Hypertension

Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. The disorder can usually be managed with lifestyle modification and medications, but occasionally, vascular intervention or surgery are required. Age, sex, smoking, obesity, and diet are contributing factors to hypertension, which can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. Many individuals with hypertension are undiagnosed or undertreated.

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Overview

Definition

Hypertension is defined as a BP > 130/80 mm Hg.

  • Primary (essential) hypertension is the most common type of hypertension; it has no known cause.
  • Secondary hypertension is due to another medical condition or to medications.

Epidemiology

  • Prevalence depends on the definition of hypertension.
  • In 2017, the American College of Cardiology/American Heart Association (ACC/AHA) lowered the threshold for the definition of hypertension, with prevalence now 43%–50% in adults. 
  • More common in older adults, men, and Black patients

Etiology

Primary hypertension:

The pathogenesis of primary hypertension is poorly understood but is most likely the result of numerous genetic and environmental factors affecting cardiovascular and kidney structure and function. Risk factors:

  • Male sex
  • Advanced age
  • Family history
  • Race
  • Smoking
  • Alcohol consumption
  • Obesity
  • Diet high in sodium
  • Physical inactivity

Secondary hypertension:

  • Medications (oral contraceptives, NSAIDs, antidepressants, steroids, stimulants)
  • Illicit drugs
  • Renal: primary kidney disease, renovascular
  • Obstructive sleep apnea
  • Endocrine: pheochromocytoma, primary aldosteronism, Cushing syndrome, Graves’ disease
  • Coarctation of the aorta

Classification

Table: Classification of hypertension (2017 JNC 8 guidelines)
BP categorySystolic BP (mm Hg)Diastolic BP (mm Hg)
Normal BP< 120 mm HgAND< 80 mm Hg
Elevated BP120–129 mm HgOR< 80 mm Hg
Stage 1 hypertension130–139 mm HgOR80–89 mm Hg
Stage 2 hypertension≥ 140 mm HgOR≥ 90 mm Hg
JNC 8: Eighth Joint National Committee

Clinical Presentation

General features

  • Most often presents with no signs or symptoms
  • Can present with headache, epistaxis, tinnitus, or dizziness

Subtypes

  • Isolated office hypertension (“white-coat hypertension“): characterized by measurements ≥ 130/80 mm Hg in the physician’s office, while measurements taken at home and during BP monitoring are normal
  • Isolated ambulatory hypertension (“masked hypertension”):
    • Increased systolic BP (≥ 140 mm Hg) with diastolic BP within normal limits (≤ 90 mm Hg)
    • Masked uncontrolled hypertension (MUCH) is diagnosed in patients treated for hypertension who are normotensive in the clinic but hypertensive outside.

Diagnosis

Medical history and physical examination

  • Prior to diagnosing hypertension, it is important to use an average based on ≥ 2 readings obtained on ≥ 2 occasions.
  • Diagnosis of hypertension should be confirmed using out-of-office BP measurement whenever possible.
  • In uncommon scenarios, diagnosis can be made if a patient presents with hypertensive urgency, ≥ 180 mm Hg systolic or ≥ 120 mm Hg diastolic, or an initial screening BP ≥ 160 mm Hg systolic or ≥ 100 Hg diastolic and known target end-organ damage (e.g., left ventricular hypertrophy, hypertensive retinopathy, or hypertensive kidney disease).
  • In cases of white-coat hypertension: ambulatory BP monitoring (ABPM) over a period of 24 hours is appropriate.

Laboratory

  • Hb and Hct: may indicate anemia due to underlying renal disease
  • Creatinine and eGFR levels: to evaluate renal function
  • Potassium levels: useful when Conn’s syndrome suspected
  • T3, T4, thyroid-stimulating hormone (TSH), aldosterone, and renin: to evaluate for the presence of endocrine hypertension
  • Urinalysis: Microalbuminuria may be an early indicator of renal damage, especially in diabetic patients.
  • 24-hour urine for catecholamines/metanephrines: if diastolic BP > 110 mm Hg, levels 2× upper limit of normal indicate pheochromocytoma

Electrocardiography

Evaluates for left ventricular hypertrophy (LVH): strain pattern often seen with hypertensive heart disease

  • Increased R-wave amplitude in V5, V6, I, and aVL
  • Increased S-wave amplitude in V1 and V2
  • Compensatory ST-segment and T-wave changes
STE secondary to left ventricular hypertrophy

ECG showing left ventricular hypertrophy (LVH):
Note exaggerated amplitude of the QRS complexes and abnormal repolarization pattern typical of LVH.

Image: “STE secondary to left ventricular hypertrophy” by Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA. License: CC BY 3.0

Imaging

  • Chest X-ray: useful to determine the presence of cardiomegaly, aortic coarctation
  • Echocardiography: evaluate for LVH, impaired systolic and/or diastolic function, valvular dysfunction/deformity
  • Renal duplex ultrasound: if renovascular hypertension suspected

Management

Nonpharmacologic measures

  • Weight reduction: ideally, BMI ≤ 25
  • Low-sodium diet: ≤ 2300 mg/day
  • Mediterranean diet: rich in fruits, vegetables, whole grains, low-fat dairy foods, and olive oil
  • Smoking cessation
  • Limit consumption of alcohol and coffee to 2 per day.
  • Regular physical activity: 30 minutes 5 days a week

Medical management

Table: Pharmacologic management of hypertension
Pharmacologic classUseAvoid in
Thiazide diuretics1st-linePatients with gout, pregnancy, and electrolyte disorders
β-blockersPrior MI, stable angina, chronic heart failure, atrial arrhythmiasHeart block, sick sinus syndrome, COPD, asthma, acute heart failure
ACEisHeart failure, diabetes, unstable angina, MI, kidney diseasePregnancy, renovascular hypertension, angioedema
ARBsHeart failure, diabetes, kidney diseasePregnancy, renovascular hypertension
Calcium channel blockersAtrial tachyarrhythmias, Raynaud syndromeHeart block, sick sinus syndrome, pregnancy, heart failure
Aldosterone receptor blockersPrior MI, heart failurePregnancy, hyperkalemia
COPD: chronic obstructive pulmonary disease

Clinical Relevance

Hypertension is a risk factor for atherosclerosis, which can lead to MI, ischemic heart disease, cerebrovascular accident, and peripheral ischemia.

Other conditions associated with hypertension include: 

  • Polycystic kidney disease (PKD): can be diagnosed in adults and pediatric patients. Polycystic kidney disease is an inherited disease that involves bilateral renal cysts without dysplasia. There are 2 forms: autosomal recessive and autosomal dominant.
  • Glomerulonephritis: immune-mediated inflammation of the renal glomeruli. Glomerulonephritis can be primary or secondary (due to other diseases). Patients with glomerulonephritis will present with various symptoms, depending on the pathology, but this disorder is commonly associated with hypertension.
  • Hyperparathyroidism: causes increased peripheral vascular resistance because of increased calcium levels with resultant elevation in BP.
  • Hyperaldosteronism: patients present with increased levels of aldosterone, which in turn increases sodium and water reabsorption, causing hypertension. In the adrenocorticotropic hormone (ACTH)–dependent form, androgens may also be increased, and women can experience hirsutism and menstrual disruptions.

References

  1. Basile, J., Block, J. (2021). Overview of hypertension in adults. UpToDate. Retrieved March 18, 2021, from https://www.uptodate.com/contents/overview-of-hypertension-in-adults
  2. Whelton, P.K., Carey, R.M. et al. (2017). ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. https://www.jacc.org/doi/full/10.1016/j.jacc.2017.11.006?_ga=2.178229602.677038771.1616197579-1081973158.1616197579
  3. Unger, T., Borghi, C., Charchar, F., et al. (2020.) International Society of Hypertension Global Hypertension Practice Guidelines. Hypertension 75:1334–1357.

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