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Background We havebeen attempting to use cardiac spheroids to construct three-dimensional contractilestructures for failed hearts. Recent studies have reported that neuralprogenitors (NPs) play significant roles in heart regeneration. However, theeffect of NPs on the cardiac spheroid has not yet been elucidated. Objective This studyaims to demonstrate the influence of NPs on the function of cardiac spheroids. Methods Thespheroids were constructed on a low-attachment-well plate by mixing humaninduced pluripotent stem (hiPS) cell-derived cardiomyocytes and hiPScell-derived NPs (hiPS-NPs). The ratio of hiPS-NPs was set at 0%, 10%, 20%,30%, and 40% of the total cell number of spheroids, which was 2500. The motionwas recorded, and the fractional shortening and the contraction velocity weremeasured. Results Spheroidswere formed within 48 h after mixing the cells, except for the spheroidscontaining 0% hiPS-NPs. Observation at day 7 revealed significant differencesin the fractional shortening (analysis of variance; p = 0.01). The bestfractional shortening was observed with the spheroids containing 30% hiPS-NPs.Neuronal cells were detected morphologically within the spheroids under aconfocal microscope. Conclusion Theaddition of hiPS-NPs influenced the contractile function of the cardiacspheroids. Further studies are warranted to elucidate the underlying mechanism.

The use of multiplane transesophageal echocardiography (TEE) to reconstruct 3-dimensional (3D) images is limited by time-consuming, multiplane image acquisition and the need for offline processing. To overcome these limitations, a 3D fully sampled matrix array transducer was recently developed to allow real-time acquisition and online display of 3D images. In this case, real-time 3D transesophageal echocardiography produced clear image of a small paraprosthetic leak point. Although the surgical view from the left atrium was poor due to severe adhesions, we were able to perform optimal repair of the small leak after intraoperative confirmation of the location of the leak that was identified by preoperative real-time 3D transesophageal echocardiography.