The role of isoproterenol in the preoperative evaluation of high-pressure, high-resistance ventricular septal defect.

The experience we describe derives from the short-term administration of isoproterenol in 15 patients with ventricular septal defect (VSD) and severe pulmonary artery hypertension (PAH). For the whole study group, mean pulmonary artery pressure (PAP) was 68.5 +/- 2.6 mm Hg, pulmonary vascular resistance (Rp) was 11.6 +/- 0.9 U/m2, pulmonary vascular resistance/systemic vascular resistance ratio (Rp/Rs) was 0.9 +/- 0.03, and the pulmonary vascular gradient (PAd-PWP) was 45 +/- 3.5 mm Hg. Infusions of isoproterenol decreased PAP, Rp, Rp/Rs ratio, and PAd-PWP an average of 10.2 mm Hg, 2.88 U/m2, 0.13 and 6.6 mm Hg, respectively, for the whole group (P less than 0.001). On the basis of isoproterenol response, the patients could be divided into two groups: A (n = 4) and B (n = 11). In group A, the PAP decreased from 61.7 +/- 1 to 45 +/- 4 mm Hg, the Rp from 8.9 +/- 0.3 to 4.62 +/- 0.5 U/m2, the Rp/Rs from 0.84 +/- 0.02 to 0.55 +/- .05, and the PAd-PWP from 34.5 +/- 0.9 to 24 +/- 2 mm Hg (mean +/- 1 SE). In group B a less significant change in these measurements was observed. Group A patients underwent VSD repair, and the mean average postoperative decrease in PAP was 31 mm Hg (P less than 0.001). Our findings suggest that in patients with VSD and severe PAH, in whom surgical treatment is controversial, a trial with isoproterenol should be routinely attempted. If the preceding hemodynamic parameters improve significantly, the VSD repair should be performed.