Personalized Sequential Nephron Blockade for Diuretic Resistance in Acute Decompensated Heart Failure: A Narrative Review for the Cardiorenal Clinician.

Heart failure affects more than 64 million people worldwide, and admissions for acute decompensation account for a substantial proportion of cardiovascular healthcare expenditure. Achieving complete decongestion remains the principal objective of inpatient management, yet many patients are discharged with persistent volume overload, a consistent predictor of early rehospitalization and mortality. Loop diuretics have remained the cornerstone of decongestive therapy for more than six decades; however, their effectiveness is frequently limited by diuretic resistance, leaving many patients incompletely decongested despite dose escalation. Diuretic resistance reflects adaptive sodium retention distributed across multiple nephron segments, a process that extends well beyond the loop itself. Distal-tubular-remodeling-enhanced proximal sodium reabsorption, neurohormonal activation, post-diuretic sodium retention, and impaired tubular drug delivery collectively blunt natriuretic responsiveness, explaining why progressive loop-dose escalation often yields diminishing returns. Sequential nephron blockade provides a physiology-based strategy that matches the adjunct agent to the predominant mechanism of sodium retention. We integrate contemporary randomized evidence with renal tubular physiology to propose a mechanism-based approach: acetazolamide for patients with hypochloremic metabolic alkalosis and enhanced proximal sodium reabsorption, thiazide-type diuretics when distal cotransporter escape predominates, vasopressin antagonists for dilutional hyponatremia complicating congestion, and sodium-glucose cotransporter 2 inhibitors as foundational therapy that combines modest acute natriuresis with durable cardiorenal protection. Early assessment of natriuretic response using spot urine sodium further enables individualized treatment escalation. Together, these concepts move sequential nephron blockade beyond empirical combination diuretic therapy toward a mechanism-based strategy for overcoming diuretic resistance. We propose a personalized, phenotype-driven framework in which early urinary sodium response, kidney function, serum chloride, acid-base status, serum sodium, background SGLT2 inhibitor therapy, and venous congestion imaging guide the selection, escalation, and de-escalation of adjunctive therapy, with the goal of more complete and safer decongestion in acute decompensated heart failure. Matching adjunct choice to a patient's individual biochemical phenotype, rather than applying diuretics in a fixed sequence, exemplifies precision medicine applied to acute decongestive therapy.