Lakers coach Phil Jackson underwent an angioplasty Saturday for a severely blocked artery and might miss Game 4 of the Western Conference semifinals against San Antonio today.

Jackson had experienced tightness and pain in his chest for about a week. The procedure cleared what was more than 90 percent blockage in his left anterior descending artery, and a stent was placed into the artery to keep it clear.

Jackson missed Lakers practice Saturday and was expected to remain at Centinela Hospital Medical Center overnight before tests this morning determine if he will coach today.

"If the other tests look fine, he'll be released," Lakers spokesman John Black said. "Optimistically, what we're all hoping for is obviously that he'll be at the game. He'll be on medication for several months, but if all goes well, he'll be able to coach the game."