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The Fontan Procedure: What Have We Learned and Accomplished?
CONGENITAL HEART DISEASE
mitral valve incompetence were not mandatory to achieve a surgical survivor or a good late result. With the passage of time it has become clear that the important criteria that must be met to obtain a good result involve only the size of the pulmonary arteries, the level of the pulmonary arteriolar resistance, and the status of the systolic and diastolic function of the potential patient’s single ventricle. As experience with the procedure increased, institutions with a large and on-going patient population have established and published modifications of the original criteria in these areas and well-recognized guidelines for patient selection now exist (3,4).
UPDATE
The Fontan Procedure: What Have We Learned and Accomplished? Douglas D. Mair, MD, Mayo Clinic and Mayo Foundation, Rochester, Minnesota In 1969 Fontan performed his first pioneering operation on a patient with tricuspid atresia designed to completely separate the systemic and pulmonary circulations and thereby eliminate the systemic arterial hypoxemia and left ventricular volume overload which were the hallmarks of this condition (1). Although this procedure, which subsequently bore his name, was not truly corrective because of its inability to establish a two-ventricle circulation, it was potentially a higher grade of palliation than what had been previously provided through various shunting operations which did not completely separate the two circulations and which often added substantially to the volume load on the single functional left ventricle. It was recognized at the onset, however, that the elevated systemic venous pressures inevitably present in the post-Fontan patient, necessary to propel the blood through the lungs in the absence of a “booster pump” on the right side of the circulation, might lead to late complications in surgical survivors and that functional limitations would likely still exist in these patients, particularly in physical activities requiring a substantial increase in cardiac output. More than 25 years have past since Fontan’s initial procedure, it has undergone many technical modifications, a surgical evolution which still continues, and its use has been expanded and applied to many anatomic types of functional single ventricle in addition to tricuspid atresia. Several thousands of patients around the world have had the procedure and many surgical survivors are now 10 years or more postoperative and are reaching adulthood. Therefore, we are now in a position to assess what has been accomplished by this novel surgical approach; to compare post-Fontan procedure patients’ present state of well-being with the “natural history” of the various forms of functional single ventricle before this operation became available; and to make recommendations regarding its continued application in patients for whom it might potentially provide benefit.
Surgical Techniques Fontan advocated placing caval valves and using a valved right atrium to hypoplastic right ventricle conduit in his surgical patients with tricuspid atresia (1). It subsequently became clear that the caval valves do not function well and deteriorate rapidly and that a hypoplastic right ventricle was not necessary to propel the systemic venous blood into the lungs. An experimental model in the late 1980s (5) demonstrated that flow turbulence and energy losses are reduced when pulsation in a valveless chamber is eliminated and flow pathways are streamlined maximally with elimination of corners. This study proposed total cavopulmonary connections with exclusion of most of the right atrium, a concept which they felt also might reduce the incidence of postoperative atrial dysrhythmias as well as improve hemodynamics. In recent years this concept has gained wide favor and presently, in most major centers, the superior vena cava is anastomosed directly to the pulmonary arteries and inferior vena cava blood is then routed to the pulmonary arteries either via a “lateral tunnel” (6) within the right atrium or via an entirely extracardiac pathway with the medial aspect of this pathway located along the lateral border of the right atrium. The questions of whether to “fenestrate” the inferior vena caval pathway and whether it is necessary to “stage” the Fontan procedure by performing a bi-directional superior vena cava to pulmonary artery anastomosis as a preliminary operation before completing the Fontan circulation by directing inferior vena caval blood directly to the pulmonary arteries as a “second stage” remain controversial (7). Some institutions have favored these approaches in attempting to decrease operative mortality. At the Mayo Clinic, however, we continue to favor the non-fenestrated non-staged approach in low risk surgical candidates, reserving fenestration and/or staging for those patients who present a somewhat increased operative risk secondary to mildly compromised ventricular function, borderline-sized pulmonary arteries, or who may require concomitant atrioventricular valve repair or replacement, or subaortic resection at the time of their Fontan procedure.
Criteria for Operability Choussat and Fontan (2) originally listed “ten anatomic and physiologic commandments” that they felt must be met before this new operative approach could be successfully applied. It subsequently became clear that this list was too stringent and that strict criteria regarding age of patients, presence of sinus rhythm, normal systemic and pulmonary venous drainage, normal right atrial size, and absence of
ACC CURRENT JOURNAL REVIEW May/June 1998 © 1998 by the American College of Cardiology Published by Elsevier Science Inc.
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CONGENITAL HEART DISEASE
aggressive treatment such as overdrive pacing or a surgical intervention like the Maze procedure to effectively control. However, the evolution of newer surgical techniques for the Fontan operation such as the “extracardiac Fontan” where the right atrium does not have multiple suture lines and also does not have large portions of its wall exposed to increased wall tension, offer promise for a reduced incidence of troublesome atrial dysrhythmias in future operative survivors. The potential for right heart thromboembolism in the postoperative Fontan patient is of concern because of the non-pulsatile nature of the circulation and the decreased cardiac output these patients may manifest. In the large Mayo Clinic experience, two patients dying some years after surgery demonstrated, at autopsy, large right atrial thrombi with evidence of thrombotic pulmonary emboli as well. Two additional patients operated on early in the series who had a valved conduit used in the right heart reconstruction, a surgical practice long since abandoned, died late as a result of thrombotic conduit occlusion. Postoperative follow-up at our institution routinely involves echo-Doppler examination, one of the purposes of which is to look for right heart thrombi and we have, in a small number of cases, seen laminated thrombi in the right atrium or cavae, but have not, to date, seen a case where it was obstructing the right heart pathways. The decision whether to routinely place the postFontan patient on long-term warfarin anticoagulant therapy because of the potential for thromboembolism remains controversial, but it has not been our policy to do so. Again, with the new surgical techniques which “streamline” the flow of blood through the right heart and decrease the right atrial volume, it is hoped that the potential for thrombus formation may be reduced. With the elevation of systemic venous pressure an inevitable consequence of the Fontan procedure, it had been realized that the potential would exist for the development of protein losing enteropathy, a complication seen previously in patients with constrictive pericarditis and secondarily elevated systemic venous pressures. A recent review from our institution (10) revealed that the risk of development of protein losing enteropathy was 13.4% after 10 years. Although in a significant number of patients it may be mild in degree and not produce clinical manifestations, in others it may be significant and produce varying degrees of hypoalbuminemia with secondary pleural effusions, ascites, etc. Medical therapy with anticongestive measures and albumin infusion may produce improvement in some symptomatic patients. In our experience, the addition of corticosteroids, as advocated by some, has not been beneficial. More recently “fenestration” of the atrial baffle, either surgically or in the catheterization laboratory, which reduces right atrial pressure and increases cardiac output although at the expense of some arterial hypoxemia, has been reported, in some cases, to improve or eliminate protein losing enterop-
Operative and Late Results As improved patient selection criteria and surgical techniques have evolved, and acute perioperative management improved, the operative mortality rate for the Fontan procedure has been dramatically reduced even for the more complex forms of single ventricle. Operative mortality for the non-fenestrated one-stage Fontan procedure at our institution is now ,5% for the lesions of tricuspid atresia and double inlet left ventricle and ,10% for the more complex single ventricle malformations such as those associated with asplenia and polysplenia, pulmonary atresia with intact ventricular septum, and single ventricle of right ventricular morphology (8). The trend in recent times to perform the procedure at a younger age, during the early childhood years, is no doubt also responsible in part for the improved operative results, as such patients whose functional single ventricle has not been subjected to many years of hypoxemia and volume overloading usually do not have significant impairment of systolic or diastolic ventricular function at the time of operation and are less likely to have associated problems such as significant atrioventricular valve regurgitation or subaortic obstruction. With many operative survivors now 10 to 20 years postFontan procedure and reaching adulthood, information is now becoming available regarding the late results of the operation and the quality of life which it affords. At the Mayo Clinic more than 900 Fontan procedures have been performed for the various forms of functional single ventricle. Some late deaths have occurred as a result of reoperation (usually for atrioventricular valve replacement), sudden dysrhythmia, thromboembolism, gradual myocardial deterioration and secondary congestive heart failure, and protein losing enteropathy. A recent review of the 216 patients with tricuspid atresia who had the Fontan procedure at the Mayo Clinic between 1973 and 1996 revealed 26 late deaths among the 197 operative survivors, an incidence of 13%. The deaths occurred between 9 months and 18 years postFontan. Statistical analysis of this group revealed a significantly improved Kaplan-Meier late survival curve for patients operated upon during the most recent decade, again likely a reflection of improving patient selection and generally younger age at the time of operation. Because the Fontan procedure, as originally performed, involved multiple suture lines within the atrium and exposed the right atrium to increased pressure and wall tension after completion, it was recognized that postoperative atrial dysrhythmias might be a concern. Follow-up studies have established that 10 to 20% of patients may have paroxysmal atrial tachycardia or atrial flutter-fibrillation (9). Although such rhythm disturbances are usually amenable to medical therapy with good results, in occasional instances they may be quite refractory to drug therapy, requiring more
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CONGENITAL HEART DISEASE
life was usually significantly impaired by adolescence and survival beyond early adulthood was uncommon. The initial 25 year experience with the Fontan operation has been generally gratifying. Well-established selection criteria for potential patients has evolved and for such properly selected patients operative risk is now ,5% in the simple lesions and ,10% in the more complex forms of single ventricle. Although follow-up reveals a significant late mortality and morbidity, surgical advances and the tendency to now perform the operation earlier in life, before serious ventricular impairment has occurred, leads to optimism that these problems will be less prevalent in patients presently undergoing the procedure. Clearly, additional time must pass before firm conclusions can be drawn regarding the benefits of this operative procedure which represents a palliative approach for a group of complex congenital heart disease lesions for which correction is not possible. However, the initial 25 year experience suggests that the Fontan procedure has been a major step forward in providing help and hope to a group of patients with among the most severe forms of congenital heart disease and that children currently undergoing the procedure have an excellent chance of surviving the operation and leading good quality lives into their adult years.
athy (11). Very recently the use of heparin therapy on a periodic basis has been advocated as effective treatment for this complication. On occasion when the patient is refractory to all other measures and is continuing to deteriorate, cardiac transplantation is considered and it has been successful in some patients in reversing this potentially debilitating and fatal complication. A frequently raised question, as many of our female Fontan patients reach adulthood, is the advisability of pregnancy. Pregnancy and eventual delivery place increased demands on the cardiovascular system and these post-Fontan patients have a limited ability to increase their cardiac output. They also have increased venous pressures and a tendency toward fluid retention, factors which are also exacerbated by pregnancy. We have recently surveyed our adult female post-Fontan population in an attempt to determine pregnancy outcomes (12). Although these patients did seem to exhibit an increased incidence (33%) of spontaneous first trimester miscarriage, in those who did not miscarry there were 15 live births from 14 different mothers. Only one child was born significantly prematurely and all 15 infants, including the premature baby, are presently doing well. The only congenital heart disease in the offspring was one secundum atrial septal defect. In addition, all of the 14 mothers, including the one mother who had two children, seemed to tolerate their pregnancies well, had no special problems at the time of delivery, and feel that their postpartum state of health has not been compromised when compared with their antepartum condition. Thus, although this series is small, it was concluded that potential mothers who were desirous of having a child, and who had had a good clinical result, did have a good chance of a successful pregnancy without putting themselves at substantial risk and that the prior tendency to routinely discourage pregnancy in these women should be re-evaluated. The great majority of our more than 600 patients presently surviving, nearly 90% in recent follow-up surveys, are New York Heart Association class I or class II, capable of full-time school or employment and leading good quality lives. Many are now more than 10 years postoperative and reaching their adulthood years. A recent follow-up survey of our 89 presently surviving Fontan patients who had their procedure performed as adults (age 18 or older) and who could therefore remember well their preoperative status, revealed that 89% of these patients felt the quality of their life had been improved by the surgery, 51% markedly so.
Address correspondence and reprint requests to Douglas D. Mair, MD, Mayo Clinic, 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. Selection 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. Fontan operation in 176 patients with tricuspid atresia: Results and a proposed new index 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 left ventricle: The Mayo Clinic experience. J Am Coll Cardiol 1991;18:1727– 32. 5. De Leval MR, Kilner P, Gewillig M, Bull L. Total cavopulmonary connection: A logical alternative to atriopulmonary connection for complex Fontan 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 operation applicable to patients with left atrioventricular valve atresia or single atrioventricular valve. Circulation 1987;76 (Suppl III):53– 60.
Conclusion Before the Fontan approach was formulated, patients with a functional single ventricle had a natural history characterized by gradually increasing disability secondary to progressive hypoxemia and ventricular myocardial deterioration. In patients who did survive the childhood years, their quality of
7. Bridges ND, Lock JE, Lastaneda AR. Baffle fenestration with subsequent transcatheter closure: Modification of the Fontan operation for patients at increased risk. Circulation 1990;82:1681–9. 8. Cetta F, Feldt RH, O’Leary PW, et al. Improved early morbidity and mortality after Fontan operation: The Mayo Clinic experience, 1987 to 1992. J Am Coll Cardiol 1996;28:2:480 – 6.
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adult populations. These include particular attention to the systemic and pulmonary veins with respect to their inflow patterns and cardiac situs. Subcostal views as well as views from the right chest may be necessary for complete characterization. Transesophageal echocardiography (TEE) obviously will provide incremental information with respect to image quality, and in many instances with respect to diagnostic information. Pertinent points regarding specific congenital lesions follow.
9. Porter CJ, Garson A. Incidence and management of dysrhythmias after Fontan procedure. Herz 1993;18:5:318 –27. 10. Feldt RH, Driscoll DJ, Offord KP, et al. Protein losing enteropathy after the Fontan operation. J Thorac Cardiovasc Surg 1996;112:3:672– 80. 11. Mertens L, Dumoulin M, Gewillig M. Effect of percutaneous fenestration of the atrial septum on protein-losing enteropathy after the Fontan operation. Br Heart J 1994;72:591–2. 12. Canobbio MM, Mair DD, Van Der Velde M, Koos BJ. Pregnancy outcomes after the Fontan repair. J Am Coll Cardiol 1996;28:3:763–7.
ASD The ASD is the most common congenital lesion to escape detection into adulthood. In many instances it is an isolated defect allowing survival into the fourth, fifth and even sixth decades of life with minimal or no symptoms. ASDs result in left to right shunting with a right ventricular (RV) and pulmonary blood flow overload pattern which eventually results in right heart dilation, potentially subsequent pulmonary hypertension and, in its advanced stages, atrial arrhythmias and RV failure. Patients may remain asymptomatic well into the fourth and fifth decades of life even with large atrial septal defects. The three predominant types of ASDs are the secundum ASD, primum ASD and sinus venosus ASD. These can be accurately diagnosed and characterized using echocardiographic techniques. Rarer forms of ASDs, such as the unroofed coronary sinus, can likewise be diagnosed. From an echocardiographic standpoint, the hallmark of an ASD is a RV volume overload pattern with dilation of the right ventricle and flattening of the ventricular septum in diastole. The interventricular septum assumes circular geometry in systole. It should be emphasized that this pattern will be seen in any RV diastolic volume overload including significant tricuspid regurgitation, pulmonic regurgitation or anomalous pulmonary venous return. Using modern transthoracic scanners it is frequently possible to directly visualize the ASD and characterize it as primum, secundum or sinus venosus. The latter is substantially more likely to elude direct visualization than are primum and secundum defects. If a defect is not directly visualized, color-flow Doppler imaging can often give clues as to the presence of an abnormal atrial level shunt and contrast echocardiography can be used to demonstrate right to left shunting. In instances in which an ASD is suspected but not directly visualized, its presence can be confirmed in virtually all instances by TEE. It is most commonly a sinus venosus ASD in which TEE is required to establish the diagnosis. In addition to making the diagnosis and localizing the defect, TEE can be utilized to determine its precise size and the integrity of the atrial septal tissue. This may have particular pertinence in the future as percutaneous closure devices become available. In young individuals in whom an uncomplicated ASD has been detected, echocardiography provides
PERSPECTIVE
Echocardiographic Evaluation of Congenital Heart Disease William F. Armstrong, MD, Echocardiography Laboratory, Division of Cardiology, University of Michigan, Ann Arbor, Michigan Because two-dimensional echocardiography can identify and characterize all four chambers and the great vessels, it is capable of establishing the diagnosis of virtually any form of congenital cardiac disease in both infants and children. Combined with physiologic assessments from color-flow and spectral Doppler imaging, physiologic information can be obtained as well, resulting in a comprehensive and accurate evaluation of congenital heart disease (CHD) which often precludes the necessity for cardiac catheterization for diagnosis. It should be recognized that the spectrum of CHD in adults differs substantially from that seen in infants and children. In pediatric populations more complex lesions have a relative predominance, while in adults simpler lesions such as atrial septal defect (ASD) tend to predominate. The reason for this is a selection over time, in that younger patients with significant CHD are more often detected and repaired in childhood. The most common congenital cardiac lesion to “escape” detection until adulthood is the uncomplicated ASD. There are rarer instances of small ventricular septal defects (VSDs), persistent ductus arteriosus and coarctation of the aorta which likewise escape detection until adulthood. Similarly, the diagnosis of Ebstein’s anomaly may not be made until adulthood. Other lesions, especially those resulting in cyanosis such as tetralogy of Fallot, single ventricle, large ventricular septal defect, etc., are virtually all diagnosed in infancy and childhood. Many of these lesions do not allow survival to adulthood without palliative or corrective surgery. The echocardiographic evaluation of CHD requires specific attention to several parameters not usually evaluated in
Presented in part at an American College of Cardiology Board Review Course, Indianapolis, IN, September 3–7, 1997. Updated in January 1998.
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mitral valve incompetence were not mandatory to achieve a surgical survivor or a good late result. With the passage of time it has become clear that the important criteria that must be met to obtain a good result involve only the size of the pulmonary arteries, the level of the pulmonary arteriolar resistance, and the status of the systolic and diastolic function of the potential patient’s single ventricle. As experience with the procedure increased, institutions with a large and on-going patient population have established and published modifications of the original criteria in these areas and well-recognized guidelines for patient selection now exist (3,4).
UPDATE
The Fontan Procedure: What Have We Learned and Accomplished? Douglas D. Mair, MD, Mayo Clinic and Mayo Foundation, Rochester, Minnesota In 1969 Fontan performed his first pioneering operation on a patient with tricuspid atresia designed to completely separate the systemic and pulmonary circulations and thereby eliminate the systemic arterial hypoxemia and left ventricular volume overload which were the hallmarks of this condition (1). Although this procedure, which subsequently bore his name, was not truly corrective because of its inability to establish a two-ventricle circulation, it was potentially a higher grade of palliation than what had been previously provided through various shunting operations which did not completely separate the two circulations and which often added substantially to the volume load on the single functional left ventricle. It was recognized at the onset, however, that the elevated systemic venous pressures inevitably present in the post-Fontan patient, necessary to propel the blood through the lungs in the absence of a “booster pump” on the right side of the circulation, might lead to late complications in surgical survivors and that functional limitations would likely still exist in these patients, particularly in physical activities requiring a substantial increase in cardiac output. More than 25 years have past since Fontan’s initial procedure, it has undergone many technical modifications, a surgical evolution which still continues, and its use has been expanded and applied to many anatomic types of functional single ventricle in addition to tricuspid atresia. Several thousands of patients around the world have had the procedure and many surgical survivors are now 10 years or more postoperative and are reaching adulthood. Therefore, we are now in a position to assess what has been accomplished by this novel surgical approach; to compare post-Fontan procedure patients’ present state of well-being with the “natural history” of the various forms of functional single ventricle before this operation became available; and to make recommendations regarding its continued application in patients for whom it might potentially provide benefit.
Surgical Techniques Fontan advocated placing caval valves and using a valved right atrium to hypoplastic right ventricle conduit in his surgical patients with tricuspid atresia (1). It subsequently became clear that the caval valves do not function well and deteriorate rapidly and that a hypoplastic right ventricle was not necessary to propel the systemic venous blood into the lungs. An experimental model in the late 1980s (5) demonstrated that flow turbulence and energy losses are reduced when pulsation in a valveless chamber is eliminated and flow pathways are streamlined maximally with elimination of corners. This study proposed total cavopulmonary connections with exclusion of most of the right atrium, a concept which they felt also might reduce the incidence of postoperative atrial dysrhythmias as well as improve hemodynamics. In recent years this concept has gained wide favor and presently, in most major centers, the superior vena cava is anastomosed directly to the pulmonary arteries and inferior vena cava blood is then routed to the pulmonary arteries either via a “lateral tunnel” (6) within the right atrium or via an entirely extracardiac pathway with the medial aspect of this pathway located along the lateral border of the right atrium. The questions of whether to “fenestrate” the inferior vena caval pathway and whether it is necessary to “stage” the Fontan procedure by performing a bi-directional superior vena cava to pulmonary artery anastomosis as a preliminary operation before completing the Fontan circulation by directing inferior vena caval blood directly to the pulmonary arteries as a “second stage” remain controversial (7). Some institutions have favored these approaches in attempting to decrease operative mortality. At the Mayo Clinic, however, we continue to favor the non-fenestrated non-staged approach in low risk surgical candidates, reserving fenestration and/or staging for those patients who present a somewhat increased operative risk secondary to mildly compromised ventricular function, borderline-sized pulmonary arteries, or who may require concomitant atrioventricular valve repair or replacement, or subaortic resection at the time of their Fontan procedure.
Criteria for Operability Choussat and Fontan (2) originally listed “ten anatomic and physiologic commandments” that they felt must be met before this new operative approach could be successfully applied. It subsequently became clear that this list was too stringent and that strict criteria regarding age of patients, presence of sinus rhythm, normal systemic and pulmonary venous drainage, normal right atrial size, and absence of
ACC CURRENT JOURNAL REVIEW May/June 1998 © 1998 by the American College of Cardiology Published by Elsevier Science Inc.
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1062-1458/98/$19.00 PII S1067-1458(98)00030-0
CONGENITAL HEART DISEASE
aggressive treatment such as overdrive pacing or a surgical intervention like the Maze procedure to effectively control. However, the evolution of newer surgical techniques for the Fontan operation such as the “extracardiac Fontan” where the right atrium does not have multiple suture lines and also does not have large portions of its wall exposed to increased wall tension, offer promise for a reduced incidence of troublesome atrial dysrhythmias in future operative survivors. The potential for right heart thromboembolism in the postoperative Fontan patient is of concern because of the non-pulsatile nature of the circulation and the decreased cardiac output these patients may manifest. In the large Mayo Clinic experience, two patients dying some years after surgery demonstrated, at autopsy, large right atrial thrombi with evidence of thrombotic pulmonary emboli as well. Two additional patients operated on early in the series who had a valved conduit used in the right heart reconstruction, a surgical practice long since abandoned, died late as a result of thrombotic conduit occlusion. Postoperative follow-up at our institution routinely involves echo-Doppler examination, one of the purposes of which is to look for right heart thrombi and we have, in a small number of cases, seen laminated thrombi in the right atrium or cavae, but have not, to date, seen a case where it was obstructing the right heart pathways. The decision whether to routinely place the postFontan patient on long-term warfarin anticoagulant therapy because of the potential for thromboembolism remains controversial, but it has not been our policy to do so. Again, with the new surgical techniques which “streamline” the flow of blood through the right heart and decrease the right atrial volume, it is hoped that the potential for thrombus formation may be reduced. With the elevation of systemic venous pressure an inevitable consequence of the Fontan procedure, it had been realized that the potential would exist for the development of protein losing enteropathy, a complication seen previously in patients with constrictive pericarditis and secondarily elevated systemic venous pressures. A recent review from our institution (10) revealed that the risk of development of protein losing enteropathy was 13.4% after 10 years. Although in a significant number of patients it may be mild in degree and not produce clinical manifestations, in others it may be significant and produce varying degrees of hypoalbuminemia with secondary pleural effusions, ascites, etc. Medical therapy with anticongestive measures and albumin infusion may produce improvement in some symptomatic patients. In our experience, the addition of corticosteroids, as advocated by some, has not been beneficial. More recently “fenestration” of the atrial baffle, either surgically or in the catheterization laboratory, which reduces right atrial pressure and increases cardiac output although at the expense of some arterial hypoxemia, has been reported, in some cases, to improve or eliminate protein losing enterop-
Operative and Late Results As improved patient selection criteria and surgical techniques have evolved, and acute perioperative management improved, the operative mortality rate for the Fontan procedure has been dramatically reduced even for the more complex forms of single ventricle. Operative mortality for the non-fenestrated one-stage Fontan procedure at our institution is now ,5% for the lesions of tricuspid atresia and double inlet left ventricle and ,10% for the more complex single ventricle malformations such as those associated with asplenia and polysplenia, pulmonary atresia with intact ventricular septum, and single ventricle of right ventricular morphology (8). The trend in recent times to perform the procedure at a younger age, during the early childhood years, is no doubt also responsible in part for the improved operative results, as such patients whose functional single ventricle has not been subjected to many years of hypoxemia and volume overloading usually do not have significant impairment of systolic or diastolic ventricular function at the time of operation and are less likely to have associated problems such as significant atrioventricular valve regurgitation or subaortic obstruction. With many operative survivors now 10 to 20 years postFontan procedure and reaching adulthood, information is now becoming available regarding the late results of the operation and the quality of life which it affords. At the Mayo Clinic more than 900 Fontan procedures have been performed for the various forms of functional single ventricle. Some late deaths have occurred as a result of reoperation (usually for atrioventricular valve replacement), sudden dysrhythmia, thromboembolism, gradual myocardial deterioration and secondary congestive heart failure, and protein losing enteropathy. A recent review of the 216 patients with tricuspid atresia who had the Fontan procedure at the Mayo Clinic between 1973 and 1996 revealed 26 late deaths among the 197 operative survivors, an incidence of 13%. The deaths occurred between 9 months and 18 years postFontan. Statistical analysis of this group revealed a significantly improved Kaplan-Meier late survival curve for patients operated upon during the most recent decade, again likely a reflection of improving patient selection and generally younger age at the time of operation. Because the Fontan procedure, as originally performed, involved multiple suture lines within the atrium and exposed the right atrium to increased pressure and wall tension after completion, it was recognized that postoperative atrial dysrhythmias might be a concern. Follow-up studies have established that 10 to 20% of patients may have paroxysmal atrial tachycardia or atrial flutter-fibrillation (9). Although such rhythm disturbances are usually amenable to medical therapy with good results, in occasional instances they may be quite refractory to drug therapy, requiring more
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life was usually significantly impaired by adolescence and survival beyond early adulthood was uncommon. The initial 25 year experience with the Fontan operation has been generally gratifying. Well-established selection criteria for potential patients has evolved and for such properly selected patients operative risk is now ,5% in the simple lesions and ,10% in the more complex forms of single ventricle. Although follow-up reveals a significant late mortality and morbidity, surgical advances and the tendency to now perform the operation earlier in life, before serious ventricular impairment has occurred, leads to optimism that these problems will be less prevalent in patients presently undergoing the procedure. Clearly, additional time must pass before firm conclusions can be drawn regarding the benefits of this operative procedure which represents a palliative approach for a group of complex congenital heart disease lesions for which correction is not possible. However, the initial 25 year experience suggests that the Fontan procedure has been a major step forward in providing help and hope to a group of patients with among the most severe forms of congenital heart disease and that children currently undergoing the procedure have an excellent chance of surviving the operation and leading good quality lives into their adult years.
athy (11). Very recently the use of heparin therapy on a periodic basis has been advocated as effective treatment for this complication. On occasion when the patient is refractory to all other measures and is continuing to deteriorate, cardiac transplantation is considered and it has been successful in some patients in reversing this potentially debilitating and fatal complication. A frequently raised question, as many of our female Fontan patients reach adulthood, is the advisability of pregnancy. Pregnancy and eventual delivery place increased demands on the cardiovascular system and these post-Fontan patients have a limited ability to increase their cardiac output. They also have increased venous pressures and a tendency toward fluid retention, factors which are also exacerbated by pregnancy. We have recently surveyed our adult female post-Fontan population in an attempt to determine pregnancy outcomes (12). Although these patients did seem to exhibit an increased incidence (33%) of spontaneous first trimester miscarriage, in those who did not miscarry there were 15 live births from 14 different mothers. Only one child was born significantly prematurely and all 15 infants, including the premature baby, are presently doing well. The only congenital heart disease in the offspring was one secundum atrial septal defect. In addition, all of the 14 mothers, including the one mother who had two children, seemed to tolerate their pregnancies well, had no special problems at the time of delivery, and feel that their postpartum state of health has not been compromised when compared with their antepartum condition. Thus, although this series is small, it was concluded that potential mothers who were desirous of having a child, and who had had a good clinical result, did have a good chance of a successful pregnancy without putting themselves at substantial risk and that the prior tendency to routinely discourage pregnancy in these women should be re-evaluated. The great majority of our more than 600 patients presently surviving, nearly 90% in recent follow-up surveys, are New York Heart Association class I or class II, capable of full-time school or employment and leading good quality lives. Many are now more than 10 years postoperative and reaching their adulthood years. A recent follow-up survey of our 89 presently surviving Fontan patients who had their procedure performed as adults (age 18 or older) and who could therefore remember well their preoperative status, revealed that 89% of these patients felt the quality of their life had been improved by the surgery, 51% markedly so.
Address correspondence and reprint requests to Douglas D. Mair, MD, Mayo Clinic, 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. Selection 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. Fontan operation in 176 patients with tricuspid atresia: Results and a proposed new index 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 left ventricle: The Mayo Clinic experience. J Am Coll Cardiol 1991;18:1727– 32. 5. De Leval MR, Kilner P, Gewillig M, Bull L. Total cavopulmonary connection: A logical alternative to atriopulmonary connection for complex Fontan 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 operation applicable to patients with left atrioventricular valve atresia or single atrioventricular valve. Circulation 1987;76 (Suppl III):53– 60.
Conclusion Before the Fontan approach was formulated, patients with a functional single ventricle had a natural history characterized by gradually increasing disability secondary to progressive hypoxemia and ventricular myocardial deterioration. In patients who did survive the childhood years, their quality of
7. Bridges ND, Lock JE, Lastaneda AR. Baffle fenestration with subsequent transcatheter closure: Modification of the Fontan operation for patients at increased risk. Circulation 1990;82:1681–9. 8. Cetta F, Feldt RH, O’Leary PW, et al. Improved early morbidity and mortality after Fontan operation: The Mayo Clinic experience, 1987 to 1992. J Am Coll Cardiol 1996;28:2:480 – 6.
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adult populations. These include particular attention to the systemic and pulmonary veins with respect to their inflow patterns and cardiac situs. Subcostal views as well as views from the right chest may be necessary for complete characterization. Transesophageal echocardiography (TEE) obviously will provide incremental information with respect to image quality, and in many instances with respect to diagnostic information. Pertinent points regarding specific congenital lesions follow.
9. Porter CJ, Garson A. Incidence and management of dysrhythmias after Fontan procedure. Herz 1993;18:5:318 –27. 10. Feldt RH, Driscoll DJ, Offord KP, et al. Protein losing enteropathy after the Fontan operation. J Thorac Cardiovasc Surg 1996;112:3:672– 80. 11. Mertens L, Dumoulin M, Gewillig M. Effect of percutaneous fenestration of the atrial septum on protein-losing enteropathy after the Fontan operation. Br Heart J 1994;72:591–2. 12. Canobbio MM, Mair DD, Van Der Velde M, Koos BJ. Pregnancy outcomes after the Fontan repair. J Am Coll Cardiol 1996;28:3:763–7.
ASD The ASD is the most common congenital lesion to escape detection into adulthood. In many instances it is an isolated defect allowing survival into the fourth, fifth and even sixth decades of life with minimal or no symptoms. ASDs result in left to right shunting with a right ventricular (RV) and pulmonary blood flow overload pattern which eventually results in right heart dilation, potentially subsequent pulmonary hypertension and, in its advanced stages, atrial arrhythmias and RV failure. Patients may remain asymptomatic well into the fourth and fifth decades of life even with large atrial septal defects. The three predominant types of ASDs are the secundum ASD, primum ASD and sinus venosus ASD. These can be accurately diagnosed and characterized using echocardiographic techniques. Rarer forms of ASDs, such as the unroofed coronary sinus, can likewise be diagnosed. From an echocardiographic standpoint, the hallmark of an ASD is a RV volume overload pattern with dilation of the right ventricle and flattening of the ventricular septum in diastole. The interventricular septum assumes circular geometry in systole. It should be emphasized that this pattern will be seen in any RV diastolic volume overload including significant tricuspid regurgitation, pulmonic regurgitation or anomalous pulmonary venous return. Using modern transthoracic scanners it is frequently possible to directly visualize the ASD and characterize it as primum, secundum or sinus venosus. The latter is substantially more likely to elude direct visualization than are primum and secundum defects. If a defect is not directly visualized, color-flow Doppler imaging can often give clues as to the presence of an abnormal atrial level shunt and contrast echocardiography can be used to demonstrate right to left shunting. In instances in which an ASD is suspected but not directly visualized, its presence can be confirmed in virtually all instances by TEE. It is most commonly a sinus venosus ASD in which TEE is required to establish the diagnosis. In addition to making the diagnosis and localizing the defect, TEE can be utilized to determine its precise size and the integrity of the atrial septal tissue. This may have particular pertinence in the future as percutaneous closure devices become available. In young individuals in whom an uncomplicated ASD has been detected, echocardiography provides
PERSPECTIVE
Echocardiographic Evaluation of Congenital Heart Disease William F. Armstrong, MD, Echocardiography Laboratory, Division of Cardiology, University of Michigan, Ann Arbor, Michigan Because two-dimensional echocardiography can identify and characterize all four chambers and the great vessels, it is capable of establishing the diagnosis of virtually any form of congenital cardiac disease in both infants and children. Combined with physiologic assessments from color-flow and spectral Doppler imaging, physiologic information can be obtained as well, resulting in a comprehensive and accurate evaluation of congenital heart disease (CHD) which often precludes the necessity for cardiac catheterization for diagnosis. It should be recognized that the spectrum of CHD in adults differs substantially from that seen in infants and children. In pediatric populations more complex lesions have a relative predominance, while in adults simpler lesions such as atrial septal defect (ASD) tend to predominate. The reason for this is a selection over time, in that younger patients with significant CHD are more often detected and repaired in childhood. The most common congenital cardiac lesion to “escape” detection until adulthood is the uncomplicated ASD. There are rarer instances of small ventricular septal defects (VSDs), persistent ductus arteriosus and coarctation of the aorta which likewise escape detection until adulthood. Similarly, the diagnosis of Ebstein’s anomaly may not be made until adulthood. Other lesions, especially those resulting in cyanosis such as tetralogy of Fallot, single ventricle, large ventricular septal defect, etc., are virtually all diagnosed in infancy and childhood. Many of these lesions do not allow survival to adulthood without palliative or corrective surgery. The echocardiographic evaluation of CHD requires specific attention to several parameters not usually evaluated in
Presented in part at an American College of Cardiology Board Review Course, Indianapolis, IN, September 3–7, 1997. Updated in January 1998.
ACC CURRENT JOURNAL REVIEW May/June 1998 © 1998 by the American College of Cardiology Published by Elsevier Science Inc.
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