Congenital heart disease THE FONTAN CIRCULATION. Heart 2005; 91: doi: /hrt

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1 Take the online multiple hoie questions assoiated with this artile (see page 846) Correspondene to: Professor Mar Gewillig, Pediatri Cardiology, Gasthuisberg University Hospital, B Leuven, Belgium; mar.gewillig@ uzleuven.be A Congenital heart disease THE FONTAN CIRCULATION Mar Gewillig Heart 2005; 91: doi: /hrt normal mammal ardiovasular system onsists postnatally of a double pulmonary and systemi iruit, onneted in series, powered by a double pump the right and left heart. Many omplex ardia malformations are haraterised by the existene of only one funtional ventrile. This single ventrile then has to maintain both the systemi and the pulmonary blood irulation, whih are not onneted in series but in parallel (fig 1A, B). Suh a iruit has two major disadvantages: arterial desaturation, both at rest and inreasing during exerise, and a hroni volume overload to the single ventrile. Chroni volume overload will in time impair ventriular funtion, ausing from the third deade on a gradual attrition due to ongestive heart failure, with few survivors beyond the fourth deade. In 1971 Franis Fontan 1 from Bordeaux, Frane, reported on a new approah to the operative treatment of these malformations, separating the systemi and pulmonary irulations. In a Fontan irulation the systemi venous return is onneted to the pulmonary arteries without the interposition of an adequate ventrile, and all shunts on the venous, atrial, ventriular and arterial level are interrupted (fig 1C). In suh a Fontan iruit the postapillary energy is no longer wasted into the systemi veins, but olleted and used to push the blood through the lungs. Advantages of a Fontan iruit inlude (near) normalisation of the arterial saturation, and abolishment of the hroni volume overload; the ost for suh a irulation inludes hroni hypertension and ongestion of the systemi veins, and dereased ardia output both at rest and during exerise. 2 Typially for this iruit, ardia output is no longer determined by the heart, but rather by transpulmonary flow (itself mainly determined by pulmonary vasular resistane). INDICATIONS FOR A FONTAN CIRCUIT A univentriular Fontan repair an be onsidered in ardia malformations with a single funtional ventrile, usually beause of the absene of an adequate atrioventriular valve or pumping hamber for example, triuspid atresia, pulmonary atresia with intat ventriular septum, double inlet ventrile, hypoplasti left heart syndrome (fig 2). In other very omplex malformations with high surgial risk morbidity, or need for high maintenane (frequent onduit replaement), a Fontan strategy may offer a lower surgial risk and lower inidene of reinterventions for a similar linial and funtional long term result. SELECTION OF PATIENTS In 1978 Choussat and Fontan 3 desribed their reommendations for a suessful Fontan operation, defined as having a good ardia output at an aeptable systemi venous pressure. These rules have been refined by many entres, but all reflet that after repair left atrial pressure must be low (determined by good ventriular funtion), and that the transpulmonary gradient must be low (determined by the pulmonary vasulature). Cardia requirements nowadays are: unobstruted ventriular inflow (no atrioventriular valve stenosis, no regurgitation), a reasonable ventriular funtion, and unobstruted outflow (no subaorti stenosis, no arterial hypertension, and no oartation). Pulmonary requirements inlude a non-restritive onnetion from systemi veins to the pulmonary arteries (Fontan onnetion), good sized pulmonary arteries without distortion (at repair and later during growth), a well developed distal vasular bed, (near) normal pulmonary vasular resistane, 2.5 U/m 2, and unobstruted pulmonary venous return. As soon as possible following birth, the pre-fontan management must aim to reah these goals; some deviations are aeptable, however, with inreased operative mortality and inreased late morbidity and late mortality. The haemodynami evaluation just before the Fontan surgery must try to predit how lungs and heart will interat after Fontan ompletion. This an be very diffiult beause at the time of Fontan surgery ventriular preload will signifiantly derease (and aording to Frank-Starling also ontratility), and with urrent 839

2 840 Figure 1 (A) The normal ardiovasular irulation. The pulmonary irulation (P) is onneted in series with the systemi irulation (S). The right ventrile maintains the right atrial pressure lower than the left atrial pressure, and provides enough energy to the blood to pass the pulmonary resistane. (B) The patient with a univentriular heart. The systemi and pulmonary iruits are onneted in parallel, with a onsiderable volume overload to the single ventrile (V). The width of the line reflets the degree of volume load. There is omplete admixture of systemi and pulmonary venous blood, ausing arterial oxygen desaturation. (C) The Fontan irulation. The systemi and pulmonary irulations are onneted in series. The right atrium (RA) or systemi veins are onneted to the pulmonary artery (PA). The volume overload to the single ventrile is now less than expeted for body surfae area. In the absene of fenestration, there is no more admixture of systemi and pulmonary venous blood, but the systemi venous pressure is notably elevated. Ao; aorta; LA, left atrium; LV, left ventrile, RV, right ventrile. treatment strategies pulmonary flow will inrease, influening the transpulmonary gradient. All liniians involved in the management of these patients have learned that these preditions are, at best, just that preditions. IS EVERY FONTAN CIRCUIT ALIKE? Sine its original desription, the Fontan iruit has known numerous modifiations. Early on surgeons used valves (avo-atrial, atrioventriular, or atriopulmonary), and reated various onnetions between the right atrium and the pulmonary artery (anterior atriopulmonary onnetion, with or without inlusion of a small hypoplasti right ventrile, posterior atriopulmonary onnetion), and with different materials (valved onduits, homografts, pathes, diret anastomosis). The very high inidene of late reoperations, reahing 40% in some series, reflets the poor design of the first Fontan iruits and the less than ideal surgial tehniques used in the early series. Most of the older iruits are no longer reated and are onsidered obsolete; however, many patients still survive on suh iruits. When assessing a patient with a Fontan iruit, the liniian needs to know exatly whih onnetion has been made with what material. During the last deade the total avopulmonary onnetion has emerged as being superior (fig 3). 4 The aval veins are onneted to the pulmonary artery, bypassing not only the right ventrile but also the right atrium. The superior aval vein is onneted to the pulmonary artery (bidiretional Glenn shunt). There are two variants to onnet the inferior aval vein: the lateral tunnel, and the extra ardia onduit. Introdued in the mid 80s, the lateral tunnel provides a tubular path between the inferior aval vein and the pulmonary artery, onsisting of a prostheti baffle and a portion of the lateral atrial wall. This iruit has growth potential and an therefore be reated in hildren as young as 1 year; it leaves a minimal amount of atrial tissue exposed to high pressure, whih in time may ause atrial arrhythmia. The extraardia onduit was introdued in 1990, and onsists of a tube graft between the transseted inferior aval vein and the pulmonary artery. This iruit leaves the entire atrium at low pressure, has none to minimal atrial suture lines, and an be performed without aorti ross lamping or even ardiopulmonary bypass; however it has no growth potential and therefore will be offered to patients large enough to aept a graft adequate for an adult s inferior aval vein flow. HOW TO ACHIEVE A FONTAN CIRCUIT CURRENTLY At birth, it is impossible to reate a Fontan irulation. The pulmonary vasular resistane is still raised for several weeks, and the vessels aval veins and pulmonary arteries are usually too small, making any avopulmonary shunt impossible during that period. Even when resistane has fallen, a staged approah is preferred onneting the superior and inferior aval veins at separate oasions. Suh a staged approah allows the body to adapt progressively to the very different haemodynami onditions, and redues the overall operative morbidity and mortality. A staged approah also allows a better patient seletion and intermediate preparatory interventions. Initially in the neonatal period, management must aim if not provided by nature to ahieve unrestrited flow from the heart to the aorta (if required, oartetomy, Damus- Kaye-Stansel, Norwood repair), a well balaned limited flow to the lungs (if required, pulmonary artery band, shunt (modified Blalok-Taussig, entral), stent in dut), and unrestrited return of blood to the ventrile (if required, Rashkind balloon septostomy). The infant is then allowed to grow for several months. During this time, the heart is submitted to a hroni volume overload whih is good for the

3 development of the pulmonary vasulature, but if exessive is detrimental for ventriular funtion. The infant will have mild desaturation, inversely related to mild ardia failure. At the age of 4 12 months, most entres will introdue a avopulmonary onnetion or bidiretional Glenn shunt: the superior aval vein is onneted to the pulmonary artery (bilateral if present). If no other blood flow is allowed to the lungs, the volume load to the heart is signifiantly dereased to slightly less than normal for body surfae area (BSA). The patient at this stage will remain slightly yanoti, as the desaturated blood from the inferior aval vein is still allowed to flow to the aorta. At 1 5 years of age, depending on entre preferene, growth of vasular strutures, and yanosis at rest and during exerise, the Fontan iruit is ompleted by onneting the inferior aval vein to the pulmonary artery. As mentioned before, two tehniques are urrently used: the lateral tunnel and the extraardia onduit. Frequently a small fenestration is reated between the tunnel onduit and the pulmonary atrium, either routinely or only in high risk patients. 5 Suh fenestration will allow a residual right-to-left shunt, thereby limiting aval pressure and ongestion, and inreasing preload of the systemi ventrile and ardia output, at the expense of yanosis. Suh fenestration has been shown to redue operative mortality and morbidity (pleural drainage); the fenestration an be losed later (weeks to months) Figure 2 Shemati representation of ardia malformations that are suitable for Fontan repair. Top left: triuspid atresia. Top right: double inlet left ventrile. Bottom left: hypoplasti left heart syndrome. Bottom right: unbalaned atrioventriular septum defet. 841 after adaptation of the body to the new haemodynami ondition. HOW DO OLD (AND CURRENTLY ADULT) CIRCUITS COMPARE WITH CURRENT CIRCUITS? There are several reasons why adults with a Fontan iruit do not reflet where the urrent ohort of patients will be in several deades. The longest survivors of a Fontan operation, urrently adults, were frequently less than ideal andidates for this type of surgery, with many signifiant residua and sequelae related to the ardia malformation and palliative proedures. A shunt proedure undertaken from the 1960s to the 1980s was evaluated by its long term relief of yanosis. The fat that this shunt ould indue mild pulmonary vasular disease, ventriular dysfuntion, or pulmonary artery distortion was not the first preoupation of the surgeon, as it is now. The suess of a shunt is urrently evaluated by an aeptable relief of yanosis without a signifiant volume overload, by its indution of pulmonary growth without an impairing effet on the pulmonary vasulature, even not during growth after Fontan repair, and by allowing the patient to reah an age at whih a Fontan iruit an be safely reated. Moreover, many entres have attempted to determine whih ombination of riteria ould be ignored without ompromising a suessful outome. 6 Fontan iruits have previously been performed on patients who would probably

4 842 not now be onsidered for suh repair. Those unsuitable andidates who survived the operation obviously represent the poorer end of the linial spetrum of results after Fontan orretion, and will distort all reports on long term results. The hange in management has ontributed to a higher proportion of patients with a univentriular heart that fulfil most riteria for a suessful Fontan repair. Exessive ventriular dilation, spherial reonfiguration, ardia overgrowth, ventriular dysfuntion, and mild pulmonary vasular disease or distortion are now rarely seen. Operative mortality has signifiantly dereased to less than 5%, with better iruits having a life time potential. We expet the urrent ohort of patients to perform better than the early series, also at a later age. COMPLETE FONTAN VERSUS BIDIRECTIONAL GLENN WITH ADDITIONAL FLOW When reating the Glenn shunt, the option exists to maintain the original pulmonary blood flow soure (pulmonary stenosis or band, shunt ontralateral to the superior aval vein). If this flow is limited, the extra pressure load on the superior aval vein is usually well tolerated, with the benefit of extra growth of the pulmonary arteries and higher arterial saturations during this stage of palliation. It was hoped that suh a iruit might be a satisfatory final palliation. However, most hildren outgrow the limited pulmonary blood flow, with inreasing yanosis espeially during exerise. Most of these patients will eventually be onverted to a full Fontan irulation. COMPLICATIONS OF THE FONTAN CIRCULATION Compliations after Fontan repair are ommon and related to the inreased venous pressure and ongestion, and hroni low ardia output. Compliations inlude early and late mortality, mild to moderate exerise intolerane, residual ardiomegaly, ventriular dysfuntion, rhythm and ondution disturbanes, hepatomegaly, lymphati dysfuntion with protein losing enteropathy, systemi venous thrombi, asites, and peripheral oedema. Late mortality When assessing long term results from a entre, it should be lear that in all series a profound bias ours, firstly when patients are aepted for a Fontan repair, and seondly by the survival following the operation. Both are unavoidable effets when studying long term survivors. Many patients have Figure 3 Angiogram of total avopulmonary onnetion. (A) Injetion in inferior aval vein whih is onneted with a 22 mm Goretex graft to the pulmonary artery; note mild preferential flow to left pulmonary artery. (B) Injetion in right superior aval vein whih is onneted to the right pulmonary artery; note mild preferential flow to right pulmonary artery. survived for several deades. Late death is diretly related to the number of risk fators for a Fontan operation. 7 Poor andidates for a Fontan operation, if they survive due to exellent surgery and outstanding postoperative are, remain at higher risk for late death. Good Fontan physiology allows good survival for several deades, but unfavourable haemodynamis and risk fators are assoiated with an inreased early and late attrition. Funtional status and exerise tolerane Despite the abnormality of the iruit, liniians are frequently impressed by the ability of most patients with a Fontan irulation to lead a nearly normal life, inluding mild to moderate sport ativities. More than 90% of all hospital survivors are in New York Heart Assoiation (NYHA) funtional lass I or II. Most patients progress through the eduation system just like the standard population and an pursue a wide variety of professional areers. 8 However, with time there is a progressive deline of funtional status in some subgroups. A Fontan irulation is palliative in nature, with good results in patients with an ideal haemodynami profile, but with signifiant ongoing morbidity and mortality if some riteria are not met. Ventriular funtion All studies have reported the ventrile of a funtionally univentriular heart to be dilated, hypertrophi and hypoontratile, ertainly after ompletion of a Fontan type of iruit. Ventriular dysfuntion an be aused by the ongenital malformation itself, previous surgial interventions, or the very abnormal working onditions of the ventrile at the various stages of palliation, both before and after Fontan. During the first months after birth, the ventrile will always be volume overloaded, either by a band or by an aorta pulmonary shunt. This volume overload will lead to dilation and spherial reonfiguration, ardia overgrowth, and eentri hypertrophy. After unloading at the time of a Fontan operation, some regression to normalisation will our, but will be frequently inomplete. Before the introdution of the avopulmonary shunt in the 1990s, a large volume overload persisted for several years. Therefore, patients born before the 90s (urrently adults) will frequently have residual dilation, ardia overgrowth, and hypertrophy even into adult age. With urrent treatment strategies only a small

5 shunt is allowed to persist for several months, thereby avoiding suh a situation. The preload to the ventrile is, at the time of a Fontan operation, redued to levels well below normal for BSA (50 70%), and even more when expressed in relation to ventriular size (25 70%). The ventrile thus evolves from being volume overloaded and overstrethed, to overgrown and (severely) underloaded. It should therefore not be a surprise that the deprived ventrile in a Fontan iruit shows systoli and diastoli dysfuntion. The ventrile may now enter a viious yle whereby the low preload results in remodelling, redued ompliane, poor ventriular filling, and eventually ontinuously delining ardia output. This phenomenon of progressive disuse hypofuntion ours at a hroni preload of less than 70% of the due preload. 9 Our knowledge of low flow onditions, hroni ongestion, and limited ventriular preload is, however, still very limited. The ongenital malformation itself may predispose to ventriular dysfuntion. A left ventrile with its unique ellipsoid shape and omplex fibre orientation is tuned to maintain systemi pressure for a life time. In ontrast, a morphologi right ventrile, and even more an undetermined primitive ventrile both frequently enountered in funtionally univentriular hearts may fail after some years of systemi loading. Furthermore, a triuspid valve or a ommon atrioventriular valve poorly tolerate the initial volume overload, and also have problems with the hroni systemi afterload. The treatment of ventriular dysfuntion in the setting of a Fontan iruit is very frustrating for a ardiologist. Lak of reation to lassi treatment strategies has given the ventrile in a Fontan iruit a very bad reputation. Several studies, both aute and hroni, have shown little impat on ventriular funtion of mediation suh as inotropes, afterload reduing agents, vasodilators, and b blokers, as these have no impat on the redued preload whih is the dominant limiting fator. Arrhythmia Patients with a Fontan irulation are predisposed to develop atrial dysrhythmias. Many old iruits have atrial wall inorporated into the iruit ausing atrial dilation and hypertrophy; furthermore, most patients have had an atriotomy, and possible injury to the sinus node or its arterial supply or innervation. Clinially, tahyardia is mostly prevalent in patients with a suboptimal haemodynami result, espeially if the right atrium is dilated and the pulmonary vasular resistane is inreased. The prognosis therefore remains worrying, even if the patient an be reonverted to sinus rhythm. Arrhythmias our with inreasing inidene after Fontan repair in up to 40% of the patients 10 years after surgery. The most ommon atrial tahyardia is intra-atrial re-entry tahyardia or atypial atrial flutter. Suh tahyardia an quikly lead to severe haemodynami deterioration. Survival depends on the ventriular ontratility and the vasular resistane, whih an be ritially altered by most antiarrhythmi drugs. The safest option is therefore immediate diret urrent (DC) shok reonversion. During the subsequent workup, the liniian should obtain a omplete haemodynami evaluation in every patient with a new tahyardia, as this may be the late but first linial manifestation of pathway obstrution and/or thrombi. Full antioagulation should be onsidered in every Fontan patient with atrial arrhythmias in view of the signifiant risk of a right atrial thrombus. Long term treatment of atrial arrhythmia an involve mediation and ablation; progression of the arrhythmia and funtional deline is frequently observed. The best long term investment for these patients is onversion of the old Fontan iruit to an extraardia avopulmonary onnetion, together with a right atrial maze and a redution plasty (ombined with a DDD epiardial paemaker if indiated). 10 It is speulated that the inidene of late atrial tahyardia will derease with the use of avopulmonary onnetions. Only time will tell whether this theoretial advantage will ome true, but results after similar follow up are promising. Ventriular arrhythmias are rare in patients with a Fontan irulation. If present, they are probably related to very poor Fontan haemodynamis or severe ventriular dysfuntion. Hypoxaemia aused by residual new shunts Patients with a Fontan irulation are slightly desaturated with values in the low 90s, even when a residual atrial septum defet had been refuted. The oronary sinus in all reent iruit modifiations drains to the left atrium, ausing a modest arterial desaturation of 2%. Several anatomi substrates may result in a signifiant residual/progressive right-to-left shunt and desaturation: a residual atrial septum defet or fenestration, a oronary sinus to left atrium shunt through a defet or through ardia veins (in older iruits), intrapulmonary arteriovenous fistulae, and abnormal systemi venous drainage to the pulmonary venous atrium (for example, a left superior aval vein to the left atrium). These onnetions may be losed perutaneously as they ause symptomati yanosis. Residual left-to-right shunt Left-to-right shunting may be present beause of aorta pulmonary ollaterals, inomplete ligation of the main pulmonary artery, or failed olusion of previous shunts. These shunts usually ause an unimportant volume load for the systemi ventrile, but also put a useless and sometimes detrimental volume/pressure overload on the pulmonary flow. Any systemi vessel that upon injetion gives a pulmonary apillary blush with opaifiation of the pulmonary veins should be oluded perutaneously. Pulmonary irulation A low pulmonary vasular resistane is mandatory for a good funtioning Fontan iruit. Apart from a few exeptions, pulmonary vasular resistane will ontrol the ardia output. The iruit runs on autopilot, with little interferene possible by the liniian. This has frustrated many ardiologists as they have experiened that their organ no longer ontrols ardia output. Cardia output an be inreased by improving flow to and into the lungs (streamlined nonobstrutive Fontan onnetion, stenting of hypoplasti or stenoti pulmonary artery), or by bypassing the lungs with a fenestration. The effet of pulmonary vasodilators is usually very modest. Pre-Fontan management must aim at perfet growth of pulmonary vasulature. We have now started to realise that an initial mild pulmonary overflow is benefiial for adequate growth of pulmonary vasulature. The optimal balane between a small short lived shunt and a large longstanding shunt, leading inversely to either more or less ardia preservation or pulmonary growth, still needs to be refined. 843

6 844 Pulmonary artery distortion is a reognised late ompliation of most systemi to pulmonary artery shunts. Cliniians should realise that at the time of Fontan repair these shunts are sometimes not divided, but just oluded with a lip. Therefore, the pulmonary artery is still fixed to a systemi artery, whih an ause a distortion of the pulmonary artery late after Fontan repair, espeially during growth. Careful liniians will hoose to atively doument adequate growth of all onnetions and strutures during and ertainly at the end of somati growth. The effet of high altitude and dereased oxygen tension varies widely among individuals. Patients with borderline haemodynamis have been reported to deteriorate autely after moving to moderate altitude above 2000 m. Patients with good haemodynamis and no or little reativity of the pulmonary vasulature do well at moderate altitude. It remains questionable whether patients whose ardia output is sensitive to the pulmonary vasular resistane should be living at inreased altitude. Lymphati dysfuntion: protein losing enteropathy, plasti bronhitis A Fontan irulation operates at or sometimes just beyond the funtional limits of the lymphati system. The superior aval vein pressure is elevated and its runoff dereased, impeding drainage of the thorai dut. Leakage in the interstitium auses lymph oedema or pulmonary oedema, a very lethal ompliation in the early postoperative period. Leakage into the thorax or periardium will lead to hylothorax or hyloperiardium, a ompliation whih usually only ours in the perioperative period, but rarely thereafter beause of adhesions. Leakage into the gut leads to protein losing enteropathy (PLE), the most frequent lymphati problem in long term follow up. Leakage of hyle into the bronhus leads to plasti bronhitis, most frequently diagnosed at neropsy. PLE is aused by intestinal lymphangietasia with leakage of lymphoytes, hylomirons, and serum protein suh as albumin and immunoglobulin into the gut; PLE results in oedema, asites, immunodefiieny, and hypoalaemia. PLE is a relatively rare ompliation: in an international multientre study, 11 involving 35 entres and 3029 patients with Fontan repair between 1975 and 1995, PLE ourred in 114 patients (3.8%, range aross the 35 entres 0 25%). The diagnosis of PLE usually yields a very poor prognosis: after diagnosis, the five year survival rate was 59%, with less than 20% of patients surviving beyond 10 years. Problems in the Fontan iruit (gradient at onnetion, poor design), problems of the pulmonary vasulature (inreased pulmonary vasular resistane, hypoplasia, distortion, loss) or ardia problems (atrioventriular valve regurgitation, myoardial dysfuntion) an frequently be identified. An autoimmune or inflammatory ause, sometimes triggered by an infetion, has also been isolated in some patients. Several treatment strategies have been identified. A diet high in alories, high protein ontent, and medium hain triglyeride fat supplements with low salt ontent is usually reommended. Diuretis an more or less limit peripheral oedema in most patients. Protein infusions (albumin, globulin) an be required on a weekly or monthly basis. In some patients speifi anti-infetion measures are neessary (hroni antibiotis, vaines). Clinial resolution of PLE with only these measures is rare (, 1%). Attempts to augment ardia funtion or output with inotropi drugs or systemi vasodilators are usually unsuessful. Cortiosteroids, high moleular weight heparin, and otrioide aetate may oasionally improve PLE. Some patients are ured for several weeks, months, or years with a single episode of mediation; some patients will have an ongoing need for mediation, while many patients will show no reation at all. Side effets in the long term are important. Hypoxaemia indued pulmonary vasoonstrition an lead to PLE; a long stay at high altitude or even a long flight an trigger PLE in some patients. Most patients with a Fontan iruit will, however, tolerate suh altitude onditions without a problem. Cardia paing in patients with exessive bradyardia or atrioventriular dissoiation an ritially improve ardia funtion and may ure PLE. Resetion of the most affeted part of the gut resulting in linial improvement has been reported. Several surgial options have been reported: relief of obstrution, onversion to streamlined avopulmonary onnetion, atrioventriular valve repair/replaement. However, many of these proedures yield a high mortality, espeially if there is signifiant atrioventriular valve regurgitation and ventriular dysfuntion. Late takedown has been performed in some patients, usually with high mortality. Of all the surgial proedures, heart transplantation is the most preditive, but obviously with its own long term problems. Heart transplantation will improve the haemodynami ondition by inreasing ardia output and dereasing venous ongestion; hroni anti-rejetion therapy may also influene PLE. If the patient survives the transplantation (inreased risk from ahexia, immunologi deregulation), PLE resolves in most patients; rarely it persists or relapses after some years. Several haemodynami problems an be solved with atheter tehniques: balloon dilation, stent implantation of a iruit stenosis or residual vessel hypoplasia; residual left to right shunts (native, surgial, arterial venous ollaterals) an be embolised; a fenestration 12 with stent an safely be reated through the perutaneous (or transhepati) route, even in iruits with an extraardia onduit. Suh fenestration will derease venous ongestion, improve runoff and inrease ardia output, at the expense of arterial saturation, however. PLE nearly always improves with a fenestration, but the range between aeptable PLE and unaeptable yanosis may be narrow; this range frequently further narrows over months, probably beause of seondary hanges in the pulmonary vasulature. Many suh patients will therefore require heart transplantation in the medium term follow up. Plasti bronhitis is a very rare but potentially lethal ompliation ourring weeks to months after the Fontan orretion: it leads to obstrution of major airways by solid fibrinomuoid material. Persistent segmental ateletasis, large airway obstrution, or expetoration of tenaious fibrinomuoid material should prompt early onsideration of diagnosti and therapeuti bronhosopi lavage. Treatment is very diffiult and similar to that for PLE. Reprodution: pregnany Most females after Fontan repair have normal menstrual patterns, making it apparent that pregnany is possible. Pregnany and delivery learly put an inreased load on the ardiovasular system. Normal pregnany is assoiated with an inrease in ardia output of 30 40% by 24 weeks of

7 The Fontan irulation: key points Good Fontan physiology enables survival for several deades, but unfavourable haemodynamis and risk fators are assoiated with poor exerise tolerane and an inreased early and late attrition Following birth, the ventrile tries to adapt to different and very abnormal irulations, evolving from overloaded and overstrethed while shunted, to underloaded and overgrown after a Fontan type of irulation The absene of a linial problem does not equal a satisfatory haemodynami result; possible problems must atively be searhed and resolved before they beome linially relevant Knowledge of low flow onditions, hroni ongestion, and limited ventriular preload is still very limited The Fontan irulation an be a soure of frustration for the ardiologist as, apart from a few exeptions, the heart in a Fontan iruit no longer ontrols ardia output. Conventional anti-failure treatment will yield no linial result Management of atrial tahyardia: the faster the rhythm, the poorer the patient s ondition, the more sars on the hest, the less the liniian understands, the faster he should opt for urgent DC reonversion. gestation, an inrease in the irulating blood volume by 30 40%, but a derease in systemi vasular resistane. Fluid retention and a hyperoaguable state are frequently observed. These hanges result in an inreased systemi venous pressure and may trigger ompliations of right heart failure suh as atrial arrhythmias, oedema, and asites. Any right-to-left shunt through a residual atrial septal defet will inrease; the resultant derease in arterial saturation, however, is usually well tolerated. There is an inreased risk for venous thrombosis and pulmonary embolus. Nevertheless, suessful pregnany with delivery of normal hildren is possible. Women with a good haemodynami result apparently tolerate pregnany and normal delivery well. 13 Therefore, if a woman is doing well both linially and haemodynamially, and strongly desires to beome pregnant, it seems urrently unreasonable to disourage her. However, she and her husband must be made aware that the risk to her and the hild is inreased. The risk for the fetus of having ongenital heart disease is urrently unknown, as women with ardia malformations amenable to Fontan surgery have rarely had offspring. For most malformations the risk will probably vary between 5 10%. Coagulopathies Thrombosis is more likely to our in patients with low ardia output and more than usual atrial and systemi venous dilatation and blood stasis. Fontan patients have an inreased inidene of oagulation fator abnormalities as in any patient with hepati ongestion: protein C, protein S, and antithrombin III defiieny. 14 Thrombosis may ompliate an infetion, espeially when assoiated with dehydration. A systemi venous thrombus may embolise to the pulmonary artery. Massive embolisation may result in shok, arrhythmia, or death; it is the most ommon ause of sudden out-of-hospital death in patients with a Fontan iruit. Chroni multiple pulmonary miroemboli may lead to pulmonary vasular obstrutive disease, a late ompliation whih is partiularly lethal in a Fontan irulation. Some liniians reommend antioagulating every patient with a Fontan iruit; however, there are learly subgroups of patients with a very low risk. Full antioagulation should be presribed in patients with previous thrombi, poor ardia output (frequently assoiated with spontaneous ontrast on eho), ongestion, dilation of venous or atrial strutures, and arrhythmia. If oagulation abnormalities are present, oral ontraeptives should not be presribed. It is not lear if a small dose of aetylsaliyli aid or lopidogrel is benefiial for prevention of venous thrombi in these patients. This disussion over whether or not to antioagulate all patients will dissipate one the new generation of antithromboti drugs beomes available. The failing Fontan A Fontan irulation may beome failing and unbearable beause of persistent ongestion with oedema, low ardia output with very limited exerise tolerane, relapsing tahyardia, protein losing enteropathy, or plasti bronhitis. As explained before, treatment with inotropes, vasodilators, and diuretis will show little result and will frustrate any onventional ardiologist. Frequently a more aggressive approah will be needed aimed at optimising the iruit (stenting of stenosis, embolising ollaterals, onversion to avopulmonary onnetion, right atrial maze); if this is insuffiient, fenestration and heart transplantation should be onsidered. CONCLUSIONS The long term results of the Fontan operation performed in patients with a low risk profile show good overall results: arterial hypoxaemia is eliminated, volume overload to the single ventrile is abolished, the expense of hroni systemi venous hypertension is usually aeptable, and most patients enjoy a good quality of life. However, sequelae persist in less than ideal patients, whih are frequently progressive and assoiated with a delining funtional result and even premature death. This should remind every liniian that a Fontan operation remains an imperfet solution for a omplex ardiovasular problem. REFERENCES 1 Fontan F, Baudet E. Surgial repair of triuspid atresia. Thorax 1971;26: The original desription of the first Fontan operation: a historial landmark, however with a iruit whih nowadays would be onsidered obsolete. 2 Gewillig M, Kalis N. Pathophysiologi aspets after avo-pulmonary anastomosis. Thora Cardiovas Surg 2000;48: Extensive review of the effets of different pre-fontan treatment strategies on ventriular size and funtion. 3 Choussat A, Fontan F, Besse F, et al. Seletion riteria for Fontan s proedure. In: Anderson R, Shinebourne E, eds. Paediatri ardiology. Edinburgh: Churhill Livingstone, 1978: De Leval M, Kilner P, Gewillig M, et al. Total avopulmonary onnetion: a logial alternative to atriopulmonary onnetion for omplex Fontan operations. Experimental studies and early linial experiene. J Thora Cardiovas Surg 1988;96: Elegant disussion on advantages of avopulmonary onnetions versus atriopulmonary onnetion. 5 Bridges ND, Lok JE, Castaneda AR. Baffle fenestration with subsequent transatheter losure. Modifiation of the Fontan operation for patients at inreased risk. Cirulation 1990;82: Knott-Craig CJ, Danielson GK, Shaff HV, et al. The modified Fontan operation. An analysis of risk fators for early postoperative death or takedown in 702 onseutive patients from one institution. J Thora Cardiovas Surg 1995;109: Exellent report of early results of Fontan repair in patients with a wide range of malformations and less than ideal haemodynamis, most of whih urrently would no longer be onsidered for Fontan repair. Therefore, this study annot be repeated and yields very important information. 845

8 846 7 Drisoll DJ, Offord KP, Feldt RH, et al. Five- to fifteen-year follow-up after Fontan operation. Cirulation 1992;85: Exellent report of late results of Fontan repair in patients with a wide range of malformations and less than ideal haemodynamis, most of whih urrently would no longer be onsidered for Fontan repair. 8 Mair D, Puga F, Danielson G. Late funtional status of survivors of the Fontan proedure performed during the 1970s. Cirulation 1992;86: Silverstein DM, Hansen DP, Ojiambo HP, et al. Left ventriular funtion in severe pure mitral stenosis as seen at the Kenyatta National Hospital. Am Heart J 1980;99: This is urrently one of the few reports addressing the issue of hroni deprivation of a ventrile. 10 Mavroudis C, Deal BJ, Baker CL. The benefiial effets of total avopulmonary onversion and arrhythmia surgery for the failed Fontan. Semin Thora Cardiovas Surg Pediatr Card Surg Annu 2002;5: Very good review on how to manage a failing Fontan iruit. MULTIPLE CHOICE QUESTIONS Eduation in Heart Interative (/mis/eduation.shtml) 11 Mertens L, Hagler D, Sommerville J, et al. Protein losing enteropathy after the Fontan operation: an international multienter evaluation. J Thora and Cardiovas Surg 1998;115: This is a unique report on the rare ompliation of PLE: as it is an anonymous multientre evaluation, many ases whih would otherwise never be reported have been inluded. 12 Mertens L, Dumoulin M, Gewillig M. Effet of perutaneous fenestration of the atrial septum on protein-losing enteropathy after the Fontan operation. Br Heart J 1994;72: Therrien J, Warnes C, Daliento L, et al. Canadian Cardiovasular Soiety Consensus Conferene 2001 update: reommendations for the management of adults with ongenital heart disease part III. Can J Cardiol 2001;17: Monagle P, Karl TR. Thromboemboli problems after the Fontan operation. Semin Thora Cardiovas Surg Pediatr Card Surg Annu 2002;5: Very good review onentrating on evidene based strategies in this diffiult topi. There are six multiple hoie questions assoiated with eah Eduation in Heart artile (these questions have been written by the authors of the artiles). Eah artile is submitted to EBAC (European Board for Areditation in Cardiology; for 1 hour of external CPD redit. How to find the MCQs: Clik on the Online Learning: [Take interative ourse] link on the table of ontents for the issue online or on the Eduation in Heart olletion (/gi/olletion/heart_eduation). Free aess: This link will take you to the BMJ Publishing Group s online learning website. Your Heart Online user name and password will be reognised by this website. As a Heart subsriber you have free aess to these MCQs but you must register on the site so you an trak your learning ativity and reeive redit for ompleted ourses. How to get aess: If you have not yet ativated your Heart Online aess, please do so by visiting and entering your six digit (all numeri) ustomer number (found above your address label with your print opy). If you have any trouble ativating or using the site please ontat subsriptions@bmjgroup.om Case based Heart: You might also be interested in the interative ases published in assoiation with Heart (