Maldistribution of pulmonary blood flow in patients after the Fontan operation is associated with worse exercise capacity

Background

Maldistribution of pulmonary artery blood flow (MPBF) is a potential complication in patients who have undergone single ventricle palliation culminating in the Fontan procedure. Cardiovascular magnetic resonance (CMR) is the best modality that can evaluate MPBF in this population. The purpose of this study is to identify the prevalence and associations of MPBF and to determine the impact of MPBF on exercise capacity after the Fontan operation.

Methods

This retrospective single-center study included all patients after Fontan operation who had maximal cardiopulmonary exercise test (CPET) and CMR with flow measurements of the branch pulmonary arteries. MPBF was defined as >?20% difference in branch pulmonary artery flow. Exercise capacity was measured as percent of predicted oxygen consumption at peak exercise (% predicted VO₂). Linear and logistic regression models were used to determine univariate and multivariable predictors of exercise capacity and correlates of MPBF, respectively.

Results

A total of 147 patients who had CMR between 1999 and 2017 were included (median age at CMR 21.8?years [interquartile range (IQR) 16.5–30.6]) and the median time between CMR and CPET was 2.8?months [IQR 0–13.8]. Fifty-three patients (36%) had MPBF (95% CI 29–45%). The mean % predicted VO₂ was 63?±?16%. Patients with MPBF had lower mean % predicted VO₂ compared to patients without MPBF (60?±?14% versus 65?±?16%, p?=?0.04). On multivariable analysis, a lower % predicted VO₂ was independently associated with longer time since Fontan, higher ventricular mass-to-volume ratio, and MPBF. On multivariable analysis, only compression of the branch pulmonary arteries by the ascending aorta or aortic root was associated with MPBF (OR 6.5, 95% CI 5.6–7.4, p?<?0.001).

Conclusion

In patients after the Fontan operation, MPBF is common and is independently associated with lower exercise capacity. MPBF was most likely to be caused by pulmonary artery compression by the aortic root or the ascending aorta. This study identifies MPBF as an important risk factor and as a potential target for therapeutic interventions in this fragile patient population.

     

Atrial function in the Fontan circulation: comparison with invasively assessed systemic ventricular filling pressure

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Application of machine learning in screening for congenital heart diseases using fetal echocardiography

The International Journal of Cardiovascular Imaging - There is a growing body of literature supporting the utilization of machine learning (ML) to improve diagnosis and prognosis tools of...     

High prevalence of vitamin D deficiency in type 1 diabetes mellitus and healthy children

Epidemiological studies suggest a link between vitamin D deficiency in early life and the later onset of type 1 diabetes. The aim of this matched case-control study was to find the association between vitamin D and T1DM then to study the difference in the level of vitamin D in T1DM and healthy subjects, and to determine the associated environmental risk factors in young Qatari population. The study was carried out among T1DM children and healthy subjects below 16 years at the pediatric endocrinology outpatient clinics of the Hamad General Hospital and the Primary Health care Clinics (PHCs). The survey was conducted over a period from 6 August to 25 December 2007. The subjects were Qatari nationals male and female aged below 16 years. The study is based on matching by age, gender and ethnicity of 170 cases with those of 170 controls. Face-to-face interviews were based on a questionnaire that included variables such as socio-demographic information, assessment of non-dietary covariates, assessment of dietary intake, vitamin D intake, type of feeding, clinical manifestations and laboratory investigations. Their health status was assessed by medical conditions, family history, BMI, past or present clinical manifestations, 25 (OH)D, Calcium, alkaline phosphatase, phosphorus, HbA1C, PTH, Mg and creatinine analysis. The study revealed that vitamin D deficiency was considerably higher in T1DM children (90.6%) compared to non-diabetic children (85.3%). There was a significant difference found in the mean value of vitamin D between T1DM and non-diabetic children (P = 0.009). There were statistically significant differences between type 1 diabetic and healthy subjects with respect to the occupation of parents (P < 0.001) and consanguinity rate (P < 0.047). Family history of vitamin D deficiency was considerably higher among T1DM children (35.3%) with a significant difference between diabetic and non-diabetic children (22.9) (P < 0.012). Vitamin D supplement with breast milk was very poor in diabetic children (37.4%) compared to non-diabetic children (47.7%). Majority of the studied subjects were breast-fed children (95.1% of diabetic children and 97.2% of healthy children). Multivariate logistic regression analysis revealed that fathers and mothers occupation, family history of DM, physical activity, low duration of time under sun light, breast feeding less than 6 months and low vitamin D level were considered as the main factors associated with the T1DM. In conclusion, the present study revealed that vitamin D deficiency was higher in T1DM children compared to non-diabetic. Moreover, vitamin D deficiency was common in Qatari young population. Vitamin D intake was very poor in children and it shows that supplementing infants with vitamin D might be a safe and effective strategy for reducing the risk of T1DM.     

Short‐term results in infants with multiple left heart obstructive lesions

Objective: Deciding on a surgical pathway for neonates with ≥2 left heart obstructive lesions is complex. Predictors of the successful biventricular (2V) repair in these patients are poorly defined. The goal of our study was to identify patients who underwent the 2V repair and assess anatomic and echocardiographic predictors of success.
Design: Infants born between July 2015 and August 2017 with ≥2 left heart obstructive lesions with no prior interventions were identified (n = 19). Patients with aortic or mitral valve (MV) atresia and critical aortic stenosis were excluded. Initial echocardiograms were reviewed for aortic, MV, tricuspid valve annulus size, and left (LV) and right (RV) ventricle diastolic longitudinal dimensions. The valve morphology and presence of a ventricular septal defect (VSD) and coarctation were assessed. Clinical outcomes included successful 2V repair, complications, and repeat interventions or surgeries. Failed 2V repair was defined as a takedown to single ventricle (1V) physiology, cardiac transplantation, or death.
Results: For 2V repair, 14/19 patients were selected and for 1V, 5/19 patients were selected. Initial surgical procedures of the 2V group were simple coarctation repair (5), complex coarctation/arch reconstruction +/− septal defect closure (6), hybrid stage 1 (2), and none (1). Three of the 2V patients required reintervention in the first 90 days. The LV to RV diastolic longitudinal ratio >0.75 and mitral/tricuspid ratio of <0.8 were observed in 13/14 of the 2V patients. The LV:RV ratio and the aortic valve z score were significantly larger in the 2V group compared to the 1V group. All patients in the 1V group had a nonapex forming LV. There was no mortality with follow‐up to three years of age.
Conclusions: This study showed excellent short‐term and midterm surgical results in the 2V population. The LV:RV diastolic longitudinal ratio may be a useful tool in the risk stratification of a successful 2V repair even in cases with a small MV.