Final answer:
The recipient twin in poly-oli is larger mainly due to receiving more blood, not directly because of heart failure. Heart failure can occur as a secondary complication due to the added stress on the heart from the increased blood volume.
Step-by-step explanation:
The statement 'the recipient twin in poly-oli (polyhydramnios-oligohydramnios sequence) is larger because of heart failure' is generally false. In twin-to-twin transfusion syndrome (TTTS), which includes the poly-oli sequence, the recipient twin receives more blood than the donor twin. This can lead to the recipient twin becoming larger due to the extra blood volume and nutrients, not directly because of heart failure. However, as a consequence of the increased workload on the recipient twin's heart due to the increased blood volume, the heart can indeed become stressed and eventually could lead to heart failure. The size difference is primarily the result of the imbalanced blood exchange, not heart failure, which is a potential secondary complication.