Hypoplastic Left Heart Syndrome: A Review.

Hypoplastic left heart syndrome is a rare and poorly understood congenital disorder featuring a univentricular myocardium, invariably resulting in early childhood death if left untreated. The process to palliate this congenital cardiomyopathy is of high complexity and may include invasive interventions in the first week of life. The preferred treatment strategy involves a staged correction with 3 surgical procedures at different points in time. The Norwood procedure is usually performed within the first weeks of life and aims to increase systemic circulation and relieve pulmonary vascular pressure. This procedure is followed by the bidirectional Glenn and the Fontan procedures in later life, which offer to decrease stress in the ventricular chamber. The prognosis of children with this disease has greatly improved in the past decades; however, it is still largely driven by multiple modifiable and nonmodifiable variables. Novel and clever alternatives have been proposed to improve the survival and neurodevelopment of these patients, although they are not used as standard of care in all centers. The neurodevelopmental outcomes among these patients have received particular attention in the last decade in light to improve this very limiting associated comorbidity that compromises quality of life.

Biventricular repair as an alternative to single-ventricle palliation in a child with hypoplastic left heart structures: What the anesthesiologist should know.

Enhanced techniques for single-ventricle palliation (SVP), in which the Fontan procedure is the final phase, have improved the survival and quality of life in patients not eligible for biventricular repair (BiVR). However, Fontan physiology also is associated with predictable long-term consequences that ultimately affect quality of life and freedom from adverse events. Given this harsh reality, the advances in ventricular rehabilitation strategies and the conversion from SVP increasingly are being used to achieve biventricular circulation in patients with left-heart hypoplasia who previously were considered to be marginal or unacceptable candidates for BiVR. The techniques for ventricular recruitment include restriction of the atrial septal defect (ASD), atrioventricular valve repair, repair of left ventricular outflow obstruction, endocardial fibroelastosis resection, an augmented pulmonary blood flow, and catheter-based interventions. In addition, reverse double-switch surgery has been used as an option for patients with a left ventricle of insufficient size and function to support the systemic circulation, who would otherwise require a Fontan surgery. Despite improved management and surgical technique, the outcomes after biventricular staging repair and conversion remain variable, and the complications ultimately may exclude patients from future single-ventricle palliation or transplant. The anesthesiologist should have a basic understanding of the anatomy and physiology of this growing patient population in order to develop adequate perioperative management options.

Plastic Bronchitis and Protein-Losing Enteropathy in the Fontan Patient: Evolving Understanding and Emerging Therapies.

Plastic bronchitis (PB) and protein-losing enteropathy (PLE) are rare but potentially devastating complications of the Fontan circulation. PB occurs in ∼4% of Fontan patients, typically presents within 2 to 3 years of Fontan completion with chronic cough, wheezing, fever, or acute asphyxiation, and is characterised by proteinaceous airway casts that are expectorated or found on bronchoscopy. PLE develops in 4% to 13% of patients, usually within 5 to 10 years post Fontan, and manifests with edema, ascites, hypoalbuminemia, lymphopenia, hypogammaglobulinemia, and elevated fecal alpha-1 antitrypsin 1. These disorders have similar pathophysiology involving disruption of the lymphatic system resulting from elevated central venous pressure combined with elevated lymphatic production and inflammation, resulting in lymphatic drainage into low-pressure circuits such as the airways (PB) and duodenum (PLE). Our understanding of these disorders has greatly improved over the past decade as a result of advances in imaging of the lymphatic system through magnetic resonance lymphangiography and early success with lymphatic interventions including lymphatic embolisation, thoracic duct embolisation, and percutaneous thoracic duct decompression. Both PB and PLE require a multidisciplinary approach that addresses and optimises residual hemodynamic lesions through catheter-based intervention, lowers central venous pressure through medical therapy, minimises symptoms, and targets abnormal lymphatic perfusion when symptoms persist. This review summarises the pathophysiology of these disorders and the current evidence base regarding management, proposes treatment algorithms, and identifies future research opportunities. Key considerations regarding the development of a lymphatic intervention program are also highlighted.

Aerobic exercise and inspiratory muscle training increase functional capacity in patients with univentricular physiology after Fontan operation: A randomized controlled trial.

BACKGROUND: The effect of exercise training and its mechanisms on the functional capacity improvement in Fontan patients (FP) are virtually unknown. This trial evaluated four-month aerobic exercise training and inspiratory muscle training on functional capacity, pulmonary function, and autonomic control in patients after Fontan operation. METHODS: A randomized controlled clinical trial with 42 FP aged 12 to 30 years and, at least, five years of Fontan completion. Twenty-seven were referred to a four-months supervised and personalized aerobic exercise training (AET) or an inspiratory muscle training (IMT). A group of non-exercise (NET) was used as control. The effects of the exercise training in peak VO2; pulmonary volumes and capacities, maximal inspiratory pressure (MIP); muscle sympathetic nerve activity (MSNA); forearm blood flow (FBF); handgrip strength and cross-sectional area of the thigh were analyzed. RESULTS: The AET decreased MSNA (p = 0.042), increased FBF (p = 0.012) and handgrip strength (p = 0.017). No significant changes in autonomic control were found in IMT and NET groups. Both AET and IMT increased peak VO2, but the increase was higher in the AET group compared to IMT (23% vs. 9%). No difference was found in the NET group. IMT group showed a 58% increase in MIP (p = 0.008) in forced vital capacity (p = 0.011) and forced expiratory volume in the first second (p = 0.011). No difference in pulmonary function was found in the AET group. CONCLUSIONS: Both aerobic exercise and inspiratory muscle training improved functional capacity. The AET group developed autonomic control, and handgrip strength, and the IMT increased inspiratory muscle strength and spirometry. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02283255.

Impact of preoperative electrophysiological intervention on occurrence of peri/postoperative supraventricular tachycardia following Fontan surgery.

BACKGROUND: Little is known about the effects of preoperative electrophysiological study (EPS) and catheter ablation (CA) in Fontan surgery candidates with supraventricular tachycardia (SVT). OBJECTIVE: The purpose of this study was to investigate the clinical impact of EPS-guided intervention in Fontan surgery candidates with preceding SVT events. METHODS: A total of 109 consecutive patients with a history of SVT before Fontan surgery were divided into 3 groups: 44 in whom EPS with CA was attempted (CA group); 21 in whom EPS without CA was attempted (EPS group); and 44 in whom EPS was not performed (N group). The incidence and diagnosis of SVT, acute success rate of CA, and risk factors of peri/postoperative SVT were retrospectively investigated. RESULTS: The total incidence of SVT within 1 year after Fontan surgery was 34% (n = 37), with 91% of cases occurring within 1 month. Among the 71 SVT incidences diagnosed with EPS, 31 were atrioventricular reentrant tachycardias (AVRTs) involving twin atrioventricular nodes, 12 were atrioventricular nodal reentrant tachycardias, 12 were atrial tachycardias, 7 were orthodromic AVRTs via the accessory pathway, 7 were atrial flutters, and 2 were junctional tachycardias. The acute success rate of CA was 91% (48/53). The rate of peri/postoperative atrioventricular reciprocating SVT was significantly lower in the CA group than in the N or EPS group (11% vs 43% or 43%; P <.05). No/unsuccessful CA significantly increased the risk of peri/postoperative SVT in multivariate analysis (odds ratio 4.43; 95% confidence interval 1.69-11.59). CONCLUSION: Preoperative CA reduces peri/postoperative SVT occurrence in Fontan surgery candidates at high risk for SVT.

Cerebral arterial gas embolism in a patient with hypoplastic left heart syndrome treated with emergent hyperbaric oxygen: case report.

A 30-year-old female with a history of seizure disorder and hypoplastic left heart syndrome treated with a Norwood procedure in 1986 followed by a modified non-fenestrated Fontan (Left SVC to IVC to pulmonary arteries) with a known baffle leak presented to the emergency department. On day of presentation, the patient became unresponsive, with perioral cyanosis, rightward gaze and a left facial droop near the end of a platelet transfusion. An emergent non-contrast head CT revealed intracranial air in the right MCA distribution. She was taken to the hyperbaric chamber and was treated with a U.S. Navy Table 6 in a multiplace chamber with no extensions. Ten minutes into the treatment patient became more alert and spontaneously asked questions. The following day she was treated with a U.S. Navy Table 5. Patient had repeat CT of the head, which showed resolution of intracerebral gas and small areas of ischemia in right frontal lobe and right caudate. On hospital day five neurologic exam was normal, with 5/5 strength and no residual deficits. Treating the patient was a concern because patient has a single ventricle, in which the pulmonary artery is connected directly to the vena cava. There is very little data regarding the effects of hyperbaric oxygen (HBO2)therapy on single-ventricle physiology. Only two case reports of three pediatric patients treated with HBO2 for CAGE in a similar setting are known. In these cases the patients had improvements in their symptoms following HBO2. These cases and ours indicate HBO2 is feasible and indicated for CAGE in patients with cyanotic congenital heart disease.

Outcomes of Atrial Arrhythmia Surgery in Patients With Congenital Heart Disease: A Systematic Review.

Background The improved life expectancy of patients with congenital heart disease is often accompanied by the development of atrial tachyarrhythmias. Similarly, the number of patients requiring redo operations is expected to continue to rise as these patients are aging. Consequently, the role of arrhythmia surgery in the treatment of atrial arrhythmias is likely to become more important in this population. Although atrial arrhythmia surgery is a well-established part of Fontan conversion procedures, evidence-based recommendations for arrhythmia surgery for macroreentrant atrial tachycardia and atrial fibrillation in other patients with congenital heart disease are still lacking. Methods and Results Twenty-eight studies were included in this systematic review. The median reported arrhythmia recurrence was 13% (interquartile range, 4%-26%) during follow-up ranging from 3 months to 15.2 years. A large variation in surgical techniques was observed. Based on the acquired data, biatrial lesions are more effective in the treatment of atrial fibrillation than exclusive right-sided lesions. Right-sided lesions may be more appropriate in the treatment of macroreentrant atrial tachycardia; evidence for the superiority of additional left-sided lesions is lacking. There are not enough data to support the use of exclusive left-sided lesions. Theoretically, prophylactic atrial arrhythmia surgery may be beneficial in this population, but evidence is currently limited. Conclusions To be able to provide recommendations for arrhythmia surgery in patients with congenital heart disease, future studies should report outcomes according to the type of preoperative arrhythmia, underlying congenital heart disease, lesion set, and energy source. This is essential for determining which surgical techniques should ideally be applied under which circumstances.

Molecular Approaches in Single Ventricle Management.

Advances in medical and surgical management have significantly improved early outcomes in single ventricle congenital heart disease over the last 2 decades. Despite these advances, long-term outcomes remain suboptimal and therapeutic options to address systemic ventricular and/or Fontan failure are limited even in the modern era. Intricate molecular biologic techniques have shed light into the mechanisms of development of single ventricle disease. Efforts are underway to leverage this knowledge to improve clinical diagnosis, therapy, and prognostication. Cell-based therapies aimed at inducing cardiomyocyte proliferation and preventing delayed cardiac dysfunction have already entered the clinical realm. Several more novel biological therapies are expected to become available for patients with single ventricle disease in the near future. These scientific advancements provide us hope and reaffirm our faith that molecular medicine will usher in the next generation of therapies for single ventricle management.

Successful Ablation of Atrial Tachycardia Originating from Inside the Single Atrium and Conduit After a Fontan Operation.

An 18-year-old male who had a past medical history of an intracardiac total cavopulmonary connection (TCPC) operation was referred to our hospital for radiofrequency catheter ablation (RFCA) of supraventricular tachycardia (SVT). Two types of SVTs were induced, and 3-dimensional (3D) maps were created using an ultra-high-density 3-dimensional mapping system (Rhythmia). The earliest atrial activation site (EAAS) of SVT1 was at the superior part of the conduit, and the EAAS of SVT2 was at the inferior part of the single atrium (SA). The SVTs were terminated by energy deliveries to the EAAS from the conduit in SVT1 and from inside the single atrium in SVT2. Detailed maps of the SVTs were important to understand the mechanisms of the SVTs. The Rhythmia system was useful for the detailed mapping of complex arrhythmias. The use of Rhythmia in patients after a TCPC is difficult, because puncturing the TCPC conduit and proceeding and manipulating the Orion catheter via a narrow puncture hole are difficult. We were the first to succeed in ablating two atrial tachycardias (ATs) originating from the inside and outside of the conduit after a TCPC operation by using an ultra-high-density 3-dimensional mapping system.

Inspiratory muscle training did not improve exercise capacity and lung function in adult patients with Fontan circulation: A randomized controlled trial.

BACKGROUNDS: Patients with Fontan circulation have no subpulmonary ventricle and a passive pulmonary perfusion. Considerable percentage of the pulmonary blood flow is driven by pressure shift due to respiration. Impairments in respiratory musculature strength are associated with a reduced exercise capacity. This study investigated the effect of a daily six months inspiratory muscle training (IMT) on exercise and lung capacity in adult Fontan patients. METHODS: After a lung function and cardiopulmonary exercise test (CPET), 42 Fontan patients (50% female; 30.5 ± 8.1 years) were randomized into either an intervention group (IG), or a control group (CG). The IG performed a telephone-supervised, daily IMT of three sets with 10-30 repetitions for six months. RESULTS: After six months of IMT, the IG did not improve in any exercise and lung capacity parameter compared to CG. VO2peak (ΔVO2peak: IG: 0.05 [-1.53; 1.33] ml/kg/min vs. CG: -0.50 [-1.20; 0.78] ml/kg/min; p = .784) and FVC (ΔFVC: IG: 0.07 [-0.16; 0.22] l vs. CG:-0.05 [-0.24; 0.18] l; p = .377) remained unchanged, while FEV1 trended to improve (ΔFEV1: IG: 0.05 [-0.07; 0.13] l vs. CG: -0.10 [-0.19; 0.03] l; p = .082). Only oxygen saturation at rest improved significantly (ΔSpO2: IG: 1.50 [-0.25; 3.00] % vs. CG: -0.50 [-1.75; 0.75] %; p = .017). CONCLUSIONS: A daily six months IMT did not improve exercise and lung capacity and lung volumes in Fontan patients.

A Pilot Study of Inspiratory Muscle Training to Improve Exercise Capacity in Patients with Fontan Physiology.

While the Fontan procedure has improved life expectancy, patients with single ventricle physiology have impaired exercise capacity due to limited increase in pulmonary blood flow during activity. Enhancing the "thoracic pump" using inspiratory muscle training (IMT) may ameliorate this impairment. Adult nonsmokers with Fontan physiology were recruited through Boston Children's Hospital's outpatient clinic. Participants underwent cardiopulmonary exercise testing and pulmonary function testing, followed by 12 weeks of IMT and then repeat testing. The primary endpoint was change in % predicted peak oxygen consumption (VO2). Secondary endpoints were changes in other exercise metrics. Eleven patients (6 male) were enrolled. Median ages at time of enrollment and Fontan completion were 28.8 years (25.7, 45.5) and 7.8 years (3.9, 16.5), respectively. Average baseline maximal inspiratory pressure (MIP) was normal; only 2 patients had MIP <70% predicted. Peak work rate improved significantly from baseline after 12 weeks of IMT (116.5 ± 45.0 to 126.8 ± 47.0 W, P = 0.019). Peak VO2 tended to improve (baseline 68.1 ± 14.3, change + 5.3 ± 9.6% predicted, P = 0.12), as did VE/VCO2 slope (34.1 ± 6.7 to 31.4 ± 3.6, P = 0.12). There was no change in peak tidal volume or MIP. In a small cohort of Fontan patients with mostly normal MIP, IMT was associated with significant improvement in peak work rate and a trend toward higher peak VO2 and improved ventilatory efficiency. Larger studies are needed to determine if this reflects true lack of effect or whether this pilot study was underpowered for effect size, and whether IMT is more narrowly useful for patients with impaired MIP.

Successful Treatment of Protein-Losing Enteropathy and Plastic Bronchitis by Biphasic Cuirass Ventilation in a Patient with Failing Fontan Circulation.

We present a 16-year-old male patient with hypoplastic left heart syndrome who developed protein-losing enteropathy (PLE) and plastic bronchitis (PB) after a Fontan operation. He received medical therapies, including albumin infusion, unfractionated heparin, and high-dose anti-aldosterone therapy but could not obtain clinical relief. Biphasic cuirass ventilation (BCV) led to expectoration of bronchial casts and prompt resolution of PB. Notably, clinical symptoms related to PLE were dramatically improved after starting BCV. A brief period of BCV increased stroke volume from 26±1.4 to 39±4.0 mL. This case suggests that BCV could be an effective treatment for PLE in patients with failing Fontan circulation.

A stepwise approach to conduit puncture for electrophysiological procedures in patients with Fontan circulation.

Aims: In patients with Fontan circulation, the conduit may be punctured for electrophysiological procedures. We evaluated the feasibility and safety of a stepwise approach to conduit puncture in adults who have undergone Fontan operation. Methods and results: We included 13 consecutive patients with lateral tunnel or extracardiac conduit Fontan circulation [median age (interquartile range), 24.0 (16.0-25.0) years; seven men] who had undergone electrophysiological procedures. We performed a stepwise approach to conduit puncture: 1st, Brockenbrough needle; 2nd, Brockenbrough needle with snare; 3rd, extra-steep Brockenbrough needle with/without snare; 4th radiofrequency transseptal needle with/without snare; 5th, wiring through the puncture; 6th, conduit dilation with angioplasty balloon; 7th, non-compliant or cutting balloon; and 8th, Inoue dilator. In 12 patients, conduit puncture was successful. In two, one, and two patients with a lateral tunnel made of the pericardium or right atrial wall, conduit puncture was performed by steps 1st, 2nd, and 4th, respectively. In one, three, two, and one patient with the Goretex lateral tunnel or extracardiac conduit, conduit puncture was performed by steps 1st, 6th, 7th, and 8th, respectively. Puncture time was significantly longer in patients with Goretex conduits than with pericardial conduits [62.0 (50.0-120.0) and 11.5 (10.0-14.8) min, respectively; P < 0.001]. A snare was necessary in patients with angles ≤ 35° between the conduit wall and vertical line. Conclusion: A stepwise conduit puncture approach is feasible and safe in patients with lateral tunnel and extracardiac conduit Fontan circulation. Goretex conduit puncture was more difficult than pericardial conduit puncture.