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Beyond office sphygmomanometry: Ways to better assess blood pressure

Cleveland Clinic Journal of Medicine. 2009 November;76(11):657-662 | 10.3949/ccjm.76gr.0409
November 1, 2009|Cleveland Clinic Journal of Medicine
Mohammad Rafey, MD
Author and Disclosure Information

Mohammad Rafey, MD
Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic

Address: Mohammad Rafey, MD, Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Q7, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; e-mail rafeym@ccf.org

Medical Grand Rounds articles are based on editorial transcripts from Education Institute Department of Medicine Grand Rounds presentations at Cleveland Clinic. They are approved by the author but are not peer-reviewed.

ABSTRACTTo diagnose and manage hypertension optimally, we may need to do more than measure the patient’s blood pressure in the office using traditional sphygmomanometry. A variety of devices—some already available, validated, and reimbursable, some still in development—provide more information and give us a better picture of the patient’s true hypertensive status, degree of blood pressure control, and risk of end-organ damage.

KEY POINTS

  • Traditional office blood pressure measurements have diagnostic limitations, since they are only snapshots of a very dynamic variable.
  • Ambulatory 24-hour blood pressure monitoring is a useful and proven tool and can reveal nocturnal hypertension, a possible new marker of risk.
  • Automatic devices can be used in the clinician’s office to minimize the “white coat effect” and measure blood pressure accurately.
  • Pulse-wave analysis provides physiologic data on central blood pressure and arterial stiffness. This information may help in the early identification and management of patients at risk for end-organ damage.

USING THE INTERNET IN MANAGING HYPERTENSION

Green et al22 studied a new model of care using home blood pressure monitoring via the Internet, and provided feedback and intervention to the patient via a pharmacist to achieve blood pressure goals. Patients measured their blood pressure at home on at least 2 days a week (two measurements each time), using an automatic oscillometric monitor (Omron Hem-705-CP, Kyoto, Japan), and entered the results in an electronic medical record on the Internet. In the intervention group, a pharmacist communicated with each patient by either phone or e-mail every 2 weeks, making changes to their antihypertensive regimens as needed.

Patients in the intervention group had an average reduction in blood pressure of 14 mm Hg from baseline, and their blood pressure was much better controlled compared with the control groups, who were being passively monitored or were receiving usual care based on office blood pressure readings.

MEASURING ARTERIAL STIFFNESS TO ASSES RISK OF END-ORGAN DAMAGE

Mean arterial blood pressure, derived from the extremes of systolic and diastolic pressure as measured with a traditional sphygmomanometer, is a product of cardiac output and total peripheral vascular resistance. In contrast, central aortic blood pressure, the central augmentation index, and pulse wave velocity are measures derived from brachial blood pressure as well as arterial pulse wave tracings. They provide additional information on arterial stiffness and help stratify patients at increased cardiovascular risk.

The art of evaluating the arterial pulse wave with the fingertips while examining a patient and diagnosing various ailments was well known and practiced by ancient Greek and Chinese physicians. Although this was less recognized in Western medicine, it was the pulse wave recording on a sphygmograph that was used to measure human blood pressure in the 19th century.23 In the early 20th century, this art was lost with the invention of the mercury sphygmomanometer.

Figure 2.
With age or disease such as diabetes or hypercholesterolemia, arteries gradually lose their elastic properties and become larger and stiffer. With each contraction of the left ventricle during systole, a pulse wave is generated and propagated forward into the peripheral arterial system. This wave is then reflected back to the heart from the branching points of peripheral arteries. In normal arteries, the reflected wave merges with the forward-traveling wave in diastole and augments coronary blood flow.24 In arteries that are stiff due to aging or vascular comorbidities, the reflected wave returns faster and merges with the forward wave in systole. This results in a higher left ventricular afterload and decreased perfusion of coronary arteries, leading to left ventricular hypertrophy and increased arterial and central blood pressure (Figure 2).

Arterial stiffness indices—ie, central aortic blood pressure, the central augmentation index, and pulse wave velocity—can now be measured noninvasively and have been shown to correlate very well with measurements obtained via a central arterial catheter. In the past, the only way to measure central blood pressure was directly via a central arterial catheter. New devices now measure arterial stiffness indices indirectly by applanation tonometry and pulse wave analysis (reviewed by O’Rourke et al25).

Several trials have shown that these arterial indices have a better prognostic value than the mean arterial pressure or the brachial pulse pressure. For example, the Baltimore Longitudinal Study of Aging26 followed 100 normotensive individuals for 5 years and found that those with a higher pulse wave velocity had a greater chance of developing incident hypertension. Other studies showed that pulse wave velocity and other indices of arterial stiffness are associated with dysfunction of the microvasculature in the brain, with higher cardiovascular risk, and a higher risk of death.

A major limitation in measuring these arterial stiffness indices is that they are derived values and require measurement of brachial blood pressure in addition to the pulse wave tracing.

Recent hypertension guidelines21,27,28 released during the past 2 years in Europe, Latin America, and Japan have recommended measurement of arterial stiffness as part of a comprehensive evaluation of patients with hypertension.

EXCITING TIMES IN HYPERTENSION

These are exciting times in the field of hypertension. With advances in technology, we have new devices and techniques that provide a closer view of the hemodynamic changes and blood pressures experienced by vital organs. In addition, we can now go beyond the physician’s office and evaluate blood pressure changes that occur during the course of a usual day in a patient’s life. This enables us to make better decisions in the management of their hypertension, embodying Dr. Harvey Cushing’s teaching that the physician’s obligation is to “view the man in his world.”29

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