Br Heart J: first published as 10.1136/hrt.36.8.747 on 1 August 1974. Downloaded from British Heart_Journal, I974, 36, 747-759. Double inlet left ventricle Straddling tricuspid valve' Rajendra Tandon,2 Anton E. Becker, James H. Moller, and Jesse E. Edwards From the Department of Pathology, United Hospitals - Miller Division, St. Paul, Minnesota; the Depart- ments of Pathology and Pediatrics, University of Minnesota, Minneapolis, Minnesota; and the Department of Pathology, University of Amsterdam, The Netherlands Eleven cases of double inlet left ventricle have been presented. Double inlet left ventricle is characterized by the tricuspid valve opening partly (partial type) or completely (complete type) into the morphological left ventricle. The morphological right ventricle is usually hypoplastic but may be normallyformed. Even when the right ventricle is hypoplastic, both the sinus and the outflow portions of the right ventricle are recognizable. Double inlet left ventricle has been classified into two groups according to whether the ventricles are nor- mallyplaced (noninverted; concordant with the atria) or inverted (discordant with the atria.) This classification indicates the anatomicalrelation of the atrioventricular valves and the ventricles. When the ventricles are non- inverted, a right-to-left shunt resultsfrom the communication of the right atrium with the left ventricle. On the other hand, with inverted ventricles a left-to-right shunt resultsfrom the left atrium communicating with the inverted left ventricle. Further details in circulation depend upon the great vessel-ventricular relations. Clinically, the patients presented with cyanosis when pulmonary stenosis was present and with congestive cardiacfailure when pulmonary stenosis was absent. http://heart.bmj.com/ The electrocardiogram is helpful in suggesting the presence of inverted or noninverted ventricles. Right and left atriograms are essential for the diagnosis of straddling tricuspid valve in noninverted and in inverted ventricles, respectively. Straddling tricuspid valve is an anomaly wherein appropriate to add to the published reports a the tricuspid valve overrides the ventricular septum description of additional cases so as to provide addi- and communicates with both ventricles. This con- tional material for a more comprehensive under- on September 28, 2021 by guest. Protected copyright. dition may be considered as one form of double standing of double inlet left ventricle. inlet left ventricle. In another form of the latter Eleven cases with double inlet left ventricle condition the tricuspid valve opens entirely into formed the basis for this study. Necropsy had been the left ventricle, as does the mitral valve. The sub- done in all, and IO specimens were available for ject of double inlet left ventricle and straddling re-evaluation. Clinical and radiological findings were tricuspid valve have received major attention only available in all, and the electrocardiograms in IO in recent years. The subject is somewhat complex cases. in that variations in the positions of the ventricles and of the great arteries may be associated and Definition of terms mitral atresia may be present. Because of the foregoing and the fact that a lim- Inversion ited number of cases have been reported, it appears The term inversion indicates a mirror image of the usual with regard to right and left orientation. Received 27 February 1974 Anteroposterior relations are not altered. Inversion 1 This study was supported by a U.S. Public Health Service involve the entire as in total situs in- Research Grant and a Research Training Grant from the may body, National Heart and Lung Institute. versus, or it may affect only portions of the cardio- 2 On leave of absence from the Departnent of Cardiology, All vascular system. Inversion may be confined to the India Institute of Medical Sciences, New Delhi, India. ventricles, including atrioventricular valves ('isol- Br Heart J: first published as 10.1136/hrt.36.8.747 on 1 August 1974. Downloaded from 748 Tandon, Becker, Moller, and Edwards ated ventricular inversion') or great vessels, while the atria and other organs are normally positioned. Thus, ventricular inversion implies that the mor- phological right ventricle is left-sided and the mor- phological left ventricle, right-sided. The term non- inverted applies to normal or usual relations. The atrioventricular valves may be considered part of the inflow portion of the ventricles so that the natural valve for the left ventricle is the mitral and for the right ventricle the tricuspid. If the ventricles are inverted, so are the atrioventricular valves. This means that with isolated ventricular inversion the anatomical tricuspid valve lies between the left atrium and the anatomical right ventricle, while the mitral valve lies between the right atrium and the right-sided anatomical left ventricle. Transposition of great vessels Transposition of the great vessels is defined as an abnormal external relation of the great vessels in that the aorta occupies a position more anterior than normal and the great vessels lie parallel to each other. The aorta arises from the morphological right ventricle and the pulmonary trunk from the mor- phological left ventricle. In addition to transposi- tion, the great vessels may show inversion or non- inversion. If the transposed aortic valve lies to the right of the pulmonary valve, there is noninversion or http://heart.bmj.com/ d-transposition. If the transposed aortic valve FIG. lies to the left of the pulmonary valve and the as- I Case 3. Interior of the noninverted left cending aorta sweeps along the left side of the pul- ventricle (L.V.). The mitral valve (M.) and part of monary trunk, there is inverted or the tricuspid valve (between arrows) communicate 1-transposition. with this chamber. The aorta (A.) arises from the left ventricle. Double inlet left ventricle Double inlet left ventricle may be designated as into the morphological left ventricle which may be on September 28, 2021 by guest. Protected copyright. either of the partial type or of the complete type. inverted or non-inverted. This is to be distinguished The partial form of double inlet left ventricle in- from the more common state of common ventricle. volves either non-inverted or inverted ventricles In the latter, the sinus portion of the right ventricle and is characterized by the tricuspid valve over- is not formed, while in those cases called double riding (straddling) a ventricular septal defect and inlet left ventricle there is an identifiable right opening partly into the morphological left ventricle ventricular sinus. and partly into the morphological right ventricle (Fig. i and 2). The mitral valve may either be atretic or present. If present, the mitral valve opens Anatomical types entirely into the morphological left ventricle. The Each of the i i cases of double inlet left ventricle to morphological right ventricle may be hypoplastic be described showed certain features in common. or well formed. However, the inflow (sinus) and These were situs solitus and normal pulmonary the outflow portions of the right ventricle are both venous and systemic venous connexions, as well as recognizable. Excluded from the definition of absence of any splenic anomaly. double inlet left ventricle are cases of common In IO of the i i cases the partial type of double atrioventricular valve. inlet left ventricle was present and in one, the com- The complete form of double inlet left ventricle plete type. In the following anatomical classification, is that wherein the tricuspid valve opens entirely primary subdivision will be on the basis of the pre- Br Heart J: first published as 10.1136/hrt.36.8.747 on 1 August 1974. Downloaded from Double inlet left ventricle 749 FIG. 2 Case 6. a) Interior of the right atrium (R.A.) and inverted morphological left ventricle http://heart.bmj.com/ (L.V.). The fossa ovalis (F.O.) identifies the right atrium (R.A.). The inverted mitral valve (M.) lies between the right atrium and the morphological left ventricle. The inverted tricuspid valve (T.) straddles the ventricular septum and communicates, in part, with the morphological left ventricle. b) The left atrium (L.A.) and the inflow portion of the inverted morphological right ventricle (R. V.). The tricuspid valve also communicates in part with the inverted right ven- tricle. sence or absence of ventricular inversion and of the septal and either the posterior or the anterior on September 28, 2021 by guest. Protected copyright. transposition of the great vessels. leaflets of the tricuspid valve were the straddling ones. Chordae from these leaflets attached to the left ventricular side of the ventricular septum or to Double inlet noninverted left ventricle papillary muscles of the left ventricle. The right (group I) ventricle was hypoplastic in 'each case (Fig. 3a) There were 5 specimens wherein the ventricles except the one (Case 2) in which aortic atresia was were non-inverted and were concordant with the also present (Fig. 3b). In this case the right ventricle atria. In each, the aouble inlet left ventricle was of was larger than the left ventricle. the partial type. In 3 of these, the great vessels were The 5 cases with non-inverted (concordant) normally related and in 2 the great vessels ex- ventricles could be subdivided into two groups hibited d-transposition. according to the position and origin of the great The mitral valve was atretic in one (Case 4) and vessels. In 3 cases (Cases I to 3) the great vessels present in each of the remaining 4 cases. When were normally interrelated and arose normally present, the mitral valve opened entirely into the (Fig. 3). (In Case 2, aortic atresia was present.) In left ventricle. Through a ventricular septal defect, the other 2 cases, the great vessels exhibited d- the tricuspid valve straddled the ventricular septum, transposition and the aorta arose from the right opening partly into the right and partly into the left ventricle, while the pulmonary trunk arose from the ventricle (Fig.