Last November, Robert Hoover learned about a device that tests endothelial function—the elasticity of the lining of blood vessels. He decided, with the help of a private investor, to purchase the device, the Endo-PAT2000, and open Spokane Vascular Testing, in Spokane Valley, in June.

The former medical-equipment salesman then began visiting medical practitioners' offices to inform them about the test and encourage them to refer patients to his diagnostic testing company, at 8817 E. Mission. Hoover says one naturopath he visited, Philip Faler, "expressed high interest in doing the testing."

Hoover says he suggested that Faler join Spokane Vascular Testing as a minority partner and medical director, and Faler agreed to do so. As medical director, Faler oversees testing with the Endo-PAT2000 and offers an interpretation of each test.

Along with physician-referred patients, Spokane Vascular Testing accepts those who've heard about the test on their own and want to have it done. Hoover says the company is performing about eight to 10 tests a week, and about 60 percent have come to its office on their own without referrals. Spokane Vascular Testing charges $375 for the test.

"Most major insurance covers the test. We haven't run into any that say no. Some plans require other risk factors, like high blood pressure or poor cholesterol," Hoover says.

Hoover says the importance of endothelial function has been known for 20 years. Patients with cardiovascular disease, diabetes, or hypertension often have endothelial dysfunction, which means their blood vessels have a decreased ability to dilate in response to a given stimulus. More recently, however, researchers have found that seemingly healthy people, like athletes who die unexpectedly from heart attacks, may do so because their endothelium, the thin layer of cells lining the interior surface of blood vessels, is not functioning properly, he says.

Spokane Vascular Testing's Web site describes a seven-year study that was done at the Mayo Clinic in Rochester, Minn., using the Endo-PAT.

Three of the Mayo Clinic researchers published a paper in the medical journal Biomark Med in June that says "traditional CV (cardiovascular) risk factors fail to predict the development of coronary heart disease in 25 to 50 percent of cases. ... Endothelial dysfunction ... may serve as the missing link between CV risk factors and atherosclerotic disease," or hardening of the arteries. "Endothelial function measurements may aid in future prediction of CV events and help identify high-risk patients for targeted therapy as well as provide a primary therapeutic end-point for clinical follow-up of these patients."

The paper said the Endo-PAT "is emerging as a promising tool in endothelial function measurement and CV risk stratification."

At Spokane Vascular Testing, Hoover or a technician will seat a patient in a recliner chair and place probes on one finger of each hand. The probes are attached by wires to the Endo-PAT device, and other wires attach the device to a laptop computer. A blood pressure cuff is placed on one of the patient's upper arms. When the device is turned on, signals from the finger probes transmit measurements of vascular tone, or the ability of blood vessels to carry blood through the circulatory system, from the many blood vessels in the fingers. The measurements are displayed with a computer screen etching, similar to an echocardiograph that shows the beating of a heart. A five-minute baseline measurement is taken. The patient relaxes and feels nothing unusual during this part of the test.

For the second five minutes of the test, the blood pressure cuff is inflated to the maximum pressure needed to cut off blood flow to the lower arm, and the finger probes continue to measure endothelial response in the test arm and the control arm. The test arm becomes tingly, like it has gone to sleep. Most patients experience mild discomfort during this phase of the test, Hoover says.

For the last five minutes of the test, the blood pressure cuff is removed, and the device measures the response of blood vessels to the resumed blood flow. It then provides a score, which Hoover says is a ratio between how the blood vessels functioned before and after the stress was induced. A ratio of 2.0 or more shows a healthy endothelium. A reading of less than 2.0 signals endothelial dysfunction.

Following the test, Faler explains the results to the client, and an assessment is sent to the referring doctor, if there is one. If the test results in a poor reading and the client doesn't have a referring doctor, Faler, the naturopath, offers treatment recommendations that might include lifestyle changes such as increased exercise and improved diet. He also might prescribe medications such as statins, drugs that are used to lower blood cholesterol levels. In Washington state, naturopaths are licensed to prescribe medication.

Patients also typically would be urged to return in six months for a repeat test to determine whether treatment or lifestyle changes were improving their endothelial function.

The Endo-PAT was approved by the FDA in 2003, and is sold in the U.S. by Medvica International-Clinical Research Services Inc., of Tucson, Ariz. It is manufactured by Itamar Medical Ltd., in Israel, and costs about $30,000 here. The Endo-PAT has been used in other major clinical studies in the U.S. in Boston, Atlanta, Pittsburgh, and Jackson, Miss., and in Germany, literature from Itamar says. It also is approved for use in Japan and Australia.

Sharon Snyder, CEO of Medvica, says that since the company began distributing the EndoPAT2000 in the U.S. last November, 60 to 70 of the devices have been sold for clinical use.

Hoover says that because the test is still fairly new, physicians he's talked with have been divided on whether it would benefit their patients. He says one Spokane internist has agreed to refer patients to Spokane Vascular Testing, but that physician couldn't be reached for comment. Hoover says some doctors want to see more specific or long-term research on the use of the test. A couple of doctors are doing more reading to educate themselves about the test before they agree to refer patients, he says.

Endothelial function also is tested in hospitals with Doppler ultrasound. One of those tests can cost from $300 to $1,500, depending on its complexity, Hoover says.

Spokane Vascular Testing plans to work with a marketing company to advertise the business to the general public, Hoover says. He also hopes to purchase a second EndoPAT device by the end of this year, and add another technician to do the test. The company then could offer to put on clinics in various locations, possibly charging a reduced fee for the test.

Hoover says he also would like to add other forms of vascular testing, such as a Doppler ultrasound, and eventually would like to sell the Endo-PAT to physicians' offices, but adds, "Doctors' offices aren't buying any equipment right now, so that's on the back burner."