Hypertension is currently defined by the US Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) and World Health Organisation – International Society of Hypertension (WHO/ISH) as systolic blood pressure ≥ 140 mmHg or diastolic ≥ 90 mmHg¹. The Framingham data² show that these levels are present in:
40% of the community over age 50
60% of the community over age 60
90% of the community over age 90

As such, it is the most common medical disorder in our society. New guidelines for treatment refer to the value of using parameters such as those provided by SphygmoCor to complement measured blood pressure values when making decisions for individuals. There has been a strong push for this from the WHO/ISH3 and the working group of the European Society of Hypertension^{4, 5, 6}.

In hypertension management, the SphygmoCor system has unique utility in that it can uncover clinically significant differences in central blood pressures, and central blood pressure profiles, even between patients who have equivalent cuff pressure readings⁷.

The SphygmoCor system is thus a tool for improved hypertension management in that it provides the key cardiovascular data being assessed in making therapy decisions – and monitoring the effectiveness of therapy - for these patients.
 

How SphygmoCor Can Improve Hypertension Management

The SphygmoCor system can improve cardiovascular assessment and associated therapy decisions in hypertension management by providing more precise and specific information about central arterial pressure.

SphygmoCor is of value in determining whether or not to commence therapy for persons with borderline elevation of arterial pressure and evidence of aortic arteriosclerosis, as the degree (or absence) of elevation of central pressures are of heightened relevance in these individuals. Avoidance of therapy – if appropriate – is both a source of potential cost savings and a reduction in patient compliance burden.

Isolated systolic hypertension (ISH), the most common condition requiring intervention at this time, is caused by stiffening of the aorta and large arteries^8,9,10. SphygmoCor is of value in the management of ISH because it provides direct information on aortic systolic pressure (Augmentation Pressure and Augmentation Index). True ISH can be confirmed through measure of significant augmentation of late systolic pressure causing a high late systolic shoulder on the aortic pressure waveform^11,12. These parameters can be monitored periodically so as to determine the central effects of therapy regimen(s).

Spurious systolic hypertension of youth describes substantial elevation of brachial systolic pressure above 140 mmHg - generally due to amplification of the pulse waveform in the upper limb - but with normal or low aortic systolic pressures. It is found in over 10% of adolescent males^11,13,14. In the Framingham offspring study^15,16, such persons were found to have low - not high - cardiovascular risk. No treatment is warranted for these individuals¹⁴. Arterial tonometry is of value to exclude the need for therapy in this condition because it is readily recognized with arterial tonometry, which shows normal aortic pressures and low AIx.

“White coat hypertension” is a phenomenon often apparent when arousal causing catecholamine release leads to increased cardiac output and elevation of brachial arterial pressure but with normal or lowered peripheral resistance^17,18. SphygmoCor shows a dominant initial aortic systolic pressure wave with normal (for age) or reduced AIx, and is therefore of value to exclude the need for therapy in these individuals.

Pseudohypertension is elevated brachial arterial pressure caused by rigidity of tissue in the upper arm such that the pressure applied to the arm by the cuff does not compress the brachial artery19. SphygmoCor can exclude the need for therapy in pseudohypertension as central pressures are normal for age and do not show the expected increased AIx and reduced Tr for evidence of aortic stiffening.

Summary

• Pulse wave analysis with the SphygmoCor system provides a non-invasive means of obtaining and evaluating the ascending aortic blood pressure waveform.

• This information is of value in improving hypertension management, as the central pressure data provided by the SphygmoCor system are critical parameters in managing these patients.
• Use of the SphygmoCor system can facilitate more effective management of isolated systolic hypertension, as well as determination of the necessity of therapy in spurious systolic hypertension of youth, “white coat hypertension”, and pseudohypertension.

References

1. The seventh report of the Joint National Committee of Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA 2003;289:2560-72
2. Vasan RS, Beiser A, Seshadri S, et al. Residual lifetime risk for developing hypertension in middle-aged women and men. JAMA 2002;287:1003-10
3. Chalmers J, MacMahon S, Mancia G, et al. 1999 WHO – International Society of Hypertension Guidelines for the Management of Hypertension. J Hypertens 1999;17:151-83
4. Safar ME. Epidemiological findings imply that goals for drug treatment of hypertension need to be revised. (Editorial) Circulation 2001;103:1188-90.
5. Franklin SS, Wilkinson IB, Cockcroft JR. Does hypertensive cardiovascular risk need redefining? Hypertension 2002
6. Safar ME, London GM for the Clinical Committee of Arterial Structure and Function, on behalf of the Working Group on Vascular Structure and Function of the European Society of Hypertension. Therapeutic studies and arterial stiffness in hypertension: recommendations of the European Society of Hypertension. J Hypertens 2000;18:1527-35.
7. Franklin SS, Larson MG, Khan SA, et al. Does the relation of blood pressure to coronary heart disease risk change with aging? The Framingham Heart Study. Circulation 103(9): 1245-9, 2001.
8. Franklin SS, Wilkinson IB, Cockcroft JR. Does hypertensive cardiovascular risk need redefining? Hypertension 2002.
9. Safar ME, London GM for the Clinical Committee of Arterial Structure and Function, on behalf of the Working Group on Vascular Structure and Function of the European Society of Hypertension. Therapeutic studies and arterial stiffness in hypertension: recommendations of the European Society of Hypertension. J Hypertens 2000;18:1527-35.
10. Izzo JL Jr, Levy D, Black HR. Importance of systolic blood pressure in older Americans. Hypertension 2000;35:1021-24.
11. Nichols WW, O’Rourke MF. McDonald’s blood flow in arteries. 4th Edition. Edward Arnold, London, 1998.
12. Rietzschel ER, De Buyzere ML, Duprez DA, et al. Bypassing complex aortic wave morphology: a simple and direct assessment of aortic augmentation index based on aortic-radial parallelism. (Abstract) Am J Hypertens 2001;14:124A-125A.
13. Mahmud A, Feely J. Spurious systolic hypertension of youth: fit young men with elastic arteries. Am J Hypertens 2003;16:229-32.
14. O’Rourke MF, Vlachopolous C, Graham RM. Spurious hypertension in youth. Vasc Med 5(3):141-5, 2000.
15. Franklin SS, Khan SA, Wong ND, et al. The relation of blood pressure to coronary heart disease risk as a function of age: the Framingham Heart Study. (Abstract) J Am Coll Cardiol. 2000;35:291A.
16. Franklin SS, Larson MG, Khan SA et al. Does the relation of blood pressure to coronary heart disease risk change with ageing? The Framingham Heart Study. Circulation 2001;103:1245-49.
17. Mansour GA, White WB. White coat hypertension. In Hypertension. Oparil S, Weber M (Eds). Philadelphia: Saunders 1996 p314-20.
18. Siegel WV, Blumenthal JH, Devine GW. Physiological, psychological and behavioral factors and white coat hypertension. Hypertension 1990;16:140-46.
19. Messerli FH, Ventura HO, Amodeo C. Osler’s maneuver and pseudohypertension. N Engl J Med 1985;312:1548-51.

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