Address correspondence to: Pamela Crum, RDMS, RDCS, (pam_crum@hotmail.com) Women’s Health Alliance of Nashville and Vanderbilt University Medical Center ¶Dept. of Pediatric Cardiology, §Dept. of Pathology.

Synonyms: L-transposition and atrioventricular discordance with ventriculoarterial discordance.

Definition: Right atrium and left atrium are connected to the morphologic left and right ventricle, respectively, and the great arteries are transposed.

Prevalence: 0.4 to 0.5% of infants with congenital heart disease or 0.2:10,000 live births⁷.

Etiology: There is no substantial evidence that heredity is an important role in corrected transposition of the great arteries. Multifactorial.

Pathogenesis: The ventricles are inverted and outflow tracts are parallel to one another. Either right-to-left and left-to-right shunts or a second anatomic anomaly leads to functional reversal of the malrotation.

Associated anomalies: Ventricular septal defects, pulmonary stenosis, systemic atrioventricular valve abnormalities, malposition of the cardiac apex, rhythm disturbances, especially atrioventricular block.

Differential diagnosis: Double inlet left ventricle with L-transposition and double-outlet left or right ventricle with L-malposition, ventricular septal defect, tricuspid atresia with increased pulmonary blood flow.

Prognosis: Poor with associated cardiac anomalies.

Recurrence risk: For any cardiac anomaly: 2 to 5% after one affected child and 10 to 15% after two affected children.

Management: Before viability, termination may be offered. The vast majority of infants with corrected transposition of the great arteries have repairable lesions and would be expected to survive into adulthood unless other associated lesions preclude survival. Appropriate counseling directed toward the specific associated lesions should be undertaken so that an informed decision regarding continuation or termination of pregnancy can be made by the family. Delivery should take place in a tertiary care center where pediatric cardiologists are immediately available.

MESH Transposition of great vessels BDE 0540 ICD9 745.12 CDC 745.120

Introduction

Congenital heart disease occurs with an incidence of 60 to 80 per 10,000 live births². We present a second trimester fetus diagnosed with corrected transposition of the great arteries, ventricular inversion and hypoplastic left-sided ventricle.

Case report

A 29-year-old G₃P₀₀₁₁ woman was referred for ultrasound evaluation at 23 weeks for a suspected hypoplastic left heart. The patient had previously delivered one term child by low transverse cesarean section and had spontaneously aborted a subsequent child at 8 weeks gestation. The mother was a smoker who denied use of alcohol or other drugs and related no family history of congenital anomalies. She had received prenatal care since the 4th week of gestation. An ultrasound examination revealed a pregnancy at 22 weeks with a complex cardiac anomaly (fig. 1-3) that was thought to represent ventricular inversion (absence of the moderator band in the anterior ventricle, and smooth trabeculation of the ventricle) with transposition of the great arteries (great vessels arising side-by-side) and possible interrupted aortic arch with a severely hypoplastic right ventricle position to the left and posterior to the anterior ventricle. In view of the poor prognosis, labor was induced and a stillborn infant was delivered.

Figure 1: Four chamber view of the heart. The axis of the heart is abnormal. The right-sided and anterior ventricle (LV) is smooth-walled and does not demonstrate a moderator band. The posterior ventricle (RV) is markedly hypoplastic. A=enlarged atrium with widely patent foramen ovale.

Figure 2: Outflow from the right-sided left ventricle. Note the large pulmonary artery.

Figure 3: Two views of the great vessels. Note the prominent ductal arch (left image) and the coarctation , (originally interpreted as an aortic interruption). The great vessels originate side-by-side (second image).

Autopsy

The autopsy revealed the body of a premature male infant weighing 650g. The head was normocephalic and atraumatic. The fontanels were soft, and the cranial sutures were widely open. No epicanthic fold was present, and the nares were patent. The external ears had the usual helical presentation and were not low set.

The lungs were pale pink, and no tracheoesophageal fistula was present. The bronchi and pulmonary vessels were patent. The right lung had three lobes, and the left lung had two lobes. The pleural surfaces were smooth and glistening.

The heart weighed 3.5g. The epicardial surface was smooth, and the myocardium was pale upon sectioning. The systemic venous return was to a right-sided, morphologic right atrium (fig. 4-8), which emptied through a broad, amorphous valve into a large, smooth-walled, anterior and right-sided ventricle.

Figure 4: Anterior view with the heart turned rightward. Note the preductal coarctation of the aorta. The brachiocephalic vessels originate proximal to this.

Figure 5: Smooth walled opened right-sided ventricle with a left ventricle morphology. Note the atretic AV valve.

Figure 6: Perimembranous VSD illustrated by passage of a probe from the left-sided into the right-sided ventricle.

Figure 7: Posterior aspect of the heart and lungs with opened left atrium. A probe passes through the atrial septal defect.

Figure 8: Small left-sided ventricular chamber with outflow to the anterior aorta.

The outflow from this ventricle was to a posterior pulmonary artery, with subpulmonic stenosis which gave way to a widely patent pulmonary artery and patent ductus arteriosus supplying the descending aorta.

The pulmonary venous return is to the morphologic left atrium, from which the outflow is to the right atrium by way of a patent foramen ovale, as there was atresia of the left-sided atrioventricular valve. The left-sided ventricle was hypoplastic, and any flow it may have received was from the right-sided ventricle by way of a small, perimembranous ventricular septal defect. The outflow from the left-sided ventricle was through an anterior aorta which had a preductal coarctation. The brachiocephalic vessels arose from the aorta proximal to the ductus arteriosus.

In summary, the heart was found to be in atrial situs solitus with corrected transposition of the great arteries. Associated anomalies included a hypoplastic left-sided ventricle, atresia of the left-sided atrioventricular valve, a perimembranous ventricular septal defect, preductal coarctation of the aorta and subpulmonic stenosis. The ductus arteriosus and foramen ovale were patent.

Discussion

History

The first description of a case of corrected transposition of the great arteries was by Theremin in 1895^3,13. Harris and Farber classified this type of case theoretically in 1939^3,14. In 1975, Van Praagh et al used the term "anatomically corrected malposition of the great arteries"^3,15.

Embryology

The embryological defect in corrected transposition is an abnormal rotation of the bulboventricular loop. Corrected transposition in visceral-atrial situs solitus develops when the primitive heart tube, or bulboventricular loop, loops to the left instead of to the right. This is associated with the lack of spiral rotation of the truncoconal septum⁵. The aorta is connected to the morphologic right ventricle, and the pulmonary artery is connected to the morphologic left ventricle. The ventricles are attached to the anatomically anchored and normally positioned atria, making this abnormality functionally corrected^5,11.

Associated anomalies

The most commonly associated anomalies of hearts with congenitally corrected transposition of the great arteries include

• ventricular septal defects,

• pulmonary outflow tract obstruction,

• dysplasia and displacement of the left or systemic atrioventricular valve,

• or a combination of these associated lesions⁸.

The frequency of ventricular septal defect has been reported as being as high as 80%, and pulmonary stenosis associated with the ventricular septal defect was also 80%. The most common defect is perimembranous and is found in a subpulmonary position⁷.

Either valvular or subvalvular pulmonary outflow tract obstruction is reported to occur in 30 - 50% of corrected transposition cases⁷. Also, commonly seen pathology is dysplasia of the tricuspid valve, with or without a displacement of the septal or posterior leaflets (Ebstein"s anomaly)¹.

Any cardiovascular lesion or combination of lesions can occur with corrected transposition. Additional anomalies include: atrial septal defect, patent ductus arteriosus, subaortic stenosis, coarctation and interruption of the aortic arch, aortic atresia, straddling atrioventricular valves, hypoplasia of one ventricle and pulmonary valvular atresia⁷.

Prognosis

In the absence of any additional cardiac defect, corrected transposition of the great arteries could be asymptomatic even through adulthood. However, the frequency of other intracardiac defects associated with corrected transposition of the great arteries can cause significant symptoms or mortality¹. Even without surgery, the patients may develop atrioventricular dissociation or tachyarrhythmias. Sudden unexpected death associated with preexisting complete atrioventricular block can occur⁷.

Obstetrical management

If the diagnosis is made before fetal viability, the option of pregnancy termination may be considered. A careful search for associated cardiac and extracardiac anomalies is recommended. Serial exams are indicated to monitor fetal growth, the development of hydrops and to detect fetal demise. Early delivery offers no advantage except in case of hydrops. Delivery in a tertiary care center where a pediatric cardiologist is immediately available is a must¹.

Treatment

The appropriate medical and surgical treatment will depend upon the clinical manifestations of associated lesion, dysrhythmias, and conduction disturbances. Ventricular septal defect, pulmonary outflow tract obstruction and systemic atrioventricular valve insufficiency account for most open heart operations in patients with corrected transposition.

Repair of the ventricular septal defect with a patch sutured on the left side of the septum is a technique now being used to avoid the atrioventricular conduction system which lies on the right side of the septum⁷.

The pulmonary outflow tract obstructions easily corrected by conventional techniques are pulmonary valvular stenosis, pulmonary band, and sub-pulmonary redundant tissue. However, with severe subpulmonary stenosis, the stenosis is bypassed with an external homograft or valved conduit⁷.

Clinically significant systemic atrioventricular valvular insufficiency further complicates cardiac surgery for corrected transposition of the great arteries. It may be necessary to repair or replace the atrioventricular valve, increasing the risk of the procedure. An approach other than complete repair may be necessary⁷.

In 1970, Friedberg and Nadas estimated survival rates to be 40% at 1 year of age and 30% at 10 years of age. Since then, results or surgery have improved remarkably. Hwang et al recently reported survival rates of 78% after intracardiac repair of cardiac defects associated with corrected transposition of the great arteries in a group of 18 infants during a 4.5 year follow-up period⁸. McGrath et al have given survival rates for one month, one year and ten year intervals after cardiac repair in patients with atrioventricular connections. Among 99 patients with discordant atrioventricular connections, the survival rates were 86%, 75%, and 68%, respectively¹².

References

1. Romero R, Pilu G, Jeanty P, et al. Prenatal diagnosis of congenital anomalies. Appleton and Lange 1988;164-166.

2. Veille JC, Mahowald MB, Sivaboff M. Ethical dilemmas in fetal echocardiography. Obstet Gynecol 1989;73:710-4.

3. Rittenhouse EA, Tenckhoff L, Kawabori I, et al. Surgical repair of anatomically corrected malposition of the great arteries. Ann Thorac Surg 1986;42:220-228.

4. Pasquini L, Sanders SP, Parness I, et al. Echocardiographic and anatomic finding in atrioventricular discordance with ventriculoarterial concordance. Am J Cardiol1988;62:1256-62.

5. de la Cruz MV, Arteaga M, Espino-Vela J, et al. Complete transposition of the great arteries. A study of 60 cases. N Engl J Med 1970;282:1053.

6. Allwork SP, Bentall HH, Becker AE. Congenitally corrected transposition of the great arteries. Morphologic study of 32 cases. Am J Cardiol 1976;38:910-923.

7.Freedom RM, Dyck JD. Congenitally corrected transposition of the great arteries with heart disease in infants, children, and adolescents. Including the fetus and young adults. Baltimore: Williams & Wilkins, 1995; 1227-1245.

8. Freedom RM, Benson LN. Congenitally corrected transposition of the great arteries. In Freedon RM, Benson LN, Smallhorn JF (Eds): Neonatal heart disease. London Springer-Verlag, 1992;523-539.

9. Kleinman CS, Donnerstein RL, Devore GR, et al. Fetal echocardiography for evaluation of in utero congestive cardiac failure: a technique for study of nonimmune hydrops. N Engl J Med 1982;306:568.

10. Scheibler GL, Edwards JE, Burchell HB, et al. Congenital corrected transposition of the great vessels: a study of 33 cases. Pediatrics 1961;27:851.

11. Friedberg DZ, Nadas AS. Clinical profile of patients with congenital corrected transposition of the great arteries. A study of 60 cases. N Eng J Med. 1970;282:1053-1059.

12. McGrath LB, Kirklin JW, Blackstone EH, et al. Death and other events after cardiac repair in discordant atrioventricular connection. J Thorac Cardiovasc Surg 1985;90:711-728.

13. Theremin E. Etudes sur les affections congenitales du coeur. Paris: Asselin et Houzeau, 1985;83.

14. Harris, JS, Farber S. Transposition of the great cardiac vessels with special reference to the phylogenetic theory of Spitzer. Arch Pathol 1939;28:427.

15. VanPraagh R, Durnin RE, Jockin H, et al. Anatomically corrected malposition of the great arteries (S, D, L). Circulation 1975;51:20.

16. Hoffman JIE, Christianson R. Congenital heart disease in a cohort of 19, 502 births with long-term follow-up. Am J Cardiol 1978;42:641-9.

Originally published in The Fetus in 1994, Posted 6/1999