Classic-Pattern Dyssynchrony Is Associated with Outcome in Patients with Fontan Circulation.

BACKGROUND: Morbidity and mortality increase as Fontan patients age into adulthood. Limited studies have examined cardiac magnetic resonance and echocardiographic parameters to predict death and transplantation in children after the Fontan operation. The aim of this study was to investigate echocardiographic parameters in adolescents and adults after Fontan operation, including myocardial mechanics such as classic-pattern dyssynchrony (CPD), as predictors of transplantation or death. METHODS: In a cross-sectional retrospective study, strain analysis was performed on echocardiographic studies performed between 2001 and 2015 on 110 patients with single-ventricle physiology after the Fontan procedure. Strain curves were measured and visually assessed for the presence of CPD. The primary end point was death or transplantation after a follow-up period of 85 ± 35 months after echocardiography. RESULTS: The median age at the date of echocardiography was 20 years (range, 3-45 years). Of 110 patients, 28 had undergone transplantation. During the study period, three patients died after transplantation and seven patients died without undergoing transplantation. CPD was seen in 16 and protein-losing enteropathy in 21 of 110 patients. On multivariate analysis, CPD (hazard ratio [HR], 9.4; 95% confidence interval [CI], 2.6-34.6), protein-losing enteropathy (HR, 10.6; 95% CI, 3.4-33.2), systolic blood pressure (HR, 0.954; 95% CI, 0.913-0.996), systolic/diastolic duration ratio (HR, 6.83; 95% CI, 1.33-35.0), and E-wave deceleration time (HR, 0.98; 95% CI, 0.97-0.99) were independently associated with the primary end point. CONCLUSIONS: CPD, protein-losing enteropathy, and systolic and diastolic ventricular dysfunction are significantly associated with transplantation or death in Fontan-operated patients. In selected patients, the presence of CPD may be a basis to investigate cardiac resynchronization therapy as a treatment strategy.

Asymmetric Regional Work Contributes to Right Ventricular Fibrosis, Inefficiency, and Dysfunction in Pulmonary Hypertension versus Regurgitation.

BACKGROUND: Right ventricular (RV) pressure loading from pulmonary hypertension (PH) and volume loading from pulmonary regurgitation (PR) lead to RV dysfunction, a critical determinant of clinical outcomes, but their impact on regional RV mechanics and fibrosis is poorly characterized. The aim of this study was to test the hypothesis that regional myocardial mechanics and efficiency in RV pressure and volume loading are associated with RV fibrosis and dysfunction. METHODS: Eight PH, six PR, and five sham-control rats were studied. The PH rat model was induced using Sugen5416, a vascular endothelial growth factor receptor 2 inhibitor, combined with chronic hypoxia. PR rats were established by surgical laceration of the pulmonary valve leaflets. Six (n = 4) or 9 (n = 4) weeks after Sugen5416 and hypoxia and 12 weeks after PR surgery, myocardial strain and RV pressure were measured and RV pressure-strain loops generated. We further studied RV regional mechanics in 11 patients with PH. Regional myocardial work was calculated as the pressure-strain loop area (mm Hg ∙ %). Regional myocardial work efficiency was quantified through wasted work (ratio of systolic lengthening to shortening work). The relation of regional myocardial work to RV fibrosis and dysfunction was analyzed. RESULTS: In rats, PH and PR induced similar RV dilatation, but fractional area change (%) was lower in PH than in PR. RV lateral wall work was asymmetrically higher in PH compared with sham, while septal work was similar to sham. In PR, lateral and septal work were symmetrically higher versus sham. Myocardial wasted work ratio was asymmetrically increased in the PH septum versus sham. Fibrosis in the RV lateral wall, but not septum, was higher in PH than PR. RV fibrosis burden was linearly related to regional work and to measures of RV systolic and diastolic function but not to wasted myocardial work ratio. Patients with PH demonstrated similar asymmetric and inefficient regional myocardial mechanics. CONCLUSIONS: Asymmetric RV work and increased wasted septal work in experimental PH are associated with RV fibrosis and dysfunction. Future investigation should examine whether assessment of asymmetric regional RV work and efficiency can predict clinical RV failure and influence patient management.

Progressive loss of bone mass in children with Fontan circulation.

OBJECTIVE: We investigated bone mineral density (BMD) at different ages after the Fontan completion, and we evaluated the relationship between BMD, vitamin D levels, and pertinent patient variables. METHODS: A cross-sectional sample of 64 patients was examined with dual-energy X-ray absorptiometry (DXA) scans to determine BMD. Of these patients, 24 were also examined with BoneXpert software to determine bone mass density (BMX), expressed as the bone health index (BHI). Blood samples from all patients were analyzed. Patients were divided into three different age groups; A: 4-9 years old (n = 22), B: 10-15 years old (n = 21), and C: 16-18 years old (n = 21). RESULTS: Overall, BMD z scores were (mean ± SD): -1.0 ± 1.3 for the lumbar spine and -0.2 ± 1.2 for the total body. Groups B and C had significantly lower z score values compared to group A. Of patients in group C, 35% had z score values ≤-2 SD of the mean of the healthy population. There was no difference related to systemic ventricular anatomy (left or right); however, patients with lateral tunnels had lower BMD than patients with extra cardiac conduits. Overall, the BHI z score was (mean ± SD): -1.2 ± 0.9, but low BMX did not correlate with low BMD. The 25-hydroxy vitamin D level was 58 ± 30 nmol/L. Vitamin D levels decreased with age: in group C, 33.3% of patients exhibited vitamin D deficiencies. Vitamin D levels were not correlated with bone mineral densities. CONCLUSION: BMD levels decreased with age in patients with Fontan circulation. Different bone components were involved. Vitamin D levels also decreased with age, but they were not consistently associated with bone mineral densities. The single factor most predictive of low BMD was a lateral tunnel Fontan, compared to an extra cardiac Fontan.