Houston surgeons successfully implanted a pacemaker in former Polish President Lech Walesa on Friday and hope it will keep the Nobel laureate from needing a heart transplant.

The device was implanted during a two-hour hour procedure at Methodist DeBakey Heart and Vascular Center. Doctors said the 64-year-old Walesa was doing well.

"This is a tool that can improve his heart function to the point that we can avoid going to transplant," Dr. Miguel Valderrabano said before the procedure.

Walesa came to Houston for tests this week and had a stent implanted into a clogged coronary artery on Wednesday. Among his symptoms were chest pain, fatigue and shortness of breath, doctors had said.