Objective
To compare interstage cardiac catheterization hemodynamic and angiographic findings between shunt types for Single Ventricle Reconstruction (SVR) trial.
Background
The SVR trial, which randomized subjects to modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS) for the Norwood procedure, demonstrated RVPAS was associated with smaller pulmonary artery diameter, but superior 12-month transplant-free survival.
Methods
We analyzed pre-stage II catheterization data for SVR trial subjects. Hemodynamic variables and shunt and pulmonary angiography were compared between shunt types; their association with 12-month transplant-free survival was also evaluated.
Results
Of 549 randomized subjects, 389 underwent pre-stage II catheterization. Smaller size, lower aortic and superior vena cava saturation, and higher ventricular end-diastolic pressure (EDP) were associated with worse 12-month transplant-free survival. MBTS subjects had lower coronary perfusion pressure (27mmHg vs. 32mmHg, P<0.001) and higher Qp:Qs ratio (1.1 vs. 1.0, P=0.009). Higher Qp:Qs ratio increased the risk of death or transplant only in the RVPAS group (P=0.01). MBTS subjects had fewer shunt (14% vs. 28%, P=0.004) and severe left pulmonary artery stenoses (0.7% vs. 9.2%, P=0.003), larger mid-main branch pulmonary artery diameters and higher Nakata index (164 vs. 134, P<0.001).
Conclusions
Compared with RVPAS subjects, MBTS subjects had more hemodynamic abnormalities related to shunt physiology, while RVPAS subjects had more shunt or pulmonary obstruction of a severe degree, and inferior pulmonary artery growth at pre-stage II catheterization. Lower BSA, higher ventricular EDP, and lower SVC saturation were associated with worse 12-month transplant-free survival.