Definition of "acardiac" [a•car•di•ac]

• Lacking a heart. (adjective)

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• "When blood flows in reverse through an acardiac twin (one without a functioning heart) as it is pumped by the other, typically normal twin."
• "The term “reversed perfusion” is used to describe this scenario because blood enters the acardiac/acephalic twin through reversed flow through its umbilical artery and exits through the umbilical vein, which is opposite to the normal blood supply of the fetus."
• "In the TRAP sequence, the acardiac/acephalic twin receives all of its blood supply from the normal, or so-called pump twin."