Hypertension: A Companion to Braunwald's Heart Disease E-Book

George L. Bakris, Matthew Sorrentino

• Publisher: Elsevier
• Year: 2017
• ISBN:
  9780323508766
• Edition: 3
• Topic: Medicina
• Subtopic: Cardiología

The third edition of Hypertension: A Companion to Braunwald's Heart Disease, by Drs. George L. Bakris and Matthew Sorrentino, focuses on every aspect of managing and treating patients who suffer from hypertensive disorders. Designed for cardiologists, endocrinologists and nephrologists alike, this expansive, in-depth review boasts expert guidance from contributors worldwide, keeping you abreast of the latest developments from basic science to clinical trials and guidelines.

• Features expert guidance from worldwide contributors in cardiology, endocrinology, neurology and nephrology.
• Covers behavior management as an integral part of treatment plans for hypertensives and pre-hypertensives.

• Covers new developments in epidemiology, pathophysiology, immunology, clinical findings, laboratory testing, invasive and non-invasive testing, risk stratification, clinical decision-making, prognosis, and management.
• Includes chapters on hot topics such as hypertension as an immune disease; sleep disorders including sleep apnea, a major cause of hypertension; a novel chapter on environmental pollution and its contribution to endothelial dysfunction, and more!
• Equips you with the most recent guidelines from the major societies.
• Updates sourced from the main Braunwald's Heart Disease text.
• Highlights new combination drug therapies and the management of chronic complications of hypertension.

Section III

Diagnosis and Evaluation

Outline

8. The Environment and High Blood Pressure

9. Office Blood Pressure Measurement

10. Home Monitoring of Blood Pressure

11. Ambulatory Blood Pressure Monitoring in Clinical Hypertension Management

12. White-Coat and Masked Hypertension

13. Renovascular Hypertension and Ischemic Nephropathy

14. Secondary Hypertension: Primary Hyperaldosteronism and Mineralocorticoid Excess States

15. Secondary Hypertension: Pheochromocytoma and Paraganglioma

16. Secondary Hypertension: Sleep Disturbances Including Sleep Apnea

17. Hypertension in Children: Diagnosis and Treatment

8

The Environment and High Blood Pressure

Robert D. Brook

Environmental Risk Factors for High Blood Pressure

Clinical Practice Implications

References

Hypertension is a polygenetic disorder provoked by remediable (e.g., sodium intake) as well as unmodifiable factors (e.g., aging).¹ It accounts for up to half of cardiovascular events and is the leading risk factor for morbidity and mortality worldwide.^1,2 To combat this public health epidemic, a number of lifestyle interventions (e.g., reduced sodium intake) have been extensively studied and proven over the years to effectively lower blood pressure (BP).¹ As such, a central aspect of hypertension management endorsed by all guidelines is to identify and alleviate these established modifiable risk factors in individual patients.¹ Conversely, little attention has been paid to another important as well as potentially remediable contributor to high BP—environmental exposures.³ Mounting evidence supports that colder ambient temperatures, winter season, higher altitudes, excessive noises, and air pollutants are capable of raising BP.³ Although the pressor effects are typically modest (5 to 15 mm Hg), billions of people are impacted on a daily basis. Some exposures also tend to overlap in certain settings such as in cities (e.g., noise plus air pollution) and travel destinations (e.g., high altitude plus cold). The full public health burden of environmental exposures remains to be established. However, it is likely to be enormous given their omnipresent nature. This chapter reviews the evidence linking environmental factors with high BP as well as the implications for clinical practice.³

Environmental Risk Factors for High Blood Pressure

Colder Ambient Temperature and Winter Season

Colder temperatures increase BP over hours to days^3-10 as well as over more prolonged seasonal periods.^11-13 Studies across a wide range of populations and climates have demonstrated an inverse association between BP and ambient temperature during the same and/or preceding few days.^3-10,14-21 In one of the largest studies (n > 500,000) conducted across China, a colder temperature of 10° C was associated with a 5.7 mm Hg increase in systolic BP.¹⁴ The impact was even more robust among older adults, those with smaller body mass indices; but was obviated by household central heating. Systolic BP was also on average 10 mm Hg higher during winter compared with summer. These results resemble our findings among 2078 cardiac rehabilitation patients in Michigan whereby reductions in outdoor temperatures by 10.4° C during the prior 1 to 7 days promoted a 3.6 mm Hg increase in systolic BP.²¹ Moreover, in both studies temperatures below 5° C did not prompt further elevations in BP.^14,21 Similar inverse associations between outdoor temperature and BP have also been reported in other recent studies including patients with cardiovascular disease,¹⁵ individuals living in rural China (e.g., 13% lower hypertension control rate during winter),¹⁶ in a large Dutch population (n = 101,377),¹⁸ and across several locations in Italy.^19,20

Independent effects of both winter season and cold temperatures on BP have been reported. Cold exposures measured using personal monitors were shown to be associated with higher systolic BP levels during the daytime, even after adjusting for changes in daylight hours (i.e., season).¹⁹ Conversely, nighttime BP was higher during summer (i.e., warmer days) compared with winter months in this¹⁹ as well as in a few other studies.^7,20 We recently demonstrated similar findings using personal monitoring. Warmer nights (independent of season) led to higher BP levels several hours later during the following afternoon.¹⁰ Along with a few prior studies,^7,19,20 these observations support that there is a highly complex interrelationship involving several exposure-related factors (time of day, duration, indoor versus outdoor temperature levels) that determine the true nature of the ensuing BP changes.

Brief exposure to cold induces a rapid thermoregulatory vasoconstriction, thus raising BP.⁸ Although the mechanisms responsible for the more persistent pressor responses during winter are likely similar, they may not be entirely identical (Table 8.1).^22-24 Further physiologic adaptations (e.g., lower vitamin D, weight gain, reduced activity, and changes in diet/fluid balance) likely play additional roles. Conversely, changes in other meteorologic factors such as humidity and barometric pressure have not been consistently associated with BP.³

The overall evidence supports that both colder ambient temperatures (over a few hours to days) as well as winter seasons (over more prolonged periods) lead to clinically-meaningful elevations in BP. It is possible that this plays a role in the known increase in cardiovascular events during winter.^25,26 From a clinical standpoint, patients with hypertension should be more c...