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A 48 year old smoker with atypical chest pain and a positive exercise test was referred for percutaneous coronary intervention to the right coronary artery (RCA). Coronary angiography had shown an unobstructed left system and three discreet critical stenoses in the RCA (middle upper and lower panels). Pre-intervention angiography was performed via a Right Judkins 3.5 French guide catheter, following routine intracoronary injection of isosorbide dinitrate. Interestingly, the RCA was found to be unobstructed in multiple views (right upper and lower panels). The stenoses apparent at diagnostic angiography were likely to have been a manifestation of catheter induced spasm; the use of intracoronary nitrates at repeat angiography prevented an unwarranted interventional procedure. The patient was discharged on oral diltiazem and is well six months later.
Coronary spasm during selective angiography is the result of interplay between increased vasomotor tone and a myogenic reflex triggered by mechanical stimulation by the catheter tip. Spasm involving the coronary ostium may be suspected because of damping and ventricularisation of the pressure waveform, but more distal spasm is often indistinguishable from fixed obstructive coronary disease. The angiographic appearances of catheter induced spasm can mimic a wide spectrum of obstructive disease, including left main stem stenosis, two vessel disease or diffuse three vessel disease. Failure to identify and control for coronary spasm may lead to inappropriate revascularisation and medical treatment as well as potential medico-legal problems.
Routine use of intracoronary nitrates in all patients undergoing diagnostic angiography would minimise the confounding effects of vasospasm and enhance reproducibility of coronary measurements.