Acute coronary vasospasm secondary to industrial nitroglycerin withdrawal : a case presentation and review
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A Black employee exposed to industrial nitroglycerin (NG) in an explosives factory presented with severe precordial pain. The clinical presentation was that of significant transient anteroseptal and anterolateral transmural myocardial ischaemia which responded promptly to sublingual isosorbide dinitrate. Despite being removed from exposure to industrial NG and receiving therapy with long-acting oral nitrates and calcium antagonists, the patient continued to experience repeated attacks of severe retrosternal pain, although transient myocardial ischemia was not demonstrated electrocardiographically during these episodes. Cardiac catheterization revealed a normal myocardial haemodynamic system and selective coronary arteriography delineated coronary arteries free from any obstructive lesions. An ergonovine (ergometrine) maleate provocative test failed to elicit coronary artery spasm, although this was undertaken while the patient was on nitrate and calcium-blocker therapy. Clinical records of previous significant constrictive pericarditis (probably due to tuberculosis) with resultant abnormalities on the ECG complicated the diagnosis. Evaluation was further hindered by the known 'variant pattern' seen on the ECGs of members of the Black population. We postulate that this patient's clinical features were a direct result of severe vasospasm affecting the left coronary artery; it is also strongly suggested that withdrawal from contact with industrial NG precipitated this potentially lethal coronary vasospasm. The role played by industrial NG in ischaemic heart disease is reviewed, as well as the importance of the 'normal variant pattern' in the assessment of cardiac disease in Black patients. As far as we are aware this is the first time that the use of the ergonovine maleate provocative test has been documented in the industrial NG withdrawal syndrome.