Association of Atrioventricular Valve Atresia

with Single Ventricle, Truncus Arteriosus

Conununis and Transposition

A Basic Reorientation in the Approach to the Definition of Congenital Heart Defects

Jami G. SHAKIBI, M.D., F.A.C.C.,* Iraj ARYANPUR, M.D., F.A.C.C.,* Iraj NAZARIAN, M.D., F.C.A.P.,* and Bijan SIASSI M.D., F.A.C.C.*

SUMMARYA heart specimen is presented which showed a rare combination of

atrioventricular valve atresia with single ventricle, truncus arteriosus communis with an anteriorly placed trunk, ie transposition. Because of the problems involved in the classification of this heart, the types of single ventricle are revised with particular attention to the rare cases of atrioventricular valve atresia and single ventricle reported in the litera-ture. Also the rare type of truncus arteriosus communis with trunco-atrioventricular valve discontinuity is excluded from the so-called trans-position complexes, and properly classified as a form of truncus. The literal meaning of transposition is stressed and it is urged to approach congenital heart defects in a purely anatomic sense with definition of each segment as accurately as possible. Thus the present confusion in terminology and further plethora of new terms are avoided.

Additional Indexing Words: Congenetal heart disease Mitral atresia Common ventricle

TUDYING rare forms of congenital heart defect may help shed light on the pathogenesis of various forms of such defects. It is also important

in confirming or challenging the concepts, used in everyday practice of

pediatric cardiology. The purpose of this report is to describe in detail a rare type of congenital heart defect which showed an association of atresia of the atrioventricular valve and single ventricle, and truncus arteriosus com-munis with an anteriorly placed aorta, the so-called truncus transposition.1)

From the Departments of Pediatric Cardiology* and Pathology**, Queen Pahlavi Cardiovascular renter, Teheran, Iran.

This work was partly supported by the general research fund of the Queen Pahlavi Cardio-vascular Center.

Reprint requests to: Jami G. Shakibi, M.D., Queen Pahlavi Cardiovascular Center, PO Box 33-423, Shemiran, Teheran, Iran.

Received for publication October 11, 1977.

346

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APPROACH TO CONGENITAL HEART DEFECTS 347

Because of the problems involved in the classification of this heart according to the conventional guidelines, we propose a modified classification for single ventricle and transposition of the great arteries. Also we will reconsider the anatomy of truncus arteriosus communis and stress the presence of the trunco-atrioventricular valve discontinuity as a rare form of this defect. Our main

proposal is to base all definitions and diagnoses (anatomic, as well as angio-cardiographic) on purely observed facts, rather than striving to make the observed facts to conform to hypothetical embryologic or phylogenetic de-ductions. We will therefore avoid embryologic inferences and phylogenetic comparisons for explanation of the anomalies observed. As since more than 100 years ago, numerous and elaborate embryologic, phylogenetic and onto-

genetic explanations for genesis of congenital heart defects have been pro-posed,2)-9) we believe that further speculations are superfluous, until elaborate and critical methods for embryologic and teratogenic research are developed.

CASE HISTORY

MMH77-968: This 7 year-old-boy had been cyanotic since birth. He had dyspnea on exertion, shortness of breath, and squatting. There was a history of hypoxic spells up to 4 years of age. Physical examination revealed a deeply cyanotic boy with clubbing of the finger- and toe-nails. His weight was 16Kg, his height was 106cm. The pulse rate was 100/min and the respiratory rate was 30/min. His chest was clear on auscultation. Examination of his heart revealed no heaves or thrills, and the point of maximum impulse was felt at the fifth right intercostal space. The first heart sound was increased in intensity. A systolic ejection click was pre-sent at left sternal border. The pulmonic component of the second heart sound was absent. A grade II short systolic ejection murmur was present at the right sternal border. The liver edge was palpable on the right side. The peripheral pulses were of good quality and the rest of the physical examination was normal. The elec-trocardiogram showed sinus tachycardia with a rate of 120/min, QRS axis was at 20 degrees. The P axis was at 60 degrees. The precordial leads revealed right ventricular hypertrophy. The chest roentgenogram showed situs solitus, and dextro-cardia. The aortic arch was right-sided and the pulmonary vascular markings were reduced. His hemoglobin was 20.3Gm.% and his hematocrit was 73%.

The patient underwent cardiac catheterization and angiocardiography. Syste-mic venous saturation was low (63%). Right and left atrial saturations were 74 and 78% respectively, and the mean right and left atrial pressures were equal to 9mmHg. Left pulmonary venous blood was 96.8% saturated. Aortic blood saturation was 71% with PaO2 equal to 35mmHg. Pullback aortic and ventricular pressures were 72/48 (mean=55)mmHg and 72/0mmHg respectively. Angio-cardiograms were obtained in the ventricle in anteroposterior and lateral positions. Diagnosis was situs solitus, dextrocardia, single ventricle (?left) with an outflow chamber, pulmonary atresia, patent ductus arteriosus, large atrial septal defect (? secundum type), and transposition of the great vessels. As the pulmonic valve could not be accurately located, d-transposition versus l-transposition could not be decided.

348 SHAKIBI, ARYANPUR, NAZARIAN, AND SIASSI Jap. Heart J. May, 1978

Because of the low PaO2 and patient's disability a right Blalock-Taussig shunt was

performed. Following the operation the patient's PaO2 did not improve. The shunt was revised and a clot was removed from the site of the anastomosis. De-spite an adequate shunt, the patient's oxygenation was poor and he could not be we-

aned off the respirator. Each attempt at discontinuation of the assisted ventilation

caused rapid deterioration with reduction of PaO2 and massive pulmonary edema. Eventually it was decided to ligate the left-sided patent ductus arteriosus, which was

performed on the sixth postoperative day. The patient failed to improve and nee-ded continuous assisted ventilation. Digitalis, diuretics, and fluid restriction were

of no avail to relieve pulmonary edema. Further attempts to study the patient were curtailed because of pseudomonas pneumonia and sepsis. The patient expired

15 days after the operation.

DESCRIPTION OF THE SPECIMEN

The specimen consisted of the heart and lung complex removed through

the surgical incision, as complete postmortem examination was refused by the

parents. Both lungs had 2 lobes. The left lung had the lingular lobe, which was not present on the right side. The heart was large and its apex pointed

to the right. Superior and inferior venae cavae entered an anatomically

right atrium which was located on the right side. The ostium of the coronary

sinus was normally positioned below the rim of the fossa ovalis. A large se-

cundum atrial septal defect was present with distinct crista terminalis and a

defective septum secundum. All pulmonary veins entered the left atrium

Fig.1. This figure shows the right atrium, the atretic right atrioventric-ular valve (mitral) (AVV), and the stenotic ostium of the right lower pulmo-nary vein (PV). Cross-sections on the left part of the figure failed to disclose a hypoplastic ventricle or ventricular septum (arrows). The heads of 2 probes are seen in the right ventricular cavity.

Vol.19 No.3 APPROACH TO CONGENITAL HEART DEFECTS 349

Fig.2. This figure shows a coarsely trabeculated single right ventricle with tricuspid (TV) and truncal valves (TR) cusp discontinuity. The valves are separated from each other by a thick muscular band, ie crista supraventric-ularis (CS). The coronary ostia (CO) and 3 papillary muscles (1, 2, 3) are also shown.

Fig.3. This figure shows the truncus arteriosus communis with truncal valve-cusps (TR) and coronary ostium (CO) in the lower part. The white triangle points to the ostium of the left pulmonary artery (LPA), which was ligated (L). Two probes on the right side are in the right innominate (IA) and right pulmonary artery (RPA).

350 SHAKIBI, ARYANPUR, NAZARIAN, AND SIASSI Jap. Heart J. May, 1978

except the right lower pulmonary vein which entered the right atrium via a stenotic ostium. The right subclavian artery was anastomosed with this vein (the cause of intractable pulmonary edema after the shunt operation)

(Fig.1). The left atrium was located on the left side. The right atrioven-tricular valve was atretic, thus all the systemic and part of the pulmonary venous blood had to cross the atrial septal defect to the anatomically left atrium

(Fig.1). The left atrium communicated with an anatomically right ventricle (coarse trabeculations, crista supraventricularis, an outflow chamber, papil-lary muscle of the conus and 3 papillary muscles) via a normal tricuspid valve

(Fig.2). Despite atresia of the atrioventricular valve neither an atretic ven-tricle, nor a ventricular septum could be detected (Fig.1). The single right ventricle communicated with a large vessel having 3 normal semilunar valve cusps (Fig.2). This vessel gave branches to the head and neck, the lungs, and the heart. The right pulmonary artery was interrupted about 1cm distal to its take-off from the single trunk. The left pulmonary artery had been ligated (thought to be patent ductus arteriosus). There was no ductus arteriosus (Fig.3). A distinct muscular band (crista supraventricularis) separated the tricuspid and the atretic atrioventricular valves from the truncal valve leaflets (Fig.2). The truncal valve cusps were anteromedial antero-lateral, and posterior in position, with 2 coronary arteries arising from the anterolateral and posterior sinuses. The right coronary artery coursed in the right atrioventricular groove to the right and descended on the right postero-superior margin of the heart toward the apex. The left coronary artery coursed posteriorly and inferiorly and gave off 2 branches, one returning anteriorly in the left atrioventricular groove and the other descending toward the apex on the posterior aspect of the ventricle.

DISCUSSION

Thus we have presented a heart with distinctly unusual features, namely association of single ventricle with right atrioventricular (mitral) atresia and a truncus arteriosus communis with anteriorly placed trunk and a subtruncal conus, separating the truncal valve cusps from the atrioventricular valves. We would like to consider and discuss the following problems:

I. Association of single ventricle with atrioventricular valve atresia.II. The trunco-atrioventricular valve discontinuity in truncus arteriosus

communis.III. The definition of transposition of the great arteries and classifica-

tion of the relative positions of the aorta and pulmonary artery.

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APPROACH TO CONGENITAL HEART DEFECTS 351

I. Association of single ventricle with atrioventricular valve atresia: Single ventricle is classically defined as a single or common ventricular

chamber, in which both atrioventricular orifices, either separated or fused, or a common atrioventricular canal enter. The ventricular sinus may have the anatomic characteristics of the left or right ventricle or it may be of the

primitive, undifferentiated type.10)-19) Thus by definition cases with atresia of one atrioventricular orifice have been excluded from this entity. Quero17),18) reported 2 hearts which had single ventricle with atresia of atrioventricular orifice. Both cases reported had a single left ventricle,12) with a normal mitral valve and atresia of the left atrioventricular valve orifice (ie tricuspid atresia). These cases similar to ours, are indicative of the fact that single ventricle does indeed exist with atresia of one of the atrioventricular valves, and its rarity does not warrant its exclusion from the classification of single ventricle. In order to make the diagnosis of single ventricle with atresia of one atrioven-tricular valve, we maintain that single ventricle should be defined in its purest anatomic sense as only one ventricular sinus without evidence of the presence of another atretic ventricle or ventricular septum with or without an outflow chamber. Thus this definition excludes cases of classic tricuspid or mitral atresia which do present an atretic ventricular sinus and a well-formed but small ventricular septum. The anatomic characteristics of the latter anomaly have been recently presented in detail.19) Thus our criterion differs from that

proposed by Quero,17) according to which in a single ventricle with atresia of one of the atrioventricular valves the topographically homologous ventricle should be present. He also stated18) that instead of mitral or tricuspid atresia he preferred to use the term "atrioventricular orifice atresia" as the terms "mitral" and "tricuspid" became meaningless in these cases. Thus ac-cording to these arbitrary criteria, the 2 cases of single left ventricle had one normal mitral valve plus an atretic right-sided atrioventricular valve. One wonders what kind of valve does he assume atretic? If it is tricuspid, then according to his homologous ventricular theory the right ventricle should be present, while he has identified the major chamber in his 2 hearts as left ventricle. On the other hand one cannot assume both valves to be mitral valves, since this is theoretically impossible. If we do not name the atrioventricular valves, the homologous ventricle could be right or left as they cannot be distinguished from each other on the basis of their atrioven-tricular valves. A comment is in order here regarding the cases of double inlet left ventricle. De la Cruz and Miller,20) and Mehrizi,21) described speci-mens which showed an anatomic left ventricle receiving both mitral and tricuspid valves. They considered that most cases of Van Praagh's single left ventricle, Type A, were double inlet left ventricle. Our critical review

352 SHAKIBI, ARYANPUR, NAZARIAN, AND SIASSI Ja Heart J. 1978

Table I. Anatomic Types of Single Ventricle

See text for definition of single ventricle and double inlet left ventricle.

of their works makes us believe that one of de la Cruz's cases (case 1, specimen 1067) was truly a double inlet left ventricle, whereas the second case was a single left ventricle11) which received both atrioventricular valves. We thus exclude cases of double inlet left ventricle from the category of single ventricle as does Quero17),18) and maintain that in order to make the diagno-sis of double inlet left ventricle, in addition to the entrance of 2 atrioventricular valve orifices into the anatomic left ventricle, a right ventricular sinus (not outflow tract) no matter how diminutive should be present. Thus we classify Lev's primitive ventricles with straddling and displaced atrioventricuilar orifices22) as double inlet left ventricle. In our opinion single ventricle should be defined as an anatomically single ventricular chamber with or without an outflow chamber, giving rise to the pulmonary artery, aorta or a single trunk,13) it may have 2 separate atrioventriuclar valves or 1 common atrioventricular valve or 1 normal and 1 atretic valves. In any case there should be no remnant of the sinus of the other ventricle. In a pure anatomical sense we think one has to exclude types C and D of single ventricle of Van Praagh,12) because type C (undivided ventricles) can be called a huge ven-tricular septal defect,10) since both ventricular sinuses are present, and type D (absence of ventricular sinuses) and the so-called bulboventricular heart of Goor and Edwards,8) do not represent a single ventricle because none of the ventricular sinuses are present.23) In Table I we present the revised classifi-cation of single ventricle.

II. The trunco-atrioventricular valve discontinuity in truncus arteriosus com-munis:

The second remarkable feature of our specimen is trunco-atrioventricular valve discontinuity. Confusion exists concerning the truncal nature of this type of defect, with application of terms such as transposition type of truncus arteriosus communis.1) We believe that confusing transposition with truncus

Vol.19 No.3 APPROACH TO CONGENITAL HEART DEFECTS 353

is due to problems in definition of the former (see part III of this discussion). We define truncus arteriosus communis as a congenital malformation in which one great artery arises from the base of the heart and gives origin to the coronary, pulmonary and systemic arteries .24),25) In the purest form of definition and in agreement with Thiene,26) we believe there is a wide spec-trum of conal anatomies in truncus arteriosus communis and that lack of

growth of the conus in the usual type of this defect is not a causative factor in the genesis of truncus, rather it is a common developmental characteristic of this defect. The morphology of the ventricular outflow tract in truncus arteriosus communis is variable. The posterior wall of the truncus is usually in fibrous continuity with the truncal and the mitral and triucspid valves indicating that the embryonic conoventricular flange has undergone complete absorption.27),28) Rarely there is a muscular mass interposed bilaterally between the truncal valve and the atrioventricular valves. In some speci-mens such as ours a mass of muscular tissue interposed between the truncal and atrioventricular valves, resembling crista supraventricularis of the normal heart,26)-28) is present, pointing to the lack of absorption of subpulmonary conus. These observations point to the fact that the conal growth shows a wide spectrum in truncus arteriosus communis, and are in disaccord with the view propounded by Van Praagh et al1),29) that truncus arteriosus com-munis always results from atresia of the subpulmonary infundibulum. Ac-cepting this hypothesis is not only inconsistent with the observation of cases of truncus with trunco-atrioventricular valve discontinuity, but it also makes classification of the truncus arteriosus communis difficult. Van Praagh1) had great difficulty in defending his classification of truncus arteriosus without ventricular septal defect (ie aorto-pulmonary window) as a form of truncus. As a matter of fact all this difficulty arises because of the original belief that truncus arteriosus is developmentally due to atresia of the subpulmonary infundibulum. Whereas we now maintain in agreement with Van Mierop and Gessner30) that in truncus arteriosus communis 3 components may be at fault, ie the conal septum, the truncal septum and the aortopulmonary septum. Referring to Thiene's paper26) one is confronted with no difficulty to justify Van Praagh's belief that aortopulmonary window is actually a form of truncus arteriosus communis. Thus very concisely, the presence of trunco-atrioventricular valve discontinuity points to the fact that truncus arteriosus communis is essentially due to a lack of septation of the outflow tract of the heart, while the left and right canal free wall may or may not be present.27)

III. The definition of transposition of the great arteries and classification of the relative positions of aorta and pulmonary artery

354 SHAKIBI, ARYANPUR, NAZARIAN, AND SIASSI Jap. Heart J. May, 1978

A cursory review of the current literature in pediatric cardiology leads one to the inevitable conclusion that there exists a confusion regarding the nomenclature of the relative positions of the great arteries.31)-34) This con-fusion has been produced primarily by a lack of agreement on certain basic

points. A brief discussion will put our view in perspective. Abbott35) defined transposition of the great arteries in this manner: "Transposition of great vessels is defined as an alteration in the position of the two great arteries, relative to the ventricles of the heart [part one of definition], or to each other at their origin [part two of definition] so that they either spring from reversed ven-tricles, the aorta from the right and the pulmonary artery from the left chamber

(complete transposition) or from the ventricle to which they normally belong, but in reversed relationship". The inadequacy of this definition (part 2) soon became evident, so that Harris and Farber5) stated "in certain cases the definition of complete transposition must be supplemented by the words: and an alteration in the anteroposterior relationships of the great vessels, either at the ventricular insertion or in their spiraling." This view was further strengthened by Keith,36) and Van Praagh's32) classical works on transposition, maintaining that transposition of the great arteries was due to an abnormality in the conus portion of the heart. Thus in everyday routine practice of

pediatric cardiology the term transposition came to be known almost always synonymous with an anterior aorta and a posterior pulmonary artery. How-ever, it became evident that transposition as defined to the relative position of the great arteries was not necessarily always transposition,9),37) i.e., the great arteries could originate from the wrong ventricles with variable anteroposterior relationships. These conflicting findings were aptly reviewed by Van Praagh,17) who came to the inevitable final conclusion that transposition should be de-fined, accurately and literally, ie "trans=across and ponere=to place". Thus "transposition of great arteries is present if both great arteries are placed across

(transponere) the ventricular septum: aorta arising above the morphologically right ventricle and pulmonary artery originating above the morphologically left ventricle." This definition of transposition is in agreement with part 1 of Abbott's definition. Once this view held, one is led to several conclusions and a necessity for certain redefinitions:

1. The relative spatial positions of the great arteries should be described in single ventricle, as there is no ventricular septum. Thus application of the term "transposition of the great arteries" in single ventricle should be avoided.

2. If tansposition is defined in its purest literal sense of the term, cases of "posterior" transposition,9),33) should not be redefined with additional term of "posterior", as transposition does not necessarily mean an anterior aorta.

Vol.19 No.3 APPROACH TO CONGENITAL HEART DEFECTS 355

Fig.4. Relative positions of the roots of aorta and pulmonary artery. Each position may have 3 types, ie pulmonary artery superior, aorta superior or both aorta and pulmonary artery on the same level (modified scheme of Von Rokitansky).

3. The use of terms such as "transposition-type of truncus arteriosus

communis",4) in classifying cases such as ours and those of Thiene44) become unnecessary, because these cases are truly rare forms of truncus and the term "transposition" has no particular meaning in their definition or classification .

4. The literal definition of transposition leads us to the last conclusion

that in order to describe individual instances of relative positions of the great

arteries, one should define the relative positions rather than come up with new terms. Already terms such as d-transposition, l-transposition, d-mal-

position, l-malposition, posterior transposition, p-transposition, and partial distortion37) have appeared in the literature. A look at Fig.4 shows that the roots of aorta and pulmonary artery could maintain at least 24 hypothetical

positions (regardless of their relations to the ventricles). Thus one should await a plethora of new terms with the inevitable future description of various

rare types of defects. Therefore we suggest in agreement with Van Praagh,7)

to define transposition of the great arteries in its purest literal and anatomic sense. We also suggest continued use of the practically useful terms of d-

transposition and l-transposition in their most typical cases. Apart from these

2, we suggest that all other relative positions of the great arteries should be defined in their anatomic sense and further invention of new terms and re-

definitions of the present terms (posterior transposition, side-by-side transposi-

tion, distortion) to be avoided. We suggest to approach cardiac defects an-

atomically and angiocardiographically in a purely descriptive fashion, de-scribing every segment of the heart and great vessels most accurately and

356 SHAKIBI, ARYANPUR, NAZARIAN, AND SIASSI Jap. Heart J. May, 1978

avoiding to make the observed facts to conform to the embryologic and

phylogenetic deductions.44) A purely anatomic description of anomalies with the least possible usage of terms makes a logical diagnosis and therefore sur-

gical decision easier and avoids further confusion. To reconfirm our view a study of hypothetical sketches (available upon request) shows that 4790 different types of anomalies involving the ventricles, great arteries, and atrio-ventricular valves are possible, thus making definition of anatomy by terms almost impossible.

REFERENCES

1. Van Praagh R: Classification of truncus arteriosus communis. Am Heart J 92: 129, 19762. Von Rokitansky CF (Ed): Die Defecte der Scheidewande des Herzens. W Braumuller

Vienna, 18753. Spitzer A: in Handbuch der speziellen pathologischen Anatomic and Histologic (ed

Henke F, Lubarsch O), Julius Springer, Berlin, Vol2, 1. 1094, 19244. Pernkopf E, Wirtinger W: Die Transposition der Herzostien: ein Versuch der Erklarung

dieser Erscheinung ; die Phoronomie der Herzentwicklung. Z Anat Entwickl 100: 563, 19335. Harris JS, Farber S: Transposition of the great cardiac vessels. Arch Path 28: 427, 19396. Lev M, Saphir O: A theory of transposition of the arterial trunks based on the phylogenetic

and ontogenetic development of the heart. Arch Path 39: 172, 19457. Van Praagh R: Do side by side great arteries merit a special name? Am J Cardiol 32: 874,

19738. Goor DA, Edwards JE: The spectrum of transposition of the great arteries, with specific re-

ference to the developmental anatomy of the conus. Circulation 43: 406, 19739. Wilkinson JL, Arnold R, Anderson RH et al: Posterior transposition reconsidered. Brit

Heart J 37: 757, 197510. Lev M, Liberthson RR, Kirkpatrick JR et al: Single ventricle. Circulation 39: 577, 196911. Van Praagh R, Ongley PA, Swan HJC: Anatomic types of single or common ventricle in

man. Morphologic and geometric aspects of 60 necropsied cases. Am J Cardiol 13: 367, 1964

12. Van Praagh R, Van Praagh S, Vlad P et al: Diagnosis of the anatomic types of single or common Ventricle. Am J Cardiol 15: 345, 1965

13. Anselmi G, Armas SM, De la Cruz MV et al: Diagnosis and classification of single ventricle. Report on 17 cases with anatomoembryologic discussion. Am J Cardiol 21: 813, 1968

14. Edwards JE: Congenital malformations of the heart and great vessels. In: Pathology of the Heart (Ed Gould SE), Charles C Thomas Publ, Springfield, p260, 1960

15. Elliott LP, Anderson RC, Edwards JE: Common cardiac ventricle with transposition of the great vessels. Brit Heart J 29: 289, 1964

16. Harley HRS: Embryology of cor triloculare biatrium with bulbar (rudimentary) cavity. Guy's Hosp Rep 107: 116, 1958

17. Quero M: Atresia of the left atrioventricular orifice associated with a Holmes heart. Circula-tion 42: 739, 1970

18. Quero M: Coexistence ofsingle ventricle with atresia of one atrioventricular orifice. Circula-tion 46: 494, 1972

19. Anderson RH, Wilkinson JL, Arnold R et al: Morphogenesis of bulboventricular malforma-tions: II-Observations on malformed hearts. Brit Heart J 36: 948, 1974

20. De la Cruz MD, Miller LB: Double-inlet left ventricle. Two pathological specimens with comments on the embryology and its relation to single ventricle. Circulation 37: 249, 1968

Vol.19 No.3 APPROACH TO CONGENITAL HEART DEFECTS 357

21. Mehrizi A, McMurphy DM, Ottensen OE et al: Syndrome of double inlet left ventricle. Angiocardiographic differentiation from single ventricle with rudimentary outlet chamber. Bull Johns Hopkins Hosp 119:255, 1966

22. Liberthson RR, Paul MH, Muster AJ et al: Straddling and displaced atrioventricular orifices and valves with primitive ventricles. Circulation 43: 213, 1971

23. Mehrizi A, Rowe RD (ed): The Neonate with Congenital Heart Disease. WB Saunders Co, Philadelphia, p355, 1968

24. Calder L, Van Praagh R, Van Praagh S et al: Truncus arteriosus communis ; clinical, an-

giocardiographic and pathologic findings in 100 patients. Am Heart J 92: 23, 197625. Lev M, Saphir O: Truncus arteriosus communis persistens. J Pediat 20: 74, 194226. Thiene G, Bortologgi V, Gallucci V et al: Anatomical study of truncus arteriosus communis

with embryological and surgical consideration. Brit Heart J 38: 1109, 197627. Thiene G, Cucchini F, Pellegrino Pa: Truncus arteriosus communis associated with under-

development of the aortic arch. Brit Heart J 37: 1268, 197528. Khoury GH: Truncus arteriosus: a pathoradiologic study. Am J Cardiol 25: 109, 197029. Van Praagh R, Van Praagh S: The anatomy of common aorticopulmonary trunk (truncus

arteriosus communis) and its embryologic implication. A study of 57 necropsy cases. Am J Cardiol 16: 406, 1965

30. Van Mierop LHS, Gessner IH: Pathogenetic mechanism in congenital cardiovascular mal-formations. Prog Cardiovasc Dis 15: 67, 1972

31. Taussig HB, Bing RJ: Complete transposition of the aorta and a levoposition of the pulmo-nary artery. Am Heart J 37: 551, 1949

32. Van Praagh R, Vlad P, Keith JD: Complete transposition of the great arteries. In: Heart Disease in Infancy and Childhood, 2nd Ed, MacMillan Co, New York, p.682, 1967

33. Van Praagh R: Transposition of the great arteries. II-Transposition clarified. Am J Car-diol28: 739, 1971

34. Van Mierop LHS: Transposition of the great arteries. I: Classification or further confu-sion? Am J Cardiol 28: 735, 1971

35. Abbott ME: Congenital cardiac disease. in Modern Medicine. Osler W, 3rd ed, Vol 4,

p.720, 192736. Keith A: The Hunterian lecture on malformations of the heart. Lecture II. Lancet 2: 433,

190937. Angelini P, Leachman RD: Pulmonary artery originating from the left ventricle. Am J

Cardiol 32: 840, 197338. Anderson RH, Wilkinson JL, Gerlis LM et al: Atresia of the right atrioventricular orifice.

Brit Heart J 39: 414, 1977