Sinai Dialysis Access Center - Our Physicians

Dr. Annous is medical director of the Sinai Dialysis Access Center. He is a graduate of Baylor College of Medicine and has been practicing vascular surgery in Baltimore since 1983. Dr. Annous has more than 30 years, experience in the treatment of dialysis access patients and their complications. 

Dr. Mackrell is the chief of Vascular Surgery at Sinai Hospital of Baltimore. He attended Princeton University and Georgetown Medical School. He completed his surgery training at Cornell Medical Center and his vascular surgery and endovascular fellowship at Greenville Memorial Hospital in Greenville, South Carolina. Dr. Mackrell has had a long-term interest in the creation and maintenance of dialysis access. He has written a chapter called “Hemodialysis Access: Placement and Management of Complications” in the book, Comprehensive Vascular and Endovascular Surgery.

Dr. Ulloa developed a keen interest in dialysis access during his training at the University of Maryland Medical Center, one of the busiest renal transplant centers in the nation. He is a board-certified surgeon who is also fellowship trained in vascular surgery. Dr. Ulloa possesses extensive experience in both open and minimally invasive vascular access. He has presented at multiple national meetings and has authored chapters in vascular textbooks.

Dr. Freiburg has extensive experience in open and endovascular procedures for dialysis access. He completed his general surgery residency at the University of Vermont/ Fletcher Allen Health Care and fulfilled a vascular surgery fellowship at Yale University. Dr. Freiburg earned his undergraduate degree from Washington University in Saint Louis, followed by a medical degree from Loyola University Chicago Stritch School of Medicine.