RESUMO
Thirteen patients with severe cardiac failure underwent a single crossover study of dopamine and dobutamine in order to compare the systemic and regional hemodynamic effects of the two drugs. The dose-response data demonstrated that dobutamine (2.5--10 microgram/kg/min) progressively and predictably increases cardiac output by increasing stroke volume, while simultaneously decreasing systemic and pulmonary vascular resistance and pulmonary capillary wedge pressure. There was no change in heart rate or premature ventricular contractions (PVCs)/min at this dose range. Dopamine (2--8 microgram/kg/min) increased the stroke volume and cardiac output at 4 microgram/kg/min. Dopamine at less than 4 microgram/kg/min provided little additional increase in cardiac output and increased the pulmonary wedge pressure and the number of PVCs/min. At greater than 6 microgram/kg/min, dopamine increased heart rate. During the 24-hour maintenance-dose infusion of each drug (dopamine 3.7--4, dobutamine 7.3--7.7 microgram/kg/min), only dobutamine maintained a significant increase of stroke volume, cardiac output, urine flow, urine sodium concentration, creatinine clearance and peripheral blood flow. Renal and hepatic blood flow were not signfiicantly altered by the maintenance dose of either drug. Systemic and regional hemodynamic data suggest that dobutamine has many advantages over dopamine when infused in patients with cardiac failure.
Assuntos
Catecolaminas/uso terapêutico , Dobutamina/uso terapêutico , Dopamina/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Hemodinâmica/efeitos dos fármacos , Adulto , Idoso , Pressão Sanguínea/efeitos dos fármacos , Débito Cardíaco/efeitos dos fármacos , Dobutamina/efeitos adversos , Dopamina/efeitos adversos , Dispneia/tratamento farmacológico , Humanos , Rim/fisiopatologia , Pulmão/fisiopatologia , Pessoa de Meia-Idade , Fluxo Sanguíneo RegionalRESUMO
A patient with primary cardiomyopathy and long standing atrial fibrillation presented with atrial tachycardia and AV block. Atrial pacing sequentially converted the atrial tachycardia to atrial flutter (biatrial) and to the dissimilar atrial rhythms of right atrial fibrillation with left atrial flutter, right atrial flutter with left atrial electrical standstill and right atrial fibrillation with left atrial standstill. The clincial milieu and intracardiac recordings are presented.