The use of Macitentan in Fontan circulation: a case report

Assessment of exercise capacity using field walking tests in patients after the Fontan procedure: A case-control study

BACKGROUND

Despite the frequent use of the 6-minute walk test (6MWT), exercise capacity has not been assessed with the incremental shuttle walk test (ISWT) in patients who have undergone the Fontan procedure. It is unclear whether these tests cause clinically relevant cardiorespiratory responses in these patients.

OBJECTIVES

We aimed to assess cardiorespiratory responses to the 6MWT and ISWT in Fontan patients, compare the responses with those in the controls, and examine the agreement between the two field tests.

METHODS

Submaximal exercise capacity was assessed using the 6MWT, maximal exercise capacity using the ISWT, quadriceps isometric muscle strength with a hand dynamometer, and body composition using a bioelectrical impedance device.

RESULTS

Twenty-one Fontan patients (16.42±6.63 years, 5F/16M) and 21 controls (16.57±4.30 years, 7F/14M) were included. While body composition was similar between the groups (p>0.05), quadriceps isometric muscle strength and 6MWT and ISWT distance were lower in the Fontan patients than in the controls (p<0.05). In both the 6MWT and ISWT, pre- and post-test heart rate (HR), oxygen saturation (SpO₂), dyspnea, and leg fatigue differed significantly between the Fontan patients and the controls (p<0.05). In addition, the ISWT resulted in a more significant change in HR, SpO₂, and leg fatigue than the 6MWT in the Fontan patients (p<0.05). Bland-Altman plots for the 6MWT vs. the ISWT indicated agreement between the two tests.

CONCLUSION

There were remarkable changes in HR, SpO₂, dyspnea, and leg fatigue in both tests. With similar safety to the 6MWT but with more caution applied for adverse events, the ISWT can also be performed as a field test to evaluate exercise capacity and identify more pronounced exercise-induced responses (especially oxygen desaturation) in Fontan patients.

Macitentan in infants and children with pulmonary hypertensive vascular disease. Feasibility, tolerability and practical issues - a single-centre experience

Macitentan is a safe and effective substance for treatment of adults with pulmonary arterial hypertension. Data on its use in paediatric patients are limited. In this single-centre prospective study, we report on our experience with macitentan in children focusing on applicability and practical aspects. Between December 2014 and July 2018, macitentan was introduced to paediatric patients according to a dosing protocol adjusted to body weight. Blood pressure, heart rate, saturation and clinical symptoms were recorded daily during introduction. Liver function parameters and haemoglobin levels were measured at baseline, four weeks and three months after initiation and after one year of treatment. Twenty-four patients (14 male, 10 female) were enrolled for treatment with macitentan. The mean age was 10.7 ± 7.6 years (range: 0.1 year-23 years). Fifteen out of 24 patients were World Health Organization functional class (FC) II, 7 patients in FC III and 2 patients in FC IV. Twenty out of 24 patients (83%) received additional advanced therapy with sildenafil and/or prostacyclines. We had two early discontinuations because of clinical relevant oedema. In the remaining 22 patients, macitentan was well tolerated. Liver function parameters and blood count levels remained stable during the observational time. The introduction of macitentan was feasible and mostly well tolerated in paediatric patients. Special attention should be paid to oedema during introduction of the drug. To the best of our knowledge, this is the first study to report on its applicability in infants and children. However, larger prospective trials are warranted to verify these preliminary findings.

Fontan failure and the role of pulmonary vasodilator therapy

Background

The Fontan circulation is a palliative procedure for patients born with a single ventricle physiology. The Fontan circulation is associated with significant late morbidity commonly including atrial arrhythmias.

Case presentation

We report a case of an adult Fontan patient who developed protein losing enteropathy (PLE) following persistent atrial arrhythmias. Treatment with a pulmonary vasodilator, sildenafil, resolved the PLE.

Conclusions

The importance of a low pulmonary vascular resistance to maintain wellbeing in the Fontan patient is discussed, as is the role of pulmonary vasodilators.

Heart failure in single right ventricle congenital heart disease: physiological and molecular considerations

Because of remarkable surgical and medical advances over the past several decades, there are growing numbers of infants and children living with single ventricle congenital heart disease (SV), where there is only one functional cardiac pumping chamber. Nevertheless, cardiac dysfunction (and ultimately heart failure) is a common complication in the SV population, and pharmacological heart failure therapies have largely been ineffective in mitigating the need for heart transplantation. Given that there are several inherent risk factors for ventricular dysfunction in the setting of SV in addition to probable differences in molecular adaptations to heart failure between children and adults, it is perhaps not surprising that extrapolated adult heart failure medications have had limited benefit in children with SV heart failure. Further investigations into the molecular mechanisms involved in pediatric SV heart failure may assist with risk stratification as well as development of targeted, efficacious therapies specific to this patient population. In this review, we present a brief overview of SV anatomy and physiology, with a focus on patients with a single morphological right ventricle requiring staged surgical palliation. Additionally, we discuss outcomes in the current era, risk factors associated with the progression to heart failure, present state of knowledge regarding molecular alterations in end-stage SV heart failure, and current therapeutic interventions. Potential avenues for improving SV outcomes, including identification of biomarkers of heart failure progression, implications of personalized medicine and stem cell-derived therapies, and applications of novel models of SV disease, are proposed as future directions.

Long Term Consequences of the Fontan Procedure and How to Manage Them

In 1971, Fontan and Baudet described a surgical technique for successful palliation of patients with tricuspid atresia. Subsequently, this technique has been applied to treat most forms of functional single ventricles and has become the current standard of care for long-term palliation of all patients with single ventricle congenital heart disease. Since 1971, the Fontan procedure has undergone several variations. These patients require lifelong management including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function along with multi organ evaluation. As these patients enter middle age, there is increasing awareness regarding the long-term complications and mortality. This review highlights the long-term outcomes of the Fontan procedure and management of late sequelae.