Computational Fluid Dynamic Assessment of Patients with Congenital Heart Disease from 3D Rotational Angiography

For congenital heart disease patients, multiple imaging modalities are needed to discern anatomy and functional information such as differential blood flow. During cardiac catheterization, 3D rotational angiography (3DRA) can provide CTA-like images, enabling anatomical information and intraprocedural guidance. We seek to establish whether unique aspects of this technique can also generate quantitative functional blood flow information. We propose that systematic integration of 3DRA imaging, catheter hemodynamic information, and computational fluid dynamics (CFD), can provide quantitative information regarding blood flow dynamics and energetics, without additional imaging or procedures. We report a single center retrospective feasibility study comprising four patients with 3DRA imaging and a complete set of hemodynamic data. 3DRA was processed and segmented to reconstruct vascular regions of interest (ROI), and a computational grid for CFD modeling of blood flow through the ROI was generated. Blood flow was simulated by integrating catheter hemodynamic data to devise boundary conditions at vascular ROI inlets and outlets. The 3DRA-based workflow successfully generated key computational outputs commonly used for cardiovascular applications, including flow patterns, distribution fractions, wall shear stress. Computational outputs obtained were as detailed and resolved as those obtained from more commonly used CT or MR angiography. Accuracy was confirmed by comparing computed flow distributions with measurements for 2 cases, showing less than 2.0% error from the measured data. Systematic integration of catheter hemodynamic information, 3DRA imaging, and CFD modeling, provides an effective and feasible alternative to obtain important quantitative blood flow information and visualization, without additional imaging.

Healing of rotator cuff tendons using botulinum toxin A and immobilization in a rat model

Background

We evaluated effects of botulinum toxin A (Botox) and cast immobilization on tendon healing in a rat model. Injection of Botox into rat supraspinatus was hypothesized to reduce muscle active force and improved healing.

Methods

Eighty-four supraspinatus tendons were surgically transected and repaired in 42 Sprague-Dawley rats (transosseous technique). After repair, supraspinatus muscle was injected with saline or Botox (3 or 6 U/kg). Half the shoulders were cast-immobilized for the entire postoperative period; half were allowed free cage activity. Histology was examined at 2, 4, 8, and 12 weeks. A healing zone cross-sectional area was measured, and biomechanical testing of repair strength and tendon viscoelastic properties was conducted at 4 and 12 weeks.

Results

Botox alone and cast immobilization alone exhibited increased ultimate load compared with controls (saline injection, no immobilization) at 4 weeks. No difference in ultimate load occurred between Botox-only and cast-only groups. At 12 weeks, the Botox (6 U/kg) plus cast immobilization group was significantly weakest (p < 0.05). A trend was shown toward decreased healing zone cross-sectional areas in casted groups.

Conclusions

Supraspinatus Botox injection after rotator cuff repair might help protect the repair. However, cast immobilization plus Botox administration is harmful to rotator cuff healing in a rat tendon model.