Fibrin sheath develops around the catheter.
The sheath acts like a one-way valve and prevents adequate and free pulling of blood through the catheter.
The fibrin sheath can be disrupted either with an angioplasty or can be stripped using a snare device. Post-angioplasty shows the contrast flowing freely in to right atrium.
The fibrin sheath can extend from the cuff to beyond the catheter tip