Three-Dimensional High-Resolution Esophageal Manometry Study of the Esophagogastric Junction in Patients with Achalasia

BACKGROUND

A novel three-dimensional high-resolution esophageal manometry provides a dynamic 360° representation of the pressure at the esophagogastric junction.

AIMS

To describe the three-dimensional high-resolution esophageal manometry patterns of achalasia.

METHODS

We retrospectively included all consecutive patients who underwent three-dimensional high-resolution esophageal manometry before and after treatment (pneumatic dilatation or per-oral endoscopic myotomy) for achalasia between November 2016 and July 2017. The distribution of the pressures at the esophagogastric junction on three-dimensional high-resolution esophageal manometry was determined.

RESULTS

Eighteen patients were included. Mean integrated relaxation pressure was 20.7 mmHg, and median (range) Eckardt score was 7 (4-10). Nine patients were treated by pneumatic dilatation and seven by myotomy. Nine patients underwent three-dimensional high-resolution esophageal manometry after treatment. Before treatment, the esophagogastric junction pressure distribution was best observed at end expiration and during the 4 s of the integrated relaxation pressure measurement. During the integrated relaxation pressure, the lower esophageal sphincter was asymmetric in 12 patients with a high-pressure zone between the left and the posterior side of the esophagogastric junction. After treatment, five patients had a residual high-pressure point on the left or the posterior side of the esophagogastric junction.

CONCLUSIONS

Three-dimensional high-resolution esophageal manometry allows a simple assessment of the pressure topography at the EGJ. In patients with achalasia, we found the esophagogastric junction pressure to be asymmetric with a peak pressure on the greater curvature side. Three-dimensional high-resolution esophageal manometry has the potential to guide initial and redo treatments.

Assessment of boundary conditions for CFD simulation in human carotid artery

Computational fluid dynamics (CFD) is an increasingly used method for investigation of hemodynamic parameters and their alterations under pathological conditions, which are important indicators for diagnosis of cardiovascular disease. In hemodynamic simulation models, the employment of appropriate boundary conditions (BCs) determines the computational accuracy of the CFD simulation in comparison with pressure and velocity measurements. In this study, we have first assessed the influence of inlet boundary conditions on hemodynamic CFD simulations. We selected two typical patients suspected of carotid artery disease, with mild stenosis and severe stenosis. Both patients underwent digital subtraction angiography (DSA), magnetic resonance angiography, and the invasive pressure guide wire measured pressure profile. We have performed computational experiments to (1) study the hemodynamic simulation outcomes of distributions of wall shear stress, pressure, pressure gradient and (2) determine the differences in hemodynamic performances caused by inlet BCs derived from DSA and Womersley analytical solution. Our study has found that the difference is related to the severity of the stenosis; the greater the stenosis, the more the difference ensues. Further, in our study, the two typical subjects with invasively measured pressure profile and thirty subjects with ultrasound Doppler velocimeter (UDV) measurement served as the criteria to evaluate the hemodynamic outcomes of wall shear stress, pressure, pressure gradient and velocity due to different outlet BCs based on the Windkessel model, structured-tree model, and fully developed flow model. According to the pressure profiles, the fully developed model appeared to have more fluctuations compared with the other two models. The Windkessel model had more singularities before convergence. The three outlet BCs models also showed good correlation with the UDV measurement, while the Windkessel model appeared to be slightly better ([Formula: see text]). The structured-tree model was seen to have the best performance in terms of available computational cost and accuracy. The results of our numerical simulation and the good correlation with the computed pressure and velocity with their measurements have highlighted the effectiveness of CFD simulation in patient-specific human carotid artery with suspected stenosis.