Factors that contribute to resistant forms of hypertension. Pharmacological considerations

Individualizing antihypertensive combination therapies: clinical and hemodynamic considerations

While there are strong trial data to guide the selection of initial hypertension treatment choice and limited data to support second agent choice, beyond the first two agents, subsequent steps are empiric. As medications are added, the resulting polypharmacy may be complex, inefficient and poorly tolerated, resulting in low treatment adherence rates. The selection of antihypertensive drug therapy based on hemodynamic mechanisms is not new but became practical with the availability of noninvasive hemodynamic parameters using impedance cardiography. Individualized therapy based on hormonal or hemodynamic measurements can effectively control hypertension as shown in several small clinical trials. Hemodynamic measurements are obtained quickly, painlessly and can be used in a serial fashion to guide treatment adjustments. Current limitations relate to availability of the measurement device and personnel trained in its use, reimbursement for the measurements, expertise in interpretation of the measurements and systems to adjust medication and repeat measurements in a serial fashion until targets are attained. The potential utility of this approach increases with greater complexity of the medication regimen. Further studies are indicated and may advance options for individualized treatment of hypertensive patients.

Treatment of resistant hypertension

Although the true prevalence of resistant hypertension is not known, it is likely that this condition will become increasingly common, driven by an aging population, obesity, nonadherence trends, and effects of target-organ disease. Current approaches focus on two goals: evaluation and correction of contributing causes, then selection of an effective drug regimen. Lifestyle factors contribute to resistance, particularly high sodium intake and weight gain. Secondary causes should be considered and corrected if feasible. Recent efforts have focused on the development of clinical pathways to guide treatment, based on plasma renin activity, aldosterone production, or hemodynamic measurements. The components of drug combinations beyond the second agent remain empiric. Although volume expansion plays a key role in drug resistance, clinical assessment of volume status is often difficult, frustrating efforts to achieve blood pressure control. Determination of the most effective approaches will require clinical trials using combination therapy.