VDH and DAH are two acronyms that are often seen in men’s army service records. They both relate to heart trouble.
VDH means valvular disease of the heart. It is the more serious of the two and implies some organic disease or heart malfunction;
DAH means disorderly action of the heart, sometimes called “effort syndrome” or “soldier’s heart”. Often the result of stress or fatigue, it does not imply there was any organic disease.
From “Medical Diseases of the War” by Sir Arthur F. Hurst (London: Edward Arnold, 1918):
“The importance of the effort syndrome can be gathered from the fact that 2,503 out of 33,919, or 7.4 per cent, of the soldiers and sailors invalided from the services from the beginning of the war up to May 31st 1916, were discharged on account of ‘heart disease,’ and by May 1918 the number had risen to 36,569. The problem of invaliding on account of ‘soldier’s heart’ became such a serious one that the War Office and Medical Research Council arranged for the segregation of heart cases at the Hampstead Hospital under Thomas Lewis. Later the work was transferred to Colchester, and finally centres were established for heart cases in each home command. At the same time it became recognised in France that many cases were being sent to England with an erroneous diagnosis of valvular disease of the heart and still more with trivial cardiac symptoms. In 1916 all cases sent to one base diagnosed as VDH and DAH were collected in a single centre under Colonel W. E. Hume, and in 1917 similar centres were started at four other bases. At these centres DAH was so successful that 50 per cent of cases were detained for duty in France, but far too many escaped diagnosis and reached England without having passed through any heart centre.”