Improving outcomes of the Fontan operation in children with atrial isomerism and heterotaxy syndromes.

BACKGROUND: The historic outcome of the Fontan procedure in children with single ventricle and heterotaxy syndrome has been poor, and in the current era it has been incompletely described. METHODS: From January 1993 through April 2000, 30 patients (age range, 5.3 +/- 3.6 years) had total cavopulmonary connection for single ventricle and isomerism and heterotaxy syndrome. Right atrial isomerism and heterotaxy (n = 19) or left atrial isomerism and heterotaxy (n = 11) were associated with a morphologic right ventricle (n = 26), a common atrioventricular valve (n = 25), pulmonary atresia (n = 9) or stenosis (n = 17), anomalous pulmonary venous drainage (partial, n = 7; total, n = 11; obstructed, n = 4), and interrupted inferior vena cava (n = 13). A previous systemic to pulmonary artery shunt had been performed in 21 patients, and 3 patients had previous pulmonary artery banding. The Fontan procedure was staged in all but 3 patients at a median age of 12 months (range, 3 to 114 months). Before the Fontan procedure, atrial arrhythmia was present in 7 patients (23%). RESULTS: An extracardiac conduit was constructed in 22 patients (median diameter, 20 mm; range, 16 to 27 mm), and a lateral tunnel was constructed in 4 patients. Associated procedures included pulmonary artery augmentation (n = 17), repair of anomalous pulmonary venous drainage (n = 7), and repair of a regurgitant atrioventricular valve (n = 2). The mean cardiopulmonary bypass time was 134 +/- 57 minutes. Cardioplegic cardiac arrest was used in 12 patients for a mean duration of 62 +/- 28 minutes. There were four hospital deaths (13%), three that occurred in children having concomitant repair of anomalous pulmonary venous drainage (previously undetected in one). Thirteen children (41%) developed early postoperative atrial arrhythmias, 11 of the 13 children required temporary pacing. There was one late death. Follow-up (3.4 +/- 2.7 years) was available on 24 of 25 survivors. All but 2 patients were in sinus rhythm. CONCLUSIONS: Early and midterm outcomes after the Fontan procedure in this patient group improved and may be further ameliorated by detecting and repairing associated obstruction to pulmonary venous flow and performing atrioventricular valvuloplasty before the Fontan procedure.

Evolving strategies and improving outcomes of the modified norwood procedure: a 10-year single-institution experience.

BACKGROUND: This study reviews our 10-year experience with the modified Norwood procedure to determine its early and midterm outcomes. The focus is on the impact of evolving management strategies and accumulated institutional experience. METHODS: A modified Norwood operation was performed in 171 infants over a 10-year period. Sixty-eight percent of the infants were male, the median age at operation was 6 days (range 1 to 175 days), and the median weight was 3.3 kg (range 1.7 to 4.8 kg). The 10-year period was divided into three eras: era I; 1990 through 1993; era II; 1994 through 1997; and era III; 1998 into 2000. Outcomes and risk factors for mortality were sought. RESULTS: Hypoplastic left heart syndrome or a variant was the primary diagnosis in 118 infants (69%). The overall 5-year survival rate was 43%. Multivariate analysis revealed that only need of preoperative ventilatory support, earlier date of operation, and lower weight at operation were significant independent predictors of increased time-related mortality. Morphologic features such as a diagnosis other than hypoplastic left heart syndrome, ascending aortic size, and noncardiac anomalies were not significantly associated with an increased risk of death. The hospital survival rate for stage-one palliation in era III was 82%, significantly better than that in the preceding eras (p < 0.001). Attrition between stages one and two accounted for a 15% mortality rate among hospital survivors. CONCLUSIONS: With increasing experience and improvements in perioperative care and surgical technique, good outcomes can be expected for the first-stage modified Norwood procedure. Greater monitoring of patients in the interstage period may reduce interval mortality and improve overall survival.

Echocardiographic assessment of obstructive lesions in atrioventricular septal defects.

OBJECTIVES: We sought to determine the accuracy of transthoracic echocardiography (TTE) in identifying risk factors in patients with an atrioventricular septal defect (AVSD). BACKGROUND: Atrioventricular septal defect is a common lesion, and many decisions about it are based on echocardiography alone. The identification of associated left-sided inflow and outflow obstructive lesions is important, as they are responsible for mortality and morbidity. METHODS: Between 1983 to 1998, 549 patients with AVSD underwent repair. The TTE findings were correlated with surgery, angiocardiography, autopsy or postoperative TTE. Papillary muscle measurements were made in those with either a left ventricular outflow tract (LVOT) or left ventricular inflow abnormality and compared with those measurements from control subjects. Measurements of the LVOT were made in patients with an identified LVOT abnormality. RESULTS: There were 63 missed lesions, decreasing over time. Double-orifice left atrioventricular valve (DOLAVV) and nonobstructive chordae in the LVOT were more often missed. Reoperation was performed to address a missed lesion in 2 of 68 patients. Two of 55 patients died of reasons related to a missed lesion. In 67% of patients, DOLAVV was missed. Abnormal papillary muscle angles were seen with either a LVOT abnormality or DOLAVV. High insertion of the anterolateral papillary muscle was a risk factor for death or residual LVOT obstruction. Abnormal LVOT measurements were found in patients with tunnel obstruction and those with an acquired subaortic ridge. CONCLUSIONS: Transthoracic echocardiography provides accurate preoperative information on AVSD.

Pediatric heart transplantation: improving results in high-risk patients.

Our institutional experience with 68 pediatric patients undergoing cardiac transplantation was reviewed to determine the impact of unconventional donor and recipient management protocols implemented to extend the availability of this therapy. The introduction of donor blood insulin cardioplegia was associated with a significant improvement in patient and graft survival. Among 63 ABO-matched transplant procedures, both the patient and graft loss rate were significantly lower (by multivariable analysis) with the use of the donor blood insulin cardioplegia versus conventional cardioplegia, despite significantly longer ischemic times in the former group. Twenty-three (33.8%) patients were deemed at ultra-high risk: eight of 11 patients with cardiomyopathy transplanted following ECMO support survived without major sequelae; three of four additional patients survived early retransplantation. Ten patients underwent intentional ABO-incompatible transplantation under a protocol of plasma exchange on bypass. There were two early deaths because of nonspecific graft failure and respiratory complications with mild vascular rejection, and one late death because of lymphoma. Among seven surviving ABO-incompatible patients followed up to 31 months, there have been no episodes of humoral rejection despite development of antidonor blood group antibodies in A to O, but not B to O, mismatches. The results with pediatric cardiac transplantation continue to improve as a result of changes in both surgical and medical protocols permitting salvage of patients conventionally considered at high risk or nontransplantable.

Total cavopulmonary connections in children with a previous Norwood procedure.

BACKGROUND: Outcomes of the Fontan operation in children initially palliated with the modified Norwood procedure are incompletely defined. METHODS: From August 1993 to January 2000, 45 patients (mean age 2.6 +/- 1.1 years, weight 12.7 +/- 2.8 kg) who were palliated with staged Norwood procedures (hypoplastic left heart syndrome, n = 32; nonhypoplastic left heart syndrome, n = 13) underwent a modified Fontan operation. Preoperative features included moderate/severe atrioventricular valve regurgitation (n = 5, 11%), reduced ventricular function on echocardiography in 11 patients, McGoon index 1.56 +/- 0.38, and pulmonary artery distortion in 18 patients (40%). RESULTS: A lateral tunnel (n = 16) or an extracardiac conduit (n = 29) connection with fenestration in 38 patients (84%) was used. Concomitant procedures included pulmonary artery reconstruction (n = 24, 53%), atrioventricular valve repair (n = 4, 9%) or replacement (n = 1). Before Fontan, 12 patients (27%) had an intervention to address neoaortic obstruction, and 7 patients required balloon dilation/stenting of the left (n = 5) or right pulmonary artery (n = 5). Intraoperatively, left (n = 5) or right pulmonary artery (n = 1) stenting was performed in 5 patients (11%). On follow-up, 8 patients required additional interventional procedures to address left pulmonary artery narrowing (n = 5), or venous (n = 5) or arteriopulmonary collaterals (n = 1). Perioperative mortality was 4.4% (n = 2). There were 2 late deaths at a mean follow-up of 39 +/- 20 months. CONCLUSIONS: In relatively high-risk patients, midterm results of the Fontan operation for children initially palliated with the Norwood procedure were good. Combined interventional-surgical treatment algorithms can lead to improved outcomes.

ABO-incompatible heart transplantation in infants.

BACKGROUND: Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens. METHODS: We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors. RESULTS: The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donor's blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent. CONCLUSIONS: ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Pediatric heart transplantation: improving results in high-risk patients.

OBJECTIVES: Our institutional experience with 73 pediatric patients undergoing cardiac transplantation between January 1, 1990, and December 31, 1999, was reviewed to determine the impact of unconventional donor and recipient management protocols implemented to extend the availability of this therapy. METHODS AND RESULTS: The introduction of donor blood cardioplegic solution with added insulin was associated with a significant improvement in patient and graft survival (hazard ratio [Cox] = 0.25, P =.08), despite significantly longer ischemic times with this protocol compared with the use of crystalloid-based donor procurement techniques (P <.01). Eleven patients underwent intentional transplantation of ABO-incompatible donor hearts with the aid of a protocol of plasma exchange on bypass. In this subgroup, there were 2 early deaths caused by nonspecific graft failure (n = 1) and respiratory complications with mild vascular rejection (n = 1), and there was 1 late death caused by lymphoma. ABO-incompatible transplantation was not a risk factor for death by multivariate analysis. The postoperative course in these patients suggests minimal reactivity directed against incompatible grafts on the basis of low anti-donor blood group antibody production, in association with a favorable rejection profile. Ten of 13 patients requiring preoperative support with an extracorporeal membrane oxygenator survived transplantation; there were 3 additional late deaths in this subgroup (hazard ratio = 2.88, P =.05). CONCLUSIONS: The results with pediatric cardiac transplantation continue to improve as a result of changes in both surgical and medical protocols permitting successful treatment of patients conventionally considered at high risk or unsuitable for transplantation.

Independent factors associated with longevity of prosthetic pulmonary valves and valved conduits.

OBJECTIVE: To evaluate the age dependence of variables predictive of pulmonary valve prosthesis replacement, we conducted the following analysis. METHODS: Retrospective analysis of 945 operations in 726 patients undergoing placement of pulmonary valve prostheses was performed. Age was identified as a strong independent predictor of valve failure. The database was stratified into age-based subsets and predictors of valve replacement were identified within each subset. RESULTS: For the entire cohort, freedom from valve replacement at 5 years was 81%. Younger age was strongly associated with decreased time to valve replacement by multivariable analysis (hazard ratio: 0.71/log-year, P <.001). Other independent factors included diagnosis, type of prosthesis, and time-dependent requirement for pulmonary valve stent placement. Important predictors of valve failure varied among age groups and are as follows: for Age Less Than 3 Months: valve type; for Age 3 Months To Less Than 2 Years: smaller normalized valve prosthesis size; for Age 2 Years To Less Than 13 Years: sex, smaller normalized valve prosthesis size, placement of endovascular stents, and valve type; for Age 13 Years To 65 Years: smaller normalized valve prosthesis size, placement of endovascular stents, and increased number of previous valve placements. CONCLUSION: Age is a dominant risk factor predictive of pulmonary valve prosthesis failure. A significant interaction exists between age and the effects of diagnosis, valve type, and size on prosthetic pulmonary valve longevity.

What is the optimal age for repair of tetralogy of Fallot?

BACKGROUND: Controversy regarding the timing for the repair of tetralogy of Fallot centers around initial palliation versus primary repair for the symptomatic neonate/young infant and the optimal age for repair of the asymptomatic child. We changed our approach from one of initial palliation in the infant to one of primary repair around the age of 6 months, or earlier if clinically indicated. We examined the effects of this change in protocol and age on outcomes. METHODS AND RESULTS: The records of 227 consecutive children who had repair of isolated tetralogy of Fallot from January 1993 to June 1998 were reviewed. The median age of repair by year fell from 17 to 8 months (P:<0.01). The presence of a palliative shunt at the time of repair decreased from 38% to 0% (P:<0.01). Mortality (6 deaths, 2. 6%) improved with time (P:=0.02), with no mortality since the change in protocol (late 1995/early 1996). Multivariate analysis for physiological outcomes of time to lactate clearance, ventilation hours, and length of stay, but not death, demonstrated that an age <3 months was independently associated with prolongation of times (P:<0.03). Each of the deaths occurred with primary repair at an age >12 months. The best survival and physiological outcomes were achieved with primary repair in children aged 3 to 11 months. CONCLUSIONS: On the basis of mortality and physiological outcomes, the optimal age for elective repair of tetralogy of Fallot is 3 to 11 months of age.

Selection of viable cardiomyocytes for cell transplantation using three-dimensional tissue culture.

BACKGROUND: We developed a three-dimensional cardiac tissue culture system to select viable and contractile cells for the purpose of cardiomyocyte transplantation. In this study we will show that reaggregation of cardiomyocytes in culture is an active process indicative of cardiomyocyte viability and functionality. METHODS: Myocardial tissue from newborn mice has been enzymatically digested, incubated in culture inserts, and studied by phase contrast microscopy, conventional histology, immunohistochemistry, electron microscopy, and TUNEL assay. RESULTS: Cells that are plated on nonadhesive surfaces, reaggregate to spontaneously contracting cell aggregates. The capacity to reaggregate was significantly dependent from the age of the tissue donor (P<0.0001) and on the method of enzymatic dissociation (P<0.0001). The majority of cells within the aggregates consisted of cardiomyocytes. After 24 hr incubation, significant amounts of laminin and fibronectin had been deposited between the cells. Ultrastructural analysis revealed viable cardiomyocytes attached to each other by tight junctions. The apoptotic rate within the aggregates was 11.4+/-4.6 vs. 44.5+/-10.5% immediately after dissociation (P<0.05). CONCLUSIONS: The capacity to form spontaneously contracting aggregates is an inherent characteristic of viable cardiomyocytes in 3-dimensional cultures, which could be successfully exploited for cellular cardiomyocyte transplantation.

Are bilateral superior vena cavae a risk factor for single ventricle palliation?

BACKGROUND: Performing superior vena cava-to-pulmonary artery anastomosis, in the presence of bilateral superior vena cavae, can be technically challenging. Our clinical observation has been that bilateral superior vena cavae are a risk factor for poor outcome in children needing single ventricle palliation. METHODS: Detailed operative, angiographic, and follow-up data were analyzed in 39 children undergoing bilateral cavopulmonary anastomosis (b-CPA). Overall outcome was compared to 274 children having a unilateral cavopulmonary anastomoses (u-CPA). RESULTS: Nine patients (23%) with bilateral superior vena cavae were found to have thrombus in the cavopulmonary circulation after the b-CPA. Postoperative mean arterial oxygen saturation was significantly lower in those who had thrombus [69%+/-10% versus 82%+/-7%, (p < 0.01)]. Thrombus formation was associated with mortality. The indexed superior vena cavae size was not a risk factor for thrombosis. In follow-up studies the connecting pulmonary artery segment between the two cavopulmonary anastomosis was smaller than the pulmonary arteries adjacent to the hilum. Survivors of a b-CPA were less frequently converted to a Fontan circulation at 5 years of follow up (Kaplan-Meier 5-year estimates, 39% for b-CPA versus 74% for u-CPA [p = 0.02]). CONCLUSIONS: Bilateral superior vena cava-to-pulmonary artery anastomosis is associated with an increased risk of thrombus formation and unfavorable growth in the central pulmonary arteries. Modifications of surgical technique may alter flow patterns, thereby optimizing growth and diminishing the risk of thrombus formation. Anticoagulation therapy may be an important adjunct in children undergoing a b-CPA.

Pediatric utilization of rapamycin for severe cardiac allograft rejection.

BACKGROUND: Rapamycin is a new immunosuppressive agent that has been shown to be effective in the treatment of acute cardiac rejection in the adult population. METHODS: This case documents a pediatric patient with ongoing cardiac rejection that did not abate despite treatment with antithymocyte serum (RATS), corticosteroid pulses, and methotrexate in addition to daily prednisone, mycophenolate mofetil, and tacrolimus. RESULTS: Initiation of therapy with rapamycin resulted in a rapid resolution of cardiac rejection and reduction of concomitant immunosuppressive agents and few side effects. CONCLUSIONS: This case illustrated the utilization of rapamycin in a pediatric patient with ongoing acute rejection despite several modifications in treatment.

Outcomes for children with cardiomyopathy awaiting transplantation.

OBJECTIVE: To determine factors associated with outcomes after listing for transplantation in children with cardiomyopathies. BACKGROUND: Childhood cardiomyopathies form a heterogeneous group of diseases, and in many, the prognosis is poor, irrespective of the etiology. When profound heart failure develops, cardiac transplantation can be the only viable option for survival. METHODS: We included all children with cardiomyopathy listed for transplantation between 12/89 and 4/98 in this historical cohort study. RESULTS: We listed 31 patients, 15 male and 16 female, 27 with dilated and 4 with restrictive cardiomyopathy, for transplantation. The median age at listing was 5.7 years, with a range from fetal life to 17.8 years. Transplantation was achieved in 23 (74%), with a median interval from listing of 54 days, and a range from zero to 11.4 years. Of the patients, 14 were transplanted within 30 days of listing. Five patients (16%) died before transplantation. Within the Canadian algorithm, one of these was in the third state, and four in the fourth state. One patient was removed from the list after 12 days, having recovered from myocarditis, and two remain waiting transplantation after intervals of 121 and 476 days, respectively. Patients who died were more likely to be female (5/5 vs. 11/26; p=0.04) and to have been in the third or fourth states at listing (5/5 vs. 15/26; p=0.04). The use of mechanical ventricular assistance, in 10 patients, was not a predictor of an adverse outcome. While not statistically significant, survival to transplantation was associated with treatment using inhibitors of angiotensin converting enzyme, less mitral regurgitation, a higher mean ejection fraction and cardiac index, and lower right ventricular systolic pressure. CONCLUSIONS: Children with cardiomyopathy awaiting transplantation have a mortality of 16% related to their clinical state at the time of listing.

A novel repair for patients with atrioventricular septal defect requiring reoperation for left atrioventricular valve regurgitation.

OBJECTIVE: Left atrioventricular valve regurgitation (LAVVR) is the most frequent indication for reoperation following atrioventricular septal defect (AVSD) repair. We estimate from our experience that within 10 years of initial repair, 14% of patients undergoing repair of atrioventricular septal defect (AVSD) require reoperation for this complication. We have developed a novel leaflet augmentation technique for LAVVR which may avoid failure of conventional repair and/or the need for valve replacement. METHOD: The novel technique consists of insertion of a glutaraldehyde-treated autologous pericardial patch to augment the bridging leaflets of the atrioventricular valve. We describe the outcome of eight patients in whom this technique was used and compared them to 68 other patients with AVSD undergoing reoperation for LAVVR by either conventional repair (n=54) or valve replacement (n=14). RESULTS: There were no early deaths or major complications following patch repair. The mean follow-up is 2.3 years (range 1-8.5 years) during which there were no late deaths. Two patients underwent reintervention at 3.5 and 5 years after patch repair for LAVVR and were successfully rerepaired. Mild residual LAVVR was seen at last echocardiography in six patients and mild to moderate in two. These results compare favorably with the 68 patients who underwent conventional surgery. The 3-year freedom from reoperation was 86% for both repair groups. Dysplastic valve tissue appears to be a major risk factor for failure of conventional repair or for valve replacement. Failure of conventional valve repair led to valve replacement in six of seven patients. CONCLUSIONS: For patients with late LAVVR after AVSD repair, pericardial leaflet augmentation is durable and may avoid failure of conventional repair or valve replacement in patients with dysplastic valves.