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2.
Am J Physiol ; 271(4 Pt 2): H1635-42, 1996 Oct.
Article in English | MEDLINE | ID: mdl-8897961

ABSTRACT

Positive inotropic intervention with dobutamine in patients with congestive heart failure is accompanied by complementary vascular changes, as measured by the aortic input impedance spectrum, that promote the efficient transfer of augmented myocardial contractile power. It is unknown whether this is a nonspecific response to increased ventricular contractility or is a function of the properties of the positive inotropic agent employed. Therefore, the influence of two different positive inotropic interventions, dobutamine and dopamine, on ventricular-vascular coupling was examined in 15 patients with congestive heart failure. Significant reductions in characteristic aortic impedance, wave reflection, and low-frequency impedance moduli were noted with dobutamine and were not seen with dopamine. Consequently, a significantly (P = 0.0008) greater increase in pulsatile, rather than steady-state, power output was noted with dopamine that was reflective of a significantly diminished efficiency of power transfer. Therefore, optimal transfer of increased ventricular contractile power in patients with congestive heart failure requires increases in large vessel compliance and complementary changes in ventriculoarterial coupling.


Subject(s)
Cardiomyopathy, Dilated/drug therapy , Cardiotonic Agents/therapeutic use , Dobutamine/therapeutic use , Dopamine/therapeutic use , Myocardial Contraction , Ventricular Function , Aged , Aorta/physiopathology , Cardiomyopathy, Dilated/physiopathology , Female , Hemodynamics , Homeostasis , Humans , Male , Middle Aged , Vascular Resistance , Ventricular Function/drug effects
3.
Am J Cardiol ; 72(11): 770-5, 1993 Oct 01.
Article in English | MEDLINE | ID: mdl-8213508

ABSTRACT

Contrast agents used for cardiac angiography are different in regard to ionicity, osmolality and physiologic effects. The nonionic contrast media have been shown to have less toxic effects and a better safety profile than do higher osmolar agents. To better assess this risk, clinically stable patients undergoing cardiac angiography were stratified according to the presence of diabetes mellitus, and level of serum creatinine, and then randomized to receive either iohexol (Omnipaque 350) or sodium meglumine diatrizoate (Renografin 76). All adverse events that occurred during and immediately after angiography were tabulated. A multivariate model was used to identify patients at increased risk for adverse outcome. The 1,390 patients were randomized to iohexol (n = 696) or diatrizoate (n = 694). Significant differences were found in the number of patients with contrast media-related adverse (iohexol vs diatrizoate: 10.2 vs 31.6%; p < 0.001) and cardiac adverse (7.2 vs 24.5%; p < 0.001) events. Severe reactions and the need for treatment were more frequent with diatrizoate than with iohexol, but there was no difference in the incidence of death. The presence of New York Heart Association classification 3 or 4 and serum creatinine > or = 1.5 mg/dl predicted a higher incidence of adverse events as a result of contrast media alone. Use of iohexol is associated with a lower incidence of all types of adverse events during cardiac angiography than is diatrizoate.


Subject(s)
Angiocardiography , Contrast Media/adverse effects , Diatrizoate Meglumine/adverse effects , Diatrizoate/adverse effects , Heart Diseases/diagnostic imaging , Iohexol/adverse effects , Adult , Aged , Aged, 80 and over , Cardiovascular Diseases/chemically induced , Creatinine/blood , Diabetes Complications , Drug Combinations , Female , Heart Diseases/blood , Heart Diseases/complications , Humans , Logistic Models , Male , Middle Aged
6.
J Am Coll Cardiol ; 15(5): 1127-35, 1990 Apr.
Article in English | MEDLINE | ID: mdl-2312969

ABSTRACT

The aortic input impedance spectrum provides a description of the total hydraulic load imposed on the left ventricle and may be used to assess the coupling of the ventricle to the vasculature. The adaptation of the vasculature to positive inotropic intervention was examined in 10 patients with idiopathic dilated cardiomyopathy to test the hypothesis that increased myocardial contractility is matched by complementary changes in aortic impedance that optimize ventricular-vascular coupling and maximize power transfer to the circulation. High fidelity intravascular recordings of aortic pressure and flow were obtained at baseline study and during infusion of dobutamine to derive the aortic input impedance spectrum. In eight patients in whom increased staged infusion of dobutamine resulted in a significant increase in stroke volume (22.3 +/- 14.5 ml/beat increase over baseline), the significant (p less than 0.05) increase in the maximum of the first derivative left ventricular pressure pulse (dP/dt) was accompanied by significant decreases in characteristic impedance of the aorta (138 +/- 88 to 92 +/- 44 dyne.s.cm-5) wave reflection index (238 +/- 144 to 109 +/- 59 dyne.s.cm-5), and low frequency moduli of impedance. Effective positive inotropic therapy with dobutamine in the setting of congestive heart failure is accompanied by complementary changes in the aortic impedance spectrum, which represent a matching of impedance to the increased contractile state of the ventricle and facilitation of ventricular-vascular coupling.


Subject(s)
Aorta/drug effects , Cardiomyopathy, Dilated/drug therapy , Dobutamine/therapeutic use , Myocardial Contraction/drug effects , Adult , Aged , Blood Flow Velocity/drug effects , Cardiomyopathy, Dilated/physiopathology , Female , Hemodynamics/drug effects , Humans , Male , Middle Aged , Pulsatile Flow/drug effects , Stroke Volume/drug effects
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