Partial Cavopulmonary Connection Research Articles

Catheter interventional closure of veno-venous collaterals in cyanotic patients after partial cavopulmonary shunts in pediatric patients: clinical practice review.

The development of veno-venous collaterals is an important and treatable cause of cyanosis in patients who had undergone partial cavo-pulmonary connection (PCPC) operations. Nevertheless, the literature on this complicated therapeutic option is sparse. Patients can present cyanosis either immediately after the operation (<30 days), which delays or hinders discharge from the intensive care unit or cyanosis may occur late: (>30 days and/or in another hospital admission), after the operation. Hence, transcatheter closure of veno-venous collaterals is the treatment of choice. Four patients were selected who showed cyanosis at variable durations after PCPC; the morphology of the collaterals and their hemodynamic effect was described and the strategy for closure of such abnormal vessels is suggested. Veno-venous collaterals described in our series were seen originating mainly or mostly from innominate vein angles. The drainage sites were either above the diaphragm into a cardiac structure: the coronary sinus (CS) and/or atria; or below the diaphragm into the inferior vena cava (IVC) or hepatic veins through the paravertebral venous system and/or the azygous system. It is stated in the literature that several types of devices and coils can be used to close the collaterals such as the Amplatzer vascular plugs (AVPs), Amplatzer duct occluder II (ADOII), non-detachable and detachable coils. In this clinical review, the technical details that determine device type and size are explained. The recent generations of hydrogel-coated coils were also used in this series of patients to close the difficult types of collaterals with better results. All described vessels were closed successfully, without any complications. The patients had a significant rise in their transcutaneous oxygen saturations and hence, a clear clinical benefit.

Outcomes After Bidirectional Glenn Shunt in a Tertiary-Care Pediatric Hospital in South Africa

Large data sets have been published on short- and long-term outcomes following bidirectional Glenn surgery (BDG), or partial cavopulmonary connection, in high-income countries. Data from low-income and middle-income countries are few and often limited to the immediate postoperative period. The primary outcome was any in-hospital postoperative complication, assessed according to predefined criteria, in children who underwent BDG surgery at Red Cross War Memorial Children's Hospital. A retrospective cohort study. A tertiary teaching hospital. The study authors identified 61 children (<18 years of age) who underwent BDG over 8 years. The median age of patients undergoing BDG was 2.5 years (interquartile range, 1.4-5.5 years). BDG surgery. Thirty-five patients (57.4%) had a postoperative complication, with some patients (17 of 61, 27.9%) having more than 1 complication. The most frequent complications were infective (29.5%). Univariate analysis found that postoperative complications were associated with the use of nitric oxide (p=0.004) and a longer duration of anesthesia (p=0.045) and surgery (p=0.004). Patients with complications spent longer in the pediatric intensive care unit (ICU) (p < 0.001) and in the hospital (p < 0.012). On multivariate analysis, a priori risk factors based on previous studies were not found to be statistically significant. A total of 37.3% of patients completed their single-ventricle palliation, and 30.5% of patients were lost to follow-up. Important findings were the older age at which the BDG was performed compared to high-income countries, an acceptable mortality rate of 3.3%, infection being the most common complication, the association of a complication with increased ICU and hospital lengths of stay, and the high rate of patients lost to follow-up.

Conexão cavopulmonar parcial como primeiro estágio no tratamento do coração univentricular em um centro na Amazônia: resultados imediatos

Objetivo: Analisar a eficácia da conexão cavopulmonar parcial como paliação primária no tratamento do coração univentricular em pacientes com mais de três meses. Métodos: Foram avaliados retrospectivamente os prontuários de pacientes portadores de cardiopatias congênitas com fisiologia univentricular submetidos à conexão cavopulmonar como primeiro estágio. Foram avaliados os seguintes parâmetros: idade, sexo, diagnóstico anatômico, cardiopatias associadas, tempo de circulação extracorpórea, tempo de intubação, tempo de internação hospitalar, complicações pós-operatórias, saturação periférica de oxigênio e da pressão sistólica da artéria pulmonar pré e pós-operatória. Resultados: Foram identificados 11 casos de crianças submetidas a conexão cavopulmonar parcial como paliação primária. A média de idade foi 10,54 meses, com leve prevalência do sexo feminino (54,54%). As principais características anatômicas das cardiopatias foram Atresia tricúspide e Ventrículo Único tipo esquerdo. Houve aumento na saturação de oxigênio variando de uma média de 74,46% para 88,27% (p&lt;0,01), com adequação da pressão sistólica de artéria pulmonar de 20,80mmHg para 17,80mmHg (p&lt;0,05). Ocorreram dois casos de paresia frênica e um caso de quilotórax os quais foram corrigidos cirurgicamente. Não houve óbitos na amostra. Conclusão: A conexão cavopulmonar parcial como paliação primária no tratamento do coração univentricular teve resultados imediatos satisfatórios quando realizada após os três meses de idade.

Surgery of single ventricles in humanitarian practice: surgery for which patients?

To analyse the feasibility and effectiveness in humanitarian practice of surgical management of children with single-ventricle heart condition. Retrospective study of children with a single ventricle, managed by the association Mécénat-Chirurgie Cardiaque since 1996, with long-term follow-up after their return home. Of the 138 children in our cohort, 119 had one or more surgeries (180 procedures): palliative surgery alone (systemic-pulmonary anastomosis or banding), 41; partial cavo-pulmonary connection, 47; total cavo-pulmonary connection (mean age 8.5 years), 31. Operative mortality is 5.5%. After a mean follow-up of 5.6 years, 18 children (13%) were lost to follow-up. Survival at 10 years is 79% in children receiving surgery (palliative only, 72%; partial cavo-pulmonary connection, 77%; total cavo-pulmonary connection, 97%) versus 29% in children with no surgical intervention. The prognosis is better for tricuspid atresia and double-inlet left ventricle (86 and 83% survival at 10 years) than for double-outlet right ventricle or complete atrio-ventricular canal defect (64 and 68% at 5 years). The surgery of the single ventricle in humanitarian medicine allows a very satisfactory survival after one or more surgeries tending towards a total cavo-pulmonary connection as soon as possible.

Ventricular morphology does not impact mid-term outcome after extracardiac total cavopulmonary connection

Right ventricular morphology is a known risk factor for death in patients with univentricular hearts (UVH), especially before partial cavopulmonary connection. This study investigates the influence of anatomic and procedure related factors on mid-term outcome after extracardiac total cavopulmonary connection (TCPC). Retrospective single-center analysis of all patients with UVH undergoing extracardiac TCPC from 2000 to 2005. Patient and procedure related variables were analyzed. 100 patients underwent extracardiac TCPC in the study period. 69% had a dominant left ventricle, 23% had a dominant right ventricle and 8% had biventricular anatomy. Median age at intervention was 6.1 years (1.1–29.4). At the moment of surgery, 9% were in NYHA class > 2 or had preoperative univentricular dysfunction. 6% had significant atrioventricular valve (AVV) regurgitation. Median preoperative mean pulmonary pressure was 12 mmHg (6–21). Early mortality was 4% and global mortality was 8%. Anatomic, functional, perioperative and postoperative parameters did not impact mortality. Only preoperative NYHA class > 2 was significantly associated to higher global mortality in univariate analysis. Freedom from death/transplantation was 92.6% (95% CI ± 0.05) at 5 years and 91.4% (95% CI ± 0.06) at 10 years after TCPC. Ventricular morphology did not influence global mortality (log rank P = 0.22) or mid-term morbidity (thrombosis, protein loosing enteropathy, arrhythmia; log rank P = 0.76). Median follow-up was 8.9 years (0.01–14). At last visit, 96% of patients were in NYHA 1-2 with mostly (71%) normal univentricular function. Mid-term outcome after extracardiac TCPC is excellent with a good functional result and appears not to be influenced by ventricular morphology. Further studies are needed to evaluate the possible impact of ventricular morphology on late outcome after TCPC.

Craniosynostosis surgery in an infant with a complex cyanotic cardiac defect

We report on a case where craniosynostosis surgery for a left-sided coronal synostosis was performed successfully on an 11-month old infant with a hypoplastic left ventricle with a dysplastic mitral valve, double outlet right ventricle, transposition of the great arteries, atrial septal defect, multiple ventricular septal defects, and surgically applied pulmonary banding. Craniosynostosis surgery is considered high-risk surgery, because of possible sudden and extensive blood loss, and is usually performed in cardiopulmonary healthy children. Children with congenital heart disease undergoing noncardiac surgery have an increased risk of perioperative morbidity and cardiac arrest. Patients with hypoplastic left heart syndrome are a high-risk population when undergoing noncardiac surgery, in all stages of palliation. This infant would be undergoing a partial cavo-pulmonary connection (PCPC) within a few months. With a PCPC, drainage of cranial vessels is dependent on passive flow via the superior caval vein directly into the pulmonary artery. Consequently, this could lead to an increased blood loss during craniosynostosis surgery. Therefore, it was decided to perform the craniosynostosis surgery first, before establishing a PCPC. When a child with CHD presents for high-risk noncardiac surgery, future cardiac procedures and physiology also have to be taken into account. A multidisciplinary approach, involving pediatric cardiologists and pediatric anesthesiologists, is essential in making this decision.

Only hepatic venous blood closes intrapulmonary shunts after cavopulmonary connection

In patients with a functional univentricular heart good results are nowadays accomplished with a staged approach to a total cavopulmonary connection (TCPC) [ [1] d'Udekem Y. Iyengar A.J. Cochrane A.D. et al. The Fontan procedure: contemporary techniques have improved long-term outcomes. Circulation. 2007; 116: I157-I164 PubMed Google Scholar ]. However, there are certain complications leading to a diminished quality of life as well as significant morbidity and mortality [ [2] Hess J. Long-term problems after cavopulmonary anastomosis: diagnosis and management. Thorac Cardiovasc Surg. 2001; 49: 98-100 Crossref PubMed Scopus (21) Google Scholar ]. Beside protein-losing enteropathy, plastic bronchitis, dysrhythmias, ventricular dysfunction and arteriovenous fistulas or venovenous collaterals due to increased venous pressure [ 2 Hess J. Long-term problems after cavopulmonary anastomosis: diagnosis and management. Thorac Cardiovasc Surg. 2001; 49: 98-100 Crossref PubMed Scopus (21) Google Scholar , 3 Lenz D. Hambsch J. Schneider P. et al. Protein-losing enteropathy in patients with Fontan circulation: is it triggered by infection?. Crit Care. 2003; 7: 185-190 Crossref PubMed Scopus (48) Google Scholar ], microscopic intrapulmonary shunts are one of the major complications [ [4] Bernstein H.S. Brook M.M. Silverman N.H. Bristow J. Development of pulmonary arteriovenous fistulae in children after cavopulmonary shunt. Circulation. 1995; 92: II309-II314 Crossref PubMed Google Scholar ]. The incidence is reported to be up to 25% [ [5] Cloutier A. Ash J.M. Smallhorn J.F. et al. Abnormal distribution of pulmonary blood flow after the Glenn shunt or Fontan procedure: risk of development of arteriovenous fistulae. Circulation. 1985; 72: 471-479 Crossref PubMed Scopus (162) Google Scholar ]. The pathophysiology of these shunts is discussed and associated with a so-called liver factor. It has been observed, that the shunts become present in lungs without direct perfusion with hepatic venous blood, which means hepatic venous drainage has to pass another capillary bed first [ [6] Srivastava D. Preminger T. Lock J.E. et al. Hepatic venous blood and the development of pulmonary arteriovenous malformations in congenital heart disease. Circulation. 1995; 92: 1217-1222 Crossref PubMed Scopus (304) Google Scholar ]. The absence of venous hepatic blood flow into the lungs then leads to development and progression of the intrapulmonary shunts. This is the case in patients with partial cavopulmonary connection (PCPC) or after completion to TCPC with the hepatic venous drainage being directed mainly to one lung. The liver-factor-hypothesis is also supported by the fact that the shunts disappear after redirecting hepatic venous blood to the affected lung [ 7 Shah M.J. Rychik J. Fogel M.A. Murphy J.D. Jacobs M.L. Pulmonary AV malformations after superior cavopulmonary connection: resolution after inclusion of hepatic veins in the pulmonary circulation. Ann Thorac Surg. 1997; 63: 960-963 Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar , 8 Praus A. Eicken A. Balling G. Schreiber C. Hess J. Progressive intrapulmonary shunting in a child after bidirectional Glenn operation only resolved after total cavopulmonary completion. Int J Cardiol. 2008; 128: e12-e15 Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar ]. However, the exact pathophysiology or details about the hepatic factor are still not completely understood. In this study we analyzed the results of different therapeutic approaches in patients with severe intrapulmonary shunting and functional univentricular heart.

272: Long-term outcome of 117 patients with univentricular heart and common atrioventricular valve

Few studies investigated the long-term outcome of patients with univentricular heart and common atrioventricular valve. We retrospectively analysed the medical files of all patients univentricular heart with common atrioventricular valve in the setting of heterotaxy or with unbalanced atrioventricular septal defect preventing biventricular repair. 117 patients were identified during the study period. 89/117 had a postnatal diagnosis. 28/117 patients never underwent surgery, 25/117 underwent one palliation surgery (Blalock-Taussig-shunt (BTS)/ pulmonary banding), and finally, 61/117 patients entered a sequential cavopulmonary connection program: 37/61 had partial cavopulmonary connection at the time of data analysis while 24/61 had total cavopulmonary connection (TCPC). The average age at TCPC was 7.6 years +/-4 years [1.7-16 years]. Three patients were eventually transplanted. The overall mortality was 59% (69/117): 65% and 30% in heterotaxy and in patients with unbalanced atrioventricular septal defect respectively. Mortality was 85% (24/28) in the subgroup of patients who never underwent surgery, 93% in the subgroup of patients who had a BTS, and 89% after pulmonary banding. In the subgroup planed to have TCPC, 49% died after partial cavopulmonary connection and survival rate was 71.6% [50.7-100] in patients who had TCPC. The long-term outcome of univentricular hearts with common atrioventricular valve treated in a tertiary referral center showed a high mortality rate. Patients with this kind of complex congenital heart disease should undergo the sequential univentricular program without delay in order to obtain better long-term survival.

A new surgical technique for transcatheter Fontan completion☆☆☆

Patients with complex congenital heart defects and univentricular heart usually required multiple palliative surgery aiming to separate pulmonary and systemic circulations. Various groups work on trying to perform the Fontan completion by a transcatheter technique. We developed and report here a modified technique to prepare the patient for this type of procedure. Sixteen sheep were included and prepared through a midline sternotomy. Preparation for transcatheter completion was performed using specially designed devices. The superior vena cava (SVC) was connected to the pulmonary artery (PA) using a Goretex conduit. The connection between the SVC and the right atrium (RA) was interrupted using a vascular stent occluded in the middle by a polytetrafluoroethylene (PTFE) membrane. Two nitinol rings were placed around the inferior vena cava (IVC). Immediately after preparation, the transcatheter completion was performed by first perforating the membrane of the occluded stent and by placing covered stents from IVC rings to the SVC stent. Creation of the SVC to PA connection was uneventful. The insertion of the rings was done successfully in all animals very easily. All stents but one were completely occluding the SVC. Once, a tiny leak was noticed and successfully treated by additional stitches around the stent. Perforation of the membrane was done successfully in all animals re-establishing the pathway between the SVC and the RA. After dilatation of the stent, one animal required surgical control of a haemorrhage related to disruption of the SVC anastomosis. Three to four Cheatham-platinum (CP)-covered stents were necessary to complete the Fontan-like circulation. In the first animal, one stent moved downward missing its target. The placement between the two rings was easily performed using fluoroscopic guidance. No stents were positioned above the SVC stent keeping this part free of material. We describe new improvements for surgical preparation for transcatheter completion of partial cavopulmonary connection. For superior connection, we developed an occluding stent that helps to re-establish RA to PA connection, alloys precise placement and enhances the stability of the completion stents. Inferiorly, anchorage of the covered stents is also improved by the use of nitinol rings.

Preoperative evaluation of candidates for total cavopulmonary connection: The role of echocardiography and cardiac catheterization

To evaluate the information provided by echocardiography and cardiac catheterization in patients with partial cavopulmonary connection (PCPC) with or without additional pulmonary blood flow (PBF) in whom total cavopulmonary connection (TCPC) was planned. We retrospectively evaluated the results provided by echocardiography and cardiac catheterization in 110 consecutive patients with PCPC (35 with isolated PCPC, 38 with associated antegrade PBF, 37 with associated retrograde PBF) in whom TCPC was planned. Eight patients had superior vena cava syndrome; all others suffered from cyanosis and fatigue. Pulmonary artery size could be determined in 54% of patients without additional PBF, in 47% of those with associated retrograde PBF and in 68% of those with associated PBF (p=0.20). Concomitant clinical signs of increased central venous pressure and echocardiographic signs of ventricular dysfunction and/or hypoplastic pulmonary arteries identified four patients in whom TCPC was not low-risk. PAP exceeding 16 mmHg was found in 9% of patients without and 16% of those with associated PBF (p=0.38). The Nakata index was higher in patients with associated antegrade PBF than in those without associated PBF (p=0.004) or in those with associated retrograde PBF (p=0.002). Of the 16 patients who needed concomitant interventional catheterization, 10 had associated retrograde PBF (p<0.05). In 11 patients (nine with and two without additional PBF), TCPC was contraindicated. Cardiac catheterization is still necessary before TCPC, mostly in patients with additional PBF, to identify those at risk and those needing interventional catheterization.

Nonfenestrated Extracardiac Total Cavopulmonary Connection in 132 Consecutive Patients

The study was conducted to assess the need for fenestration for completion of a total cavopulmonary connection (TCPC) with the most recent modification of an extracardiac conduit. The extracardiac approach was introduced to our institution in January 1999. Between June 2000 and June 2006, 132 consecutive patients were treated without a fenestration. At the time of TCPC, the median age was 31 months (range, 16 251), with 93 patients (70%) being younger than 48 months. Median patient weight was 12.5 kg (range, 9 to 66 kg). A previous partial cavopulmonary connection (PCPC) was accomplished in 117 patients (88.6%), without additional pulmonary blood flow. Thirty-day-mortality was 1.5%. Median time to extubation was 14 hours (range, 3 hours to 126 days). Initial pulmonary artery pressure value was 16.5 +/- 2.2 mm Hg, and 13.1 +/- 1.8 after extubation. Median drainage requirement was 4 days (range, 1 to 45), and median duration of hospitalization was 20 days (range, 5 to 128). Thirty-one (24%) required repeat drainage insertion. No subsequent fenestration was performed, and at hospital discharge no significant repeat effusions were observed. Multiple covariate logistic regression revealed longer time interval from PCPC to extracardiac TCPC (p = 0.006) as a significant predictor of pleural drainage lasting longer than 4 days, and older age at the time of extracardiac TCPC (p = 0.040) as a risk factor for hospitalization more than 20 days. Higher pulmonary artery pressure 3 hours postoperatively was a significant predictor for both outcome variables in the multivariate model (p = 0.013, p = 0.001). In general, an extracardiac TCPC can be performed without fenestration. Early staging of patients with functional single ventricle physiology may be one of the keys for these findings.

What was the impact of the introduction of extracardiac completion for a single center performing total cavopulmonary connections?

Creation of an extracardiac cavopulmonary connection has been proposed as a superior alternative to the lateral intracardiac tunnel for the completion of total cavopulmonary connection. We made a retrospective review of our experience with 125 patients undergoing a total cavopulmonary connection between June 1994 and January 2003. Our experience with the extracardiac connection for completion began in 1999. Since 1994, we have constructed an intracardiac tunnel in 50 patients, and an extracardiac connection in 75. Of the total number, 83 had undergone an earlier partial cavopulmonary connection. Additional intracardiac procedures were performed in 43 patients at time of completion, in 25 of those undergoing extracardiac completion, and in 18 of the patients having an intracardiac procedure. The mean size of the tube used for completion was 19 mm. The mean cross-clamp time for placement of the intracardiac tunnel was 77 min, with a median of 80.5 min, and a mean cardiopulmonary bypass time of 139 min, with a median of 131 min. For construction of the extracardiac connection, a mean cross-clamp time in 24 of the 75 patients was 54 min, with a median of 54 min. Mean cardiopulmonary bypass time for all the patients with an extracardiac connection was 100 min, with a median of 88 min. Reoperations were needed in 10 patients, 6 having intracardiac and 4 extracardiac procedures. Of these, 5 were early and 5 late, including one take down. None of the patients died after these interventions. Taken overall, 8 patients died, with 5 early deaths. In the multivariable analysis, cardiopulmonary bypass time of more than 120 min, atrioventricular valvar replacement, and banding of the pulmonary trunk prior to the total cavopulmonary connection, all reached statistical significance for early death, whereas only heterotaxy syndrome remained as the sole risk factor for late death. There was no significant difference in survival between the modifications used. Whereas we could not identify any clinical superiority for the extracardiac approach in the short-term, the concept of extracardiac completion has helped to simplify the overall procedure. Longer follow-up will be required to elucidate any potential advantages.

Perforation of the atretic pulmonary valve: long-term follow-up

ObjectivesWe evaluated the long-term results of perforation of the pulmonary valve in patients with pulmonary atresia with an intact ventricular septum (PA-IVS). BackgroundInterventional perforation of the pulmonary valve is considered the elective first stage treatment for PA-IVS, particularly in patients with a tripartite right ventricle (RV) and normal coronary circulation. However, the long-term results of this procedure are lacking. MethodsBetween January 1991 and December 2001, 39 newborns with a favorable form of PA-IVS underwent attempted perforation of the pulmonary valve. We evaluated the early and long-term outcomes. ResultsMedian tricuspid and pulmonary zvalues were −1.2 and −2.4, respectively. Perforation was successful in 33 patients. Among them, 17 needed neonatal surgery, 13 did not need any surgery, and 3 had elective surgery after the first month of life. There were two procedure-related deaths, seven nonfatal procedural complications, and four postsurgical deaths. Compared with patients needing neonatal surgery, those having no or elective surgery had a higher incidence of a tripartite RV and a higher median tricuspid zvalue (92% vs. 53%, p = 0.04 and −1.7 vs. −0.5, p = 0.03). At a median follow-up of 5.5 years (range 0.5 to 11.5), survival was 85% and freedom from surgery was 35%. Five patients, four of whom had neonatal surgery, underwent a partial cavo-pulmonary connection. ConclusionsOur results show that this technique, although burdened by non-negligible mortality and morbidity, is effective in selected patients with a normal-sized RV. Preselection of patients allows interventional or surgical biventricular correction in the majority of cases.

More Accurate Quantification of Pulmonary Blood Flow by Magnetic Resonance Imaging Than by Lung Perfusion Scintigraphy in Patients With Fontan Circulation

Quantitative evaluation of pulmonary perfusion using lung perfusion scintigraphy in patients with atriopulmonary anastomosis (APA) or total cavopulmonary connection (TCPC) or partial cavopulmonary connection (PCPC) is difficult because of preferential draining of the venae cavae to one lung. Scintigraphy is the gold standard. Phase-velocity MRI (PV-MRI) is a new technique for determining pulmonary perfusion. The aim of this study was therefore to determine whether PV-MRI is more accurate than scintigraphy for quantitative evaluation of pulmonary perfusion ratios in patients with APA, TCPC, or PCPC. We studied 15 patients with APA, TCPC, or PCPC (16+/-7 years old, 4 female). Twelve patients (15+/-8 years old, 3 female) with a single pulmonary blood source supplied by a subpulmonary ventricle, ensuring complete mixing of the radioactive tracer before entering the pulmonary circulation, served as controls. Pulmonary scintigraphy and PV-MRI were performed in all patients. Bland-Altman analysis showed a clinically unacceptable difference of 7.1% right pulmonary blood flow (27.2% upper and -13.0% lower limit of agreement) between the two methods in the study group. The two methods agreed excellently in the control group (difference, 1.6%; 4.0% upper and -7.2% lower limit of agreement), showing that the bad agreement in the study group was caused by the problems encountered using pulmonary scintigraphy in patients with APA, TCPC, or PCPC. Because of preferential caval flow into either lung, PV-MRI is more accurate for evaluating pulmonary perfusion ratios than lung perfusion scintigraphy in patients with Fontan-like circulation.

Histomorphometric analysis of pulmonary vessels in single ventricle for better selection of patients for the Fontan operation

Objective: In cases of single-ventricle physiology, the Fontan procedure often fails even when the usual selection criteria are strictly respected. We analyzed specimens from intraoperative open lung biopsies performed on 40 patients with single-ventricle physiology who were considered to be good candidates for the Fontan procedure. Histomorphometric study was performed to determine histologic factors predictive of failure of the Fontan procedure. Methods: Histomorphometric studies were performed on samples from 40 patients aged 6 months to 23 years with single-ventricle physiology, either tricuspid atresia (n = 14) or univentricular heart (n = 26). The preoperative pulmonary arterial pressure was 18 mm Hg or less in 35 cases and greater than 18 mm Hg in 5 cases. Eighteen patients underwent total cavopulmonary connection, 16 patients underwent partial cavopulmonary connection, and 6 underwent a palliative procedure, as determined according to clinical and hemodynamic findings. Results: Lung biopsy specimens from all 5 patients with pulmonary arterial pressure greater than 18 mm Hg appeared abnormal, whereas they appeared abnormal only 51% of the time in the low pulmonary arterial pressure group. The most frequent histologic abnormality observed was extension of smooth muscle cells in the wall of distal intra-acinar pulmonary arteries. Of the 18 patients who underwent the Fontan procedure, 9 had normal distal pulmonary arteries and good surgical results (except 1 with the Fontan circulation taken down for an anatomic reason). The remaining 9 had thick-walled distal intra-acinar pulmonary arteries with poor results of the Fontan procedure, and 6 died. The mean percentage wall thickness of small intra-acinar pulmonary arteries was significantly greater among the patients with bad results than among those with good results of the procedure (P < .01). Conclusions: Lung biopsy specimens were abnormal in 51% of patients with low pulmonary arterial pressure, there was no relationship between preoperative pulmonary arterial pressure and outcome, and extension of muscle in peripheral arteries was always present in cases of failure of the Fontan procedure. Histomorphometric study is therefore a useful adjunct to the usual selection criteria for surgical decision making in cases of single-ventricle physiology.

CONNECTION GEOMETRY AFFECTS RESISTANCE TO FLOW IN FONTAN CONNECTIONS: IN VITRO STUDIES † 174

Recent modifications to the original Fontan procedure have placed emphasis on the nature of the connection between the cavae and the pulmonary arteries. Since there is no ventricle acting as a pump to drive blood through the pulmonary circulation, a critical determinant of outcome is the overall resistance to flow across the surgical connection and pulmonary circuit. This study addressed the hypothesis that Fontan connection geometry significantly affects resistance to flow. Methods: Connections of the following three types were performed on explanted canine hearts; (1) atriopulmonary connection (APC), (2) lateral tunnel total cavopulmonary connection (TCPC) and(3) partial cavopulmonary connection (intra-atrial baffle with posterior cavo-atriopulmonary connection) (PCPC). Anatomically correct transparent urethane flow models were constructed using injection molding and casting procedures. The models were perfused using a blood analog fluid at flow rates ranging from 2-7 L/min. A variable voltage pumping system allowed input voltage, which can be related to the rate of energy expenditure, to be recorded for each flow condition. Results: Resistances at constant flow differed for each geometry (p<.01). The TCPC had the lowest values of resistance for equivalent flows through each model followed by the PCPC and the APC. Resistance differentials increased with flow rate for each model(p<.05). Conclusions: Based on these experiments, we conclude that a lateral tunnel TCPC offers the least resistance flow among these commonly used connections. The observed increase in resistance differentials with flow may have implications regarding exercise capacity and suggests that minimizing resistance in the Fontan circuit may have significant implications for postoperative morbidity and survival. Figure