univentricular heart: an angiographic study

Univentricular Heart : An Angiographic Study

BENIGNO SOTO, MD, FACCALBERT D . PACIFICO, MD, FACCGERMANO Di SCIASCIO, MD

Birmingham, Alabama

From the Departments of Radiology, Pediatricsand Surgery, University of Alabama School ofMedicine, Birmingham, Alabama . Manuscript re-ceived June 15, 1981 ; revised manuscript re-ceived August 19, 1981, accepted September 4,1981 .

Address for reprints : Benigno Soto, MD, De-partment of Diagnostic Radiology, University ofAlabama School of Medicine, 619 South 19thStreet, Birmingham, Alabama 35233.

Axial angiograms of 54 patients with a univentricular heart were reviewedto determine the anatomic details demonstrated by this technique . Themain ventricular chamber was of left ventricular morphology in 36, rightventricular morphology In 13 and Indeterminate in 5 patients. Forty-threepatients had a rudimentary ventricular chamber that was supporting agreat artery in 35 patients. Eighteen patients had separate atrioventricular(A-V) valves. In four of them, one A-V valve was overriding the trabecularseptum, but predominantly committed to the main ventricular chamber .Eleven patients had a single right and 13 a single left A-V valve; a commonA-V valve was present In 12 .

The techniques used provided good demonstration of the morphologyof the ventricular mass, particularly the position and orientation of aseptum when present . They also delineated the morphology of the A-Vvalve or valves and their precise ventricular connection . Ventriculoarterialconnections and relations were readily determined . It is concluded thatthese methods are superior to isolated frontal and lateral views and pro-vide thorough demonstration of the intracardiac anatomy of patients witha univentricular heart .

The group of congenital heart malformations unified by the connectionof the atrial chambers to only one ventricular chamber (univentricularheart) has been extensively studied by anatomists.'-5 The angiographicanatomy in this group of hearts, initially described by Hallerman et al . 6in 1966, was later amplified by others 7-9 using frontal and lateral views .In 1977, Bargeron and associates'" ," described the use of axial views toenhance the angiographic definition of congenital heart defects . In thisstudy we describe the angiographic features of the univentricular heart.as observed from axial angiocardiograms .

Definition of TermsMorphology of main ventricular chamber : In all the hearts re-

ported on, the atrial chambers were connected to only one ventricularchamber, because of either the presence of double inlet atrioventricular(AN) connection or the absence of one A-V connection . Following thelead of Anderson et al . 4 . 12,1 s we have termed the hearts univentricular .This distinguishes them from the majority of congenitally malformedhearts in which each atrium is connected to its own ventricular chamber,either through a patent or an imperforate A-V valve . The latter heartsare biventricular. In the univentricular heart, the chamber connectedto the atria (main ventricular chamber) may be of a left ventricular, rightventricular or indeterminate type depending on the pattern of its tra-becular component. In the majority of univentricular hearts as thusdefined, a second and rudimentary chamber is present . Such a rudi-mentary ventricular chamber has a right ventricular trabecular patternwhen found in a heart whose main chamber is of the left ventricular typeand a left ventricular trabecular pattern when found in a heart whosemain chamber is of the right ventricular type . A heart with an indeter-minate trabecular pattern does not possess a rudimentary ventricularchamber. A rudimentary ventricular chamber of either a right or a leftventricular type is termed outlet chamber when it supports one or more

March 1982 The American Journal of CARDIOLOGY Volume 49

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ANGIOGRAPHY IN UNIVENTRICULAR HEART-SOTO ET AL .

great artery or a trabecular pouch when it has neitherA-V nor ventriculo-arterial connections .A-V connections : As indicated, one of three types

of A-V connections can produce a univentricular heart .First, both atrial chambers may be connected with themain ventricular chamber (doublet inlet ventricle) . Thismay be effected through two distinct, separate valvesor through a common valve . Overriding of one valve orthe common valve is present in the setting of a univen-tricular heart when the lesser part of the valve orificeis committed to the rudimentary chamber . 14 If themajority of the valve is committed to this rudimentarychamber, then the heart is considered biventricular .Straddling of an A-V valve may or may not be associatedwith overriding and is present when the subvalve tensorapparatus in part originates from the rudimentarychamber. The other two types of A-V connection existwhen either the right or the left A-V connection is ab-sent. Then a single valve connects the contralateralatrium to the main ventricular chamber. This is incontrast to a common valve, which is usually large andconnects both the left and the right atria or the left andthe right portions of a common atrium with the mainventricular chamber. This valve is similar to thatpresent in a complete A-V canal defect. The terms singleand common A-V valves are not used interchangeably .Although a single or a common valve usually enters themain chamber completely, either may override thetrabecular septum to become partially connected withthe rudimentary chamber .

Ventriculoarterial connections: The great arteriesmay arise from the heart in four ways : (1) a concordantvetriculo-arterial connection exists when the aortaoriginates from the left ventricular chamber and thepulmonary trunk from the right ventricular chamber ;(2) discordant connections are present when the aortaoriginates from the right ventricular chamber and the

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TABLE I

Ventricular Morphology in 54 Univentricular Hearts

pulmonary trunk from the left ventricular chamber ; (3)double outlet exists when both great arteries originatefrom the same ventricular chamber, whether it is a mainor a rudimentary chamber ; and (4) single outlet ispresent when a single vessel (aorta, pulmonary arteryor truncus arteriosus) arises from the heart . 15

A univentricular heart may exist in patients with situssolitus, situs inversus or with atrial isomerism, and thecardiac base-apex axis may be directed to the left orright .

MethodsStudy patients: The angiographic studies in 54 patients

fulfilling the criteria for univentricular heart were selected forthis analysis . Some of these patients were previously de-scribed.t 6 There were 34 male and 20 female patients whoranged in age from 1 day to 18 .5 years . Each patient under-went cardiac catheterization and angiographic studies usingaxial projections . The diagnosis was confirmed at surgery in10 patients and in 2 at necropsy as well .Angiography : Angiograms were filmed with the patient

anesthetized using 35 mm biplane tine at 60 frames/s. Eachventriculogram was filmed in the four chamber, long axial andelongated right anterior oblique views)°" 11 The four chamberview is defined as a 45°left anterior oblique view with 30° ofcraniocaudal angulation added . The long axial view combines

FIGURE 1 . Univentricular heart of right ventricular (RV)type .Selective injection into the main ventricular chamber in fourchamber (A) and elongated right anterior oblique (B) views .The main ventricular chamber (RV) shows coarse trabecu-lation similar to that of the normal right ventricle . A smallaccessory chamber or trabecular pouch (TP) is locatedposteriorly . The trabecular septum is depicted in profile (B)delineating the trabecular septal defect (arrow) . The aorta(AO) and pulmonary artery (PA) originate from the mainventricular chamber in a side by side relation .

Main Chamber n Accessory Chamber nLeft ventricular type 36 Outlet chamber 35

Trabecular pouch 0None 1

Right ventricular type 13 Outlet chamber 0Trabecular pouch 8None 5

Indeterminate 5 None

FIGURE 2 . Univentricular heart of left ventricular (LV) type . Selectiveopacification of the main chamber in the `four chamber" view : A, di-astolic frame ; B, systolic frame. The main ventricular chamber (LV) hasfine trabeculations, both at the free wall and at the septal aspect, whichdoes not change during systole . This appearance is very similar to thatof the normal left ventricle . There is an outlet chamber (OC) locatedanteriorly which supports the aorta . The aorta (AO) is anterior to thepulmonary artery (PA) and there are discordant ventriculoarterial con-nections . The left (lav) and right (rav) A-V valves are well demon-strated .

60° of left anterior oblique angulation with 30° of craniocaudalangulation. The elongated right anterior oblique view is a 30 °right anterior oblique view with 30° of craniocaudal angula-tion .

Chambers were defined as right ventricular, left ventricularor indeterminate depending on their trabecular pattern (Fig .1 to 3), independent of their connections or relations as de-scribed by Tynan et a] . I"

FIGURE 3. Univentricular heart of in-determinate type . A, selective angio-gram into the main ventricular chamberin "four chamber" view . B, anatomicspecimen from the same patient. Thetrabeculation of the main ventricularchamber (MV) in A, does not resemblethe normal right or left ventricularconfiguration . In some areas the myo-cardium resembles a right ventricle, butin others a left ventricle . This is con-firmed in the anatomic specimen (B) .No accessory chamber was identifiedin this heart by either the angiographicor anatomical study . RA = right atrium ;other abbreviations as before .

ANGIOGRAPHY IN UNIVENTRICULAR HEART--SOTO ET AL .

FIGURE 4 . Univentricular heart of right ventricular type with a largetrabecular pouch . Selective injection into the trabecular pouch in thelong axial view . A, early diastole; B, late diastole . The main ventricularchamber (RV) is poorly opacihed because of dilution with nonopacitiedblood coming from the atria . The trabecular pouch (TP) is well pacifiedand has a smooth outline, similar to that of the normal left ventricle . Itis located posteriorly . PA = pulmonary artery . Reproduced from Sotoet al . 16 by permission of the American Heart Association, Inc .

Results

Situs solitus of the atria was present in 42 patientsand situs inversus in 2 . Ten patients had atrial isomer-ism, five of right and five of left isomeric type . Thecardiac apex was directed to the left in 52 patients andto the right in 2 patients .Ventricular morphology (Table I) : The main

ventricular chamber was of a right ventricular config-uration in 13 patients (Fig . 1), of a left ventricular con-

March 1982 The American Journal of CARDIOLOGY Volume 49 789


figuration in 36 (Fig. 2) and of indeterminate patternin 5 (Fig . 3) . Of the 13 patients with a right ventricularmain chamber, 8 had a left ventricular rudimentarychamber. All were trabecular pouches that were locatedposteriorly and inferiorly (Fig . 4) . Two of the trabecularpouches were large and the remaining six were small .They were connected to the main ventricular chamberby a single septal defect in six patients and by multipledefects in two . In the remaining five patients with amain chamber of right ventricular type a rudimentarychamber was not identified.

In 35 of the 36 patients with a univentricular heartof the left ventricular type there was a rudimentarychamber of right ventricular type (Fig . 5) . In the re-maining patient, no rudimentary chamber was identi-fied. The rudimentary chamber was positioned directlyanteriorly in 6 of the 35 patients, anteriorly and to theright in 17 and anteriorly and to the left in 12 . The outletchamber was considered large in 30 patients and smallin 5. When large, an extensive trabecular segment wasseen oriented toward the apex of the heart which con-tained well defined trabeculations similar to those of theright ventricle . When the outlet chamber was small, itwas of smooth contour and without well defined tra-beculations. It still extended towards the ventricularapex and was separated from the main chamber by thetrabecular septum. The outlet foramen connecting theoutlet chamber to the main ventricular chamber waslarge in 28 patients, small in 2 and multiple in 3 pa-tients .

A-V connections (Table II) : Among the 13 patientswith univentricular heart of the right ventricular type,10 had double inlet connection and 3 had absent leftA-V connection. The double inlet occurred throughseparate valves in six patients, the right A-V valveoverriding the septum, partially connected with thetrabecular pouch, in one of these. Four patients had acommon valve guarding the double inlet connection(Fig. 6). A single right A-V valve connecting the rightatrium to the main chamber was found in three cases .

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FIGURE 5 . Univentricular heart of left ventricular typewith an outlet chamber located anteriorly . The "fourchamber" projection was used after selective injec-tion into the main chamber (A) and outlet chamber (B).The main ventricular chamber (LV) has the morpho-logic features of the normal left ventricle . The outletchamber (OCH) completely supports the aorta (AO)and is connected to the main chamber by two outletforamens. PA = pulmonary artery .

Among the 36 univentricular hearts of left ventric-ular type, double inlet was present in 16, absent leftconnection in 7 and absent right connection in 13. Of the16 hearts with double inlet, 10 had two A-V valves and6 had a common valve . Overriding of a single and rightA-V valve was present in two patients (Fig. 7) andoverriding of a single and left A-V valve in two others .All hearts with absent right connection had the singleleft valve exclusively connected to the main chamber .However, among the seven hearts with absent leftconnection, the single right valve was exclusively con-nected to the main chamber in six but overrode thetrabecular septum in one .

In the five patients with an indeterminate, soleventricular chamber, there was double inlet in fourpatients and absent left A-V connection in one patient .The double inlet occurred through two valves in twopatients (Fig . 8) and through a common valve in theother two (Fig . 9) .

Of 36 patients with situs solitus of the atria, 22 haddouble inlet connection, 7 had absence of the left A-Vvalve and 13 had no right A-V valve. In all patients withsitus inversus the A-V connection was of the double inlet

TABLE II

Atrioventricular (A-V) Connections in 54 UniventricularHearts

Main ChamberMorphology

A-V Valve Left Right Indeterminate

Separate 10 6 2(Overriding right) (2) (1) (0)(Overriding left) (2) (0) (0)

Single right 7 3 1(Overriding) (1) (0) (0)

Single left 13 0 0Common 6 4 2

FIGURE 6 . Univentricular heart of right ventricular type witha trabecular pouch and a common A-V valve in the "fourchamber" view . The main ventricular chamber (RV) hascoarse trabeculations similar to those of the right ventricle .The trabecular pouch (TP) has a smooth contour similar tothat of the normal left ventricle . The major part of the com-mon A-V valve (arrows) connects the atria to the main ven-tricular chamber but a small portion of it overrides the tra-becular pouch. The aorta (AO) and pulmonary artery (PA)originate from the main ventricular chamber . The trabecular(S) and infundibular (IS) septa are well profiled .

type. In the five patients with left atrial isomerism andin four with right atrial isomerism, the A-V connectionwas of the double inlet type through a common A-Vvalve. One patient with left isomerism had two sepa-rated A-V valves .

Ventriculoarterial connections (Table III) : Inthe 36 patients with a univentricular heart of the leftventricular type, the ventriculo-arterial connectionswere concordant in 14 and discordant (Fig. 10) in 16patients; in 1 there was a double outlet from the rudi-mentary right ventricular chamber (Fig . 11) and in theremaining 5 there was a single outlet aorta from rudi-mentary chambers with pulmonary atresia . All 13 pa-


tients with a univentricular heart of the right ventriculartype had a double outlet from the main ventricularchamber and all 5 with an indeterminate heart haddouble outlet from the sole ventricular chamber .

CommentsDiagnostic advantage of axial techniques : This

study demonstrates the usefulness of axial techniquesfor angiographic definition of the cardiac anatomicdetails of patients who have only one ventricularchamber connected to the atria (univentricular heart) .Although ventricular morphology can be similarly de-fined by frontal and lateral projections . axial views that

FIGURE 7 . Univentricular heart of left ventricular type with atresia of the left A-V valve and overriding of the right A-V valve . Angiograms obtainedin "four chamber" view . A, selective opacification of the left atrium ; B, selective opacification of the main ventricular chamber C, selective opacificationof the right-sided outlet chamber . The main ventricular chamber (LV), is of the left ventricular type . A large right A-V valve (rv) connects the rightatrium to the main ventricle and partially overrides the trabecular septum . The opacification of the left atrium (LA), shows atresia of the left A-Vvalve (arrowheads in A) and a large interatrial communication . AO = aorta ; OC = outlet chamber ; PA = pulmonary artery ; RA = right atrium .


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FIGURE 8 . Univentricular heart of indeterminate type with double outletmain chamber in "four chamber" view . Selective opacitication of theventricular chamber (MC) in diastole showing the rings of the right (rav)and left (lav) A-V valves, which are related to the pulmonary valve . Theinfundibular septum (IS) is seen in profile, separating the subaortic fromthe subpulmonary outlets. No accessory chamber was identified in thisheart . AO = aorta ; PA = pulmonary artery .

profile the trabecular septum provide more precise in-formation regarding trabecular pattern and size of therudimentary ventricular chamber and the outlet fora-men or trabecular septal defect . In addition, the num-ber, type, size and function of the atrioventricular (A-V)valves are well demonstrated and in most cases therelation of the A-V valve to the trabecular septumpermits diagnosis of an overriding valve . Straddling isnot often accurately diagnosed, although occasionally

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TABLE III

Ventriculoarterial Connection in 54 Univentricular Hearts

the origin of some chordae can be detected . Two di-mensional echocardiography is probably more usefulin this regard . The ventriculoarterial connection can beuniformly defined by these views .Surgical implications: Complete angiographic

definition of the main chamber and of the outletchamber is important if intracardiac surgery is con-templated, especially when a septation procedure isbeing considered or when a pressure gradient existsbetween the main and outlet chambers . The morpho-logic features of the main chamber and the relation ofthe outlet chamber and its foramen to each A-V valvebecome of major importance during surgical septation .A pressure gradient between the main chamber and thegreat vessel supported by the outlet chamber may existsingularly or at multiple levels at the outlet foramen,within the outlet chamber itself or the semilunar valveor its anulus . Sometimes clear definition of thesestructures is provided by injection into the mainchamber alone, but in some instances an additionalselective injection into the outlet chamber is helpful .

Identification of the rudimentary ventricularchamber: Generally, a rudimentary ventricularchamber of complimentary type was found when thechamber connected to the atrium was of either left orright ventricular configuration. This was not always thecase. In one heart of the left ventricular type and in five

FIGURE 9. Univentricular heart of indeterminate type witha common A-V valve in "four chamber" view. Selective in-jection of the main chamber in diastole (A) and systole (B) .A common A-V valve (arrowheads) connects the atria to themain ventricular chamber (MC). The single anulus of thisvalve is well defined by the accumulation of contrast mediumbeneath the leaflet attachments . AO = aorta : PA = pulmo-nary artery .

Type n

Concordant 14Discordant 16Double outlet 19

(Right ventricle) (13)(Left ventricle) (0)(Indeterminate) (5)(Outlet chamber) (1)

Pulmonary atresia 5

FIGURE 10 . Univentricular heart of left ventricular type withdiscordant ventriculo-arterial connections . Selective injectioninto the main (A) and outlet (B) chambers in the "fourchamber" view . The patient has situs solitus and dextro-cardia . The main ventricular chamber (LV) has the morpho-logic features of the left ventricle and receives the right (rav)and left (lav) A-V valves . The outlet chamber (OC) is seenbetter in (B), and supports the aorta (AO), which is locatedto the left . The pulmonary artery (PA) arises from the mainchamber and there is a severe stenosis in its subvalvearea .

hearts of the right ventricular type, a rudimentarychamber was not seen although diligently searched for .This could indicate either that there was indeed nosecond rudimentary chamber or that the first rudi-mentary chamber was so small as to be impossible toidentify using angiographic techniques . Only autopsyexamination including histologic studies can resolve thisquestion. Such studies'7 have shown that in a univen-tricular heart of the right ventricular type, the rudi-mentary left ventricular chamber can be exceedinglysmall and "missed" by gross autopsy techniques. Incontrast, the present study has shown that chamberslacking an A-V connection can also be unusually large .This finding emphasizes the need to describe both theanatomy of a ventricular chamber (that is, components)and its size .Identifying the A-V connections : The major

problem in defining hearts as univentricular arises whenan atrium is connected to both chambers in the ven-tricular mass. When the atria are exclusively connectedto one chamber, there is no problem . Then the second

FIGURE 11 . Univentricular heart of left ventricular type with double outletfrom the outlet chamber. Selective left ventriculogram in the long axial viewin diastole (A) and systole (B). The main ventricular chamber (LV) receivesthe left (lav) and the right (rav) A-V valves. This chamber is connected tothe anterior outlet chamber (OC) through the outlet foramen (septal defect)(SD) . Both the aorta (AO) and pulmonary artery (PA) arise from the outletchamber and the infundibular septum separates the subaortic from sub-pulmonary outflow tracts.


chamber is unequivocally rudimentary, although onoccasion it may be large, because of its total lack of anA-V connection. The studies described here show clearlythat this morphologic feature can be defined angiocar-diographically, and that such chambers can be shownto be rudimentary (lacking an inlet component) solelyby examining their angiocardiographic features . How-ever, problems do arise when an atrium is connected toboth chambers (overriding valves) . In this circumstance,and in this circumstance alone, the decision as towhether the heart should be considered univentricularis made on a judgment of the degree of commitment ofthe overriding A-V connection. It is in this circumstancethat axial views during angiocardiography are invalu-able .

AcknowledgmentW e thank Lionel M. Bergeron, Jr., MD for his helpful advice

and permission to photograph his angiocardiograms . We alsoappreciate the useful criticisms of Robert H . Anderson,MD.

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univentricular heart: an angiographic study

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