A blood pressure check may be one of the most tried and true routines of a visit to the doctor's office. But a group of Allina Health doctors in Edina is challenging the reliability of the conventional test and is trying a new method they believe could provide a more accurate diagnosis for thousands of patients who suffer from hypertension. While few doubt that routine checks help millions of Americans control their high blood pressure, there is growing evidence that these point-in-time readings overdiagnose some patients — people whose numbers go up at the doctors' office simply because of nerves — while underdiagnosing others whose hidden hypertension puts them at greater risk for stroke and heart disease.