Hemodynamic, renal, and hormonal effects of rapid ventricular pacing in conscious dogs.

The interactions of the systemic adaptations during and after rapid ventricular pacing, a model of heart failure, were assessed in conscious, unstressed dogs. One week of ventricular tachycardia (260 beats/min) significantly reduced mean +/- SEM cardiac output (2.3 +/- 0.1 to 1.2 +/- 0.1 liter/min), mean arterial pressure (119 +/- 3 to 93 +/- 3 mm Hg), renal blood flow (168 +/- 19 to 96 +/- 9 ml/min), sodium excretion (36 +/- 5 to 10 +/- 4 mEq/d), increased left and right atrial pressures (8 +/- 1 to 21 +/- 1 and 4 +/- 0 to 11 +/- 1 mm Hg, respectively), plasma atrial natriuretic peptide concentration (24 +/- 4 to 141 +/- 38 fmol/ml), plasma cyclic GMP concentration (9 +/- 1 to 16 +/- 4 pmol/ml), and urinary cyclic GMP excretion (0.77 +/- 0.05 to 2.18 +/- 0.34 nmol/min). These changes persisted throughout 3 weeks of pacing. Gradual increases in systemic and renal vascular resistances (to 122 +/- 17 and 1.30 +/- 0.22 mm Hg/liter/min, respectively) and reductions in glomerular filtration rate (65 +/- 6 to 44 +/- 4 ml/min) reached significance during the third week. Resumption of sinus rhythm stimulated a brisk natriuresis and a return of cardiac output, systemic vascular resistance, and hormone concentrations to control values within 7 days. However, increases of left and right atrial pressures (14 +/- 2 and 8 +/- 1 mm Hg, respectively) were still present after 2 months of recovery. In conclusion, persistent increases in cardiac filling pressures were induced by rapid ventricular pacing in conscious, unstressed dogs, whereas the systemic hemodynamic, renal, and hormonal responses were largely reversible during recovery.(ABSTRACT TRUNCATED AT 250 WORDS)