Patient-Specific CT-Based Fluid-Structure-Interaction Aorta Model to Quantify Mechanical Conditions for the Investigation of Ascending Aortic Dilation in TOF Patients

Background

Some adult patients with Tetralogy of Fallot (TOF) were found to simultaneously develop ascending aortic dilation. Severe aortic dilation would lead to several aortic diseases, including aortic aneurysm and dissection, which seriously affect patients' living quality and even cause patients' death. Current practice guidelines of aortic-dilation-related diseases mainly focus on aortic diameter, which has been found not always a good indicator. Therefore, it may be clinically useful to identify some other factors that can potentially better predict aortic response to dilation.

Methods

20 TOF patients scheduled for TOF repair surgery were recruited in this study and were divided into dilated and nondilated groups according to the Z scores of ascending aorta diameters. Patient-specific aortic CT images, pressure, and flow rates were used in the construction of computational biomechanical models.

Results

Simulation results demonstrated a good coincidence between numerical mean flow rate at inlet and the one obtained from color Doppler ultrasonography, which implied that computational models were able to simulate the movement of the aorta and blood inside accurately. Our results indicated that aortic stress can effectively differentiate patients of the dilated group from the ones of the nondilated group. Mean ascending aortic stress-P1 (maximal principal stress) from the dilated group was 54% higher than that from the nondilated group (97.97 kPa vs. 63.47 kPa, p value = 0.044) under systolic pressure. Velocity magnitude in the aorta and aortic wall displacement of the dilated group were also greater than those of the nondilated group with p value < 0.1.

Conclusion

Computational modeling and ascending aortic biomechanical factors may be used as a potential tool to identify and analyze aortic response to dilation. Large-scale clinical studies are needed to validate these preliminary findings.

Late management of the aortic root after repair of tetralogy of Fallot: A European multicentre study

OBJECTIVES

We sought to determine the indications, type, and outcomes of reoperations on the aortic root after repair of tetralogy of Fallot (TOF).

METHODS

Eleven centers belonging to the European Congenital Heart Surgeons Association contributed to the data collection process. We included 36 patients who underwent surgical procedures on the aortic root, including surgery on the aortic valve and ascending aorta, between January 1975 and December 2017. Original diagnoses included TOF-pulmonary stenosis (n = 18) and TOF-pulmonary atresia (n = 18). The main indications for reoperation were aortic insufficiency (n = 19, 53%), aortic insufficiency and dilatation of the ascending aorta (n = 10, 28%), aortic root dilatation (n = 4, 11%), and ascending aorta dilatation (n = 3, 8%).

RESULTS

The median age at reoperation was 30.4 years (interquartile range 20.3-45.3 years), and mechanical aortic valve replacement was the most common procedure performed. Five patients died early after reoperation (14%), and larger ascending aorta diameters were associated with early mortality (P = .04). The median age at the last follow-up was 41.4 years (interquartile range 24.5-51.6 years). Late death occurred in five patients (5/31, 16%). Most survivors (15/26, 58%) were asymptomatic at the last clinical examination (New York Heart Association, NYHA class I). The remaining patients were NYHA class II (n = 7) and III (n = 3). The most common symptoms were fatigue (n = 5), dyspnea (n = 4), and exercise intolerance (n = 3).

CONCLUSIONS

Reoperations on the aortic root are infrequent but may become necessary late after TOF repair. The main indications for reoperation are aortic insufficiency, either isolated or associated with a dilatation of the ascending aorta. The surgical risk at reoperation was high and the presence of ascending aorta dilation is related to higher mortality.

Ascending aortic dilation in adult patients with congenital ventricular septal defect: An observational study

Many adult patients with congenital ventricular septal defect (VSD) also developed ascending aortic dilation, but few report the clinical features and surgical management of these patients. This study was designed to study ascending aortic dilation in adult patients with congenital VSD, and summarized the treatment experience and prognosis.To assess the clinical features and surgical management, we performed a retrospective analysis on preoperative data, intraoperative data, and postoperative data from the adult patients with congenital VSD who developed ascending aortic dilation in our institution from February 2010 to December 2016.From February 2010 to December 2016, we operated on 13 adult patients (12 males, 92.31%) with VSD who developed ascending aortic dilation. Median age was 37 (interquartile range 14) years. All patients suffered from perimembranous VSD and received surgical treatment. Their symptoms were all improved after surgery, no deaths occurred.Surgery is feasible for the ascending aortic dilation in adult patients with congenital VSD. Both proper perioperative treatment and close monitoring are required for the successful surgery.

Marfan's syndrome: an overview

Marfan's syndrome is an autosomal dominant condition with an estimated prevalence of one in 10,000 to 20,000 individuals. This rare hereditary connective tissue disorder affects many parts of the body. The diagnosis of Marfan's syndrome is established in accordance with a review of the diagnostic criteria, known as the Ghent nosology, through a comprehensive assessment largely based on a combination of major and minor clinical manifestations in various organ systems and the family history. Aortic root dilation and mitral valve prolapse are the main presentations among the cardiovascular malformations of Marfan's syndrome. The pathogenesis of Marfan's syndrome has not been fully elucidated. However, fibrillin-1 gene mutations are believed to exert a dominant negative effect. Therefore, Marfan's syndrome is termed a fibrillinopathy, along with other connective tissue disorders with subtle differences in clinical manifestations. The treatment may include prophylactic β-blockers and angiotensin II-receptor blockers in order to slow down the dilation of the ascending aorta, and prophylactic aortic surgery. Importantly, β-blocker therapy may reduce TGF-β activation, which has been recognized as a contributory factor in Marfan's syndrome. The present article aims to provide an overview of this rare hereditary disorder.