Blood Pressure Regulation

The renin-angiotensin-aldosterone system (RAAS) maintains long-term blood pressure primarily through which of the following mechanisms?

A 52-year-old man with a 10-year history of hypertension presents with episodic severe headaches, profuse sweating, and palpitations lasting 20–30 minutes. Blood pressure during an episode is 210/120 mmHg; baseline is 160/95 mmHg. Plasma metanephrines are elevated. Which investigation is most appropriate to confirm the diagnosis and localize the lesion?

A 48-year-old woman with resistant hypertension (BP 165/105 mmHg on triple therapy) and hypokalemia (K⁺ 3.1 mEq/L) is suspected to have primary aldosteronism. Plasma aldosterone is elevated at 18 ng/dL (normal <15), and plasma renin activity is suppressed at 0.3 ng/mL/hr (normal 0.6–1.6). Which investigation is most appropriate to confirm the diagnosis?

A 58-year-old man with a 10-year history of essential hypertension presents with a blood pressure of 168/105 mmHg. Which of the following is the most common mechanism responsible for the elevation in his diastolic blood pressure?

A 52-year-old man with a 10-year history of hypertension presents with recent-onset resistant hypertension (BP 165/105 mmHg on triple therapy) and progressive dyspnea. Which finding best distinguishes acute hypertensive crisis with pulmonary edema from chronic hypertensive heart disease with diastolic dysfunction?