Da Costa's syndrome

# Overview
Da Costa's syndrome, which was colloquially known as soldier's heart, is a syndrome with a set of symptoms that are similar to those of heart disease, though a physical examination does not reveal any physiological abnormalities.  In modern times, Da Costa's syndrome is considered the manifestation of an anxiety disorder and treatment is primarily behavioral, involving modifications to lifestyle and daily exertion.
The condition was named for Jacob Mendes Da Costa, who investigated and described the disorder during the American Civil War. It is also variously known as cardiac neurosis, chronic asthenia, effort syndrome, functional cardiovascular disease, neurocirculatory asthenia, primary neurasthenia, subacute asthenia and irritable heart.

# Classification
The World Health Organization classifies this condition as a somatoform autonomic dysfunction (a type of psychosomatic disorder) in their ICD-10 coding system.  In their ICD-9 system, it was classified under non-psychotic mental disorders.    The syndrome is also frequently interpreted as one of a number of imprecisely characterized "postwar syndromes".
There are many names for the syndrome, which has variously been called cardiac neurosis, chronic asthenia, effort syndrome, functional cardiovascular disease, neurocirculatory asthenia, primary neurasthenia, and subacute asthenia.  Da Costa himself called it irritable heart and the term soldier's heart was in common use both before and after his paper.  Most authors use these terms interchangeably, but some authors draw a distinction between the different manifestations of this condition, preferring to use different labels to highlight the predominance of psychiatric or non-psychiatric complaints.  For example, Paul writes that "Not all patients with neurocirculatory asthenia have a cardiac neurosis, and not all patients with cardiac neurosis have neurocirculatory asthenia."  None of these terms have widespread use.

# Symptoms
Symptoms of Da Costa's syndrome include fatigue upon exertion, shortness of breath, palpitations, sweating, and chest pain.  Physical examination reveals no physical abnormalities causing the symptoms.

# Causes
Da Costa's syndrome is generally considered a physical manifestation of an anxiety disorder.

# Diagnosis
Although it is listed in the ICD-10 under "somatoform autonomic dysfunction", the term is no longer in common use by any medical agencies and has generally been superseded by more specific diagnoses.
The orthostatic intolerance observed by Da Costa has since also been found in patients diagnosed with chronic fatigue syndrome and mitral valve prolapse syndrome. In the 21st century, this intolerance is classified as a neurological condition. Exercise intolerance has since been found in many organic diseases.

# Treatment
The report of Da Costa shows that patients recovered from the more severe symptoms when removed from the strenuous activity or sustained lifestyle that caused them.
Other treatments evident from the previous studies were improving physique and posture, appropriate levels of exercise where possible, wearing loose clothing about the waist, and avoiding postural changes such as stooping, or lying on the left or right side, or the back in some cases, which relieved some of the palpitations and chest pains, and standing up slowly can prevent the faintness associated with postural or orthostatic hypotension in some cases.

# History
Da Costa's syndrome is named for the surgeon Jacob Mendes Da Costa, who first observed it in soldiers during the  physiological explanation for soldier's heart.  Use of the term "Da Costa's syndrome" peaked in the early 20th century. Towards the mid-century, the condition was generally re-characterized as a form of neurosis. It was initially classified as "F45.3" (under somatoform disorder of the heart and cardiovascular system) in ICD-10, and is now classified under "somatoform autonomic dysfunction".
Da Costa's syndrome involves a set of symptoms which include left-sided chest pains, palpitations, breathlessness, and fatigue in response to exertion. Earl de Grey who presented four reports on British soldiers with these symptoms between 1864 and 1868, and attributed them to the heavy weight of military equipment being carried in knapsacks which were tightly strapped to the chest in a manner which constricted the action of the heart. Also in 1864, Henry Harthorme observed soldiers in the American Civil War who had similar symptoms which were attributed to long-continued overexertion, with deficiency of rest and often nourishment, and indefinite heart complaints were attributed to lack of sleep and bad food. In 1870 Arthur Bowen Myers of the Coldstream Guards also regarded the accoutrements as the cause of the trouble, which he called neurocirculatory asthenia and cardiovascular neurosis.
J. M. Da Costas study of 300 soldiers reported similar findings in 1871 and added that the condition often developed and persisted after a bout of fever or diarrhoea. He also noted that the pulse was always greatly and rapidly influenced by position, such as stooping or reclining. A typical case involved a man who was on active duty for several months or more and contracted an annoying bout of diarrhoea or fever, and then, after a short stay in hospital, returned to active service. The soldier soon found that he could not keep up with his comrades in the exertions of a soldier's life as previously, because he would get out of breath, and would get dizzy, and have palpitations and pains in his chest, yet upon examination some time later he appeared generally healthy.  In 1876 surgeon Arthur Davy attributed the symptoms to military drill where over-expanding the chest, caused dilatation of the heart, and so induced irritability".
Since then, a variety of similar or partly similar conditions have been described.