Volume overload refers to the state of one of the chambers of the heart in which too large a volume of blood exists within it for it to function efficiently. Ventricular volume overload is approximately equivalent to an excessively high preload. It is a cause of cardiac failure.[1]

Representation of the cardiac response in stroke volume to left ventricular filling under normal conditions. There is an optimum end-diastolic volume at which maximum stroke volume and cardiac output is achieved. Beyond this, there is volume overload, and stroke volume is diminished.

Pathophysiology

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In accordance with the Frank–Starling law of the heart, the myocardium contracts more powerfully as the end-diastolic volume increases. Stretching of the myofibrils in cardiac muscle causes them to contract more powerfully due to a greater number of cross-bridges being formed between the myofibrils within cardiac myocytes.[2] This is true up to a point, however beyond this there is a loss of contractile ability due to loss of connection between myofibrils; see figure.[citation needed]

Various pathologies, listed below, can lead to volume overload. Different mechanisms are involved depending on the cause, however the common theme is that of a high cardiac output with a low or normal afterload. The output may be high due to the inefficiency in valve disease, or it may be high due to shunting of blood in left-to-right shunts and arteriovenous malformations.[citation needed]

Left ventricular volume overload may produce inverted u waves on the electrocardiogram.[3]

Causes

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Causes may be considered according to which chamber is affected.[citation needed]

Left ventricular volume overload

Right ventricular volume overload

See also

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References

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  1. ^ Costanzo, Linda S. (2007). Physiology. Hagerstwon, MD: Lippincott Williams & Wilkins. pp. 81. ISBN 978-0-7817-7311-9.
  2. ^ Klabunde, Richard E. "Cardiovascular Physiology Concepts". Lippincott Williams & Wilkins, 2011, p. 74.
  3. ^ Conrath C, Opthof T (2005). "The patient U wave". Cardiovasc Res. 67 (2): 184–6. doi:10.1016/j.cardiores.2005.05.027. PMID 15979057.
  4. ^ Left Ventricular Volume Overload, Discussion of echocardiography findings.
  5. ^ Gehl LG, Mintz GS, Kotler MN, Segal BL (1982). "Left atrial volume overload in mitral regurgitation: a two dimensional echocardiographic study". Am J Cardiol. 49 (1): 33–8. doi:10.1016/0002-9149(82)90274-0. PMID 7053608.
  6. ^ a b Gardiner M, Eisen S, Murphy C. Training in paediatrics: the essential curriculum. Oxford University Press, Oxford 2009.