While the debate over catheter tip shape and its resulting impact on patency has been settled, it is also important to understand that much has to do with catheter tip location. 

When dealing with vascular catheterization in mice and rats, the catheter tip must be positioned in the ideal location for what is considered "optimal patency." When the tip sits in the ideal location and with proper maintenance, patency can be extended for months. 

Within the scope of the procedure itself, one must consider that catheter insertion length may either be too short, too long, or ideal. Let's explore all three.

Carotid Artery

• Too Short - When the catheter insertion length is too short, the catheter tip sits in the artery. Clot formation occurs quite quickly, and patency is lost. 
• Too Long - When the catheter insertion length is considered too long, the catheter tip sits near, or in the left ventricle; partially occluding blood flow. The animal usually dies within a few days post-surgery. 
• Ideal - When the catheter insertion length is considered ideal, the catheter tip sits at the entrance of the aortic arch. There will be no clot formation, with observed high blood pressure from the left ventricle. In this situation, patency is "optimal". 

Jugular Vein 

• Too Short - When the catheter insertion length is too short, the catheter tip sits in the subclavian or superior vena cava. In this instance, a clot/biofilm formation occurs quickly. Patency is generally lost, withdrawing first. 
• Too Long - When the catheter insertion length is too long, the catheter tip sits deep in the atrium. In some instances, it may be against the valve wall or entering the inferior vena cava. Clot/biofilm formation generally occurs, and patency is lost. 
• Ideal - When the catheter insertion length is considered ideal, the catheter tip sits at the entrance of the right atrium. Patency is "optimal" as it takes much longer for a clot/biofilm to occur. 

Technique Matters: How do I achieve optimal placement and patency? 

These topics and more, are covered in-depth in our live virtual surgical training courses. Registration is now open. Learn more, https://www.instechlabs.com/education/virtual-training