Blood vessels reorganize after face transplantation surgery
CHICAGO, USA: For the first time, researchers have found that the blood vessels in face transplant recipients reorganize themselves. This finding has led to an understanding of the biological changes that occur after full-face transplantation. The findings could help improve surgical planning and assessment of potential complications in face transplant patients.
Face transplantation is a recent development in reconstructive surgery for patients who have lost some or all of their face through injury or disease. The first full-face transplantation in the U.S. was carried out at Brigham and Women's Hospital in Boston in 2011. Hospital specialists have subsequently performed full-face transplantations on three additional patients.
As part of the procedure, surgeons connect the patient's major arteries and veins to those from a donor face, or facial allograft, to ensure healthy circulation in the transplanted tissue. Because the technology is new, not much is known about the vascular changes that help blood penetrate, or perfuse, into the transplanted tissue. The development of new blood vessel networks in transplanted tissue is critical to the success of face transplant surgery.
"All three patients included in this study at Brigham and Women's maintain excellent perfusion, or blood flow, the key element of viability of the facial tissues and the restoration of form and function to those individuals who otherwise had no face," said study co-author Dr. Frank J. Rybicki, director of the hospital's Applied Imaging Science Laboratory. "We assumed that the arterial blood supply and venous blood return were simply from the connections of the arteries and the veins at the time of the surgery."
In order to learn more, Rybicki and Dr. Kanako K. Kumamaru, research fellow at the Applied Imaging Science Laboratory, used 320-detector row dynamic computed tomography angiography (CTA) to study the facial allografts of the three patients one year after successful transplantation. The CTA technology offers imaging over 16 cm of coverage, enabling the researchers to view collateralization, a process in which the body stimulates existing blood vessels to elongate, widen and form new connections. Collateralization often results from anastomoses, or branches formed between adjacent blood vessels.
"The key finding of this study is that after full-face transplantation there is a consistent, extensive vascular reorganization that works in concert with the larger vessels that are connected at the time of surgery," Kumamaru said.
The results showed that the new blood vessel networks course posteriorly, or toward the ears and even farther behind the head, in addition to the large arteries and veins that course anteriorly in the face, or close to the jaw.
"We have found that since the vessels more commonly associated with the back of the head are critical to maintaining the perfusion via vascular reorganization, it is essential to visualize these vessels and determine that they are normal pre-operatively," Kumamaru said. "Patients under consideration for face transplantation have universally had some catastrophic defect or injury."
The authors note that the findings could help improve surgical planning and assessment of potential complications in face transplant patients. For instance, previous literature recommends the joining of multiple arteries and veins to ensure adequate blood flow in the facial allograft. However, performing these multiple connections results in longer operation time compared with a single anastomosis.
"Our findings support the simplified anastomosis for full-face transplant procedures that, in turn, can potentially shorten the operative time and reduce procedure-associated complications," Rybicki said.
The results of this study were presented at the annual meeting of the Radiological Society of North America held from Dec. 1 to Dec. 6. The RSNA is an association of more than 53,000 radiologists, radiation oncologists, medical physicists and related scientists, promoting excellence in patient care and health care delivery through education, research and technological innovation.