CFS in 2008 and thereafter.[1][2][3][6][19] Small heart syndrome as a contributor to ME/CFS has also since been studied by Julia Newton and colleagues.[20][21][22]

See also

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Miwa, Kunihisa (15 February 2012). "Small Heart as a Constitutive Factor Predisposing to Chronic Fatigue Syndrome" (PDF). In Snell, Christopher R. (ed.). An International Perspective on the Future of Research in Chronic Fatigue Syndrome. Rijeka, Croatia: IntechOpen. pp. 81–104. ISBN 978-953-51-0072-0.
  2. 1 2 3 4 5 6 7 8 9 Miwa K, Fujita M (July 2008). "Small heart syndrome in patients with chronic fatigue syndrome". Clin Cardiol. 31 (7): 328–333. doi:10.1002/clc.20227. PMC 6653127. PMID 18636530.
  3. 1 2 3 4 5 Miwa K, Fujita M (January 2011). "Is small heart syndrome a "heart" disease or low output syndrome?". Int J Cardiol. 146 (1): 95–96. doi:10.1016/j.ijcard.2010.05.053. PMID 21074872.
  4. 1 2 3 4 Master, Commander A.M. (1944). "Neurocirculatory Asthenia Due to a Small Heart". Medical Clinics of North America. 28 (3): 577–588. doi:10.1016/S0025-7125(16)36376-3. Retrieved 6 April 2026.
  5. 1 2 3 4 5 6 7 Natelson BH, Brunjes DL, Mancini D (September 2021). "Chronic Fatigue Syndrome and Cardiovascular Disease: JACC State-of-the-Art Review". J Am Coll Cardiol. 78 (10): 1056–1067. doi:10.1016/j.jacc.2021.06.045. PMID 34474739. Patients with ME/CFS typically have small hearts, low stroke volume, and low total blood volume, and some have OI. [...] One possible explanation for the reduced ventricular wall mass in ME/CFS may be caused by overall heart size. Indeed, 61% of a group of Japanese ME/CFS patients were reported to fulfill an operational definition of small heart size—calculated cardiothoracic ratios ≤42% from A-P view of chest x-ray. Mitral valve prolapse was identified by echocardiography in 29% of those with small hearts compared with 0% in patients whose cardiothoracic ratio exceeded 42% (18). Cardiological evaluation of these patients found abnormalities: first, about one-third of patients reported dyspnea on exertion or chest pain; one-fifth had ECG evidence of right axis deviation including vertical axis (electrical axis 90°); and they had significantly reduced stroke volume and cardiac indexes compared with healthy control subjects (19). Some of these patients showed clinical improvement, at which time follow-up evaluation showed larger heart size and improved stroke volume/cardiac output; the obvious inference was a relation between cardiac dysfunction and illness severity (20).
  6. 1 2 Miwa K, Fujita M (2009). "Cardiovascular dysfunction with low cardiac output due to a small heart in patients with chronic fatigue syndrome". Intern Med. 48 (21): 1849–1854. doi:10.2169/internalmedicine.48.2347. PMID 19881233.
  7. 1 2 3 Bryarly M, Phillips LT, Fu Q, Vernino S, Levine BD (March 2019). "Postural Orthostatic Tachycardia Syndrome: JACC Focus Seminar". J Am Coll Cardiol. 73 (10): 1207–1228. doi:10.1016/j.jacc.2018.11.059. PMID 30871704. CHRONIC FATIGUE AND FIBROMYALGIA. Chronic fatigue syndrome (CFS) and fibromyalgia are comorbidities frequently associated with POTS. Chronic fatigue has been cited in up to 48% of POTS patients (6), and patients with CFS often have POTS as well (81). Not surprisingly, both POTS and CFS patients share many of the same characteristics including small hearts (81) and lab markers of excessive sympathetic activation; as such, they may exist along the same clinical spectrum (82). Furthermore, chronic fatigue and fibromyalgia often lead to a reduction in physical activity, subsequent deconditioning, and exacerbation of orthostatic intolerance.
  8. 1 2 3 Carruthers BM, van de Sande MI, De Meirleir KL, Klimas NG, Broderick G, Mitchell T, Staines D, Powles AC, Speight N, Vallings R, Bateman L, Baumgarten-Austrheim B, Bell DS, Carlo-Stella N, Chia J, Darragh A, Jo D, Lewis D, Light AR, Marshall-Gradisnik S, Mena I, Mikovits JA, Miwa K, Murovska M, Pall ML, Stevens S (October 2011). "Myalgic encephalomyelitis: International Consensus Criteria". J Intern Med. 270 (4): 327–338. doi:10.1111/j.1365-2796.2011.02428.x. PMC 3427890. PMID 21777306. Findings of 'small heart' with small left ventricular chamber and poor cardiac performance in patient subsets [109, 110] support previous reports of cardiac and left ventricular dysfunction [13, 111, 112], which predispose to orthostatic intolerance [14, 113]. Low blood pressure and exaggerated diurnal variation may be due to abnormal blood pressure regulation [114]. Altered control and reduced cortisol production during and following exercise may be involved. Orthostatic intolerance is associated with functional impairment and symptom severity [115]. Measurable vascular abnormalities suggest that the brain is not receiving sufficient circulating blood volume in an upright position [12, 113], which is intensified when standing in one place such as a grocery store check-out line. Significant reduction in heart rate variability during sleep is associated with poor sleep quality and suggests a pervasive state of nocturnal sympathetic hypervigilance [116].
  9. ↑ Nelson MJ, Bahl JS, Buckley JD, Thomson RL, Davison K (October 2019). "Evidence of altered cardiac autonomic regulation in myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review and meta-analysis". Medicine (Baltimore). 98 (43) e17600. doi:10.1097/MD.0000000000017600. PMC 6824690. PMID 31651868.
  10. ↑ Yoshiuchi K, Farkas J, Natelson BH (March 2006). "Patients with chronic fatigue syndrome have reduced absolute cortical blood flow". Clin Physiol Funct Imaging. 26 (2): 83–86. doi:10.1111/j.1475-097X.2006.00649.x. PMID 16494597.
  11. ↑ Newton JL, Sheth A, Shin J, Pairman J, Wilton K, Burt JA, Jones DE (April 2009). "Lower ambulatory blood pressure in chronic fatigue syndrome". Psychosom Med. 71 (3): 361–365. doi:10.1097/PSY.0b013e31819ccd2a. PMID 19297309.
  12. 1 2 Fu Q, Vangundy TB, Galbreath MM, Shibata S, Jain M, Hastings JL, Bhella PS, Levine BD (June 2010). "Cardiac origins of the postural orthostatic tachycardia syndrome". J Am Coll Cardiol. 55 (25): 2858–2868. doi:10.1016/j.jacc.2010.02.043. PMC 2914315. PMID 20579544. Autonomic function was intact in POTS patients. The marked tachycardia during orthostasis was attributable to a small heart coupled with reduced blood volume. Exercise training improved or even cured this syndrome in the majority of patients. It seems reasonable to offer POTS a new name based on its underlying pathophysiology – "The Grinch Syndrome", because in this famous children's book by Dr. Seuss, the main character had a heart that was "two sizes too small."
  13. 1 2 Strassheim, Victoria; Ballantine, Robert; Hackett, Katie L.; Frith, James; Newton, Julia L. (4 July 2017). "Understanding severely affected chronic fatigue syndrome (CFS): the gravity of the situation". Physical Therapy Reviews. 22 (3–4): 197–201. doi:10.1080/10833196.2017.1327131. ISSN 1083-3196. Retrieved 6 April 2026.
  14. ↑ Nunes JM, Kell DB, Pretorius E (July 2023). "Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses". Blood Rev. 60 101075. doi:10.1016/j.blre.2023.101075. PMC 10027292. PMID 36963989.
  15. ↑ van Campen CL, Rowe PC, Visser FC (May 2021). "Deconditioning does not explain orthostatic intolerance in ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome)". J Transl Med. 19 (1) 193. doi:10.1186/s12967-021-02819-0. PMC 8097965. PMID 33947430.
  16. ↑ Solomon N, Sailer A, Dixe de Oliveira Santo I, Pillai A, Heng LX, Jha P, Katz DS, Zulfiqar M, Sugi M, Revzin MV (2022). "Sequelae of Eating Disorders at Imaging". Radiographics. 42 (5): 1377–1397. doi:10.1148/rg.220018. PMID 35930473. Cardiac Manifestations.— Generally observed in particularly malnourished patients, Teaching Point small heart syndrome is characterized by the presence of a small heart shadow (ie, a cardiothoracic ratio ≤ 0.42) on a posteroanterior chest radiograph and is associated with nonspecific clinical symptoms including weakness, fatigue with mild exertion, and dyspnea (Fig 4) (17,18). Although other medical conditions such as cancer-induced cachexia can manifest with small heart syndrome, the presence of this finding in young patients with no underlying health issues should raise suspicion for an underlying ED.
  17. ↑ Takata T, Ishikawa K, Yachida T, Kobara H, Masaki T, Masugata H (May 2021). "Severe Small Heart Syndrome in a Patient with Anorexia Nervosa". Am J Med. 134 (5): e315–e316. doi:10.1016/j.amjmed.2020.10.033. PMID 33301733.
  18. ↑ Laennec RTH: Traite de L'auscultation Mediate et des Maladies des ´ Poumons et du Coeur (Eds. Chaude JS), pp. 496–497, JS Chaude, Paris, 1826
  19. ↑ Miwa K (July 2015). "Cardiac dysfunction and orthostatic intolerance in patients with myalgic encephalomyelitis and a small left ventricle". Heart Vessels. 30 (4): 484–489. doi:10.1007/s00380-014-0510-y. PMID 24736946.
  20. ↑ Hollingsworth KG, Hodgson T, Macgowan GA, Blamire AM, Newton JL (March 2012). "Impaired cardiac function in chronic fatigue syndrome measured using magnetic resonance cardiac tagging". J Intern Med. 271 (3): 264–270. doi:10.1111/j.1365-2796.2011.02429.x. PMC 3627316. PMID 21793948.
  21. ↑ Newton JL, Finkelmeyer A, Petrides G, Frith J, Hodgson T, Maclachlan L, MacGowan G, Blamire AM (2016). "Reduced cardiac volumes in chronic fatigue syndrome associate with plasma volume but not length of disease: a cohort study". Open Heart. 3 (1) e000381. doi:10.1136/openhrt-2015-000381. PMC 4932290. PMID 27403329.
  22. ↑ Tomas C, Finkelmeyer A, Hodgson T, MacLachlan L, MacGowan GA, Blamire AM, Newton JL (2017). "Elevated brain natriuretic peptide levels in chronic fatigue syndrome associate with cardiac dysfunction: a case control study". Open Heart. 4 (2) e000697. doi:10.1136/openhrt-2017-000697. PMC 5761285. PMID 29344367.
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