UPDATEThe Fontan Procedure: What HaveWe Learned and Accomplished?Douglas D. Mair, MD, Mayo Clinic and Mayo Foundation, Rochester, Minnesota

In 1969 Fontan performed his first pioneering operation ona patient with tricuspid atresia designed to completely sep-arate the systemic and pulmonary circulations and therebyeliminate the systemic arterial hypoxemia and left ventricu-lar volume overload which were the hallmarks of this con-dition (1). Although this procedure, which subsequentlybore his name, was not truly corrective because of its inabil-ity to establish a two-ventricle circulation, it was potentiallya higher grade of palliation than what had been previouslyprovided through various shunting operations which didnot completely separate the two circulations and whichoften added substantially to the volume load on the singlefunctional left ventricle. It was recognized at the onset,however, that the elevated systemic venous pressures inevi-tably present in the post-Fontan patient, necessary to propelthe blood through the lungs in the absence of a “boosterpump” on the right side of the circulation, might lead to latecomplications in surgical survivors and that functional lim-itations would likely still exist in these patients, particularlyin physical activities requiring a substantial increase in car-diac output.

More than 25 years have past since Fontan’s initial proce-dure, it has undergone many technical modifications, asurgical evolution which still continues, and its use has beenexpanded and applied to many anatomic types of functionalsingle ventricle in addition to tricuspid atresia. Several thou-sands of patients around the world have had the procedureand many surgical survivors are now 10 years or morepostoperative and are reaching adulthood. Therefore, we arenow in a position to assess what has been accomplished bythis novel surgical approach; to compare post-Fontan pro-cedure patients’ present state of well-being with the “naturalhistory” of the various forms of functional single ventriclebefore this operation became available; and to make recom-mendations regarding its continued application in patientsfor whom it might potentially provide benefit.

Criteria for Operability

Choussat and Fontan (2) originally listed “ten anatomic andphysiologic commandments” that they felt must be metbefore this new operative approach could be successfullyapplied. It subsequently became clear that this list was toostringent and that strict criteria regarding age of patients,presence of sinus rhythm, normal systemic and pulmonaryvenous drainage, normal right atrial size, and absence of

mitral valve incompetence were not mandatory to achieve asurgical survivor or a good late result. With the passage oftime it has become clear that the important criteria that mustbe met to obtain a good result involve only the size of thepulmonary arteries, the level of the pulmonary arteriolarresistance, and the status of the systolic and diastolic func-tion of the potential patient’s single ventricle. As experiencewith the procedure increased, institutions with a large andon-going patient population have established and publishedmodifications of the original criteria in these areas andwell-recognized guidelines for patient selection now exist(3,4).

Surgical Techniques

Fontan advocated placing caval valves and using a valvedright atrium to hypoplastic right ventricle conduit in hissurgical patients with tricuspid atresia (1). It subsequentlybecame clear that the caval valves do not function well anddeteriorate rapidly and that a hypoplastic right ventricle wasnot necessary to propel the systemic venous blood into thelungs. An experimental model in the late 1980s (5) demon-strated that flow turbulence and energy losses are reducedwhen pulsation in a valveless chamber is eliminated andflow pathways are streamlined maximally with eliminationof corners. This study proposed total cavopulmonary con-nections with exclusion of most of the right atrium, a con-cept which they felt also might reduce the incidence ofpostoperative atrial dysrhythmias as well as improve hemo-dynamics. In recent years this concept has gained wide favorand presently, in most major centers, the superior vena cavais anastomosed directly to the pulmonary arteries and infe-rior vena cava blood is then routed to the pulmonary arterieseither via a “lateral tunnel” (6) within the right atrium or viaan entirely extracardiac pathway with the medial aspect ofthis pathway located along the lateral border of the rightatrium. The questions of whether to “fenestrate” the inferiorvena caval pathway and whether it is necessary to “stage” theFontan procedure by performing a bi-directional superiorvena cava to pulmonary artery anastomosis as a preliminaryoperation before completing the Fontan circulation by di-recting inferior vena caval blood directly to the pulmonaryarteries as a “second stage” remain controversial (7). Someinstitutions have favored these approaches in attempting todecrease operative mortality. At the Mayo Clinic, however,we continue to favor the non-fenestrated non-staged ap-proach in low risk surgical candidates, reserving fenestrationand/or staging for those patients who present a somewhatincreased operative risk secondary to mildly compromisedventricular function, borderline-sized pulmonary arteries,or who may require concomitant atrioventricular valve re-pair or replacement, or subaortic resection at the time oftheir Fontan procedure.

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Operative and Late Results

As improved patient selection criteria and surgical tech-niques have evolved, and acute perioperative managementimproved, the operative mortality rate for the Fontan proce-dure has been dramatically reduced even for the more com-plex forms of single ventricle. Operative mortality for thenon-fenestrated one-stage Fontan procedure at our institu-tion is now ,5% for the lesions of tricuspid atresia anddouble inlet left ventricle and ,10% for the more complexsingle ventricle malformations such as those associated withasplenia and polysplenia, pulmonary atresia with intact ven-tricular septum, and single ventricle of right ventricularmorphology (8). The trend in recent times to perform theprocedure at a younger age, during the early childhoodyears, is no doubt also responsible in part for the improvedoperative results, as such patients whose functional singleventricle has not been subjected to many years of hypoxemiaand volume overloading usually do not have significantimpairment of systolic or diastolic ventricular function at thetime of operation and are less likely to have associatedproblems such as significant atrioventricular valve regurgi-tation or subaortic obstruction.

With many operative survivors now 10 to 20 years post-Fontan procedure and reaching adulthood, information isnow becoming available regarding the late results of theoperation and the quality of life which it affords. At the MayoClinic more than 900 Fontan procedures have been per-formed for the various forms of functional single ventricle.Some late deaths have occurred as a result of reoperation(usually for atrioventricular valve replacement), sudden dys-rhythmia, thromboembolism, gradual myocardial deteriora-tion and secondary congestive heart failure, and proteinlosing enteropathy. A recent review of the 216 patients withtricuspid atresia who had the Fontan procedure at the MayoClinic between 1973 and 1996 revealed 26 late deathsamong the 197 operative survivors, an incidence of 13%.The deaths occurred between 9 months and 18 years post-Fontan. Statistical analysis of this group revealed a signifi-cantly improved Kaplan-Meier late survival curve for pa-tients operated upon during the most recent decade, againlikely a reflection of improving patient selection and gener-ally younger age at the time of operation.

Because the Fontan procedure, as originally performed,involved multiple suture lines within the atrium and ex-posed the right atrium to increased pressure and wall ten-sion after completion, it was recognized that postoperativeatrial dysrhythmias might be a concern. Follow-up studieshave established that 10 to 20% of patients may have par-oxysmal atrial tachycardia or atrial flutter-fibrillation (9).Although such rhythm disturbances are usually amenable tomedical therapy with good results, in occasional instancesthey may be quite refractory to drug therapy, requiring more

aggressive treatment such as overdrive pacing or a surgicalintervention like the Maze procedure to effectively control.However, the evolution of newer surgical techniques for theFontan operation such as the “extracardiac Fontan” wherethe right atrium does not have multiple suture lines and alsodoes not have large portions of its wall exposed to increasedwall tension, offer promise for a reduced incidence of trou-blesome atrial dysrhythmias in future operative survivors.

The potential for right heart thromboembolism in thepostoperative Fontan patient is of concern because of thenon-pulsatile nature of the circulation and the decreasedcardiac output these patients may manifest. In the largeMayo Clinic experience, two patients dying some years aftersurgery demonstrated, at autopsy, large right atrial thrombiwith evidence of thrombotic pulmonary emboli as well. Twoadditional patients operated on early in the series who had avalved conduit used in the right heart reconstruction, asurgical practice long since abandoned, died late as a resultof thrombotic conduit occlusion. Postoperative follow-up atour institution routinely involves echo-Doppler examina-tion, one of the purposes of which is to look for right heartthrombi and we have, in a small number of cases, seenlaminated thrombi in the right atrium or cavae, but have not,to date, seen a case where it was obstructing the right heartpathways. The decision whether to routinely place the post-Fontan patient on long-term warfarin anticoagulant therapybecause of the potential for thromboembolism remains con-troversial, but it has not been our policy to do so. Again, withthe new surgical techniques which “streamline” the flow ofblood through the right heart and decrease the right atrialvolume, it is hoped that the potential for thrombus forma-tion may be reduced.

With the elevation of systemic venous pressure an inevi-table consequence of the Fontan procedure, it had beenrealized that the potential would exist for the developmentof protein losing enteropathy, a complication seen previ-ously in patients with constrictive pericarditis and second-arily elevated systemic venous pressures. A recent reviewfrom our institution (10) revealed that the risk of develop-ment of protein losing enteropathy was 13.4% after 10 years.Although in a significant number of patients it may be mildin degree and not produce clinical manifestations, in othersit may be significant and produce varying degrees of hy-poalbuminemia with secondary pleural effusions, ascites,etc. Medical therapy with anticongestive measures and albu-min infusion may produce improvement in some symptom-atic patients. In our experience, the addition of corticoste-roids, as advocated by some, has not been beneficial. Morerecently “fenestration” of the atrial baffle, either surgically orin the catheterization laboratory, which reduces right atrialpressure and increases cardiac output although at the ex-pense of some arterial hypoxemia, has been reported, insome cases, to improve or eliminate protein losing enterop-

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athy (11). Very recently the use of heparin therapy on aperiodic basis has been advocated as effective treatment forthis complication. On occasion when the patient is refrac-tory to all other measures and is continuing to deteriorate,cardiac transplantation is considered and it has been suc-cessful in some patients in reversing this potentially debili-tating and fatal complication.

A frequently raised question, as many of our female Fon-tan patients reach adulthood, is the advisability of preg-nancy. Pregnancy and eventual delivery place increaseddemands on the cardiovascular system and these post-Fon-tan patients have a limited ability to increase their cardiacoutput. They also have increased venous pressures and atendency toward fluid retention, factors which are also ex-acerbated by pregnancy. We have recently surveyed ouradult female post-Fontan population in an attempt to deter-mine pregnancy outcomes (12). Although these patients didseem to exhibit an increased incidence (33%) of spontane-ous first trimester miscarriage, in those who did not miscarrythere were 15 live births from 14 different mothers. Only onechild was born significantly prematurely and all 15 infants,including the premature baby, are presently doing well. Theonly congenital heart disease in the offspring was one secun-dum atrial septal defect. In addition, all of the 14 mothers,including the one mother who had two children, seemed totolerate their pregnancies well, had no special problems atthe time of delivery, and feel that their postpartum state ofhealth has not been compromised when compared withtheir antepartum condition. Thus, although this series issmall, it was concluded that potential mothers who weredesirous of having a child, and who had had a good clinicalresult, did have a good chance of a successful pregnancywithout putting themselves at substantial risk and that theprior tendency to routinely discourage pregnancy in thesewomen should be re-evaluated.

The great majority of our more than 600 patients pres-ently surviving, nearly 90% in recent follow-up surveys, areNew York Heart Association class I or class II, capable offull-time school or employment and leading good qualitylives. Many are now more than 10 years postoperative andreaching their adulthood years. A recent follow-up survey ofour 89 presently surviving Fontan patients who had theirprocedure performed as adults (age 18 or older) and whocould therefore remember well their preoperative status,revealed that 89% of these patients felt the quality of theirlife had been improved by the surgery, 51% markedly so.

Conclusion

Before the Fontan approach was formulated, patients with afunctional single ventricle had a natural history character-ized by gradually increasing disability secondary to progres-sive hypoxemia and ventricular myocardial deterioration. Inpatients who did survive the childhood years, their quality of

life was usually significantly impaired by adolescence andsurvival beyond early adulthood was uncommon. The initial25 year experience with the Fontan operation has beengenerally gratifying. Well-established selection criteria forpotential patients has evolved and for such properly selectedpatients operative risk is now ,5% in the simple lesions and,10% in the more complex forms of single ventricle. Al-though follow-up reveals a significant late mortality andmorbidity, surgical advances and the tendency to now per-form the operation earlier in life, before serious ventricularimpairment has occurred, leads to optimism that these prob-lems will be less prevalent in patients presently undergoingthe procedure. Clearly, additional time must pass beforefirm conclusions can be drawn regarding the benefits of thisoperative procedure which represents a palliative approachfor a group of complex congenital heart disease lesions forwhich correction is not possible. However, the initial 25 yearexperience suggests that the Fontan procedure has been amajor step forward in providing help and hope to a group ofpatients with among the most severe forms of congenitalheart disease and that children currently undergoing theprocedure have an excellent chance of surviving the opera-tion and leading good quality lives into their adult years.

Address correspondence and reprint requests to Douglas D. Mair, MD, MayoClinic, 200 First Street SW, Rochester, MN 55905.

REFERENCES

1. Fontan F, Baudet E. Surgical repair for tricuspid atresia. Thorax 1971;26:240–8.

2. Choussat A, Fontan F, Besse P, Vallot F, Chauve A, Bricaud H. Selec-tion criteria for the Fontan procedure. In Anderson RH, Shinbourne EA,eds. Pediatric Cardiology. Edinburgh: Churchill Livingstone, 1978:559–66.

3. Mair DD, Hagler DJ, Puga FJ, Schaff HV, Danielson GK. Fontanoperation in 176 patients with tricuspid atresia: Results and a proposed newindex for patient selection. Circulation 1990;82 (Suppl IV):164–9.

4. Mair DD, Hagler DJ, Julsrud PR, Puga FJ, Schaff HV, Danielson GK.Early and late results of the modified Fontan procedure for double inlet leftventricle: The Mayo Clinic experience. J Am Coll Cardiol 1991;18:1727–32.

5. De Leval MR, Kilner P, Gewillig M, Bull L. Total cavopulmonaryconnection: A logical alternative to atriopulmonary connection for complexFontan operations. Experimental studies and early clinical experience.J Thorac Cardiovasc Surg 1988;96:682–95.

6. Puga FJ, Chiavarelli M, Hagler DJ. Modifications of the Fontan opera-tion applicable to patients with left atrioventricular valve atresia or singleatrioventricular valve. Circulation 1987;76 (Suppl III):53–60.

7. Bridges ND, Lock JE, Lastaneda AR. Baffle fenestration with subsequenttranscatheter closure: Modification of the Fontan operation for patients atincreased risk. Circulation 1990;82:1681–9.

8. Cetta F, Feldt RH, O’Leary PW, et al. Improved early morbidity andmortality after Fontan operation: The Mayo Clinic experience, 1987 to1992. J Am Coll Cardiol 1996;28:2:480–6.

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9. Porter CJ, Garson A. Incidence and management of dysrhythmias afterFontan procedure. Herz 1993;18:5:318–27.

10. Feldt RH, Driscoll DJ, Offord KP, et al. Protein losing enteropathy afterthe Fontan operation. J Thorac Cardiovasc Surg 1996;112:3:672–80.

11. Mertens L, Dumoulin M, Gewillig M. Effect of percutaneous fenestra-tion of the atrial septum on protein-losing enteropathy after the Fontanoperation. Br Heart J 1994;72:591–2.

12. Canobbio MM, Mair DD, Van Der Velde M, Koos BJ. Pregnancyoutcomes after the Fontan repair. J Am Coll Cardiol 1996;28:3:763–7.

PERSPECTIVEEchocardiographic Evaluation ofCongenital Heart DiseaseWilliam F. Armstrong, MD, Echocardiography Laboratory, Division of Cardiology,University of Michigan, Ann Arbor, Michigan

Because two-dimensional echocardiography can identifyand characterize all four chambers and the great vessels, it iscapable of establishing the diagnosis of virtually any form ofcongenital cardiac disease in both infants and children.Combined with physiologic assessments from color-flowand spectral Doppler imaging, physiologic information canbe obtained as well, resulting in a comprehensive and accu-rate evaluation of congenital heart disease (CHD) whichoften precludes the necessity for cardiac catheterization fordiagnosis.

It should be recognized that the spectrum of CHD inadults differs substantially from that seen in infants andchildren. In pediatric populations more complex lesionshave a relative predominance, while in adults simpler lesionssuch as atrial septal defect (ASD) tend to predominate. Thereason for this is a selection over time, in that youngerpatients with significant CHD are more often detected andrepaired in childhood. The most common congenital cardiaclesion to “escape” detection until adulthood is the uncom-plicated ASD. There are rarer instances of small ventricularseptal defects (VSDs), persistent ductus arteriosus and co-arctation of the aorta which likewise escape detection untiladulthood. Similarly, the diagnosis of Ebstein’s anomalymay not be made until adulthood. Other lesions, especiallythose resulting in cyanosis such as tetralogy of Fallot, singleventricle, large ventricular septal defect, etc., are virtually alldiagnosed in infancy and childhood. Many of these lesionsdo not allow survival to adulthood without palliative orcorrective surgery.

The echocardiographic evaluation of CHD requires spe-cific attention to several parameters not usually evaluated in

adult populations. These include particular attention to thesystemic and pulmonary veins with respect to their inflowpatterns and cardiac situs. Subcostal views as well as viewsfrom the right chest may be necessary for complete charac-terization. Transesophageal echocardiography (TEE) obvi-ously will provide incremental information with respect toimage quality, and in many instances with respect to diag-nostic information. Pertinent points regarding specific con-genital lesions follow.

ASD

The ASD is the most common congenital lesion to escapedetection into adulthood. In many instances it is an isolateddefect allowing survival into the fourth, fifth and even sixthdecades of life with minimal or no symptoms. ASDs result inleft to right shunting with a right ventricular (RV) andpulmonary blood flow overload pattern which eventuallyresults in right heart dilation, potentially subsequent pulmo-nary hypertension and, in its advanced stages, atrial arrhyth-mias and RV failure. Patients may remain asymptomaticwell into the fourth and fifth decades of life even withlarge atrial septal defects. The three predominant types ofASDs are the secundum ASD, primum ASD and sinusvenosus ASD. These can be accurately diagnosed andcharacterized using echocardiographic techniques. Rarerforms of ASDs, such as the unroofed coronary sinus, canlikewise be diagnosed.

From an echocardiographic standpoint, the hallmark ofan ASD is a RV volume overload pattern with dilation of theright ventricle and flattening of the ventricular septum indiastole. The interventricular septum assumes circular ge-ometry in systole. It should be emphasized that this patternwill be seen in any RV diastolic volume overload includingsignificant tricuspid regurgitation, pulmonic regurgitationor anomalous pulmonary venous return. Using moderntransthoracic scanners it is frequently possible to directlyvisualize the ASD and characterize it as primum, secundumor sinus venosus. The latter is substantially more likely toelude direct visualization than are primum and secundumdefects. If a defect is not directly visualized, color-flowDoppler imaging can often give clues as to the presence of anabnormal atrial level shunt and contrast echocardiographycan be used to demonstrate right to left shunting. In in-stances in which an ASD is suspected but not directlyvisualized, its presence can be confirmed in virtually allinstances by TEE. It is most commonly a sinus venosus ASDin which TEE is required to establish the diagnosis. Inaddition to making the diagnosis and localizing the defect,TEE can be utilized to determine its precise size and theintegrity of the atrial septal tissue. This may have particularpertinence in the future as percutaneous closure devicesbecome available. In young individuals in whom an uncom-plicated ASD has been detected, echocardiography provides

Presented in part at an American College of Cardiology Board ReviewCourse, Indianapolis, IN, September 3–7, 1997. Updated in January 1998.

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