The hemodynamic actions of prenalterol in left ventricular failure

The hemodynamic effects of prenalterol, a parenteral cardioselective beta 1-receptor agonist, were evaluated by cardiac catheterization in patients with refractory severe congestive heart failure (CHF). Prenalterol (PN) (4 mg i.v.) did not alter (p greater than 0.05) heart rate (HR), mean blood pressure (MBP) or left ventricular filling pressure (LVFP). Concomitantly PN markedly augmented cardiac index (CI) from 1.9 to 2.6 l/min/m2 (p less than 0.01) and substantially elevated stroke index (SI) from 24 to 30 ml/beta/m2 (p less than 0.001). In addition PN raised stroke work index (SWI) from 21 to 26 g . m/m2 (p less than 0.005) and decreased total systemic vascular resistance (TSVR) from 1702 to 1260 dyn . s. cm-5 (p less than 0.001). An important finding was that the heart rate x systolic blood pressure product was unchanged (p greater than 0.05) and precipitation of cardiac dysrhythmias or myocardial ischemia were not observed. Further PN 1 mg, 4 mg and 8 mg i.v. was sequentially injected and peak hemodynamic effects were determined 10 min after drug administration. PN 1 mg raised CI from 2.1 to 2.5 1/min/m2 (p less than 0.01), elevated SI from 24 to 29 ml/beat/m2 (p less than 0.01), and augmented SWI from 21 to 25 g . m/m2 (p less than 0.01), however, TSVR declined from 1702 to 1392 dyn . s. cm-5. Subsequent incremental PN doses of 4 and 8 mg did not provide (p greater than 0.05) additional enhancement of cardiac function. Thus, prenalterol produced markedly beneficial enhancement of cardiocirculatory function without untoward effects and may be useful in the management of patients with severe congestive heart failure. Moreover, dose-response analysis indicates these salutary improvements can be maximally produced by the small dose of 1 mg obviating the need for larger doses.