Introduction
Introduction
Ten to 20 % of hemodialysis patients are dependent on external catheters as a permanent
access [1 2 3
Materials and Methods
Materials and Methods
Hemodialysis access device
The system (DialockTM , Biolink Corp., Middleboro, MA, USA) consists of two 11 F silicone catheters connected
to a titanium port with the dimensions 5 × 2.5 × 1.25 cm. The port has a double needle
passage to be punctured percutaneously by two specially designed needle-cannulas.
A valve assembly within the port prevents leakage and automatically closes when the
needles are withdrawn. After the dialysis session an antithrombotic lock with heparin
is instilled to prevent clotting of the catheters. The CE-marked and FDA-approved
system is available as a set (A. Schulz-Lauterbach, Iserlohn, Germany).
Implantation procedure
All devices were implanted in an angiographic suite by an interventional radiologist,
in cooperation with a surgeon (who prepared the port pocket). First, the jugular vein
was localized using ultrasound. Preferrably the right side was chosen for access.
In two cases with occlusion or high-grade stenosis of the right brachiocephalic vein
the left jugular vein was accessed. After local anesthesia (Meaverin, Mepivacainhydrochlorid
1 %, Rhone-Poulenc-Rorer GmbH, Köln, Germany) and double puncture of the vein the
two catheters were inserted through a peel-away sheath. The catheter tips were placed
at different levels in the right atrium under fluoroscopic control. For implantation
of the port local anesthetics (Meaverin) were distributed spaciously into the subcutaneous
tissue of the anterior chest wall a few centimeters below the clavicle. After a transverse
incision of 6 cm length a pocket was prepared. The catheters were tunneled from the
venous accesss site to the port pocket and connected to the port. After fixation of
the port to the pectoral fascia the pocket was closed by suture.
Patients
The Dialock port system was implanted in 4 female and one male patients (average age
of 59 years). All of our patients had external central venous catheters with infectious
complications and inadequate veins to create a new native or prosthetic fistula after
a history of failed fistulas and/or grafts. Dialock implantation was considered as
an ultimate option of treatment.
The indication was hemodialysis access in 4 patients with chronic renal failure and
plasmapheresis in one patient with myasthenia. All implants were performed under local
anesthesia. All patients received prophylactic systemic antibiotics (2 g Spizef i.
v., Cefotiam, Takeda, Aachen, Germany) two hours before implantation.
Results
Results
In all 5 patients the implantation of the catheters and the port was technically successful.
Healing of the implant was uneventful. There was no implant or puncture site infection.
The total average duration of dialysis with the port system was 3.6 months at the
time of report writing.
One patient has been undergoing weekly plasmapheresis for now more than half a year
without complication. The four hemodialysis patients underwent dialysis three times
a week.
One of the dialysis patients developed a hematoma at the port site 14 days after implantation,
which required surgical revision. After this reintervention the system has been working
now for more than half a year without complications.
Another dialysis patient developed a moderate hematoma 10 days after implantation,
without the need for treatment. After three months she was readmitted with signs of
septicsemia, which gave reason to explant the port. However, a port infection was
not confirmed.
The third dialysis patient showed a thrombotic occlusion of both catheter tips 8 days
after implantation. Catheter cleaning via access port using different guide wires
and a stripping maneuver of the fibrin sheaths covering both outer catheter tips by
a transfemoral snare did not prevent reocclusion. The port pocket was reopened to
exchange the catheters. This revealed a tear in one of the catheters close to the
port connector. After catheter exchange and a coumarin therapy the system is working
well up to date.
The fourth dialysis patient showed migration of the catheter tips from the right atrium
to the orifice of the inferior vena cava within one week after implantation, due to
cranial migration of the port within the pocket. Obviously, this was provoked by needle
puncturing the port from below for dialysis access without fixing it by palpation.
Surgical revision of the port pocket with thorough refixation of the port more caudally
solved this problem.
Discussion
Discussion
The Dialock system represents a new approach in vascular access for hemodialysis and
plasmapheresis in patients who have no viable vascular site for creation of a fistula.
It is a modification of the vascular access port used for chemotherapy [4
Due to the novelty of the system there are only limited data available in the literature
[5 6 7
Hematoma surrounding the Dialock device was observed in 7.2 % of the cases [7 7
The study reports 11 infections in 23 patients [5 6 7 8 8 9 8
Two devices were explanted because of thrombotic material around catheter tips, in
order to rule out infection [6 10
Conclusion
Conclusion
The Dialock system offers a new concept and an interesting alternative to external
catheters in the vascular access strategy for hemodialysis and plasmapheresis. With
regard to the number of problems and complications encoutered in our small group of
patients as well as in the US/French pilot study, it requires further studies to determine
the place of this device in the field of vascular access.
Fig. 1 Chest X-ray after implantation of the hemodialysis access device: * subcutaneous port
below the left clavicle, punctured from below by two hemodialysis cannulas. → Tips
of the catheters at different levels in the right atrium (Shaldon catheter in the
right subclavian vein).
Fig. 2 Dialock port system in use for hemodialysis (1 week after implantation): Port system
punctured by twin needle-cannulas. → Suture of the port pocket.
