Published online by Cambridge University Press: 14 March 2018
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.
We aimed to describe the haemodynamic effects of isoproterenol in patients with coarctation and the impact of intervention on the elicited gradients.
A retrospective study was performed on two-ventricle patients who underwent cardiac catheterisation for coarctation with isoproterenol testing.
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 (p<0.0001). In patients with a baseline gradient ⩽20 mmHg (n=17) at catheterisation, the median gradient increased from 10 (0–20) to 30 (15–50) mmHg (p<0.0001) with isoproterenol. Of these, 15 patients developed a gradient >20 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).
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.