Mitral Atresia with a Large Left Ventricle and an Underdeveloped Or Absent Right Ventricular Sinus: Clinical Profile, Anatomic Data and Surgical Considerations

JACC Vol . 19, No. 7 1561 June 1992 :1561-76

PEDIATRIC CARDIOLOGY

Mitral Atresia With a Large Left Ventricle and an Underdeveloped or Absent Right Ventricular Sinus: Clinical Profile, Anatomic Data and Surgical Considerations

HIDETO SHINPO, MD, STELLA VAN PRAAGH, MD, IRA PARNESS, MD,

STEPHEN SANDERS, MD, MARIAN MOLTHAN, MD, FACC, ALDO CASTANEDA, MD, PHD, FACC

Boston, Massachusetts

In mitral atresia with a large left ventricle, the tricuspid valve is evidence, or both, of tricuspid regurgitation was present in 14 either straddling and biveutricular or entirely left ventricular . T o cases (56%). learn how to assess the identity of the tricuspid voice in such cases It is concluded that 1) the Identity of the atrioventricular valves 15 heart sv oimms were examined as well as the echocardiograms is reflected in their chordal attachments ante aenurately than in of 10 living patients . When the right ventricular sinus was their leaflet morphology and dey : s;s primarily an the type of underdeveloped (11 cases), a straddling Iekuspid valve was ventricular loop present; 2) as a role, the tlitsrspid valve is present ; when it was absent (14 cases), the tricuspid valve was right-sided in D-looped and tuft-sided to Ldonped ventricles ; entirely left ventricular. 3) valve identity expressed as the number and position of the Regardless of biventricular or exclusively kit ventricular at- papillary muscle attachments is generally recognizable echocar- ta hments, the tricuspid valve was tricommissnral (at postmortem diographically and can be used to diagnose the type of ventricular examloadon or on echocardiography) in 22 cases (88%). Its loop that is present; and 4) the presence and degree of tricusald chordal attachments showed considerable variations but were regurgitation deserve attention when choosing oplimad initiative usually par'aseplal or on the ventricular septa) crest a conal surgery. septum . When biventricular, the tricuspid valve straddled (J Am Col Cordial 1992;19:1561-76) through an Intel ventricular septal defect. Clinical or anatomic

As a rule, atresia of the mitral or tricuspid valve is associated Methods with extreme underdevelopment of the corresponding ven- Study cases and petlents. Among the 3,052 heart speci. tricle. Yet atresia of the mitral valve has been reported (1-7) mens from the Cardiac Registry of the Children's Hospital in to occur with a normal-sized or even a larger than normal left Boston, we identified 15 cases of mitral valve atresia asso- ventricle . In such cases, the single patent atrioventricular ciated with a well developed or enlarged left ventricle and an (AV) valve entering the morphologically left ventricle repre- underdeveloped or absent right ventricular sinus . In addi- sents the tricuspid valve. tion, we compared the morphology of what we considered to What is the underlying morphogenelic process of this be the left ventricular or straddling tricuspid valve in the apparent paradox? How can one differentiate a left ventric- cases from this series with the morphology of the left ular tricuspid valve from a left ventricular mitral valve? Does ventricular mitral valve in 72 postmortem cases of tricuspid a left ventricular tricuspid valve function normally? If it does valve atresia and with the morphology of the AV valves in 55 not function normally, what are the surgical implications and autopsy cases with a double-inlet left ventricle . therapeutic options in patients with this condition? This We also searched our computerized echocardiography study, which includes the largest series of patients with this data base for the diagnosis of AV or ndtral valve atresia rare cardiac malformation to date, attempted to answerthese during the years 1991 to 1990. We then reviewed the records questions. of those patients whose left ventricle was reported as normal or enlarged in size . On the basis of the apparent ventricular looping, as well as the morphology of the patent AV valve, we identified nine patients whose atretic valve was consid- From the Departments of Cardiology, Cardiovascular Surgery and Pathol- ogy, C.iidrcos Hospital, Boston, Massuhusetls. ered to be the mitral valve . All nine patients had a large left Menuw6l t remind July 29, 1991 ; revised maause,ipt received Novem- ventricle and an underdeveloped or absent right ventricular ber 14, 1991, accepted December 5, 1991. sinus; all nine are alive . One additional patient (Case 25, Adtaovrfor rcpdu5 : Stalls Van Praagh, Mn, children's Hospital, 309 Lonawood Avenue, Boston, Massachusetts 02115. Table I) was diagnosed angiocardiographically as having a

01992 by the American College of Cardiology 0735-1997192,55.01)

Table 1. Mitral Atresia With a Large Left Ventricle : Anatomic Data, Surgical Procedures and Clinical Course in 25 Cases

Csse PM No ., ClardseSegments PFO or ASD 06500 Cardlte Agree Opera=, Staideal Pmcedam and N No. Age,'Gendcr and Chambers (rose) Tricuspid Valve VSD (nor,) Grear Aredea Fhtdieg, Clmlml (rare, A. Let -Sided Mint A.-in

I ASS-163, RAE . PFO snaddlingantIf,tMmeunissurel, AVC type and Sm ell PA, N apemtionn,Cyareo d severe dyspne, 2 days, M .all RV attechtS On RVFW, VS real ant CS mat, bP5 omteapan m Medical treatment . D and PMPM TV I(x 2~ Dy C72-107 (S,D,S), RAH+E, PFO, sepe 1° Soadmlng ant If, oicommissurat, AVCC,peobso Natmd Small FDA, coemheoo Noopemtion.Cyarmsisandseveredyspota, D 2.5 mo, M all RV. bulges , RA attaches an RVLW. VS crest TV BC tmnk SVTdurlngcandmcntbetenratioe,livedIn LAH, LVE and PMPM x 5) an Oa tent for 3 ma A73-78, (5,0,5), RAE. Sergtaol A5D Straddling an II, oicottMifsaral, AVC type oboe Mild ca arcs Car Iriabiatunr, eingda 2 mot PAR, (HF de-ad. 6 yr. A511 and 6.51eF em ill RV, (15 x IS) edandanr, attaches on RVSep, by TV LOrtst(um. repeGOfunespectedmrtrientatunr,anemp, LAH. LVE LVSepi. ALPM and PMPM, (19 . 16) inttamural LCA to repair a$ if it Were CAVC. Died 7 b Sy TR poatop. D Lmmg, (s,D,S), RAE, Large argical Entire)y into LV, triwmmlorord, Smell BVF, mid. MPA band FDA, COS mifira 25 mot ASR and PAR . CHF partly con5Olled; 8 yr, F ..la absent RV ASD mi1d7R )stake Isege a reengeede PAD migmtivn, te1Wtog is RPA 550001 a and 0 as, IAE, VSDCTV fbw .LSVC LPAhypcteeerdos.6'.leoroImage, PD.A LYE attathaxnts -etna- .RSVC-.RA OIdedwith etamvtSdnvimLPA0000 Out its loner pee_ foB from 701. 33. Mild TR. 7 yr: run RSVC to RPA anastoetoeis (Gkrm). Doing web 10 dq poelop. Living, (S,D,S), RAE, Lvg orpral EnurelymlaLVlravmmssuml, Small reotriatve Nuance LSVC to CoS, RPV5 8 mo to 17 yr. cyenalr dmrczad sranona, an 291St yr. M absent RV ASD re4erdanl,noTR BVF eorR )with dd~.17 yr. reeunem PAPA , quiteidier A LVH+E 22, LV 9S5Ao - S3%. ASR Lang biopsy = normal pd--y vessels 23 yr: pomp NVA preame - 10. 26 yr. attempted ~'oWlmmemy amslomosis. Imposeibk d perfonR blouse of nYSO«b on of 9PV5 d 28Rx yr. letetmitreot aotal Sseer W-Works.,k- .-as a prvxtr. MaKed, one cbad. b A6a-268, 7GA, (S,D,D), ASDN(6x3 .5) Srtaddlirgantlf,bOannannssurd, AYC bye abso An isthmus LSVC to ImgeBC =GS, No ration . Rapid deterioration dspgt 10 days, M RAE, 55100 RV. thick mdunamt Se, attaches oa by TV (S o 5) hypop os eiwogrsdve manes,. Ded 3 days aner LVH+E CS, VS erect and PMPM PDA cardiac ntheteNZataunt. 7 A71-111, TC2A,(S,D,D), Surgirnl ASD Sbaddlhg ant and eepret bs, AVCtyptand Puanonaey 2011 : ASR,Wete0055ehusLtmprovedfore 23 day, m RAE, Small RV. (73 x 16) tricanasssorel, shed, on posstte for C oleeela Rw days, died 22 days poetop . LAH,LVH RVFW, VS erestand PMPM of LV (9 x 7) 8 A81-50, DORV, (&DiD), sr Wca1 AS Straddling am std repeal bs, AVE type SOW'S SupemirMenar B em: ASR and PAR d imprtmmeoe of CHF 951, yr, M RAE, large, i if Rimmmsraml.ad, rote datee a (29 x 21) acquired v+atrirdes ",yr. modified Foneee proeemne RV ltd, Ifs, a on APM and PPM I rrostsoitidive =IPA diachargod 13 days pmmp, remand m 7 LAH+E RV, VS crest and Pk1PM of days dy_pneie, acitlak, b large pleural LV,TR Rus)orsand died 0 the ER. 9 Lsnng, TGA, (S,D,D). Large -pea! font pwvLS of Large AVC type MPA band LSVC to COS. RAVE 25 sent ASR and PAR . 5 yr. and syaorYs. 7'Vnyr,F RAE, amdtRV, ASD mst; vrodemte to severe "d-sad- mbdydetreaxdc,ceraaelok0Mry LAE, LVH TR superoinfreia SStayr..OASUSSestedaodovetsewn, venlddes LSVCeaeelamancdIOLPA .644,yrsubfo mu5maereeeoosisdpaasutegeadlene7R-a0. krrtyr, sobAO sbaosis remeeon W TV pGwy.Osrtop t5aeedtedd Clubbing persist. cy ..ah PAR' 10 Ltwng, TGA,15,D,D7, Saeeiod ASD Straddling, eeimremioseeral AVC type d ant BOA band 5 w«lestan. bounce acrid septost«ty. 7 mo, M RAE, Small RV, ex omens snows RA o 2, [A= tl . Blede abut -at rA, ledge erpeoeomyrtwdminRA=6,fA=9atd ,. C LVH+E kssedogo[(7IP.7mo:nthstmwsbfPA band gaediest - 70. RA= 7, LA = 12, PA - 25. ASR. Poaop PA - 18. ^o

Table 1 . Conthwed

C C- 17111~1~1 T6 ... p,d V,l- vsv( . .) G-1 A,..k, otlFindings CImICUICuvrx

A. LAIRdvIMiwlAlrctir " TGA., ,, ,V~i 1, 1-fla-. L sL 1,1~W I. IL'S . PDA N. 7%cek.,: 1,11WA auiJl A, RA ml free IsubPO) count mud :nays mwr, wall MPA LSVC 1, C CoS n: 5511 and PAR; rapid do:eriurad,n RAE, uhsc^1 111 a 11 x hl 81',,IAO1 bA R"F, -1 in RA, small PDA poll MPANO -A, AIR -d fur 2 'F - ill, 1 mv.2", n then CW ccvncdr . AI I of .%T t Ginahem IIV' 11 tAL111 P,M'M.Tp, P,d,&1- S . LEE

SLIl,,,.IASf) I-!tydALP, I . 'i, C BYE ,F C Pun, PS -d .bps RUE :d1.s.'nr Ill x Ill RV simw, LAI l, ASR. LA

15 lyAL'-, .L%'~L ."-'' P M-'i,.".l. - ],,1S 1AA A%, PFn ruches nn euEr PV1 . UDA " and 17 x 3, In Living. IN AM Nor- PS .0 bPS 7 1111,LVINE 1 .5 24 , PA=AS .Ny1,ASR,Urumulm

IL Ri1IIISidcd Mind Allan,. Mild cy MR T7, FGA,I&L .Ll .RV . PFD AVCl,2 lypuS HI wmu MPA N1, -ii-I An- and d--6 RAL,11111 27 . dM"1 .V . lfar scvvc

II AWLpl3, PEE r. nnmoo Roan TGA~LA.,EL.~. 1~ . %al.aiV.scail AVC 11 MPA h- S .lbA" '-= ulhlclws on Rvm VS ass Fund -ed rdllet "HIE IRVLV,,,,! ... ONE, .p Y .M W n-z Died %

D, I !_ v sl uddfng .lricwnmiaw:,l 1111)11 VC PS"eviubps..!,. FD~A i I - : L BY lb- . I y,. -h: L "-P - lypc PA = 11,11" AY MIA V' 5T ""'1111A 'vandxnmina much nub _""'d-

Table 1. Continued Cuss PM M, Carom Sagmcnls PFOor,(SD Other Cardiac Age at Operation. Surgmi Pnxedurc :md No . Age.' Gender and Chenbo Imml Tricuspid Valve VSD1mm) GrimArtcrus Findings Clinical Coarse B. Right-Sided Milral Atresiu

21) A54d81 .5Yc TEA,{S .L.D} . 4SD2'(Rx14) EnlirelyImoLV.rdaimmissuml, BVFCpuotCS MildsuhPS Noopcntion.4'Cyr.developedmvereCHF yn F RAE. uhv:nt .-he., on LVaapl and m.1115 x 121 wish peripheral edema-usciles and Sinai Rv sinus, LAE. PMPM. redundsm c thick Its. amEythmias . V'0 :, : cardiac ones) during LVH+E TR cash, recovered. Died at home attar u rspiratory infection . 21 AOG37 . TEA, {S,-D(, ASD2`, Entirely into LV.tricommiswml, BVF 16 a 7) Urge MPA, PDA Ncopemtion. Treated tenCHF . Developed VF 3 week, M RAE. 010001 (12 . 1111 amebas on LVsep1 and PMPM Ao isthmus during each. Cardieroond. Died the next dayy RV siwr, LAE. hypnpl LVH+E 22 Living, TEA.{S .LL}. ASD2' Entirely mto LV, mcommsmral, Large MPA band 5'h. anal : PAR, heart failure and growth 4%ryr M RAE. atecul redundant, mild TR reslridiva improved. Pos top oath at 4 yr showed Rv sin BVF mums) PA pressure and arterial 0 . LVH+E saturation 8931.4.9 yr: fl-Wed Fonlan c rcevenlful recovery . 23 Living, TGA,{S,LL}. Rcariclive Entirely into LV,trioommssural Large, AVCtype MP.lbund Pnmo :surgalASD(BIalenk.Hanlon)and IS yn F RAE.alrem PFO atluchesonLVrrecwallund PAD, heap failure improved, remained RV sinus, LAE, --an of VSD cyanotic . 31VC y r. BT shunt modified, &, LVH+E yr : each: LVED = 6, PA = 12, nonrenrzi VSD . aT chum occluded, MPA ecnnewn, direct anasmmosin of RA with RPA, • vcntful rcwvery . IS yr: asymptomatie . repair. 24 Living . SGA.{S .L,L}. Restddive Entirely lot, LV,trieo xsurol Rcarklive BVF MPAsevore Woo, PDA ligated 2 days and again at l mo : coarcI 8 days : toy, M al almchmmm, PAR 4 ma: ASR_ 345: yry oath shows 60 RA.ab5ent PF0 Mil, oars grsdient atP MBVF. 4YrI, yn anaalomosis of repaired lmnseened MPA to asaading aorta and modified Fontan . Diuretic dntgs sad digondn for 2 yr. At present dningwell. 25 Living, DOill, {S,LL}, Nonrestrictive EnlirelyinloLV.large, Nonresleelive PS and severe 1 11 to 5 yr: ryallmic, decreased stamina. 5 y r: 33 yr,M RAE, absent PFO crompmenl.numberof BVF suSPS • rrent brain abscess, R hcmiparesis . RV sinus, LAE. clan mtssums nor determined ,hum s. SM. yr. L BT shunt. 16 yr: R BT LVH+E .33 ye markedly cyarmed. Her 70%, al CHF. CathRA= I1, LA = 11, LV = 145/18PA = 12, ferevmted Fm- c d-4. impnwementofeyannsrand stamina.

'Age at death for the postmortem cases and present age for the living patients . All pressures in mm Hg; all dimensions in cm . ALPM = ealerolateral paoillary muscle of the LV ; ant = anterior; Ao = sonic ; AmV = aonicvalve ; APM =anterior papillary muscle of the RV; ASD=atria) septal defect;ASD2a =secundum alrial sepml defect ; ASR= atria) septal resection ; AVC = atrioventrieularcanal; RC= bmchececphalic, bil=bilateral; BT shunt = Blalock-Taussig shunt ; BVF = hullxwentnealar foramen ; c = with; cash = cardiac cathetenzarion; CAVC = common aeciovemricular canal; CHF = congestive head failure ; coarct = coarcladen of aorta; car = coronary; CoS = co onary sinus ; CS =anal septum; DCRV = double-chamber right ventricle ; DO inf = double-outlet infundibulum; DORV )S,D,D) = doubleoulkt right ventricle with solims aria, D-ventricular loop and Dmalposed aorta; E = enlargement; ER = emergency room; F = female; Hot = hematocril; hypopl = hypoplastic or hypoplaeia ; IAA= interrupted Ionic arch; Iof = iofundibulum ; Ins = innmninate vein; L= Iof ; LA = laR atrium; LAE = left aerial enlargement ; LAH = left aerial hypertmphy; LCA = left coronary artery, If = leafkgs); LPA = left pulmonary artery ; LSVC = left superior versa cave ; LV = left ventricle; LVE = left vemrcular enlargement ; LVED = left ventricular end-diastolic pressure ; LVH = left vemrcular hypenmphy; LVsept = felt ventcular soared surface; M = male; and = malaligmnent; MPA = main pulmonary artery; obstr= obstructed; 0, = oxygen; Osat = oxygen saturation; PA = pulmonary artery ; PAR = pulmonary artery band; PAT= paroxysmal aerial tachyeardir; PDA= paten) ductus arteriosus; PFO = patent foramen male; plasry =valvulophsty ; PM = postmortem ; pro = papillary muscle( .); PMPM = poslernmedial papillary muscle of the LV ; postop = postoperatively, PPM = posterior papillary muacle(s) of the RV ; PS = pulmonary valve smnosic; R = right ; RA = right atrium ; RNA = right a trial appendage; RAE = right uoial enlargement ; RAH = right aerial hypertrophy; RPA = right pulmonary artery ; RPVs = right pulmonary vetm . RSVC = right superior a; RV = right ventricle; RVFW = right venrcular free wall ; RVsepr = light venelicalar settled surface ; SBE = subacute banerial endocardifis; {S,D,S} = solitus atria. D-loop ventricles, solbus normally 'l'ied greatarteriesa ; sept I' = septum prim m; {S,L,E) = solkas atria, L-loop ventricles, Dlransposed or malposed aorta ; {S, L, L} = solitus atria, L-loop ventricles, L-Bansposed coma : subAo = subsonic; subPS = subpulmonary stenosis; SVT = supmventricular tachycardia; TGA = transposition of the great arteries; TR = tricuspid regurgitation ; TV = tricuspid valve; VF = ventricular fibrillation ; VS = ventricular septum ; VSD = ventricular septet defect: underdev = underdeveloped ; unicorn = unkommissuml;-r = imo.

Vol l . 19, No. 7 SHINTO ET AI. . 1555 flatloot 1992 :ISb1-76 MI r KAt. A IAESIA WITH A LARGE LITT VENTRICLE

single L-looped left ventricle to the rghi and posterior of a the atrial septum met the AV groove and by observing the left-sided double-outlet infundibulum . atresia of the right- distance between the needle and the posterior end of the sided mitral valve and dextrocardia Echocardiographic ventricular septum . The direction of the needle was perpen- study of this patient was considered unsatisfactory because dicular to the posteroinferior (diaphragmatic) surface of the of very poor imaging windows . He was the oldest patient in heart. this series and the only one with dextrocardia . The reruriealar .septal defect was assessed in all cases The ventriculoatrial malalignment in 12 of the 15 postmor- according to its position in the left ventricular septal surface, tem cases was the subject of a brief presentation in the its size and the presence or absence of straddling of the Second World Congress of Pediatric Cardiology (8). One of tricuspid valve . A large ventricular septat defect in the inlet these postmortem cases was also reported (9) as an example portion of the left ventricular septet surface associated with of subaortic stenosis recognized after banding of the main a straddling tricuspid valve was described as a ventricular pulmonary artery . septal defect of the AV canal type (3,9-11) . This defect There were 16 male and nine female patients (ratio 1 .11 :1) . resembled the ventricular septal deficiency seen in hearts Because the right-or left-sided position of the Kinetic mitral with a common AV canal, in that it extended over the entire valve has different hemodynamic consequences, we sepa- width of the ventricular septum and the left ventricular rately calculated the range and median age at death in each septa[ surface had a shorter inlet than outlet dimension of the two groups . In the I 1 postmortem cases with left-sided 111 .12). It differed from the AV septal defect in cases with a mitral atresia (D-loop ventricle) . the median age at death was common AV canal in that it was not associated with a 2 months (range 2 days to 12 111/r years) . In the four postmor- common AV valve or an ostium primum septal defect, or tem cases with right-sided mitral valve atresia (L-loop ven- both (Fig . ID and 2B) . In addition, probably because of the tricle), the median age at death was 41/Is years (range 21 days underdevelopment or absence of the right ventricular sinus, to 27 years), the posterior border of the ventricular septum did not meet Anatomic evaluation, The atrial sifts in the postmortem the crux or the heart as it does in cases of a common AV cases was diagnosed on the basis of the systemic and canal . pulmonary venous connections, the relation of the septum A rentricolar septat defect in the area of The owlet primum to the septum secundum (when the septum primum ventricular septmu, usually small and never associated with was not surgically resectedl and the size and shape of the a straddling tricuspid valve, has been described as a butbo- atria] appendages. In the IO living patients, atrial situs was ventricular or infundibuloventricular foramen (that is . a defect diagnosed on the basis of the echocardiographic or angiocar- allowing communication between the infundibulum [the em- diographie appearance, or both, of the systemic and pulmo- bryonic bulbus cordisl and the left ventricle) (Fig, 3, B to D and nary venous connections . and was confirmed in all by 4, B and CI . When this defect was confluent with or close to the surgical observations . aortic valve, it was also described as subaortic. The type of rentricrdar loop present was diagnosed in all Enlargenrene and hypertrophy of the cardiac chambers in cases according to the position of the left ventricle in relation the postmortem cases were evaluated by comparison with to the ventricular septum . It was concluded that a D-loop the normal heart of persons of the same age. In the living was present when the left ventricle was to the left and patients, atrial and ventricular enlargement was assessed on posterior to the characteristic left ventricular septal surface. the basis of electrocardiographic (ECG), echocardiographic An L-loop was considered present when the left ventricle and angiocardiographic data . was to the right and posterior to the left ventricular septal Tile ight ventricular sinus was considered absent when surface. Because this surface can be recognized echocardio- the tricuspid valve was entirely left ventricular (Fig- 3B and graphically (10), the same criteria were used for 9 of the 10 4B) . living patients . In one living patient (Case 25, Table I I with Clinical evaluation. Hospital records were available for an unsatisfactory echocardiogram, the diagnosis of the ven- review in all patients . Chest X-ray films or reports and at tricular loop was based on the findings on his angiocardio- least one ECG were available in all but one patient (Case 1, gram . Table 1) . Echocardiograms with Doppler studies were avail- The patent AV calve (t/tat is, the tricuspid ralre) was able for review in 9 of the 10 living patients . evaluated for leaflet morphology (normal, redundant or Cardiac catheterization data were obtained in 12 post- thickened with rolled edges indicative of regurgitation) . mortem cases and in all living patients . papillary muscle attachments (entirely into the left ventricle, on the crest of the ventricular septum, straddling the ventricular septum or attaching on both ventricles) and the Results number of its commissures (postmortem cases) or points of Anatomic findings (Table 1, Fig. I to 5) . The 25 cases chordal attachments (living patients) . included in Table I are arranged according to 1) the type of The position of the ventricular septam (inlet portion) in ventricular loop (cases with a .1oop0 with left-sided mitral relation to the crux of the heart was determined in the 15 atresia precede those with an L-loop) : 21 the type of ventric- postmortem cases by inserting a long needle at the site where uloarterial relation (cases with normally related great arter-

JACC In . No .7 1 566 SHINI't) CT AL . Vet . WE RAI . AIRRSIA WITH A LARGE LEFT VENTRICLE: Juae 1992..061-ru

Figure 1. Case 7. The heart of a 23-day old boy with solitus atria . precede those in which the tricuspid valve is entirely in the D-loop ventricles, D-transposed aorta . mitral atresia. a straddling left ventricle) . tricuspid valve (TV) and pulmonary atresia. A . The opened right Left-sided mitral atresia and normally related great arter- atrium (RAI is very large . AS = surgical atrial septa] defect . III, The tricuspid valve straddles the ventricular septum and attaches on the ies were present in Cases I to 5 . Left-sided mitral atresia and free wall and the septa) surface of the small . underdeveloped right a double-outlet right ventricle or transposition of the great ventricular sinus (RV ). The opening of the Waterston anastomosis is arteries were present in Cases 6 to 16 . Finally, right-sided seen in the wall of the ascending aorta lAo) . CS = canal septum : mitral valve atresia and transposition of the great arteries or SB = septa) band . C, A small left atrium with worked hypcrtmphv a double-outlet infundihulum were present in Cases 17 to 24 . of its wall and the wall of the pulmonary veins IPVsI has the surgically created atria) septa) defect (ASD) as its only exit . The In all of these subgroups. the postmortem cases precede the left atrial appendage (LAA) and atreli,: mitral orifice (M All are living patients . seen . D, Opened left ventricle (LV).'the tricuspid valve straddles The left veatrlrle it-as either of normal size or enlarged the ventricular septum and attaches only to the posteromedial (VS) (Teth(r 1) . Left ventricular hypertrophy was present in 15 papillary muscle . The anterolateral papillary muscle is represented patients (60%) (Fig. ID. 2B . 3C and 4C). by the trabeculations seen in (he free wall (RV) of the left ventricle . The main pulmonary artery IMPA) is small but patent down to the The right rrabirulor sieos was absent in 14 cases (56%) level of the atretic pulmonary valve (P An . This wax the only case )Fig. 3B and 411) and underdeveloped in 11 (44%) (Fig. IB in this series with congenital pulmonary valve atresia . and 2C). The posterior limit ofthe inlet ventricular sepumn did not meet the crux of the heart in any of the 15 postmortem cases . ies precede cases with transposition or t double-outlet right It was located to the right of the crux in all the patients with ventricle) ; and 3) the presence or absence of straddling of the a D-loop ventricle and to the left of the crux in all the tricuspid valve (cases with a straddling tricuspid valve patients with an L-loop ventricle .

IA('C vat. IV. Na 7 SFn\i't El AL. 1 567 lame 1-- :15X1-7n gIIKU \IKI:FIIII'llll\L\nGP:l .liIi1-fiat"I

Figure 2. Case 17. The heart of 27-roar old man with olim atria, L-loop venhricles and an L-lrmspoceJ aorta . A, Opened right atrium IRA). The right-sided mitral calve onfice is urenc INI At IRIt. PFO = patent foramen ovals . e, Opened right-sided left ventricle (LV IRI). There is hvpern ophv of the left ventricular free wall IFWI . The ventricular septum IVSI display's the charac- tefisiic smooth surface and a large atriovenuicnlar canal type ventricular sepud defect . The Tricuspid salve l IV) . which allots, communication between the left atrium and left ventrice, is tort abnormal . II attaches on a very wide multiheaded posterior papillary muscle and on the posterior pare of the Iowa rim of the large ventricular .:eplal defect . The edges of the tricuspid value arc Ihick and rolled . indicative of significant tricuspid regurgitation . The pulmonary valve (PV) is in direct fihrous continuity with the tricuspid valve . C. The extremely underdevelupal right ventricular sinus (RV) and infundihulum Iloll are lefl-sided and show marked hvpcnrophv . The left-Wed tricuspid stdro straddles the posterior part of the lunge ventricular septal defect and apaches to the right ventricular serial surface. The aorta IAol originates from the infundibulum .

The single parent AV' i ahr ams rrironurtissurel by post- all ial septal defect. or birth. The severity and onset of heart mortem or echocardiographic assessment in 11 patients failure were also unrelated to the left- or right-sided position (RR%) (Table I, Fig . 2B : 3 . C and D: 5. A and C . and 6) . Its of the at, tic mitral valve . leaflet and papillary muscle attachments were not like those Chest V-ran films were available in all but one patient of the mitral valve in cases at' tricuspid atresia (Fig. 71 . nor (Case I . Table II . All chest X-ray films showed mild to were they like those of the normal right ventricular tricuspid mm"ked cardiac enlargement . The vascularity of the lung valve . The leaflets tended to be redundant . with papillary fields was increased in 19 (79%I of the 24 patients with muscle attachments varying from case to case . When the available chest X-ray studies . valve straddled the ventricular septum, it straddled through Flit rrw'urdiograms were available in all but one patient a ventricular septal defect of the AV canal type and inserted (Case I Table I L All 24 patients with an available ECG had into the underdeveloped right ventricular sinus, the crest of normal sinus rhythm when first seen at The Children's the ventricular septum and the posteromedial papillary mus- Hospital . Four patients (two in the group of living patients) cle of the left ventricle (Fig . I . B and D: 2. B and C : 5 . A and developed atria) arrhythmias . C . and RA). The papillary muscle attachments resembled All 24 patients had very prominent P waves indicative of those of a straddling tricuspid valve with a patent (normal or right atrial enlargement in the standard and precordial leads . stenotic) mitral valve (Fig . RBI. A superior frontal QRS axis and a counterclockwise vector Clinical profile. Cyanosis was universally present . Its loop in the frontal plane were present in five of the seven onset or severity was not affected be the left- or right-sided patients with a D-loop ventricle . a straddling tricuspid valve position of the alretic mitral valve . and a ventricular septal defect of the A V canal type (Cases 2, Near) (iuilure, often with particularly severe dyspnea due 3.6 to R . Table 1), Similar FCG findings have been reported to pulmonary venous congestion. was observed in all pa- t11) in patients with a straddling tricuspid valve . mitral tients who did not have significant pulmonary stenosis or an stenosis and D-loop ventricles.

IACC VII . 19. Nu. 7 1588 SHINTO FT AL. 7 MITRAL ATRFSIA WITH A LAR(iL: LFFI' VENTRICLE. June 19921551_ 5

Figure 3. Case 13. The heart of a N2-year old boy with arial sitar In the cases with the tricuspid valve opening entirely in solitus . .loopD ventricles, Ieh-sided mural 1 .trvsia (M At) and the left ventricle and an outflow ventricular septal defect and D-transposition of the great arteries . A, Opened left atrium . The in all the patients with L-loop ventricles and right-sided wall of the pulmonary veins (PVc) is markedly hypertrophied . mitral atresia, the frontal QRS axis ranged from 45' to 120' A surgically created attial .sepia] defect (ASD) is present . Coronary sinus (Co SI orifice atresia has resuftl in a dilated coronary and the vector loop in the frontal plane was clockwise . In the sinus . LAA = left atria) appendage . B, Opened infundihular majority of patients, the precordial leads exhibited an rS or chamber (Inil, The transposed aorta lAo) and bulboventricular RS pattern. foramen (BVF) are seen . Opened left ventricle (LV) . The . C EC/tocesrdiogrants with Doppler interrogation were avail- tricuspid valve (TV) is entirely left ventricular with three chordal livine patients (Cases 4, 5, 9,10.16, 19 and attachments and three leaflets . Two of its attachments are to the able in 9 of the l o anterefaterai and posteromedial papillary muscles of the left 22 to 24, Table I). The echocardiogram of Patient 25 was ventricular free wall and the third one is into the conal septum . considered unsatisfactory because of poor imaging windows. A very small membranous pouch is identified close to the left The echocardiographic studies accurately demonstrated ventricular free wall and under the atretic mitral orifice . It the atrial sites, the ventricular loop, the site of the Arctic represents the abortive mitral valve IMVI. PV = pulmonary valve . mitral valve, the morphology of the patent AV valve, the D, Magnification of the tricuspid valve and its attachments . a s well as the membranous pouch representing the mitmi valve . CS = copal size and position of the ventricular septal defect or defects, septm. the presence of pulmonary valve or subpulmonary stenosis

tALC VA . 19 . 1, 1 SHINPO ET At.. 1569 June 1997.1%1-'5 SIIIR.-V . ArarAlA WITH A LARGE LEFT VENTRICLE

Figure 4. Case 14. The heart of a 127c-r, old buy with solitul atria. D-loop ventricles . left-sided mitral atresia IM At) . D-Imnspo- silion of the great arteries and subpulmonary stenosis . .A Opened left atrium (LA), displaying a surgically created atrial sepal defect (ASDI and the attachments of the septum primum to the left arild septa) surface. B, The interior of the infundibular outflow chamber (InfOC). The aorta (Act and bulboventriculer foramen (BVF) are seen . C, Opened left ventricle ILVI . The tricuspid valve (TV) is entirely left ventricular, with chordal attachments to the posteromedial papillary muscles and an abnormally small and posteriorly located anterolateral papillary muscle . The thickened rolled edges of the anterior commissure reflect tricuspid regurgitation, which clinically was severe. Posterior conal seplal malalignment :md a prominent free wall IFWI trabeculation produce subpulmonary stenosis (PS( . Ao V = aortic valve ; VS = ventricular septum.

and the type of ventriculoarlerial relations . In three of the hypertension was found in three patients with left-sided echocardiographically studied patients, a straddling tricus- mitral atresia despite the coexistence of subpulmonary or pid valve was observed (Cases 9. 10 and 19). Doppler pulmonary valve stenosis (Cases 5, 14 and 16). In two of interrogation revealed moderate tricuspid regurgitation in these patients (Cases 5 and 16). pulmonary artery pressure Cases 9 and 19. The youngest of our living patients (Case 10) was found to be normal during cardiac catheterization I year had a competent straddling tricuspid valve . In the remaining after atrial septectomy . Patient 14 did not undergo cardiac six living patients, the tricuspid valve was large- entirely left catheterization after operation . ventricular and had redundant leaflets . Careful review using The patients with right-sided AV ralvc atresia who had slow motion and stop fratne analysis revealed three points of recently undergone cardiac catheterization (Cases 18, 19 and attachment (Fig. 6) . In four of the six (Cases 4, 16, 22 and 22 to 25) were correctly diagnosed as having mitral atresia 24), Doppler interrogation showed mild tricuspid regurgita- with a large left ventricle on the basis of the echocardio- tion . All four patients were >3 years of age when tricuspid graphic appearance of the patent AV valve and type of the regurgitation was first observed . ventricular loop present . Cardiac catheterization . This was performed in 24 of the Regurgitation of the tricuspid vah,e was detected angio- 25 patients (Cases 2 to 25, Table 11 . On the basis of the cardiographically in sc -veu patients (Cases 3, 4, 8, 9, 14, 16 catheterization data alone, the correct diagnosis of mitral and 24), three with a straddling tricuspid valve . The young- valve atresia was accomplished in 12 of the 16 patients with est patient with angiocardiographic evidence of tricuspid a left-sided atretic mitral valve . Patient 3, who underwent regurgitation was 3%Iryears old . cardiac catheterization in 1973 . was erroneously diagnosed Atresia of the coranarv sinus orifice and retrograde flow as having a common AV canal instead of mitral valve atresia of blood into the left superior vena cava, innominate vein, with a straddling tricuspid valve . right superior vena cava and right atrium were well demon- Pulmonary artery hypertension due to pulatottaev venous strated by angiocardiography in Case 4 (Fig . 9) .

Vol. 19 . Nn. 7 1570 ..HINW11T AL . isec \71TRA1 . AtahS1A WITH A Aver III'' VINTRR 1 1: June 199'- .1551- 76

Figure 5. Case 2. The heart and lungs of a 2'h-month old boy with solitus atria. D-loop ventricles and normally related great arteries, left-sided mitral atresia and a straddling tricuspid valve . A, The right an'ium (RA) communicates with the large left ventricle (LV) and the small right ventricular sinus (RV) by way of the straddling tricuspid valve 0'V) . The ventricular septum (VS) is transected at the level of the ventricular sepml defect, so that the right ventricular attachments of the tricuspid valve can he seen . B, The left atrium has a dimple on its floor, representing atresia of the mitral orifice IM Al( . The wall thickness of the left atrium is markedly increased. The left atrial appendage (LA) is distended and points posteriorly. The atrial septum is intact. LL and RL = left and right lungs . respectively . C, The outlet of the left ventricle (LV) toward the aena is widely patent and there is direct fibrous continuity between the straddling tricuspid valve (TV) and the aortic valve (AoV). VS = the crest of the ventricular septum .

Balloon atrial .septostonnv attempted in two patients In embryos with a crown-rump length of 6 mm . "the (Cases 4 and 11) was unsuccessful . Blade atria] septotomy atriuventricular canal still gives access only to the primitive followed by KO',) m dilation in four other patients (Cases 5 . left ventricle and is separated from the cones cordis by the 10, 16 aid 741 ::riled to eliminate the pressure gradient bulbo- (cono-) ventricular fold . With further development, between the left and right atria . All four patients subse- the central portion of This fold recedes and blood can now quently underwent surgical atrial septectomy . In the post- enter the primitive right ventricle directly from the atrium" mortem cases, examination of the septum primum indicated (14) . Another factor that has been considered to contribute a markedly increased thickness so that it could not be torn to the approximation of the right atrium with the growing by the balloon . Blade septotomy may succeed in incising the right ventricle is the expansion and rightward movement of septum primum, but the markedly increased septa ; thickness the AV canal (13) . limits its mobility and consequently the effectiveness of the Underdeveloped or absent right ventricular sinus . In ad- septotomy . In addition, the cavity of the left atrium in the dition, we and other investigators (7) think that the growth of very young patients is often small and the risk of incising the the right ventricular sinus plays an important role in the final atrial free wall is very real . normal alignment of the atria with the appropriate ventricles . This view is supported by the anatomic finding of AV malalignment in several cardiac malformations in which the Discussion right ventricular sinus is underdeveloped or absent . Because Developmental and Morphologic' Considerations movement of the AV canal is limited by the relative immo- It is generally accepted that after ventricular looping, the bility of the atria, which are "anchored" by the systemic and undivided AV canal is entirely located above the primitive pulmonary veins. the approximation of the tricuspid orifice ventricle, which is the precursor of the morphologically left and right ventricle is probably influenced more by the growth ventricle (13-16( . of the right ventricular sinus and the resulting leftward shift

1AC(' Vat. iv . No. 7 tiN19PU1;r- 1 57 1 Jlmc 10)2 :I]M1I-7v 51110 V . i7iIISIAwrrll :\ 1, AKGr rrFI VP.NIt,III I

ventricular septum is deficient . the tricuspid orifice is placed .ho" both ventricles and the tricuspid valve exhibits biventricular papillary muscle attachments . Role of straddling of the tricuspid valve . Depending on the degree of the straddling of the tricuspid notice, the mitral valve orifice may be displaced close to or exactly above the left ventricular free wall . resulting in mitral stenosis or atresia. In other words, a straddling or left ventricular tricuspid valve often interferes with the normal development of the mitral valve . which may become stenotic (II) or atretic (3) . In the cases in this series . underdevelopment of the right ventricular sinus was associated with marked AV malalignment and alignment of the tricuspid orifice entirely or pertly with the left ventricle . The dimple of the atretic mitral valve orifice in all our postmortem cases was above the left ventricular free wall (Fig . 10), Because the tricuspid orifice remained partly or completely above the left v entri- cle . i t allowed blood flow to stimulate normal growth . This resulted in the apparent paradox of mitral atresia with a normal-sized or large left ventricle . Atrioventrieular valve identity . One might have expected the left ventricular tricuspid valve to have the morphologic features of the mural valve (Fig . 7). but this did not occur in the patients in this series or in previously reported cases 11-4 .( .7) . The left ventricular tricuspid valve remained sep- tophilic and usually attached to papillary muscles close to the ventricular septum or to the lower rim of the ventricular septal defect or to the tonal septum- or both (Fig . I- B and D: 2 . B and C: 3, C and D : 5 . A and C . and 8A). When this single AV valve straddles the ventricular septum, it is always through a ventricular septa) defect of the AV canal type as has been observed with the straddling tricuspid valve (17) (Fig . ID : 2 . B and C, and 8A) . In contrast. the mitral valve is known to straddle through an Figure 6. Case 4 . Echocardiogram from an 8-year old girl with outflow ventricular septa) defect due to conal septa) mal- solims atria . D-loop ventricles. normally related great arteries and alignment (17). Hence . although the leaflet morphology of left-sided mitral atresia . Subxiphoid short-axi, views in diastole (A) and systole 1B) show the tricuspid valve (TV) in the left ventricle the partly or entirely left ventricular tricuspid valve has (L V) . Note the three ccmmisemes of the tricuspid valve (arrow- some similarities with the leaflet morphology of the mitral heads) . The large inlet ventricular septa) detect (VSD) is seen in vaive (probably for hemodynamic reasons) . its mode of diastole . p = posterior: s = superior. straddling and papillary muscle attachments are not like those of the mitral valve (Fig. 7) . These anatomic facts led us to conclude that the true of the ventricular se plum than by the rightward movement of nature of the AV valves is expressed in their papillary the AV canal. Thus, it is not surprising that in all the muscle attachments and proximity to the ventricular septum, malformations that share the characteristic of nigh: ventric- rather than their leaflet morphology . Our data also indicate ular sinus underdevelopment (double-inlet left ventricle, that, as a rule . the right- or left-sided position of the tricuspid straddling tricuspid valve with normal or stenotic mitral valve depends on the type of the ventricular loop that is valve, tricuspid atresia with normally related or transposed present (that is, the tricuspid valve is right-sided in D-loops great arteries and mitral atresia with a large left ventricle), and left-sided in L-loops), In addition, the cases in this and the inlet ventricular septum does not meet the crux of the other reports (1-4.6,7,9) support the conclusion that the heart. On the basis of the anatomic findings of these cardiac identity of an AV valve does not always depend on the malformations, it appears that if the right ventricular sinus identity of the ventricle that receives it ; otherwise, one does not develop after ventricular looping, both AV valve would have to postulate that in the hearts with a double-inlet orifices maintain their early embryonic position above the ventricle . the two AV valves are both mitral and that a primitive ventricle and double-inlet left ventricle results. If straddling tricuspid valve has tricuspid and mitral compo- the right ventricular sinus is partly developed and the inlet nents .

. Hu .', 1'72 0I11N1O 11 AL . la('[' 1'rl . Iv M1fo41M vrm-SIA o,I1'H 41 .00111 : Lfl'1 'I . .vtlfl I I acme 114+ .151,1=1•

'igure 7- A, Gee 57'-1)6 . 1 he leant of a1 4 1 yc-veal ofd her k lh hear) rite "shadow ' of the mitral'active that tamed Ut develop ohms mina, D-loop vwirisicp. Ddmndpasnd 111cul 'artrca and (Fig. 1DI, Its prcuence stteurtthens (lie conelnvilrn that the fight-sided rrinrspid atre+i, . Opened Ielt-sided Ief1 se01111Ie 11-VI relent AV vdve is the tricuspid valve . hoses marked hvpcrtrophv .1 its trio well (l-W 1 and the popi€lira' nuccles of the normal milrul valve [MV] The in flmdlhulosen!licii u' foramen [IVFI Ks Iron surgically enlnreed . PV = pulma iv 1-0 cave'. VS = ventricular ,puma If . Case A51-'-U . tie heir: u kiguruNA .Cece8 .Thenpunod cftveniricleofa94c-yaanddtmv 4-henrold hoe with .lita, carol . L-1-1p cemticles- I : nimspua•,1 ,iii- ;ulnas clha- lehaidod initial uacsia . D-loop venlricler :md'a red arteries and a lull-tilled ;102114 Iricaspid oriEci lt= lifhl drools-eudcl right vrnn'iele with a D-m :dposed auna. The snarl Lou communicates N'ith the ilghhsided leis venlrdu IL VIhh A III Iri :wpic'amts IINI Htmehcs 111 the miller rim of the large in Io111141 nphl-sided mural o' ilve I hVlOil erhlhilr the usual normal ven'deticr sep'l,al tenet 1V .5DI of the ausuvemricular IAVI canal nachmems an the too papillay muscle snaps of the lice .all of type and o the pesrsomedial papillary muscle of the loft ucniricle he left venlncle . The inl'uuiihnlourmriculur foramen is 11011 ldc- ILVI. Sole the thickened cdgesoftlu Iricuspid salve indiculivr of c and can ba seen to the tell tdthc pnnnepull Pal illurv I11selc, r[urgifaliun . fW = fee oval : VS = ccn .ricular septum . It. The -he left ventricle is en1mgcd'and hypertntphied, Soft I - 11,11 cpeaeJ efveiIClu'Ifa25.manIholdcirlwitinAultipleconpeniIal 4imum . enunalini viscn',J heteretazyi tuAv,rlenia . ;.liras atria, D-loop vin :ticles sand nurmafly 'dated great urtcrio.. The aneurysmal vmdTing '.ricuspid rata's is attached In the crest of the large AV loin ventrieuhc'septal detect and the posteromedial papillary ""RImamlc of the loll ventricle . The milrnl valve is hypoplarlfc and In Case 1} in this series (Fig . q . the thint In-n-, rot or ShTrlic 1 Vi 51 anti its lc;ittrlo are fined with tell scrilrirolar fit' wall he left ventricular tricuspid valve mimics a clef" of the tnofceahtlinn, lair the al11eIim papillary musclel . None II€ : mi ni ladly nlcrior leaflet of a mi1ral valve . Careful obxrvalicn irJi- lil'11t vcnlriatlar septul detect and Ills nnpillon• allachmtems of the ales that Ibis cleft hair cllurdul altachoiculs to the runal alr•¢idlike teieusp€d solve to the case shown in A . In both cases . the opium instead of the most inferior par[ of the told vznitic- trines pillvalve Leached to the free wail and ventricular septum I VSI ufa slighllr underdeveloped right ventricular ,mw tnot shown l. We dar sepmm . In addition . there is a, very small membr naus sp_aahtle'.hat a similar mnrphopcnclic process differing only in couch below' the atrelic left all ii outlet and adjacert to ale dcurvc twilled in mitl :d .11-11 11a the cave in Amid IN1ml daemon ell vemricu!nr free wall that must represent in this D •I nnped in tie case In It .

JACC Vet, 19. No . 7 SHR7PU FT AI .. 1 57 3 lone 1952:ISrd-7a ivross ITRFSI :xWITH5 nefFLFFTvENTRICLF

the mitral valve attached on papillary muscles originating from the free wall of the left ventricle (Fig . 7). We also found than the right- or left-sided position of the sepiophilic AV valve (that i,, the tricuspid valve) in the 55 cases of double- inlet left ventricle accurately predicted the type of venivev- lar loop present . 1-lern e . the nuaehnrenrs of the AV rah'e ar rnlres and the tvpe of the remriralar septal defect drrmigh whit -It the i n/i'e straddles can be used to diagnose the ideniny of the AV valve or valves . In addition, as a role . a right-sided tricuspid valve is indicative of D-looped ventricles and a left-sided tricuspid valve is indicative of L-looped ventricles. Conse- quently . identification of the AV valves can indirectly diagnose the type of ventricular loop more accurately than can the position of the infundibular outflow chamber or the position of the transposed aorta . By using the same principle in reverse . i t is possible to diagnose the identity of the AV valve or valves when the ventricular loop that is present is known . We found that these conclusions apply accurately to hearts with two ventricles. as well as to hearts with a single left ventricle, excluding some very rare cases with atrial and Figure 9. Case 4. Selective innominate vein angiocardiogram (an- ventricular valpositinr ssnciated with juxtaposition of the teroposterior view) from a patient with atresia of the coronary sinus atrial appendages (18-20) . ICoSI orifice and a persistent small superior vera cava . Contrast Tricuspid and mitral versus left and right AV valves . The material fills the innominate vein . left superior vena cava ILSVC) . atypical leaflet morphology of the AV valves in double-inlet part of the coronary sinus and two large cardiac veins (CVI . The left ventricle and cases of mitral atresia with a large left extension of the coronary sinus toward the right atrium and its estium were never visualized . Blood flows in a retrograde direction ventricle tempted us and other colleagues (21-28) to use the from the coronary sinus to the left superior vena cava . innominate terms right and left AV valve, rather than tricuspid and vein. right superior vena cava and finally into the right atrium . A mitral valve. This approach gave primary concern to the clamshell device used to obliterate a large patent due uuureriosus is hemodynamie consequences associated with atresa of tine seen under the junction of the left superior vent, cava and in-mi . right or left atria] outlet rather than to the identity of the note vein . atretic valve . Yet the findings of this and other studies (10) indicate that AV valve identification is almost always possi- Papillary muscle attachments. We compared the papillary ble by echocardiography in living patients and at postmor- muscle attachments and the type of ventricular septa) defect tem study in heart specimens . in cases of straddling tricuspid valve with mitral stenosis Hence . we propose the use of the terms tricuspid or with findings in the cases in this series with straddling mitral atresia- rather than right or left AV valve atresia . tricuspid valve and mitral atresia (Fig . 8) . The observed when one of the two AV valves is atretic . As other investi- similarity favors the conclusion that both malformations gators (2_91 have pointed out . unnecessary simplification of result from a similar morphogenetic process . varying only in terminology creates a situation where "the material becomes the degree of AV malalignment and the degree of the less accessible to those who try to understand the develop- resulting approximation of the mitral valve orifice with the mental background of cardiac malformations ." free wall of the tell ventricle . The straddling tricuspid valve In the cases in this series, a clinically important consid- with mitral alresia or stenosis presents certain similarities in eration aided by accurate AV valve identification is the its papillary muscle attachments with a common AV valve . realization that in this unusual type of mitral atresia, the Yet the absence of a foramen primum type atrial septa) partly or entirely left ventricular tricuspid valve is often defect and especially the presence of an atretic or stenotic incompetent or may become regurgitant even when it is orifice at the expected position of the mitral valve strongly competent in early infancy . Although the overall incidence indicate that the AV valves are not in common . of tricuspid regurgitation in our 25 cases was 56%, 12 (86%) To further substantiate the septophilir and .septophobir of the 14 patients >2 years of age had echocardiographic, characteristics of the tricuspid and mitral valves . respec- engiocardiographic or anatomic evidence of some degree of tively, we examined 55 heart specimens with a double-inlet tricuspid regurgitation . In 6 of the 13 patients with tricuspid left ventricle and 72 heart specimens with tricuspid orifice regurgitation, the tricuspid valve was straddling (Cases 3 . 8, atresia from the Cardiac Registry of the Children's Hospital 9 and 17 to 19, Fig. 2. B and C and 8A). and in 7 it opened in Boston. We found that in all 72 specimens with tricuspid entirely into the left ventricle (Cases 4 . 13 . 14. 16, 20 . 22 and atresia (with normally related or transposed great arteries) . 24 . and Fig . 3- C and D and 4C) . lit contrast, the left

SHINTO CT AL, (ACC Vnl. 14 .N,7 1574 MI IAAL AIRESIA WITH A LARGE LEFT VENTRICLE lone IY4_iSM1 I-7n

Figure 10. Diagrammatic demonstodion of ventriculoatdal malalignment and abnormal venlriculoalrial sepia] angle in three postmortem cases . The normal angle between the ventricular (VS' and the atrial septum (ASI is approximately 10' . A. Case 3 . This patient had solilus atria, D-loop ventricles. normally related great arteries and a straddling tricuspid valve . The ventricular part of the hear! is malaligned far to the right relative to the atrial pan of the heart . The expected site of the mural orifice (x) is located above the left ventricular free wall (LVFW) . resulting to mural atresia (MAtt . The vcntriculoatrial septal angle is abnormally large (6ll°I . B, Case 12 . This patient had sulilus atria. D-loop ventricles . D-transposition of the great arteries and a tricuspid valve entirely in the left ventricle . There is marked rightward malalignmenl of the ventricular segment relative to the atrial segment . The expected site of the mitral orifice-the mitral dimple (xl-is located above the left ventricular free wall, reselling in mitral atresia . The eontriculoetrial septal angle is very abnormally large 170°1 . indicating that although the atria] septum LAS) was normally vertical. the ventricular septal plane was almost horizontal . IOC = infundihular outlet chamber. C, Case 21. This patient had solilus atria, L`leep ventricles, D-transposed great arteries and an entirely left ventricular tricuspid valve . There was marked malalignment of the ventricular part of the heart to the left relative to the atria . Consequently . the right-sided mitral dimple was located above the left ventricularfree wall Ix I. The ventriculoatrial septal angle was much larger than normal (60'). All three diagrams are analogous to short-axis two-dimensional echocardiographic views, the ventral surface being toward the top, the dorsal surface toward the bottom . the patient's right toward the viewer's left and the patient's left toward the viewer's right.

ventricular mitral valve in cases of tricuspid atresia (regard- surgeon can avoid the ligation of the left superior vena cava, less of the type of ventricular loop present and the type of which usually is very small. If the atretic coronary sinus ventriculoarterial relation), is very seldom regurgitant unless receives the major cardiac veins, ligation of the left superior it is cleft in association with a partial AV canal septa] defect vend cave can he fatal (35) . (30) . Atrioventricular and ventriculoarterial relations. Vis- Coronary sinus orifice or lumen atresia . The presence of ceroalrial silus solilus occurred in all cases in this series . atresia of the coronary sinus orifice or lumen in 3 of the 16 Hence, the 16 patients with D-loop ventricles had AV situs cases with left-sided mitral valve atresia represents a high concordance. In all 16 patients, despite the presence of AV (19%) incidence of this rather rare malformation (Fig . 9) silos concordance, the right atrium opened partly or com- (31-34). One wonders if the etiology of this defect is related pletely into the large left ventricle by way of the right-sided to the obstruction of the left atrial outlet so early in embryo- tricuspid valve, resulting in AV alignment discordance (Fig . genesis that the resulting high left atrial pressure compresses SA), In the patients with L-loop ventricles (that is . AV sinus and obliterates the lumen of the coronary sinus. The pre- discordance) . the left atrium by means of the left-sided operative diagnosis of this anomaly is important, so that the tricuspid valve opened partly or entirely (depending on the

JACC Vol . 19, Na. 7 SHINPO FT AL 157 5 June 1992 :1501-7G sit rcAL A[RrSLs WITH A I .ARGE LEFT vENTRICLE

presence or absence of straddling oft he tricuspid valve) into procedure (39) and bidirectional cavopulmonary shunt were the large left ventricle, resulting in AV alignment concor- performed in two patients (Cases 4 and 9, Table 1) . dance (Fig. 21. It is obvious then that in this type of Three patieats lCases 19. 23 and 24, Table II with a malformation, the segmental situs concordance (that is . right-sided atretic mitral valve underwent atriopulmonary anas- solims atria and D-loop ventricles) results in segmental tomosis 140) before the introduction of the more recent modi- alignment discordance . For the same reasons, segmental fications of the Fontan procedure (37 .38) . All three are alive, sinus discordance (that is . solicits atria and I- loop ventricles) acvanotic and have considerably improved exercise tolerance . results in segmental alignment concordance . Two additional patients with right-sided mitral valve atresia Cas es 22 and 25 . Table 1) . recently underwent a Surgical Considerations fenestrated Fontan procedure and had an uneventful recovery . Patient 25 (a 33-year old father of three and grandfather The surgical procedures performed in 17 of the patients in of two) had a dramatic decrease in severe cyanosis and this series are described in Table I . Several subsets of increase in exercise tolerance after the operation patients who died before 1973 were I) patients who were not . Cavopulmonary artery anastomosis. A most important surgically treated in = 8). 2) patients with atrial septectomy decision for patients with either left- or right-sided mitral or main pulmonary artery banding, or both in = 41 . and 3) patients with atria) septectomy and systemic to pulmonary valve atresia is the timing of the cavopulmonary anastomo- artery shunt In = 1) . All but 2 of the 12 patients who were sis . which is the final surgical therapeutic objective . The operated on after 1973 (Cases 8 and 18) are alive and single AV valve in the heart of these patients is the tricuspid improved clinically or hemodynamically. or both. valve with abnormal left ventricular or hiventricular attach- Atrial septectomy and pulmonary artery banding . When ments . The presence of mild or moderate tricuspid regurgi- the atretic mitral valve is left-sided. surgical atrial septec- tation in 86C3 of the patients >2 years of age in this series tomy is essential in early infancy . Case 16 is •a rare example must not he overlooked. Can the development or progres- of a patient with left-sided mitral atresia with a restrictive sion of Tricuspid regurgitation be avoided by performing a foramen ovale who grew normally and survived to the age of cavopulmonary anastomosis as early as possible? If some of 24 years without surgery. When blade atrial septotomy was the tricuspid regurgitation is due to the left ventricular performed during her cardiac catheterization in our hospital, volume overload, will this lessen or disappear when all she described her sensation as "the first time in my life that systemic venous return is rerouted directly to the pulmonary 1 could take a deep breath." Nevertheless . her left atrial artery and pulmonary blood flow is reduced? Although we hypertension was abolished only after surgical atrial septec- would intuitively answer these questions in the affirmative . tomy. Increased pulmonary blood flow necessitates a main the number of patients in this series who underwent atria- pulmonary artery band that should be placed at the same time pulmonary or cavopulmonary anastomosis is too smail to of the surgical septectomy . It is well known 136) that handing of provide reliable answers to these questions . At present, we the main pulmonary artery may be associated with progressive consider the patients who have a competent or mildly narrowing of the bulboventricular foramen. A less frequent regurgitant tricuspid valve and are free of atrial arrhythmias finding after banding or transection of the main pulmonarv favorable candidates for a fenestrated cavopulmonary anas- artery is the development of muscular stenosis within the tomosis . For the patients with significant tricuspid regurgi- subaortic infundibulum . It occurred in two cases in this series . tation. we recommend a bidirectional cavopulmonary shunt both with a straddling tricuspid valve and a large ventricular as the first stage of surgical palliative treatment . If the septa) defect . In Case 9, it was correctly diagnosed and tricuspid regurgitation improves significantly after this pro- surgically resealed. In Case 18. it was diagnosed as restriction cedure. a fenestrated cavopulmonary anastomosis can be of the bulboventricular foramen . which led to the placement of undertaken to complete the surgical treatment . a left ventricle to descending aorta conduit . The patient died Conclusions. The patients in this series provide clinical 20 h after operation (9). and anatomic data for the understanding and preoperative In the cases of coexisting pulmonary atresia (Case 7 . Fig . recognition of this unusual type of mitral valve atresia . We ID) or severe subpulmonary stenosis (Cases 19 and 25) . a believe that it is important to differentiate between mural systemic to pulmonary artery shunt becomes necessary very and tricuspid valve atresia in patients with AV valve atresia early in life, and a normal-sized or large left ventricle . This approach Fontan procedure. When more definitive palliative ther- allows the identification of subgroups of patients at risk for apy is contemplated (one of the modifications of the Fonton problems such as tricuspid regurgitation or coronary sinus procedure) (37.38) . the presence of significant tricuspid atresia. In addition, it provides data for better understanding regurgitation, atrial arrhythmias or pulmonary venous con- of the morphogenesis of such cases . nections to the superior vena cava may constitute important complicating factors. In this s eries . no patient with left-sided mitral atresia has successfully undergone any of the varia- We thank Emily Flynn-McIntosh far artwork . Melanie Fdedman for photog- raphy ned Shumn Heim f r,euitence in the preparation of the manuscript. tions of the Fontan procedure, although a classic Glenn

1576 SHINPO01 AL . IACC VII. 19 . N0 . 7 MURAL Al IIESIA WITH A LARGE LEFT VENTNICLF June 1052:1561-76

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