Unmasking the borderline coarctation: the utility of isoproterenol in the paediatric cardiac catheterisation laboratory.

BACKGROUND: One indication for intervention in coarctation of the aorta is a peak-to-peak gradient >20 mmHg. Gradients may be masked in patients under general anaesthesia and may be higher during exercise. Isoproterenol was given during cardiac catheterisation to simulate a more active physiologic state.

OBJECTIVES: We aimed to describe the haemodynamic effects of isoproterenol in patients with coarctation and the impact of intervention on the elicited gradients.

METHODS: A retrospective study was performed on two-ventricle patients who underwent cardiac catheterisation for coarctation with isoproterenol testing.

RESULTS: 25 patients received isoproterenol before and after intervention. With isoproterenol, the mean diastolic (p=0.0015) and mean arterial (p=0.0065) blood pressures proximal to the coarctation decreased significantly. The mean systolic, diastolic, and mean arterial blood pressures distal to the coarctation decreased significantly (p20 mmHg. Post intervention, the median gradient decreased to 2 (0-29) mmHg, versus baseline, p=0.005, and with isoproterenol it decreased to 8 (0-27) mmHg, versus pre-intervention isoproterenol, p<0.0001. There were significant improvements in the gradients by Doppler (<0.0001) and by blood pressure cuff (p=0.0313). The gradients on isoproterenol best correlated with gradients by blood pressure cuff in the awake state (R2=0.76, p<0.0001).

CONCLUSIONS: Isoproterenol can be a useful tool to assess the significance of a coarctation and the effectiveness of an intervention. Percutaneous interventions can effectively reduce the gradients elicited by isoproterenol.