Numerical Study on the Impact of Central Venous Catheter Placement on Blood Flow in the Cavo-Atrial Junction

An in silico study is performed to investigate fluid dynamic effects of central venous catheter (CVC) placement within patient-specific cavo-atrial junctions. Prior studies show the CVC infusing a liquid, but this study focuses on the placement without any liquid emerging from the CVC. A 7 or 15-French double-lumen CVC is placed virtually in two patient-specific models; the CVC tip location is altered to understand its effect on the venous flow field. Results show that the CVC impact is trivial on flow in the superior vena cava when the catheter-to-vein ratio ranges from 0.15 to 0.33. Results further demonstrate that when the CVC tip is directly in the right atrium, flow vortices in the right atrium result in elevated wall shear stress near the tip hole. A recirculation region characterizes a spatially variable flow field inside the CVC side hole. Furthermore, flow stagnation is present near the internal side hole corners but an elevated wall shear stress near the curvature of the side hole's exit. These results suggest that optimal CVC tip location is within the superior vena cava, so as to lower the potential for platelet activation due to elevated shear stresses and that CVC geometry and location depth in the central vein significantly influences the local CVC fluid dynamics. A thrombosis model also shows thrombus formation at the side hole and tip hole. After modifying the catheter design, the hemodynamics change, which alter thrombus formation. Future studies are warranted to study CVC design and placement location in an effort to minimize CVC-induced thrombosis incidence.

New experimental animal model of intracardiac thrombus created with epicardial echocardiographic guidance

BACKGROUND

Models of intracardiac thrombus are very difficult to establish and have rarely been reported. We designed and established a new, inexpensive, practical animal model for intracardiac thrombus created with epicardial echocardiographic guidance.

METHODS

Male New Zealand white rabbits weighing 2 to 3.9 kg (3.10±0.58 kg) were used in this study. Cylindrical thrombi were created in plastic tubing and then aspirated with saline into a syringe. The thrombus in saline suspension was then slowly injected into a heart chamber and confirmed with echocardiography, including two-dimensional and contrast-enhanced ultrasound.

RESULTS

Intracardiac thrombi were created successfully in the left ventricle, right ventricle, and left and right atrial appendages. The average preparation time was about 3 hours. There were no significant differences among the four heart chambers in the success rate of thrombus model creation. Thrombi embolized to the pulmonary artery after failure of the right heart model. After failure of the left heart model, emboli were found in the carotid artery, renal artery, and truncus coeliacus. In two cases thrombi extended from the left ventricular apex into the aorta and in one case the thrombus extended from the left atrial appendage to the left atrium; there was no such extension from the other chambers. The rabbits' vital signs remained stable after establishment of the model, with no significant changes in heart structure or function.

CONCLUSIONS

This new method of creating an intracardiac thrombus model in rabbits showed initial success.