Shopping for the best blood pressure monitor? Good for you. It's never too early to start taking a series of easy, accurate readings and monitoring your blood pressure. A recent study in the Journal of the American College of Cardiology found that people who have hig blood pressure, or hypertension, before age 40 are at an increased risk of heart disease later in life. But to know if you have high blood pressure, you need to take a series of measurements with an accurate home monitor, and unless you're a trained professional, manual blood pressure devices may not offer the accuracy you're looking for. And according to the American Heart Association, blood pressure measurement accuracy depends on two things: a properly fitting blood pressure cuff (such as an upper arm or wrist blood pressure monitor) and independent validation