Dextrocardia is an abnormal congenital positioning of the heart in which, instead of the heart forming in the fetus on the left side, it flips over and forms on the right. There are several types of this condition, also called looping defects. It is frequently diagnosed in a routine prenatal sonogram, although not every radiologist will catch it, particularly if there are no cardiac structural abnormalities.
Mirror image dextrocardia is a very rare condition, present in about one in 130,000 people. In this looping defect, not only does the heart flip the wrong way and develop on the wrong side of the chest, but also all the other organs in the middle of the body are reversed. In essence, an X-ray of someone with this problem looks like a mirror image of the normal heart and organ placement.
This abnormality was first noted in the 1920s, when X-rays revealed this abnormal placement. Fortunately, this type of looping defect does not involve structural abnormalities of the heart or other organs. In some cases, cilia — the tiny hair-like structures — in the nose and lungs move in the opposite direction, causing a greater susceptibility to colds or illness. Aside from this susceptibility, a person with this condition does not require any special treatment or surgeries.
Dextrocardia with abnormal heart is a far more serious condition, which usually requires one or more surgeries to address structural abnormalities. It is a more common condition than the mirror image abnormality, and in most cases, the position of the other organs in the middle of the body is not reversed. The outcome and survival rates for this problem depends upon the severity of the defects, which generally include a complicated form of transposition of the arteries, called levo-transposition, or both arteries arising from the right ventricle, called double outlet right ventricle.
Large ventricular septal defects are also common in those with this condition. The right and left ventricle may be so similar, unlike in the normal heart, that it is difficult to differentiate which ventricle is which. In many cases, the ventricular septal defect is so large that these chambers are considered a single one, and one or both ventricles may be smaller than usual.
With complicated transposition and single ventricle, two surgical approaches are possible. If the ventricles are large enough, surgeons may elect to perform a Rastelli, one and a half ventricle repair. This surgery constructs a tunnel through the heart to properly reroute the blood. If possible, the ventricular septal defect may be repaired. Prior to this treatment, however, the superior vena cava is directed to the smaller pulmonary veins, and blood from the upper body never passes through the right ventricle. This initial procedure, called the Glenn shunt, reduces the heart’s workload and buys time for the child to grow before performing the Rastelli.
The Rastelli has an excellent survival rate, once past the initial surgery. It is a complicated and often lengthy procedure, with the main disadvantage of it being the length of time a child may need to be on heart lung bypass. A parent should ask a surgeon about his or her experience and success rate with this or any other surgery. Further surgical intervention may be necessary in the form of pulmonary or aortic valve replacements several years after the initial Rastelli.
Levo-transposition, small ventricles, and a high degree of pulmonary stenosis in dextrocardia with abnormal heart generally requires the three-staged Fontan operation. In this case, the surgeon performs three surgeries to palliate the defects. Improvement in the Fontan has led to improved survival rates, and many children born with this condition live well into their 30s before ultimately needing a heart transplant, the only true fix for single ventricle.
Dextrocardia may also be present in a condition called heterotaxy, which involves not only abnormal heart placement and structural abnormalities, but also the absence of a spleen or the presence of a number of small spleens. Treatment depends upon the degree and severity of these structural anomalies. Lack of a spleen, asplenia, can complicate any operations because natural resistance to infection is significantly reduced.