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Insufficient unloading of the left ventricle (LV) is a limitation of percutaneous cardiopulumonary support (PCPS). We previously reported the unloading effect of transaortic catheter venting (TACV) during venoarterial bypass (VAB) in normal hearts. The aim of this study was to assess the effectiveness of TACV with VAB in a heart failure (HF) model. Seven adult mongrel dogs underwent TACV with VAB, and isolated LV failure was induced by multiple ligation of left coronary arteries. With standard hemodynamic monitoring, slope of the LV end-systolic pressure-volume relationship (Emax; mm Hg/ml), aortic elastance (Ea; mm Hg/ml), LV stroke work (SW; 10(-4)J), preload recruitable stroke work (PRSW; 10(-4)J/ ml), LV pressure-volume area (PVA; 10(-4)J), and potential energy (PE; 10(-4)J) were assessed using a micro-tip manometer and a conductance catheter. In addition to evaluation of LV function, myocardial adenosine 5'-triphosphate (ATP) was measured in each condition. The TACV combined support significantly reduced LV total energy (PVA) and LV work (SW). The LV energetic charge (PE/PVA, myocardial ATP) was significantly increased by TACV. These results suggest that TACV might be an effective technique for LV recovery during VAB or PCPS in patients with severe heart failure.

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.

Left dominant biventricular failure is a common type of heart failure after cardiac surgery. We developed a biventricular bypass (BVB) system for treatment of postcardiotomy ventricular failure, and we previously reported that the clinical results of the BVB system were superior to those obtained with venoarterial bypass (VAB). The purpose of this study was to evaluate the effect of the BVB system on left ventricular (LV) performance in comparison to that of VAB by means of the LV pressure-volume relationship (PVR). Eight adult mongrel dogs (14-21 kg) underwent VAB with right atrial and aortic cannulation. Left atrial cannulation was added for BVB, and both atrial drainage tubes were joined with a Y-shaped connector. The bypass flow was maintained at half of the baseline cardiac output (0.7-1.0 L/min), and the hemodynamic parameters were monitored. A high fidelity microtip catheter and a conductance catheter were used to evaluate LV function. The slope of the LV end-systolic pressure-volume relation (Emax), the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the LV stroke work (SW), LV potential energy (PE), LV pressure-volume area (PVA), the slope of the SW end-diastolic volume relation (PRSW), and an index of the LV energizing charge (ratio of PE/PVA) were assessed during transient occlusion of the inferior vena cava. LV contractility (Emax) showed no significant change during each experiment. Standardized LV work (PRSW) was reduced by BVB in comparison to the baseline and in comparison to VAB. The rate of LV energy charge (PE/PVA) significantly increased only during BVB. These results suggested that the BVB system might be an effective circulatory support for reducing LV work and improving the LV energizing charge in patients with severe heart failure after cardiac operation.

Although venoarterial bypass (VAB) or percutaneous cardiopulmonary support (PCPS) can improve hemodynamics in patients with serious cardiac decompression, some cannot be weaned from circulatory support. Insufficient unloading of the left ventricle (LV) with blood stagnation is a main cause of unsuccessful LV recovery during PCPS. This investigation was undertaken to evaluate the effectiveness of transaortic catheter venting (TACV) for LV unloading. Eight mongrel dogs (mean weight 16.3 kg, range 14-20 kg) underwent VAB with TACV. In addition to monitoring standard hemodynamic parameters, the slope of the LV end systolic pressure-volume relationship (Emax) during transient occlusion of the inferior vena cava, the slope of LV end systolic pressure-stroke-volume (Ea), external stroke work (SW), LV pressure-volume area (PVA), and slope of the SW-end diastolic volume relationship (preload recruitable stroke work: PRSW) were assessed by means of a micro-tip manometer and a conductance catheter. We measured data under the following four conditions; before circulatory support (baseline), during isolated VAB, VAB with TACV, and VAB with TACV plus intra-aortic balloon pumping (IABP). The LV contractility (Emax) and LV elastance (Ea) were equivalent for the four conditions. By comparison with baseline and VAB with TACV, LV energy (PVA) and work (SW, PRSW) were significantly reduced by TACV (1283.9 +/- 197.1 vs. 793.3 +/- 124.8 x 10(-4) J, 897.1 +/- 147.2 vs. 474.2 +/- 83.0 x 10(-4) J and 35.6 +/- 2.7 vs. 25.7 +/- 1.7 x 10(-4) J/ml, respectively), and the PE/PVA increased with TACV (30.4 +/- 2.6 vs. 40.8 +/- 1.8%). In contrast, there was no significant difference in PVA, SW, PRSW, and PE/PVA between baseline and isolated VAB. These results suggest that TACV might be an adjunctive technique to VAB or PCPS for patients with LV failure.

A safe and reliable method of weaning from a left ventricular assist system (LVAS) is necessary for successful circulatory support in patients with marginal heart failure. The purpose of this study is to assess the effect of additional intraaortic balloon (IAB) support during weaning from an LVAS by means of the LV pressure-volume relationship. A pneumatic LVAS with a sac-type blood pump was implanted in six adult mongrel dogs weighing 14 to 20 kg. All dogs had a drainage cannula placed in the left atrium and an outflow conduit in the ascending aorta. Hemodynamic parameters, pulmonary arterial flow, and pump output were monitored. An IAB was inserted through the groin. A conductance catheter and microtip manometer were inserted into the LV cavity. As a combination driving mode, LVAS ejection in the early diastolic phase and IAB inflation in the late diastolic phase were applied. After evaluation of baseline LV function, the pressure-volume relationship was repeatedly measured during change of driving modes as isolated LVAS, LVAS + IAB (1:1), LVAS + IAB (2:1), and isolated IAB supports. Finally, LV failure was introduced by stepwise ligation of left coronary arteries, and the LV pressure-volume relationship was measured in each driving mode. Under normal conditions, the pressure-volume loop showed no significant change among the four driving modes. In contrast, the LV pressure-volume relationship significantly improved according to the degree of additional IAB support on LVAS assistance under the condition of LV failure. These results suggest that additional IAB support might improve LV energy during weaning from an LVAS.