Lateral Tunnel Procedure Research Articles

Adolescents and adults with Fontan circulation: insights from the PREpArE-Fontan registry.

The Patient Registry for Adolescents and Adults with Stable Fontan Circulation aims to describe a contemporary cohort of Fontan patients who could be eligible for a clinical trial investigating macitentan, an endothelin receptor antagonist. This international, non-interventional, multicentre, cross-sectional, observational registry enrolled patients with "stable" Fontan circulation ≥10 years following extra-cardiac conduit or lateral tunnel procedure. Main exclusion criteria were NYHA functional class IV, reoperation of Fontan circulation, or signs of disease worsening. Patient characteristics at enrolment are described; available data were collected during a single registration visit. Of the 266 screened patients, 254 were included in this analysis. At enrolment, median (interquartile range) age was 24 (20;30) years, 37%/63% of patients were from the USA/Europe, 54% were male, 54%/47% had undergone extra-cardiac conduit/lateral tunnel procedures, and 95% were in NYHA functional class I or II. History of arrhythmia was more common in older patients and patients with lateral tunnel; overall prevalence was 19%. Most laboratory values were within the normal range but mean creatinine clearance was abnormally low (87.7 ml/min). Angiotensin-converting enzyme inhibitors were used by 48% of patients and their use was associated with creatinine clearance <90 ml/min (p = 0.007), as was Fontan completion at an older age (p = 0.007). 53.4% of patients had clinical characteristics that could potentially meet an endothelin receptor antagonist trial's eligibility criteria. The PREpArE-Fontan registry describes a cohort of patients who could potentially participate in an endothelin receptor antagonist trial and identified early subtle signs of Fontan failure, even in "stable" patients.

Relation of Fontan Baffle Stroke Volume to Fontan Failure and Lower Exercise Capacity in Patients With an Atriopulmonary Fontan

Fontan failure remains a significant problem, especially in patients with an atriopulmonary Fontan. Fontan baffle volume change during the cardiac cycle (Fontan baffle stroke volume) may affect outcomes in Fontan circulation. Assuming that increased Fontan baffle stroke volume is associated with increased energy loss in the baffle, we hypothesized that higher baffle stroke volume is associated with worse exercise capacity and increased incidence of Fontan failure. Patients from 6 centers with an atriopulmonary or lateral tunnel Fontan operation were included if they had a cardiac magnetic resonance (CMR) study and an adequate cardiopulmonary exercise test. Fontan baffle stroke volume was defined as the difference between maximum and minimum Fontan baffle volumes. Fontan failure was defined as death, listing for transplantation, heart failure symptoms requiring medications, or peak VO2 below 16 ml/kg/min. The study group consisted of 107 patients (median age 19 years, interquartile range, 14 to 29 years). Most patients (84%) had lateral tunnel procedure. During a median follow-up period of 6.8 [interquartile range: 3.2 to 8.8] years after the CMR, 25 (23%) patients had Fontan failure (7 deaths, 3 listed for transplantation, and 15 with heart failure symptoms). Predictors of Fontan failure on multivariable analysis were ventricular tachycardia, protein losing enteropathy, and additionally in atriopulmonary Fontan only, larger Fontan baffle stroke volume. Predictors of lower peak VO2 on multivariable analysis were older age at CMR and additionally in atriopulmonary Fontan only, larger Fontan baffle stroke volume. In conclusion, larger Fontan baffle stroke volume was independently associated with lower peak VO2 and Fontan failure in atriopulmonary Fontan.

Twenty-Five Year Outcomes of the Lateral Tunnel Fontan Procedure

The objective of this study was to characterize late outcomes of the lateral tunnel (LT) Fontan procedure. The outcomes of all patients who underwent an LT Fontan procedure in Australia and in New Zealand were analyzed. Original files were reviewed and outcomes data were obtained through a binational registry. Between 1980 and 2014, a total of 301 patients underwent an LT Fontan procedure across 6 major centers. There were 13 hospital mortalities, 21 late deaths, 8 Fontan conversions and revisions, 8 Fontan takedowns, and 4 heart transplantations. Overall survival at 15 and 25 years was 90% (95% confidence interval [CI]: 86%-93%) and 80% (95% CI: 69%-91%), respectively. Protein-losing enteropathy or plastic bronchitis was observed in 14 patients (5%). Freedom from late failure at 15 and 25 years was 88% (95% CI: 84%-92%) and 82% (95% CI: 76%-87%), respectively. Independent predictors of late Fontan failure were prolonged pleural effusions post Fontan operations (hazard ratio [HR] 3.06, 1.05-8.95, P = 0.041), age >7 years at Fontan (vs 3-5 years, HR 9.7, 2.46-38.21, P = 0.001) and development of supraventricular tachycardia (HR 4.67, 2.07-10.58, P < 0.001). Freedom from tachy- or bradyarrhythmias at 10 and 20 years was 87% (95% CI: 83%-91%) and 72% (95% CI: 66%-79%), respectively. Thromboembolic events occurred in 45 patients (16%, 26 strokes), and freedom from symptomatic thromboembolism at 10 and 20 years was 93% (95% CI: 89%-96%) and 80% (95% CI: 74%-86%), respectively. Over a 25-year period, the LT technique has achieved excellent late survival. As this population ages, it is at an increasing risk of failure and adverse events. We are likely to see an increasing proportion requiring heart transplantation and late reintervention.

The Fontan epidemic: Population projections from the Australia and New Zealand Fontan Registry

BackgroundThe number and age demographic of the future Fontan population is unknown. MethodsPopulation projections were calculated probabilistically using microsimulation. Mortality hazard rates for each Fontan recipient were calculated from survivorship of 1353 Fontan recipients in the Australia and New Zealand Fontan Registry, based on Fontan type, age at Fontan, gender and morphology. Projected rates of new Fontan procedures were generated from historical rates of Fontan procedures per population births. ResultsAt the end of 2014, the living Fontan population of Australia and New Zealand was 1265 people from an Australian and New Zealand regional population of 28 million (4.5 per 100,000 population). Of those, 165 (13%) received an atrio-pulmonary (AP) procedure, 262 (21%) a lateral tunnel (LT) procedure and 838 (66%) an extra-cardiac conduit (ECC) procedure. This population is expected to grow to 1917 (95% CI: 1846: 1986) by 2025 (5.8 per 100,000 population), with 149 (8%) AP procedures, 254 (13%) LT procedures, and 1514 (79%) ECC procedures. By 2045, the living Fontan population is expected to reach 2986 (95% CI: 2877: 3085; 7.2 per 100,000 population). The average age of the Fontan population is expected to increase from 18years in 2014 to 23years (95% CI: 22–23) by 2025, and 31years (95% CI: 30–31) by 2045. ConclusionThe Australian and New Zealand population of patients alive after a Fontan procedure will double over the next 20years increasing the demand for heart-failure services and cardiac transplantation. Greater consideration for the needs of this mostly adult Fontan population will be necessary.

Arrhythmia Management in the Fontan Patient

With longer duration of follow-up, as many as 50% of Fontan patients will develop atrial tachycardia, usually in association with significant hemodynamic abnormalities. Arrhythmia management in the Fontan patient is reviewed. The incidence and type of arrhythmia occurrence are examined, including macro-reentrant rhythm which involves the right atrium, reentrant rhythm localized to the pulmonary venous atrium (seen in patients with lateral tunnel procedures), and atrial fibrillation. Risk factors for development of these arrhythmias are considered, and short- and long-term therapeutic options for medical and surgical treatment are discussed. Surgical results are presented for 117 patients undergoing Fontan conversion and arrhythmia surgery (isthmus ablation (9), modified right atrial maze (38) or Cox-maze III (70)). Operative mortality is low (1/117, 0.8%). Seven late deaths occurred, and include two patients who died shortly following cardiac transplantation (2/6, 33%) after Fontan conversion and arrhythmia surgery. Overall arrhythmia recurrence is 12.8% during a mean follow-up of 56 months. Fontan conversion with arrhythmia surgery can be performed with low operative mortality, low risk of recurrent tachycardia, and marked improvement in functional status in most patients. Because the development of tachycardia is usually an electromechanical problem, attention to only the arrhythmia with medications or ablation may allow progression of hemodynamic abnormalities to either a life-threatening outcome or a point at which transplantation is the only potential option. Because cardiac transplantation in Fontan patients is associated with high early mortality, earlier consideration for surgical intervention is warranted.

New Onset Arrhythmias After the Extracardiac Conduit Fontan Operation Compared With the Intraatrial Lateral Tunnel Procedure: Early and Midterm Results

Background Arrhythmias are one of the main causes of postoperative morbidity superseding Fontan operations. Comparative data on the incidence of sinus node dysfunction after the extracardiac Fontan operation (ECFO) and the intraatrial lateral tunnel Fontan operation (LTFO) are very limited and controversial. The aim of this study was to evaluate whether ECFO decreases the risk of postoperative arrhythmias compared with LTFO. Methods Seventy-four consecutive patients received either an LTFO (n = 29, 5 recordings in 1992 to 9 recordings in 1997) or an ECFO (n = 45, 11 recordings in 1995 to 5 recordings in 2001). The rhythm was documented preoperatively and postoperatively with standard electrocardiogram (ECG) recording and ECG monitoring. During follow-up all patients had 2–8 (median 3) standard ECG recordings per year. Additionally 45 patients (65%) had a Holter ECG at least once a year. Results Median follow-up post-ECFO was 4.4 years (1.6–7.2) and post-LTFO it was 7.9 years (5.4–11.1). There were 5 early deaths (3 LTFO, 2 ECFO) and 1 late death (LTFO) (total mortality 8%). Sinus rhythm persisted in 37 ECFO patients (86%) as compared with 13 LTFO patients (50%) ( p < 0.001). The incidence of new onset supraventricular tachyarrhythmias (SVTs) post-ECFO compared with LTFO was lower: 5 patients (11%) versus 11 patients (38%) early postoperatively ( p < 0.001) and none versus 7 patients (27%) during follow-up ( p < 0.001), respectively. Early postoperatively 10 LTFO patients (34%) and another 3 patients during follow-up required permanent pacemaker implantation due to bradyarrhythmias, but none of the ECFO patients required this. Conclusions Our data suggest that ECFO decreases the incidence of postoperative new onset arrhythmias during early and midterm follow-up compared with LTFO.

Extracardiac total cavopulmonary connection using a tissue-engineered graft

Objective Extracardiac and lateral tunnel total cavopulmonary connection are currently 2 major options for patients with a single ventricle physiology. However, each procedure has some disadvantages over the other. We developed a new technique of extracardiac total cavopulmonary connection using a tissue-engineered graft to overcome some of the disadvantages previously associated with both the extracardiac and lateral tunnel procedures. Methods Between February 2001 and October 2002, 8 patients underwent an extracardiac total cavopulmonary connection using a tissue-engineered graft in our institution. Collected bone marrow cells (1 × 10 8 mononucleocytes) from a patient (∼1-4 mL/kg body weight) were seeded onto a biodegradable scaffold composed of polycaprolactone-polylactic acid copolymer reinforced with woven polylactic acid. After a 2- to 4-hour cultivation, the seeded scaffold was implanted as an extracardiac conduit during the total cavopulmonary connection operation. Results There were no hospital or late deaths. At a mean follow-up of 13.4 months (range 4-25 months), all patients are alive and asymptomatic with no need for repeat surgery. A postoperative catheter examination or computed tomography showed all tissue-engineered grafts to be patent and revealed no stenosis, obstruction, or aneurysmal change in the 8 patients. Conclusion We believe that extracardiac total cavopulmonary connection using a tissue-engineered graft has the potential to overcome some of the disadvantages previously associated with extracardiac or lateral tunnel total cavopulmonary connection. However, an extended follow-up period is required to clarify the long-term clinical outcome for the tissue-engineered graft.

Fluid dynamic comparison of intra-atrial and extracardiac total cavopulmonary connections

Objective: Extracardiac total cavopulmonary connection has recently been introduced as an alternative to intra-atrial procedures. The purpose of this study was to compare the hydrodynamic efficiency of extracardiac and intra-atrial lateral tunnel procedures in total cavopulmonary connections. Methods: Intra-atrial lateral tunnel, extracardiac tunnel, and extracardiac conduit with and without caval vein offset were performed on explanted sheep heart preparations and studied in an in vitro flow loop. A rate of fluid-energy dissipation analysis was performed for each model using simultaneous measurement of pressure and flow at each inlet and outlet of the right side of the heart. Preparations were perfused by using a steady flow blood pump at 4 flow indices (1-6 L/min/m 2) with the inferior vena cava carrying 65% of the total venous return. Results: Fluid-power losses were consistently lower for the extracardiac conduit procedure compared with the two tunnel configurations ( P < .01). A further reduction in energy dissipation of up to 36% was noted in the extracardiac procedure, with 5 mm offset of the extracardiac conduit toward the distal right pulmonary. The intra-atrial and extracardiac tunnel procedures were least efficient, with losses 73% greater than the optimal extracardiac conduit procedure. Conclusions: The extracardiac conduit procedure provides superior hemodynamics compared with the intra-atrial lateral tunnel and extracardiac tunnel techniques. This hydrodynamic advantage is markedly enhanced by the use of conduit–superior vena cava offset, particularly at high physiologic flows that are representative of exercise. These data suggest additional rationale for the use of extracardiac conduit procedures for final-stage completion of the Fontan circulation. (J Thorac Cardiovasc Surg 1999;117:697-704)

Conversion of modified fontan procedure to lateral atrial tunnel cavopulmonary anastomosis

After modified Fontan procedures with atriopulmonary anastomoses or right atrium–right ventricle conduits, some patients have progressive exercise intolerance, effusions, arrhythmias, or protein-losing enteropathy. Theoretic advantages of a lateral atrial tunnel cavopulmonary anastomosis and published clinical results suggest that conversion of other Fontan procedures to the lateral atrial tunnel may afford clinical improvement for some patients. Eight patients (8 to 25 years old) with tricuspid atresia ( n = 4), double-inlet left ventricle ( n = 3), and double-outlet right ventricle ( n = 1) underwent conversion to a lateral tunnel procedure between December 1990 and November 1994. An arbitrary clinical score was assigned before the lateral tunnel procedure and at follow-up. Before conversion, patients had decreased exercise tolerance ( n = 8), arrhythmias ( n = 6), effusions ( n = 4), and protein-losing enteropathy ( n = 8). At catheterization, all had a low cardiac index (1.9 ± 0.7 L•min -1 •m -2 ), five had elevated pulmonary vascular resistance (>3 Wood units), and three had right pulmonary venous return obstruction by compression of an enlarged right atrium. Fenestrated lateral tunnel construction was undertaken 7.3 ± 3.6 years after atriopulmonary anastomosis, with one early death related to low cardiac output. After the lateral tunnel procedure, two patients had no clinical improvement (no change in clinical score) but five patients had either marked or partial improvement. The right pulmonary vein compression present in three patients was resolved after conversion. The mean clinical scores improved from 4.5 ± 1 to 3.0 ± 2 ( p < 0.04). In conclusion, conversion to a lateral tunnel procedure led to clinical improvement in five of eight patients at short-term follow-up and may be particularly indicated for patients with giant right atria or pulmonary vein compression who have symptoms. Pulmonary vein compression should be looked for in patients after modified Fontan procedures and can be relieved by conversion to the lateral tunnel procedure. (J T HORAC C ARDIOVASC S URG 1996;111:1169-76)