The Acardiac Monster

Abstract

Two cases of acardiac fetuses are presented. Pathological data in 61 cases are tabulated. Cliassification, terminology and patho-physiological findings are discussed. The Acardiac Monster is a form of monozygotic multiple gestation lacking a physiological heart and resulting in a bizarre fetal malformation which is sustained in utero by parasitic anastomoses to the circulation of a normal twin fetus. The precise etiology of this phenomenon is still obscure and suggestions are made for the future evaluation of the acardiac fetus.

Clinical and Anatomic Features of Acardiac Twins

“…Reports from the literature show that the frequency of acardius acephalus is greater than that of acardius anceps (68 and 8%, respectively) [7], but in our series, there were 3 cases each of acardius acephalus and acardius anceps.…”

“…Profound disorganization of multiple organ systems in acardiac fetuses has been revealed by careful dissections since early reports of the condition [1,[6][7][8]. Rapidly growing structures such as the branchial arches, maxilla, and mandible are rudimentary because of the severe loss of blood flow in early development, but some acardiac acephalic fetuses do possess teeth.…”

“…Rapidly growing structures such as the branchial arches, maxilla, and mandible are rudimentary because of the severe loss of blood flow in early development, but some acardiac acephalic fetuses do possess teeth. Many authors have reported pregnancy outcomes [1,3,7,8], which seem to be influenced by the weight of the acardiac fetus compared to that of the pump fetus (TWR) [8]. When TWR exceeds 50%, the prognosis of the normal fetus is worse.…”

Multiple Pregnancies

“…His statement, "…an anomaly, anatomical or functional, intraembryonic or extraembryonic, may turn one twin into an acardius if its circulation becomes dependent on that of the other embryo," probably best re fl ects our current thinking about the nature of these monsters. Lachman et al ( 1980 ) have also presented reasonable theories of etiology in their discussion of a relevant case.…”

When does death occur in an acardiac twin? Ultrasound diagnostic difficulties

“…The twin reverse arterial perfusion sequence (TRAP) is associated with four major types of abnormality: Acardius acephalus, with absence of fetal head and thoracic organs, myelacephalus with partially developed head and extremities, amorphus where there is no recognisable human shape, and acornus where only the fetal head develops [2]. TRAP sequence is lethal for the affected fetus, and causes death in up to 50% of normal co-twins, either from intrauterine cardiac failure or the sequelae of prematurity [8].…”