Effect of continuous arteriovenous haemofiltration on pharmacokinetics of amrinone

This case report details the pharmacokinetic adjustments of an amrinone infusion in a paediatric patient who developed multiorgan system failure with anuric renal failure and was prescribed continuous arteriovenous haemofiltration. A significant proportion of clearance of amrinone is nonrenal. Near normal amrinone clearance can occur in patients with hepatic and renal dysfunction if continuous arteriovenous haemofiltration is used. Hepatic dysfunction with renal failure may require a reduction in the continuous amrinone infusion rate as previously reported for neonates.

Selective pulmonary and systemic vasodilator effects of amrinone in children: new therapeutic implications

OBJECTIVES

The present study was performed to determine the systemic and pulmonary hemodynamic effects of amrinone in infants and children with a cardiac left to right shunt to determine if there is a beneficial effect on the pathophysiology of this condition.

BACKGROUND

Amrinone is a bipyridine derivative with inotropic and vasodilator effects that have not been systematically evaluated in the pediatric patient with increased pulmonary blood flow.

METHODS

Nineteen patients (aged 2 months to 8.3 years) with one or more left to right shunts were evaluated during cardiac catheterization with direct hemodynamic measurements made before and 10 min (peak effect) after administration of a bolus injection of amrinone, 3 mg/kg body weight. The Fick method was used to calculate pulmonary and systemic blood flow, and resistances were then calculated.

RESULTS

In group A, five patients with normal pulmonary artery pressure and resistance, amrinone significantly reduced mean pulmonary artery pressure by 19%, mean left atrial pressure by 39% and systemic vascular resistance by 17%. In group B, seven patients with pulmonary artery hypertension (mean pulmonary artery pressure > 20 mm Hg) and normal pulmonary vascular resistance (total pulmonary resistance < or = 3 Wood U.m2), amrinone significantly reduced the pulmonary artery pressure by 27%, systolic aortic pressure by 5%, mean aortic pressure by 12%, pulmonary arteriolar resistance by 36% and total pulmonary vascular resistance by 26%. In group C, seven patients with pulmonary artery hypertension (mean pulmonary artery pressure > 20 mm Hg) and elevated pulmonary vascular resistance (total pulmonary resistance > 3 Wood U.m2), amrinone significantly reduced the pulmonary arteriolar resistance by 49%, total pulmonary resistance by 47% and pulmonary arteriolar/systemic vascular resistance ratio by 45% and increased the heart rate by 15%.

CONCLUSIONS

In children with a cardiac left to right shunt, amrinone 1) appears to have selective vasodilator effects depending on the pulmonary artery pressure and resistance, 2) has a beneficial hemodynamic effect in children with normal pulmonary artery pressure and resistance, and 3) may have a role in the treatment of patients with pulmonary artery hypertension without causing systemic hypotension.

[Tendency of development on novel type of cardiotonic drugs]

The narrow margin of safety of cardiotonic glycosides has led to extensive studies for novel cardiotonic agents that are superior to the glycosides. Cardiotonic drugs acting on beta-adrenoceptors and inhibitors of cAMP phosphodiesterase have been extensively studied and used for the treatment of heart failure. Ca sensitizers are of interest, since such a mechanism of action may be beneficial for the failing heart. Recently, cardiotonic substances with a novel mechanism of action such as gingerol and xestoquinone have been isolated from natural sources. Furthermore, 9-methyl-7-bromoeudistomin D, a powerful radiolabeled Ca2+ releaser having caffeine-like properties, may provide a promising tool for studying the molecular mechanism of the Ca2+ release process.

Inotropic therapy in the critically ill patient

Inotropic support is an important therapeutic modality in the intensive care unit. There are three classes of agents available to the clinician: catecholamines, bipyridines, and cardiac glycosides. Each class increases inotropy by a different mechanism and each agent has distinct physiological and pharmacological actions. It is important to understand the underlying pathophysiology involved so the appropriate inotrope can be chosen on a rational basis. Prior to and during therapy invasive hemodynamic monitoring is required to ensure proper titration of the chosen agent. If an undesirable effect ensues, therapy can then be modified.

Low-output syndrome after heart surgery: is a monotherapy with phosphodiesterase-III inhibitors feasible? A comparative study of amrinone and enoximone

In order to determine whether the primary use of a phosphodiesterase-III (PDE) inhibitor as monotherapy for severe cardiac low-output states (LOS) is in fact practicable, we investigated the haemodynamic effects of amrinone and enoximone in a prospective randomized study. After elective CABG, AVR, or MVR, patients with cardiac LOS were given amrinone (n = 10) or enoximone (n = 9). Following bolus saturation (1.0-2.0 mg/kg [XA = 1.4] or 0.5-1 mg/kg [XE = 0.9] in total), a dose of 5-10 microgram/kg/min was given by infusion. The standard monitoring program included discontinuous haemodynamic measurements (Swan-Ganz) over a maximum time period of 48 hours, arterial and venous blood-gas analyses, and clinical chemistry. The preoperative clinical and haemodynamic status of the enoximone (E) group (55% CABG patients; MPAP 27 +/- 2.5 mmHg, PCWP 20 +/- 2.9 mmHg, PVR 201 +/- 35 dyn.s.cm-5) was considerably worse than that of the amrinone (A) group (70% CABG patients; MPAP 23 +/- 2.3 mmHg, PCWP 16 +/- 3.5 mmHg, PVR 153 +/- 28 dyn.s.cm-5). Both PDE inhibitor preparations led to a significant increase in cardiac index (from 1.9 +/- 0.1 to 2.5 +/- 0.12 L/min/m2 (A) and from 1.98 +/- 0.1 to 2.6 +/- 0.18 L/min/m2 (E) within 30 minutes, accompanied by a simultaneous decrease in filling pressures and vascular resistances. For up to 2 hours, 3/10 (A) and 2/9 (E) patients required additional positive inotropic support with adrenaline. There were no significant differences between the two groups at any time.(ABSTRACT TRUNCATED AT 250 WORDS)

Amrinone and dobutamine as primary treatment of low cardiac output syndrome following coronary artery surgery: a comparison of their effects on hemodynamics and outcome

This study was undertaken in order to compare the effectiveness of amrinone and dobutamine as primary treatment of a low cardiac output (CO) after coronary artery bypass graft (CABG) surgery. Thirty patients with preoperative left ventricular dysfunction participated in this open-label randomized study. Patients were included if they failed to separate from cardiopulmonary bypass (CPB) without inotropic support or if they had a cardiac index (CI) less than 2.4 L/min/m2 after CPB regardless of the blood pressure, in the presence of adequate filling pressures. The treatment objectives were to separate from CPB and achieve a CI > or = 2.4 L/min/m2 and a mean arterial pressure > or = 70 mmHg. Patients treated with amrinone received 0.75 mg/kg followed by 10 micrograms/kg/min; when the objectives were not achieved within five minutes, another 0.75 mg/kg was given. Patients treated with dobutamine received an initial infusion of 5 micrograms/kg/min increased stepwise to 15 micrograms/kg/min if necessary. Eleven of 15 amrinone versus 6 of 15 dobutamine patients achieved the predefined treatment objectives with the test drug alone (P = NS). Comparisons of hemodynamics in patients treated solely with amrinone (n = 7) or dobutamine (n = 6) after CPB showed no significant differences between the treatment groups. The incidence of myocardial ischemia as detected by Holter monitor was 36% with amrinone and 33% with dobutamine. Two patients suffered ventricular fibrillation and two had significant supraventricular tachyarrhythmias (heart rate > 130/min) during treatment with dobutamine alone, whereas no significant arrhythmias occurred in the amrinone group (P = NS). Six dobutamine patients (40%) had postoperative myocardial infarction (MI) as opposed to none among the amrinone patients (P = 0.017). These results indicate that amrinone compares favorably with dobutamine as a primary treatment of low CO after CABG. Further study in a larger number of patients will be required in order to determine if the lower incidence of MI in the amrinone group was due to the treatment drug.

[Hemodynamic effects of amrinone on cardiopulmonary decompensated chronic cor pulmonale]

Amrinone was given intravenously combined with the routine treatment to 10 patients with late chronic cor pulmonale in exacerbation stage. The initial loading dose was 1.5-2 mg/kg followed by the maintenance dose of 15 micrograms/kg. min for 6 hours. Hemodynamic and blood gas monitoring showed that pulmonary artery pressure, pulmonary vascular resistance index, right atrial pressure and pulmonary capillary wedge pressure decreased significantly and maintained the level markedly below baseline after amrinone administration (the extents decreased were 0.53-1.1 kPa, 80-140 dyn.s.m2.cm-5, 0.27-0.40 kPa and 0.40-0.67 kPa respectively. P < 0.05 for each parameter) and that cardiac index and stroke volume index increased identically (the extents increased were 0.3-0.6 L/min.m2 and 2-4 ml/beat.m2 respectively, P < 0.05 for each parameter). There were no significant changes in systemic artery pressure, arterial blood gas analysis and blood platelet count after amrinone administration. We suggest that amrinone may be effective in the treatment of cardio-pulmonary decompensated chronic cor pulmonale.

The effect of amrinone on recovery from severe bupivacaine intoxication in pigs

Cardiovascular collapse following intravascular bupivacaine may be resistant to treatment. The effect of amrinone on recovery from bupivacaine-induced severe cardiovascular depression was evaluated in 20 pigs (13-26 kg) in a placebo-controlled randomized double-blind study. Under 0.7% isoflurane anesthesia at FIO2 0.21, 0.5% bupivacaine 2 mg.kg-1.min-1 was infused until mean arterial pressure was 40% of the baseline. Cardiac output and heart rate decreased 75% and 50% from the baseline, respectively. The total dose of bupivacaine was 17 +/- 6 (SD) mg.kg-1 in the control and 19 +/- 5 mg.kg-1 in the amrinone group, resulting in mean plasma concentrations of 42 +/- 6 and 53 +/- 19 micrograms.ml-1, respectively. A bolus of amrinone 4 mg.kg-1 (n = 10) was given immediately after cardiovascular depression, followed by an infusion of 0.6 mg.kg-1.min-1. The control animals received corresponding volumes of physiologic saline (n = 10). After cardiovascular depression, the lungs were ventilated with FIO2 1.0 without anaesthetics or sympathomimetic support. Electric activity of the heart ceased in all control animals in 3.9 +/- 2 min after cardiovascular depression despite atropine and external cardiac compression. All animals in the control group and 5 of 10 animals in the amrinone group were given atropine (P less than 0.01). The animals receiving amrinone survived without cardiac compression (P less than 0.0001). During bupivacaine infusion, all animals developed burst suppression in the electroencephalogram. At the time of cardiovascular depression, in 8 of 10 control and in 6 of 10 amrinone animals, the electroencephalogram was isoelectric.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of amrinone in a canine model of massive pulmonary embolism

Amrinone, an inotrope with vasodilating properties, is of potential use in managing the right ventricular failure and pulmonary vasoconstriction induced by massive pulmonary embolism (PE). Therefore, to determine the hemodynamic effects of amrinone in a canine model of massive PE, autologous blood clot was infused into ten dogs (eight treated and two control animals) in an amount sufficient to decrease mean systemic arterial pressure (MAP) by at least 25 percent. This resulted in an increase in mean pulmonary artery pressure (MPAP) from 13.4 +/- 3.7 mm Hg to 44.4 +/- 4.8 mm Hg (p less than 0.01), a decrease in MAP from 122 +/- 9.5 mm Hg to 35.6 +/- 9.8 mm Hg (p less than 0.01), and a decrease in cardiac output from 2.73 +/- 0.834 L/min to 1.22 +/- 0.61 L/min (p less than 0.01). Amrinone was administered in an initial bolus of 0.75 mg/kg followed by an infusion of 7.5 micrograms/kg/min, which resulted in significant hemodynamic improvement in all subjects, with a fall in MPAP to 35.3 +/- 5.1 mm Hg (p less than 0.01), an increase in MAP to 98.1 +/- 31.1 mm Hg (p less than 0.01), and an increase in cardiac output to 2.01 +/- 0.7 L/min (not significant) at 5 min. Cardiac output continued to increase to 2.56 +/- 0.16 L/min (p less than 0.01) at 35 min. We conclude that amrinone alleviated pulmonary hypertension, systemic hypotension, and low cardiac output in a canine model of massive PE.

[Amrinone for cardiovascular therapy in hypodynamic septic patients?]

Pulmonary hypertension, systemic vasodilation and the supply dependency of oxygen uptake are the major problems associated with sepsis. Thus, the goal of haemodynamic therapy in septic patients is an increase in cardiac output large enough to permit adequate tissue oxygenation. The purpose of this study was to establish whether the additional use of the phosphodiesterase inhibitor amrinone is useful in hypodynamic septic patients with inadequate tissue perfusion. Nine patients who had developed the clinical signs of sepsis (temperature greater than 38.5 degrees C, leukocytosis greater than 15,000/mm3, thrombopenia less than 100,000/mm3 or a drop in platelet count greater than 30%, cardiovascular shock) were given amrinone 30 micrograms.kg-1.min-1 for one hour. All patients showed mixed venous oxygen saturations below 70% and oxygen extraction rates above 30%, despite maximum catecholamine therapy. Haemodynamic parameters were measured with the help of a pulmonary artery catheter. Statistical significance was checked using the Wilcoxon signed-ranks test. During amrinone application cardiac index increased significantly from 4.6.1.81.min-1.m-2 to 5.6 +/- 1.81.min-1.m-2 (p less than 0.01), while central venous pressure was kept constant by volume supply. Mean pulmonary artery pressure remained nearly unchanged, whereas mean arterial pressure dropped significantly from 91 +/- 13 mmHg to 75 +/- 8 mmHg (p less than 0.01). The oxygen supply rose during administration of amrinone by an average of 17%, which led to a rise in oxygen uptake. Independence of oxygen uptake from oxygen supply, however, could not be attained. In septic patients, amrinone increases cardiac output via pulmonary vasodilation. However, pronounced systemic vasodilation lowers arterial blood pressure, enhancing the risk of myocardial ischaemia.

[Efficacy and safety of amrinone in the treatment of heart insufficiency in intensive care]

The authors describe the results obtained treating with amrinone for 48 hours 11 patients with acute heart failure. The patients (4 males and 7 females), age range between 50 and 82 years) received an initial bolus of 0.75 mg/kg followed by and infusion which on average was of 5.82 +/- 1.06 (SD) micrograms/kg/min. Besides a subjective and objective clinical improvement they could observe a quick and remarkable improvement of the main hemodynamic parameters (cardiac index, cardiac output, pulmonary capillary wedge pressure, mean pulmonary pressure). The tolerability of the drug was good, except for a decrease in platelet, already described in literature. In conclusion, the Authors consider amrinone a very interesting drug for its positive inotropic and vasodilating activity and because it does not cause an increase of the myocardial oxygen consumption.

Amrinone before termination of cardiopulmonary bypass: haemodynamic variables and oxygen utilization in the postbypass period

One hundred patients were randomly allocated to receive saline or amrinone, 0.75 mg.kg-1, ten minutes before separation from cardiopulmonary bypass (CPB) after elective coronary artery bypass grafting, in order to determine the effects of this agent on haemodynamic variables and O2 utilization. Anaesthesia and CPB were managed in a standard fashion. Before induction of anaesthesia, at pericardiotomy, then at 1, 10, 20 and 30 min after CPB, haemodynamic profiles, haematocrit, and O2 saturation of arterial and mixed venous blood were measured. Incremental doses of ephedrine or phenylephrine, or an infusion of norepinephrine with phentolamine were administered when required. The groups were demographically similar and surgical variables were also similar. Haemodynamic measurements were similar between groups at all times; however, a higher dose of phenylephrine was given immediately before weaning from CPB in the amrinone group, and more patients in this group received phenylephrine in the first 30 min after CPB. Mixed venous saturation (SvO2) was higher in the amrinone patients at all times after CPB, leading to lower calculated oxygen consumption (VO2) (P less than 0.05). Insufficient dosage may explain the lack of haemodynamic effect, while possible reasons for the higher SvO2 and lower VO2 are either reduced whole body VO2 or peripheral shunting.

Amrinone as an inotrope in managing hypermetabolic surgical stress

Dobutamine is the standard inotrope used as cardiac support for hyperdynamic hypermetabolic patients following acute surgical stress. Amrinone has been utilized in medical patients with heart failure, but its use in hyperdynamic patients to our knowledge has never been reported. We now report the results of a trial of amrinone versus dobutamine in this setting. Over a 3-month period, we compared 28 trials of dobutamine and 27 trials of amrinone in 47 patients. Attempts were made to achieve non-flow-dependent oxygen consumption. Values are expressed as pre/post inotrope. Student's two-tailed t test was used for evaluation. [table: see text] Patients treated initially with dobutamine were slightly younger (mean, 46 vs. 57 years). They required slightly higher doses of dobutamine (mean, 12.9 vs. 12.2 micrograms/kg/min) and a slightly longer treatment period (mean, 11.3 vs. 9.8 hours) to achieve the desired effect. Of the 47 trials with dobutamine, six (13%) failed to achieve non-flow-dependent oxygen consumption. All then responded somewhat to amrinone. The failure rate for amrinone was 10%. No patient developed hypotension when treated with either drug. Amrinone is an effective inotrope useful in the cardiovascular support of hyperdynamic patients following surgical stress. Hypotension is not a problem with adequate intravascular volume loading. It should become part of the standard drug regimen in the surgical ICU.

Modulation of inotropic therapy by venodilation in acute heart failure: a randomised comparison of four inotropic agents, alone and combined with isosorbide dinitrate

The effects of four inotropic agents with differing ancillary properties [a cardiac glycoside (digoxin), a combined alpha- and beta-adrenergic agonist (dobutamine), a beta-adrenergic agonist (prenalterol), and a phosphodiesterase inhibitor (amrinone)] alone and with subsequent addition of isosorbide dinitrate were compared in 48 consecutive acute myocardial infarction patients with radiographic and haemodynamic (pulmonary artery occluded pressure greater than 18 mm Hg) left ventricular failure. All agents with the exception of dobutamine reduced the elevated left heart filling pressure; only digoxin and dobutamine augmented the cardiac stroke volume index. All drugs except digoxin reduced the SVRI; an arteriolar constrictor response was evident 60 min after digoxin and a tachycardia resulted after combined alpha- and beta- and beta-adrenergic stimulations (dobutamine and prenalterol, respectively). The addition of isosorbide dinitrate reversed the inotrope-induced elevations of systemic arterial pressure and resulted in additional reductions in left heart filling pressure. These data suggest that, in the absence of substantial venodilator properties in an inotropic compound, reduction in elevated left heart filling pressure is not achieved with inotropic therapy alone in acute left ventricular failure and combining a venodilator may be haemodynamically advantageous.

A comparison of amrinone and glucagon therapy for cardiovascular depression associated with propranolol toxicity in a canine model

This study's objective is to evaluate the ability of glucagon and amrinone to reverse propranolol induced cardiovascular depression in a canine model, compared to a control of normal saline. The study design included 18 animals which received intravenous propranolol (10 mg/kg) resulting in significant depression in heart rate, cardiac output, mean arterial pressure, maximal ventricular dP/dt and stroke volume. Each canine was randomly assigned to one of three treatment groups; controls (normal saline only), glucagon (20 micrograms/kg bolus) and amrinone (4 mg/kg bolus). Cardiovascular parameters were monitored at 1, 6, 11, 21 and 31 min after treatment was rendered. Multiple comparison procedures at each time period controlled the overall alpha-level at .05. Compared to control animals, both amrinone and glucagon were effective in reversing propranolol-induced depression of dP/dtmax at 6 and 11 min for glucagon and 11 min for amrinone and cardiac output at 1, 6 and 11 min for glucagon and 1 min for amrinone. Amrinone and glucagon significantly increased stroke volume over control values at 1 min and tended to do so at the remaining time periods. The two days caused a similar degree of arteriolar vasodilation which was significantly greater than that seen in control animals at 1 and 6 min. Beta blocker induced bradycardia did not respond significantly to amrinone while glucagon induced a tachycardia which is unique to canines. It is concluded that in this canine model, amrinone appears to be an effective therapeutic alternative to glucagon for reversing depressed dP/dtmax, cardiac output and stoke volume induced by propranolol toxicity. Unlike glucagon, amrinone appears to lack positive chronotropic activity which may limit its clinical utility in the treatment of beta blocker overdose.

[Mixed venous oxygen saturation as optimization of the therapeutic response in low output syndrome]

The Authors report on their experience about SvO2 continuous monitoring in order to find out the best therapeutic answer to inotropic drugs, knowing that, at constant values of SaO2 and Hb, possible variations of SvO2 reliably correspond with parallel variations of cardiac index (IC). Two groups of 15 patients each, suffering from low out-put syndrome, have been studied; patients have been treated with inotropic therapy based on Dobutamina and Amrinone. The 2 groups only differed from each other for the kind of monitoring: the first group was exposed to intermittent measurements of the cardiac out-put, while the second group was exposed to continuous monitoring of SvO2. Analysing the obtained results, the Authors notice not only a close correlation between the improvement of SvO2 and IC, but also a significant rediction in time required to dose drugs, owing to the constant help provided by on-line monitoring of SvO2. (table; see text)

[The treatment of heart insufficiency in coronary heart disease]

In acute as well as in chronic ischemic heart disease, congestive heart failure indicates a poor prognosis. Treatment after acute myocardial infarction should differentiate between specific subsets. In cardiogenic shock due to extensive ischemic damage, acute revascularization by PTCA or CABG improves the otherwise poor outcome substantially. In congestive heart failure, pre- and afterload reduction by nitrates should be combined with dopamine if systolic blood pressure is below 100 mmHG or dobutamine if an inotropic substance is necessary despite systolic blood pressure greater than 100 mmHg. Amrinone is a potent alternative which combines positive inotropic and vasodilating properties. In chronic ischemic heart disease, congestive heart failure is a clearly defined indication for complete revascularization, if possible. As to drug treatment, progression of the disease characterized by a cardiomyopathy of overload as well as neurohormonal and peripheral maladaptation should be stopped in parallel with symptom relief. Therefore, ACE-Inhibitors are combined very early with diuretic treatment, and digitalis should be added in refractory patients.

Amrinone for refractory cardiogenic shock following chloroquine poisoning

Cardiac arrhythmias and circulatory collapse account for the high mortality reported after severe chloroquine poisoning. We have recently observed a 17-year-old man who ingested an 8 g chloroquine overdose. Cardiac arrest occurred within 1 h. Cardiogenic shock was refractory to epinephrine, dopamine and molar sodium lactate. Amrinone, a bipyridine analog, was then successfully used to improve haemodynamic conditions.

Acute positive inotropic intervention: the phosphodiesterase inhibitors

Phosphodiesterase inhibitors that are selective for cAMP-specific cardiac and vascular PDE III comprise a new group of agents for the treatment of heart failure, which at present are limited to clinical shortterm intravenous use and research uses only. Although both intravenous amrinone and milrinone are FDA approved, only amrinone is available for general clinical use. Selective phosphodiesterase inhibition produces beneficial actions of positive inotropy and peripheral vasodilation that result from increased cardiac and vascular muscle concentrations of intracellular cAMP and ionic calcium. In addition, a positive lusitropic action (enhancement of cardiac relaxation) has been observed. Neither beta-adrenergic agonist activity nor inhibition of the sodium-potassium ATPase is produced by these agents. The magnitude of hemodynamic improvement generally exceeds that of the cardiac glycosides and is comparable with that of intravenous catecholamines such as dobutamine. The different pharmacodynamic profile of the PDE inhibitors is additive to the effects of cardiac glycosides, complementary and synergistic to the actions of catecholamines, and has been shown to have favorable effects on coronary hemodynamics. As a result there is continued enthusiasm for the short-term intravenous use of amrinone and potentially milrinone in the setting of acute heart failure resulting from systolic dysfunction (after myocardial infarction, open heart surgery, or infectious or toxic myocarditis), heart failure resulting from right ventricular systolic dysfunction, and when patients with severe heart failure await cardiac transplantation. Initiation of treatment with an intravenous bolus followed by a maintenance infusion provides prompt increases in stroke volume and cardiac output and simultaneous reductions in right and left ventricular filling pressures and systemic vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)