Hipertensi Esensial

01Pathophysiology

Essential hypertension develops from the interplay of multiple physiologic systems, none of which alone accounts for the disease. Understanding these mechanisms is critical because vignettes often test why a certain drug class works for a given patient.

Increased peripheral vascular resistance is the hemodynamic hallmark. In early stages, cardiac output may be elevated, but over time the sustained pressure leads to vascular remodeling: smooth muscle hypertrophy and endothelial dysfunction cause arteriolar thickening, which further raises resistance. This creates a self-perpetuating cycle.

The renin-angiotensin-aldosterone system (RAAS) plays a central role. Renin from the juxtaglomerular cells converts angiotensinogen to angiotensin I, which ACE then converts to angiotensin II. Angiotensin II is a potent vasoconstrictor and stimulates aldosterone secretion, promoting sodium and water retention. This is why ACE inhibitors and ARBs are so effective: they interrupt this cascade directly.

Sympathetic nervous system overactivity raises heart rate and contractility while constricting peripheral vessels. Chronic sympathetic tone also stimulates renin release, linking this pathway to RAAS activation. This connection explains why beta-blockers reduce blood pressure partly through renin suppression.

Sodium sensitivity and volume expansion contribute significantly, particularly in Black patients and the elderly, where low-renin, volume-dependent hypertension predominates. Excess dietary sodium leads to water retention, expanding intravascular volume and raising preload. This is the mechanistic basis for the effectiveness of thiazide diuretics and calcium channel blockers in these populations.

Endothelial dysfunction reduces nitric oxide bioavailability, impairing vasodilation. The resulting oxidative stress and vascular inflammation accelerate atherosclerosis, linking hypertension to coronary artery disease, stroke, and chronic kidney disease. This explains why hypertension is more than just a number: it is an active vascular disease.

Genetic factors account for approximately 30-50% of blood pressure variability. Polygenic inheritance patterns mean no single gene is responsible, but family history remains one of the strongest predictors. Exam vignettes often include family history as a contextual clue pointing toward essential rather than secondary hypertension.

The net result of all these mechanisms is sustained elevation of mean arterial pressure (MAP), calculated as:

$$MAP=DBP+\frac{1}{3}(SBP-DBP)MAP\; =\; DBP\; +\; \backslash frac\{1\}\{3\}(SBP\; -\; DBP)$$

Over years, elevated MAP causes target organ damage: left ventricular hypertrophy, retinopathy, nephrosclerosis, and cerebrovascular disease. These are the complications that vignettes test as downstream consequences of untreated hypertension.

02Classification and Clinical Manifestation

Blood Pressure Classification (ACC/AHA 2017 Guidelines)

Hypertensive Crisis Subtypes

Target Organ Damage Manifestations

A critical exam concept: hypertensive retinopathy grading. Grade III (hemorrhages and exudates) and Grade IV (papilledema) indicate malignant hypertension and constitute a medical emergency.

03Diagnostic Workup

The best initial test is a properly performed office blood pressure measurement. The key word here is "properly performed": the patient should be seated quietly for 5 minutes, feet flat on the floor, arm supported at heart level, using an appropriately sized cuff. Blood pressure must be elevated on at least two separate visits before a diagnosis is made. A single elevated reading is insufficient.

When office readings are borderline or when white coat hypertension is suspected (a patient who is normotensive at home but hypertensive in the clinic), ambulatory blood pressure monitoring (ABPM) is the gold standard confirmatory test. ABPM records BP at regular intervals over 24 hours and provides daytime, nighttime, and overall averages. It also identifies masked hypertension, where office readings are normal but out-of-office readings are elevated. This distinction matters because both white coat and masked hypertension carry different prognostic implications.

Home blood pressure monitoring (HBPM) is an acceptable alternative to ABPM and more practical in many settings.

Once hypertension is confirmed, the next step is to evaluate for target organ damage and rule out secondary causes. This is done with a basic metabolic panel (look for elevated creatinine suggesting nephrosclerosis, hypokalemia suggesting primary aldosteronism), urinalysis (proteinuria indicating nephropathy), a lipid panel, fasting glucose, and a 12-lead ECG.

On ECG, look for signs of left ventricular hypertrophy: increased QRS voltage (Sokolow-Lyon criteria: $S_{V1}+R_{V5\text{ or }V6}\ge 35S\_\{V1\}\; +\; R\_\{V5\; \backslash text\{\; or\; \}\; V6\}\; \backslash geq\; 35$ mm) and ST-T wave changes in the lateral leads ("strain pattern"). If LVH is suspected on ECG, an echocardiogram is the most accurate test to confirm it and quantify LV mass.

Further workup for secondary hypertension (plasma aldosterone-to-renin ratio, renal artery duplex, 24-hour urine catecholamines, dexamethasone suppression test) is reserved for patients with clinical red flags: onset before age 30, resistant hypertension (uncontrolled on 3 drugs including a diuretic), sudden onset, hypokalemia, or paroxysmal symptoms.

04Management and Treatment

Summary Table

First-Line Antihypertensive Agents

Lifestyle modifications are the foundation for every patient, regardless of stage. The tested components include:

• DASH diet (Dietary Approaches to Stop Hypertension): rich in fruits, vegetables, whole grains, low-fat dairy; low in saturated fat. Reduces SBP by approximately 8-14 mmHg.

• Sodium restriction: target < 2,300 mg/day (ideally < 1,500 mg/day). Reduces SBP by approximately 2-8 mmHg.

• Weight loss: each kg of body weight lost reduces SBP by roughly 1 mmHg.

• Physical activity: 150 minutes/week of moderate-intensity aerobic exercise (e.g., brisk walking). Reduces SBP by approximately 4-9 mmHg.

• Alcohol moderation: no more than 2 drinks/day for men, 1 drink/day for women.

• Smoking cessation: does not directly lower BP but substantially reduces overall cardiovascular risk.

Pharmacotherapy initiation depends on the stage and the patient's 10-year atherosclerotic cardiovascular disease (ASCVD) risk score. For Stage 1 with low risk, a 3-6 month trial of lifestyle modifications alone is appropriate. For Stage 1 with high risk or Stage 2, medication should begin immediately.

For Stage 2 hypertension, start with two-drug combination therapy from the outset (typically an ACEi/ARB combined with a CCB or thiazide). This is a frequently tested concept: do not titrate a single drug to maximum before adding a second agent when the starting BP is $\ge \backslash geq$ 20/10 mmHg above goal.

Never combine an ACEi with an ARB. This is a classic exam trap. Dual RAAS blockade increases the risk of hyperkalemia, hypotension, and acute kidney injury without additional cardiovascular benefit.

Population-Based Prescribing

Hypertensive Emergency Management

In a hypertensive emergency, the next best step is always to identify the type of end-organ damage and choose the IV agent accordingly:

05Differential Diagnosis and Distractors

The critical teaching point: any patient under 30 years old, any patient with sudden-onset or resistant hypertension, and any patient with unprovoked hypokalemia should trigger a workup for secondary causes before labeling the diagnosis as essential hypertension.

06Traps and High-Yield Pearls

The single most common way students lose points on essential hypertension questions is failing to recognize the correct treatment based on the patient's comorbidities and demographics. A vignette describing a 55-year-old Black man with newly diagnosed stage 1 hypertension and no other comorbidities is testing whether you know that a thiazide diuretic or CCB is preferred over an ACEi as initial monotherapy. Selecting lisinopril is the classic wrong answer in this context.

Another frequent trap involves pregnancy. A vignette presenting a young woman of childbearing age with hypertension is testing whether you know that ACE inhibitors and ARBs are absolutely contraindicated. The correct choices are labetalol, nifedipine, or methyldopa. If the vignette mentions she is already on an ACEi and discovers she is pregnant, the next best step is to immediately discontinue the ACEi and switch to a safe alternative.

Students also confuse hypertensive urgency with hypertensive emergency. The discriminator is the presence of end-organ damage, not the blood pressure number itself. A patient with a BP of 200/120 and a headache but no papilledema, no encephalopathy, no troponin elevation, and no renal failure has urgency, not emergency. Urgency is treated with oral medications and gradual reduction over 24-48 hours. Emergency requires IV medications and ICU admission.

In aortic dissection, a classic trap is giving nitroprusside before a beta-blocker. Nitroprusside causes reflex tachycardia, which increases aortic shear stress and worsens the dissection. The beta-blocker must go first to blunt the heart rate response before adding vasodilators.

Finally, remember that for Stage 2 hypertension (BP $\ge \backslash geq$ 140/90), guidelines recommend starting with two-drug combination therapy rather than monotherapy. A vignette showing a patient with BP of 162/98 who is being started on a single low-dose medication is testing whether you recognize that combination therapy from the start is the correct approach.

The core competency tested across hypertension questions is your ability to match the right drug to the right patient, recognize when to suspect a secondary cause, and correctly sequence the management of hypertensive emergencies.