Extracardiac conduit fontan procedure: early and intermediate results

Comparative effectiveness among thromboprophylaxis strategies after the Fontan operation: A systematic review and network meta-analysis

INTRODUCTION

A variety of thromboprophylaxis regimens have been administered in patients following the Fontan procedure. However, consensus guidelines regarding the optimal thromboprophylaxis strategy have not yet been developed.

METHOD

A network meta-analysis was conducted to evaluate the comparative effectiveness among available thromboprophylaxis regimens and major bleeding events associated with these regimens.

RESULTS

A total of 28 comparative studies with 4430 Fontan patients were included. The incidence of thromboembolic events (TE) was significantly lower in individuals who underwent thromboprophylaxis compared to those who did not. Compared to a no-treatment strategy, nonvitamin K oral anticoagulants (NOACs) showed the largest treatment effect for preventing TE (OR = 0.08, 95 % CI 0.03 to 0.21), followed by warfarin (OR = 0.16, 95 % CI 0.10 to 0.27), and aspirin (OR = 0.23, 95 % CI 0.14 to 0.38). Indeed, NOACs were significantly more effective than aspirin in preventing TE (OR = 0.35, 95 % CI 0.14 to 0.84). Aspirin was associated with the lowest occurrence of major bleeding events, followed by NOACs, no medication, and warfarin. NOACs were shown to possess a highly favorable overall profile.

CONCLUSION

Prescribing thromboprophylaxis drugs, either antiplatelets or anticoagulants, may be more effective in preventing TE after the Fontan operation than not doing so. Among the included regimens, NOACs demonstrated significantly greater efficacy than aspirin; however, they did not show statistically significant superiority over warfarin. Aspirin exhibited lower rates of major bleeding compared to both NOACs and warfarin. Overall, NOACs tended to offer the most advantageous balance of efficacy and safety. However, the findings should be interpreted considering the certainty and limitations of the evidence, including potential residual confounding in observational studies.

Thromboprophylaxis in Patients With Fontan Circulation

BACKGROUND

The optimal strategy for thromboprophylaxis in patients with a Fontan circulation is unknown.

OBJECTIVES

The aim of this study was to compare the efficacy and safety of aspirin, warfarin, and nonvitamin K oral anticoagulants (NOACs) in a network meta-analysis.

METHODS

Relevant studies published by February 2022 were included. The primary efficacy outcome was thromboembolic events; major bleeding was a secondary safety outcome. Frequentist network meta-analyses were conducted to estimate the incidence rate ratios (IRRs) of both outcomes. Ranking of treatments was performed based on probability (P) score.

RESULTS

A total of 21 studies were included (26,546 patient-years). When compared with no thromboprophylaxis, NOAC (IRR: 0.11; 95% CI: 0.03-0.40), warfarin (IRR: 0.23; 95% CI: 0.14-0.37), and aspirin (IRR: 0.24; 95% CI: 0.15-0.39) were all associated with significantly lower rates of thromboembolic events. However, the network meta-analysis revealed no significant differences in the rates of major bleeding (NOAC: IRR: 1.45 [95% CI: 0.28-7.43]; warfarin: IRR: 1.38 [95% CI: 0.41-4.69]; and aspirin: IRR: 0.72 [95% CI: 0.20-2.58]). Rankings, which simultaneously analyze competing interventions, suggested that NOACs have the highest P score to prevent thromboembolic events (P score 0.921), followed by warfarin (P score 0.582), aspirin (P score 0.498), and no thromboprophylaxis (P score 0.001). Aspirin tended to have the most favorable overall profile.

CONCLUSIONS

Aspirin, warfarin, and NOAC are associated with lower risk of thromboembolic events. Recognizing the limited number of patients and heterogeneity of studies using NOACs, the results support the safety and efficacy of NOACs in patients with a Fontan circulation.

Fontan procedure on deep hypothermic circulatory arrest: Short-term results and technique

Background

Various operative strategies are described for the Fontan procedure. In this study, we describe our short-term results and technique of Fontan procedure on cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA).

Methods

This was a retrospective study of 32 patients, median age of 6 years (4-19 years) and median weight of 20 kg (13-51 kg), who underwent Fontan procedure on CPB and DHCA from July 2016 to July 2021.

Results

The median CPB time was 125 min (77-186 min), the median DHCA time was 42 min (27-50 min), and the median Fontan pressure was 14 mmHg (10-18 mmHg). The median time to extubation was 4 h (1-20 h), the duration of chest tube drainage was 8 days (5-24 days), and the median intensive care unit stay was 4 days (3-8 days). The presence of heterotaxy was associated with longer duration of pleural drainage (P = 0.01). There was no operative mortality and no major adverse events such as seizures, gross neurological deficits, or arrhythmias in the postoperative period.

Conclusions

Fontan procedure can be safely performed on CPB and DHCA with good operative results. This operative strategy may be used in special circumstances like in patients with situs and systemic venous anomalies and those requiring repair of a complex intracardiac defect. Long-term follow-up will be required to evaluate if this strategy has any impact on the neurodevelopmental outcome and the long-term sequelae of Fontan.

Tissue engineering: Relevance to neonatal congenital heart disease

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential. Tissue engineering has shown promise in providing new solutions for pediatric CHD patients through the development of tissue engineered vascular grafts, heart patches, and heart valves. In this review, we examine the current surgical treatments for congenital heart disease and the research being conducted to create tissue engineered products for these patients. While much research remains to be done before tissue engineering becomes a mainstay of clinical treatment for CHD patients, developments have been progressing rapidly towards translation of tissue engineering devices to the clinic.

Semi-Automatic Planning and Three-Dimensional Electrospinning of Patient-Specific Grafts for Fontan Surgery

This paper proposes a semi-automatic Fontan surgery planning method for designing and manufacturing hemodynamically optimized patient-specific grafts. Fontan surgery is a palliative procedure for patients with a single ventricle heart defect by creating a new path using a vascular graft for the deoxygenated blood to be directed to the lungs, bypassing the heart. However, designing patient-specific grafts with optimized hemodynamic performance is a complex task due to the variety of patient-specific anatomies, confined surgical planning space, and the requirement of simultaneously considering multiple design criteria for vascular graft optimization. To address these challenges, we used parameterized Fontan pathways to explore patient-specific vascular graft design spaces and search for optimal solutions by formulating a nonlinear constrained optimization problem, which minimizes indexed power loss (iPL) of the Fontan model by constraining hepatic flow distribution (HFD), percentage of abnormal wall shear stress (%WSS) and geometric interference between Fontan pathways and the heart models (InDep) within clinically acceptable thresholds. Gaussian process regression was employed to build surrogate models of the hemodynamic parameters as well as InDep and [Formula: see text] (conduit model smoothness indicator) for optimization by pattern search. We tested the proposed method on two patient-specific models (n=2). The results showed the automatically optimized (AutoOpt) Fontan models hemodynamically outperformed or at least are comparable to manually optimized Fontan models with significantly reduced surgical planning time (15 hours versus over 2 weeks). We also demonstrated feasibility of manufacturing the AutoOpt Fontan conduits by using electrospun nanofibers.

Late outcomes after the Fontan procedure in patients with single ventricle: a meta-analysis

OBJECTIVE

More patients with Fontan physiology are reaching adulthood. The purpose of this meta-analysis was to evaluate the late outcomes of patients palliated with Fontan procedure and to assess the risk factors for mortality.

METHODS

PubMed, Embase and Web of Science were queried to retrieve observational studies of survival in patients following the Fontan procedure with ≥5 years of follow-up. A random-effects model was used to determine pooled survival estimates at 5, 10 and 15 years. Meta-regression was used to assess potential moderators for death.

RESULTS

Nineteen articles with a total of 5859 patients were included. The weighted mean follow-up time was 8.94±2.64 years with overall 8.3% deaths and 1.5% transplants. Pooled survival estimates at 5, 10 and 15 years were 90.7%, 87.2% and 87.5%, respectively; and 88.4%, 85.7% and 84.1%, respectively, for studies that included all three time intervals (n=4). Earliest surgical year included in the study, proportion of atriopulmonary connections versus extracardiac conduit or lateral tunnel, and older age at Fontan were associated with higher rates of death, but ventricular morphology was not. Protein-losing enteropathy, reoperation and pacemaker insertion were reported in 2.1%, 5.6% and 6.8% patients, respectively.

CONCLUSIONS

Survival following the Fontan procedure has improved with time and is influenced by Fontan type and age at the time of Fontan. At a mean follow-up of 8.9 years, there was no significant association between survival and ventricular morphology, not taking into account the mortality prior to Fontan.

Life After Surviving Fontan Surgery: A Meta-Analysis of the Incidence and Predictors of Late Death

AIM

We now know that 20-40% of patients with a single ventricle will develop heart failure after the second decade post-Fontan surgery. However, we remain unable to risk-stratify the cohort to identify patients at highest risk of late failure and death. We conducted a systematic review of all reported late outcomes for patients with a Fontan circulation to identify predictors of late death.

METHODS

We searched MEDLINE, Embase and PubMed with subject terms ("single ventricle", "Hypoplastic left heart syndrome", "congenital heart defects" or "Fontan procedure") AND ("heart failure", "post-operative complications", "death", "cause of death", "transplantation" or "follow-up studies") for relevant studies between January 1990 and December 2015. Variables identified as significant predictors of late death on multivariate analysis were collated for meta-analysis. Survival data was extrapolated from Kaplan-Meier survival curves to generate a distribution-free summary survival curve.

RESULTS

Thirty-four relevant publications were identified, with a total of 7536 patients included in the analysis. Mean follow-up duration was 114 months (range 24-269 months). There were 688 (11%) late deaths. Predominant causes of death were late Fontan failure (34%), sudden death (19%) and perioperative death (16%). Estimated mean survival at 5, 10 and 20 years post Fontan surgery were 95% (95%CI 93-96), 91% (95%CI 89-93) and 82% (95%CI 77-85). Significant predictors of late death include prolonged pleural effusions post Fontan surgery (HR1.18, 95%CI 1.09-1.29, p<0.001), protein losing enteropathy (HR2.19, 95%CI 1.69-2.84, p<0.001), increased ventricular end diastolic volume (HR1.03 per 10ml/BSA increase, 95%CI 1.02-1.05, p<0.001) and having a permanent pacemaker (HR12.63, 95%CI 6.17-25.86, p<0.001).

CONCLUSIONS

Over 80% of patients who survive Fontan surgery will be alive at 20 years. Developing late sequelae including protein losing enteropathy, ventricular dysfunction or requiring a pacemaker predict a higher risk of late death.

The Long-Term Management of Children and Adults with a Fontan Circulation: A Systematic Review and Survey of Current Practice in Australia and New Zealand

Although long-term survival is now the norm, Fontan patients face significant morbidity and premature mortality. Wide variation exists in long-term Fontan management. With an aim of improving their long-term management, we conducted a systematic review to identify best available evidence and gaps in knowledge for future research focus. We also surveyed cardiologists in Australia and New Zealand managing Fontan patients, to determine the alignment of current local practice with best available evidence. A systematic review was conducted using strict search criteria (PRISMA guidelines), pertaining to long-term Fontan management. All adult congenital and paediatric cardiologists registered with The Australia and New Zealand Fontan Registry were invited to respond to an online survey. Reasonable quality evidence exists for non-inferiority of aspirin over warfarin for thromboprophylaxis in standard-risk Fontan patients. No strong evidence is currently available for the routine use of ACE inhibitors, beta blockers or pulmonary vasodilators. Little evidence exists regarding optimal arrhythmia treatment, exercise restriction/prescription, routine fenestration closure, elective Fontan conversion and screening/management of liver abnormalities. Although pregnancy is generally well tolerated, there are high rates of miscarriage and premature delivery. Thirty-nine out of 78 (50 %) cardiologists responded to the survey. Heterogeneity in response was demonstrated with regard to long-term anti-coagulation, other medication use, fenestration closure and pregnancy and contraception counselling. Substantial gaps in our knowledge remain with regard to the long-term management of Fontan patients. This is reflected in the survey of cardiologists managing these patients. We have identified a number of key areas for future research.

Strategies for thromboprophylaxis in Fontan circulation: a meta-analysis

BACKGROUND

The Fontan circulation is associated with an increased risk of thromboembolic events (TEs). As many as 25% of these thrombotic events result in fatality. More subtle adverse effects on the pulmonary circulation from embolic thrombi may further impair adequate functioning of the circuit. Despite these well-documented phenomena, the most optimal approaches to thromboprophylaxis are still not clearly defined.

OBJECTIVE

A meta-analysis of published trials in English on PubMed and Cochrane libraries that evaluated the role of using TE prophylaxis in patients who underwent the Fontan procedure was conducted.

METHODS

10 studies with a total number of 1200 patients with an average follow-up time of 7.1 years were identified. A random effect model was used.

RESULTS

The incidence of TE was significantly less in patients who received TE prophylaxis (using either aspirin or warfarin) compared with patients who did not receive TE prophylaxis (OR 0.425, 95% CI 0.194 to 0.929, p<0.01, I(2)=37%). The incidence of TE was significantly lower in patients who received aspirin compared with no TE prophylaxis (OR 0.363, 95% CI 0.177 to 0.744, p<0.01, I(2)=0%) and who received warfarin compared with no TE prophylaxis (OR 0.327, 95% CI 0.168 to 0.634, p<0.01, I(2)=2.5%). There was no significant difference in incidence of TE between warfarin and aspirin (OR 0.936, 95% CI 0.609 to 1.438, p=0.54, I(2)=0%). Furthermore, there was no significant difference in incidence of early TE (within 6 months of the operation) or late TE (>6 months) between patients receiving warfarin and aspirin (OR 0.784, 95% CI 0.310 to 1.982, p=0.37, I(2)=8%) and (OR 0.776, 95% CI 0.249 to 2.42, p=0.3, I(2)=45%), respectively. When only total cavopulmonary connection patients were included, there was again no difference between warfarin and aspirin in the incidence of TE (OR 0.813, 95% CI 0.471 to 1.401, p=0.34, I(2)=11%).

CONCLUSIONS

This study shows a significantly lower incidence of TE after Fontan procedure if either aspirin or warfarin is used. This meta-analysis suggests no significant difference in incidence of early or late TE in patients receiving aspirin compared with warfarin.

Challenges in the management of patients with functionally univentricular heart in Turkey

Management of patients with functionally univentricular heart encompasses a wide array of developments over the years in every country. This article describes our working group experiences and 30-year story of single ventricle surgery in Turkey. Diagnosis, surgical treatment, and medical treatment of this complex group of patients necessitate courageous and continuous team effort with multi-institutional collaboration.

Antiplatelet versus anticoagulation therapy after extracardiac conduit Fontan: a systematic review and meta-analysis

The benefits of prophylactic anticoagulation or antiplatelet therapy for patients undergoing extracardiac conduit (ECC) Fontan procedure still are a matter of debate. Through a systematic review and meta-analysis, this study aimed to determine the incidence of thromboembolism among patients undergoing ECC Fontan who received anticoagulation or antiplatelet therapy. Until February 2010, MEDLINE studies describing the incidence of thromboembolic events after ECC Fontan were reviewed. Information on type of drugs and clinical outcome was extracted. The 20 studies analyzed involved 1,075 patients: 220 (20.4%) in the antiplatelet group and 855 (79.5%) in the anticoagulation group. The mean follow-up period ranged from 2 to 144 months. The overall thromboembolism rate was 5.2% (95% confidence interval [CI], 3.8-7%; I(2) = 0%; p(het) = 0.32). The effect of different therapeutic strategies on the occurrence of thromboembolic and bleeding events was analyzed. Interestingly, the anticoagulation therapy compared with the antiplatelet therapy was not associated with a significant reduction in the incidence of overall thromboembolic complications (5% vs 4.5%, respectively; I(2) = 0%; p(het) = 0.80). Only two cases of bleeding were observed among patients receiving anticoagulant therapy at the time of the event. For patients undergoing ECC Fontan, the rate of thromboembolic and bleeding events associated with antiplatelet therapy is similar to that associated with anticoagulation therapy.

Extracardiac Fontan Operation after Late Bidirectional Glenn Shunt

The outcomes of 33 consecutive extracardiac Fontan operations performed between 1999 and 2008 in patients who mostly had initial Glenn shunts beyond infancy were reviewed. Preoperatively, the median oxygen saturation was 76.2% and mean pulmonary artery pressure was 10.5 mm Hg. The median age was 4.1 years at Glenn shunt procedure and 10 years at Fontan operation. The duration of chest tube drainage was longer in these patients than in series where Glenn shunts were created at a younger age. All patients received warfarin for 1 year, then warfarin and/or aspirin. At follow-up (median, 14 months), there was no significant ventricular dysfunction. Median oxygen saturation at the last follow-up was 92%. All patients in sinus rhythm preoperatively continued in this status. There was no Fontan failure or mortality. All patients were in New York Heart Association class I or II, although objective cardiopulmonary exercise evaluation in 8 patients showed impaired exercise tolerance. Despite a trend towards prolonged pleural effusion, there was no adverse outcome in the short or intermediate term. Long-term follow-up is required to see whether delayed creation of a Glenn shunt is associated with late disadvantages.

Factors Influencing Survival in Patients after Bidirectional Glenn Shunt

Clinical characteristics, echocardiographic values, and catheterization data of 45 patients with a functional univentricular heart who had a bidirectional Glenn shunt instituted between November 1994 and October 2006 were retrospectively reviewed. Median age at operation was 20 months (range, 9 months to 19 years). Median follow-up time after the bidirectional Glenn operation was 4 years (range, 1 day to 11 years). The early mortality rate was 4/45 (8.9%); overall mortality was 24.4%. Actuarial survival after a bidirectional Glenn shunt was 73% ± 8% at 5 years and 55% ± 17% at 10 years. In multivariate Cox proportional hazards analysis, heterotaxy syndrome and systemic right ventricle were independent predictors of mortality after the bidirectional Glenn shunt. Age at operation, oxygen saturation, previous surgery, a pulsatile Glenn shunt, cardiopulmonary bypass, postoperative pulmonary artery pressure, bilateral superior venae cavae, and Nakata index were not predictive of mortality. The presence of heterotaxy syndrome and systemic right ventricle in patients with a functional univentricular heart should lead to aggressive investigation and management strategies.

Follow-up and physical activity in postoperative congenital heart disease

During the past three decades, interventional cardiology and cardiac surgery have found solutions even for the most complex congenital heart malformations with an overall low operative mortality. A careful clinical and instrumental follow-up of postoperative congenital heart disease patients is fundamental not only to prevent complications and/or to treat eventual residua and sequelae, but also to modify future surgical strategies on the basis of long-term results. To be able to give a correct prognostic meaning to the data collected during the follow-up, the cardiologist should have an excellent knowledge of the native defect, the surgical technique and the post-surgical anatomy and physiology. Major cardiological concerns during a follow-up after corrective surgery are: arrhythmias; heart failure; cyanosis and erythrocytosis; and infective endocarditis. Psychosocial needs, such as employment, contraception, pregnancy and physical exercise, are very important to enable a 'normal' life, complying with the postoperative hemodynamic situation of the patients.

The impact of altitude on early outcome following the Fontan operation

BACKGROUND

The success of a Fontan circulation depends on several factors including low pulmonary vascular resistance. Pulmonary vascular resistance rises in response to hypoxia. Hypoxia is associated with altitude. Therefore, we wondered whether altitude is a risk factor for early failure after the Fontan operation. The aim was to test this hypothesis.

METHODS

Data were obtained from all published series of 'total cavopulmonary' Fontan operations since 1990. The early failure rate from each series and the altitude of the respective cities were recorded. Early failure was defined as death, takedown of Fontan, or transplantation during the same hospital admission. The association between altitude and failure rate was investigated by rank correlation and logistic regression.

RESULTS

24 series were identified from centres situated at altitudes ranging from sea level to 520 metres. The plot of failure rate versus altitude suggests that failure rate increases with altitude. Logistic regression did not fit the data adequately. This was possibly due to the influence of unmeasured and unknown factors affecting the results, as well as the fact that centres were not randomly chosen but were self-selected by virtue of publishing their results. However, Spearman's rank correlation was 0.74 (p = 0.001).

CONCLUSION

The early outcome of the Fontan circulation appears to be adversely affected by altitude.

The New York Heart Association Classes and functional status: What are we really measuring?

The New York Heart Association (NYHA) Classes are used to appraise the status of patients with heart disease and evaluate treatment outcomes in clinical and research settings. Ambiguity exists concerning the construct the Classes represent and the optimal way to capture and interpret the information. This article examines the NYHA Classes within the context of a published functional status framework by Leidy. The framework proposes that (1) physiological indicators provide information on capacity, (2) physical activity characterizes performance, and (3) symptoms accompanying activity offer insight into reserve. It is proposed that the NYHA Classes provide a summary statement of both the reduction in reserve accompanying a decline in capacity and the concomitant increase in capacity utilization required to maintain performance in patients with heart disease. This premise is illustrated quantitatively through secondary analysis of data from 22 patients with ischemic heart disease and left ventricular dysfunction.

Total Cavopulmonary Connection Flow With Functional Left Pulmonary Artery Stenosis

BACKGROUND

In our multicenter study of the total cavopulmonary connection (TCPC), a cohort of patients with long-segment left pulmonary artery (LPA) stenosis was observed (35%). The clinically recognized detrimental effects of LPA stenosis motivated a computational fluid dynamic simulation study within 3-dimensional patient-specific and idealized TCPC pathways. The goal of this study was to quantify and evaluate the hemodynamic impact of LPA stenosis and to judge interventional strategies aimed at treating it.

METHODS AND RESULTS

Simulations were conducted at equal vascular lung resistance, modeling both discrete stenosis (DS) and diffuse long-segment hypoplasia with varying degrees of obstruction (0% to 80%). Models having fenestrations of 2 to 6 mm and atrium pressures of 4 to 14 mm Hg were explored. A patient-specific, extracardiac TCPC with 85% DS was studied in its original configuration and after virtual surgery that dilated the LPA to 0% stenosis in the computer medium. Performance indices improved exponentially (R2>0.99) with decreasing obstruction. Diffuse long-segment hypoplasia was approximately 50% more severe with regard to lung perfusion and cardiac energy loss than DS. Virtual angioplasty performed on the 3-dimensional Fontan anatomy exhibiting an 85% DS stenosis produced a 61% increase in left lung perfusion and a 50% decrease in cardiac energy dissipation. After 4-mm fenestration, TCPC baffle pressure dropped by approximately 10% and left lung perfusion decreased by approximately 8% compared with the 80% DS case.

CONCLUSIONS

DS <60% and diffuse long-segment hypoplasia <40% could be considered tolerable because both resulted in only a 12% decrease in left lung perfusion. In contrast to angioplasty, a fenestration (right-to-left shunt) reduced TCPC pressure at the cost of decreased left and right lung perfusion. These results suggest that pre-Fontan computational fluid dynamic simulation may be valuable for determining both the hemodynamic significance of LPA stenosis and the potential benefits of intervention.

Physics-Driven CFD Modeling of Complex Anatomical Cardiovascular Flows?A TCPC Case Study

Recent developments in medical image acquisition combined with the latest advancements in numerical methods for solving the Navier-Stokes equations have created unprecedented opportunities for developing simple and reliable computational fluid dynamics (CFD) tools for meeting patient-specific surgical planning objectives. However, for CFD to reach its full potential and gain the trust and confidence of medical practitioners, physics-driven numerical modeling is required. This study reports on the experience gained from an ongoing integrated CFD modeling effort aimed at developing an advanced numerical simulation tool capable of accurately predicting flow characteristics in an anatomically correct total cavopulmonary connection (TCPC). An anatomical intra-atrial TCPC model is reconstructed from a stack of magnetic resonance (MR) images acquired in vivo. An exact replica of the computational geometry was built using transparent rapid prototyping. Following the same approach as in earlier studies on idealized models, flow structures, pressure drops, and energy losses were assessed both numerically and experimentally, then compared. Numerical studies were performed with both a first-order accurate commercial software and a recently developed, second-order accurate, in-house flow solver. The commercial CFD model could, with reasonable accuracy, capture global flow quantities of interest such as control volume power losses and pressure drops and time-averaged flow patterns. However, for steady inflow conditions, both flow visualization experiments and particle image velocimetry (PIV) measurements revealed unsteady, complex, and highly 3D flow structures, which could not be captured by this numerical model with the available computational resources and additional modeling efforts that are described. Preliminary time-accurate computations with the in-house flow solver were shown to capture for the first time these complex flow features and yielded solutions in good agreement with the experimental observations. Flow fields obtained were similar for the studied total cardiac output range (1-3 1/min); however hydrodynamic power loss increased dramatically with increasing cardiac output, suggesting significant energy demand at exercise conditions. The simulation of cardiovascular flows poses a formidable challenge to even the most advanced CFD tools currently available. A successful prediction requires a two-pronged, physics-based approach, which integrates high-resolution CFD tools and high-resolution laboratory measurements.

A novel implantation technique for closure of an atypical fenestration connecting the right atrial appendage to an extracardiac conduit by use of a 15 mm Helex device in a patient with total cavopulmonary connection

We report on a 7-years old patient after total cavopulmonary anastomosis with an extracardiac conduit. An atypical fenestration was created during the operation connecting the right atrial appendage to the extracardiac conduit. Because of arterial desaturation, the fenestration connecting the anterior wall of the extracardiac conduit to the posterior wall of the right atrial appendage was successfully occluded with a 15 mm Helex device by use of a modified implantation technique.

Midterm surgical results of total cavopulmonary connection: clinical advantages of the extracardiac conduit method

OBJECTIVE

We evaluated the midterm surgical outcomes of intra-atrial lateral tunnel and extracardiac conduit total cavopulmonary connection to clarify the clinical superiority.

METHODS

Patients (n = 167) underwent total cavopulmonary connection (88 with lateral tunnel and 79 with extracardiac conduit) from November 1991 to March 1999. Survival, incidence of reoperation and late complications, exercise tolerance, hemodynamic variables, and plasma concentration of natriuretic peptide type A were compared. In the lateral tunnel group, time-related change in lateral tunnel size was investigated for its relationship to postoperative arrhythmias.

RESULTS

The 8-year survival was 93.2% in the lateral tunnel group and 94.9% in the extracardiac conduit group. Seven reoperations were performed in the lateral tunnel group but none in the extracardiac conduit group. Supraventricular arrhythmias developed in 14 patients (15.9%) in the lateral tunnel group and in 4 patients (5.1%) in the extracardiac conduit group (P =.003). Freedom from cardiac-related events was 72.5% in the lateral tunnel group and 89.8% in the extracardiac conduit group at 8 years (P =.0098). Hemodynamic variables and exercise tolerance were similar in both groups but plasma natriuretic peptide type A concentration, a parameter of atrial wall tension, was higher in the lateral tunnel group. In the lateral tunnel group, intra-atrial tunnel size increased by 19.4% during the 44.2-month interval and the percent increase in tunnel size was an independent predictor of supraventricular arrhythmias.

CONCLUSIONS

The midterm survival, hemodynamic variables, and exercise tolerance were similar and satisfactory in both lateral tunnel and extracardiac conduit groups; however, the incidence of cardiac-related events was significantly less frequent in the extracardiac conduit group. In the lateral tunnel group, careful observation is required to monitor the relationship of the dilating tendency of the intra-atrial tunnel and the development of late complications.

Thromboembolic problems after the Fontan operation

One of the major causes of morbidity and mortality after the Fontan operation is thromboembolic events (TE). To assess the current knowledge of TE after Fontan surgery, a comprehensive MEDLINE search of the English literature from 1971 to 2000 was conducted using the key words Fontan, univentricular heart, children, thrombosis, congenital heart disease, cavopulmonary, and palliation. Other relevant publications were identified from bibliographies of the literature retrieved. Fifty-one studies were identified and analyzed for incidence, potential morbidity and mortality, risk factors, prophylactic options, and risk/benefit ratio of prophylactic anticoagulation as relates to TE after Fontan surgery. There were 23 case reports, 13 retrospective cohort studies that included some details about TE among other reported outcomes after Fontan procedures, eight retrospective cohort studies in which TE was the primary outcome measure, and seven articles reporting cross-sectional point surveys, only three of which directly surveyed TE as an outcome. Based on an analysis of the current literature, there is insufficient evidence to make clear recommendations about optimal anticoagulant prophylaxis at this time. Multicenter randomized controlled trials comparing prophylactic antiplatelet with anticoagulation therapies are needed to provide rational scientific guidelines for future management of Fontan patients.

Lateral tunnel versus extracardiac conduit fontan procedure: a concurrent comparison

BACKGROUND

The aim of this study was to compare the outcomes of the lateral tunnel (LT) and extracardiac conduit (ECC) Fontan procedures at a single institution over the same time period.

METHODS

From November 1995 through October 2002, 70 Fontan procedures were performed: 37 LT and 33 ECC. All were fenestrated; 96% were staged with a prior superior cavopulmonary connection. Compared with the ECC patients, the LT patients were younger (2.7 +/- 1.1 vs 3.9 +/- 2.5 years; p = 0.01), had a higher incidence of hypoplastic left heart syndrome (57% vs 21%; p < 0.01), and a longer aortic cross-clamp time (55 +/- 13 vs 26 +/- 15 min; p < 0.01). Weight, gender, preoperative cardiac catheterization values, and cardiopulmonary bypass time did not differ between the two groups.

RESULTS

Operative mortality was 2.8%, 1 patient in each group (p = 1.0). Over the first 24 hours following operation the mean Fontan pressure, transpulmonary gradient, and common atrial pressure did not differ between LT and ECC patients. The median duration of mechanical ventilation (LT 12 vs ECC 18 hours), intensive care unit stay (LT 2 vs ECC 3 days), chest tube drainage (LT 10 vs ECC 8 days), and hospital stay (LT 11 vs ECC 12 days) did not differ. The ECC patients had a higher incidence of sinus node dysfunction both in the postoperative period (27% vs LT 8%; p = 0.09), and persisting at hospital discharge (10% vs LT 0%; p = 0.02). Mean follow-up was 3.6 +/- 1.6 years in LT, and 3.0 +/- 2.2 years in ECC patients (p = 0.2). There was one late death. Actuarial survival at 5 years is 97% for LT, and 91% for ECC patients (p = 0.4); 96% of patients are in NYHA class I, and 4% in class II, with no difference between groups. Sinus node dysfunction was seen during follow-up in 15% LT vs 28% ECC patients (p = 0.2).

CONCLUSIONS

The LT and ECC approaches had comparable early and mid-term outcomes, including operative morbidity and mortality, postoperative hemodynamics, resource use, and mid-term survival and functional status. ECC patients had a higher incidence of sinus node dysfunction early after operation.

Left innominate vein-pulmonary artery shunt with Glenn anastomosis in a Fontan candidate with central pulmonary artery stenosis

Heart failure developed 9 years after Fontan takedown with systemic-pulmonary artery shunt in a 12-year-old girl with pulmonary atresia, intact ventricular septum, and obstruction in the proximal pulmonary artery. Surgical scar after multiple operations complicated direct repair of the pulmonary artery, and thus she was not eligible for definitive palliation. Left innominate vein-to-left pulmonary artery shunt using an expanded polytetrafluoroethylene conduit in association with Glenn anastomosis functionally established an unobstructive superior cavopulmonary connection without direct repair of the central pulmonary artery, later facilitating one and a half ventricle repair. Use of an extraanatomical shunt may functionally relieve central pulmonary artery obstruction in candidates for Fontan-like circulation.

Incisional atrial reentrant tachycardia: experimental study on the conduction property through the isthmus

BACKGROUND

Incisional atrial reentrant tachycardia is a life-threatening tachyarrhythmia after surgery for congenital heart disease. Slow conduction through an isthmus between anatomical barriers, such as a right atriotomy or the sites for cannulation, has been shown to be a prerequisite for perpetuation of the incisional atrial reentrant tachycardia. However, the conduction property through the isthmus has not been examined in detail.

METHODS

To examine the conduction property, 2 tandem incisions were made on the lateral right atrium with various distances (3 to 20 mm) between the incisions in 16 canines. Four weeks after the surgery, the lateral right atrium was mapped epicardially during pacing to examine the conduction property through the isthmus. The conduction property was characterized by approximated curves of the conduction velocity through the isthmus in accordance with the pacing cycle lengths. The atrial tissue at the isthmus was examined microscopically.

RESULTS

The approximated curves of the conduction velocity were classified into 3 different types. Decremental conduction was observed only in the isthmi between 5 and 15 mm in width. A small amount of surviving myocardium between the scars formed the critical isthmus microscopically (decremental type). In the isthmi wider than 15 mm in width, slow conduction was not seen at any paced cycle length (nondecremental type). In the extremely narrow isthmi less than 5 mm in width, all of the atrial myocardium at the isthmus was replaced by fibrous tissue. Conduction was blocked at the isthmus and the activation detoured around the incisions (block type). There was a statistically significant difference in the approximated curves between the 3 different types of conduction properties (P <.01).

CONCLUSION

The width of the isthmus determines the conduction property through the isthmus that contributes to the development of the incisional atrial reentrant tachycardia. Thus, the incisional atrial reentrant tachycardia may be preventable by leaving a sufficient amount of surviving myocardium between the incisions or by connecting the incisions by an ablative procedure.

Sinus node dysfunction after Fontan modifications--influence of surgical method

BACKGROUND

Sinus node dysfunction (SND) is reported to be a troublesome complication following various types of Fontan operations. The correlation of post-Fontan SND with surgical methods was evaluated in this study.

METHODS

By reviewing the medical records, surface ECGs, and Holter monitoring, the range of heart rate (HR) and the risk of SND at intermediate term after Fontan type operation (follow up: 41.3+/-13.1 months) were analyzed between two age matched groups of patients, consisting of the extracardiac conduit group (EC, n=33) and the lateral tunneling group (LT, n=35).

RESULTS

Junctional rhythm was observed in nine out of 35 patients in LT and five out of 33 patients in EC during the follow-up period. Resting HR was faster in EC than that in LT (108+/-15 vs. 82+/-21, P<0.001). Average and maximal HR in Holter monitoring were also faster in EC than those in LT. SND was found in 13 cases (10 in LT, three in EC) during follow-up and one required pacemaker implantation. In the case of situs solitus heart, SND was less frequent in EC than in LT (0/16 vs. 8/26, P=0.01). In the case of heterotaxy syndrome, SND occurred in similar number of cases (3/17 vs. 2/9). The staged approach to Fontan completion did not influence SND. LT repair was the only factor causing sinus node dysfunction according to multivariate logistic regression (P=0.03, OR 5.96).

CONCLUSIONS

Lateral tunnel type surgical repair was more likely to lead to the development of sinus node dysfunction than extracardiac conduit operation. In the case of heterotaxy syndrome, surgical method had no significant influence.

Validity and reliability of the NYHA classes for measuring research outcomes in patients with cardiac disease

The New York Heart Association (NYHA) functional classification system was developed to help physicians in clinical practice evaluate the effect of cardiac symptoms on a patient's daily activities. Over time, the role of the NYHA classification system has expanded, and it is now frequently used in clinical research. This review of the literature was undertaken to explore whether the NYHA classes have sufficient validity and reliability to serve as a functional outcome measure in research studies. After exploring its strengths and limitations, we conclude that the NYHA classes are a valid measure of functional status, a concept that is distinct from functional capacity and functional performance. The reproducibility of the NYHA functional classification system has not been established in the literature. Researchers are urged to report the methods for determining NYHA class, the training of raters, and the intra-rater or inter-rater reliability in studies that have multiple raters or measurements. Until the reliability of the NYHA functional classification system is determined, it is prudent to refrain from using the NYHA classes as the sole outcome measure of change in function in research studies of cardiac patients.

Modified extracardiac Fontan in a patient with separate hepatic venous drainage

We describe an alternative technique to the extracardiac Fontan procedure in a patient with a univentricular heart, in which the inferior caval vein and the hepatic vein drained separately into the common atrium and the intraatrial orifice of the hepatic vein was adjacent to the opening of the left lower pulmonary vein.