Ectopia Cordis – A rare congenital malformation

A Baby affected with ectopia cordis Image Courtesy:- TheFetus.Net

Ectopia cordis is a rare congenital malformation in which the heart is located partially or totally outside the thoracic cavity. It may occur as an isolated malformation or it may be associated with a larger category of verntral body wall defects that affect the thorax, abdomen or both. This is a very rare anomaly with an estimated prevalance of 0.079/10000 births and may occur more frequently in females. The prenatal diagnosis is easliy made with ultrasound by visualizing the heart outside the thoracic cavity. There are four types of ectopia cordis according to the position of the heart:-

1. Anterior to the sternum (thorcacic)
2. Between thorax and abdomen (thoracoabdominal)
3. Within abdomen (Abdominal)
4. In the neck (Crevical)

The thoracic and thoracoabdominal types are most common followed by the abdominal and crevical types. The combination of thoracoabdominal ectopia cordis, lower sternal defect, anterior diaphragmatic hernia, midline supraumblical defect along with pericardial and intracardiac defects constitue the Pentalogy of Cantrell

Pathogenesis

Thoracic Ectopia Cordis Image Courtesy:- PubMedCentral

Embryologically, the development of the ventral body wall begins after the eigth day of embryonic life with differentiation and proliferation of a mesodermal layer between the trophoblast and the endoderm. Lateral migration of the paired mesoderm then occurs. At about 16 days, the mesoderm splits laterally into an outer somatic layer and an inner splachnic layer with the coelomic cavity interspaced between. Ventromedial folding of the paired mesodermal layers gives septum transversum of the diaphragm, pericardium and epimyocardium (splanchnic mesoderm). The heart originally develops in a very cephalad location and reaches its definitive position by the lateral folding and ventral flexing of the embryo at about 16- 17 days of development. Midline fusion and formation of the thoracic and abdominal cavities is complete by the 9th embryonic weeks. Failure, either complete or partial, of midline fusion at this embroynic stage can result ina variety of disorders ranging from isolated ectopia cordis to complete ventral evisceration. Earlyl rupture of the chorion and /or yolk sac causing compression of the thorax preventing midline fusion has been proposed as mechinal cause of these defects as has early rupture of the amnion with formation of fibrous amniotic bands. Ectopia cordis has been attributed to intrauterine drug exposure in animal models, a finding which has not been confirmed in human beings.

Associated Anomalies

Ectopia cordis is frequently associated with other congential defects involving multiple organ systems. Ventricular Septal Defect and Tetralogy of Fallot are the most common intracardiac defects while omphalocele is the most common abdominal wall defect associated with ectopia cordis. There is some slim evidence that ectopia cordis may be related to Turner Syndrome. Chromosomal Anomalies like Trisomy 18 have also been observed in some children with ectopia cordis. In general, however, there is no recognizable cause for this conditon.

Treatment

Sadly, most cases of ectopia cordis result in stillbirth or death shortly after birth. A few case of ectopia cordis have been treated successfully, but this defect still poses the biggest challenge and rate of failure for pediatric cardiothoracic surgeons. Most cases are identified through routine prenatal ultrasound. When a case is suspected, the mother will be referred to a pediatric or fetal echocardiologist who will confirm the diagnosis. Attempts of surgical correction have been largely unsuccessful because of the extent of the associated anomalies. Surgical management includes immediate covering of the exposed heart and abdominal contents with a silastic prosthesis, as well as full evaluation and correction of any intracardiac defects prior to replacement of abdominal contents. The procedure often fails secondary to kinking of the great vessels or mechanical compression of the heart resulting in decreased cardiac output. Advances in the fetal ultrasound techniques have aided in early recogniton of such anomalies and termination of pregnancy prior to viablility should be considered and discussed with parents.

Sources:-

1. Wikipedia
2. TheFetus. Net (Images)
3. WiseGeek
4. PUBMed Central (Images)
5. Interactive Cardio Vascular and Thorcacic Surgery (Images)
6. Journal of Indian Association of Pediatric Surgeons
7. Humpath.com (Images)
8. BioPortifolio.com (Images)
9. Home and Garden WebShots.com (Images)
10. Childrens hospital of Wiscosin
11. Medical Dictionary (For definitions of medical terms)

Filed under: Ectopia Cordis - A rare congenital malformation, Medical World , Ectopia Cordis