334

Cor Triatriatum Dexter: Two-DimensionalEchocardiographic Diagnosis

ERNERIO T. ALBOLIRAS, MD, WILLIAM D. EDWARDS, MD, FACC,

DAVID J. DRISCOLL, MD, FACC, JAMES B. SEWARD, MD, FACC

Rochester, Minnesota

lACC Vol. 9. No.2Febroary 19X7:334-7

Cor triatriatum dexter is a malformation resulting fromlack of normal regression of the embryonic right valveof the sinus venosus. In this situation, the right atriumis divided by a membrane into two chambers. Two-di­mensional echocardiography was used in the antemor-

Cor triatriatum dexter is a very rare cardiac anomaly inwhich a membrane divides the right atrium into two cham­bers (I). Antemortem diagnosis of this and other variationsof pathologic persistence of the embryonic right valve ofthe sinus venosus can be difficult. Real-time two-dimen­sional echocardiography allows for an accurate identificationof such malformations in the right atrium. We describe aneonate who had complex congenital heart disease and as­sociated cor triatriatum dexter diagnosed antemortem bytwo-dimensional echocardiography and confirmed at au­

topsy.

Case ReportA 2.61 kg white girl was born to a 30 year old mother

who had a bicornuate uterus and three previous spontaneousabortions. Because of spontaneous membrane rupture andfetal bradycardia. the baby was delivered at 37 weeks' ges­tation by cesarean section.

Apgar scores were 7 at I minute and 5 minutes. Heartrate during sleep was 55 beats/min. There was a grade 2/6systolic ejection murmur at the left sternal border. Therewas no diastolic murmur. The liver was not enlarged. Theelectrocardiographic findings were consistent with congen­ital heart block.

From the Section of Pediatric Cardiology. the Section of Medical Pa­thology and the Division ofCardiovascular Diseases and Internal Medicine.Mayo Clinic and Mayo Foundation. Rochester. Minnesota.

Manuscript received May 12. 1986; revised manuscript received July29. 1986; accepted September 2. 1986.

Address for reprints: James B. Seward. MD. Mayo Clinic. 200 FirstStreet SW. Rochester. Minnesota 55905.

iD19X7 by the American Collegeof Cardiology

tem diagnosis of this rare cardiac anomaly in a neonate.Associated cardiac lesions were also documented. Thepatient died, and findings were verified at autopsy.

u Am Coli CardioI1987;9:334-7)

Two-dimensional echocardiogram. There was situs so­litus of the atria and viscera, with atrioventricular and ven­triculoarterial concordance. A large membrane within theright atrium divided the atrial cavity into two chambers (Fig.I). The membrane extended from an inferior attachment justabove the tricuspid anulus, at the level of the rim of theinferior vena cava orifice, to a superior attachment at theroof of the right atrium, along the crista terminalis and thelateral rim of the superior vena cava. The inferior portionof the membrane was shaped like a wind sock, with itsconvexity toward the tricuspid orifice.

During ventricular systole (Fig. fA), the portion of theright atrium medial to the membrane appeared to be dis­tended, probably secondary to the returning systemic venousblood. During ventricular diastole (Fig. IB), the superiorportion of the membrane was pulled toward the atrial sep­tum. This pulling was probably due to the shunting of theaccumulated blood across the foramen ovale during the car­diac cycle. Also, during diastole, the inferior wind sockportion of the membrane was carried toward the orifice ofthe tricuspid valve and the right ventricle.

Injection of contrast solution (0.5 ml of saline solution)into the inferior vena cava through an umbilical venouscatheter showed opacification of that portion of the rightatrium medial to the membrane. The entire contrast flowpattern was from the right atrium to the left atrium throughapatent foramen ovale. Subsequent flow was coursed to theleft ventricle, with eventual opacification of the right ven­tricle through a ventricular septal defect.

Additional echocardiographic findings included an 8 mmmembranous ventricular septal defect with an aneurysm ofthe membranous septal remnant. The myocardium appearedto be hyperrefractile and thickened and had a "spongy,"

0735·1097/X7/H50

JACe Vol. ~. No. 2February IlJg7:334- 7

ALHOU RAS ET ALCOR TRIATRIATU M DEXTER

335

highly trabeculated appearance and decreased contractility.The pulmonary valve was thickened , domed during systoleand had a greatly reduced orifice. There was a patent butnan-ow ductus arteriosus.

Hospital course. Cardiac catheterization was performedwhen the infant was 2 days old and findings were similarto those of echocardiograph y. Total tricuspid obstruction bythe right atrial membrane could not be documented. Thecatheter could be advanced easily from the right atrium tothe right ventricle. The left ventricular end-diastolic pressurewas 23 mm Hg, the end-diastolic volume was 224% ofnormal and the ejection fraction was 46%. The peak systolicgradient across the pulmonary valve was 12 mm Hg. Theinfant developed severe metabolic acidosis toward the end

Figure l. A, Subcostal four chamber view during systole. Theecho-dense membrane (bordered by arrowheads) is apparent withinthe right atrium (RA). septating the atrium into two chambers.The inferior portion of the membrane is shaped like a wind sockwith its convexity facing the tricuspid orifi ce. The right atrialportion medial to the membrane isdistended withsystemic venousblood entering the atrium. B, Subcostal four chamber view duringdiastole. The systemic venous blood accumulated medial to themembrane (bordered by arrowheads) has been shunted across thepatent foramen ovale, pull ing the more superior portion of themembrane toward the atrial septum. At the same time. the inferiorwind-sock-like portion is carried toward the right ventricle. Themost superior portion of the septating membrane is evident in thisview. Co Parasternal short-axis view. The wind-sock-like portionof the septatingmembrane (bounded byarrowheads) inthemedialpart of the right atrium looks circumferential. because it is dis­tended with blood. A = anterior; AV = aorticvalve; I = inferior;L = left; LA = left atrium; LV = left ventricle; LVO = leftventricular outflow tract; P = posterior; R = right; RV = rightventricle; RVO = right ventricularoutflow; S = superior; VS =ventricular septum.

of cardiac catheterization . There was progressive deterio­ration despite the use of alkali. inotropic agents and trans­venous cardiac pacing. She died a day later.

Postmortem examination. Congenital heart disease wasassociated with thoracoabdominal situs solitus and a uni­lobed left lung. A large septating membrane was present inthe right atrium. consistent with cor triatriatum dexter (Fig.2). Except for a slitlike perforation along its posterosuperioraspect. the membrane separated the venae cavae and coro­nary sinus from the right atrial appendage and tricuspidorifice. The lower half of the membrane was redundant andwas shaped like a wind sock. with the convexity toward thetricuspid orifice. The foramen ovale was patent, and thetricuspid anular size was normal. There was an 8 mm di-

336 ALBOLIRAS ET AL.COR TRIATRIATUM DEXTER

lACC Vol. 9. No. ~

Februar y 1987:334- 7

Figure2. Postmortem specimen bisected to simulate the subcostalfourchamber view(compare with Fig. IA) . The membrane (whitearrows) divides the right atrial cavity in two. The smooth-walledportion of the right atrium. which receives the venae cavae. ismedial to the membrane. whereas the pectinate muscles. atrialappendage (not seen) and tricuspid valve orifice are lateral. Thelower portion of the membrane is shaped like a wind sock andoverlies the tricuspid valve orifice. Bothventricles have trabecular(spongy) apices. FO = foramen ovale (black arrows); Iveinferior vena cava: other abbreviations as in Figure I .

ameter membranous ventricular septal defect partially ob­structed by the septal tricuspid leatlet and by a small an­eurysm of the anterior tricuspid leaflet. In addition. therewere four I to 2 mm muscular ventricular septal defects ofthe anteroapical trabecular septum. The myocardium had aspongy characteristic with extensive fine intracavitary tra­beculations. There was pulmonary stenosis due to a thick­ened three cusped pulmonary valve without commissuralfusion. The ductus arteriosus was patent but narrow. Anonobstructive shallow supravalvular mitral ridge was alsoobserved.

Discussion

Normal embryogenesis. During early cardiogenesis, theright horn of the sinus venosus is guarded by two valves,the right and the left venous valves (2). The smaller leftvalve becomes incorporated in the septum secundum, butthe right valve almost completely divides the right atriuminto two chambers. This structure normally regresses be­tween the 9th and the 15thweek of gestation, as the cephalicportion forms the crista terminalis and the caudal portiondevelops into the eustachian valve of the inferior vena cavaand the thebesian valve of the coronary sinus. Extensive

fenestrations of the right venous valve may result in a web­like Chiari's network (3).

Persistence of right sinus venosus valve. Lack of nor­mal regression of the right valve of the sinus venosus mayrarely occur. This can result in abnormalities ranging frompartial septation of the right atrium by a prominent eusta­chian valve to complete division of the right atrium (cortriatriatum dexter) (4). In other cases. the right valve of thesinus venosus may form a pendulous wind-sock-like struc­ture (5). Depending on the length of the "stalk" and whereit is carried by blood flow, the wind sock may obstruct thetricuspid orifice (6), right ventricular outflow tract (5), in­ferior vena cava (7) or atrial septal defect (8). Antemortemdiagnosis of this malformation isdifficultand, in mostcases,can be appreciated only by visual inspection at operation orautopsy.

Role of echocardiography. High resolution two-di­mensional echocardiography is a valuable tool in identifyingthe location, size and site of attachment of anomalous rem­nants of the right sinus venosus valve. To our knowledge,very few echocardiographic reports on this malformationexist in the English literature. M-mode echocardiographicfeatures have been described (5.9). Using two-dimensionalechocardiography, Gussenhoven et al. (9) described a pe­dunculated structure extending from the right atrium, justabove the tricuspid valve, into the right ventricle and acrossthe pulmonary valve. In another report (6), a Chiari's net­work coexisted with a wind-sock-like structure that arosenear the inferior vena cava orifice. However, we could notfind any report describing the two-dimensional echocardio­graphic findings of cor triatriatum dexter.

In the presentcase, the diagnosis of cor triatriatum dexteris warranted because of the extensive superoinferior attach­ment of the septating membrane. In this condition, the amountof blood that is shunted across a patent foramen ovale isdetermined by the extent of septation of the right atrium,the presence of fenestrations in the membrane and the me­chanical obstruction of the tricuspid orifi ce by the redundantportion of the septating membrane. An echocardiographiccontrast study enabled us to determine the degree of rightto left shunting of the systemic venous blood across thepatent foramenovale. Although complete right to left shunt­ing occurred at the atrial level, the presence of ventricularseptal defects and a patent ductus arteriosus allowed pul­monary blood flow to be maintained. The fenestration inthe superoposterior aspect of the membrane may have per­mitted passage of the catheter from the right atrium to theright ventricle during cardiac catheterization.

Associated cardiac lesions. There is a high frequencyof serious congenital cardiac malformations associated withpathologic persistence of the right valve of sinus venosus.The most commonlyobserved anomalies include pulmonaryatresia or stenosis, hypoplastic right ventricle and tricuspidvalve atresia or hypoplasia (1,4). A substantial contributing

JACC Vol. 9. No.2February 1987:334-7

ALBOLIRAS ET AL.COR TRIATRIATUM DEXTER

337

factor to the hypoplasia of the right ventricle and pulmonaryarterial trunk has been believed to be the direction of bloodflow into the left atrium and away from the right ventricle(4). The hypoplastic left heart syndrome also has been re­ported (6).

Implications. It is important to look for malformationsin the right atrium, particularly when congenital right heartlesions are present. Two-dimensional echocardiography isa valuable tool for the evaluation of the subdivided rightatrium that, if not identified, could complicate surgical in­tervention for the more serious associated cardiac malfor­mations.

ReferencesI. Hansing CE, Young WP, Rowe GG. Cor triatriatum dexter: persistent

right sinus venosus valve. Am J Cardiol 1972;30:559-64.

2. Yater WM. Variations and anomalies of the venous valves of the rightatrium of the human heart. Arch Pathol 1929:7:4IS-41.

3. Werner JA, Cheitlin MD. Gross BW, Speck SM. lvey TO. Echocar­diographic appearance of the Chiari network:differentiation from right­heart pathology. Circulation 1981 :63:1104-9.

4. Doucette J. Knoblich R. Persistent right valve of the sinus venosus:so-called cor triatriatum dextrum: review of the literature and report ofa case. Arch Pathol 1963:75:105-12.

5. Battle-Diaz J. Stanley P, Kratz C, Fouron J-C. Guerin R. DavignonA. Echocardiographic manifestations of persistence of the right sinusvenosus valve. Am J Cardiol 1979;43:850-3.

6. Weinberg PM, Peyser K, Hackney JR. Fetal hydrops in a newbornwith hypoplastic left heart syndrome: tricuspid valve "stopper." J AmCoil Cardiol 1985:6:1365-9.

7. Rossall RE. Caldwell RA. Obstruction of inferior vena cava by a per­sistent Eustachian valve in a young adult. J Clin Pathol 1957:10:40-5.

8. Jones RN. Niles NR. Spinnaker formation of sinus venosus valve: casereport of a fetal anomaly in a ten-year-old boy. Circulation1965:38:468-73.

9. Gussenhoven WJ. Essed CEo Bos E. Persistent right sinus venosusvalve. Br Heart J 1982;47:183-5.