Incidence and Factors Associated with Thrombus Development
We report that in 290 patients with a CVC tip seated in the RA, incidental detection of RAT by clinically indicated TTE was 5.2%. To the best of our knowledge, this study is the largest series in which an incidence of catheter-associated RAT has been reported in patients with a catheter tip seated in the RA. Previous estimates of incidence range from 8.8-24% in cancer patients, 5.4% in hemodialysis patients, and nearly 30% as detected by autopsy in patients who died with a CVC present.3,9-12 However, these estimates were not specific for patients in whom the catheter tip is specifically present in the RA. Plodkowski et al noted that catheter-associated RAT is associated with the extent to which the catheter protrudes into the RA.12 Similarly, Gilon et al found a strong association between RAT and catheter tip placement in the RA as opposed to the cavoatrial junction or SVC.3 However, other studies have reported that catheter tip placement in the cavoatrial junction may not prevent RAT in comparison to placement in the RA.11,13 CVC catheters placed distally in the RA may encounter more “swirling” or turbulent blood flow and predispose to thrombus formation compared to catheters in the SVC in which the venous vessel wall may facilitate more laminar blood flow.
Our study confirms that the placement of a catheter tip in the RA entails a risk for RAT, raising concerns regarding institutional practices that may feature variations in recommended CVC insertion depth. Myriad complex factors may guide these practices such as balancing the potential for complications with achievement of the best possible infusion flow.14 Our study shows that the possibility of RAT when CVC protrudes beyond cavoatrial junction should be considered. Furthermore, our study demonstrates the ability of clinically indicated TTE to incidentally detect RAT.