Hypertension: JNC/ACC-AHA Guidelines and Stepped Therapy

Clinical meaning

Hypertension is the sustained elevation of systemic arterial blood pressure resulting from increased cardiac output, increased systemic vascular resistance (SVR), or both. The 2017 ACC/AHA guidelines redefined hypertension categories: NORMAL (<120/<80 mmHg), ELEVATED (120-129/<80 mmHg), STAGE 1 HYPERTENSION (130-139/80-89 mmHg), and STAGE 2 HYPERTENSION (≥140/≥90 mmHg). This represented a significant change from the previous JNC 7 threshold of ≥140/90. PRIMARY (essential) hypertension accounts for 90-95% of cases and results from complex interactions between genetic predisposition, sympathetic nervous system overactivity, the renin-angiotensin-aldosterone system (RAAS), endothelial dysfunction, and environmental factors (sodium intake, obesity, physical inactivity, stress). SECONDARY hypertension (5-10%) has identifiable causes including renal artery stenosis (renovascular HTN), primary hyperaldosteronism (Conn syndrome), pheochromocytoma, Cushing syndrome, coarctation of the aorta, obstructive sleep apnea, thyroid disease, and medications (NSAIDs, oral contraceptives, decongestants, stimulants). The pathophysiology of sustained hypertension involves: (1) increased SVR from vascular remodeling (smooth muscle hypertrophy, increased collagen deposition, endothelial dysfunction with reduced nitric oxide availability), (2) RAAS activation (angiotensin II causes direct vasoconstriction, aldosterone causes sodium and water retention, and both promote cardiac and vascular remodeling), (3) sympathetic overactivity (increased norepinephrine release, increased heart rate and contractility, renal sodium retention), and (4) renal sodium handling (impaired pressure natriuresis requiring higher pressures to excrete the same sodium load). TARGET ORGAN DAMAGE from uncontrolled hypertension includes: CARDIAC (left ventricular hypertrophy, heart failure with preserved then reduced ejection fraction, coronary artery disease), CEREBROVASCULAR (ischemic and hemorrhagic stroke, TIA, vascular dementia), RENAL (hypertensive nephrosclerosis, CKD, proteinuria), RETINAL (hypertensive retinopathy: arteriolar narrowing, AV nicking, flame hemorrhages, papilledema), and VASCULAR (aortic dissection, peripheral arterial disease, aortic aneurysm). The NP must distinguish hypertensive URGENCY (severely elevated BP without acute target organ damage -- reduce BP gradually over 24-48 hours with oral agents) from hypertensive EMERGENCY (severely elevated BP WITH acute target organ damage -- requires immediate IV therapy and ICU admission with goal to reduce MAP by no more than 25% in the first hour).

Diagnosis & workup

Diagnostics & workup: - Accurate blood pressure measurement: use correct cuff size (bladder encircling ≥80% of arm circumference -- undersized cuffs falsely ELEVATE readings), patient seated with back supported and feet on the floor for 5 minutes, arm supported at heart level, no talking; average of 2-3 readings on 2-3 separate occasions before diagnosing hypertension; ambulatory blood pressure monitoring (ABPM) or home BP monitoring is recommended to confirm diagnosis and exclude white coat hypertension - Initial laboratory workup for all newly diagnosed hypertension: BMP (creatinine, eGFR, potassium, sodium, glucose, calcium), urinalysis with urine protein-to-creatinine ratio, lipid panel, fasting glucose or HbA1c, TSH, CBC; these labs screen for target organ damage, secondary causes, and comorbidities that influence drug selection - 12-lead ECG: screen for left ventricular hypertrophy (LVH -- Sokolow-Lyon criteria: S in V1 + R in V5 or V6 ≥35 mm; Cornell criteria: R in aVL + S in V3 ≥28 mm in men, ≥20 mm in women), prior MI, arrhythmias (especially atrial fibrillation), and conduction abnormalities; LVH is a significant finding indicating target organ damage - Secondary hypertension screening (when indicated): order when hypertension develops before age 30, is resistant to 3+ drugs, abruptly worsens, or is accompanied by hypokalemia (primary hyperaldosteronism screen: aldosterone-to-renin ratio), labile BP with episodic headache/diaphoresis/palpitations (pheochromocytoma screen: plasma free metanephrines), renal bruit or asymmetric kidneys (renovascular HTN: renal artery duplex ultrasound), cushingoid features (Cushing screen: 24-hour urine cortisol or overnight dexamethasone suppression test) - 10-year ASCVD risk calculation: use the Pooled Cohort Equations (ACC/AHA) to calculate 10-year atherosclerotic cardiovascular disease risk; this determines the treatment threshold for Stage 1 hypertension (130-139/80-89): pharmacotherapy is recommended if 10-year ASCVD risk ≥10% OR if the patient has clinical CVD, diabetes, or CKD; lifestyle modification alone if risk <10% - Echocardiography (when indicated): assess for LVH (wall thickness, LV mass index), diastolic dysfunction (tissue Doppler, E/e' ratio), and systolic function (ejection fraction); indicated when ECG suggests LVH, when heart failure is suspected, or when hypertensive cardiomyopathy is being evaluated

Risk factors: - Age ≥55 years for men, ≥65 years for women: arterial stiffness from loss of elastic fibers and increased collagen in the aorta and large arteries leads to isolated systolic hypertension (elevated systolic with normal or low diastolic), the most common hypertension pattern in elderly - Family history of hypertension: genetic factors account for 30-50% of blood pressure variation; polygenic inheritance involving genes affecting RAAS, renal sodium handling, sympathetic nervous system, and vascular tone; patients with both parents hypertensive have a ~50% lifetime risk - Excessive sodium intake (>2300 mg/day): salt sensitivity (exaggerated BP response to sodium intake) is present in ~50% of hypertensive patients and is more common in African Americans, elderly, and patients with CKD; the DASH diet (Dietary Approaches to Stop Hypertension) reduces BP by 8-14 mmHg - Obesity (BMI ≥30): visceral adiposity increases sympathetic tone, activates RAAS, causes insulin resistance (hyperinsulinemia promotes sodium retention), and creates mechanical compression of the kidneys; each 10 kg weight loss reduces BP by approximately 5-20 mmHg - Physical inactivity: regular aerobic exercise reduces BP by 4-9 mmHg through multiple mechanisms (reduced sympathetic activity, improved endothelial function, decreased vascular stiffness, weight management) - African American race/ethnicity: hypertension is more prevalent, develops earlier, is more severe, and causes more target organ damage in African Americans; salt sensitivity is more common; pharmacological response differs (ACE inhibitors and ARBs are less effective as monotherapy compared to CCBs and thiazide diuretics) - Chronic kidney disease: both a cause and consequence of hypertension; reduced GFR impairs sodium excretion, activates RAAS, and increases sympathetic activity; hypertension accelerates CKD progression; aggressive BP control (target <130/80) slows CKD progression

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