J. MAXWELL CHAMBERLAIN MEMORIAL PAPER
Fontan Procedure for Hypoplastic Left Heart Syndrome William I. Norwood, Jr, MD, PhD, Marshall L. Jacobs, MD, and John D. Murphy, MD The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
Since 1985, 354 neonates have undergone palliative reconstruction for hypoplastic left heart syndrome with 109 early deaths and 12 late deaths. Of the survivors, before 1989,77 patients underwent a subsequent modified Fontan operation, consisting of baffling the atrial septa1 defect to the tricuspid valve (initial 25 patients) or intraatrial baffling of the inferior vena cava to the pulmonary arteries and superior vena cava (52 patients). There were 17 early deaths and three late deaths. Major serous effusions developed in 42 patients (54%) after Fontan operation. Since 1989, a staged approach to Fontan’s operation was undertaken in an effort to reduce the volume load of the right ventricle as early as possible, to minimize the impact of rapid changes in ventricular geometry and diastolic function that can accompany a primary Fontan operation, and to reduce effusive complications. Thus, at a mean age of 6 months, 121patients have undergone closure of aortopulmonary shunt, augmentation of central pulmonary arteries, and association
of the superior vena cava with the branch pulmonary arteries (hemi-Fontan procedure). Of these, 61 patients have already undergone completion of the Fontan procedure with six early deaths and three late deaths. Major serous effusions developed in 28 patients (46%)with the staged Fontan. For perspective, the contemporary experience since January 1991 consists of 58 neonates who have undergone initial palliation with 11 deaths (19%), 17 patients who have undergone the hemi-Fontan procedure with one death (6%), and 21 patients who have undergone completion of the Fontan operation with one death (5%). In conclusion, a total of 138 patients with hypoplastic left heart syndrome have undergone Fontan’s procedure. A two-stage approach to total cavopulmonary connection has not eliminated the transient morbidity of serous effusions but has been associated with a significant improvement in patient survival (p < 0.05).
I
dure shortly after birth. Thus, a standardized surgical approach to HLHS in the neonate has evolved based on initial palliation, which consists of atrial septectomy, transection of the main pulmonary artery, anastomosis of the proximal main pulmonary artery to the diminutive ascending aorta, augmentation of the ascending aorta and entire aortic arch with excision of the contraductal shelf, and construction of a systemic to pulmonary artery shunt. The initial palliative procedure is embodied by three basic principles: (1) the aorta must be associated directly with the right ventricle in a fashion that guarantees unobstructed flow from the right ventricle to the systemic circulation with growth potential obviating a further aortic operation; (2) pulmonary blood flow must be regulated for proper growth and development and maturation of the pulmonary vasculature to avoid the development of pulmonary vascular obstructive disease and to minimize the volume load on the ventricle; and (3) a large interatrial communication is necessary to avoid pulmonary venous hypertension. After initial palliation, the systemic and pulmonary circulations are connected at the arterial level, and the volume work of the single ventricle is equal to the sum of the systemic and pulmonary blood flow. After a period of maturation of the pulmonary vasculature, systemic venous return may be directed to the pulmonary arteries,
n the early 1970s, Fontan and Baudet [l]and Kreutzer and associates [2] independently introduced operative treatment of tricuspid atresia that produced nearly normal oxygen saturation of the systemic circulation and normal volume work for the systemic ventricle. Since that time, the principle of the Fontan operation has been applied to a variety of heart malformations with a single functional ventricle [ 3 ] . At an estimated prevalence of 1 to 4 per 10,000 live births, hypoplastic left heart syndrome (HLHS) is the most common defect with one functional ventricle. It accounts for 7% to 8% of congenital heart disease seen in the first year of life, and it is the most common cause of death due to heart disease in the newborn period [4]. The reconstructive surgical approach to HLHS is based on the principle that carefully planned and appropriately timed palliative operations should result in physiology suitable for repair by a modification of the Fontan procedure. The normally high pulmonary vascular resistance of the neonate precludes the possibility of achieving a cavopulmonary connection, and thus separating the systemic and pulmonary circulations, as a reparative procePresented at the Twenty-eighth Annual Meeting of The Society of Thoracic Surgeons, Orlando, FL, Feb >5, 1992. Address reprint requests to Dr Norwood, The Children‘s Hospital of Philadelphia, 34th Street and Civic Center Blvd, Philadelphia, PA 19104.
0 1992 by The Society of Thoracic Surgeons
(Ann Thorac Surg 2992;54:2025-30)
0003-4975/92/$5.00
1026
C H A ~ I B ~ RAIN I PAPER NOI~WOODET AL FONTAN FOR IIYPOPI A5TIC LEFT HEART
thus placing the systemic and pulmonary circulations in series, reducing the volume work of the right ventricle to the equivalent of the systemic blood flow only and achieving a more normal systemic arterial oxygen saturation. Successful physiologic repair of HLHS by completion of the Fontan operation in a previously palliated infant was first reported by Norwood and associates in 1983 [5]. The purpose of the present study was to analyze the surgical results and clinical outcome for patients with HLHS treated by a staged approach to surgical reconstruction culminating in a modified Fontan procedure. Previous reports from this institution have dealt with the short-term and intermediate-term results of the initial reconstructive operation [6, 71, the hemodynamic assessment after the initial reconstructive operation and its relevance to the modified Fontan procedure [8], and the outcome of a modified Fontan procedure for HLHS as the second and final stage of reconstruction (91. At The Children’s Hospital of Philadelphia, recent efforts to improve the overall outcome of operation for HLHS have included the division of the Fontan procedure into two stages: the hemi-Fontan procedure, wherein the systemic to pulmonary artery shunt is closed and the superior vena cava is associated with the branch pulmonary arteries, and the completion Fontan procedure, wherein the inferior vena cava is associated with the superior vena cava and pulmonary arteries. The specific focus of this study is to evaluate the effect of this two-stage approach to the Fontan operation for HLHS on morbidity and mortality.
Material and Methods Patients The medical records of 138 consecutive patients treated with some modification of the Fontan procedure who initially underwent a reconstructive operation for HI.HS at The Children’s Hospital of Philadelphia between January 1985 and September 1991 were retrospectively reviewed, including echocardiographic records, cardiac catheterization reports, surgical notes, and hospital charts. For purposes of analysis, the patients were divided into two cohorts: those who underwent a primary Fontan operation after initial palliative reconstruction, and those who were managed by a two-staged approach to the Fontan operation (hemi-Fontan followed by completion Fontan). Comparisons of survival after the modified Fontan operation were made between cohorts using Fisher’s exact test [lo].
Operative Technique For the hemi-Fontan procedure, extracorporeal circulation is accomplished by cannulation of the neoaorta and the right atrium. Hypothermic cardiopulmonary bypass is established using a bubble oxygenator with integrated heat exchanger. The polytetrafluoroethylene systemic to pulmonary artery shunt is occluded using metallic clips as soon as bypass has been established. Flow is maintained at approximately 150 mL * kg-’ * min-’ until nasopharyngeal and esophageal temperatures are less than 18°C. The ascending aorta is cross-clamped. The circulation is dis-
Ann Thorac Surg 1992;54:102530
continued, and blood is drained into the oxygenatorreservoir through the venous cannula. A single dose of cold crystalloid cardioplegia solution is infused into the aortic root. The pulmonary arteries are freed from behind the aorta, and a longitudinal incision is made in the anterior aspect of the pulmonary arteries extending from the level of origin of the right upper lobe branch to the level of origin of the left upper lobe branch. An incision is made in the most superior portion of the right atrium and is extended onto the medial aspect of the superior vena cava (Fig 1A). At the most rightward extent of the pulmonary arteriotomy, the right pulmonary artery is anastomosed to the posterior lip of the opened superior vena cava (Fig 1B). A gusset of cryopreserved pulmonary artery homograft is used to augment the confluence of the pulmonary arteries and to create a roof over the patulous anastomosis of the pulmonary arteries to the superior vena cava (Fig 1C). A portion of the same homograft gusset is used as a dam to close the junction of the right atrium with the superior vena cava (Fig 1D). The heart is then recannulated. For the completion Fontan, cannulation and bypass are accomplished in identical fashion. After administration of cardioplegia and during hypothermic circulatory arrest, the lateral wall of the right atrium is opened longitudinally, anterior and parallel to the sulcus terminalis. The incision extends inferiorly to the level of the eustacian valve of the inferior vena cava and superiorly to within a few millimeters of the junction of the right atrium with the superior vena cava. A portion of the pulmonary artery homograft that had been used as a dam to close the right atrium-superior vena cava junction is excised, taking care that the resulting orifice is as large as the inferior vena cava. A gusset of appropriate length is then cut from a portion of a 10-mm polytetrafluoroethylene tube graft that has been opened longitudinally. This is then used to create a lateral atrial tunnel by which inferior vena caval flow is directed to the pulmonary arteries (Fig 2). A portion of the tunnel comprises the free wall of the right atrium. This partitioning of the atrium is fundamentally similar to techniques previously described by de Leva1 [ll],Puga [12], Norwood [13], and others. After closure of the atriotomy incision, reperfusion and rewarming and separation from bypass are accomplished. Catheters are inserted for the postoperative measurement of pressures within the atrium and the systemic venous pathway.
Results and Comment From January 1985 to September 1991, 354 neonates underwent initial palliative reconstruction for HLHS at The Children’s Hospital of Philadelphia, with 109 early deaths and 12 late deaths. A systematic review of the outcome of initial palliation was reported in 1990 by Murdison and associates [14]. The early (less than 30 days) mortality rate was 33.5%. Analysis revealed that survival was related neither to the anatomical subtype of HLHS nor to the type of aortopulmonary shunt that was constructed. One third of all deaths occurred due to cardiovascular collapse during the first postoperative day.
CHAMBERLAINPAPER NORWOOD ET AL FONTAN FOR HYPOPLASTIC LEFT HEART
Ann Thorac Surg 1992;X 1025-30
1027
B
C
D
Fig 1 . The hemi-Fontan procedure: (A) A longitudinal incision is made in the anterior aspect of the pulmona ry arteries extending from the level of origin of the right upper lobe branch to the level of origin of the left upper lobe branch. An incision is made in the most superior portion of the right atrium and is extended onto the medial aspect of the superior vena cava. ( B ) At the most rightward extent of the pulmonary arteriotomy, the right pulmonary artery is anastomosed to the posterior lip of the opened superior vena cava. (C) A gusset of cryopreserved pulmonary artery homograft is used to augment the confluence of the pulmonary arteries and to create a roof over the patulous anastomosis of the pulmonary arteries to the superior vena cava. (D)A portion of the same homograft gusset is used as a dam to close the junction of the right atrium with the superior vena cava. The shaded arrow indicates the path of flow of blood from the superior vena cava into the right and left pulmonary arteries.
Analysis of this early mortality suggested that successful postoperative management depends on the maintenance of a critical balance between systemic and pulmonary blood flow. This flow ratio is related directly to the ratio of systemic and pulmonary vascular resistances. It appears that carbon dioxide has a potent and relatively independent influence on pulmonary vascular resistance, making possible some clinical control over this physiology by manipulation of the degree of mechanical ventilation. Recently, the initial postoperative management has been modified to include the routine addition of carbon dioxide to the inspired gas mixture [15, 161. This allows more
precise control of the relative resistances in the systemic and pulmonary vascular beds, while maintaining normal minute ventilation, and has virtually eliminated cardiovascular collapse in the very early postoperative period. Thus, from January to September 1991, 58 neonates underwent initial palliation with 11 deaths (mortality, 19%). The staged approach to reconstructive operation for HLHS is directed toward eventual separation of the systemic and pulmonary circulations by the application of the Fontan procedure. Before 1989, 77 survivors of initial palliation underwent a subsequent modified Fontan operation. In the initial 25 patients, the procedure included
1028
CHAMBERLAIN PAPER NORWOOD ET AL FONTAN FOR HYPOPLASTIC LEFT HEART
A
Ann Thorac Surg 1992;54:102530
B
Fig 2. The completion Fontan procedure: (A) The completed cavopulmonay connection. After excision of the portion of pulmonary artery homograft that was used as a dam to close the right atrium-superior vena cava junction, the inferior uena cava is associated with the confluence of the superior vena caua and pulmona y arteries by atrial partitioning, which is accomplished with a gusset of polytetrafluoroethylene. ( B ) A single frame of a cineangiogram of the systemic venous pathway obtained during follow-up cardiac catheterization after completion Fontan procedure. (LPA = left pulmonary artery; RA = the systemic venous pathway through the partitioned right atrium; RPA = right pulmonary artery.)
baffling of the atrial septa1 defect to the tricuspid valve, and in the subsequent 52 patients, intraatrial baffling of the inferior vena cava to the pulmonary arteries and superior vena cava. The patients ranged in age from 5 months to 6 years (median age, 19 months). There were 17 early deaths and three late deaths. A detailed review of this series of patients was reported recently by Farrell and associates [8]. There were no detectable differences in intermediate survival rates after a modified Fontan procedure among the anatomic subtypes of HLHS. Chang and colleagues [9] from this institution previously reported their evaluation of the relation of preoperative hemodynamic parameters to the outcome of a modified Fontan procedure in patients with HLHS. They analyzed preoperative ”risk factors” including elevated pulmonary artery pressure (mean pulmonary artery pressure >15 mm Hg), elevated pulmonary vascular resistance (>4 U * m2), elevated ventricular end-diastolic pressure (>12 mm Hg), pulmonary artery distortion, and tricuspid regurgitation of moderate or severe degree. There was no statistical difference in percent mortality for any of these factors, although there was a trend toward poorer outcome in the presence of moderate or severe tricuspid regurgitation. This did not achieve statistical significance, as the number of patients with moderate or severe tricuspid regurgitation (n = 7) was small. Analysis of preoperative hemodynamics does not predict which patients are at risk for ventricular dysfunction and death after a Fontan procedure. It is nonetheless true that in some patients, an unpredictable and rapid decrease in ventricular diastolic volume accompanies closure of the systemic to pulmo-
nary artery shunt and diversion of systemic venous blood to the pulmonary arteries, and this is associated with marked changes in ventricular geometry that result in markedly diminished ventricular compliance, elevated atrial and pulmonary artery pressures, low cardiac output, tachycardia, and eventual death. Cardiac catheterization of survivors of the Fontan procedure for HLHS has revealed excellent function of the right ventricle as the systemic ventricle [8].Nonetheless, a high percentage of patients experienced postoperative morbidity related to the occurrence of serous effusions. Forty-two of the 77 patients (54%) who underwent a primary Fontan procedure after initial palliation had development of major pleural or pericardial effusions or ascites. Since 1989, a staged approach l o the Fontan operation was undertaken in an effort to reduce the volume load of the right ventricle as early as possible, to minimize the impact of rapid changes in ventricular geometry and diastolic function that can accompany a primary Fontan operation, and to reduce effusive complications. Thus, at a mean age of 6 months, 121 patients have undergone a hemi-Fontan procedure [17]. This comprises closure of the systemic to pulmonary artery shunt, augmentation of the central pulmonary arteries, and association of the superior vena cava with the branch pulmonary arteries. The pattern of blood flow achieved after a hemi-Fontan operation is essentially the same as that achieved by a more conventional ”bidirectional” Glenn procedure. We believe that certain technical features of the hemi-Fontan operation make it a more logical step in the process of
Ann Thorac Surg 1992;54.1025-30
achieving eventual completion of t h e Fontan procedure. First, it includes the elimination of any areas of stenosis or distortion of the branch pulmonary arteries and their confluence. Second, t h e normal relation of t h e superior vena cava t o t h e right atrium is preserved, considerably simplifying the eventual completion of the Fontan procedure and obviating the need for reestablishing t h e connection of the superior vena cava to the right atrium. Instead, a portion of the homograft dam is merely excised, leaving a widely p a t e n t o p e n i n g between the right atrium and the confluence of the superior vena cava w i t h the p u l m o n a r y arteries. Between August 1989 a n d September 1991, 61 patients have undergone completion of the Fontan operation after a previous hemi-Fontan procedure. There h a v e been six early d e a t h s and three late deaths. This represents a significant i m p r o v e m e n t i n patient survival ( p < 0.05). Once again, serous effusions represent the most prevalent morbid complication i n this group of patients. Major serous effusions developed i n 28 of 61 patients after t h e staged Fontan procedure. The majority of the 52 survivors (follow-up period, 1m o n t h to 25 m o n t h s ) w e r e described by their cardiologists as d o i n g well from both a cardiovascular and a developmental standpoint. The oldest girl w e a r s glasses, captains the kickball team, and receives A’s and Bs i n standard fifth-grade class. Approximately two thirds of the children (35 patients) take no medications. The remainder take digoxin alone o r i n combination with a diuretic. One patient has had recurrent supraventricular tachyarrhythmias. One patient u n d e r w e n t pacemaker implantation for temporary atrioventricular dissociation but i s now i n normal s i n u s rhythm.
Conc1usions So far, a total of 138 patients w i t h HLHS h a v e undergone the Fontan procedure. Cardiac catheterization of survivors reveals excellent function of the right ventricle as the systemic ventricle. A two-stage approach to t h e Fontan operation, i n c l u d i n g a hemi-Fontan p r o c e d u r e a t 6 m o n t h s of age followed by completion Fontan procedure a t 12 to 18 months, has n o t eliminated the transient morbidity of serous effusions, b u t has been associated w i t h a significant i m p r o v e m e n t i n patient survival ( p
Fontan Procedure for Hypoplastic Left Heart Syndrome William I. Norwood, Jr, MD, PhD, Marshall L. Jacobs, MD, and John D. Murphy, MD The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
Since 1985, 354 neonates have undergone palliative reconstruction for hypoplastic left heart syndrome with 109 early deaths and 12 late deaths. Of the survivors, before 1989,77 patients underwent a subsequent modified Fontan operation, consisting of baffling the atrial septa1 defect to the tricuspid valve (initial 25 patients) or intraatrial baffling of the inferior vena cava to the pulmonary arteries and superior vena cava (52 patients). There were 17 early deaths and three late deaths. Major serous effusions developed in 42 patients (54%) after Fontan operation. Since 1989, a staged approach to Fontan’s operation was undertaken in an effort to reduce the volume load of the right ventricle as early as possible, to minimize the impact of rapid changes in ventricular geometry and diastolic function that can accompany a primary Fontan operation, and to reduce effusive complications. Thus, at a mean age of 6 months, 121patients have undergone closure of aortopulmonary shunt, augmentation of central pulmonary arteries, and association
of the superior vena cava with the branch pulmonary arteries (hemi-Fontan procedure). Of these, 61 patients have already undergone completion of the Fontan procedure with six early deaths and three late deaths. Major serous effusions developed in 28 patients (46%)with the staged Fontan. For perspective, the contemporary experience since January 1991 consists of 58 neonates who have undergone initial palliation with 11 deaths (19%), 17 patients who have undergone the hemi-Fontan procedure with one death (6%), and 21 patients who have undergone completion of the Fontan operation with one death (5%). In conclusion, a total of 138 patients with hypoplastic left heart syndrome have undergone Fontan’s procedure. A two-stage approach to total cavopulmonary connection has not eliminated the transient morbidity of serous effusions but has been associated with a significant improvement in patient survival (p < 0.05).
I
dure shortly after birth. Thus, a standardized surgical approach to HLHS in the neonate has evolved based on initial palliation, which consists of atrial septectomy, transection of the main pulmonary artery, anastomosis of the proximal main pulmonary artery to the diminutive ascending aorta, augmentation of the ascending aorta and entire aortic arch with excision of the contraductal shelf, and construction of a systemic to pulmonary artery shunt. The initial palliative procedure is embodied by three basic principles: (1) the aorta must be associated directly with the right ventricle in a fashion that guarantees unobstructed flow from the right ventricle to the systemic circulation with growth potential obviating a further aortic operation; (2) pulmonary blood flow must be regulated for proper growth and development and maturation of the pulmonary vasculature to avoid the development of pulmonary vascular obstructive disease and to minimize the volume load on the ventricle; and (3) a large interatrial communication is necessary to avoid pulmonary venous hypertension. After initial palliation, the systemic and pulmonary circulations are connected at the arterial level, and the volume work of the single ventricle is equal to the sum of the systemic and pulmonary blood flow. After a period of maturation of the pulmonary vasculature, systemic venous return may be directed to the pulmonary arteries,
n the early 1970s, Fontan and Baudet [l]and Kreutzer and associates [2] independently introduced operative treatment of tricuspid atresia that produced nearly normal oxygen saturation of the systemic circulation and normal volume work for the systemic ventricle. Since that time, the principle of the Fontan operation has been applied to a variety of heart malformations with a single functional ventricle [ 3 ] . At an estimated prevalence of 1 to 4 per 10,000 live births, hypoplastic left heart syndrome (HLHS) is the most common defect with one functional ventricle. It accounts for 7% to 8% of congenital heart disease seen in the first year of life, and it is the most common cause of death due to heart disease in the newborn period [4]. The reconstructive surgical approach to HLHS is based on the principle that carefully planned and appropriately timed palliative operations should result in physiology suitable for repair by a modification of the Fontan procedure. The normally high pulmonary vascular resistance of the neonate precludes the possibility of achieving a cavopulmonary connection, and thus separating the systemic and pulmonary circulations, as a reparative procePresented at the Twenty-eighth Annual Meeting of The Society of Thoracic Surgeons, Orlando, FL, Feb >5, 1992. Address reprint requests to Dr Norwood, The Children‘s Hospital of Philadelphia, 34th Street and Civic Center Blvd, Philadelphia, PA 19104.
0 1992 by The Society of Thoracic Surgeons
(Ann Thorac Surg 2992;54:2025-30)
0003-4975/92/$5.00
1026
C H A ~ I B ~ RAIN I PAPER NOI~WOODET AL FONTAN FOR IIYPOPI A5TIC LEFT HEART
thus placing the systemic and pulmonary circulations in series, reducing the volume work of the right ventricle to the equivalent of the systemic blood flow only and achieving a more normal systemic arterial oxygen saturation. Successful physiologic repair of HLHS by completion of the Fontan operation in a previously palliated infant was first reported by Norwood and associates in 1983 [5]. The purpose of the present study was to analyze the surgical results and clinical outcome for patients with HLHS treated by a staged approach to surgical reconstruction culminating in a modified Fontan procedure. Previous reports from this institution have dealt with the short-term and intermediate-term results of the initial reconstructive operation [6, 71, the hemodynamic assessment after the initial reconstructive operation and its relevance to the modified Fontan procedure [8], and the outcome of a modified Fontan procedure for HLHS as the second and final stage of reconstruction (91. At The Children’s Hospital of Philadelphia, recent efforts to improve the overall outcome of operation for HLHS have included the division of the Fontan procedure into two stages: the hemi-Fontan procedure, wherein the systemic to pulmonary artery shunt is closed and the superior vena cava is associated with the branch pulmonary arteries, and the completion Fontan procedure, wherein the inferior vena cava is associated with the superior vena cava and pulmonary arteries. The specific focus of this study is to evaluate the effect of this two-stage approach to the Fontan operation for HLHS on morbidity and mortality.
Material and Methods Patients The medical records of 138 consecutive patients treated with some modification of the Fontan procedure who initially underwent a reconstructive operation for HI.HS at The Children’s Hospital of Philadelphia between January 1985 and September 1991 were retrospectively reviewed, including echocardiographic records, cardiac catheterization reports, surgical notes, and hospital charts. For purposes of analysis, the patients were divided into two cohorts: those who underwent a primary Fontan operation after initial palliative reconstruction, and those who were managed by a two-staged approach to the Fontan operation (hemi-Fontan followed by completion Fontan). Comparisons of survival after the modified Fontan operation were made between cohorts using Fisher’s exact test [lo].
Operative Technique For the hemi-Fontan procedure, extracorporeal circulation is accomplished by cannulation of the neoaorta and the right atrium. Hypothermic cardiopulmonary bypass is established using a bubble oxygenator with integrated heat exchanger. The polytetrafluoroethylene systemic to pulmonary artery shunt is occluded using metallic clips as soon as bypass has been established. Flow is maintained at approximately 150 mL * kg-’ * min-’ until nasopharyngeal and esophageal temperatures are less than 18°C. The ascending aorta is cross-clamped. The circulation is dis-
Ann Thorac Surg 1992;54:102530
continued, and blood is drained into the oxygenatorreservoir through the venous cannula. A single dose of cold crystalloid cardioplegia solution is infused into the aortic root. The pulmonary arteries are freed from behind the aorta, and a longitudinal incision is made in the anterior aspect of the pulmonary arteries extending from the level of origin of the right upper lobe branch to the level of origin of the left upper lobe branch. An incision is made in the most superior portion of the right atrium and is extended onto the medial aspect of the superior vena cava (Fig 1A). At the most rightward extent of the pulmonary arteriotomy, the right pulmonary artery is anastomosed to the posterior lip of the opened superior vena cava (Fig 1B). A gusset of cryopreserved pulmonary artery homograft is used to augment the confluence of the pulmonary arteries and to create a roof over the patulous anastomosis of the pulmonary arteries to the superior vena cava (Fig 1C). A portion of the same homograft gusset is used as a dam to close the junction of the right atrium with the superior vena cava (Fig 1D). The heart is then recannulated. For the completion Fontan, cannulation and bypass are accomplished in identical fashion. After administration of cardioplegia and during hypothermic circulatory arrest, the lateral wall of the right atrium is opened longitudinally, anterior and parallel to the sulcus terminalis. The incision extends inferiorly to the level of the eustacian valve of the inferior vena cava and superiorly to within a few millimeters of the junction of the right atrium with the superior vena cava. A portion of the pulmonary artery homograft that had been used as a dam to close the right atrium-superior vena cava junction is excised, taking care that the resulting orifice is as large as the inferior vena cava. A gusset of appropriate length is then cut from a portion of a 10-mm polytetrafluoroethylene tube graft that has been opened longitudinally. This is then used to create a lateral atrial tunnel by which inferior vena caval flow is directed to the pulmonary arteries (Fig 2). A portion of the tunnel comprises the free wall of the right atrium. This partitioning of the atrium is fundamentally similar to techniques previously described by de Leva1 [ll],Puga [12], Norwood [13], and others. After closure of the atriotomy incision, reperfusion and rewarming and separation from bypass are accomplished. Catheters are inserted for the postoperative measurement of pressures within the atrium and the systemic venous pathway.
Results and Comment From January 1985 to September 1991, 354 neonates underwent initial palliative reconstruction for HLHS at The Children’s Hospital of Philadelphia, with 109 early deaths and 12 late deaths. A systematic review of the outcome of initial palliation was reported in 1990 by Murdison and associates [14]. The early (less than 30 days) mortality rate was 33.5%. Analysis revealed that survival was related neither to the anatomical subtype of HLHS nor to the type of aortopulmonary shunt that was constructed. One third of all deaths occurred due to cardiovascular collapse during the first postoperative day.
CHAMBERLAINPAPER NORWOOD ET AL FONTAN FOR HYPOPLASTIC LEFT HEART
Ann Thorac Surg 1992;X 1025-30
1027
B
C
D
Fig 1 . The hemi-Fontan procedure: (A) A longitudinal incision is made in the anterior aspect of the pulmona ry arteries extending from the level of origin of the right upper lobe branch to the level of origin of the left upper lobe branch. An incision is made in the most superior portion of the right atrium and is extended onto the medial aspect of the superior vena cava. ( B ) At the most rightward extent of the pulmonary arteriotomy, the right pulmonary artery is anastomosed to the posterior lip of the opened superior vena cava. (C) A gusset of cryopreserved pulmonary artery homograft is used to augment the confluence of the pulmonary arteries and to create a roof over the patulous anastomosis of the pulmonary arteries to the superior vena cava. (D)A portion of the same homograft gusset is used as a dam to close the junction of the right atrium with the superior vena cava. The shaded arrow indicates the path of flow of blood from the superior vena cava into the right and left pulmonary arteries.
Analysis of this early mortality suggested that successful postoperative management depends on the maintenance of a critical balance between systemic and pulmonary blood flow. This flow ratio is related directly to the ratio of systemic and pulmonary vascular resistances. It appears that carbon dioxide has a potent and relatively independent influence on pulmonary vascular resistance, making possible some clinical control over this physiology by manipulation of the degree of mechanical ventilation. Recently, the initial postoperative management has been modified to include the routine addition of carbon dioxide to the inspired gas mixture [15, 161. This allows more
precise control of the relative resistances in the systemic and pulmonary vascular beds, while maintaining normal minute ventilation, and has virtually eliminated cardiovascular collapse in the very early postoperative period. Thus, from January to September 1991, 58 neonates underwent initial palliation with 11 deaths (mortality, 19%). The staged approach to reconstructive operation for HLHS is directed toward eventual separation of the systemic and pulmonary circulations by the application of the Fontan procedure. Before 1989, 77 survivors of initial palliation underwent a subsequent modified Fontan operation. In the initial 25 patients, the procedure included
1028
CHAMBERLAIN PAPER NORWOOD ET AL FONTAN FOR HYPOPLASTIC LEFT HEART
A
Ann Thorac Surg 1992;54:102530
B
Fig 2. The completion Fontan procedure: (A) The completed cavopulmonay connection. After excision of the portion of pulmonary artery homograft that was used as a dam to close the right atrium-superior vena cava junction, the inferior uena cava is associated with the confluence of the superior vena caua and pulmona y arteries by atrial partitioning, which is accomplished with a gusset of polytetrafluoroethylene. ( B ) A single frame of a cineangiogram of the systemic venous pathway obtained during follow-up cardiac catheterization after completion Fontan procedure. (LPA = left pulmonary artery; RA = the systemic venous pathway through the partitioned right atrium; RPA = right pulmonary artery.)
baffling of the atrial septa1 defect to the tricuspid valve, and in the subsequent 52 patients, intraatrial baffling of the inferior vena cava to the pulmonary arteries and superior vena cava. The patients ranged in age from 5 months to 6 years (median age, 19 months). There were 17 early deaths and three late deaths. A detailed review of this series of patients was reported recently by Farrell and associates [8]. There were no detectable differences in intermediate survival rates after a modified Fontan procedure among the anatomic subtypes of HLHS. Chang and colleagues [9] from this institution previously reported their evaluation of the relation of preoperative hemodynamic parameters to the outcome of a modified Fontan procedure in patients with HLHS. They analyzed preoperative ”risk factors” including elevated pulmonary artery pressure (mean pulmonary artery pressure >15 mm Hg), elevated pulmonary vascular resistance (>4 U * m2), elevated ventricular end-diastolic pressure (>12 mm Hg), pulmonary artery distortion, and tricuspid regurgitation of moderate or severe degree. There was no statistical difference in percent mortality for any of these factors, although there was a trend toward poorer outcome in the presence of moderate or severe tricuspid regurgitation. This did not achieve statistical significance, as the number of patients with moderate or severe tricuspid regurgitation (n = 7) was small. Analysis of preoperative hemodynamics does not predict which patients are at risk for ventricular dysfunction and death after a Fontan procedure. It is nonetheless true that in some patients, an unpredictable and rapid decrease in ventricular diastolic volume accompanies closure of the systemic to pulmo-
nary artery shunt and diversion of systemic venous blood to the pulmonary arteries, and this is associated with marked changes in ventricular geometry that result in markedly diminished ventricular compliance, elevated atrial and pulmonary artery pressures, low cardiac output, tachycardia, and eventual death. Cardiac catheterization of survivors of the Fontan procedure for HLHS has revealed excellent function of the right ventricle as the systemic ventricle [8].Nonetheless, a high percentage of patients experienced postoperative morbidity related to the occurrence of serous effusions. Forty-two of the 77 patients (54%) who underwent a primary Fontan procedure after initial palliation had development of major pleural or pericardial effusions or ascites. Since 1989, a staged approach l o the Fontan operation was undertaken in an effort to reduce the volume load of the right ventricle as early as possible, to minimize the impact of rapid changes in ventricular geometry and diastolic function that can accompany a primary Fontan operation, and to reduce effusive complications. Thus, at a mean age of 6 months, 121 patients have undergone a hemi-Fontan procedure [17]. This comprises closure of the systemic to pulmonary artery shunt, augmentation of the central pulmonary arteries, and association of the superior vena cava with the branch pulmonary arteries. The pattern of blood flow achieved after a hemi-Fontan operation is essentially the same as that achieved by a more conventional ”bidirectional” Glenn procedure. We believe that certain technical features of the hemi-Fontan operation make it a more logical step in the process of
Ann Thorac Surg 1992;54.1025-30
achieving eventual completion of t h e Fontan procedure. First, it includes the elimination of any areas of stenosis or distortion of the branch pulmonary arteries and their confluence. Second, t h e normal relation of t h e superior vena cava t o t h e right atrium is preserved, considerably simplifying the eventual completion of the Fontan procedure and obviating the need for reestablishing t h e connection of the superior vena cava to the right atrium. Instead, a portion of the homograft dam is merely excised, leaving a widely p a t e n t o p e n i n g between the right atrium and the confluence of the superior vena cava w i t h the p u l m o n a r y arteries. Between August 1989 a n d September 1991, 61 patients have undergone completion of the Fontan operation after a previous hemi-Fontan procedure. There h a v e been six early d e a t h s and three late deaths. This represents a significant i m p r o v e m e n t i n patient survival ( p < 0.05). Once again, serous effusions represent the most prevalent morbid complication i n this group of patients. Major serous effusions developed i n 28 of 61 patients after t h e staged Fontan procedure. The majority of the 52 survivors (follow-up period, 1m o n t h to 25 m o n t h s ) w e r e described by their cardiologists as d o i n g well from both a cardiovascular and a developmental standpoint. The oldest girl w e a r s glasses, captains the kickball team, and receives A’s and Bs i n standard fifth-grade class. Approximately two thirds of the children (35 patients) take no medications. The remainder take digoxin alone o r i n combination with a diuretic. One patient has had recurrent supraventricular tachyarrhythmias. One patient u n d e r w e n t pacemaker implantation for temporary atrioventricular dissociation but i s now i n normal s i n u s rhythm.
Conc1usions So far, a total of 138 patients w i t h HLHS h a v e undergone the Fontan procedure. Cardiac catheterization of survivors reveals excellent function of the right ventricle as the systemic ventricle. A two-stage approach to t h e Fontan operation, i n c l u d i n g a hemi-Fontan p r o c e d u r e a t 6 m o n t h s of age followed by completion Fontan procedure a t 12 to 18 months, has n o t eliminated the transient morbidity of serous effusions, b u t has been associated w i t h a significant i m p r o v e m e n t i n patient survival ( p
