You know the drill. Traffic is terrible on your way to see your doctor. You are running behind and doing the best you can to get there on time. The parking lot is full and you struggle to find a parking place. When you walk in they remind you that you are a bit late and the nurse whisks you to the back. She sits you down and immediately slaps a blood pressure cuff on your arm and informs you that “you’re blood pressure is awfully high today!”

There is a correct way to measure blood pressure and that isn’t it. Also, the blood pressure method used by virtually every doctor’s office is measuring a brachial (peripheral) blood pressure. It is the pressure in the brachial artery.

However, central blood pressure is a much better assessment of the strain on your heart as well as the risk of cardiovascular disease. Central blood pressure is the pressure in your aorta. It is the pressure your heart actually sees.

Central blood pressure is a better evaluation of your blood pressure than is a doctor’s office blood pressure. It is even better than the 24-hour ambulatory blood pressure monitor evaluation. However, if you have elevated blood pressure then you absolutely need a 24-hour ambulatory blood pressure monitor (ABPM). There are multiple reasons for this addressed on its post.

What is Central Blood Pressure (CBP)?

Central blood pressure is simply the pressure within the ascending aorta, the large artery coming off of the heart which distributes blood to the rest of the body.

Most people are aware of blood pressure as it related to the blood pressure that is checked when you go to your doctor’s office or the Emergency Room. However, the pressure which is generally being measured is the brachial blood pressure, the pressure in the brachial artery. This is referred to as a peripheral blood pressure.

The difference is that central blood pressure is a more accurate reflection of the stress on the heart itself as well as target organ damage (TOD). Target organ damage is the damage that is incurred due to the effect of the pressure on each organ.

Why should you check your Central Blood Pressure?

It is well know that hypertension contributes to cardiovascular disease.6 However, there is a discordance between the brachial blood pressure and central blood pressure.5 We routinely see patients with normal brachial blood pressures and elevated central blood pressures. We’ve also seen it the other way around.

Central blood pressure is a much better predictor of cardiovascular disease mortality, all cause mortality, diastolic heart dysfunction, and left ventricular hypertrophy than brachial blood pressure.

Target Organ Damage

Central blood pressure was checked in 1169 patients using applanation tonometry and SphygmoCor. 319 (27%) had “high-normal” blood pressure. (NOTE: this was prior to the new definitions and these patients had elevated BP or Stage 1 hypertension by the new guidelines). These participants’ blood pressures ranged from 120-139/80-89. Target Organ Damage (TOD) was assessed using Pulse Wave Velocity (PWV), Left Ventricular Mass Indexed to Height (LVMI), or Estimaged Glomerular Filtration Rate (eGFR).

Brachial blood pressures were not able to differentiate patients with target organ damage due to elevated blood pressure. However, central blood pressure values were able to identify target organ damage due to elevated blood pressure. “In contrast to normal versus high-normal BP categories which do not clearly distinguish normotensives with from those without organ damage, noninvasively determined aortic BP measurements may refine the ability to detect those with a normal/high-normal BP at risk of BP-related cardiovascular damage.”10

Central aortic blood pressure & brachial blood pressure enhances the ability to identify cardiovascular target organ damage (TOD). Both 24-hr central blood pressure & 24-hr brachial blood pressure are superior to conventional office BP measurements in predicting BP-related cardiac damage. Additionally, 24-hr central ambulatory blood pressure is more closely associated with left ventricular hypertrophy than 24-hr ambulatory brachial blood pressure.10-12

In other words, it seems that measurements of central blood pressure are always better than brachial blood pressure.

Better evaluation of medication effect

For years, medications have been the mainstay of medical therapy for hypertension. JNC 7 recommended diuretics or beta-blockers as first line therapy. However, neither of these medication classes are the best therapy for reducing target organ damage (TOD) and cardiovascular disease events.

These medications may decrease brachial blood pressure as measured in many of these studies. However, they often don’t have the same effect on central blood pressure. This means that they don’t reduce target organ damage. Additionally, the non-vasodilatory medications, while lowering brachial blood pressure, may actually INCREASE central blood pressure making things even worse!1,2

Heart Remodeling

Hypertension causes left ventricular remodeling. The heart muscle has to work harder due to the increased pressure which causes ventricular remodeling and hypertrophy. Central blood pressure evaluation correlates much better than brachial blood pressure for predicting left ventricular mass (a measure of hypertrophy) as determined by the Strong Heart Study published in the Journal of Hypertension.3

Risk of Death

Another study in the Journal of Hypertension looked at central vs peripheral blood pressures related to cardiovascular and all-cause death. I think it is very interesting that Central pulse pressure (the difference between systolic and diastolic blood pressures) was the only metric correlated to all cause mortality, death for any reason. This is, of course, obtained by measurement of the central blood pressure. However, ambulatory blood pressure (ABPM) is better for predicting cardiovascular mortality.4

Why doesn’t my doctor test this?

If central blood pressure measurements are so much better then why doesn’t my doctor do this?

That is a great question. It hasn’t been until the last year that I’ve seen anyone else check this in their clinic. To my knowledge, there are no other clinics measuring central blood pressure in the entire state of Oklahoma. It is one of the many things that sets our Functional Medicine Tulsa, OK clinic apart from the others.

In the past, central blood pressure could only be measured directly or invasively. This means that we need to insert catheters into the aorta in order to measure central blood pressure. Obviously, there are significant costs and risks associated with this and it wasn’t reasonable in many cases.

However, we now have the ability to measure central blood pressure non-invasively. This will help increase the utilization but these non-invasive devices are still very expensive, well over $10,000. Compare that to a simply blood pressure cuff (less than $100) and you can see why most physicians don’t check it.

How Is Central Blood Pressure Measured?

First, you should be adequately prepared for a proper blood pressure evaluation. Very few clinics actually do this correctly but you should do a few things before getting your blood pressure checked:

• No caffeine within 6 hours
• No exercise the morning of. If your appointment is in the afternoon then morning exercise is fine
• No smoking for 4-6 hours

We use a non-invasive device (no needles or procedures) to check your central blood pressure. A blood pressure cuff will be placed around your arm and the SphygmaCor device will check your blood pressure in the same way as your normal blood pressure check.

It will check your blood pressure a couple of times then the cuff will partially inflate and stay that way for a few seconds then deflate. SphygmaCor then calculates your central blood pressure.

It sounds good but does it actually work?

It does! In fact, it has been validated in several studies when compared to invasively and directly measuring central blood pressure.

One study involved 52 patients who where undergoing invasive procedures also had their central blood pressure checked non-invasively using BPro and SphygmaCor. “cSBP differed by only 0.1±6mmHg (P=.913) between the two noninvasive devices. Therefore, both noninvasive devices showed an accurate agreement in cSBP compared with invasively measured cSBP.”7

This means, of course, that the non-invasive devices tested had the same results as actually measuring the central blood pressure directly. Therefore, central blood pressure as measured by SphygmoCor and BPro are accurate and can be trusted.

Another study evaluated the Pulsecor R6.5 device’s ability to measure central blood pressure in patients undergoing coronary angiography. Their conclusion stated that “Pulsecor R6.5 provides a simple and easy method to non-invasively estimate central SBP, which has highly acceptable accuracy.”8

Yet another study compared radial tonometry to the same types of devices above (i.e. SphygmoCor). Radial tonometry is considered an acceptable “alternative to invasive pressure measurements” in many cases.13 They concluded that the cuff-based non-invasive central blood pressure devices were a good alternative to tonometry. They went on to say that this type of testing “could lead to improved adoption of estimates of central BP in clinical practice.”9

Conclusions

The bottom line is that everyone should be measuring central blood pressure. It is a much better indicator of cardiovascular health and risk of target organ damage (TOD). The problem is that it is still expensive and you may have a very difficult time finding anyone who can measure it.

Unless you come to our Tulsa Functional Medicine Clinic, Revolution Health & Wellness Clinic, for your Executive Cardiovascular Evaluation.

References

1. Hisashi Masugata & Shoichi Senda (2010) Clinical significance of central blood pressure measurement in antihypertensive treatment, Expert Review of Cardiovascular Therapy, 8:6, 763-765, DOI: 10.1586/erc.10.44

2. Williams B, Lacy P, Thom S, Cruickshank K, Stanton A, Collier D, Hughes A, Thurston H, O’Rourke M. Differential Impact of Blood Pressure–Lowering Drugs on Central Aortic Pressure and Clinical Outcomes. Principal Results of the Conduit Artery Function Evaluation (CAFE) Study. Circulation. 2006;113:1213–1225. https://doi.org/10.1161/CIRCULATIONAHA.105.595496

3. Schillaci, Giuseppe; Grassi, Guido. Central blood pressure: getting to the heart of the matter. J of Hypertension 2010;28:237-239. doi: 10.1097/HJH.0b013e3283359509

4. Huang, Chi-Ming; Wang, Kang-Ling; Cheng, Hao-Min; Chuang, Shao-Yuan; Sung, Shih-Hsien; Yu, Wen-Chung; Ting, Chih-Tai; Lakatta, Edward G; Yin, Frank CP; Chou, Pesus; Chen, Chen-Huan. Central versus ambulatory blood pressure in the prediction of all-cause and cardiovascular mortalities. J of Hypertension 2011;29:454-459. doi: 10.1097/HJH.0b013e3283424b4d

5. Alihanoglu Y, Kayrak M, Ulgen M, Yazici M, Yazici M, Yilmaz R, Demir K, Dogan Y, Sizer M, Ozhan H, Koc F, Bodur S. The Impact of Central Blood Pressure Levels on the Relationship Between Oscillometric and Central Blood Pressure Measurements: A Multicenter Invasive Study. J Clin Hypertens (Greenwich). 2013;15:681–686. ©2013 Wiley Periodicals, Inc.

6. Thomopoulos C, Parati G, Zanchetti A. Effects of blood pressure lowering on outcome incidence in hypertension. 1. Overview, meta-analyses, and meta-regression analyses of randomized trials. J Hypertens. 2014 Dec;32(12):2285-95. doi: 10.1097/HJH.0000000000000378.

7. Ott, C. , Haetinger, S. , Schneider, M. P., Pauschinger, M. and Schmieder, R. E. (2012), Comparison of Two Noninvasive Devices for Measurement of Central Systolic Blood Pressure With Invasive Measurement During Cardiac Catheterization. The Journal of Clinical Hypertension, 14: 575-579. doi:10.1111/j.1751-7176.2012.00682.x.

8. Lin, Aaron C.W; Lowe, Andrew; Sidhu, Karishma; Harrison, Wil; Ruygrok, Peter; Stewart, Ralph. Evaluation of a novel sphygmomanometer, which estimates central aortic blood pressure from analysis of brachial artery suprasystolic pressure waves. J of Hypertension 2012;30:1743-1750. doi: 10.1097/HJH.0b013e3283567b94.

9. Park, Chloe M.a; Korolkova, Olgab; Davies, Justin E.a; Parker, Kim H.b; Siggers, Jennifer H.b; March, Katherinea; Tillin, Theresea; Chaturvedi, Nisha; Hughes, Alun D. Arterial pressure: agreement between a brachial cuff-based device and radial tonometry. J of Hypertension 2014;32:865-872. doi: 10.1097/HJH.0000000000000082

10. Booysen, Hendrik L.; Norton G, Maseko, Muzi J.a; Libhaber, Carlos D.b; Majane, Olebogeng H.I.a; Sareli, Pinhasa; Woodiwiss, Angela J. Aortic, but not brachial blood pressure category enhances the ability to identify target organ changes in normotensives. J of Hypertension 2013;31:1124-1130. doi: 10.1097/HJH.0b013e328360802a.

11. Salvi, Paolo; Schillaci, Giuseppe; Parati, Gianfranco. Twenty-four-hour ambulatory central blood pressure: new perspectives for blood pressure measurement? J of Hypertension 2014;32:1774-1777. doi: 10.1097/HJH.0000000000000318.

12. Protogerou, Athanase D; Argyris, Antonis A.a; Papaioannou, Theodoros G.b; Kollias, Georgios E.a; Konstantonis, Giorgos D.a; Nasothimiou, Efthimiaa; Achimastos, Apostolosc; Blacher, Jacquesd; Safar, Michel E.d; Sfikakis, Petros P. Left-ventricular hypertrophy is associated better with 24-h aortic pressure than 24-h brachial pressure in hypertensive patients: the SAFAR study. J of Hypertension 2014;32:1805-1814. doi: 10.1097/HJH.0000000000000263.

13. Weiss BM, Spahn DR, Rahmig H, Rohling R, Pasch T. Radial artery tonometry: moderately accurate but unpredictable technique of continuous non-invasive arterial pressure measurement. Br J Anaesth. 1996 Mar;76(3):405-11.