Essential hypertension as a resistance rise

Resistance-driven hypertension is the Ohm identity run forward: raising systemic vascular resistance drives MAP up while MAP=CO×SVR holds to <1%. The same MAP (146 mmHg) is reachable from a pure cardiac-output rise at normal resistance — same pressure, different mechanism. Grade [F]; JNC7/ACC-AHA threshold [L].

Essential hypertension sets the resistance knob. Sweeping SVR upward carries MAP from 96 to 171 mmHg with the hydraulic Ohm law exact (max deviation 2e-06). A contrast run reaches the identical MAP by raising CO instead, separating resistance- from flow-driven hypertension at equal pressure.

Pressure up the resistance axis

The commonest hypertension is a rise in systemic vascular resistance at near-normal cardiac output. On the transport law MAP − CVP = CO×SVR this is simply the SVR term increasing; MAP follows linearly and the Ohm identity is preserved.

Same pressure, two mechanisms

Across the SVR sweep MAP rises 96→171 mmHg and crosses a stage-2 threshold (140/90) while the identity holds to 2e-06. The contrast makes the mechanism explicit: the resistance route (SVR 1.70, CO 83 mL/s) and a flow route (SVR 1.10, CO 129 mL/s) reach the same MAP 146 mmHg from opposite knobs. Pressure alone cannot distinguish them — the engine can, because it carries CO and SVR separately. This is the substrate for the hemodynamic sub-typing the next section completes for shock.