Significant left ventricular unloading with transaortic catheter venting during venoarterial bypass

Insufficient unloading of the left ventricle with blood stagnation is a main cause of unsuccessful left ventricular (LV) recovery during percutaneous cardiopulmonary support (PCPS). The purpose of this investigation was to evaluate the effectiveness of transaortic catheter venting (TACV) for LV unloading. Six adult mongrel dogs (mean weight 16.3 kg, range 14-20 kg) underwent venoarterial bypass (VAB) with TACV. Bypass flow ranged from 0.8-1.2 L/min, and TACV flow ranged from 160-240 ml/min. In addition to monitoring the standard hemodynamic parameters, the slope of the LV end-systolic pressure-volume relation (Emax) during transient occlusion of the inferior vena cava, the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the stroke work (SW), the LV pressure-volume area (PVA), and the slope of the SW end-diastolic volume relation, the preload recruitable stroke work (PRSW) were assessed by means of a microtip manometer and a conductance catheter. The LV contractility (Emax) and aortic elastance (Ea) were equivalent in the 2 groups with or without TACV (7.7 +/- 1.1 versus 8.4 +/- 1.5 mm Hg/ml and 8.2 +/- 1.4 versus 7.6 +/- 1.3 mm Hg/ml). Comparing the measurements for the baseline to those for VAB with TACV, the SW was significantly reduced, and the PVA/SW was increased by TACV (1,685 +/- 309 versus 867 +/- 188 x 10(-4) J, p < 0.05 and 1.32 +/- 0.03 versus 1.58 +/- 0.11, p < 0.05, respectively). Furthermore, the PRSW was gradually decreased from the baseline value to the value resulting from VAB with TACV (75 +/- 8 versus 44 +/- 3 x 10(-4) J/ml, p < 0.01). In comparison, the percent reduction of SW between VAB and VAB with TACV tended to be increased by TACV (23.2 +/- 7.2% versus 46.9 +/- 7.7%, p = 0.05). These results suggest that TACV might reduce LV work (SW and PRSW) and might increase the LV energetic charge. In conclusion, TACV would be an adjunctive technique to VAB or PCPS for patients with LV failure.