Dextrocardia with Situs Inversus, Atrio-ventricular and Ventriculararterial Concordance and a Left Posterior Aorta in a Preterm Twin Neonate

Abstract

In dextrocardia, the main base-apex cardiac axis is directed to the right side of the chest. The majority of dextrocardia is associated with situs solitus and either normally related or L-transposed great vessels. Dextrocardia with situs inversus is rare and presents in different forms depending on the atrio-ventricular (AV) and ventricular-aterial (VA) relationship. We report a rare case of dextrocardia with situs inversus, AV and VA concordance, a left posterior aorta and a right aortic arch in a preterm twin male infant. IntroductionThe main cardiac axis (base to apex) determines the orientation of the heart in the chest. In dextrocardia, the axis points to the right instead of the left [1][2][3][4]. This differs from dextro position where the heart is positioned in the right side of the chest secondary to a pathologic process, but retains the normal axis [4]. Dextrocardia may occur as an isolated defect or may be associated with cardiac, vascular and/or visceral abnormalities. The relationship between the atria and viscera may present in one of three possible forms: situs solitus, situs inversus, or situs ambiguous. Situs solitus is the usual anatomy with the right atrium and the liver on right, and the stomach on the left. Situs inversus describes reversal of the viscera with the right atrium and the liver on the left and the stomach and the spleen on the right. Situs ambiguous, also called heterotaxy, describes an indeterminate situs and is usually associated with either asplenia or polysplenia. The ventricles may be concordant or discordant with their corresponding atria. The great arteries may be normally related, inversely related (mirror image), or transposed [5]. Case ReportA 32-week twin a male infant, weighing 1810 grams, was born to a 32 year-old G5P1 mother. This was a di-di twin pregnancy with IUGR in twin B. The pregnancy was complicated by in-vitro fertilization, gestational diabetes, hypothyroidism "on levothyroxine", preeclampsia "on magnesium sulfate", and preterm labor. The mother underwent C-section due to worsening pre-eclampsia. Both twins were given basic neonatal care. APGARs cores were 8 and 9 at 1 and 5 minutes, respectively. They had stable vital signs with oxygen saturation of 97% on room air. While twin B had a normal examination, twin A was incidentally noted to have heart sounds on the right side of the chest. No murmurs were appreciated. A chest X-ray (Figure 1) revealed dextrocardia with situs inversus, which was further confirmed by an abdominal ultrasound.An echocardiogram showed a mirror image dextrocardia with inversion of both atria and ventricles (Figure 2). The great arteries were also inverted with the pulmonary artery connected to a morphologic right ventricle on the left (Figure 3), and the aorta connected to a morphologic left ventricle on the right (Figure 4). There was a rightsided aortic arch as shown by the direction of the arch and its first bifurcating branch (Figure 4). The aortic valve was noted to be on the left and slightly posterior to the pulmona...