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 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of Amrinone on cardiac function soon after extracorporeal circulation (ECC) were studied in 5 patients including mitral valvuloplasty, VSD closure, Fontan operation and coronary AV fistel closure. In all patients, left ventricular volume load decreased postoperatively. To evaluate the efficacy, we obtained left ventricular pressure-volume loops (P-V loop) before and after ECC and after intravenous administration of Amrinone (1 mg/kg) following ECC. P-V loops were produced by measuring left ventricular pressure using a Miller catheter which was retrogradely advanced from the ascending aorta into the left ventricle and by measuring left ventricular diameter to calculate left ventricular volume with Teichholtz' formula. Although no apparent difference of Emax was recognized before and after ECC, Emax increased from 3.2 +/- 2.5 mmHg/cm3 to 5.9 +/- 4.7 mmHg/cm3 after the administration of Amrinone. The left ventricular "systolic" pressure-volume area (PVA) which is the sum of stroke work (SW) and elastic potential energy decreased from 34.4 +/- 16.4 gm to 30.9 +/- 17.8 gm after Amrinone. No difference was also recognized in left ventricular end-diastolic pressure. Ejection fraction increased from 50 +/- 17.5% to 56.1 +/- 17.3%. These results suggested that Amrinone could improve the left ventricular function without prominent change in myocardial oxygen consumption immediately after open heart surgery.
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PMID:[Effects of amrinone on left ventricular function following open heart surgery--analysis with left ventricular pressure volume loops]. 779 1

Amrinone, a phosphodiesterase inhibitor, and epinephrine, an alpha- and beta-adrenergic receptor agonist, are inotropic drugs used during cardiac surgery to reverse myocardial depression after cardiopulmonary bypass. However, these drugs have not been compared separately, or in combination, in this patient population. We hypothesized that the combination might have complementary actions in improving myocardial function. We, therefore, compared amrinone, epinephrine, and the combination of amrinone and epinephrine in a randomized, blinded, placebo-controlled study in patients undergoing coronary artery bypass grafting. Forty patients with ejection fractions > 0.45 were studied. Right ventricular ejection fraction pulmonary artery catheters and radial arterial catheters were inserted before fentanyl-midazolam anesthesia. After separation from bypass, patients received either a placebo (n = 20) or amrinone bolus (1.5 mg/kg, n = 20) at time 0 and a placebo (n = 20) or epinephrine (30 ng.kg-1.min-1, n = 20) infusion at time 5 min. This resulted in four study groups, n = 10 in each group. Data were collected every 2.5 min for 10 min. Epinephrine, amrinone, and the combination of both drugs significantly increased cardiac output, stroke volume, O2 delivery, and left ventricular stroke work. The increase in stroke volume (P < 0.05) was 12 +/- 6, 16 +/- 4, and 30 +/- 4 mL/beat with epinephrine, amrinone, and the combination of amrinone and epinephrine, respectively. The amrinone-epinephrine combination increased stroke volume as much as the sum of amrinone and epinephrine given separately. Systemic vascular resistance and pulmonary vascular resistance decreased with amrinone and amrinone-epinephrine, but not with epinephrine. Epinephrine increased mean arterial and mean pulmonary arterial pressures. Right ventricular ejection fraction did not significantly increase (P = 0.09) with epinephrine, but increased significantly with amrinone (0.45 to 0.53, P = 0.01), and with the combination (0.43 to 0.55, P = 0.006). These data indicate that amrinone and epinephrine effectively increase myocardial performance during cardiac surgery. Right ventricular function especially was improved with amrinone and the combination of amrinone and epinephrine. The combined effects of amrinone and epinephrine may be useful in patients recovering from the ischemia and reperfusion injury resulting from coronary artery bypass grafting.
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PMID:Combined inotropic effects of amrinone and epinephrine after cardiopulmonary bypass in humans. 821 47

The inotropic and vasodilating effects of amrinone can upset the balance of O2 supply and demand by changing those components in opposite directions simultaneously. We used a canine model of acute coronary artery occlusion to test our hypothesis that early administration of amrinone (before failure of the heart) would have beneficial effects on hemodynamic status and regional metabolism during ischemia, even before heart failure. Twenty dogs anesthetized with thiamylal were subjected to 50%, 75%, and 100% occlusion of the left anterior descending coronary artery. Half of the dogs were given a bolus injection of amrinone (0.75 mg/kg) 1-2 min before each occlusion, immediately followed by continuous infusion (10 micrograms.kg-1 x min-1) during occlusion; the other half did not receive amrinone (control). Hemodynamic and metabolic variables were measured in the ischemic area (the left anterior descending coronary artery) and in a nonischemic area (the circumflex vein). Amrinone not only decreased heart rate, left ventricular systolic and end-diastolic pressures, and mean pulmonary arterial pressure during constrictions but also maintained contractility, stroke volume index, and stroke volume index/left ventricular end-diastolic pressure before and during constrictions. Regional myocardial blood flow in ischemic areas decreased with amrinone during constrictions but was still higher than in untreated animals. Regional ischemic and nonischemic metabolic variables (metabolism of intracoronary potassium, CO2, O2, glucose, and lactate) were similar for both groups and changed to the same extent. Amrinone appears to improve left ventricular performance and increase blood flow to ischemic myocardium while not worsening regional metabolic effects during various grades of ischemia in the dog.
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PMID:Early administration of amrinone does not impair regional metabolism of O2 or lactate and, by improving myocardial performance, preserves myocardial blood flow in the ischemic canine heart. 849 55

The effects on the postischemic myocardium of amrinone and dobutamine were studied in canine hearts that underwent 90 minutes of hypothermic (10 degrees C) arrested ischemia. In an isolated heart preparation cross-circulated by a support dog, left ventricular pressure-volume loops were collected under a constant afterload based on a mock circulatory system and a range of preload conditions controlled by a computerized servo volume pump. Dobutamine (0, 5, 10, 15 micrograms/kg per minute) and amrinone (0, 0.75, 1.5, 3.0 mg/kg) were tested in this order based on the weights of the support dogs in eight experiments. Changes in intrinsic myocardial contractility were analyzed as percent increases in the preload recruitable stroke work area from baselines. Dobutamine exhibited significant dose-related increases in the preload recruitable stroke work area. Amrinone did not produce significant increases in preload recruitable stroke work area at 0.75 mg/kg; amrinone's inotropic effect was equivalent to dobutamine, 5 micrograms/kg per minute at 1.5 mg/kg, and at the maximum dose (3.0 mg/kg) it was equivalent to dobutamine, 10 micrograms/kg per minute. The myocardial energetic efficiency was determined from the analysis of the myocardial oxygen consumption-pressure volume area relationship. The y intercept represents the basal metabolic oxygen requirement of the unloaded beating heart, and the slope is inversely proportional to the rate of energy conversion for increasing loading conditions. Dobutamine significantly increased the y intercepts, but it had no effects on the slopes. These changes demonstrate reduced myocardial efficiencies that are consistent with previous reports. Amrinone (0.75 and 1.50 mg/kg) did not result in change of the y intercepts and the slopes of myocardial oxygen consumption-pressure-volume area relationship from baseline conditions. The y intercept was increased with amrinone (3.0 mg/kg), although still not significantly higher than baseline and not to the extents of the dobutamine group. Dobutamine did not have any primary effect on coronary resistance, while amrinone significantly reduced coronary resistance in all loading conditions at 1.5 and 3.0 mg/kg. This study demonstrates that the inotropic effects of amrinone tested under this constant afterload preparation were lower than those of dobutamine. Amrinone has a superior profile of myocardial efficiency on the postischemic myocardium since it does not produce the oxygen-wasting effects of the traditional inotropic agents such as the beta agonists. This benefit, together with amrinone's coronary dilating effects, critically improves the supply/demand ratio that may be of importance in certain clinical situations.
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PMID:The effects of amrinone versus dobutamine on myocardial mechanics and energetics after hypothermic global ischemia. 850 30

Amrinone, a phosphodiesterase III inhibitor, is known to exert inotropic and vasodilating effects. This study was undertaken to investigate the hemodynamic effects and optimal dose of amrinone in patients undergoing coronary artery bypass surgery. Seventeen patients with ejection fraction > 0.45 were included. In both group B and C, amrinone 0.5 mg.kg-1 was administered in the venous reservoir near the end of cardiopulmonary bypass (CPB), and doses of 1 and 5 micrograms.kg-1.min-1 by an intravenous infusion. Additional group of A did not receive amrinone. In group B, amrinone increased cardiac index by 79% and stroke index by 81% while decreased mean arterial pressure by 19% and systemic vascular resistance by 59% in comparison with group A. Heart rate did not increase. In group C, changes of hemodynamic variables were almost the same compared with group B. These data suggests that amrinone improves left ventricular performance without increasing myocardial oxygen demand while recovering from CPB. However, a high dose of amrinone should be used in combination with catecholamines because its vasodilating action is potentiated by hyperdynamic state after CPB.
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PMID:[Hemodynamic effects of amrinone during emergence from cardiopulmonary bypass]. 858 58

Low heart stroke volume syndrome is clinically manifested with hypoperfusion of all body systems. Inotropic or mechanical support is applied. Acute heart failure is one of the most important complications after open heart surgery. Catecholamines have been up to non considered as a therapy of choice for the acute heart failure. Effectiveness of catecholamines could be limited with some side effects. Phosphodiesterase inhibitors promise a new therapeutic approach. PDE III primary act through phosphodiesterase inhibition which leads to a rise of aAPM levels. Thus they show positive inotropic and lusitropic effects, which could be monitored by occlusive pulmonary capillary pressure values. Amrinone is obviously superior to inotropic catecholamines.
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PMID:[Hemodynamic effects of amrinone, dobutamine and dopamine in the cardiac low output syndrome following open-heart surgery]. 864 47

We compared the relative effects of dobutamine (5 micrograms/kg/min) and amrinone (1.0 mg/kg bolus followed by 10 micrograms/kg/min) on right and left ventricular function and pulmonary arterial pressures during weaning from cardiopulmonary bypass in patients with a mean preoperative pulmonary pressure > 30 mmHg. Twenty patients scheduled for mitral valve replacement were studied in a prospective, randomized, double-blind trial. Patients receiving amrinone had a greater increase in cardiac index (CI) of 1.38 (+/-0.95) litre/min/m2 at separation vs 0.69 (+/-0.63) litre/min/m2 in the dobutamine group (P < 0.05). The amrinone group also had a greater increase in right ventricular ejection fraction (0.15 +/- 0.08 at separation from cardiopulmonary bypass versus an increase of 0.04 +/- 0.11 in those receiving dobutamine; P < 0.005). Amrinone produced a larger decrease in pulmonary artery wedge pressure 8.0 (+/-4.4) mmHg vs 0.75 (+/-6.6) mmHg at separation; pulmonary artery systolic and diastolic pressures also were reduced more in the amrinone group. There were no differences in heart rate, mean arterial pressure, central venous pressure and right ventricular stroke work index between patient groups. In the doses chosen, the use of amrinone compared to dobutamine was associated with a reduction in pulmonary arterial pressures and an increase in cardiac index and right ventricular ejection fraction after separation from bypass in patients with severe preoperative pulmonary hypertension.
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PMID:Amrinone versus dobutamine in cardiac surgical patients with severe pulmonary hypertension after cardiopulmonary bypass: a prospective, randomized double-blinded trial. 920 4

Amrinone is a bipyridine compound with characteristic effects on the force-velocity relationship of fast skeletal muscle, including a reduction in the maximum shortening velocity and increased maximum isometric force. Here we performed experiments to elucidate the molecular mechanisms for these effects, with the additional aim to gain insight into the molecular mechanisms underlying the force-velocity relationship. In vitro motility assays established that amrinone reduces the sliding velocity of heavy meromyosin-propelled actin filaments by 30% at different ionic strengths of the assay solution. Stopped-flow studies of myofibrils, heavy meromyosin and myosin subfragment 1, showed that the effects on sliding speed were not because of a reduced rate of ATP-induced actomyosin dissociation because the rate of this process was increased by amrinone. Moreover, optical tweezers studies could not detect any amrinone-induced changes in the working stroke length. In contrast, the ADP affinity of acto-heavy meromyosin was increased about 2-fold by 1 mm amrinone. Similar effects were not observed for acto-subfragment 1. Together with the other findings, this suggests that the amrinone-induced reduction in sliding velocity is attributed to inhibition of a strain-dependent ADP release step. Modeling results show that such an effect may account for the amrinone-induced changes of the force-velocity relationship. The data emphasize the importance of the rate of a strain-dependent ADP release step in influencing the maximum sliding velocity in fast skeletal muscle. The data also lead us to discuss the possible importance of cooperative interactions between the two myosin heads in muscle contraction.
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PMID:Drug effect unveils inter-head cooperativity and strain-dependent ADP release in fast skeletal actomyosin. 1952 Aug 47


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