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Morning Blood Pressure and Hypertension in Pregnancy

Robert Lee Page II, PharmD, FCCP, FAHA, BCPS, CGP
Published Online: Wednesday, October 1, 2008   [ Request Print ]


Dr. Page is an associate professor of clinical pharmacy and physical medicine and a clinical specialist, Division of Cardiology, University of Colorado Health Sciences Center, Schools of Pharmacy and Medicine.


Morning Blood Pressure and Cardiovascular Events: A Deadly Association

As with many biological processes in the human body, blood pressure (BP) follows a natural circadian rhythm, which can be defined as a predictable-in-time cyclic variability.1 Typically, BP is the lowest during sleep and rises toward the end of the sleep cycle. Upon awakening, a sudden change in posture is followed by systemic increases in catecholamines, cortisol, aldosterone, angiotensin, and plasma renin that accompany physical and psychological stress. Moreover, the body exhibits heightened sensitivity to such changes as evidenced by the lower concentration of epinephrine needed to induce platelet aggregation or vessel vasoconstriction. All of these actions translate to increased heart rate, BP, coronary tone, and vessel caliber.2,3

Types of Morning Hypertension

For patients with high BP, this circadian pattern is no different but may be associated with poor health outcomes. In patients with hypertension, BP follows a nadir occurring during the nighttime hours and a surge occurring during the early morning period (6 AM-12 PM). This phenomenon is referred to as morning hypertension. Two types of morning hypertension exist. Patients who demonstrate persistently high BP from nighttime to morning are referred to as "nondippers," as their BP remains elevated nocturnally. The second type is morning surge hypertension (MSH), which is associated in part with the extreme dips of nocturnal BP. For these hypertensive patients, their nighttime BP is >20% lower than their daytime BP.4-6

Emphasis on HBPM

The importance of morning hypertension has received considerable attention due to the realization that cardiovascular events occur most frequently during the morning hours. Ischemic stroke is 4 times as likely in the morning period, and risk of sudden cardiac death is 70% higher between 7 AM and 9 AM. An hour-by-hour analysis of time for sudden cardiac death demonstrates a 2.5-fold greater risk at 11 AM (peak), compared with the lowest risk at 5 AM.7,8

Long-term consequences in unrecognized and uncontrolled morning hypertension consist of significant end-organ damage, but also metabolic syndrome. Populations at highest risk for morning hypertension are those with diabetes, renal disease, and older adults (>65 years of age). In a study of 519 older patients with hypertension, Kario and colleagues found that those patients with MSH exhibited a higher baseline prevalence of multiple cerebral infarcts (57% vs 33%, P = .001) and a higher incidence of stroke (19% vs 7.3%, P = .004), compared with patients without MSH, respectively.9,10

In patients with or suspected for hypertension, the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nursing Association recommends home blood pressure monitoring (HBPM). Home monitoring supplies valuable, reproducible information regarding morning BP, compared with normal screening in a physician's office.

Furthermore, HBPM provides a better indication of end-organ damage and the effectiveness of drug regimens. Presently, the FDA-cleared BP devices to help detect morning hypertension are manufactured by Omron Healthcare. An up-to-date list of validated monitors is available on the dabl Educational Web site (www.dableducational.org/sphygmomanometers/devices_1_clinical.html#ClinTab) or the British Hypertension Society Web site (www.bhsoc.org/blood_pressure_list.stm).

As pharmacists, it is important to identify patients who merit HBPM. Pharmacists also need to counsel patients on the value of HBPM and how to properly use the device.

References
  1. Smolensky MH, Haus E. Circadian rhythms and clinical medicine with applications to hypertension. Am J Hypertens. 2001;14:280S-90S.
  2. Kario K, Schwartz JE, Gerin W, et al. Psychological and physical stress-induced cardiovascular reactivity and diurnal blood pressure variation in women with different work shifts. Hypertens Res. 2002;25:543-551.
  3. Muller JE, Tofler GH, Stone PH. Circadian variation and triggers of onset of acute cardiovascular disease. Circulation. 1989;79:733-743.
  4. Hoshide S, Kario K, Hoshide Y, et al. Associations between nondipping of nocturnal blood pressure decrease and cardiovascular target organ damage in strictly selected community-dwelling normotensives. Am J Hypertens. 2003;16:434-438.
  5. Kario K, Yasui N, Yokoi H. Ambulatory blood pressure monitoring for cardiovascular medicine. IEEE Eng Med Biol Mag. 2003;22:81-88.
  6. Kario K, Shimada K, Pickering TG. Abnormal nocturnal blood pressure falls in elderly hypertension: clinical significance and determinants. J Cardiovasc Pharmacol. 2003;41 Suppl 1:S61-66.
  7. Muller JE, Ludmer PL, Willich SN, et al. Circadian variation in the frequency of sudden cardiac death. Circulation. 1987;75:131-138.
  8. Willich SN, Levy D, Rocco MB, et al. Circadian variation in the incidence of sudden cardiac death in the Framingham Heart Study population. Am J Cardiol. 1987;60:801-806.
  9. Kario K, Pickering TG, Umeda Y, et al. Morning surge in blood pressure as a predictor of silent and clinical cerebrovascular disease in elderly hypertensives: a prospective study. Circulation. 2003;107:1401-1406.
  10. Kario K, Ishikawa J, Pickering TG, et al. Morning hypertension: the strongest independent risk factor for stroke in elderly hypertensive patients. Hypertens Res. 2006;29:581-587.

This communication on the importance of home blood pressure monitoring is supported by Omron Healthcare Inc. It is intended to help pharmacists and their staff understand the importance of home blood pressure monitoring.


Hypertension in Pregnancy: An Emerging Risk for Cardiovascular Disease

Hypertension affects 10% of pregnancies and has been estimated to be a leading cause of both maternal and fetal morbidity and mortality worldwide.1 Hypertension in pregnancy encompasses a wide spectrum of conditions, such as preeclampsia or eclampsia, preeclampsia superimposed on chronic hypertension, chronic hypertension, and gestational hypertension.2 Unfortunately, the diagnosis of this patient population is not straightforward, despite the clearly defined criteria.

Hypertension During Pregnancy

Hypertension in pregnancy has been defined as 2 recordings of a blood pressure (BP) of at least 140/90 mm Hg at an interval of 6 hours. Yet, patients who have a systolic BP of 120 mm Hg to 139 mm Hg and/or a diastolic BP of 80 mm Hg to 89 mm Hg would be considered prehypertensive, according to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.3 This recommendation implies that the diagnostic threshold of 140/90 mm Hg may be high for any population, and even more so for young women of childbearing age. This high threshold could lead to an underestimation of the prevalence of hypertensive disorders of pregnancy.

Nonetheless, the association between hypertension in pregnancy and adverse long-term cardiovascular outcomes has been increasingly recognized within the literature. In the Family Blood Pressure Program Study, women who had been hypertensive during pregnancy had hazard ratios for stroke, coronary heart disease, and hypertension of 2.0, 1.5, and 1.5, respectively, in addition to higher urinary albumin: creatinine ratios after the age of 40, compared with women who had a history of normotensive pregnancies.4 Several factors have been identified that, if concomitant with hypertensive disorders of pregnancy, might increase the risk for long-term cardiovascular disease (CVD), which include severe or recurrent preeclampsia, smoking, parity, preterm delivery, low infant birth weight, and older age at the time of the affected pregnancy.5-8

While not clear-cut, one pathophysiological factor that might underscore this relationship between hypertension in pregnancy and long-term CVD is that hypertensive disorders of pregnancy (preeclampsia, in particular) and CVD share several common risk factors, such as obesity, diabetes, and renal disease.2 Alternatively, hypertension in pregnancy could induce longer-term metabolic and vascular abnormalities, oxidative stress, inflammatory responses, and hypercoagulability that may increase the overall risk of CVD later in life.2 Furthermore, increasing evidence suggests that a history of hypertension during pregnancy is an underrecognized risk factor that could aid early identification of women who are at an increased risk of developing CVD.

Home BP Monitoring Is Crucial

Women with a history of hypertensive pregnancy should be closely monitored for comorbidities and conventional risk factors for CVD. Furthermore, it is crucial that accurate measurement of BP be conducted as part of a comprehensive prenatal care plan so as to detect these types of hypertensive disorders. Early detection impacts both present and future maternal outcomes. The recent joint scientific statement from the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nurses Association has called for patients with or at risk of hypertension, including pregnant women to routinely monitor their BP at home.9

As the most accessible health care provider, pharmacists can educate expectant mothers on the importance of home BP monitoring, assist in helping them choose the most appropriate monitor, and provide instruction on the correct way to use the monitor.

References
  1. Report of the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy. Am J Obstet Gynecol. 2000;183:S1-S22.
  2. Wagner SJ, Barac S, Garovic VD. Hypertensive pregnancy disorders: current concepts. J Clin Hypertens (Greenwich). 2007;9:560-566.
  3. Chobanian AV, Bakris GL, Black HR, et al. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA. 2003;289:2560-2572.
  4. Garovic VD et al. Hypertension in pregnancy is associated with microalbuminuria and cardiovascular events later in life [abstract]. J Am Soc Nephrol 2006;17: 11A.
  5. Croft P, Hannaford PC. Risk factors for acute myocardial infarction in women: evidence from the Royal College of General Practitioners' oral contraception study. BMJ. 1989;298:165-168.
  6. Jonsdottir LS, Arngrimsson R, Geirsson RT, et al. Death rates from ischemic heart disease in women with a history of hypertension in pregnancy. Acta Obstet Gynecol Scand. 1995;74:772-776.
  7. Irgens HU, Reisaeter L, Irgens LM, et al. Long term mortality of mothers and fathers after preeclampsia: population based cohort study. BMJ. 2001;323:1213-1217.
  8. Arnadottir GA, Geirsson RT, Arngrimsson R, et al. Cardiovascular death in women who had hypertension in pregnancy: a case-control study. BJOG. 2005;112:286-292.
  9. Pickering TG, Miller NH, Ogedegbe G, et al. Call to action on use and reimbursement for home blood pressure monitoring: executive summary: a joint scientific statement from the American Heart Association, American Society Of Hypertension, and Preventive Cardiovascular Nursing Association. Hypertension. 2008;52:1-9.

This communication on the importance of home blood pressure monitoring is supported by Omron Healthcare Inc. It is intended to help pharmacists and their staff understand the importance of home blood pressure monitoring for women, especially if they are pregnant.


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