Fontan failure: phenotypes, evaluation, management, and future directions

OBJECTIVES

Management of "failing" and "failed" Fontan circulation, particularly the indications, timing, and type of re-intervention, currently remains nebulous. Factors contributing to pathogenesis and mortality following Fontan procedure differ between children and adults.

METHODS

Since organ systems in individual patients are affected differently, we searched the extant literature for a "failing" and "failed" Fontan reviewing the clinical phenotypes, diagnostic modalities, pharmacological, non-pharmacological, and surgical techniques employed, and their outcomes.

RESULTS

A total of 410 investigations were synthesised. Although proper candidate selection, thoughtful technical modifications, timely deployment of mechanical support devices, tissue-engineered conduits, and Fontan takedown have decreased the peri-operative mortality from 9 to 15% and 1 to 3% per cent in recent series, pernicious changes in organ function are causing long-term patient attrition. In the setting of a failed Fontan circulation, literature documents three surgical options: Fontan revision, Fontan conversion, or cardiac transplantation. The reported morbidity of 25% and mortality of 8-10% among Fontan conversion continue to improve in select institutions. While operative mortality following cardiac transplantation for Fontan failure is 30% higher than for other CHDs, there is no difference in long-term survival with actuarial 10-year survival of around 54%. Mechanical circulatory assistance, stem cells, and tissue-engineered Fontan conduit for destination therapy or as a bridge to transplantation are in infancy for failing Fontan circulation.

CONCLUSIONS

An individualised management strategy according to clinical phenotypes may delay the organ damage in patients with a failing Fontan circulation. At present, cardiac transplantation remains the last stage of palliation with gradually improving outcomes.

Efficacy of heart transplantation in patients with a failing Fontan: a systematic review and meta-analysis

Background

As the population of patients with Fontan palliation grows, so does the number of patients with Fontan failure, necessitating heart transplantation. However, due to mainly small-sized studies, outcomes after heart transplantation in these patients remain unclear. The objective of this study was to review the available literature and conduct a meta-analysis to provide well-powered and generalizable estimates of outcomes after heart transplantation in patients with a failing Fontan.

Main text

PubMed, Embase, and MEDLINE databases were searched for original studies of patients with a failing Fontan who underwent heart transplantation. The outcomes included were 1-year and 5-year survival, acute rejection, renal dysfunction, sepsis, and multi-organ failure. Proportions were pooled using random effects models to derive pooled proportions (PPs) and corresponding 95% confidence intervals (CIs). Meta-regression analysis was done to study the effects of age and gender on key outcomes. Sixteen retrospective single-center cohort studies with 426 Fontan patients undergoing heart transplantation were included in this meta-analysis. Pooled analysis of this study further revealed that 1-year survival after heart transplantation was 79.9% ([75.8%, 83.7%]; I2 = 1.92%), and 5-year survival rate was 72.5% ([62.1%, 81.9%]; I2 = 72.12%). Secondary outcomes after heart transplantation of failed Fontan procedure were acute rejection (PP 20% [7.4%, 36.8%]; I2 = 72.48%), renal dysfunction (PP 31.3% [10.5%, 57.2%]; I2 = 75.42%), multi-organ failure (PP 18.6% [2.8 to 43.9%]; I2= 69.60%), and sepsis (PP 21.1% [9%, 36.8%]; I2 = 61.19%).

Conclusion

Cardiac transplantation in patients with a failing Fontan is associated with acceptable interventional success and improved survival rates.

Providing a framework of principles for conceptualising the Fontan circulation

The Fontan operation remains the final palliation for thousands of patients with complex congenital heart disease. By creating a Fontan circuit, control of cardiac output and congestion is wrested away from the ventricle and new haemodynamic forces take control. Understanding how to control the flow in the Fontan circuit will enable clinicians to improve patient management and possibly prevent future complications.

Conclusion

This review proposes a framework of principles to conceptualise the functionality and limitations of a Fontan circulation.

Outcomes of the Non-fenestrated Fontan Procedure at High Altitude

Background:

Although high altitude has been considered a risk factor for the Fontan operation, and an indication for fenestration, there is a paucity of data to support its routine use. Fenestration, with its necessary right to left induced shunt, together with the lower partial pressure of oxygen found with progressive altitude, can significantly decrease hemoglobin oxygen saturation, and therefore, it would be desirable to avoid it.

Objective:

To analyze immediate and medium-term results of the non-fenestrated, extracardiac, Fontan procedure at high altitude.

Methods:

Retrospective analysis of data from consecutive patients who underwent non-fenestrated, extracardiac, Fontan procedure at two institutions located in Mexico City at 2,312 m (7,585 ft) and 2,691 m (8,828 ft) above sea level. High altitude was not considered a risk factor.

Results:

Thirty-nine patients were included, with a mean age of 6.7 years. Mean preoperative indexed pulmonary vascular resistance was 1.7 Wood units. Seventy-nine percent of the patients extubated in the operating room. There was one in-hospital death (2.56%) and one at follow-up. Median chest tube drainage time was 6.5 and 6 days for the right and left pleural spaces. Median oxygen saturation at discharge was 90%. At a median follow-up of six months, all survivors, except one, had good tolerance to daily life activities.

Conclusions:

The present study shows good short- and medium-term results for the non-fenestrated, extracardiac, Fontan operation at altitudes between 2,300 and 2,700 m and might favor this strategy over fenestration to improve postoperative oxygen saturation. Further studies to examine the long-term outcomes of this approach need to be considered.

Single Ventricle Palliation in a Developing Sub-Saharan African Country: What Should be Improved?

Introduction:

Single ventricle physiology management is challenging, especially in low-income countries.

Objective:

To report the palliation outcomes of single ventricle patients in a developing African country.

Methods:

We retrospectively studied 83 consecutive patients subjected to single ventricle palliation in a single center between March 2011 and December 2017. Preoperative data, surgical factors, postoperative results, and survival outcomes were analyzed. The patients were divided by palliation stage: I (pulmonary artery banding [PAB] or Blalock–Taussig shunt [BTS]), II (Glenn procedure), or III (Fontan procedure).

Results:

Of the 83 patients who underwent palliation (stages I-III), 38 deaths were observed (31 after stage I, six after stage II, and one after stage III) for an overall mortality of 45.7%. The main causes of operative mortality were multiple organ dysfunction due to sepsis, shunt occlusion, and cardiogenic shock. Twenty-eight survivors were lost to follow-up (22 after stage I, six after stage II). Thirteen stage II survivors are still waiting for stage III. The mean follow-up was 366 ± 369 days. Five-year survival was 28.4 % for PAB and 30.1% for BTS, while that for stage II and III was 49.8% and 57.1%, respectively. Age (hazard ratio, 0.61; 95% confidence interval: 0.47-0.7; P = .000) and weight at surgery (hazard ratio, 0.45; 95% confidence interval: 0.31-0.64; P = .002) impacted survival.

Conclusion:

A high-mortality rate was observed in this initial experience, mainly in stage I patients. A large number of patients were lost to follow-up. A task force to improve outcomes is urgently required.

Outcomes of the Conversion of the Fontan-Kreutzer Operation to a Total Cavopulmonary Connection for the Failing Univentricular Circulation

Background

The Fontan-Kreutzer procedure (FK) was widely performed in the past, but in the long-term generated many complications resulting in univentricular circulation failure. The conversion to total cavopulmonary connection (TCPC) is one of the options for treatment.

Objective

To evaluate the results of conversion from FK to TCPC.

Methods

A retrospective review of medical records for patients who underwent the conversion of FK to TCPC in the period of 1985 to 2016. Significance p < 0,05.

Results

Fontan-type operations were performed in 420 patients during this period: TCPC was performed in 320, lateral tunnel technique in 82, and FK in 18. Ten cases from the FK group were elected to conversion to TCPC. All patients submitted to Fontan Conversion were included in this study. In nine patients the indication was due to uncontrolled arrhythmia and in one, due to protein-losing enteropathy. Death was observed in the first two cases. The average intensive care unit (ICU) length of stay (LOS) was 13 days, and the average hospital LOS was 37 days. A functional class by New York Heart Association (NYHA) improvement was observed in 80% of the patients in NYHA I or II. Fifty-seven percent of conversions due to arrhythmias had improvement of arrhythmias; four cases are cured.

Conclusions

The conversion is a complex procedure and requires an experienced tertiary hospital to be performed. The conversion has improved the NYHA functional class despite an unsatisfactory resolution of the arrhythmia.