I've been evaluating a wearable wristwatch blood pressure monitor for the last week.
After a Twitter interaction with Omron stimulated by , the Omron people loaned me one of their devices.
Omron's website describes the device as follows:
Engineered to keep you informed, HeartGuide is a wearable blood pressure monitor in the innovative form of a wristwatch. In tandem with its companion app HeartAdvisor, HeartGuide delivers powerful new technology making tracking and managing your blood pressure easier than ever before. Proactively monitor your heart health by turning real-time heart data into heart knowledge and knowledge into action.
I, like the American Heart Association, have not recommended wrist BP devices. My decision was based on my personal research in the 1990s on arterial waveforms and the influence of wave reflection. Studies have clearly shown a change in the arterial wave form as it proceeds from the ascending aorta to the periphery.
Therefore, the Skeptical Cardiologist was skeptical of the value of the HeartGuide.
After wearing the HeartGuide for a week and using it in a variety of situations to measure my blood pressure, I am rethinking my recommendation against wrist blood pressure cuffs.
I'll give my full analysis of the device after more evaluation, but what I've discovered is that it can serve as an accurate and unobtrusive daytime ambulatory blood pressure monitor.
Ambulatory blood pressure monitoring (ABPM) utilizes a portable BP monitor, which includes a brachial BP cuff and a device that inflates the cuff every 20-30 minutes, makes a measurement, and stores all the recordings for offline review.
Studies have shown ABPM is a better predictor of CV mortality than either clinic BP or home BP monitoring. It has not been widely utilized in the U.S. because it is poorly reimbursed.
The HeartGuide sits on my wrist and, whenever I feel like it, wherever I am, I can quickly and simply make a recording of my BP.
With the HeartGuide I have made BP recordings in a variety of situations that I would never previously have considered.
For example, earlier this week I wore the HeartGuide to work. I measured my BP at home and it was 125/76 mm Hg. After dropping my gear off at my office, I walked to the 6th floor of the hospital to see inpatients. This involved going down several flights of stairs, crossing to the hospital via a pedestrian walkway, and climbing several flights of stairs.
When I emerged on the 6th floor, I stopped (because the HeartGuide does not like it if you are moving), triggered the HeartGuide, and put my right hand over my heart (the device likes you to put your hand on your heart). Within 90 seconds, I knew my BP had increased to 143/81.
In order to do this unobtrusively, I wandered into the patient waiting area and pretended to be watching NFL highlights on the TV. Nobody seemed to notice I was taking my BP!
Subsequently, I was paged to do a transesophageal echo/electrical cardioversion and went downstairs to our "heart station" where a room full of RNs, a sonographer, an anesthetist, and a patient awaited me. While talking to the patient about the procedure, I triggered the HeartGuide and made another BP recording. Nobody noticed!
The HeartGuide BPs are displayed on the watch face for a few seconds and can be sent via Bluetooth to the HeartAdvisor smartphone app.
The graph above shows my BP was high at 8:07 a.m. while I was talking to the patient and still up after the procedure.
One day, I wore the HeartGuide to the gym and made BP measurements under a variety of conditions.
The HeartGuide would not activate while I was walking on the treadmill no matter how hard I tried to keep my arm still. It does not like motion of any kind.
But the first reading on the left was immediately after running on the treadmill. I then performed an isometric leg press hold on a weight machine and was able to obtain a recording during this maneuver of 140/88. Shortly after the leg press, I repeated the recording, and it had dropped down to 104/69.
I have to say this is an abundance of BP information that is quite interesting and heretofore I had never been aware of. It opens up intriguing clinical possibilities.
I will have to spend more time analyzing the HeartGuide before writing my overall impression and recommendations; but thus far, I see it expanding our toolkit for understanding hypertension and personalizing cardiovascular medicine.
Try to imagine yourself standing like me outside a restaurant unobtrusively taking your blood pressure and ponder the possibilities!
Soon you may find that wherever you go, you're in the know. But be aware of the possibility of being arrested for loitering while checking your BP.
If you'd like to read a detailed description of the HeartGuide, check out this while eagerly awaiting my more serious and more complete analysis.
, is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke's Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at , where a version of this post first appeared.