THE DIAGNOSIS AND TREATMENT OF COMPLETEANOMALOUS PULMONARY VENOUS DRAINAGE

BY

W. T. MUSTARD*From the Hospital for Sick Children, Toronto

Anomalous pulmonary venous drainage, expressedin the simplest of terms, means that pulmonaryveins fail to enter the left auricle. If one or twopulmonary veins fail to enter the left side of the heartthere may be no outward signs of cardiac disabilityand the patient leads a relatively normal life. Evenif one half of the oxygenated blood enters directly orby venous channels into the right auricle there maybe very few symptoms. However, more than half thevenous drainage from the lungs entering the rightside of the heart will constitute some disability, andtotal anomalous pulmonary venous drainage inwhich no pulmonary veins enter the left atrium isusually accompanied by a poor prognosis and deathin infancy. In order to survive there must be anintracardiac communication, usually intra-atrial, inthe form of a patent foramen ovale or intra-auricularseptal defect. The intracardiac shunt is obviouslyfrom right to left, and survival beyond infancy willdepend largely on the size of this communicationbetween the two auricles.An embryological study of this lesion is interesting

since it concerns not only the rudimentary systemicvenous return but also the venous return of thelungs. In early developmental stages, the lungs,which are considered to develop by division of theforegut, are drained by umbilico-vitelline veinswhich in turn enter the systemic pre-cardinal andpost-cardinal veins. The post-cardinal veins unite toform the inferior vena cava and the pre-cardinalveins the right superior vena cava. While thesesystemic channels are becoming delineated into thenormal situation, a channel from the sinal atrialregion of the primitive heart tube outpouches tobecome the left atrium which grows towards thelungs and develops a communication whicheventually forms the normal pulmonary venousdrainage.

If one were to postulate that, at the stage at whichthe pre-cardinal veins are busy disappearing and the

* Alex Simpson Smith Memorial Lecture, 1956, given at TheHospital for Sick Children, Great Ormond Street, London.

outgrowth of the left atrium is equally busy tryingto reach the lungs, growth in these venous channelswere to stop, then one is left with the left atriumtrying in vain to reach the lungs and the lungs quitehappy with their drainage into the systemic systemof veins. If such a situation persisted it would resultin total anomalous pulmonary venous drainage inwhich the pulmonary veins entered the embryologicalcardinal venous system. Partial interruption wouldresult in one or more veins making an anastomosiswith the outpouching of the left atrium. The venouschannels connecting the lungs to the systemic venoussystem would become elongated and develop intorecognizable channels. Due to the disappearance ofcertain parts of the systemic venous channels therepersists a common vein which drains the pulmonaryveins and enters the right auricle by way of estab-lished systemic venous channels (Fig. 1).

Left .s.u.perio...-.i ,ena

.R.ight... ..

*pul*iarves:- eins'

-Lf.tiionarein:.

FIG. 1.-Schematic illustration of the pulmonary veins entering thepersistent left superior vena cava rather than the left auricle.

Fortunately, Snellen and Albers (1952), closelyfollowed by Gardner and Oram (1953), suspectedthat this condition could be diagnosed clinically ifthe presence of a common venous channel wasrecognized both by clinical investigation and byradiography. Brown (1950) and Whitaker (1954)have contributed in drawing attention to this

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ARCHIVES OF DISEASE IN CHILDHOOD

anomaly. Darling and Rothney (1956) have definedaccurately the clinical pathology. If complicatedcardiac anomalies can be excluded, an isolated formof anomalous pulmonary venous drainage, total innature, which can be classified either supracardiac,cardiac, infracardiac and mixed, can be recognized.

Fortunately for the surgeon, almost 50% of casesof total anomalous pulmonary venous drainage aresupracardiac and drain into a common venouschannel, which, on a clinical basis, can be describedas a persistent left superior vena cava or aprecardinal vein. Unfortunately, to be a true pre-cardinal vein, it should drain into the sinus venosus,but this is not necessarily true. Drainage into thesinus venosus or coronary sinus is at a cardiac leveland drainage into the ductus venosus and the portalsystem is intracardiac. The mixed type, which isexceedingly rare, can be a combination of theseforms.As this anomaly is recognized by pathologists,

the incidence may increase, since at necropsy, if theheart is removed from its pericardial sac and it liftsfree, an anomalous pulmonary venous drainage iscertainly there because of the loss of the tetheringeffect of the pulmonary veins entering the leftatrium. At necropsy, both right ventricle and rightauricle are enlarged, the extreme dilatation of theright ventricle masking, to some effect, hypertrophy.The intra-atrial communication is usually a patent

foramen ovale (75% of cases) but may be a largesecondary intra-auricular septal defect. The ductusarteriosus is patent in approximately 25% ofpatients. The pulmonary artery is larger than normal,usually one and a half times the diameter of theaorta. The tricuspid valve ring is larger than theright mitral valve ring and the diameter of thecommon pulmonary vein, which drains into theright auricle, may be twice the diameter of the waistof the left auricle-of some consideration when oneentertains the possibility of surgical approach.One-third of cases show intimal thickening andevidence of pulmonary hypertension. This anomalyprobably represents, to the best of our knowledge,2% of all cardiac malformations in infancy andchildhood.The haemodynamics of this condition are interest-

ing. Pulmonary venous blood of high oxygensaturation enters the right auricle through thecommon venous channel and mixes with systemicblood of lower saturation, and a variable proportionof both streams passes from the right auriclethrough a defect in the auricular septum (either apatent foramen ovale or an auricular septal defect)to the left heart and aorta. Also a proportion passesthrough the tricuspid valve to the right ventricle and

out through the pulmonary artery. For this reasonthe oxygen saturation of the blood in the heart andthe systemic circulation is approximately the same.When one considers the clinical features of this

isolated form of total anomalous pulmonary venousdrainage, there are certain signs or symptoms duringthe first two years of life. The first symptom isusually one of tachypnoea. Cyanosis is usuallyabsent in the next few weeks or a month. Theinfant fails to gain weight satisfactorily and becomesintermittently cyanosed. Distinct cyanosis, grosstachypnoea or failure demands further investigationin the older infant. A typical case is dystrophic anddyspnoeic. Equivocal cyanosis produces a muddydiscoloration. Clubbing is rare. The liver is usuallyenlarged and the praecordium bulging. One-thirdof cases show no murmurs. A systolic murmuralong the sternal border may be present andoccasionally a soft continuous venous hum, due toturbulence in the common venous channel, can be Kdiscovered.

Radiographically, increased lung vascularity,progressive cardiac enlargement, a left-sided aortaand a 'snowman' appearance, due to the persistenceof a left superior vena cava, develop around4 months of age (Fig. 2). This appearance isdescribed in the English literature as a 'cottage loaf'appearance. The difference in nomenclature ispossibly climatic in origin. Most Englishmen havenever made a snowman and most Canadians thinka cottage loaf is a summer vacation.

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FIG. 2.-'Cottage loaf' appearance due to persistent superior venacava.

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COMPLETE ANOMALOUS PULMONARY VENOUS DRAINAGE

Electrocardiographic tracings show a uniformpattern: right axis deviation, high p waves, rightventricular hypertrophy and q wave in the rightpraecordial lead.

Cardiac catheterization demonstrates oxygensaturation high in the right auricle and in thesuperior vena cava. An increase in right auricularpressure, double the average mean pressure, isusually present, and pressure is increased in thepulmonary artery to, or nearly to, systemic level.Occasionally, exploration by catheter may revealanomalous pulmonary venous drainage entering theleft innominate vein (Fig. 3).

this common venous channel with the pulmonaryveins entering it, and the waist of the left atrium isbrought up (Fig. 4). We feel that it is unwise to

FIG. 4.-Appearance of this anomaly as seen at operation with aposterior-lateral incision in left chest.

FIG. 3.-Oxygen saturation in total anomalous pulmonaryvenous drainage.

Indication dilution techniques, after injection ofEvans blue into a peripheral vein, may demonstratea short appearance time with a double tip character-istic of right-to-left shunt.With the physician cognizant of the condition and

the diagnosis confirmed, exploration by thoracotomyis indicated. In our early cases, an anterior approachwas used, but more recently we have favoured alateral approach, somewhat posterior in the fourthinterspace on the left side.Our first three cases in 1952 were operated on

at normothermic temperatures. One case wasoperated on at the extracorporeal circuit using apump and biological oxygenator. Since that timewe have used hypothermia, cooling down to 310 C.and allowing a drift to 280 C. Since these areinfants they are cooled in a water bath; over theage of 3 years we use a cooling blanket.

It has been our experience that a common venouschannel is immediately seen and dissection is carrieddown both extra- and intrapericardially to expose

anastomose the atrial appendage to the commonvenous channel because of the size of the waist ofthe left auricle, which in most cases is only one-halfthe diameter of the common venous channel. Inorder to obtain a large anastomosis, the waist of theleft atrial appendage is divided longitudinally,which, when it becomes open after anastomosis,will be roughly one and one-half times its normalsize. The occlusion of the left atrium in its entirety,including its appendage, and of the venous returnfrom the lungs required, in our opinion, the addedprotection of hypothermia. Side-to-side anasto-mosis is carried out, and the surgeon is alwaystempted and has indeed, on many occasions, tiedoff the communication to the right auricle via thepersistent left superior vena cava (Fig. 5).

t_~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:: .... ...FIG. 5.-Anastomosis between the common venous

pool and the waist of the auricle.

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4 ARCHIVES OF DISEASE IN CHILDHOOD

Of our first case surviving operation, in 1954, wehave no follow-up study as the patient died twomonths post-operatively with an ear infection. Inthis patient the superior vena cava had been ligated.On discharge from hospital the patient was inexcellent condition. Our subsequent experiencewith cardiac irregularity and death after ligation ofthe superior vena cava led us to believe that thepersistent superior vena cava should not be ligated,and in our seventh case in 1954 this was not doneand the baby, operated upon at 3 months, is thrivingand well two years post-operatively. This experienceled us, in our eighth case, to leave the vena cavaopen and re-catheterization of this patient fivemonths post-operatively showed no evidence ofright-to-left shunt. The oxygen saturation in boththe superior and inferior vena cava was normal(superior vena cava 63 %; inferior vena cava 75 %).A large volume left-to-right shunt was presentbetween the auricles and indicated the presence ofan auricular septal defect. A gain of 10 lb. inweight, lack of symptoms and reduction in rightheart strain in the E.C.G. indicated that the newhaemodynamic situation of an isolated septal defectwas much better tolerated than the combination oftotal anomalous pulmonary venous drainage andauricular septal defect.

In our next three cases, we became foolishly braveand ligated the superior vena cava. These patientsdied and demonstrated a relatively small intra-atrialseptal defect and a patent foramen ovale. We thenfelt that it would be unwise to tie the superior venacava in any case because of the size of the left heartand its inability to withstand the additional load ofall the pulmonary venous return to it.

In our last case in February of this year we werefortunate in that it was a mixed lesion in which theleft pulmonary vein entered the persistent left

superior vena cava and all other veins entered thecoronary sinus. We anastomosed the auricularappendage to the persistent left superior vena cavaand then ligated it. The waist of the left auricle wasthen anastomosed to the coronary sinus. This childis alive and well and has not been re-catheterized.

In conclusion I should like to comment upon thisinteresting condition of total anomalous pulmonaryvenous drainage and its possible surgical correction.With experience of 12 patients operated upon, fourof whom survived operation, one dying two monthspost-operatively, and three alive and well, we feeljustified in making certain recommendations.

First, the diagnosis, since total anomalouspulmonary venous drainage represents 2% of cardiacanomalies, should be made more frequently bothon the clinical and radiological findings. Secondly,surgery should be undertaken in all cases and ananastomosis between the common venous pool andthe waist of the left auricle should be attempted.This should be done under the protection of hypo-thermia or an extracorporeal circulation. Finally,the common venous drainage to the right auricleshould not be ligated at the time of operationbecause of the additional load thrust on the leftheart and the subsequent failure. Whether thiscommon venous channel to the left auricle shouldbe ligated subsequently or not is a decision I wouldleave to wiser surgeons.

I am indebted to Dr. John Keith and Dr. RichardRowe, cardiologists at the Hospital for Sick Children,Toronto, for their help in the preparation of this paperand their unfailing interest and enthusiasm.

REFERENCES

Brown, W. E. (1950). J. Okla. med. Ass., 43, 98.Darling and Rothney (1956). Personal communication.Gardner, F. and Oram, S. (1953). Brit. Heart J., 15, 305.Snellen, H. A. and Albers, F. H. (1952). Circulation (N. Y.), 6, 801.Whitaker, W. (1954). Brit. Heart J., 16, 177.

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