ventricular inversion without transposition of the great

British HeartJournal, I970, 32, 292-303.

Ventricular inversion without transposition ofthe great vessels in situs inversusJorge Espino-Vela, Maria V. de la Cruz, Luis Muioz-Castellanos, Leandro Plaza,and Fause AttieFrom the Department of Paediatric Cardiology and the Department of Embryology, InstitutoNacional de Cardiologia, Av. Cuauhtemoc 300, Mixico 7, D.F. Mexico

A classification of one type of congenital malformation previously reported (de la Cruz et al.,I967) is based on the integration of an embryological theory for ventricular inversions with theembryological concepts of trunco-conal malformations (de la Cruz and da Rocha, I956). In thatclassification we consider that in each situs, either solitus or inversus ventricular inversions maybe associated with: (a) normally arranged great vessels (not transposed); (b) transposition of thegreat vessels; (c) persistent truncus arteriosus. The patients had ventricular inversion withouttransposition of the great vessels in situs inversus.

The correct anatomical diagnosis was not foreseen but the physiopathological diagnosis wascorrect: pulmonary ischaemia associated with septal defects. In one case these facts were substan-tiated by catheterization and by angiocardiographicfindings which led us to advise surgery. Haemo-dynamically isolated inversion of the ventricles is as severe a malformation as complete (not cor-rected) transposition of the great vessels. However, an operation of the anastomotic type betweena systemic vessel and the narrow pulmonary artery seemed justified in these cases, as a means toconvey more blood to the lungs and improve the saturation of the arterial blood. It was unsuccess-fully carried out in one patient.

The anatomical, radiological, and electrocardiographic features which might aid in the diagnosisare analysed.

The term 'corrected transposition' of thegreat arteries, implies two anatomical con-cepts: transposition of the great arteries andinversion of the ventricular chambers. There-fore, the designation does not emphasizewhat appears to be the most salient featureof such an entity, that is ventricular inversion(Walmsley, I93I; Abbott, I936; Liebowand McFarland, 1941; de la Cruz et al.,I959; de la Cruz, Polansky, and Navarro-L6pez, I962; Van Praagh et al., I964). Forthis reason, a new classification and nomen-clature was proposed by us in a recent paper(de la Cruz et al., I967). Ventricular inver-sion is the basis of the classification, eitherfor patients with situs solitus or with situsinversus; it may be associated with, (a)vessels which cross each other in space withan anteriorly placed pulmonary artery, i.e.without transposition of the great arteries(Van Praagh and Van Praagh, I966); (b)parallel vessels with an anteriorly placedaorta, i.e. transposition of the great arteries;and (c) persistent common truncus (Anselmiet al., I963).

Received 22 August I969.

The purpose of this paper is the analysisof two cases of ventricular inversion withouttransposition of the great arteries, apparentlythe most uncommon of the three possi-bilities described. Both were cases of situsinversus.

Case reportsCase I A ig-year-old girl, cyanotic from birth,suffered repeated hypoxic spells from 3 monthsuntil the age of 8 years. She had dyspnoea onmoderate exertion and greatly diminished physicalendurance. Physical examination disclosed a frailunderdeveloped young woman with arachnodac-tyly and an asymmetrical chest wall. The cardiacapical impulse was felt on the 4th right intercostalspace. Auscultation of the heart disclosed a softgrade 2/4 systolic murmur in the midpraecordialarea. The second 'pulmonary' sound was singleand reinforced. Blood pressure was 120/70 mm.Hg. The liver was percussed on the left side.The chest x-ray (Fig. ia) disclosed a slightly

enlarged heart with a wide pedicle. It had aprominent vascular segment on the right side,and another prominent segment on the leftcardiac border. The pulmonary circulation wasdecreased. The ventricle on the right was thoughtto be enlarged. The position of the cardiac apexwas not established clearly.

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Ventricular inversion without transposition of the great vessels in situs inversus 293

FIG. I Case r. Mirror-image dextrocardia and ventricular inversion without transposition ofthe great vessels. (a) Chest film. The apex is not clearly seen on either side. Notice the slightprominence of the aorta to the right and the prominence of what appears to be the 'pulmonary'segment on the left border of the heart. The vascularity of the lungs is slightly decreased.(b) Electrocardiogram which shows a negative P wave in lead I. Notice that VR is apredominantly positive complex, which would be unusual for a situs inversus but notfor theright-sided right ventricle which this case had (ventricular inversion). The sequence of theventricular complexes in the praecordial leads is that usually expected for normally placedventricles in the presence of right ventricular hypertrophy. (c) Diagrammatic representation show-ing the spatial relation of the great vessels, the cardiac chambers, the direction of the apex, and theposition ofthe liver. PA,pulmonary artery; Ao, aorta; LA, anatomically left atrium; RV, ana-tomically right ventricle; RA, anatomical right atrium; LV, anatomical left ventricle. (d) Externalaspect of the heart, of the great vessels and of the liver. PA, narrow pulmonary artery; Ao aorta.

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294 Espino-Vela, de la Cruz, Mufioz-Castellanos, Plaza, and Attie

TABLE Catheterization data

Saturation Pressures (mm. Hg)

Systolic Di D2 Mean

Superior venacava 17-25 560go

Rt. atrium I8 47 60-95 4Rt. pulmon-

ary vein 26-94 86-6o 8Lt. atrium 26-68 88oo 6Lt. ventr. I956 64-65 Io8 0 5 4Aorta I9-60 64 65 98 60 80

Hb 22-62 g./ioo ml., Hb capacity 30-31 vol. per cent,02 consumption 224 ml./min.

The electrocardiogram (Fig. ib) showed in-verted P waves in lead I and positive P wavesin VR. The sequence of the chest (praecordial)leads taken on the left side showed tall R wavesin Vi and rs complexes in V6.A tentative diagnosis was made of situs inver-

sus, congenital heart disease with right-to-left

shunt, and pulmonary stenosis. Cardiac catheter-ization and angiocardiography were performed(Table). The catheter entered the venous oranatomically right atrium placed on the left andventricular chamber. The aorta filled from thisventricle and was clearly posterior with respectto the narrow pulmonary artery which filledsimultaneously and crossed the aorta anteriorly,showing a normal relation of the great arteries,i.e. absence of transposition. It was concludedfrom these studies that there were large atrialand ventricular septal defects, an overridingaorta, and pulmonary infundibular stenosis. Thediagnosis of situs inversus, dextrocardia, andpossible tetralogy of Fallot with atrial septaldefect or AV comunis was made, and operationwas advised.A left-sided subclavian pulmonary anastomosis

was done. The patient developed ventricularfibrillation during the operation which was suc-cessfully treated. However, she died unexpectedlyon the fourth post-operative day.

NecropsyThe viscera were placed as pertains to situsviscerum inversus; the cardiac apex was directed

FIG. 2 Internal view of the cardiac cavities of Case i with mirror-image dextrocardia andventricular inversion without transposition of the great arteries. (a) The anatomical right atriumis placed on the left; notice the crista terminalis (CT), the pectineal muscles (PM), the sinus portion(SP). An arrow points to the connexion of the inferior vena cava (IVC) with this atrium. Thisatrium connects with the inflow tract of a ventricle which exhibits a smooth interventricularseptum in its upper two-thirds, characteristic of anatomical left ventricles. (b) The atrium placedon the right shows the smooth wall which characterizes the anatomical left atrium; notice theatrial septal defect (ASD). This cavity connects with the inflow chamber of the anatomically rightventricle placed on the right. (c) The ventricle placed on the right shows the features of theanatomical right ventricle; notice the crista supraventricularis (CS- V); a probe has been placed infront of it, within the stenotic infundibulum of the pulmonary artery (PA). The interventricularseptum is trabeculated. The aorta (Ao) emerges behind the crista, overriding the ventricular septum.

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to the right. The pulmonary artery was of smallcalibre (i of the size of the aorta). It originatedanteriorly with respect to the aorta crossing itfrom right to left and from the front to the back(Fig. ic and d). The aortic arch was locatedover the right bronchus (right-sided aorticarch). The left-sided atrial appendage wassmooth and bulging as seen in anatomically rightatrial appendages. The right-sided atrial appen-dage was small and irregular, as are anatomicallyleft atrial appendages.

Internally the left-sided atrium had the ana-

tomical features of a right atrium: there weretwo endocardial areas separated by the cristaterminalis; the posterior part was smooth (sinusportion) and it connected with the inferior venacava and the superior vena cava. The four pul-monary veins also entered this chamber; theanterior portion contained the pectineal muscles(Fig. 2a). This atrial chamber communicatedthrough a stenotic valvular orifice protected bytwo valvular leaflets with a ventricle whose innerseptal surface was smooth in its upper two-thirdsand trabeculated in its lower third. This ventriclehad two groups of papillary muscles and it lackeda crista supraventricularis. All of these featurespertain to an anatomical left ventricle (Fig. 2a).The atrium placed on the right was smooth andit had the morphological features ofthe anatomicalleft atrium. There was a large interatrial septaldefect of the fossa ovalis type with a fenestratedvalve (Fig. 2b). This chamber communicatedby means of an atrioventricular orifice havingthree valves with a right-sided ventricle which hada trabeculated septal surface. This ventricle hadnumerous trabeculae, an anterior papillarymuscle, and the crista supraventricularis with itsparietal and septal bands, which are the morpho-logical features of an anatomical right ventricle(Fig. 2b and c). The pulmonary artery arose infront of the crista supraventricularis. It had in-fundibular and orificial stenoses (Fig. 2c). Theaorta arose behind the crista overriding the ven-tricular septum; in the ventricular septum therewas an interventricular septal defect of the middlebasal type (Fig. 2d), i.e. absence of the parsmembranacea.

Diagnosis Situs inversus; mirror-image dextro-cardia; orificial stenosis of the left atrioventri-cular valve (mitral valve); ventricular inversionwithout transposition of the great vessels; inter-atrial septal defect; ventricular septal defect;total anomalous pulmonary venous connexionto the anatomical right atrium; orificial andinfundibular stenosis in a hypoplastic pulmonaryartery; dextroposition of the aorta; right-sidedaortic arch.

Case 2 A 4-year-old girl, cyanotic from birth,began squatting at the age of 2 years. She was

dyspnoeic on effort. Physical examination dis-closed a small frail cyanotic child. The cardiacapex was felt at the 4th left intercostal space.There wai a grade 2/4 systolic murmur at thethird and fourth left intercostal spaces next to

the sternal border; the second 'pulmonary'sound was soft. Blood pressure was IO1/70mm. Hg. The liver was percussed on the left side.The chest x-ray showed a grade I/4 cardio-

megaly. The cardiac apex was directed to the left.The gastric bubble was visualized on the rightside. The hilar vascular markings appeared almostnormal. There was a prominent vascular segmenton the right border of the heart which wasthought to be the ascending aorta; it was slightlyuncoiled. There was another prominent segmenton the left cardiac border which was thought tobe the pulmonary artery (Fig. 3a).The electrocardiogram showed a negative P

wave in lead I which was suggestive of atrialinversion (situs inversus). There were rsR com-plexes in VR and V3R, and rS complexes in V6.The electrocardiogram was suggestive of rightventricular hypertrophy, and left atrial and prob-able right atrial enlargement (Fig. 3b).The patient had convulsions following hypoxic

episodes which left neurological sequelae. Acerebral abscess was postulated. This was con-firmed and successfully treated surgically. Twomonths later the patient died during a severehypoxic spell.

NecropsyThe viscera were arranged in situs inversus.The cardiac apex was directed to the left. Thepulmonary artery was narrow (one-third the sizeof the aorta). It originated anteriorly with respectto the aorta crossing it obliquely from right toleft and from the front to the back (Fig. 3c andd). The aortic arch overrode the right bronchus.The atrial appendage loca'ted on the left wassmooth and bulging, the features usually seenin anatomically right atrial appendages. Theatrial appendage on the right was small andirregular as seen in normal anatomically leftatrial appendages. The internal aspect of theleft-sided atrium had the anatomical featuresnormally seen in right atria since it had twoportions which were separated by the cristaterminalis; the inner portion was smooth (sinusportion) and received the inferior and thesuperior vena cava; the outer portion had thepectineal muscles (Fig. 4a). There was no atrio-ventricular orifice in the floor of this atrium.The atrium placed on the right was smooth. Itreceived the 4 pulmonary veins, which is theanatomical feature of normal left atria (Fig. 4b).The interatrial septum showed a defect of thefossa ovalis type (Fig. 4a). This atrial chambercommunicated with the right-sided ventricle bya valvular orifice with three valves. This ven-tricle showed the crista supraventricularis andthe anterior papillary muscle which are the nor-mal morphological features of the anatomicalright ventricle (Fig. 4b and c). The pulmonaryartery, which had infundibular and valvularstenosis, originated in front of the crista. Theaorta originated behind the crista (Fig. 4c).There were both hypertrophy and dilatation ofthis chamber. There was no left ventricularchamber.



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FI G. 3 Case 2 with laevocardia and ventricular inversion without transposition of the greatvessels. (a) Chest film: this is a clear case of laevocardia, i.e. left-sided apex in the presence of asitus inversus. Notice in this case, also, the prominence of the ascending aorta (horizontal arrow)to the right and the prominent 'pulmonary' segment (vertical arrow) to the left. The hilarvascular markings are rather scant. (b) The electrocardiogram shows a negative P wave in lead Iand VL, suggestive of dextrocardia. As in Case I, VR shows a very positive complex which isindicative of right ventricular hypertrophy of a right-sided anatomical right ventricle (unusualposition for a situs inversus, i.e. there is ventricular inversion). Finally, the sequence of theventricular complexes in the praecordial leads is the expected sequence of normally placedventricles in the presence of right ventricular hypertrophy. This arrangement of the ventricles isabnormal for the situs. (c) Diagrammatic representation showing the spatial relation of the greatvessels, the cardiac cavities, the direction of the apex, and the position of the liver. PA, pulmonaryartery; Ao, aorta; LA, anatomical left atrium; RV, anatomical right ventricle; RA, anatomicalright atrium. LV is the site which the left ventricle should have occupied since the specimen hadno left ventricle. (d) External view of the heart, the great vessels, and the liver. PA, narrowpulmonary artery.a b----_ _ __:~~~~~~~~~~~~~~~~~~ i D1D2 D3

** xr S ~~ ~ ~~ ~~~~~~~~VRVL VF

f a \X~~~~~ ~ ~~ ~~~~3RV1 V2 V3

!~~~~~~~~~~~~~~~~~V 1 5 V6__ad_

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b

¾ w '°.t> EFIG.4 Internal aspect of the cardiac**',>;̂Sj$,chambers of Case 2 with laevocardia and

ventricular inversion withouct transpositionof the great vessels. (a) The anatomical

k PA r -iM!I_rghtatrium is on the left; notice the cristaF 5;terminalis (CT), the pectineal muscles

(PM), the sinus portion (SP). An arrow_ . jR, .>points to the connexion of the inferior vena

Ft_Is-v: . s cava (IVC) with this atrium. The-̂.t_̂ atrioventricutlar orifice is atretic. (b) The

atrium placed on the right shows smoothwalls which are characteristic of theanatomical left atrium; it connects with theinflow chamber of the anatomical right

- ventricle. (c) The ventricle placed on theright shows the featuires of an anatomicallyright ventriccle; the crista supraventricularis

(CS- V) in front of which the pulmonary artery (PA) originates with infundibular stenosis; behindthe crista is a probe placed within the orifice of the aorta (Ao); the itnterventrictular septum istrabecuzlated.

Diagnosis Situs inversus, laevocardia, atresia ofthe left atrioventricular orifice (tricuspid);ventricular inversion without transposition ofthe great vessels; orificial and infundibularstenosis of the hypoplastic pulmonary artery;atrial septal defect.

DiscussionAnatomical outline The following ana-tomical outline seems justified in view of theneed for classification of our cases and becausethere is considerable confusion concerningthe anatomical concepts on visceral situs, onthe position of the cardiac chambers, and ofthe vascular pedicle with respect to thesitus. This confusion is readily apparent inthe numerous names that are used in thenomenclature, most of which are erroneous

(Anselmi et al., I963; Van Praagh and VanPraagh, I967; Stanger et al., I968). We willnot analyse the anatomical concepts fromthe embryological standpoint as they havealready been reported (de la Cruz and daRocha, I956; de la Cruz et al., I959, I967).A visceral situs is the spatial position of

the viscera in relation to a system of sym-metry, which in the case of the cordates isthe bilateral symmetry system. The situs isestablished ontogenetically and phylogenetic-ally before the heart appears. In the systemof bilateral symmetry there are three typesof situs: the solitus, the inversus, and hetero-taxia.The position of the atria is fixed for the

specific situs; therefore there is never 'atrialinversion'; on the contrary, it is the position



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of the ventricles which may vary for aspecific situs, and a malformation character-ized by the disagreement between the ven-tricles and the viscero-atrial situs is desig-nated with the name ventricular inversion(de la Cruz et al., I967) (Fig. 5 and 6).There are two types of ventricular inver-

sion: one in situs solitus and one in situsinversus and both are accompanied alwaysby inversion of the vascular pedicle, whateverthe trunce-conal morphology may be (Fig.5 C, G, H, I, and Fig. 6 C, G, H, I). Thename inversion of the vascular pedicle is usedfor the mirror-image of any of the differenttrunco-conal morphologies of a specific situswithout ventricular inversion (compare G,H, and I with D, E, and F in Fig. 5 and 6).There are three fundamental trunco-conal

morphologies for any situs whether they areassociated with ventricular inversion or not(Fig. 5 and 6). (i) Without transposition ofthe great arteries. The pulmonary arterycrosses in front of the aorta and consequentlyit arises from the anatomical right ventricle.The direction of the pulmonary artery indi-cates the position of the anatomically rightventricle. If this artery is directed from rightto left, the anatomically right ventricle isplaced on the right (Fig. 5D and 6B), and ifthe pulmonary artery is directed from left toright, the anatomically right ventricle isplaced on the left (Fig. 5G and 6D). (2)With transposition of the great arteries. Theaorta is anterior and parallel with respect tothe pulmonary artery, and consequently itarises from the anatomically right ventricle,while the pulmonary artery arises from theanatomically left ventricle. The position ofthe transposed aorta with respect to thepulmonary artery indicates the location ofthe anatomically right ventricle. If the trans-posed aorta is on the right side of the pul-monary artery, the anatomically right ven-tricle is on the right (Fig. 5E and 6H), andif the transposed aorta is on the left side ofthe pulmonary artery, the anatomically rightventricle is on the left (Fig. sH and 6E).(3) With persistence of the common truncusarteriosus. A single artery arises from theheart, and its direction points to the positionof the anatomically right ventricle. If it isdirected from right to left, the anatomicalright ventricle is placed on the right side(Fig. sF and 6I), and if it is directed fromleft to right, the anatomically right ventricleis on the left side (Fig. sI and 6F).

Situs solitusThis is the normal spatial position of the-viscera within a symmetry system in which

FIG. 5 Diagrams representing the relation ofthe atria with the ventricles and, also, the rela-tion of the great vessels with each other and ofthese vessels with the cardiac chambers in situssolitus. RA, anatomically right atrium; LA,anatomically left atrium; IVC, inferior venacava; RV, anatomically right ventricle; LV,anatomically left ventricle; Ao, aorta; PA,pulmonary artery; CT, common trunh.

the anatomically right structures are placedon the right and the anatomically left struc-tures are placed on the left (Fig. 5A).The normal heart of situs solitus is charac-

terized by an anatomically right atrium andventricle on the right side and an anatomicallyleft atrium and ventricle on the left side. Inother words, there is an atrioventricularconcordance. The normal relation of thegreat vessels will then be such that the pul-monary artery is anterior and crosses theaorta from right to left and from the frontto the back (Fig. sD).The three trunco-conal morphologies for the

heart in situs solitus without ventricular in-version are: (i) Without transposition of thegreat vessels. The pulmonary artery crossesthe aorta in front, and from right to left;therefore it arises from the anatomicallyright ventricle placed on the right. This



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morphology is the normal one for a normalheart in situs solitus (Fig. 5D). (2) Withtransposition of the great vessels. The aorta isanterior, parallel to, and placed on the rightof the pulmonary artery; therefore it arisesfrom the anatomically right ventricle placedon the right (Fig. 5E). (3) With persistenceof the common truncus arteriosus. This vessel isdirected from right to left and indicates theright-sided position of the anatomically rightventricle (Fig. sF).

In situs solitus, ventricular inversion ischaracterized because the anatomically leftventricle is on the right and it receives bloodfrom the anatomically right atrium placedon the right (venous atrium), and the ana-tomically right ventricle is placed on the left,and it receives blood from the anatomicallyleft atrium placed on the left (arterial atrium)(Fig. 5C).The three trunco-conal morphologies for the

heart in situs solitus with ventricular inversionare as follows: (i) Without transposition ofthe great vessels, in which the pulmonaryartery crosses in front of the aorta from leftto right and from the front to the back;therefore it arises from the anatomicallyright ventricle placed on the left (Fig. 5G)and it constitutes the mirror-image of thevascular pedicle of a normal heart in situssolitus (inversion of the vascular pedicle)(compare G with D in Fig. 5). This cardi-opathy functions as a transposition of the greatvessels without actually being one anatomic-ally, because the great vessels are not relatedto each other nor with the ventricles as in atrue transposition of the great vessels (com-pare G with E in Fig. 5). Therefore, thedesignation 'clinical transposition' (Stangeret al., I968) for this cardiopathy is erroneousbecause it is not a transposition of the greatvessels and because it ignores the basic mal-formation which is a ventricular inversion. Forthis reason it is best to designate it as ventri-cular inversion without transposition of thegreat vessels (de la Cruz et al., I967). (2)With transposition of the great vessels, theaorta is anterior, parallel, and placed to theleft of the pulmonary artery; therefore itarises from the anatomically right ventricleplaced on the left (Fig. 5H). This malforma-tion behaves from a haemodynamic stand-point as a normal heart, and for this reasonit is currently designated as 'corrected trans-position of the great vessels' (Walmsley,I93I; Abbott, I936; Liebow and McFarland,194I; de la Cruz et al., i959, I962; VanPraagh et al., I964). This designation againis erroneous, since there is no anatomicalcorrection, because the great vessels are

FIG. 6 Diagrams representing the relation ofthe atria with the ventricles and, also, therelation of the great vessels with each otherand of these vessels with the cardiac chambers,in situs inversus. RA, anatomically rightatrium; LA, anatomically left atrium; IVC,inferior vena cava; RV, anatomically rightventricle; LV, anatomically left ventricle;Ao, aorta; PA, pulmonary artery; CT, com-mon trunk.

related with each other and with their respec-tive ventricles in the fashion of transpositionof the great vessels, and because this designa-tion ignores the fact that ventricular inver-sion is the basic malformation in this cardi-opathy (compare H with E in Fig. 5). (3)With persistence of the common truncus arterio-sus. This artery is directed from left to rightand it indicates the left position of the ana-tomically right ventricle (Fig. sI).

In situs solitus, there are two positions ofthe apex: in one, it is directed to the left andthe heart is normally placed, and in the otherone the apex is directed to the right, i.e.constituting a case of dextroversion or dextro-rotation.

Situs inversusThis is the designation used for the spatial



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disposition of the viscera in which the ana-tomically right structures are placed on theleft and the anatomically left structures areplaced on the right, thus constituting themirror-image of situs solitus (Fig. 6A).The normal heart of situs inversus (mirror-

image dextrocardia) is characterized by thefact that the anatomically right atrium andventricle are on the left and the anatomicallyleft atrium and ventricle are on the right.There is also, therefore, an atrioventricularconcordance. The normal relation of thegreat vessels is such that the pulmonaryartery is anterior and it crosses in front ofthe aorta from left to right and from thefront to the back (Fig. 6D).The three trunco-conal morphologies for the

heart in situs inversus without ventricularinversion are: (I) Without transposition of thegreat vessels in which the pulmonary arterycrosses the aorta in front and from left toright, therefore arising from the anatomicallyright ventricle placed on the left. This mor-phology corresponds to the normal heartin situs inversus (mirror-image dextrocardia)and the great vessels are not inverted for thistype of situs (Fig. 6D). (2) With transpositionof the great vessels in which the aorta isanterior, parallel, and placed to the left ofthe pulmonary artery; therefore it arises fromthe anatomically right ventricle placed onthe left (Fig. 6E). (3) With persistence of thetruncus arteriosus. This artery is directedfrom left to right and it indicates the left-sided position of the anatomically right ven-tricle (Fig. 6F).

In situs inversus, ventricular inversion ischaracterized by the fact that the anatomic-ally right ventricle is placed on the right andit receives blood from the anatomically leftatrium placed on the right (arterial atrium),and the anatomically left ventricle is placedon the left and it receives blood from theanatomically right atrium placed on the left(venous atrium) (Fig. 6C).The atria agree with the situs since they

maintain the position that they have inmirror-image dextrocardia, i.e. the normalheart for situs inversus (compare C with Din Fig. 6), whereas the ventricles are invertedbecause they have a completely abnormalposition for a mirror-image dextrocardia(compare C with D in Fig. 6), in spite ofthe fact that they have the same position asa normal heart for situs solitus (compareC in Fig. 6 with D in Fig. 5).The three trunco-conal morphologies for the

heart in situs inversus with ventricular inver-sion are: (i) Without transposition of the greatarteries, in which the pulmonary artery

crosses in front of the aorta, from right toleft and from the front to the back; thereforeit arises from the anatomically right ventricleplaced on the right (Fig. 6G). These arteriesare inverted for a mirror-image dextrocardia(compare G with D in Fig. 6), despite thefact that they have the relation of the vascularpedicle of a normal heart in situs solitus(compare G in Fig. 6 with D in Fig. 5).This cardiopathy functions as a transpositionof the great vessels, even though it is not onefrom the anatomical standpoint. Thereforethe designation 'clinical transposition' (Stan-ger et al., I968) is also erroneous because itis not a transposition of the great arteries andbecause it ignores the basic malformationwhich again is ventricular inversion (compareG with E in Fig. 6). For this reason we call itventricular inversion without transpositionof the great arteries in situs inversus (de laCruz et al., I967). (2) With transposition ofthe great arteries, the aorta is anterior, parallel,and placed on the right side of the pulmonaryartery; therefore it arises from the anatomic-ally right ventricle placed on the right (Fig.6H). This malformation behaves haemodyna-mically as a normal heart and it is currentlydesignated as 'corrected transposition of thegreat arteries' (Walmsley, 1931; Abbott,I936; Liebow and McFarland, I94I; de laCruz et al., I959, I962; Van Praagh et al.,I964). This designation is also erroneoussince the anatomical image is that of trans-position of the great arteries with ventricularinversion. (3) With persistence of the commontruncus arteriosus. This artery is directedfrom right to left and it indicates the right-sided position of the anatomically rightventricle (Fig. 6I). In situs inversus thereare also two positions of the apex: it is eitheron the right, in which case there is a mirror-image dextrocardia, or the apex is directedto the left in which case it is a laevocardia.The cases under discussion are examples

of ventricular inversion without transpositionof the great arteries in situs inversus (Fig.6G), one ofthem with a mirror-image dextro-cardia and the other with a laevocardia.These cases should not be called completeclinical transposition in situs inversus, be-cause the relation of the great vessels betweenthemselves and with respect to the ventriclesdoes not correspond to the anatomical pic-ture of transposition and because it wouldignore the fact that the basic malformationis ventricular inversion. Other authors (Stan-ger et al., I968) would perhaps maintain thatthe position of the ventricles and the relationof the vascular pedicle of our cases are normalfor situs inversus with ventricular inversion.



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We differ from this view because the normalposition of the ventricles and the normalrelation of the vascular pedicle for a situsinversus is that seen in mirror-image dextro-cardia (normal heart in situs inversus) (com-pare G with D in Fig. 6).

In both of our cases there is unequal par-tition of the truncus conus at the expenseof the pulmonary artery associated withdextroposition of the aorta (lateroposition)(de la Cruz and da Rocha, I956). The casewith laevocardia also shows atresia of theleft atrioventricular orifice, which is respon-sible for the absence of the anatomicallyleft ventricle.

Clinical analysis This malformation isextremely rare; perhaps no more than fourcases have been reported to date (Lev andRowlatt, I96I; Van Praagh and Van Praagh,I966; Martinez Pico and Mufnoz, I967) insitus solitus. To our knowledge these twocases with situs inversus may be the first tobe reported in which there is 'isolated ventri-cular inversion' (Van Praagh and VanPraagh, I966), i.e. absence of transpositionof the great arteries.

In the case with mirror-image dextrocardiathe diagnosis of tetralogy of Fallot was madeon the basis of a severely cyanotic and in-capacitating malformation, mainly from thecatheterization findings (see below). Indeedthe radiological picture did not suggest thediagnosis.

In the case with laevocardia the diagnosisof 'corrected transposition of the great ves-sels' was postulated initially on the basis ofour experience and that of others (Lev andRowlatt, I96I), according to which laevo-cardia is frequently associated with trans-position of the great arteries and ventricularinversion. The diagnosis of septal defectsand pulmonary stenosis was also postulatedin this case, but unfortunately no specializedstudies could be made due to the severityof the patient's condition. Though thispatient's heart had no left ventricle it isapparent that the left AV valve was atreticwhile the right one was the tricuspid (threeleaflets). Furthermore, the single ventriclewas unquestionably anatomically right.

In both instances there were two commonphysiopathological features: (i) a venous-arterial shunt across the septal defects;(ii) a decreased pulmonary flow.The analysis of Fig. 7A, a, B, b, shows that

the course of the blood in these malforma-tions, independently of the septal defects,of the intrinsic anatomy of the great arteries,and of the situs, is as abnormal in ventri-

FIG. 7 A, and a, are diagrams representingthe arrangement of the circulatory pattern incases of ventricular inversion with normallyarranged great vessels reproducing the haemo-dynamic pattern of ordinary complete trans-position of the great vessels (diagrams B,and b).

cular inversion with normal relation ofthe great arteries (without transposition ofthe great arteries) (Fig. 7A and a) as inordinary complete transposition of the greatarteries (Fig. 7B and b), thus rendering thehaemodynamic picture in both conditionssomewhat similar. In other words, in themalformation under discussion, blood thathas been oxygenated in the lungs returns tothe anatomically left atrium and enters theanatomically right ventricle from which it isredirected to the lung by way of the pul-monary artery. In the opposite circuit, theblood from the left ventricle enters the aortaand returns to the anatomically right atriumthrough the vena cava without having comein contact with the lungs. This haemodynamicarrangement has been described as 'physio-logic transposition of the circulation withnormal aortopulmonary relationship' (Mar-tinez Pico and Munioz, I967).



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302 Espino-Vela, de la Cruz, Munioz-Castellanos, Plaza, and Attie

Radiology In Case i the prominent seg-ment on the left cardiac border which weknow from the specimen to be, in part, thepulmonary segment, is unusual for a casewith clear lung fields and pulmonary stenosis(see Fig. Ia). This prominent segment wasformed by the combination of the pulmonaryartery and a large anatomically right atrialappendage placed on the left side (see alsoFig. 6G).The case with situs inversus and laevo-

cardia (Case 2) had a cardiac contour whichsuggested initially the diagnosis of trans-position of the great vessels associated withventricular inversion (Fig. 3a). The promi-nent segment pointed by the vertical arrowin this figure was erroneously taken to be theorigin of the aorta, emerging from the leftborder of the heart. This prominent seg-ment was also formed by the combination ofthe pulmonary artery, and the anatomicallyright atrial appendage placed on the leftside.These two structures coincided in the space

existing between the left border of the aortaand the left border of the heart formed bythe anatomically left ventricle (see Fig. ic,3c, and 6G).This prominent segment on the left cardiac

profile has been a useful diagnostic element inventricular inversion with transposition ofthe great vessels in situs solitus where itcorresponds to the initial portion of theascending aorta. This was not the case inthese patients.Another feature of this cardiac contour

was the prominent ascending aorta to theright (Fig. Ia and 3a). This seems to be dueto the dextroposition of the aorta and alsoto the right-sided aortic arch which bothcases had.

Electrocardiography In both cases thediagnosis of situs inversus was substantiatedby the presence of a negative P wave in leadsI and VL. VL had the aspect of a normalVR and vice versa, as far as the P wave wasconcerned (Fig. ib and 3b). In contrastwith this, the morphology of the ventricularcomplexes in the praecordial leads VI toV6 had a sequence which suggested that theactivation of the heart was the mirror-imageof normal for a situs inversus, and suggestiveof ventricular inversion with right ventri-cular enlargement; thence the Rs type com-plexes in Vi and rS type complexes in V6.Such morphologies seem to be compatiblewith extreme clockwise rotation of the ven-tricular septum. The specimens show thatthe anatomically right ventricle is the over-

loaded one. Furthermore, in the case of laevo-cardia, there was no left ventricle. For thisreason a tentative diagnosis in this case hadbeen tricuspid atresia in situs inversus.

Specialized studies From the catheter-ization data of our first case it appears thatthe left-sided (anatomically left) ventriclecould not be entered. The reason for thiswas that there was a stenotic left atrioven-tricular valve. However, the aorta originatedpartly from this ventricle, overriding theseptum, and it was entered with the catheterfrom the opposite ventricle. A very low wedgepressure in a pulmonary vein (7 7 mm. Hg)was indicative of a low pulmonary arterypressure and, by inference, of pulmonarystenosis.

Injection of radiopaque material from theright-sided and anatomically right ventricleinto the overriding aorta simultaneouslyopacified the pulmonary artery. As seen inFig. id, the arrangement of the great vesselsis not in a parallel fashion. On the contrary,the aorta is a posterior vessel and the narrowpulmonary artery crosses it anteriorly. Thesedata were found compatible with a tetralogyof Fallot.Though a higher arterial oxygen saturation

was found in the anatomically left atrium(right-sided), than in the anatomically rightatrium (left-sided), the specimen showedthat the four pulmonary veins entered thelatter chamber. The only explanation forthis (aside from the fact that considerablecomplexity of a case with situs inversus ren-ders catheterization difficult) is a preferentialflow of blood from the pulmonary veins intothe opposite atrium across a large atrialseptal defect.

In the presence of pulmonary ischaemia,a surgical anastomosis between a systemicvessel and the pulmonary artery seemed justi-fied in both patients, inasmuch as patientswith this malformation, as in many with pul-monary stenosis, benefit from an increase offlow to the lungs. In one patient (the oneerroneously thought to be a tetralogy ofFallot) the anastomosis was performed andwas apparently successful; unexpected deathfrom an unidentified cause was probablynot due to the new haemodynamic patterncreated by the procedure.

ReferencesAbbott, M. E. (1936). Atlas of Congenital Cardiac Dis-

ease. American Heart Association, New York.Anselmi, G., Munoz, S., Machado, I., Blanco, P.,

and Espino-Vela, J. (i963). Complex cardiovas-cular malformations associated with the correctedtype of transposition of the great vessels. AmericanHeart_Journal, 66, 614.



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de la Cruz, M. V., Anselmi, G., Cisneros, F., Rein-hold, M., Portillo, B., and Espino-Vela, J. (i959).An embryological explanation for the correctedtransposition of the great vessels: additional des-cription of the main anatomic features of thismalformation and its varieties. American HeartJournal, 57, 104.

-, and da Rocha, J. P. (I956). An ontogenetictheory for the explanation of congenital malforma-tions involving the truncus and conus. AmericanHeart_Journal, 51, 782.

-, Espino-Vela, J., Attie, F., and Munioz-Castel-lanos, L. (1967). An embryologic theory for ven-tricular inversions and their classification. AmericanHeart_Journal, 73, 777.

-, Polansky, B. J., and Navarro-L6pez, F. (I962).The diagnosis of corrected transposition of thegreat vessels. British HeartJournal, 24, 483.

Lev, M., and Rowlatt, U. F. (I96I). The pathologicanatomy of mixed levocardia. A review of I3 casesof atrial or ventricular inversion with or withoutcorrected transposition. American Journal ofCardiology, 8, 2I6.

Liebow, A. A., and McFarland, W. (I94I). 'Correctedtransposition' and persistent rudimentary 'right

aorta' as evidence in support of Spitzer's theory.Archives of Pathology, 32, 356.

Martinez-Pic6, A., and Muiioz, A. (I967). Inversi6nventricular; transposici6n fisiol6gica de la circula-ci6n y relaci6n aorto-pulmonar normal. BoletinAsociacion Medica de Puerto Rico, 59, 26.

Stanger, P., Benassi, R. C., Korns, M. E., Jue, K. L.,and Edwards, J. E. (I968). Diagrammatic portrayalof variations in cardiac structure. Reference totransposition, dextrocardia and the concept offour normal hearts. Circulation, 37, Suppl. IV.

Van Praagh, R., and Van Praagh, S. (I966). Isolatedventricular inversion. A consideration of themorphogenesis, definition and diagnosis of non-transposed great arteries. American Journal ofCardiology, 17, 395.

- , and - (I967). Anatomically corrected trans-position of the great arteries. British Heart_Journal,29, I I2.

- , - , Vlad, P., and Keith, J. D. (I964). Ana-tomic types of congenital dextrocardia. Diagnosticand embryologic implications. American Journalof Cardiology, 13, 510.

Walmsley, T. (I93I). Transposition of the ventriclesand the arterial stems. J'ournal of Anatomy, 65,528.



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