High blood pressure, like a speeding car nearing a bend, must be brought under control before a deadly crash occurs.

With high blood pressure, that crash can include a stroke, heart attack or kidney failure.

Hazel Cloe Dailey, 69, of Paden City, W.Va., said she knew she needed help when her blood pressure peaked at 310/159 mmHg. Compare that with the norm of 120/80, with the American Heart Association defining hypertension as a reading of 140/90 or higher.

"I've had blood pressure problems since I was 58, but not always that severe," Mrs. Dailey said, describing typical readings of 200/100.

But chronically high numbers, despite a full battery of medications, have put Mrs. Dailey atop the list for an experimental procedure at Allegheny General Hospital that's shown promise in lowering blood pressure. No medication is required, but the goal is to lower blood pressure so it can be stabilized fully with hypertension medications.

Mrs. Dailey will undergo a three- to four-hour procedure today to implant a pacemaker-size device below her collarbone with electrodes leading to barroreceptors in the carotid artery of the neck. The battery-operated device known as the Rheos Hypertension System will stimulate those barroreceptors so they signal the heart, blood vessels and kidneys to put the brakes on blood pressure.

In European trials, the system developed by CVRx Inc. of Minneapolis reduced blood pressure by an average of 39 mmHg systolic (peak number) and 26 mmHg diastolic.

AGH is one of 25 sites nationwide, and the only one in Western Pennsylvania, involved in the clinical trial in which a total of 300 patients will see if their results are as promising as those in European trials.

Dr. Satish Muluk, AGH director of the division of vascular surgery and the hospital's principal investigator in the clinical trial, said the procedure, if proven safe and effective, could be used eventually in people with less severe problems. "We don't anticipate it will totally cure the problem, but we can get it under a better degree of control," Dr. Muluk said.

Dr. Srinivas Murali, director of AGH's division of cardiovascular medicine, said up to 25 percent of patients with high blood pressure suffer resistance that makes it more challenging to control blood pressure with medications.

For Mrs. Dailey, the Rheos system is her only remaining alternative to stabilizing her blood pressure.

She said she's not nervous because of the ordeal she's undergone with her health that includes treatment for thyroid problems, sleep apnea, diabetes and high cholesterol, all of which contribute to high blood pressure.

Currently she's taking 12 prescriptions -- 27 pills a day -- many for blood pressure. New medications she's tried work for a while, then resistance sets in, Dr. Murali said.

"We do encounter this on occasion," he said. "Uncontrolled high blood pressure is very serious. It puts a very high risk of congestive heart failure, heart attack and strokes and leads to life-threatening consequences, so it is important to have high blood pressure controlled tightly."

He said the heart, brain and kidneys "bear the brunt" of problems from hypertension, with resistance to medications becoming a growing problem.

Some 75 million Americans suffer hypertension with upward to 19 million lacking full control due to resistance.

The Rheos Hypertension System is expected to show results in as early as 10 days, with incremental improvements over a year. A person would need to use the implant for a lifetime.