Inclusion Criteria:  Adults (18 years of age or older). In need of a tCDC with an expected treatment time of at least 7 days.  Exclusion Criteria:  Unable to give written informed consent. Intravenous pacemaker or a PICC-line via right-sided central veins in situ. Known right-sided CVS. AV fistula on the upper extremity. Findings associated with CVS or thrombosis during the pre-procedural US exam. History of central venous vascular interventions including stents, dilatations and more (but not previous central venous catheterization). Central venous catheter in the right internal jugular vein or in the right subclavian vein in situ. Either the right jugular vein or the right subclavian vein unavailable for catheterization due to, e.g., local skin infection, thrombosis or inability to visualize the vein with ultrasound. Known allergy to iodinated contrast agents. BMI >35 kg/m2.