Blood flow in the foreign-body capsules surrounding surgically implanted subcutaneous devices.
BACKGROUND
Surgically implanted devices initiate inflammatory mechanisms and wound healing events and result in the formation of a thick fibrotic capsule that surrounds the device. To investigate the foreign-body response to devices of clinically relevant size, we used microspheres to determine regional blood flow patterns in the foreign-body capsule (FBC) and surrounding subcutaneous tissue after device implantation.


METHODS
In 10 canines, we implanted 40 subcutaneous devices (polysulfone n = 20, silicone-coated n = 10, titanium n = 10). Via thoracotomy, animals were instrumented with left atrial and aortic vascular access catheters for serial microsphere injections and reference blood sampling. Regional blood flow was repeatedly determined in the FBC, subcutaneous fascia surrounding the FBC, and subcutaneous fascia distal to the surgical site up to 19 wk after device implantation (n = 55 determinations).


RESULTS
Compared with normal blood flow in subcutaneous fascia distal to the surgical site, blood flow increased in FBCs surrounding each device material (polysulfone P = 0.0035, silicone-coated P < 0.0001, titanium P < 0.0001). Additionally, blood flow increased in the subcutaneous fascia within half a centimeter of fibrous capsules encasing polysulfone (P = 0.0081) but not silicone (P = 0.3706) or titanium (P = 0.8160) devices. The time-course of measured blood flow changes within FBCs were similar for polysulfone and silicone but not for titanium.


CONCLUSIONS
Surgically implanted subcutaneous devices of clinically relevant size elicit increases in blood flow in the FBC as well as surrounding fascia. Device material may influence regional blood flow patterns.
Bartoli
Carlo R
CR
Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA. crbart02@louisville.edu
Godleski
John J
JJ
D000818:Animals; D004285:Dogs; D005260:Female; D005547:Foreign Bodies / Q000503:physiopathology*; D008863:Microspheres; D019736:Prostheses and Implants; D012039:Regional Blood Flow; D040521:Subcutaneous Tissue / Q000098:blood supply*