With the ability to walk, talk and work on Sudoku puzzles, John Richter has come a long way since he collapsed and nearly died a month ago while bicycling in Novato.

"I feel totally normal now," he said. "I feel like I'm probably 95 percent of what I was before the incident and I have plans of being 100 percent."

The Marin Catholic High School football coach has Janet DeMers to thank. An intensive care nurse at Kaiser Permanente Medical Center in San Rafael, she happened to drive by Jan. 3 as Richter lay on Atherton Avenue in the midst of cardiac arrest. She stopped and performed CPR that doctors credit with saving his life, or at least preventing serious brain damage.

"I just think it's a miracle," Richter said. "I know if she wasn't there, I wouldn't be here."

On Jan. 3, Richter, 64, a defensive line coach at Marin Catholic, was about halfway through his routine, 30- to 40-mile bike ride when he collapsed. He has no memory of the fall — or of the previous few days — but his two cracked ribs and the three-inch split in the right side of his helmet tell him he likely fell hard.

When DeMers drove by, Richter was still entangled with his bicycle and a small crowd of passersby had gathered.

"My initial thought process was, 'Oh, he's with friends, he must have fallen off his bike and they're helping,'" she said. "I then realized he was laying on the ground. He wasn't sitting up. At that point I turned around."

When she approached Richter he was still breathing but soon the breaths and his heart beat both stopped.

"His color at that time was not good at all — dusty, kind of gray looking. I pretty much at that time knew that he was going to need chest compressions."

DeMers used simplified CPR procedures that call for rapid, deep presses on the victim's chest without the use of mouth-to-mouth.

The procedure helps maintain partial blood flow until paramedics arrive and is critical in the first few minutes of cardiac arrest, said Dr. Michael Sexton, an emergency physician for Kaiser who treated Richter.

"With every minute that goes by, your chances of survival (without CPR) decrease by 10 percent," he said.

Within minutes, Novato paramedics arrived and shocked Richter's heart back into motion with an electronic defibrillator. They administered medication and inserted a breathing tube.

By sheer coincidence a second Kaiser nurse, Margaret Petrie, also happened upon the scene and assisted medics in reviving Richter.

"It truly wasn't anything anybody else wouldn't have done," Petrie said.

Once Richter arrived at Kaiser, doctors examined his arteries and found they were not blocked. His heart attack was atypical, Sexton said.

"The vast majority of cardiac arrests are in patients who have risk factors — hypertension, cholesterol, diabetes, smoking," he said.

Richter was quickly treated with a cooling therapy to reduce the chance of brain damage.

Five days later, after his condition stabilized, he was transferred to Marin General Hospital, where doctors implanted a permanent defibrillator to help in the event of future cardiac episodes. Richter was sent home after another five days at Marin General and he appears to be recovering quickly.

The hospital care no doubt helped Richter, but the benefits of advanced treatments can be severely limited without the kind of rapid CPR that Richter received, Sexton said.

"Without the up-front, immediate institution of very simple things like hands-only CPR, our chances of being successful with technology are significantly hampered," he said.

DeMers said she was simply following her training.

"I wasn't thinking in any terms of survival," she said. "All I was thinking of was the fact that I had one particular skill. I could do chest compressions, and that was the best choice."

Richter's wife, Pat, said the aid her husband received from strangers at a crucial moment was a "pure miracle."

"A lot of people don't know CPR," she said. "People are afraid of getting involved. The fact (DeMers) wouldn't hesitate I think is pretty awesome and unbelievable."