Effects of short-term administration of dobutamine on left ventricular performance, exercise capacity, norepinephrine levels, and lymphocyte adrenergic receptor density in congestive heart failure

Long-term Intermittent Dobutamine Infusion, Combined With Oral Amiodarone for End-Stage Heart Failure

STUDY OBJECTIVES

To examine the effects of long-term intermittent dobutamine infusion, combined with oral amiodarone in patients with congestive heart failure (CHF) refractory to standard medical treatment.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial.

SETTING

Inpatient and outpatient heart failure clinic in a university teaching hospital.

PATIENTS AND INTERVENTIONS

Thirty patients with end-stage CHF refractory to standard medical treatment who could be weaned from dobutamine therapy after a first 72-h infusion were randomized in a double-blind manner to receive IV infusions of placebo (group 1; 14 patients) vs dobutamine in a dose of 10 micro g/kg/min (group 2; 16 patients) for 8 h every 14 days. All patients received standard medical therapy and also were treated with oral amiodarone, 400 mg/d, which was started at least 2 weeks before randomization.

MEASUREMENTS AND RESULTS

Kaplan-Meier survival analysis showed a 60% reduction in the risk of death from any cause in the group treated with the combination of dobutamine and amiodarone, compared with the group treated with placebo and amiodarone (hazard ratio, 0.403; 95% confidence interval, 0.164 to 0.992; p = 0.048). The 1-year and 2-year survival rates were 69% and 44%, respectively, in the dobutamine-treated group, vs 28% and 21%, respectively, in the placebo-treated group (p < 0.05 for both comparisons). Median survival times were 574 and 144 days, respectively, for groups 2 and 1. At 6 months, the New York Heart Association functional class was significantly improved in the patients who survived from both groups.

CONCLUSIONS

Long-term intermittent dobutamine infusion combined with amiodarone added to the conventional drugs improved the survival of patients with advanced CHF that was refractory to conventional treatment.

Long-term intermittent dobutamine infusion combined with oral amiodarone improves the survival of patients with severe congestive heart failure

STUDY OBJECTIVE

To evaluate the effects of long-term intermittent dobutamine infusion (IDI) with concomitant administration of low-dose amiodarone in patients with congestive heart failure (CHF) refractory to standard medical treatment.

DESIGN

Prospective, interventional clinical trial.

SETTING

Inpatient and outpatient heart failure clinic in a university teaching hospital.

PATIENTS AND INTERVENTIONS

Twenty-two patients with CHF refractory to standard treatment who could be weaned from dobutamine therapy after an initial 72-h infusion were included in this study. The first 11 patients (group 1) were treated with IDI, 10 micromin, as needed (mean, once every 16 days, lasting for 12 to 48 h); the next 11 patients (group 2) received oral amiodarone, 400 mg/d, and IDI, 10 microg/kg/min, for 8 h every 7 days.

MEASUREMENT AND RESULTS

There were no differences in baseline clinical, hemodynamic, and five biochemical characteristics between the two groups. The left ventricular ejection fraction was 13.5 +/- 4.5% in group 1 vs 15.5 +/- 4.9% in group 2 (mean +/- SD; p = 0.451); mean pulmonary capillary wedge pressure was 31.3 +/- 4.4 mm Hg vs 29.4 +/- 3.3 mm Hg (p = 0.316); serum creatinine was 1.9 +/- 0.4 mg/dL vs 1.6 +/- 0.5 mg/dL (p = 0.19); and serum Na was 139.6 +/- 6.2 mEq/L vs 138.4 +/- 3.1 mEq/L (p = 0.569). At 12 months of follow-up, 1 of 11 patients (9%) was alive in group 1 vs 6 of 11 patients (55%) in group 2 (p = 0.011). Furthermore, in group 2, the functional status improved significantly within the first 3 months of treatment, from New York Heart Association functional class IV to 2.63 +/- 0.5 (p = 0.0001).

CONCLUSION

Long-term IDI in conjunction with amiodarone, added to conventional drugs, improved clinical status and survival of patients with severe CHF.

Pathophysiology of pediatric heart failure

Our understanding of the syndrome of heart failure has undergone several revisions, most importantly in the second half of the 20th century. New insights into the mechanisms of diseases offer new, challenging, controversial and sometimes counterintuitive forms of therapy. The development and progression of heart failure results from a complex interplay of hemodynamic and neurohormonal, cellular and genetic factors, rather than simply changes in cardiac function. It is because of this reason that our therapeutic focus can no longer be solely based on supply and demand models. Since the description of the pulsatile nature of the heart function and the flow of blood around a circuit by W. Harvey, numerous new paradigms have been put forward to explain the nature of heart failure. However, no single new model thus far proposed has been able to displace previous ones and successfully dictate therapy. It is the purpose of this manuscript to review the overall current understanding of the heart failure syndrome and how these new ideas may affect our therapeutic approach.

Intermittent dobutamine treatment in patients with chronic refractory congestive heart failure: a randomized, double-blind, placebo-controlled study

BACKGROUND

Intravenous dobutamine administration improves short-term hemodynamics in patients with severe congestive heart failure (CHF). However, the clinical benefit of periodic administration remains controversial.

OBJECTIVE

To evaluate the efficacy of intermittent dobutamine administration in patients with refractory CHF.

METHODS

Nineteen patients with New York Heart Association class III/IV, ischemia-induced CHF participated in this double-blind, placebo-controlled study. All patients received intravenous dobutamine or placebo over a 24-hour period every 2 to 3 weeks for 6 months. They were also treated with angiotensin-converting enzyme inhibitors, digoxin, and diuretics. The number of admissions for CHF and mortality rate were compared.

RESULTS

Ten patients received dobutamine and nine received placebo. The pretreatment characteristics were similar in both groups. No statistically significant difference was observed between the number of admissions for CHF (p = 0.11). The median survival after enrollment was 7.97 months in the placebo group and 4.6 months in the dobutamine group. The Kaplan-Meier survival curves overlay, with no statistically significant difference between the treatment arms (p = 0.7).

CONCLUSION

Intermittent dobutamine infusions in patients with refractory CHF have no effect on the need for hospitalization or on survival.

Effects of continuous positive airway pressure on cardiac output and plasma norepinephrine in sedated pigs

Continuous positive airway pressure (CPAP) increases cardiac output (CO) in congestive heart failure (CHF). In six sedated pigs that were normovolemic (NV) and hypervolemic (HV), and seven previously instrumented pigs with pacing-induced CHF, we tested the hypothesis that this is associated with decreased total body sympathetic nerve activity (SNA). Hemodynamic variables and plasma norepinephrine level measurements were measured at baseline, CPAP 5 and 10 cm H2O, and recovery. Arterial O2 saturation was maintained at greater than or equal to 90% and PCO2 did not change. For NV baseline plasma norepinephrine level (PNE) was 97 +/- 61 pg/mL, CO 2.4 +/- .5 L/min, and pulmonary wedge pressure (Pw) 10.1 +/- 2.4 mmHg and did not change with CPAP. HV and CHF were associated with increased baseline Pw (18-21 mmHg). Baseline CO was increased with HV and unchanged with CHF. Baseline PNE was increased 4 to 5-fold with both HV and CHF. CO increased at CPAP 5 compared with baseline with both HV and CHF. However, PNE decreased with CPAP in HV, and increased with CPAP in CHF. Increased CO was always associated with decreased systemic vascular resistance. We conclude the following: (1) increased CO with CPAP can be associated with either increasing or decreasing SNA; (2) CPAP can produce increases in CO when the heart is distended whether baseline LV function is relatively normal (HV) or depressed (CHF); and (3) there are probably a number of different mechanism increasing CO with CPAP and these may vary from condition to condition.