Morphology of the cardiovascular system in conjoined twins: Spatial and sequential segmental arrangements in 36 cases

Abstract

Thirty-six pairs of conjoined twins are reviewed from the joint experience of the authors. The external forms of conjunctions were 18 thoracopagus (joined at chest), eight cephalothoracopagus (joined at head and chest), eight dicephalus (single trunk and two heads), one craniopagus (joined at head), and one omphalopagus (joined at abdomen). There was one case with a single conventional heart in association with isomerism of the left lungs and absence of the heart in the left-side twin. Six cases had two conventional hearts. All of them had associated lesions, which were more severe in three cases (50%) with abnormal laterality. All of the cephalothoracopagus (eight cases) had two shared hearts. Cardiac lesions were commonly seen in the posterior heart, but the arrangement of atrial appendages were normal in every heart. Twenty-one cases of either dicephalus or thoracopagus had a compound heart. Three cases (14%) had fusion only at the level of venous sinus; three others (14%) were fused at the atrial level only, but 15 cases (71%) had fusion at both atrial and ventricular levels. Abnormal laterality was an associated lesion in ten cases (48%) with a compound heart. The fusion at the atrial level always occurred between right atriums, but ventricular fusion was more commonly between two left ventricles. Four atrial or ventricular chambers, if fused, were arranged in a cruciate arrangement. Mode of conjunction was as important, in the formation of the cardiovascular system, as was the degree of fusion. Abnormal laterality, which is commonly associated in lateral or mixed lateral/facing conjunction, was the most important factor affecting the general morphology of the cardiovascular system.

Asplenia syndrome and isolated total anomalous pulmonary venous connection in siblings

“…A relationship between monozygous twinning and body axis determination has been suggested, since in conjoined twins, situs inversus is frequently found [9]. Also in monozygotic twins, an excess of lateralization defects has been observed [16].…”

First-Trimester Diagnosis of Conjoined Twins

“…In a monoamniotic monochorionic twin pregnancy, a constantly close position of the fetal heads and/or a fusion of some fetal body parts suggest the diagnosis of conjoined twins. The prognosis is based on a good knowledge of the mode of conjunction and the degree of fusion [4], Ultra sound imaging may clearly orientate the diagnosis and may show the presence of a single liver or heart. In more complex cases with partial fusion and abnormal laterality, the diagnosis of cardiac abnormalities may be hard to establish at the end of the first trimester when the 'fourchamber view' is difficult to see.…”

“…Several classi fications are used according to the type of conjunction [2,3]. Thoracopagus and omphalopagus are the most fre quent types [3,4], The fetal prognosis is very poor and options for a surgical conservative management are large ly dependent on the degree of fusion of the cardiovascular system and the liver [4], Antenatal diagnosis of conjoined twins was first made by means of traditional X-ray, by amniofetography [3] and, since 1977, by ultrasound [5]; during the second tri mester, some cases of conjoined twins have previously been reported [1,2], and recently a late first-trimester diagnosis has been published [6], In our cases, the diagnosis was made as early as 9 and 11 weeks using an endovaginal probe.…”

Cardiac catheterization in diagnosis and management of congenital heart disease in thoracopagus conjoined twins

“…Catheterization was not completed until the degree of atrial and ventricular fusion, the number and morphology of the atrioventricular valves, the number and morphology of the ventricles, the number and relationship of the great vessels, and the systemic and pulmonary venous drainage of both twins had been answered (Figs. [2][3][4][5][6][7][8]. At least one angiogram was performed in the inferior vena cava/hepatic vein (to delineate the degree of liver union and hepatic vein course), the SVC, the atrium, one or both ventricles, the pulmonary artery and aorta of each twin, unless angiography in the corresponding twin had fully elucidated the anatomy in the opposite twin (i.e., fused cardiac components).…”

“…Surgical separation of thoracopagus twins has become increasingly feasible with the significant advances made in the last decade by multidisciplinary teams, including general surgical, orthopedic, plastic, urology, and cardiac teams in both preoperative evaluation and postoperative care. The degree of cardiac involvement is usually the limiting factor for successful separation in thoracopagus twins, particularly without sacrificing one of the twins [5][6][7]. One of the crucial components of preoperative evaluation is the accurate delineation of cardiac anatomy.…”