ANGIOGRAPHIC DIAGNOSIS OF ANOMALOUS CORONARY-ARTERY IN TETRALOGY OF FALLOT

Objective-To obtain angiographic views in tetralogy of Fallot that can show whether or not an anomalous coronary artery passes anterior to t he right ventricular outflow tract. Design-(a) A 10 year retrospective review of all patients who underwent repair of tetralogy of Fallot up to December 1990; (b) a prospective study of 30 children undergoing r outine cardiac catheterisation. Patients and methods-295 cases in whom standard angiographic views had been used were reviewed retrospective ly. Thirty non-consecutive children with tetralogy of Fallot were stud ied prospectively, including one child previously studied in whom diag nosis of an unsuspected anomalous coronary artery was made only at ope ration. The aortogram was performed with greater-than-or-equal-to 45-d egrees caudocranial and 20-degrees-30-degrees left anterior oblique an gles. Setting-Tertiary referral centre. Results-Ten of the 295 cases r eviewed were shown to have a coronary vessel traversing the right vent ricular outflow tract. In one case the diagnosis was suspected before operation but it was missed in the others. Even in retrospect we could not be certain of the precise anatomy with the use of standard angiog raphic views. In the prospective study the caudocranial aortogram show ed the aortic valve face on in all the patients. The right ventricular outflow tract lay in a left and anterior (seen as superior) position in relation to the aortic root. Thus any vessel crossing the outflow t ract could be identified. Identification of the aortic cusps allowed p recise definition of the origin of the coronary arteries. All but four had normal origin and course of the coronary arteries. Four had paire d left anterior descending arteries (including the restudied patient), in all cases with a large vessel originating from the right coronary artery passing across the right ventricular outflow tract. Conclusions -Important anomalies of the coronary arteries in tetralogy of Fallot m ay remain undiagnosed if standard angiographic projections are used. A ortography with greater-than-or-equal-to 45-degrees caudocranial and 2 0-degrees-30-degrees left anterior oblique angles allows precise defin ition of the anatomy and certainty as to whether any major vessel cros ses the right ventricular outflow tract. Interpretation, however, can only be correct if the projection is technically adequate with a view of the aortic valve face on. Furthermore, a normal bifurcation of the left main stem does not exclude a second left anterior descending arte ry crossing the pulmonary outflow tract.