The first multicentre study on coronary anomalies in the Netherlands: MuSCAT.

BACKGROUND: Current guidelines on coronary anomalies are primarily based on expert consensus and a limited number of trials. A gold standard for diagnosis and a consensus on the treatment strategy in this patient group are lacking, especially for patients with an anomalous origin of a coronary artery from the opposite sinus of Valsalva (ACAOS) with an interarterial course. AIM: To provide evidence-substantiated recommendations for diagnostic work-up, treatment and follow-up of patients with anomalous coronary arteries. METHODS: A clinical care pathway for patients with ACAOS was established by six Dutch centres. Prospectively included patients undergo work-up according to protocol using computed tomography (CT) angiography, ischaemia detection, echocardiography and coronary angiography with intracoronary measurements to assess anatomical and physiological characteristics of the ACAOS. Surgical and functional follow-up results are evaluated by CT angiography, ischaemia detection and a quality-of-life questionnaire. Patient inclusion for the first multicentre study on coronary anomalies in the Netherlands started in 2020 and will continue for at least 3 years with a minimum of 2 years of follow-up. For patients with a right or left coronary artery originating from the pulmonary artery and coronary arteriovenous fistulas a registry is maintained. RESULTS: Primary outcomes are: (cardiac) death, myocardial ischaemia attributable to the ACAOS, re-intervention after surgery and intervention after initially conservative treatment. The influence of work-up examinations on treatment choice is also evaluated. CONCLUSIONS: Structural evidence for the appropriate management of patients with coronary anomalies, especially (interarterial) ACAOS, is lacking. By means of a structured care pathway in a multicentre setting, we aim to provide an evidence-based strategy for the diagnostic evaluation and treatment of this patient group.

Two decades of aortic coarctation treatment in children; evaluating techniques.

OBJECTIVE: This study focuses on the evolution of treatment techniques for aortic coarctation in children and assesses long-term morbidity. METHODS: This retrospective cohort study evaluates patients treated for native aortic coarctation, with at least 7 years of follow-up. To assess time-related changes, three time periods were distinguished according to year of primary intervention (era 1, 2 and 3). Operative and long-term follow-up data were collected by patient record reviews. RESULTS: The study population consisted of 206 patients (177 surgical and 29 catheter-based interventions), with a median follow-up of 151 months. Anterior approach with simultaneous repair of aortic arch and associated cardiac lesions was more common in the most recent era. Median age at intervention did not change over time. Reintervention was necessary in one third of the cohort with an event-free survival of 74% at 5­year and 68% at 10-year follow-up. Reintervention rates were significantly higher after catheter-based interventions compared with surgical interventions (hazard ratio [HR] 1.8, 95% confidence interval [CI] 1.04-3.00, p = 0.04) and in patients treated before 3 months of age (HR 2.1, 95% CI 1.27-3.55, p = 0.003). Hypertension was present in one out of five patients. CONCLUSION: Nowadays, complex patients with associated cardiac defects and arch hypoplasia are being treated surgically on bypass, whereas catheter-based intervention is introduced for non-complex patients. Reintervention is common and more frequent after catheter-based intervention and in surgery under 3 months of age. One fifth of the 206 patients remained hypertensive.

Improving surgical outcome following the Norwood procedure.

BACKGROUND: The Norwood procedure consists of three palliative operations, performed in neonates with hypoplastic left heart syndrome. Especially the first stage (Norwood I) is associated with the highest mortality rates in paediatric cardiac surgery (up to 25%). During surgery, the aorta is reconstructed and a systemic-to-pulmonary shunt is applied. Originally the modified Blalock-Taussig shunt was used, but recently the right-ventricle-to-pulmonary-artery shunt is increasingly being employed. We reviewed the results of our operative strategy, where an individualised choice of shunt is made. Furthermore, attempts to reduce interstage mortality (between Norwood I and II) were assessed. METHODS: All neonates who underwent Norwood stage I palliation from August 2004 until November 2010 were included in this retrospective analysis. Mortality rates and management strategies were compared. RESULTS: Thirty-six patients were available for analysis. Overall 30-day mortality was 5.6% (2 patients) and interstage mortality after discharge was 14% (5 patients). In 2006, a novel clinical protocol was introduced, aimed at reduction of mortality during the interstage period. This resulted in reduction of interstage mortality from 23% to 9% (3 of 13 infants, versus 2 of 23), with a cumulative survival of 82% (maximum follow-up 4 years). CONCLUSION: Early surgical results following the Norwood procedure using an individualised shunt choice are favourable.

Cardiac output can be measured with the transpulmonary thermodilution method in a paediatric animal model with a left-to-right shunt.

BACKGROUND: The transpulmonary thermodilution (TPTD) technique for measuring cardiac output (CO) has never been validated in the presence of a left-to-right shunt. METHODS: In this experimental, paediatric animal model, nine lambs with a surgically constructed aorta-pulmonary left-to-right shunt were studied under various haemodynamic conditions. CO was measured with closed and open shunt using the TPTD technique (CO(TPTD)) with central venous injections of ice-cold saline. An ultrasound transit time perivascular flow probe around the main pulmonary artery served as the standard reference measurement (CO(MPA)). RESULTS: Seven lambs were eligible for further analysis. Mean (sd) weight was 6.6 (1.6) kg. The mean CO(MPA) was 1.21 litre min(-1) (range 0.61-2.06 l min(-1)) with closed shunt and 0.93 litre min(-1) (range 0.48-1.45 litre min(-1)) with open shunt. The open shunt resulted in a mean Q(p)/Q(s) ratio of 1.8 (range 1.6-2.4). The bias between the two CO methods was 0.17 litre min(-1) [limits of agreement (LOA) of 0.27 litre min(-1)] with closed shunt and 0.14 litre min(-1) (LOA of 0.32 litre min(-1)) with open shunt. The percentage errors were 22% with closed shunt and 34% with open shunt. The correlation (r) between the two methods was 0.93 (P<0.001) with closed shunt and 0.86 (P<0.001) with open shunt. The correlation (r) between the two methods in tracking changes in CO (ΔCO) during the whole experiment was 0.94 (P<0.0001). CONCLUSIONS: The TPTD technique is a feasible method of measuring CO in paediatric animals with a left-to-right shunt.

[Favourable results with surgical treatment in 43 children with hypoplastic left-heart syndrome or similar disorders, 1999-2005]. / Gunstige resultaten van chirurgische behandeling van 43 kinderen met het hypoplastisch linkerhartsyndroom of een equivalente afwijking, 1999/'05.

OBJECTIVE: To describe the results of surgical treatment of hypoplastic left-heart syndrome (HLHS) and HLHS-like disorders in the Amsterdam-Leiden Centre for Congenital Heart Disease, the Netherlands. DESIGN: Retrospective, descriptive. METHOD: Data were collected on 43 neonates with HLHS or similar disorders who underwent surgical treatment between December 1999 and December 2005. HLHS was present in 37 patients and 6 had disorders similar to HLHS (unbalanced atrioventricular septal defect, truncus arteriosus with hypoplastic left ventricle, double inlet left ventricle). Surgery was performed in 3 steps: Norwood operation shortly after birth (n = 43), bidirectional cavopulmonary anastomosis a few months later (n = 30) and total cavopulmonary connection at the age of 2-3 years (n = 10). During the Norwood operation, the first 21 patients received a modified Blalock shunt (between the right brachiocephalic artery and pulmonary artery), whereas the following 22 patients received a Sano shunt (between the right ventricle and pulmonary artery). RESULTS: Of the 43 patients, 11 died: 7 within 30 days of the first operation, 2 between the first and second operation, and 2 between the second and third operation. Actuarial survival for the entire group is 74% (32/43). The mortality rate was lower with the Sano shunt (9%; 2/22) than with the modified Blalock shunt (43%; 9/21). Catheter interventions were necessary in 10 patients: 6 had balloon dilatation of the distal aortic arch and 4 had balloon dilatation/stent placement for narrowed pulmonary arteries. With a median follow-up of 22 months (range: 1-75), 2 patients had marked neurological side effects. All 32 surviving patients were in good clinical condition.

[Complete atrioventricular septal defect in children with Down's syndrome: good results of surgical correction at younger and younger ages]. / Compleet atrioventriculair septumdefect bij kinderen met het syndroom van Down: goede resultaten van chirurgische correctie op steeds jongere leeftijd.

OBJECTIVE: To evaluate the results of cardiosurgical treatment of children with Down's syndrome and a complete atrioventricular septal defect (cAVSD). DESIGN: Retrospective. METHOD: Data were collected from the records of all patients with Down's syndrome who had been subjected to primary corrective surgery for cAVSD in the period 1980-2003 in Leiden, The Netherlands. Exclusion criteria were: concomitant tetralogy of Fallot or interruption of the aortic arch and palliative banding of the pulmonary artery. Children with an abnormal shape of the ventricle making it impossible to correct biventricularly were not considered in the study. Data on mortality >30 days after the operation and on repeated surgery were included in the analysis if the duration of follow-up was at least 5 years. RESULTS: The group comprised 148 children: 75 girls and 73 boys. The median age at time of surgery was 20 weeks (range: 6 weeks to 3.7 years) and showed a statistically significant decrease during the period under investigation. Of 4 children lost to clinical follow-up actual data could be obtained. The median duration offollow-up was 6 years and 7 months (range: 38 days to 23 years and 11 months). 28 children (19%) died. The mortality within 30 days after the operation decreased from 0-38% in the period 1980-1989 via 0-30% in the period 1990-1999 to 0% in 2000-2003. The percentage ofreoperations related to the correction ofcAVSD (14%; 14/98) did not seem to increase. Of the correction-related reoperations, 14% (2/14) were followed by a second reoperation. Conclusion. In the period 1980-2003, children with Down's syndrome and a cAVSD were corrected surgically at a younger and younger age. The early mortality decreased to 0% in the years 2000-2003. Echocardiography in the first weeks of life for all children with Down's syndrome makes it possible to diagnose those with a cAVSD early enough for surgical repair.

Biventricular systolic function in young lambs subject to chronic systemic right ventricular pressure overload.

In various clinical situations of congenital heart disease, the right ventricle (RV) is subject to a chronic systemic pressure overload which affects biventricular function and may progress to the development of RV failure. Young lambs (2-3 wk old) underwent adjustable pulmonary artery banding (PAB) at systemic (aortic) level for 8 wk. Biventricular function was determined by using load-independent indexes of global ventricular contractile performance by the end-systolic pressure-volume relationship (ESPVR) using the conductance catheter at baseline and during dobutamine infusion. PAB resulted in a significant fivefold increase in RV end-systolic pressure (12-64 mmHg) and a doubling of the RV-to-left ventricular (LV) wall thickness ratio (P < 0.01). RV global contractile performance increased significantly, as indicated by an increased slope of the ESPVR. Compared with age-matched control lambs, cardiac output decreased from 2.6 to 1.6 l/min (P < 0.05) whereas heart rates were equal. In contrast with RV volume, LV volume decreased significantly after PAB (P < 0.01), whereas the LV-ESPVR slope was unchanged. In the PAB group, the RV, but not the LV, showed a reduced response to dobutamine. We concluded that chronic RV pressure overload for 8 wk results in diminished pump function despite compensatory increased RV global contractile performance.

Acute renal insufficiency and renal replacement therapy after pediatric cardiopulmonary bypass surgery.

The aim of the study was to investigate renal function and renal replacement therapy after cardiopulmonary bypass surgery in children. Patient characteristics (sex, age, diagnosis), operation type, and death were listed. The study was performed retrospectively using serum creatinine level before, and peak values after, cardiopulmonary bypass surgery for assessment of renal function. Of the children on renal replacement therapy, indication, efficacy, and complications were recorded. In a 5-year period, 1075 children had cardiopulmonary bypass surgery at the Department of Cardiothoracic Surgery at Leiden University Medical Center and Academic Medical Center of Amsterdam. One-hundred eighty (17%) patients developed acute renal insufficiency. Twenty-five (2.3%) patients required renal replacement therapy. Peritoneal dialysis is a safe and effective treatment for children after cardiopulmonary bypass surgery. However, 15 (60%) of 25 children on renal replacement therapy died of nonrenal causes. In 9 out of 10 surviving children, renal function was normal at time of discharge from hospital. Acute renal insufficiency is a frequent complication after open-heart surgery, although renal replacement therapy was infrequently necessary. Peritoneal dialysis is a safe and effective therapeutic measure for children after cardiac bypass surgery.

Pulmonary valve insertion late after repair of Fallot's tetralogy.

OBJECTIVES: To analyze the results of pulmonary valve insertion late after initial repair of Fallot's tetralogy. Pulmonary insufficiency (PI) after correction of Fallot's tetralogy is usually well tolerated in the short term, but is associated with symptomatic right ventricular dilatation and an increased risk of ventricular arrhythmias over longer periods of time. METHODS: From 1993 to July 2000, 51 patients were reoperated for PI at a mean age of 25.7+/-11.9 years. The mean age at initial repair was 6.4+/-7.2 years. Patients with a conduit inserted at initial operation, with absent pulmonary valve syndrome or with a more than moderate ventricular septal defect at reoperation were excluded from the study. A cryopreserved pulmonary (96%) or aortic (4%) homograft was implanted in the orthotopic position with the use of cardiopulmonary bypass 19.3+/-9.1 years (2.7-40.3 years) after initial correction. Preoperative symptoms (New York Heart Association, NYHA class), degree of PI (echo-Doppler, MRI), right ventricular dimensions (MRI) and QRS duration were compared to findings at last follow-up. RESULTS: Follow-up is complete and had a mean duration of 1.7+/-1.4 years. Hospital mortality was 2%. No serious morbidity occurred. Severe PI was present preoperatively in all patients. At last follow-up echo-Doppler studies showed PI to be absent or trivial in 96% and mild in 4% of patients. In 13 patients MRI studies were performed both pre- and postoperatively: in this group PI was reduced from a mean of 48 to 4%. After 6 months NYHA capacity class had improved significantly from 2.3+/-0.6 to 1.4+/-0.5. After 1 year end-diastolic and end-systolic right ventricular volumes were reduced significantly. Right ventricular ejection fraction and QRS duration remained unchanged. CONCLUSIONS: PI late after correction of Fallot's tetralogy may lead to serious symptomatic right ventricle dilatation. After pulmonary homograft insertion right ventricular dimensions decrease rapidly and functional improvement is observed in almost all patients.

Implantation of cardioverter device in young children: the perirenal approach.

Placement of Implantable cardioverter devices in young children is complicated because of the relatively large size and heavy weight of these devices. A technique is described where the device is implanted in the left perirenal space while an endovascular lead is used instead of an epicardial patch electrode.

Outcome and follow-up of aortic valve replacement with the freestyle stentless bioprosthesis.

BACKGROUND: The aim of this study was to determine the morbidity, mortality, and hemodynamics after implantation of the Freestyle stentless bioprosthesis in the aortic position. METHODS: A total of 280 patients were operated on from June 1993 to July 1999 as part of a multicenter investigation. Factors influencing hospital mortality and long-term survival were assessed by logistic regression and Cox proportional hazards analysis. Patients were evaluated postoperatively at discharge, at 3 to 6 months, and yearly by clinical examination and color flow Doppler echocardiography. RESULTS: Hospital mortality in this group was relatively high (9.6%). Logistic regression analysis showed that cross-clamp time, age, myocardial infarction, diabetes, left ventricular hypertrophy, coronary artery disease, New York Heart Association class III or IV and female gender were the independent predictive factors. According to the Kaplan-Meier method, the 4-year survival for hospital survivors was 94%. In the multivariate Cox proportional hazard analysis, only coronary artery disease proved to be prognostic. During follow-up, 11 patients developed paravalvular leakage due to prosthetic dehiscence at the side of the noncoronary cusp. Performance of the prosthesis as assessed by echocardiography was excellent. Mean gradient decreased significantly between discharge and follow-up at 3 to 6 months. At 1-year follow-up trivial regurgitation was found in 6 patients (3%) and mild regurgitation in 4 (2%). Regurgitation did not increase with time. The effective orifice area increased significantly from discharge to follow-up at 3 to 6 months. CONCLUSIONS: Hospital mortality after implantation of a stentless bioprosthesis was higher compared to conventional prosthesis. A high incidence of prosthesis dehiscence at the proximal suture line was found, which was probably due to technique. Hemodynamic performance up to 3 years showed low transvalvular gradients. There is echocardiographic evidence for reduction of left ventricular hypertrophy and improvement of left ventricular function.

Remodeling of the porcine pulmonary autograft wall in the aortic position.

OBJECTIVE: Dilatation and valve regurgitation are disturbing sequelae of the pulmonary root functioning at systemic pressures. We tried to characterize the histologic mode of adaptation of the neoaortic wall. METHODS: We compared routine histologic studies, immunohistochemical staining, and computer-assisted morphometric analysis of aortic, pulmonary autograft, and native pulmonary wall specimens from pigs in which, as a newborn, a valveless pulmonary autograft had been implanted in the aorta. RESULTS: Histologic examination of the pulmonary autograft revealed a viable, normally revascularized wall without degenerative phenomena. Smooth muscle cells were enlarged and rearranged. The characteristic "pulmonary" medial elastin lamellar structure was retained, which was confirmed by morphometry. Immunohistochemistry of the autograft revealed relatively strong staining of type III collagen and alpha smooth muscle actin, exclusive staining of basic fibroblast growth factor, and no staining of proliferation markers proliferating cell nuclear antigen and Ki67. CONCLUSION: The developing pulmonary autograft in the aortic position becomes normally revascularized, lacks major degenerative phenomena, and retains its own typical pulmonary morphologic features. Remodeling is accomplished by increased extracellular matrix deposition with collagen as an important constituent. The marked expression of growth factors in the autograft suggests the persistence of increased metabolic activity.

Spin echo MRI in the evaluation of hearts with a double outlet right ventricle: usefulness and limitations.

The surgical approach to a double outlet right ventricle (DORV) is dependent on the spatial relationship of the semilunar valves, outflow tracts and ventricular septal defect (VSD). The purpose of the study was to assess the value of MRI for the evaluation of cardiovascular anatomy in patients before and after surgery for DORV. Spin echo MRI was performed in 12 patients with DORV (eight preoperative and four postoperative patients). Thin-section MRI was performed in three orthogonal planes and selected angulated views were obtained. Conventional imaging by color Doppler echocardiography and cine-angiocardiography and surgical findings, when present, served as the reference standards. The results found that the spatial relationship between semilunar valves and VSD was accurately assessed by MRI in eight out of eight preoperative patients. In the four postoperative cases MRI depicted the morphology of both outflow tracts and provided adequate information on their patency. Of the eight preoperative patients, five have undergone corrective surgery and the MRI findings were confirmed. MRI provided additional information to conventional imaging preoperatively in three cases in which the VSD opened into the outlet portion of the DORV, without there being a direct relation to a semilunar valve. In two preoperative cases in which the VSD was directly committed to the aorta, conventional imaging was conclusive. MRI was unable to depict aberrant chordae tendineae in four out of four cases. We conclude that MRI provides accurate additional anatomic information in patients with DORV, which is helpful in presurgical planning as well as during follow-up. Spin echo MRI does not visualize aberrant chordae tendineae.

Brom's three-patch technique for repair of supravalvular aortic stenosis.

OBJECTIVE: Case histories of all patients (n = 29) operated on for supravalvular aortic stenosis from 1962 to the present were reviewed to study different techniques and outcomes. The technique of symmetric aortoplasty with 3 patches (1 in each sinus) is described and compared with other methods. METHODS: Case reports were reviewed and follow-up was completed by contacting the patient's (pediatric) cardiologist. We aimed for a last follow-up visit, including Doppler echocardiographic studies, in a period no more than 12 months earlier than December 1997. Supravalvular aortic stenosis was discrete in 25 and diffuse with involvement of the aortic arch and arch vessels in 4 patients. Additional anomalies were bicuspid aortic valve (n = 5), coarctation (n = 3), ascending aortic aneurysm (n = 1), mitral valve insufficiency (n = 2), pulmonary valvular stenosis (n = 1), and peripheral pulmonary artery stenosis (n = 2). Eleven patients had Williams syndrome and 1 patient had Noonan syndrome. Symmetric aortoplasty with 3 patches (1 in each sinus) was used in 13 patients, whereas other nonsymmetric methods (1, 2, or Y-shaped patches) were used in 16 patients. Mean follow-up was 10.5 years (range: 4 months-36 years). RESULTS: All techniques adequately decreased the pressure gradient. Progression of preoperative aortic valve insufficiency or de novo regurgitation was not observed except in 1 patient in whom the patches inserted were too large. CONCLUSIONS: No difference could be demonstrated in outcome for any surgical technique; however, reconstruction of the aortic root with autologous pericardial patches in each sinus after transection of the aorta has the advantage of symmetry while restoring the normal aortic root anatomy.

Dehiscence of the Freestyle stentless bioprosthesis.

This study aimed to identify and characterize patients who developed prosthetic dehiscence after aortic valve replacement with the Freestyle Stentless bioprosthesis. Review of patients' records and preoperative echocardiogram was performed. Prosthetic dehiscence developed in 10 patients after 2.5 to 49 months (mean 19). Most patients were symptomatic at presentation. Nine patients were reoperated. Dehiscence was typically located at the inflow suture line beneath the noncoronary cusp. Four patients died. The cause of dehiscence is assumed to be related primarily to surgical technique.

Short-term follow up of the Ross operation in children.

BACKGROUND AND AIMS OF THE STUDY: Aortic valve disease in the pediatric population poses special problems to surgeons and cardiologists. The pulmonary autograft has proven to be a good alternative for aortic valve replacement and left ventricular outflow tract (LVOT) reconstruction in this special group. METHODS: Forty-one children (mean age 10.0 +/- 4.8 (SD) years; range: 35 days to 18.8 years) underwent aortic root replacement with a pulmonary autograft between February 1994 and April 1998. Twenty-one patients (51%) had previous cardiac surgery; seven (17%) had balloon valvulotomy. Aortic root replacement was combined with other techniques for various disorders, including tunnel LVOT obstruction, ventricular septal defect (VSD)-aortic insufficiency complex, neoaortic insufficiency following arterial switch procedure, and subvalvular stenosis following correction of type B interruption of the aortic arch (IAA) with VSD (IAA-B/VSD). RESULTS: The mean follow up was 1.7 +/- 1.0 years (range 44 days to 4.1 years). Total follow up time was 67.8 patient-years. Two patients, both after repair of interrupted aortic arch, died intraoperatively (4.9%). There was no late mortality. Two patients were reoperated on (5.1%), one for autograft insufficiency due to cuspal perforation and one for right ventricular outflow tract stenosis at the distal anastomosis. Thirty-eight patients (97%) are currently in NYHA class I; one child with a preoperatively poor left ventricular function did not improve and is in class II. At the latest echocardiographic follow up, neoaortic regurgitation was absent in 19% of patients, trivial in 69% and mild in 11%. Homograft insufficiency was absent in 64%, trivial in 31% and mild in 6%. All mean gradients for both autograft and homograft were < 15 mmHg. CONCLUSIONS: The Ross operation can be performed with good results in infants and children with different forms of LVOT obstruction and aortic insufficiency, though aortic stenosis following IAA-B/VSD repair poses a surgically difficult problem.

Autologous pericardium for ventricular septal defect closure.

BACKGROUND AND AIMS OF THE STUDY: The use of living, untreated autologous pericardium for patch repair in the left ventricular outflow tract was considered attractive in children. METHODS: Ventricular septal defect (VSD) closure with an untreated autologous pericardial patch was performed in 102 children of mean age 13.4 months (range: 1 to 73 months). Postoperative transthoracic Doppler echocardiography was performed in all children at a mean of nine weeks (range: one day to 50 weeks) after surgery. One pericardial patch, which was explanted at autopsy two months after surgery, was studied microscopically. RESULTS: At short-term follow up, no or only minor residual VSD was found in 97 patients, moderate VSD in two and severe VSD in one patient. One patient was reoperated for residual VSD and an aneurysmic patch first diagnosed seven days after surgery. Two more patients showed ballooning of the patch without VSD after five and seven days respectively. All aneurysmic patches were attributed to intraoperative patch oversizing. Patch integrity was confirmed in all other patients. No inflammatory or degenerative changes were observed at microscopy, rather a remodeling response had caused the patch to thicken, indicating an adaptation of the living tissue. CONCLUSIONS: The untreated autologous pericardial patch has shown to be a safe alternative for VSD closure, provided that the patch is properly sized.

Pulmonary root replacement with the Freestyle stentless aortic xenograft in growing pigs.

BACKGROUND: The stentless xenograft with its favorable hemodynamic performance on the left side of the heart seems an attractive, readily available alternative for the reconstruction of the right ventricular outflow tract in children. METHODS: To assess its function in a preclinical animal investigation, we replaced the pulmonary root with a Freestyle stentless aortic xenograft in 18 piglets of 26.6 +/- 3.2 kg weight. The animals were allowed to grow as much as possible and slaughtered when symptoms of heart failure developed or body weight reached more than 160 kg. All valve explants were analyzed by gross examination and photography and, in 4 representative pigs, by histologic examination. RESULTS: Fourteen animals died prematurely after 2 weeks to 11 months. Twelve xenograft explants showed thick, immobilized, large nodular structures as cuspal remnants causing significant stenosis. At microscopy, large cuspal masses of degenerating collagen and fibrin and various inflammatory cells were frequently found. In the growing pig, most of the xenografts implanted in the pulmonary position showed early degeneration causing severe stenosis. CONCLUSIONS: Use of this valve for right ventricular outflow tract reconstruction in children cannot be recommended.

Disproportionate enlargement of the pulmonary autograft in the aortic position in the growing pig.

PURPOSE: This study was aimed to demonstrate growth in the pulmonary autograft after transplantation to the aortic position. METHODS AND MATERIALS: In 20 piglets (weight 25.4 +/- 3.5 kg) (mean +/- standard deviation) a Ross operation was performed and in five piglets (weight 9.3 +/- 0.7 kg) (mean +/- standard deviation) the ascending aorta was replaced with a valveless pulmonary autograft. Animals were allowed to grow as much as possible. Postmortem explanted autografts were studied by direct measurements of the valve cusps in the Ross group and of the wall segments in the valveless autograft group. Measurements of the first group were compared with the values of a separate control group, and values of the second group were compared with values of samples taken at operation. RESULTS: In the Ross group, cuspal weight, height, and width increased significantly by comparison with body weight (p < or = 0.003). The rate of increase did not differ significantly from that of the control group with a native pulmonary valve. However, there was a rapid adaptation of the autograft valves resulting in a significantly higher mean cuspal weight, height, and width. In the valveless autograft group, wall circumference, thickness, and height increased significantly (p < or = 0.001). The circumference increased significantly more than that of the native pulmonary wall. Compared with the native aortic wall, the pulmonary autograft media showed retained pulmonary architecture on microscopic study. CONCLUSION: These data suggest that the dimensional increase of the pulmonary autograft in the aortic position in the growing pig is determined by growth and dilatation, that the valve mass increases more than that of the native pulmonary valve, and that the characteristic pulmonary microscopic architecture is retained.