Source Of Pulmonary Blood Flow Research Articles

Shunt Type in the Norwood Procedure

Source: Ohye RG, Sleeper LA, Mahony L, et al. Comparison of shunt types in the Norwood procedure for single-ventricle lesions. N Engl J Med. 2010; 362(21): 1980– 1992; doi: 10.1056/NEJMoa0912461The Pediatric Hear t Network conducted a clinical trial at 15 North American centers of infants with hypoplastic left heart syndrome (HLHS) or related single right ventricle anomalies who were scheduled for a stage I repair (Norwood procedure) and were randomized to have either a Sano (right ventricle to pulmonary artery [RVPA]) shunt or a modified Blalock Taussig (MBT, subclavian artery to PA) shunt to provide pulmonary blood flow. The primary outcome was death or cardiac transplantation within 12 months following the intervention. Secondary outcomes included morbidity during the hospitalizations for the Norwood and the stage II (Bidirectional Glenn) procedures; unintended cardiovascular interventions involving the shunt; function and volume of the right ventricle; and the amount of tricuspid-valve regurgitation at discharge following the Norwood procedure, before stage II, and at 14 months of age.The study enrolled 555 infants but six were excluded from the analysis (5 did not receive the intervention and 1 was lost to follow-up). The two equally divided groups did not differ in initial clinical characteristics. Twelve months after randomization, primary outcome events occurred in 72 (68 deaths and 4 transplantations) of the 274 infants (26.3%) assigned to the RVPA group as compared to 100 events (91 deaths and 9 transplantations) of the 275 infants (36.4%) assigned to the MBT group. However, there was no difference in transplantation-free survival between the two groups with continued follow-up to a mean of 32 months after the stage I procedure.During the 12 months following the Norwood procedure, infants in the RVPA shunt group underwent more unplanned cardiovascular interventions (92 vs 70 per 100 infants, P=.003) primarily due to the higher need for balloon dilation or stent placement in the shunt or a branch of the PA. The rate of complications was also higher in the RVPA shunt group (5.3 vs 4.7 complications per infant, P=.002), although the proportion of infants with at least one complication was the same (91%). The authors concluded that continued follow-up beyond 12 months is needed to determine which of the two shunts to establish pulmonary blood flow is superior.HLHS occurs in 1 of 5,000 live births.1 Infants with HLHS require surgical therapy to establish adequate systemic blood flow that is separate from the pulmonary circulation. The risk of death is high, especially during the initial Norwood surgery and the interstage period until a bidirectional cavopulmonary anastomosis (Stage II procedure) is performed. This time period encompasses the duration the child has single ventricle physiology — approximately the first six months of life.Much interest was generated when Sano and colleagues first described their success modifying the source of pulmonary blood flow from an arterial (MBT) to a ventricular (RVPA) shunt for the first stage palliation pioneered by Norwood and colleagues.2,3 Results from several institutions demonstrated that an RVPA shunt improved survival through the period of single ventricle physiology compared to a MBT shunt, perhaps due to better coronary perfusion associated with higher diastolic blood pressure. However, concern persisted that the physiologic advantages of a RVPA shunt for early survival may be offset by the adverse effects of the required ventriculotomy on long-term cardiac function and arrhythmogenesis.To address these concerns, in the current study the Pediatric Heart Network completed a randomized trial of shunt type for initial surgical palliation. The results validate the survival advantage of the ventricular shunt for the first year after the initial surgery, but found no difference in transplant-free survival between groups after one year.Echocardiography is the primary method for assessment of ventricular function over time. Previous data comparing ventricular function between shunt types is limited, and in the current trial echocardiography findings at 14 months post initial palliation did not differ between the two shunt types. Nonetheless, other reports of concerning findings, including pathological specimens showing fibrosis and collagen changes4 and catheterization findings suggesting decreased cardiac contractility5 in RVPA shunts are concerning. Additional follow-up of the population in this study should further elucidate whether a RVPA shunt negatively impacts ventricular function in the long term compared to the MBT. Thus far there have been few reports of arrhythmias in HLHS patients with either shunt type.6Congenital heart research teams plan a more detailed analysis of data from this trial and continued follow-up of this population. The important message for primary care physicians who take care of patients with HLHS and their families is that the morbidity and mortality do not vanish after the stage II procedure regardless of shunt type. Close follow-up is required to allow timely interventions.

Heart Transplantation Techniques after Hybrid Single-Ventricle Palliation

The Norwood procedure for hypoplastic left heart syndrome (HLHS) aims to provide an unobstructed systemic outflow tract, unrestrictive inter-atrial communication, controlled source of pulmonary blood flow, and reliable source of coronary blood flow. The hybrid palliative strategy of pulmonary artery banding and ductal stenting has emerged as an alternative treatment for neonates with HLHS. Neonates who have undergone a hybrid Norwood but are not candidates for the three-stage single-ventricle pathway may need heart transplantation. Patients who have undergone hybrid Norwood or those with visceral heterotaxy who have undergone ductal stenting and bilateral PA bands represent a technically challenging group of patients for heart transplantation, but it appears to be a favorable approach and we describe our experience with three patients who underwent heart transplant after a hybrid Norwood procedure.

Outcome of the Modified Norwood Procedure: 7 Years of Experience from a Single Institution

Background: We assessed the early and mid-term results of the modified Norwood procedure for first-stage palliation of hypoplastic left heart syndrome (HLHS) and its variants to identify the risk factors for hospital mortality. Material and Method: Between March, 2003, and December, 2009, 23 patients (18 males and 5 females) with HLHS or variants underwent the modified Norwood procedure. The age at operation ranged from 3 to 60 days (mean, 11.7±13.2 days) and weight at operation ranged from 2.2 to 4.8 ㎏ (mean, 3.17±0.52 ㎏). We used a modified technique that spared the anterior wall of the main pulmonary artery in 20 patients. The sources of pulmonary blood flow were RV-PA conduit in 15 patients (group Ⅰ) and RMBTS in 8 (group Ⅱ). Follow-up was completed in 19 patients (19/20, 95%) in our hospital (mean 26.0±22.8 months). Result: Early death occurred in 3 patients (3/23, 13%), of whom 2 had TAPVC. Fourteen patients underwent subsequent bidirectional cavopulmonary connection (BCPC, stage 2) and seven underwent the Fontan operation (stage 3). Three patients died between stages, 2 before stage 2 and one before stage 3. The estimated 1-year and 5-year survival rates were 78% and 69%, respectively. On multivariate regression analysis, aberrant right subclavian artery (RSCA) and associated total anomalous pulmonary venous connection (TAPVC) were risk factors for hospital mortality after stage 1 Norwood procedure. Conclusion: HLHS and its variants can be palliated by the modified Norwood procedure with low operative mortality. Total anomalous pulmonary venous connection adversely affects the survival after a stage 1 Norwood procedure, and interstage mortality rates need to be improved.

Occlusion of Sano conduit with the Amplatzer Vascular Plug: A reliable method for staged elimination of accessory pulmonary blood flow in single ventricle palliation

Staged palliative surgery is often required to regulate pulmonary and systemic blood flow in children with complex congenital heart disease. Accessory sources of pulmonary blood flow have been utilized to provide satisfactory pulmonary blood flow after Glenn anastomosis in select patients. Prolonged exposure to increased flow can lead to elevated pulmonary arterial pressures and volume loading of the ventricle, potentially limiting candidacy for Fontan completion. To review the feasibility, technique, and outcome of transcatheter closure of the Sano conduit utilizing the Amplatzer Vascular Plug (AVP). All patients who underwent device closure of the Sano conduit with an AVP were reviewed retrospectively. Patient demographics, indications, procedural details, and patient outcomes were reviewed. Hemodynamic changes before and after occlusion of the Sano conduit were compared. A P value < 0.05 was considered significant. Between 2005 and 2009, 11 male patients underwent Sano occlusion with an AVP. Average weight was 8.8 ± 2.2 kg. The Sano was occluded from both antegrade (n = 6) and retrograde (n = 5) approaches. Arterial saturation and mean pulmonary artery pressure both decreased significantly after Sano occlusion [86.9 ± 4.9% to 82.6 ± 4.9% (P < 0.001) and 14.1 ± 5 mm Hg to 12.8 ± 4 mm Hg (P < 0.05), respectively]. Conduit diameter averaged 3.6 mm (range 3.1-4.4) 13 months after Stage I palliation. The conduit was closed using a 6 mm AVP in nine patients and a 4 mm AVP in the other two. The ratio of AVP size to conduit diameter was 1.5 ± 0.27. There were no procedural complications and all patients at least 2 years of age have undergone Fontan completion. The Sano conduit can be left open in select patients who do not tolerate closure after Glenn anastomosis. It can be closed safely and effectively using the AVP. © 2010 Wiley-Liss, Inc.

In hypoplastic left heart patients is Sano shunt compared with modified Blalock–Taussig shunt associated with deleterious effects on ventricular performance?

A best evidence topic in congenital cardiac surgery was written according to a structured protocol. The question addressed was: in hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig (mBT) shunt associated with deleterious effects on ventricular performance? Sano shunt modification of Norwood procedure involves construction of a right ventricle to pulmonary artery (RV-PA) conduit as an alternative source of pulmonary blood flow. Compared with the mBT shunt, the RV-PA conduit provides a more stable haemodynamic state in the immediate postoperative period and is reported to be associated with lower interstage mortality. However, concerns regarding the impact of ventriculotomy on short- and long-term performance of single ventricle have been expressed. Altogether 101 papers were found using the reported search terms, from which seven represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. None of the echocardiographic or clinical outcome studies showed poor ventricular performance after ventriculotomy of the systemic RV for construction of Sano shunt. A small autopsy study of 11 patients showed greater remodelling of the ventricular myocardial extracellular matrix in patients with RV-PA conduit with potential implications for poor ventricular performance. We conclude that the current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in the short- and medium-term. However, all the existing studies are limited by small numbers, non-randomised design and retrospective nature with failure of correlation of echocardiographic indices to clinical outcomes. It is expected that the Pediatric Heart Network randomised controlled trial will address this important issue.

Amplatzer occlusion of accessory ventriculopulmonary connections

Children with complex congenital heart disease often require staged palliation to regulate systemic and pulmonary blood flow. Accessory sources of pulmonary blood flow including aortopulmonary collaterals, aortopulmonary shunts, and ventriculopulmonary connections following Glenn or Fontan palliation can be associated with elevated central venous pressures and persistent pleural drainage. Occlusion of accessory ventriculopulmonary connections in this setting has traditionally been accomplished surgically. To review the efficacy of Amplatzer devices in transcatheter occlusion of accessory ventriculopulmonary connections in children with complex congenital heart disease. Patients were identified and their records retrospectively reviewed for indication, procedural details, and clinical efficacy and outcome. Between December 2004 and March 2008, seven patients underwent occlusion of accessory ventriculopulmonary connections using an Amplatzer Septal Occluder (3), an Amplatzer Duct Occluder (3), or an Amplatzer Vascular Plug (1). Underlying single ventricle physiology was present in six of these patients. The site of occlusion was the right ventricle to pulmonary artery (Sano) conduit in two patients, the native main pulmonary artery in three patients, the pulmonary valve in one patient, and a left ventricle to pulmonary artery homograft in one patient with biventricular physiology. There were no complications associated with these procedures. Amplatzer occlusion devices provide a safe and effective means of eliminating accessory ventriculopulmonary connections in children who have undergone surgical palliation of congenital heart disease.

1067 MR assessment of long term pulmonary arterial morphology following surgical ligation of systemic to pulmonary arterial shunts: visualising a potential risk

Introduction Formation of a Blalock-Taussig (BT) shunt to establish a secure source of pulmonary blood flow is the first stage of palliation for a significant proportion of children born with congenital heart disease. With further palliative or corrective surgery, ligation rather than surgical division of a previously-formed BT shunt has been the preferred surgical strategy. We hypothesise that ligation rather than division of a shunt carries a risk of iatrogenic vascular constraint with respect to the pulmonary arteries, producing distortion with somatic growth.

Successful cardiac transplant after Berlin Heart bridge in a single ventricle heart: Use of aortopulmonary shunt as a supplementary source of pulmonary blood flow

Pulsatile ventricular assist devices, and in particular the Berlin Heart Excor infant ventricular assist device (Berlin Heart; Berlin Heart AG, Berlin, Germany), have rarely been used to support infants and small children with single ventricle.1,2 We report successful cardiac transplantation in an infant with single ventricle supported with a Berlin Heart.

Surgical outcome for patients with the mitral stenosis–aortic atresia variant of hypoplastic left heart syndrome

We sought to identify and characterize a subgroup of patients with hypoplastic left heart syndrome who might be at higher risk for stage I failure. From January 2001 through December 2006, all patients with hypoplastic left heart syndrome who underwent stage I palliation at Children's Hospital Boston were retrospectively reviewed. The subgroup with the mitral stenosis-aortic atresia variant was studied separately. We evaluated preoperative echocardiographic data, operative characteristics, and postoperative factors associated with death or the need for transplantation. The Kaplan-Meier method was used to assess survival. Thirty-eight (23%) of 165 patients had mitral stenosis-aortic atresia. Hospital mortality or need for transplantation for patients with mitral stenosis-aortic atresia was significantly higher than for other anatomic subgroups (29% vs 7.9%, P = .002). Left ventricle-subepicardial coronary artery communications were present in 20 (53%) patients with mitral stenosis-aortic atresia and were associated with a significantly higher hospital mortality (50% vs 6%, P = .004). No difference in outcome was demonstrated between different sources of pulmonary blood flow. A longer cardiopulmonary bypass time (P = .02) and the need for postoperative extracorporeal membrane oxygenation support (P < .001) were associated with a higher mortality rate. With improved outcomes in the management of neonates with hypoplastic left heart syndrome, those with the mitral stenosis-aortic atresia variant and left ventricle-subepicardial coronary artery fistulae have emerged as a higher-risk subgroup for failure of stage I palliation. Further investigation is required, and a change in clinical management strategy for this particular subgroup might be warranted.

Effect of Shunt Type on Echocardiographic Indices After Initial Palliations for Hypoplastic Left Heart Syndrome: Blalock-Taussig Shunt Versus Right Ventricle-Pulmonary Artery Conduit

The study objective was to compare echocardiographic indices in infants with hypoplastic left heart syndrome (HLHS) randomized to different surgical pathways. Initial surgical palliation for HLHS has evolved to two strategies that vary by source of pulmonary blood flow: a modified Blalock-Taussig (BT) shunt or a right ventricle to pulmonary artery (RV-PA) conduit. Seventeen patients were randomized to either a BT shunt or RV-PA as their first-stage palliation, and 15 survived through bidirectional Glenn (BDG) (seven BT shunts/eight RV-PAs). Echocardiography was performed pre-stage 1 palliation (S1P), early post-S1P, pre-BDG, and post-BDG. Echocardiographic measurements included indices of right ventricle function and shape, right ventricle myocardial performance index, neoaortic Doppler flow patterns and cardiac output, Doppler inflow and tissue imaging, and conduit/neoaortic regurgitant fraction. There were no significant differences in right ventricle size, shape, or estimates of systolic and diastolic function between groups. Patterns of changes in neoaortic Doppler flow in the RV-PA conduit group showed a decrease in all indices of systemic flow early after initial palliation, but these measures consistently increase later post-S1P and post-BDG. In contrast, the BT shunt group increases these same indices post-S1P and pre-BDG with a decrease after shunt removal. Right ventricle size and function do not appear significantly affected by surgical type of initial palliation for HLHS, and this correlates with early outcome. Echocardiographic Doppler findings correlate well with the expected physiologies of the different shunts as these infants progress through initial palliative strategies.

Síndrome do coração esquerdo hipoplásico: estratégia cirúrgica e comparação de resultados com técnicas de Norwood x Sano

To report a surgical strategy for the Norwood procedure in the hypoplastic left heart syndrome (HLHS) that enables short hypothermic circulatory arrest time and aortic arch reconstruction with autologous pericardium patch. To compare the results of the modified Blalock-Taussig (mBT) shunt and the right ventricle-to-pulmonary artery (RV-PA) conduit procedures as the source of pulmonary blood flow. Retrospective study of 78 newborns consecutively operated between March, 1999 and June 2006. One technique for reconstruction of the neoaorta and two different techniques for reestablishment of the pulmonary blood flow: the mBT shunt in the first 37 newborns and RV-PA conduit in the last 41. Cannulation of the ductus arteriosus for systemic perfusion was the main part of the surgical strategy to reduce the hypothermic circulatory arrest time. In-hospital survival for the entire cohort was 74,35%, or 67.57% for the mBT shunt and 80,49% for RV-PA conduit groups (p=0,21). Hypothermic circulatory arrest times were 45.79+/-1.99 min and 36,8+/-1,52 min (p=0,0012), respectively. Mortality rates between first and second stages were 40% for the mBT shunt and 6,9% for RV-PA conduit groups (p=0,007). Late coarctation of the aorta occurred in five patients Actuarial survival curves(Kaplan-Meier) comparison showed better results with VD-AP conduit (p=0,003). This surgical strategy resulted in short circulatory arrest time, low mortality and low incidence of aortic coarctation. Although the higher rate of survival to first palliation stage with the RV-PA conduit was not significant, the lower interstage mortality and superior medium-term survival in RV-AP group were statistically advantageous.

The Modified Blalock–Taussig Shunt Versus the Right Ventricle-to-Pulmonary Artery Conduit for the Norwood Procedure

The initial Norwood procedure remains the highest risk operation for the staged repair of univentricular congenital malformations with associated systemic outflow obstruction. The modified Blalock-Taussig shunt (MBTS) has been implicated as a major cause of not only the operative mortality, but also associated morbidity and interstage attrition. The etiology of these events has often been attributed to the diastolic runoff and "coronary steal" associated with the MBTS, in addition to the delicate balance between systemic and pulmonary blood flow that characterizes all systemic-to-pulmonary artery shunts. Recently, there has been renewed interest in the right ventricle-to-pulmonary artery conduit as a source of pulmonary blood flow for the Norwood procedure as a potential method for minimizing the negative aspects of the MBTS. The current literature is contradictory, retrospective, and predominantly historically controlled. The Trial of Right Ventricular vs Modified Blalock-Taussig Shunt in Infants with Single Ventricle Defect Undergoing Staged Reconstruction, a randomized controlled clinical trial comparing the two techniques, is ongoing and may provide answers to this controversy.

Pulmonary Atresia With Intact Ventricular Septum: Initial Management

Outcomes for pulmonary atresia with intact ventricular septum are suboptimal, while initial management remains controversial. This study was undertaken to determine the effect of catheter-based therapy on the need for early surgical intervention. A single-institution retrospective chart review was made of all 25 neonates with pulmonary atresia with intact ventricular septum from 1999 to 2005. Mean age at first intervention was 3.1 +/- 2.2 days, mean weight 3.3 +/- 0.5 kg. Right ventricular hypoplasia varied: 20% normal, 16% mild, 28% moderate, 28% moderately severe or severe, 8% not classified. Median tricuspid valve z-score was -2.3 +/- 2.6. First intervention was catheter-based therapy in 56% (14 of 25), operative in 36% (9 of 25), and no therapy in 2. Technically adequate valvotomy was achieved in 79% (11 of 14). Serious catheter-related complications occurred in 3 of 14 (21%). Only 5 of 14 (36%) with catheter-based therapy weaned from prostaglandins without surgery. Of these, 2 required surgery for cyanosis at 1 and 3 months. Surgery after catheter-based therapy consisted of right ventricular outflow patch in 36% (4 of 11), systemic to pulmonary shunt in 64% (7 of 11). Median time between catheter-based therapy and surgery was 8.5 days (range, 1 to 89). Only 3 of the 23 treated patients avoided operation during infancy. There was 1 early and 1 late death after operation after initial catheter-based therapy, and 1 late death after primary surgery alone during a mean follow-up of 33 months (range, 1.5 to 79). Balloon valvotomy alone for pulmonary atresia with intact ventricular septum rarely obviates the need for an additional source of pulmonary blood flow--either shunt or ductal stenting.

Advances in Neonatal Cardiac Surgery

After completing this article, readers should be able to: 1. Describe the developments that have allowed advances in neonatal cardiac surgery. 2. Describe the diagnostic approach to hypoplastic left heart syndrome (HLHS). 3. Delineate the preoperative management of the neonate who has HLHS. 4. Describe the original Norwood procedure and subsequent modifications. 5. Delineate the optimal therapy in the postoperative period for neonates who have a single ventricle. Advances in the surgical and medical management of children who have congenital heart disease (CHD) have led to a dramatic improvement in overall survival and reduced the long-term sequelae of open-heart surgery. With improved survival and decreased morbidity over the past 2 decades, the early complete repair of complex congenital heart problems in preterm and low-birthweight neonates has gained wider acceptance. Cardiologists and cardiothoracic surgeons now consider and perform complete neonatal repair more frequently than palliative surgery in this patient population. The treatment of hypoplastic left heart syndrome (HLHS) best illustrates the evolution of management strategies to improve survival and long-term outcome. A recent modification of the Norwood operation that involves a right ventricle-to-pulmonary artery conduit has led to much improved early postoperative stability and, in many centers, improved survival to a stage II superior cavopulmonary connection. A multidisciplinary team approach is required to provide the necessary care for this complex patient population. In 1938, Robert Gross at Children’s Hospital in Boston successfully ligated a patent ductus arteriosus, and this procedure—performed against the wishes of surgeon-in-chief William Ladd—opened the era of surgery for CHD. (1) Gross and Hufnagel performed detailed animal experiments to develop a technique for treatment of coarctation of the aorta that involves excision and end-to-end anastomosis. (2) Clarence Craaford of Stockholm, Sweden, had visited Gross to observe his experimental work, and in October 1944, Craaford and Nylin were the first to repair aortic …

Novel application of 4D sonography with B‐flow imaging and spatio‐temporal image correlation (STIC) in the assessment of the anatomy of pulmonary arteries in fetuses with pulmonary atresia and ventricular septal defect

To assess the reliability of two-dimensional gray-scale (2D) and color Doppler echocardiography in the study of the size and anatomy of the central pulmonary arteries and of the sources of pulmonary blood flow in a case series of fetuses with pulmonary atresia and ventricular septal defect (PA-VSD), and to evaluate whether the use of 4D ultrasound with B-flow imaging and spatio-temporal image correlation (STIC) can improve prenatal diagnostic accuracy. The study population comprised a group of seven PA-VSD fetuses that had been examined by 2D and color Doppler echocardiography exclusively, and a group of five additional cases identified initially by conventional echocardiography and examined further by 4D ultrasound, for all of which a thorough postnatal or autopsy study of the size and anatomy of the pulmonary arteries and blood supply was available. 2D and color Doppler echocardiography failed to assess the anatomy of the central pulmonary arteries and the source of the pulmonary blood supply in 33% and 25% of the 12 cases, respectively. 4D ultrasound with B-flow imaging and STIC assessed successfully the anatomy of the pulmonary arteries and the source of pulmonary blood supply in all five fetuses examined. The prognosis of PA-VSD is influenced by the anatomy of the pulmonary arteries and the sources of the pulmonary blood supply, and by coexisting extracardiac and genetic anomalies. Our findings, although limited to a small sample size, suggest that 4D echocardiography with B-flow imaging and STIC, unlike 2D ultrasound, can provide thorough visualization of very small vessels and of the arterial blood supply to the lungs of fetuses with PA-VSD. 4D ultrasound may be used in the future to improve and help to detail the diagnosis of other fetal cardiac defects.

Risk assessment and early outcome following the Norwood procedure for hypoplastic left heart syndrome

This study was undertaken to identify risk factors for early mortality following the Norwood procedure for hypoplastic left heart syndrome (HLHS) and develop a predictive risk model to monitor clinical performance. Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure at a single institution. The early mortality was 29% (n=95). Estimated early mortality improved progressively and was 10% at the end of the series. Multivariable analysis identified that body surface area at operation, size of the ascending aorta, preoperative right ventricular function and source of pulmonary blood flow established at operation were risk factors for early mortality (P<0.05). These variables were included in a preoperative risk model. The duration of cardiopulmonary support was an independent risk factor, which was included in a separate operative risk model. The performance of the risk models was evaluated by goodness-of-fit analyses, using the Hosmer-Lemeshow test and receiver operating characteristic (ROC) curve. Both models were well calibrated across all deciles (P=0.64, P=0.77) and discriminated moderately well. The area under the ROC curve was 0.71 for Model 1 and 0.75 for Model 2. Risk adjustment broadly accounted for the variation in early mortality observed during this series. Patient-related and predetermined operative variables have a major influence on the early outcome following the Norwood procedure for HLHS. The identification of these risk factors allows the risk of early mortality to be calculated. This information could be applied as part of a risk-adjusted performance-monitoring system to enable early identification of meaningful changes in practice.

Influence of surgical strategies on outcome after the Norwood procedure

The study objective was to identify how the evolution of surgical strategies influenced the outcome after the Norwood procedure. From 1992 to 2004, 367 patients underwent the Norwood procedure (median age, 4 days). Three surgical strategies were identified on the basis of arch reconstruction and source of pulmonary blood flow. The arch was refashioned without extra material in group A (n = 148). The arch was reconstructed with a pulmonary artery homograft patch in groups B (n = 145) and C (n = 74). Pulmonary blood flow was supplied by a modified Blalock-Taussig shunt in groups A and B. Pulmonary blood flow was supplied by a right ventricle to pulmonary artery conduit in group C. Early mortality, actuarial survival, and freedom from arch reintervention or pulmonary artery patch augmentation were analyzed. Early mortality was 28% (n = 102). Actuarial survival was 62% +/- 3% at 6 months. Early mortality was lower in group C (15%) than group A (31%) or group B (31%; P <.05). Actuarial survival at 6 months was better in group C (78% +/- 5%) than group A (59% +/- 5%) or group B (58% +/- 4%; P <.05). Fifty-three patients (14%) had arch reintervention. Freedom from arch reintervention was 76% +/- 3% at 1 year, with univariable analysis showing no difference among groups A, B, and C (P =.71). One hundred patients (27%) required subsequent pulmonary artery patch augmentation. Freedom from patch augmentation was 61% +/- 3% at 1 year, and was lower in group C (3% +/- 3%) than group A (80% +/- 4%) or group B (72% +/- 5%; P <.05). Survival after the Norwood procedure improved after the introduction of a right ventricle to pulmonary artery conduit, but a greater proportion of patients required subsequent pulmonary artery patch augmentation. The type of arch reconstruction did not affect the incidence of arch reintervention.

Neonatal Cavopulmonary Assist: Pulsatile Versus Steady-Flow Pulmonary Perfusion

Morbidity and mortality associated with single-ventricle physiology decrease substantially once a systemic venous, rather than systemic arterial, source of pulmonary blood flow is established. Cavopulmonary assist has potential to eliminate critical dependence on the problematic systemic-to-pulmonary shunt as a source of pulmonary blood flow in neonates. We have previously demonstrated feasibility of neonatal cavopulmonary assist under steady-flow conditions. We hypothesized that pulsatile pulmonary perfusion would further improve pulmonary hemodynamics. Lambs (weight 7.2 +/- 1.1 kg, age 7.9 +/- 1.5 days) underwent total cavopulmonary diversion using bicaval venous-to-main pulmonary artery cannulation. A miniature centrifugal pump was used to augment cavopulmonary flow. Pulsatility was created with an intermittently compressed compliance chamber in the circuit. Hemodynamic and gas exchange data were measured for 8 hours. Pulsatile (n = 6), steady-flow (n = 13), and control (n = 6) groups were compared using two-way analysis of variance with repeated measures. All animals remained physiologically stable with normal gas exchange function. Mean pulmonary arterial pressure was elevated in pulsatile and steady-flow groups compared with the control group and within-group baseline values. Pulmonary vascular resistance was elevated initially in both assist groups but decreased significantly over the last 4 hours of the study and normalized after hour 4 in the pulsatile perfusion group. Pulmonary vascular resistance also normalized to control in the steady-flow group after hour 7. Both steady-flow and pulsatile pulmonary perfusion demonstrated normalization of pulmonary vascular resistance to control in a neonatal model of univentricular Fontan circulation. These results suggest that there is no benefit to pulsatile flow in this model.

Twenty-Four Hour Cardiopulmonary Stability in a Model of Assisted Newborn Fontan Circulation

Morbidity and mortality after stage-1 palliation of hypoplastic left heart syndrome is high as a result of adverse physiologic conditions imposed by the systemic-to-pulmonary arterial shunt. Conversion to a systemic venous source of pulmonary blood flow (Glenn/Fontan) substantially decreases instability and mortality risk. Cavopulmonary assist has the potential to eliminate critical dependence on the problematic systemic arterial shunt. We studied this support modality during a 24-hour period in a neonatal animal model of univentricular Fontan circulation. Lambs (8.1 +/- 0.9 kg, 8.3 +/- 2.1 days, n = 7) underwent total cavopulmonary diversion. A miniature centrifugal pump was used to assist cavopulmonary flow. Control animals (6.6 +/- 1.0 kg, 7.3 +/- 2.1 days, n = 11) underwent placement of monitoring lines only. Hemodynamic and gas exchange data were measured. Within-group and between-group comparisons were made using two-way repeated measures analysis of variance. After an initial phase of reactivity, pulmonary vascular resistance returned to low levels and was not significantly different from baseline values after hour 13 or significantly different from control values after hour 4. Systemic venous pressure remained low. Oxygenation and ventilation remained normal with no histologic evidence of parenchymal lung injury. Pump-assisted cavopulmonary diversion is well tolerated up to 24 hours in the neonatal period. Despite initial reactivity, pulmonary vascular resistance trended toward normal and approached control values. Cavopulmonary assist holds the potential to serve as a bridge to neonatal Fontan repair of single ventricle. Chronic studies are warranted to determine the duration and rate of weaning of support to transition to an unassisted univentricular Fontan circulation.

Appropriate Additional Pulmonary Blood Flow at the Bidirectional Glenn Procedure is Useful for Completion of Total Cavopulmonary Connection

The role and effect of additional pulmonary blood flow at the time of bidirectional Glenn procedure (BDG) is controversial. We assessed our experiences to clarify the effects of controlled additional pulmonary blood flow on outcomes after BDG. Thirty-eight patients who underwent BDG (2.1 +/- 2.1 years of age) were enrolled in this study. In group A (n = 29) additional pulmonary blood flow was controlled by the banding of the pulmonary trunk, or the previously created Blalock-Taussig shunt, to keep the central venous pressure equal to or less than 16 mm Hg at BDG. In group B (n = 9), BDG was the only source of pulmonary blood flow. One operative death occurred in group B. In group A, 24 patients underwent total cavopulmonary connection (TCPC) 14 +/- 6 months after BDG, and the remaining 5 patients are waiting for TCPC in good condition. In group B, 6 patients underwent TCPC 8 +/- 7 months after BDG. One patient is awaiting TCPC and the remaining patient is considered unsuitable for TCPC. Cardiac catheterization performed in 32 patients showed significant decrease of pulmonary artery (Nakata) index from 307 +/- 73 to 215 +/- 45 mm2/m2 after BDG in group B (p < 0.05). On the other hand, the Nakata index stayed in higher range from 316 +/- 115 to 287 +/- 74 mm2/m2 in group A, and there was a significant correlation between the Nakata index and the percentage of its difference (Y = 40.823 - 0.144 X; n = 26, R = 0.740, p < 0.0001). Appropriate additional pulmonary blood flow is useful for the completion of TCPC by means of suppressing the decrease in the size of the pulmonary artery, especially in patients with underdeveloped pulmonary arteries.