the surgical management of fallot'ssurgical assessment of the case. the points to establish...

POSTGRAD. MED. J. (I961), 37, 659

THE SURGICAL MANAGEMENT OFFALLOT'S TETRALOGY

D. N. Ross, B.Sc., M.B., F.R.C.S.Consultant Thoracic Surgeon, Guy's Hospital, London, S.E.x

FALLOT'S tetralogy is a condition of cyanotic con-genital heart disease associated with pulmonarystenosis and a ventricular septal defect. Theright ventricular hypertrophy and overridingaorta are probably a result of the altered hemo-dynamics.The essential features of the condition are

cyanosis, pulmonary stenosis and a ventricularseptal defect. Consequently, the so-called Trilogyof Fallot is excluded from consideration sincethese cases have no ventricular septal defect.Further, the term is misleading and should bedropped. Cases of ventricular septal defect withmild pulmonary stenosis and no cyanosis at restor on exertion are also excluded from considera-tion under the definition presented above.Finally, the term Pentalogy of Fallot provides nouseful information. This condition is betterknown as Fallot's tetralogy with an additionalatrial septal defect.

HIemodynamicsThe ventricular septal defect in Fallot's

tetralogy is invariably large so that there is afree communication between the right ventricle,the left ventricle, and the aorta. The obstructionto the outflow tract of the right ventricle is alsosevere with the result that when the right ventri-cular pressure rises in systole to systemic levels,the right ventricle discharges a large proportionof its contained desaturated blood into the leftventricle and aorta. Only a small proportion ofthe right ventricular ejection passes through thepulmonary stenosis to the lungs.The clinical picture resulting is one of cyanosis

as a result of unsaturated blood in the aorta.The haemodynamic effect is that of equal systolicpressures in the right ventricle, left ventricle andaorta (Fig. i). The diminished blood flow to thelungs means that an inadequate volume of bloodwill be oxygenated there. This inadequate bloodflow, and not the cyanosis, accounts for thepatient's disability. Recognition of this fact wasthe basis of the original Taussig-Blalock operationdesigned to increase the blood flow to the lungs.

FIG. I.-The relative volumes and direction of the rightventricular blood flow are shown together with theapproximate pressures in the ventricles and greatvessels.

AnatomyThe pulmonary stenosis may be purely valvar

in site with the valve orifice a few millimetres indiameter and often lying eccentrically with poorly-defined valve commissures.More commonly the obstruction is infundibular

in type consisting of a localized hypertrophy ofthe muscle and a thickening of the overlyingendocardium. This infundibular obstruction maylie in a high, medium or low position in relationto the pulmonary valve. Where it is low inposition there is a well-formed and thin-walledinfundibular chamber beyond it (Fig. 2). Thisis an example of an area of post-stenotic dilatation

copyright. on July 2, 2020 by guest. P

rotected byhttp://pm

j.bmj.com

/P

ostgrad Med J: first published as 10.1136/pgm

j.37.433.659 on 1 Novem

ber 1961. Dow

nloaded from

http://pmj.bmj.com/

POSTGRADUATE MEDICAL JOURNAL

VENTRICULARSEPTAL DEFECT

\~TRICUSPID&t VALVE

G 2FIG. 3.-Surgical anatomy of the ventricular septalFIG. 2.-Diagrammatic section through the right heart defect in Fallot showing relationships of bundle of

showing the thin-walled infundibular chamber His, aortic cusps, crista and septal cusp of tricuspidbeyond the obstruction and the ventricular septal valve.defect lying proximal.

occurring beyond an obstruction. Not infre-quently an infundibular and valvar stenosiscoexist.The ventricular septal defect in Fallot lies

beneath the supraventricular crest or proximalto the infundibular obstruction. It is thereforewithin the high-pressure zone of the right ven-tricle. In size it usually approximates the dia-meter of the aorta and it is often partly overlappedby the septal cusp of the tricuspid valve. Thebundle of His runs along the postero-inferiormargin of the defect (Fig. 3). Since the adventof open-heart surgery these aspects of the surgicalanatomy have acquired considerable importance.

Externally the ventricles are covered by numer-ous distended and tortuous coronary vessels wellin excess of the normal coronary vascular pattern(this is thought to be the result of anoxia).The pulmonary artery is usually small and of

low tension, while the aorta often has a diametertwo to three times as great and appears to arisepartly from the right ventricle. The relative sizeof the pulmonary artery and aorta reflect thedegree of shunting of right ventricular blood intothe aorta at the expense of the pulmonary arteryand is consequently a guide to the severity of thecondition.

Clinical FeaturesCyanosis. Children with Fallot's tetralogy are

cyanosed from birth or the cyanosis is noticedwithin the first few weeks. The degree of cyanosisvaries and is increased by crying and exertion.

In severe cases the child is subject to ' cyanoticattacks'. These are characterized by attacks ofdeep cyanosis and may be accompanied by loss of

consciousness or death. These attacks may beprecipitated by a ' spasm' or increased tonus ofthe infundibulum. This will have the effect ofdirecting all or most of the right ventricular bloodinto the aorta with the production of cerebralanoxia.

Alternatively, the cyanotic attacks may be pre-cipitated by diminution of the peripheral systemicresistance which will have the same effect ofdirecting blood preferentially into the aorta at theexpense of the pulmonary artery.

Squatting. Cases of Fallot's tetralogy adopt acharacteristic squatting attitude when they aretired and some children even sit in this positionin bed. The effect of the acute flexion at kneeand thigh may be to trap blood in the legs andso reduce the load of returning venous blood tothe heart. On the other hand, by increasing thesystemic vascular resistance (aided by splanchnic-bed compression by the thighs) the effect may beto divert more blood from the aorta to the lungs.

It is rare for a case of Fallot's tetralogy not togive a history of squatting, and where this isabsent one should be wary of the diagnosis.

Dyspnoea. All of these cases are dyspnceic to agreater or lesser degree, depending largely on theadequacy of the blood flow to the lungs.

Clubbing. Finger clubbing is a characteristicfeature of the condition; the degree of clubbingis usually proportional to the severity of thecyanosis. The toes also show clubbing and inseverely cyanotic cases the tip of the nose alsomay be clubbed.

Cardiovascular System. Examination reveals anormal pulse volume, distended veins and awarm periphery. The right ventricular activity

660 November I 96 I



j.bmj.com

/P


j.37.433.659 on 1 Novem

ber 1961. Dow

nloaded from

http://pmj.bmj.com/

ROSS: The Surgical Management of Fallot's Tetralogy

is moderately increased on palpation and a systolicthrill is often palpable in the second and thirdleft intercostal spaces. A pulmonary systolicmurmur is characteristically heard and is followedby the loud banging single sound of aortic valveclosure. Where the pulmonary stenosis is severethe thrill is absent and the systolic murmur maybe insignificant.

Special InvestigationsPolycythcemia. This again will vary with the

degree of cyanosis and is a good guide to theseverity of the condition pre-operatively. Post-operatively it offers an objective assessment of thedegree of improvement.

Electrocardiogram. This is not particularlycharacteristic but usually shows right ventricularhypertrophy of a moderate degree. Marked rightventricular hypertrophy is unusual and raises thepossibility of an intact ventricular septum.

Chest Radiograph. This is useful. The lungfields are typically oligaemic and the pulmonaryvasculature is often spidery.The heart contour may be sabot-shaped in

severe cases, but this picture is by no meansinvariable. The aorta is usually large and is right-sided in about 25% of cases.

Angiocardiography. This is important in thesurgical assessment of the case. The points toestablish are:

(a) Confirmation of the diagnosis.(b) Precise anatomy of the right ventricle out-

flow obstruction.(c) Size of the pulmonary artery branches and

the aorto/pulmonary artery ratio.(a) The contrast medium passes from right

atrium to right ventricle and from this chamberfills the pulmonary artery and aorta simultaneously.This confirms the presence of pulmonary stenosis,a ventricular septal defect, and a right-to-leftshunt.

(b) The anatomy of the infundibular and pul-monary valve obstructions can be identified.These features are seen most clearly in the lateralview (Fig. 4).

(c) The ratio of the size of the pulmonaryartery to the aorta can be measured. Where thediameter of the pulmonary artery is over 50% ofthat of the aorta, it suggests that this vessel willbe of adequate size to deal with the output ofblood from the right ventricle once the ventricularseptal defect has been closed. It is important toestimate the diameter of the pulmonary artery atthe position of the valve ring (Fig. 5), since thisis likely to be the narrowest area and cannoteasily be enlarged without causing pulmonaryvalve regurgitation.

Selective right ventricular angiography, achieved

a.

b).

FIG. 4, a and b.-Lateral angiocardiogram showing theanatomy of the right ventricular outflow in systoleand diastole. There is a valve stenosis present.

by means of a wide-bore catheter into the rightventricle, gives excellent anatomical detail.Asymmetry of the right and left main pulmonary

arteries and their peripheral distribution iscommon in Fallot's tetralogy.

Cardiac Catheterization. This examination isnot often necessary, but where there is difficultyin differentiating Fallot from other conditions it

November I 96 I 66Icopyright.

on July 2, 2020 by guest. Protected by

http://pmj.bm

j.com/

Postgrad M

ed J: first published as 10.1136/pgmj.37.433.659 on 1 N

ovember 1961. D

ownloaded from

http://pmj.bmj.com/


FIG. 5.-Angiocardiogram shows simultaneous filling ofpulmonary artery and aorta. The pulmonary arterydiameter suggests the case is suitable for a one-stagecorrective operation.

is valuable. This is particularly true if combinedwith selective angiocardiography.The catheter demonstrates the presence of a

pulmonary stenosis and also the fact that theright and left ventricular pressures are typicallyequal.

Differential DiagnosisOther cyanotic congenital heart disorders should

be excluded. Most important is the condition ofpulmonary stenosis with a closed ventricularseptum and reverse shunt through an atrial septaldefect. Since there is no ventricular septal defectto act as a safety valve, the clue to the diagnosisrests on the recognition of an obstructed rightventricle. Disability is likely to be severe, theright ventricle load is usually reflected in dis-tended neck veins with giant pulsations as aresult of increased atrial contractions. Theremay, in addition, be enlargement of the liver.Also the right ventricular action is powerful topalpation and there will be a long systolic murmurand quiet second heart sound. The electrocardio-graph will confirm the presence of right ven-tricular hypertrophy usually of a degree in excessof that found in Fallot's tetralogy. The radio-graphic contour of the heart is more globularthan in Fallot's tetralogy and there is usually adistinct post-stenotic dilatation of the pulmonaryartery.

Rarer conditions to be considered are trans-position of the great vessels, total anomalous

pulmonary venous drainage, and some cases oftruncus arteriosus. The diagnosis of these con-ditions rests oii clinical examination and con-firmation by special investigational techniques.

Surgical PrinciplesSurgical treatment aims at relieving the dis-

ability and at restoring the normal anatomywherever possible. The main disability stemsfrom the pulmonary stenosis. The ventricularseptal defect, however, represents an additionalhaemodynamic burden to the heart.There can be no doubt that the ideal treatment

is to remove the pulmonary stenosis and to closethe ventricular septal defect provided this can beachieved with an acceptable surgical risk. Wherethis total correction is not possible, relief of thepulmonary stenosis should be the primary sur-gical consideration.

Surgical ManagementThe Blalock-Taussig operation aims at over-

coming the pulmonary stenosis and poor pul-monary flow by circumventing the obstruction.The patient's disability is dramatically improvedand the relief afforded by the operation providesstriking confirmation of the view that the dis-ability in Fallot stems from the pulmonarystenosis. Its disadvantage lies in the fact that itdoes nothing to relieve the burden of the rightventricle and the presence of the anastomosisadds an additional problem when the case issubsequently dealt with by total correctivesurgery.On the other hand, the early results are excellent

and the increased blood flow to the lungs createsconditions for the development of the pulmonaryvasculature and left heart chambers. These latterfeatures may be important in ensuring the successof the subsequent corrective surgery.The Brock operation for Fallot's tetralogy

represents a direct but closed operation on thepulmonary stenosis. Where the obstruction is atvalve level, pulmonary valvotomy is performedand in cases of infundibular obstruction theinfundibular muscle is resected piecemeal withthe aid of Brock's infundibular punches. Theeffect of the Brock operation is to allow thedevelopment not only of the pulmonary vascularbed and left heart but also of the right ventricularoutflow tract under the influence of the increasedblood flow.

Both the Blalock and Brock operations leavethe patient with a ventricular septal defect and itis likely that these operations will in future berestricted to very young or high-risk cases as apreliminary or first-stage procedure. The closureof the ventricular septal defect and removal of the

662 November I 96 Icopyright.


http://pmj.bm

j.com/

Postgrad M


ovember 1961. D

ownloaded from

http://pmj.bmj.com/

ROSS: The Surgical Management of Fallot's Tetralogy

residual pulmonary stenosis can then be achievedat a subsequent operation.

Correction of the pulmonary stenosis andclosure of the ventricular septal defect as a one-stage procedure represents the ideal treatmentfor Fallot's tetralogy. It should be the mainaim of surgical management. In order to ensuresuccess, an efficient heart-lung apparatus andorganized team must be available. The machinemust be able to maintain the circulation for aminimum of 6o minutes and there must be skilledpost-operative nursing care.

In assessing a case for total correction, the sizeof the right ventricular outflow and pulmonaryartery is of importance since the whole cardiacoutput must be accommodated through thischannel after closure of the ventricular septaldefect. Where the diameter of the pulmonaryartery is grossly inadequate, many surgeons prefera preliminary Brock or Blalock operation.With regard to the technical aspect of the extra-

corporeal circulation, in general, the flow require-ments are proportionately higher in Fallot'stetralogy than in other cases of open-heart surgery.This results from the often considerable bronchialarterial ' leak' of blood from the systemic circuitto 'the lungs (Fig. 6). Consequently the volumeof oxygenated blood available for perfusion of thesystemic circuit may be inadequate for the physio-logical needs of the brain and other organs. Afurther disadvantage of this ' leak' is the embar-rassing volume of bronchial blood returning tothe operative field via the pulmonary veins andleft atrium. As much as one-quarter to one-thirdof the pump output may be dissipated in thismanner.The capacity of the pump-oxygenator must

therefore be able to meet these increased flowrequirements and this applies particularly toadult cases. In many centres, including Guy'sHospital, this difficulty is overcome by usingmoderate hypothermia to a temperature of about30°C. This ensures adequate reserves of oxy-genating capacity.

It is a further advantage to use hypothermicarrest of the heart's action in order to secure idealoperating conditions in a quiescent heart. Thisis most simply achieved by packing ice-salinecrystals around the heart as suggested by Hufnagel(Ross, I96I) (Fig. 7). Under these circumstancesthe increased bronchial return is also more easilydealt with than in the beating heart, and in factthe conditions approximate those available underprofound hypothermia and circulatory arrest.The right ventricle is opened through a reason-

ably short vertical incision over the outflow tract,taking care to avoid the large coronary arteries.Exceptionally, the main coronary blood supply

AORTICLEAK~

\-, X PERFUSION

FIG. 6.-This diagram indicates the bronchial 'leakof blood int9 the pulmonary veins and left atrium.

to the left ventricle may course across the line ofincision so that the operation may have to beabandoned where the incision cannot be plannedto avoid this vessel. Some surgeons have beenable to dissect the coronary out of the myo-cardium and retract it out of the line of theincision.The crista supraventricularis is a well-developed

muscular ridge in Fallot's tetralogy with thickenedoverlying endocardial 'icing'. In addition, thetrabecule carnew are usually seen as grosslyhypertrophied muscular bundles. There may bean associated valve stenosis and this should belooked for and dealt with before becoming pre-occupied with the infundibulum or ventricularseptal defect.The crista is resected generously by sharp dis-

section, taking care not to encroach upon theaortic valve ring and cusps which should beidentified adjacent to its deep surface. Attentionis then directed to the trabecule carnea. Theseare divided extensively rather than excised inorder to increase the mobility and diameter ofthe right ventricular outflow tract.The ventricular septal defect is then closed,

either by a direct suture technique (Kirklin, Ellis,McGoon, DuShane and Swan, I959) or with theaid of a plastic or pericardial prosthesis. In allcases the defect is large in relation to the size ofthe heart and has a fleshy muscular edge asopposed to the tougher and more tendinous edgein cases of isolated ventricular septal defect.Once the ventricular septal defect is closed it is

important to maintain decompression of the leftheart chambers and pulmonary bed, either by

November I 96 I 663



j.bmj.com

/P


j.37.433.659 on 1 Novem

ber 1961. Dow

nloaded from

http://pmj.bmj.com/


FIG. 7.-Dry operating conditions within the ice-arrested heart in Fallot's tetralogy.

venting these through a sucker in the pulmonaryartery or by means of a previously placed leftatrial sucker. The heart action can be restartedat this stage so that one can confirm the closureof the ventricular septal defect.

In a correctly-selected case it is now possibleto close the right ventriculotomy by direct sutureand this is the practice at Guy's Hospital. Wheretotal correction is attempted in cases with apoorly-developed right ventricular outflow tractor pulmonary artery, it is the custom to insertan elliptical gusset of plastic or pericardium atthis stage in order to increase the diameter of theright ventricular outflow. The gusset may evenbe carried through the pulmonary valve ring intothe pulmonary artery bifurcation in the mostsevere cases (Fig. 8), but this has the effect ofinflicting severe pulmonary regurgitation whichmay be a later source of disability.Once heart action is restored, pressures are

recorded in the right and left ventricles and pul-monary artery. Under favourable conditions theright ventricular pressure should be less than halfof that in the left ventricle and the pressuregradient between the right ventricle and pul-monary artery should be absent or small. A con-siderable residual gradient represents a seriouspost-operative load to the right ventricle whichhas the additional burden of an incision.

Post-operative bleeding following by-pass isoften a hazard, particularly in polycythamic cases,and no certain method of dealing with this com-plication has been offered. Blood loss is measuredcarefully and is replaced with fresh blood untilbleeding stops. This increased bleeding tendencyin severe Fallot's tetralogy appears to be one ofthe outstanding problems in the surgery of thiscondition.As in the closure of any ventricular septal

defect, heart block is a danger to be avoided at allcosts since permanently-established block has apoor immediate and late prognosis. Heart block,when it occurs, calls for the use of the electricalpace-maker and heart action must be carefullymonitored on the electrocardiograph.

Post-operatively cardiac output may be inade-quate during the first month to six weeks, and itis usual to keep the patient in hospital at least amonth post-operatively. This deficient cardiacoutput may be further evidence of the difficultiesof the left ventricle in dealing with its newwork load.

SummaryAt present the surgical management of Fallot's

tetralogy is reasonably standardized. Most casesare satisfactorily dealt with by a one-stage total

November I96 I664copyright.


http://pmj.bm

j.com/

Postgrad M


ovember 1961. D

ownloaded from

http://pmj.bmj.com/

November i96 RROSS: The Surgical Management of Fallot's Tetralogy 66q

corrective procedure. This should be achievedwith a 15 to 20% mortality.

In very young patients (usually under four)requiring surgical relief and in severely incapaci-tated cases at any age, a preliminary Blalock orBrock operation affords considerable clinical im-provement. A preliminary operation has theeffect of developing the right ventricular outflow,the pulmonary vascular bed and the left atriumand ventricle. These factors, together with thereduced polycyth;emia and bleeding tendency,result in an improvement of the clinical conditionand present a less formidable operative risk forsubsequent corrective surgery.

'4"'

p -SFIG. 8.-Diagram of a plastic gusset in the right ven-

tricular outflow tract.

REFERENCESKIRKLIN, J. W., ELLIS, F. H., MCGOON, D. C., DUSHANE, J. W., and SWAN, H. J. C. (I959): Surgical Treatment

for the Tetralogy of Fallot by Open Intracardiac Repair, J. thorac. Surg., 37, 22.Ross, D. N. (I96I): Ice Arrest of the Heart, Lancet, ii, 293.



j.bmj.com

/P


j.37.433.659 on 1 Novem

ber 1961. Dow

nloaded from

http://pmj.bmj.com/

the surgical management of fallot'ssurgical assessment of the case. the points to establish...

Documents