| CPC A61N 1/3756 (2013.01) [A61N 1/0573 (2013.01); A61N 1/37512 (2017.08); A61N 1/37518 (2017.08)] | 24 Claims |

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1. A leadless biostimulator comprising:
a housing sized and configured to be disposed within a heart chamber of
a primary fixation element configured to actively affix the biostimulator to a heart wall within the heart chamber; and
an expandable structure connected to a proximal portion of the housing, the expandable structure being adapted to assume a compressed linear configuration during delivery and an expanded configuration after delivery, wherein the expanded configuration of the expandable structure has a cross-sectional dimension that is greater than a diameter of a vascular exit pathway from the heart chamber so that expansion of [ the ] expandable structure confines the leadless biostimulator and the expandable structure to the heart chamber [ , wherein the expandable structure further comprises a coupling mechanism that couples the expandable structure to the housing to allow for movement of the expandable structure with respect to the housing] .
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