Hemodynamics and arteriovenous malformations in cavopulmonary anastomosis: The case for residual antegrade pulsatile flow

Does leaving native antegrade pulmonary blood flow at the time of the superior cavopulmonary connection impact long-term outcomes after the Fontan?

Objectives

Antegrade pulmonary blood flow (APBF) may be left or eliminated at the time of the superior cavopulmonary connection (SCPC). Our aim was to assess the impact of leaving native APBF at the SCPC on long-term Fontan outcomes.

Methods

In the Australia and New Zealand Fontan Registry (1985-2021), 587 patients had pre-existing native APBF at the SCPC. At the SCPC, 302 patients had APBF eliminated (APBF-) and 285 patients had APBF maintained (APBF+). The incidence of Fontan failure (composite end point of Fontan takedown, transplant, plastic bronchitis, protein losing enteropathy and death) and atrioventricular (AV) valve repair/replacement post SCPC was compared between the 2 groups.

Results

Sex, predominant-ventricle morphology, isomerism, primary diagnosis, and age/type of Fontan were similar between groups. APBF- versus APBF+ had a higher incidence of arch obstruction/coarctation (17% vs 7%) and previous pulmonary artery band (54% vs 45%) and a lower rate of Fontan fenestration (27% vs 41%). The risk of Fontan failure was similar between the 2 groups (hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.58-1.78; P = .96). The risk of AV-valve repair/replacement was greater in APBF+ versus APBF- (HR, 2.32; CI, 1.13-4.75; P = .022). The risk of AV-valve repair/replacement remained after adjustment for arch obstruction/coarctation, previous pulmonary artery band and Fontan fenestration (HR, 2.27; CI, 1.07-4.81; P = .033).

Conclusions

Maintaining APBF at the time of the SCPC does not impact the risk of Fontan failure but may increase the incidence of AV-valve repair and/or replacement post-SCPC.

In Silico Evaluation of a Self-powered Venous Ejector Pump for Fontan Patients

PURPOSE

The Fontan circulation carries a dismal prognosis in the long term due to its peculiar physiology and lack of a subpulmonic ventricle. Although it is multifactorial, elevated IVC pressure is accepted to be the primary cause of Fontan's high mortality and morbidity. This study presents a self-powered venous ejector pump (VEP) that can be used to lower the high IVC venous pressure in single-ventricle patients.

METHODS

A self-powered venous assist device that exploits the high-energy aortic flow to lower IVC pressure is designed. The proposed design is clinically feasible, simple in structure, and is powered intracorporeally. The device's performance in reducing IVC pressure is assessed by conducting comprehensive computational fluid dynamics simulations in idealized total cavopulmonary connections with different offsets. The device was finally applied to complex 3D reconstructed patient-specific TCPC models to validate its performance.

RESULTS

The assist device provided a significant IVC pressure drop of more than 3.2 mm Hg in both idealized and patient-specific geometries, while maintaining a high systemic oxygen saturation of more than 90%. The simulations revealed no significant caval pressure rise (< 0.1 mm Hg) and sufficient systemic oxygen saturation (> 84%) in the event of device failure, demonstrating its fail-safe feature.

CONCLUSIONS

A self-powered venous assist with promising in silico performance in improving Fontan hemodynamics is proposed. Due to its passive nature, the device has the potential to provide palliation for the growing population of patients with failing Fontan.

Pulmonary Arteriovenous Fistulae After Fontan Operation: Incidence, Clinical Characteristics, and Impact on All-Cause Mortality

BACKGROUND

The Fontan operation is a surgical procedure used in children with univentricular hearts. Pulmonary arteriovenous fistulae (PAVF) is a major complication after a Fontan operation. However, the incidence and related clinical pathophysiology of PAVF remain unclear.

PURPOSE

This study aimed to clarify the incidence of PAVF, its clinical characteristics, and its influence on all-cause mortality.

METHODS AND RESULTS

We serially assessed the presence of PAVF using pulmonary artery angiography and/or contrast echocardiography during catheterization in 391 consecutive patients who underwent the Fontan procedure and compared the results with the Fontan pathophysiology and all-cause mortality. PAVF developed in 36 patients (9.2%), including 30 diffuse- and six discrete-PAVF types. The PAVF-free rates at 1, 5, 10, 15, 20, and ≥25 years after Fontan operation were 97, 96, 93, 88, 87, and 83%, respectively. The mean arterial blood oxygen saturation (SaO₂) in patients with diffuse PAVF at each corresponding postoperative stage were 90, 91, 91, 91, 89, and 88%, respectively, indicating lower SaO₂ levels than those in patients without PAVF (all p < 0.01). However, there was no difference in the SaO₂ levels between patients with discrete PAVF and those without PAVF. During a median follow-up period of 2.9 years after the last catheterization, 31 patients, including 12 patients with PAVF, died. Patients with PAVF, especially those with diffuse PAVF, had a higher mortality rate (p = 0.01) than those without PAVF (hazard ratio: 3.6, 95% confidence interval: 1.6-7.8, p = 0.0026).

CONCLUSION

Patients who underwent Fontan surgery had an increased incidence of PAVF as they aged. Discrete PAVF did not influence SaO₂ or mortality, whereas the presence of diffuse PAVF caused hypoxia and was associated with all-cause mortality.

Pulmonary vascular disease in Fontan circulation-is there a rationale for pulmonary vasodilator therapies?

The Fontan circulation is a palliative concept for patients with univentricular hearts. The central veins are connected directly to the pulmonary arteries (cavo-pulmonary connection) to separate the pulmonary and the systemic circulation. There is no sub-pulmonary ventricle that generates pressure to drive blood through the pulmonary arteries. Pulmonary blood flow is determined by central venous pressure (CVP) and pulmonary vascular resistance (PVR). The capability of the Fontan circulation to compensate for alterations in PVR is limited, as CVP can only be increased within narrow ranges without adverse clinical consequences. Consequently, systemic ventricular preload and cardiac output are dependent on a healthy lung with low PVR. Failure of the Fontan circulation is relatively common. In addition to ventricular dysfunction, maladaptive pulmonary vascular remodeling resulting in increased pulmonary resistance may play a key role. The pathophysiology of the maladaptive vascular processes remains largely unclear and diagnosis of an increased PVR is challenging in Fontan circulation as accurate measurement of pulmonary arterial blood flow is difficult. In the absence of a sub-pulmonary ventricle, pulmonary artery pressure will almost never reach the threshold conventionally used to define pulmonary arterial hypertension. There is a need for markers of pulmonary vascular disease complementary to invasive hemodynamic data in Fontan patients. In order to treat or prevent failure of the Fontan circulation, pathophysiological considerations support the use of pulmonary vasodilators to augment pulmonary blood flow and systemic ventricular preload and lower CVP. However, to date the available trial data have neither yielded enough evidence to support routine use of pulmonary vasodilators in every Fontan patient nor have they been helpful in defining subgroups of patients that might benefit from such therapies. This review discusses potential pathomechanisms of pulmonary vascular disease; it summarizes the current knowledge of the effects and efficacy of pulmonary vasodilator therapy in Fontan patients and tries to outline areas of potential future research on the diagnosis and treatment of pulmonary vascular disease and Fontan failure.

One and One-Half Ventricle Repair: Role for Restricting Antegrade Pulmonary Blood Flow

BACKGROUND

In patients with hypoplastic subpulmonary ventricles, the one and one-half ventricle (1.5V) repair is an alternative to the Fontan procedure. However, in 1.5V-treated patients with pulsatile pulmonary blood flow, superior vena cava (SVC) hypertension or right atrial hypertension may develop. This study aimed to (1) describe patient outcomes after 1.5V repair and (2) determine whether pulmonary artery septation at 1.5V repair confers a lower risk of SVC or right atrial hypertension.

METHODS

This study retrospectively reviewed patients who underwent a 1.5V repair between 1989 and 2020. The primary outcome was transplant-free survival. Secondary outcomes were postoperative SVC hypertension (defined by mean Glenn pressures greater than 17 mm Hg, SVC flow reversal or pulsatility, venovenous collateral vessels, or SVC syndrome) and right atrial hypertension (defined as mean right atrial pressures greater than 10 mm Hg with inferior vena cava and hepatic vein dilation or flow reversal).

RESULTS

A total of 74 patients underwent 1.5V repair at a median age of 29.6 months (interquartile range, 8.9 to 45.5 months). Median follow-up time was 39.9 months (interquartile range, 11.4 to 178.1 months). Transplant-free survival at 10 years was 92.4%. Among survivors, 12% (8 of 69) had right atrial hypertension and 39% (27 of 69) had SVC hypertension on follow-up. Survivors with unseptated pulmonary arteries had a greater risk of SVC hypertension compared with patients with septated pulmonary arteries (44% vs 10%; P = .04). No difference was found in right atrial hypertension between the 2 groups.

CONCLUSIONS

Patients with 1.5V repair avoid Fontan-associated complications with favorable transplant-free survival. However, SVC hypertension remains a significant long-term complication. Pulmonary artery septation at 1.5V repair may reduce the risk of SVC hypertension.

Left Ventricular Recruitment in Patients With Hypoplastic Left Heart Syndrome

Hypoplastic left heart complex with "borderline left ventricle" and intact ventricular septum is a clinical conundrum for the congenital heart surgeon. The choice between neonatal biventricular repair and single ventricle palliation can be challenging, and the current tools to aid in the decision-making process fail to account for the morbidity associated with intermediate and late diastolic dysfunction. Staged ventricular recruitment, consisting of valvular repair techniques, resection of endocardial fibroelastosis, atrial septal restriction, and augmentation of pulmonary blood flow, has been shown to improve left ventricular size and function culminating in eventual biventricular circulation. Despite staged ventricular recruitment, some patients cannot undergo biventricular conversion. Strategies to address these complex patients, including the "reverse" double switch, are the next frontier in biventricular repair.

Post-Fontan pulmonary artery growth in patients with a bidirectional cavopulmonary shunt with additional antegrade pulsatile blood flow

Background

Patients with antegrade pulmonary blood flow after a bidirectional cavopulmonary shunt (Glenn) may have better pulmonary artery growth. This study evaluated pulmonary artery growth in patients with and without prior additional pulsatile antegrade flow in a Glenn shunt at midterm follow-up after a Fontan procedure.

Methods

We reviewed 212 patients who had single-ventricle palliation in a 10-year period;103 (33 in pulsatile group 1 and 70 in nonpulsatile group 2) were selected for analysis. Data on demographics, procedures, perioperative course, and midterm follow-up after the Fontan procedure were compared. Echocardiography data were collected. Pulmonary artery sizes measured at cardiac catheterization and follow-up echocardiograms were used to calculate the Nakata index.

Results

Perioperative details were comparable in both groups, mean pulmonary artery pressure and systemic oxygen saturations were higher in group 1 compared to group 2. Venovenous collaterals were increased in group 1. There was a significant difference in the pre-Fontan and follow-up Nakata index between groups. There was a significant increase in the Nakata index in group 1 between the pre-Glenn and pre-Fontan assessments as well as the Nakata index between the pre-Fontan and midterm follow-up. There was no significant change in the Nakata index in group 2 between assessments.

Conclusions

A pulsatile Glenn shunt is associated with better pulmonary artery growth which continues long after the additional pulsatile flow is eliminated. It is possible that the effects of anterograde pulmonary blood flow on pulmonary artery growth in early life continue long after the Fontan completion.

Proceedings From the 2019 Stanford Single Ventricle Scientific Summit: Advancing Science for Single Ventricle Patients: From Discovery to Clinical Applications

Because of remarkable advances in survival over the past 40 years, the worldwide population of individuals with single ventricle heart disease living with Fontan circulation has grown to ≈70 000, with nearly half aged >18 years. Survival to at least 30 years of age is now achievable for 75% of Fontan patients. On the other hand, single ventricle patients account for the largest group of the 6000 to 8000 children hospitalized with circulation failure, with or without heart failure annually in the United States, with the highest in‐hospital mortality. Because there is little understanding of the underlying mechanisms of heart failure, arrhythmias, pulmonary and lymphatic vascular abnormalities, and other morbidities, there are no specific treatments to maintain long‐term myocardial performance or to optimize overall patient outcomes.

Pulmonary Vasodilator Therapy in Children with Single Ventricle Physiology: Effects on Saturation and Pulmonary Arterial Pressure

In children with single ventricle physiology, increased pulmonary vascular resistance may impede surgical progression or result in failing single ventricle physiology. The use of pulmonary vasodilators has been suggested as a potential therapy. However, knowledge on indication, dosage, and effect is limited. A retrospective case notes review of all (n = 36) children with single ventricle physiology, treated with pulmonary vasodilators by the UK Pulmonary Hypertension Service for Children 2004-2017. Therapy was initiated in Stage 1 (n = 12), Glenn (n = 8), or TCPC (n = 16). Treatment indications were high mean pulmonary arterial pressure, cyanosis, reduced exercise tolerance, protein-losing enteropathy, ascites, or plastic bronchitis. Average dose of sildenafil was 2.0 mg/kg/day and bosentan was 3.3 mg/kg/day. 56% had combination therapy. Therapy was associated with a reduction of the mean pulmonary arterial pressure from 19 to 14 mmHg (n = 17, p < 0.01). Initial therapy with one or two vasodilators was associated with an increase in the mean saturation from 80 to 85%, (n = 16, p < 0.01). Adding a second vasodilator did not give significant additional effect. 5 of 12 patients progressed from Stage 1 to Glenn, Kawashima, or TCPC, and 2 of 8 from Glenn to TCPC during a mean follow-up time of 4.7 years (0-12.8). Bosentan was discontinued in 57% and sildenafil in 14% of treated patients and saturations remained stable. Pulmonary vasodilator therapy was well tolerated and associated with improvements in saturation and mean pulmonary arterial pressure in children with single ventricle physiology. It appears safe to discontinue when no clear benefit is observed.

Pulmonary arteriovenous malformations in a patient with single ventricle and polysplenia syndrome

A 5-month-old girl with single ventricle, interrupted inferior vena cava and polysplenia syndrome palliated with bilateral Blalock-Taussig shunts developed severe cyanosis despite apparently increased pulmonary blood flow. Angiography revealed diffuse pulmonary arteriolar capillary dilatation and early pulmonary venous filling, suggesting the presence of pulmonary arteriovenous malformations. Abdominal angiography at 6 months demonstrated a large extrahepatic portosystemic shunt, which was percutaneously closed with a vascular plug. Kawashima operation was performed 2 weeks after portosystemic shunt closure. Although cyanosis improved temporarily, the patient suffered from deteriorating cyanosis at 9 months of age and underwent Fontan completion. Thereafter, her oxygen saturation gradually improved to 95% over the course of 3 weeks. Both the congenital extrahepatic portosystemic shunt and Kawashima operation contributed to the development of pulmonary arteriovenous malformations.

Endothelin-1 may play an important role in the Fontan circulation

OBJECTIVES

Our goal was to evaluate whether endothlin-1 (ET-1) plays an important role in the Fontan circulation.

METHODS

Thirteen patients with single-ventricle physiology (Glenn circulation, n = 7; Fontan circulation, n = 6) were evaluated using lung histopathological and immunohistochemical studies and then compared with the normal autopsied controls without congenital heart disease (n = 13). We evaluated the medial thickness of the small pulmonary arteries. For 10 of these patients, quantitative real-time polymerase chain reaction analyses of ET-1, endothelin receptors Type A and Type B, endothelin-converting enzyme-1 and endothelial nitric oxide synthase were performed.

RESULTS

The medial thickness of the small pulmonary arteries in patients with single-ventricle physiology was greater than that of those in the control group (P = 0.0341). Severe medial hypertrophy of the pulmonary arteries was observed in patients who had poor outcomes. Immunohistochemical studies revealed that the marked expression of ET-1 was observed in the endothelium and media of their pulmonary arteries. In these patients, the messenger RNA expression of ET-1 was also increased. Two patients showed high levels of expression of ETAR and ETBR, although these 2 cases maintain good Fontan circulation.

CONCLUSIONS

Medial hypertrophy and the overexpression of ET-1 in the pulmonary arteries were observed in some patients in whom the Fontan circulation failed. Our data suggest that ET-1 may play an important role in maintaining the Fontan circulation.

Is the Hepatic Factor a miRNA that Maintains the Integrity of Pulmonary Microvasculature by Inhibiting the Vascular Endothelial Growth Factor?

Background:

The “hepatic factor,” a molecule or group of molecules present in the hepatic venous blood, essential for the prevention of the development of pulmonary arteriovenous malfor-mations (PAVMs) and right-to-left shunting has been a conceptual enigma in the understanding of many related conditions.

Methods:

Patients with various forms of liver diseases including acute hepatic failure, and others with normal hepatic function like hereditary hemorrhagic telangiectasia (HHT), inflammatory and parasitic disorders, cardiogenic hepatopulmonary syndrome (cHPS) and skin disorders like Dyskeratosis con-genita are all known to cause PAVMs. Over a period of the last two decades our understanding of the pathogenesis of PAVMs has changed, but the mechanisms are still not clearly understood. The pres-ence of PAVMs once considered a contraindication for liver transplantation is now a cure for PAVMs in patients with HPS.

Results:

In this article the molecular mechanisms and the underlying pathogenesis of PAVMs are dis-cussed and the role of microRNA (miRNA) in its pathogenesis is favorably argued. Identifying and preventing or treating the underlying mechanisms will significantly influence the management of a large group of patients who at present cannot be effectively treated with a very poor prognosis. Progressive polycythemia, desaturation, stroke, and infection are serious complications of PAVMs.

Conclusion:

The clinical data and current understanding leads to the possible role of miRNA, which inhibits Vascular Endothelial Growth Factor (VEGF) synthesis as a pathogenic mechanism for the development of PAVMs.

Early to mid-term results after total cavopulmonary connection performed in the second decade of life

OBJECTIVES

Total cavopulmonary connection (TCPC) performed in the second decade of life has rarely been studied. Thus, we investigated (bicentric study) early and late morbidity and mortality following completion of TCPC in these patients.

METHODS

From January 1999 to June 2014, 63 patients (14.5 ± 2.9 years) underwent TCPC (extracardiac conduit). Palliation before completion was an isolated bidirectional cavopulmonary shunt (BCPS) in 3 patients or BCPS associated with additional pulmonary blood flow (APBF) that was either antegrade (Group 1) in 38 (63%) or retrograde (Group 2) in 22 (37%). Preoperative and perioperative data were reviewed retrospectively.

RESULTS

Mean pulmonary arterial and ventricular end-diastolic pressures were 12.2 and 9.2 mmHg, respectively. Mean Nakata index was 279 ± 123 and 228 ± 87 mm 2 /m 2 in Groups 1 and 2, respectively ( P  =   0.01). Aortic cross-clamping was performed in 22 from Group 1 and 8 from Group 2 ( P  =   0.04). Mean follow-up was 4.57 years [0.8-15]. Nine patients had prolonged stays in the intensive care unit (>6 days). There were 1 early and 2 late deaths (non-cardiac related). Actuarial survival was 96% at 4 years. At last follow-up, single-ventricle function remained normal or improved in all patients (Group 1) compared to 82% in Group 2 ( P  =   0.02). New York Heart Association (NYHA) class had improved in both groups: 47 patients were NYHA class II and 16 class III preoperatively vs 50 class I and 10 class II postoperatively ( P  <   0.001).

CONCLUSIONS

Single-ventricle palliation with BCPS and APBF allowed completion of TCPC in the second decade of life, with encouraging mid-term results. However, BCPS with retrograde APBF was associated with single-ventricle dysfunction: thus, this technique needs to be used cautiously as long-lasting palliation.

Bidirectional cavopulmonary anastomosis with additional pulmonary blood flow: good or bad pre-Fontan strategy

Objectives

This study aimed to evaluate the influence of preserved additional pulmonary blood flow (APBF) on survival after bidirectional cavopulmonary shunt (BCPS) and completion of Fontan circulation.

Methods

From March 2003 and April 2015, 156 patients with a single ventricle underwent BCPS. After performing propensity score analysis (1:1) for the entire sample, 50 patients with APBF (APBF group) were matched with 50 patients without APBF (no-APBF group).

Results

Age ( P  = 0.90), sex ( P  = 0.57), weight ( P  = 0.75), single ventricle morphology ( P =  0.87), type of neonatal palliative procedure ( P =  0.52), saturation ( P =  0.35), ejection fraction ( P =  0.90), Nakata index ( P  = 0.70) and mean pulmonary artery pressure ( P  = 0.72) were not significantly different between the groups. No significant survival difference was demonstrated ( P  = 0.54). One and 4-year survival rates were both 89.1% ± 4.6% in the APBF group and 87.2% ± 4.9% and 83.4% ± 5.9%, respectively, in the no-APBF group. There was no significant difference in rates of Fontan completion ( P  = 0.24), which was achieved in 22 patients from the APBF group (55.0%) and 26 patients from the no-APBF group (65.0%). However, Fontan completion occurred significantly earlier in the no-APBF group ( P  < 0.01). In this group, Fontan procedure was performed before 36 months of inter-stage period in 45.9% ± 8.5% of cases (95% CI 31.0-63.7%) compared to only 13.3 ± 5.6% (95% CI 5.8-29.1%) in the APBF group.

Conclusions

Our study demonstrates that APBF does not affect survival after BCPS or Fontan completion rate. APBF allows postponing the Fontan procedure without a negative effect on clinical status.

Current outcomes of the bi-directional cavopulmonary anastomosis in single ventricle patients: analysis of risk factors for morbidity and mortality, and suitability for Fontan completion

OBJECTIVES

The bi-directional cavopulmonary anastomosis forms an essential staging procedure for univentricular hearts. This review aims to identify risk factors for morbidity, mortality, and suitability for Fontan completion.

METHODS

A total of 114 patients undergoing cavopulmonary anastomosis between 1992 and 2012 were reviewed to assess primary - mortality and survival to Fontan completion - and secondary outcome endpoints - re-intubation, new drain, and ICU stay. Median age and weight were 8 months and 6.9 kg, respectively. In 83% of patients, 1-3 interventions had preceded. Norwood-type procedures became more prevalent over time.

RESULTS

Extubation occurred after a median of 4 hours, median ICU stay was 2 days; 10 patients (8.8%) needed re-intubation and 18 received a new drain. Higher central venous pressure and transpulmonary gradient were risk factors for new drain insertion (p<0.01). Higher pre-operative pulmonary pressure correlated with increased inotropic support and prolonged intubation (p=0.01). Need for re-intubation was significantly affected by younger age at operation (p=0.01). Hospital and pre-Fontan mortality were 11.4 and 5.3%, respectively. Operative mortality was independently affected by younger age (p=0.013), lower weight (p=0.02), longer bypass time (p=0.04), and re-intubation (p=0.004). Interstage mortality was mainly influenced by moderate ventricular function (p=0.03); 82% of survivors underwent or are candidates for Fontan completion.

CONCLUSION

The cavopulmonary anastomosis remains associated with adverse outcomes. Age at operation decreases with rising prevalence of complex univentricular hearts. Considering the important impact of re-intubation on hospital mortality, peri-operative management should focus on optimising cardio-respiratory status. Once this selection step is taken, successful Fontan completion can be expected, provided that ventricular function is maintained.

Decision-Making for Surgery in the Management of Patients with Univentricular Heart

A series of technical refinements over the past 30 years, in combination with advances in perioperative management, have resulted in dramatic improvements in the survival of patients with univentricular heart. While the goal of single-ventricle palliation remains unchanged - normalization of the pressure and volume loads on the systemic ventricle, the strategies to achieve that goal have become more diverse. Optimal palliation relies on a thorough understanding of the changing physiology over the first years of life and the risks and consequences of each palliative strategy. This review describes how to optimize surgical decision-making in univentricular patients based on a current understanding of anatomy, physiology, and surgical palliation.

Does the persistence of pulsatile antegrade pulmonary blood flow following bidirectional Glenn procedure affect long term outcome?

OBJECTIVES

To evaluate outcomes of the Glenn procedure with or without pulsatile antegrade pulmonary blood flow during palliation of patients with functionally single ventricles.

METHODS

The clinical records of 111 consecutive patients who underwent a bidirectional Glenn procedure for palliation of single ventricle morphologies at our institution between 1997 and 2010 were reviewed. We specifically excluded infants with the diagnosis of hypoplastic left heart syndrome. Following the Glenn procedure, there were 57 patients (Group 1) with and 54 (Group 2) without antegrade pulmonary blood flow. We reviewed their long term data from our database to determine whether the presence of forward flow after the Glenn procedure affected outcome.

RESULTS

There was 1 early hospital death (in Group 1). The mean SaO2 at discharge was higher in Group 1 (83%±2 vs 78%±4; P<0.001). There was no difference in duration of chest drain insertion, length of intensive care and hospital stay between the two groups. The median follow-up time was 7.1 years (range, 1.7-14.9 years). Sixty-five patients underwent Fontan completion (35 from Group 1) a median of 3.6 years (Group 1) and 3.3 (Group 2) after the Glenn procedure. Three patients died following Fontan completion (1 from Group 1). The 5- and 10-year survival (95% CI) was 96% (84-98%) and 96% (84-98%) in Group 1, and 88% (74-94%) and 82% (66-91%) in Group 2, respectively (log-rank; P=0.03). There was no significant difference in SaO2 levels, or incidence of systemic atrioventricular valve regurgitation or ventricular dysfunction in survivors between groups at the last follow-up.

CONCLUSIONS

We conclude that leaving antegrade flow following a Glenn procedure improves oxygen saturation significantly and while it does not impact on short term outcome or hospital stay, long-term outcome is significantly better.

Pulmonary arteriovenous malformations after the superior cavopulmonary shunt: mechanisms and clinical implications

Children with functional single ventricle heart disease are commonly palliated down a staged clinical pathway toward a Fontan completion procedure (total cavopulmonary connection). The Fontan physiology is fraught with long-term complications associated with lower body systemic venous hypertension, eventually resulting in significant morbidity and mortality. The bidirectional Glenn shunt or superior cavopulmonary connection (SCPC) is commonly the transitional stage in single ventricle surgical management and provides excellent palliation. Some studies have demonstrated lower morbidity and mortality with the SCPC when compared with the Fontan. Unfortunately the durability of the SCPC is significantly limited by the development of pulmonary arteriovenous malformations (PAVMs) which have been commonly attributed to the absence of hepatic venous blood flow and the lack of pulsatile flow to the affected lungs. Abnormal angiogenesis has been suggested as a final common pathway to PAVM development. Understanding these fundamental mechanisms through the investigation of angiogenic pathways associated with the pathogenesis of PAVMs would help to develop medical therapies that could prevent or reverse this complication following SCPC. Such therapies could improve the longevity of the SCPC, potentially eliminate or significantly postpone the Fontan completion with its associated complications, and improve long-term survival in children with single ventricle disease.