The left heart after pulmonary valve replacement in adults late after tetralogy of Fallot repair.

BACKGROUND: Adverse ventricular-ventricular interactions have been recognized in those with repaired tetralogy of Fallot (TOF) and severe pulmonary regurgitation. OBJECTIVE: We aimed to examine the impact of pulmonary valve replacement (PVR) on the left heart late after TOF repair. METHODS AND RESULTS: Left ventricular (LV) volumes and ejection fractions (EF) were analyzed in adults with severe pulmonary regurgitation after TOF repair with cardiac magnetic resonance imaging (CMR) before and after PVR. Thirty-nine patients (median age 33[20-65] years) were reviewed. Post-PVR, LVEF improved significantly in the entire cohort (50 ± 9%→54 ± 7%, p<0.001) and in those with moderately impaired (defined as LVEF ≤ 45%) preoperative LVEF (38 ± 5%→47 ± 6%, p<0.0001), but was not statistically different in those with relatively preserved (defined as LVEF >45%) preoperative LVEF. By multivariate linear regression analysis to evaluate independent CMR predictors of improved LVEF post-PVR for the entire cohort, the only CMR variable to emerge was preoperative LVEF (p=0.012, regression coefficient -0.54, SE 0.13). Whereas PVR resulted in increased LV filling in patients with relatively preserved preoperative LVEF reflected by an increase in LV end-diastolic volumes (77 ± 10→82 ± 16 mL/m(2), p=0.05), LV end-systolic volumes decreased after PVR in patients with impaired preoperative LVEF (65 ± 12→54 ± 10 mL/m(2), p=0.001) but LV end-diastolic volumes were not significantly changed. CONCLUSION: When LVEF is decreased after TOF repair, PVR appears to have a salutary effect on postoperative LVEF, thereby supporting the concept of recovery of adverse right-left heart interactions. Mechanisms of left heart improvement post-PVR differ depending on degree of preoperative LV systolic dysfunction.

Generation of human embryonic stem cell-derived mesoderm and cardiac cells using size-specified aggregates in an oxygen-controlled bioreactor.

The ability to generate human pluripotent stem cell-derived cell types at sufficiently high numbers and in a reproducible manner is fundamental for clinical and biopharmaceutical applications. Current experimental methods for the differentiation of pluripotent cells such as human embryonic stem cells (hESC) rely on the generation of heterogeneous aggregates of cells, also called "embryoid bodies" (EBs), in small scale static culture. These protocols are typically (1) not scalable, (2) result in a wide range of EB sizes and (3) expose cells to fluctuations in physicochemical parameters. With the goal of establishing a robust bioprocess we first screened different scalable suspension systems for their ability to support the growth and differentiation of hESCs. Next homogeneity of initial cell aggregates was improved by employing a micro-printing strategy to generate large numbers of size-specified hESC aggregates. Finally, these technologies were integrated into a fully controlled bioreactor system and the impact of oxygen concentration was investigated. Our results demonstrate the beneficial effects of stirred bioreactor culture, aggregate size-control and hypoxia (4% oxygen tension) on both cell growth and cell differentiation towards cardiomyocytes. QRT-PCR data for markers such as Brachyury, LIM domain homeobox gene Isl-1, Troponin T and Myosin Light Chain 2v, as well as immunohistochemistry and functional analysis by response to chronotropic agents, documented the impact of these parameters on cardiac differentiation. This study provides an important foundation towards the robust generation of clinically relevant numbers of hESC derived cells.