Comparison of the effects on arterial-ventricular coupling between phosphodiesterase inhibitor and dobutamine in the diseases human heart

Cardiac Mechanoenergetics in Patients with Acute Myocardial Infarction: From Pressure-Volume Loop Diagram Related to Cardiac Oxygen Consumption

Acute myocardial infarction (AMI) results in significant changes in cardiac structure and functions, leading to left ventricular remodeling and subsequent systolic and diastolic dysfunction. To improve current approaches in diagnoses, treatments, and prevention of cardiovascular diseases, a better understanding of cardiac mechanoenergetics, including systolic performance and energy demand, becomes paramount. In this review, we summarize cardiac mechanics, cardiac energetics, and their relationship in complications related to AMI using 2 important physiologic frameworks, pressure-volume loops and the Vo₂-pressure-volume area relationship diagram, as they are powerful tools for understanding physiologic behavior and mechanoenergetics of the left ventricle.

Ventriculoarterial decoupling in human septic shock

Introduction

Septic shock is the most severe manifestation of sepsis. It is characterized as a hypotensive cardiovascular state associated with multiorgan dysfunction and metabolic disturbances. Management of septic shock is targeted at preserving adequate organ perfusion pressure without precipitating pulmonary edema or massive volume overload. Cardiac dysfunction often occurs in septic shock patients and can significantly affect outcomes. One physiologic approach to detect the interaction between the heart and the circulation when both are affected is to examine ventriculoarterial coupling, which is defined by the ratio of arterial elastance (Ea) to left ventricular end-systolic elastance (Ees). In this study, we analyzed ventriculoarterial coupling in a cohort of patients admitted to ICUs who presented with vs without septic shock.

Methods

In this retrospective cross-sectional opportunity study, we measured routine hemodynamics using indwelling arterial and pulmonary arterial catheters and transthoracic echocardiograms in 25 septic patients (group S) and 25 non–septic shock patients (group C) upon ICU admission. Ees was measured by echocardiography using a single-beat (Ees_SB) method. Ea was calculated as 0.9 systolic arterial pressure/stroke volume, and then the Ea/Ees_SB ratio was calculated (normal value <1.36).

Results

In group S, 21 patients had an Ea/Ees_SB ratio >1.36 (uncoupled). The four patients with Ea/Ees_SB ratios ≤1.36 had higher Ees_SB values than patients with Ea/Ees_SB ratios >1.36 (P = 0.007), although Ea measurements were similar in both groups (P = 0.4). In group C, five patients had uncoupled Ea/Ees_SB ratios. No correlation was found between Ees_SB and left ventricular ejection fraction and between Ea/Ees_SB ratio and mixed venous oxygen saturation in septic shock patients.

Conclusions

Upon admission to the ICU, patients in septic shock often display significant ventriculoarterial decoupling that is associated with impaired left ventricular performance. Because Ea/Ees decoupling alters cardiovascular efficiency and cardiac energetic requirements independently of Ea or Ees, we speculate that septic patients with ventriculoarterial uncoupling may benefit from therapy aimed at normalizing the Ea/Ees ratio.

Population pharmacokinetics of olprinone in healthy male volunteers

BACKGROUND

Olprinone decreases the cardiac preload and/or afterload because of its vasodilatory effect and increases myocardial contractility by inhibiting phosphodiesterase III.

PURPOSE

The objective of this study was to characterize the population pharmacokinetics of olprinone after a single continuous infusion in healthy male volunteers.

METHODS

We used 500 plasma concentration data points collected from nine healthy male volunteers for the study. The population pharmacokinetic analysis was performed using the nonlinear mixed effect model (NONMEM®) software.

RESULTS

The time course of plasma concentration of olprinone was best described using a two-compartment model. The final pharmacokinetic parameters were total clearance (7.37 mL/minute/kg), distribution volume of the central compartment (134 mL/kg), intercompartmental clearance (7.75 mL/minute/kg), and distribution volume of the peripheral compartment (275 mL/kg). The interindividual variability in the total clearance was 12.4%, and the residual error variability (exponential and additive) were 22.2% and 0.129 (standard deviation). The final pharmacokinetic model was assessed using a bootstrap method and visual predictive check.

CONCLUSION

We developed a population pharmacokinetic model of olprinone in healthy male adults. The bootstrap method and visual predictive check showed that this model was appropriate. Our results might be used to develop the population pharmacokinetic model in patients.

Effective arterial elastance as an index of pulmonary vascular load

The aim of this study was to test whether the simple ratio of right ventricular (RV) end-systolic pressure (Pes) to stroke volume (SV), known as the effective arterial elastance ( Ea), provides a valid assessment of pulmonary arterial load in case of pulmonary embolism- or endotoxin-induced pulmonary hypertension. Ventricular pressure-volume (PV) data (obtained with conductance catheters) and invasive pulmonary arterial pressure and flow waveforms were simultaneously recorded in two groups of six pure Pietran pigs, submitted either to pulmonary embolism ( group A) or endotoxic shock ( group B). Measurements were obtained at baseline and each 30 min after injection of autologous blood clots (0.3 g/kg) in the superior vena cava in group A and after endotoxin infusion in group B. Two methods of calculation of pulmonary arterial load were compared. On one hand, Ea provided by using three-element windkessel model (WK) of the pulmonary arterial system [ Ea(WK)] was referred to as standard computation. On the other hand, similar to the systemic circulation, Ea was assessed as the ratio of RV Pes to SV [ Ea(PV) = Pes/SV]. In both groups, although the correlation between Ea(PV) and Ea(WK) was excellent over a broad range of altered conditions, Ea(PV) systematically overestimated Ea(WK). This offset disappeared when left atrial pressure (Pla) was incorporated into Ea [ Ea * (PV) = (Pes − Pla)/SV]. Thus Ea * (PV), defined as the ratio of RV Pes minus Pla to SV, provides a convenient, useful, and simple method to assess the pulmonary arterial load and its impact on the RV function.

Effects of Dopamine and Olprinone on Ventricular Energetics in Sevoflurane-Induced Acute Left Ventricular Depression in Dogs

OBJECTIVE

The purpose of this study was to compare the effects of dopamine and a new phosphodiesterase (PDE)-3 inhibitor, olprinone, on hemodynamics and myocardial energetics in dogs with acute myocardial depression.

DESIGN

Prospective, randomized, crossover study.

SETTING

University animal laboratory.

SUBJECTS

Mongrel dogs.

INTERVENTIONS

Eight open-chest, barbiturate-anesthetized dogs with instruments for measurement of left ventricular pressure and volume were exposed to 2 MAC (minimum alveolar concentration) of sevoflurane to induce acute myocardial depression. Each dog was randomly assigned for either infusion of dopamine (5 microg/kg/min) for 15 minutes or bolus of olprinone (10 microg/kg), followed by an infusion (0.3 microg/kg/min) for 30 minutes. Treatment was crossed over after a washout period of 90 minutes.

MEASUREMENTS AND MAIN RESULTS

For analysis of ventricular energetics, ventriculoarterial coupling was assessed using the ratio of arterial elastance to end-systolic pressure-volume relation and mechanical efficiency was calculated using the ratio of external work to pressure-volume area. Measurements were performed prior to sevoflurane administration, and before and after treatment. Two MAC of sevoflurane significantly impaired ventriculoarterial coupling and mechanical efficiency. Both olprinone and dopamine improved ventriculoarterial coupling and mechanical efficiency to similar degrees, but by different mechanisms. Olprinone improved ventricular energetics at a lower energy expenditure, probably because of olprinone's vasodilating effect, which augments energy transfer from the ventricle into the systemic circulation.

CONCLUSION

Although both dopamine and olprinone improve sevoflurane-induced impairment of ventricular energetics, olprinone accomplishes this with lower ventricular energy expenditure.

Assessment of arterial ventricular coupling changes in patients under therapy with various antihypertensive agents by a non-invasive echocardiographic method

BACKGROUND

The integration between arterial and ventricular function has been studied by mostly invasive techniques. We considered assessing the influence of various antihypertensive medications on arterial-ventricular coupling (AVC) with the use of a non-invasive echocardiographic method.

METHODS

A total of 9037 patients, who had been under treatment for essential arterial hypertension were studied echocardiographically at baseline prior to therapy and after 6 months of antihypertensive monotherapy (diuretics, beta-blockers without intrinsic sympathomimetic activity (ISA), beta-blockers with ISA, a-blockers, angiotensin converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (AIIRA), non-dihydropyridine calcium antagonists, and dihydropyridine calcium antagonists). The AVC was calculated by echocardiographic measurements based on the equation: AVC=ESV/SV (ESV, end systolic volume; SV, stroke volume).

RESULTS

ACEI, AIIRA, and dihydropyridine calcium antagonists decreased (P<0.0001 for all) while diuretics, alpha-blockers, both beta-blocker groups, and non-dihydropyridines increased significantly the AVC values compared to baseline measurements (P<0.0001 for all, except P=0.02 for alpha-blockers). Changes in AVC were the most highly correlated with changes in EF (r=-0.979, P<0.0001).

CONCLUSION

Various antihypertensive drugs have a differential effect on AVC with ACEI, AIIRA, and dihydropyridine calcium antagonists having the most favorable effect on this index. AVC provides a meaningful index of cardiovascular performance in hypertension and offers the possibility of wide employment and serial follow-up in large numbers of patients because of its completely non-invasive nature.

The cerebrovascular dilatation effects of olprinone, a phosphodiesterase III inhibitor, in comparison with acetazolamide—a pliot study

To examine the effects of olprinone, a phosphodiesterase III inhibitor, on cerebral blood flow (CBF), we compared the effects of olprinone on CBF to that of acetazolamide. Using technetium-99m-ethyl cysteinate dimer (99mTc-ECD) brain SPECT, we measured regional CBF (rCBF) at 33 sites, including 16 right and left pairs of non-infarct cerebral cortexes, in seven stroke patients (66.0+/-3.2 years) in a resting state and 15 min after the administration of acetazolamide. Within 1 week, rCBF at each site was measured 15 min after the initiation of olprinone infusion. Resting rCBF showed a significant negative correlation with the change in rCBF (DeltaCBF) during olprinone infusion (r = -0.43, P=0.013), but no significant correlation was seen following acetazolamide administration. The difference in rCBF between the right and left cortex increased more following acetazolamide administration (14.1+/-10.9 ml/(min 100 g)) than during olprinone infusion (5.4+/-4.8 ml/(min 100 g), P=0.013). The rCBF at four regions of interest (ROI) with low-resting CBF (< 49 ml/(min 100 g)) further decreased following the administration of acetazolamide. The vasodilatory effects of olprinone are dependent on resting CBF instead of on the intracerebral steal phenomenon that occurs with acetazolamide.

The Interaction of MCI-154, a Calcium Sensitizer, and Isoflurane on Systemic and Coronary Hemodynamics in Chronically Instrumented Dogs

We conducted this study to determine the interaction of MCI-154, 6-[4-(4'-pyridylamino)phenyl]-4,5-dihydro-3(2H)-pyridazinone hydrochloride, a calcium sensitizer, and isoflurane on myocardial contractility as well as systemic and coronary hemodynamics in chronically instrumented dogs after pharmacological autonomic nervous system activity blockade. MCI-154 increased heart rate and left ventricular function with no change in rate pressure product, pressure work index, and coronary blood flow, with a decrease in coronary vascular resistance (CVR) in the conscious state. Isoflurane decreased heart rate and left ventricular function, with a decrease in rate pressure product and pressure work index. Isoflurane also decreased CVR, but not coronary blood flow. The cardiovascular actions of MCI-154 during isoflurane anesthesia were qualitatively similar to those observed in the conscious state. In contrast to the finding in the conscious state, MCI-154 reversed the decrease in cardiac output and preload recruitable stroke work caused by isoflurane, but these are not significantly different from the effects of isoflurane alone. These results indicate that MCI-154 increases myocardial contractility and decreases CVR without changing calculated myocardial oxygen consumption during both the conscious state and isoflurane anesthesia.

IMPLICATIONS

MCI-154, a calcium sensitizer, restores the myocardial contractility depressed by isoflurane and enhances the coronary vasodilating effect of isoflurane in chronically instrumented dogs.

Olprinone, a phosphodiesterase III inhibitor, does not affect hypoxia-induced pial arteriolar dilatation in rabbits

PURPOSE

Olprinone, a phosphodiesterase III inhibitor, is used for the treatment of heart failure or asthma. Such patients may suffer from hypoxia. However, the effect of olprinone on the cerebral vasodilator response to hypoxia remains unclear.

METHODS

Rabbits were anesthetized and ventilated mechanically. The pial arteriolar diameter was determined using a cranial window and intravital microscopy. Hypoxia was induced twice in the same animal by reducing FIO(2) to 0.1. The first episode was induced during an infusion of saline, and the second during an infusion of saline (saline group; n = 8) or olprinone (1 microg x kg(-1) x min(-1), OLP1 group; n = 8 or 10 microg x kg(-1) x min(-1), OLP10 group; n = 8). The pial arteriolar responses to hypoxia were recorded and compared between the two episodes of hypoxia in each group.

RESULTS

Blood gas data in the first hypoxic challenge were identical to those in the second challenge in each group. Pial arteriolar diameter increased significantly during hypoxia. In arterioles between 50-100 microm diameter, first and second hypoxia-induced pial arteriolar dilatation in OLP1 were 13 +/- 6% and 10 +/- 7% respectively (P = 0.574 ) and those in OLP10 were 16 +/- 6% and 15 +/- 7% respectively (P = 0.606). In arterioles between 25-50 microm, the results were the same as in arterioles between 50-100 microm.

CONCLUSION

Olprinone does not affect the hypoxia-induced dilatation of pial arterioles in pentobarbital anesthetized rabbits.

Olprinone: a phosphodiesterase III inhibitor with positive inotropic and vasodilator effects

Olprinone is a newly developed phosphodiesterase III inhibitor characterized by several properties. First, olprinone has positive inotropic and vasodilator actions and improves myocardial mechanical efficiency. Second, olprinone augments cerebral blood flow by a direct vasodilatory effect on cerebral arteries. The cerebrovascular reactivity to olprinone is marked in patients with impaired cerebral circulation. Third, olprinone selectively improves carotid artery distensibility, which may be attributable to differences in the arterial structural components or the reactivity of smooth muscle cells to olprinone. Fourth, olprinone improves inadequate redistribution of brain perfusion and may prevent cerebral metabolic abnormalities in heart failure.

Effect of phosphodiesterase III inhibitor on contractility, afterload, and vascular capacitance during right heart bypass preparation

OBJECTIVES

Phosphodiesterase III inhibitors, which have both positive inotropic and vasodilatory effects, occasionally cause hypotension due to afterload reduction and possibly due to preload reduction caused by the increase in vascular capacitance.

METHODS

Six open-chest adult mongrel dogs were used to compare the effects on left ventricular contractility, afterload, and vascular capacitance of the phosphodiesterase III inhibitor, olprinone, with those of dobutamine using a right-heart-bypass model. Contractility and afterload were evaluated by the left ventricular pressure-volume relations with the use of a conductance catheter to derive the end-systolic elastance (Ees) and the effective arterial elastance (Ea). Vascular capacitance change was evaluated by reservoir volume change under a constant bypass flow (80 ml/kg per minute).

RESULTS

Ees increased significantly both with dobutamine (7.6 +/- 2.8 to 14.3 +/- 4.8 mmHg/ml, p < 0.05) and with olprinone (7.6 +/- 2.9 to 11.5 +/- 4.2 mmHg/ml, p < 0.05). Ea did not change with dobutamine (14.4 +/- 3.5 to 14.5 +/- 3.6 mmHg/ml, p = 0.9), whereas it decreased with olprinone (14.0 +/- 4.1 to 11.4 +/- 3.8 mmHg/ml, p = 0.093). Reservoir volume increased after the infusion of dobutamine (-94.0 +/- 39.8 ml), and decreased after the infusion of olprinone (-114.0 +/- 62.3 ml). The difference was statistically significant (p = 0.007). The reservoir volume change indicated that vascular capacitance decreased with dobutamine, and increased with olprinone.

CONCLUSIONS

Pre- and afterload reduction of olprinone combined with the positive inotropic effect are useful in treating congestive heart failure and managing low cardiac output syndrome after cardiac surgery.

Effects of olprinone, a new phosphodiesterase inhibitor, on gastric intramucosal acidosis and systemic inflammatory responses following hypothermic cardiopulmonary bypass

BACKGROUND

Phosphodiesterase (PDE) III inhibitors have both an inotropic and a peripheral vasodilatory effect, and also inhibit the activation of macrophages. Thus a newly developed PDE III inhibitor, olprinone, could modify gastric intramucosal pH (pHi), systemic oxygen consumption, and systemic inflammatory responses in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

We studied 23 patients. In 15 patients, olprinone (0.1 or 0.2 microg x kg(-1) x min(-1)) was administered from the commencement of CPB until their admission to the ICU. The other 8 patients received placebo. The pHi and regional CO2 tension (PrCO2) were assessed by a capnometric air tonometry. Systemic inflammatory responses were evaluated by serum interleukin-6 (IL-6), IL-10, and leucocyte counts.

RESULTS

The pHi and PCO2-gap, the difference between PrCO2 and arterial CO2 tension (PaCO2), showed a transient decrease and an increase after CPB, respectively. Although olprinone did not affect pHi, olprinone at 0.2 microg x kg(-1) x min(-1) significantly lessened post-CPB increase in PCO2-gap. Olprinone at 0.2 microg x kg(-1) x min(-1) significantly increased IL-10 and reduced the extent of leucocytosis, while it did not affect IL-6 levels. At the same dosage, olprinone also lessened the surge in systemic oxygen uptake index (VO2) and augmented the increase in mixed oxygen saturation (SvO2) both of which occurred after CPB. At 0.1 microg x kg(-1) x min(-1), however, olprinone did not show any significant effect.

CONCLUSION

Our results suggest that olprinone at 0.2 microg x kg(-1) x min(-1) suppresses gastric intramucosal acidosis and systemic inflammation following CPB.

The effects of olprinone (a phosphodiesterase III inhibitor) on hepatic vascular bed in a porcine model of endotoxemia

Decreased hepatic blood flow, and impaired hepatic oxygen delivery caused by endotoxin, result in hepatic metabolic deterioration followed by liver dysfunction and multiple organ failure. Among phosphodiesterase III inhibitors, only olprinone increases hepatosplanchnic blood flow. We evaluated the effects of olprinone on systemic hemodynamics, hepatic circulation, and hepatic oxygen delivery in a porcine model of endotoxemia. Fifteen pigs received a continuous infusion (1.7 microg. kg(-1). h(-1)) of endotoxin (lipopolysaccharide [LPS]) via the portal vein for 240 min. Seven of these pigs received olprinone infusion (0.3 microg. kg(-1). min(-1)) via a central vein from t = 150 min to t = 240 min, whereas the eight remaining pigs served as LPS controls. Continuous infusion of LPS caused significant reductions in hemodynamic variables and a significant increase in arterial lactate. After the administration of olprinone during the LPS infusion, portal venous flow and hepatic oxygen delivery were increased and were higher than in the LPS group. Furthermore, olprinone prevented any further increase in arterial lactate. We conclude that the administration of olprinone halted the disturbances in the hepatic circulation, especially in portal venous flow and hepatic oxygen delivery, in a porcine model of endotoxemia.

IMPLICATIONS

Endotoxin is a causative factor in peripheral vascular failure, resulting in a hemodynamic depression that includes a reduction in liver blood flow. The administration of olprinone (phosphodiesterase III inhibitor) improves the liver blood flow circulation in a porcine model of endotoxemia.

Different effects of olprinone on contractility in nonfatigued and fatigued diaphragm in dogs

PURPOSE

To evaluate the effects of low-dose olprinone, a phosphodiesterase III inhibitor, on contractility and its mechanism in nonfatigued and fatigued diaphragm in dogs.

METHODS

Thirty six pentobarbitone-anesthetized dogs were studied. In Group Ia (n=6), animals without fatigue, received no study drug. In Group Ib (n=6), dogs were given a bolus injection (10 ug x kg(-1)) followed by continuous infusion (0.1 microg x kg(-1) x min(-1)) of olprinone. In Groups IIa, IIb, and IIc (n=8 each), diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20-Hz applied for 30 min. After producing fatigue, Group IIa received no study drug; Group IIb was infused with olprinone (10 ug x kg(-1) loading dose plus 0.1 microg-kg(-1) min(-1) maintenance dose); Group IIc was infused with nicardipine (5 microg x kg(-1) x min(-1)) during olprinone administration. Diaphragmatic contractility was assessed by transdiaphragmatic pressure (Pdi).

RESULTS

No difference in Pdi was observed between Groups Ia and Ib. After fatigue, in Groups IIa, IIb, and IIc, Pdi at low-frequency (20-Hz) stimulation decreased from prefatigued (baseline) values (P < 0.05), whereas there was no change in Pdi at high-frequency stimulation (100-Hz). In Group IIb, during olprinone administration, Pdi at both stimuli increased from fatigued values (P < 0.05). In Group IIc, the augmentation of Pdi to each stimulus in fatigued diaphragm by olprinone was abolished with an infusion of nicardipine.

CONCLUSION

Low-dose olprinone does not affect contractility in nonfatigued diaphragm, but increases contractility in fatigued diaphragm via its effect on transmembrane calcium movement in dogs.

Effect of induction and reperfusion with warm substrate-enriched cardioplegia on ventricular function

BACKGROUND

This study tested the hypothesis that induction and reperfusion with warm substrate-enriched (IRWSE) blood cardioplegia improves postoperative left ventricular (LV) function in patients undergoing elective coronary bypass surgery (CABG).

METHODS

After giving informed consent, 67 patients scheduled for CABG surgery were randomized to either IRWSE + cold blood (CB) or CB alone. IRWSE cardioplegia consisted of 37 degrees C substrate-enriched (glutamate, aspartate, hyperkalemic) anterograde and retrograde blood cardioplegic solution followed by non-substrate-enriched cardioplegic solution given at 4 degrees C to 8 degrees C. LV function was measured with ventriculograms, volume conductance catheters, echocardiography, and multiple gated (image) acquisition.

RESULTS

The end-systolic pressure-volume relationship was improved postbypass in the IRWSE + CB group (CB, 1.5 +/- 0.74 mm Hg/mL vs IRWSE + CB, 2.1 +/- 1.2 mm Hg/mL; p = 0.042). The postoperative ejection fraction (EF%) was better preserved in the CB group (CB, 65 +/- 11.53% vs IRWSE + CB, 58.62 +/- 11.75%; p < 0.04).

CONCLUSIONS

Our results demonstrate a transient improvement in LV systolic function in the immediate postbypass period in CABG patients in the IRWSE + CB group. The intraoperative benefits of the IRWSE + CB technique did not persist in the postoperative period.

Effect of olprinone, a phosphodiesterase III inhibitor, on arterial wall distensibility: differentiation between aorta and common carotid artery

Although the effects of phosphodiesterase III (PDE III) inhibitors as vasorelaxants have been well documented, there are only few data on the wall response of different arteries. We evaluated the artery-specific effect of olprinone (OP), one of the PDE III inhibitors, on the major branches of human arteries and peripheral circulation. In 14 healthy subjects (average age: 57.5 +/- 21.2 years), systolic and diastolic diameters (Ds and Dd, respectively) and the time velocity integral (VI) of flow velocity patterns were measured by M-mode and Doppler echocardiography in the carotid artery (CA), the ascending aorta (asAo), the abdominal aorta (abAo), and the left ventricular outflow tract. Blood pressure (BP) was simultaneously measured using a cuff sphygmomanometer. Measurements were taken before and 20min after a bolus injection of OP (0.2 microg/kg). Distensibility (Ds - Dd), stiffness parameter beta (In(systolic BP/diastolic BP)/(Ds/Dd - 1)), cardiac output (CO: (Flow Area) x VI x HR at left ventricular outflow), selective flow volume (FV: (Flow Area) x VI x HR at CA or abAo), and vascular resistance (VR: mean BP/(CO or FV)) were then calculated. The distensibility increased significantly after OP administration (P = 0.0015), but that of the asAo or abAo did not change. Although there was a significant increase in CO (P = 0.001) and a significant decrease in systemic VR (P = 0.001) following OP administration, the FV and VR of both CA and abAo did not change significantly. The selectiveness of the effect of OP was demonstrated in terms of the CA wall distensibility. This was thought to be attributable to the differences in the structural components or the reactivity of smooth muscle cells to OP.

Hemodynamic effects of phosphodiesterase III inhibitor in patients with a large ventricular left-to-right shunt

The hemodynamic effects of olprinone, a newly synthesized phosphodiesterase (PDE) III inhibitor, were assessed in patients with a large cardiac left-to-right shunt. Ten patients with a large ventricular septal defect (VSD) were evaluated during cardiac catheterization. Olprinone was administered as a bolus, 20 microg/kg body weight, and hemodynamic data were obtained before and after the administration. Heart rate and systemic flow increased significantly after administration. On the other hand, olprinone significantly reduced left and right atrial pressure, the systolic pulmonary/arterial pressure ratio, and systemic vascular resistance. However, pulmonary flow and pulmonary vascular resistance were not changed. These results suggested that olprinone had a positive inotropic effect and selective vasodilator effect on patients with a large ventricular left-to-right shunt. Thus, PDE inhibitors may be beneficial for the treatment of patients with a large VSD.

Effect of olprinone, phosphodiesterase III inhibitor, on cerebral blood flow assessed with technetium-99m-ECD SPECT

Few clinical reports exist regarding the effects of phosphodiesterase III inhibitors on cerebral arteries. Therefore we used a [99mTc]-ECD brain SPECT and an ultrasound method to quantitatively evaluate cerebral and systemic flow dynamics after the administration of olprinone, a phosphodiesterase III inhibitor. In 15 patients (65 +/- 8 years, M/F = 13/2) with no abnormalities on a brain computed tomography (CT), cerebral blood flow and cardiac output were measured using [99mTc]-ECD brain SPECT and Doppler echocardiography, respectively. Measurements were repeated at baseline and after the administration of olprinone. Significant increases in cerebral blood flow (p = 0.0007) and cardiac output (p = 0.001) were observed, and systolic blood pressure (p = 0.02) and systemic vascular resistance (p = 0.002) significantly decreased. No significant correlation between the increase in cerebral blood flow and the increase in cardiac output was observed. The data indicate that olprinone has a direct vasodilator effect on the cerebral artery, which was little related to the increase in cardiac output in patients who had not experienced stroke.

Effects of the phosphodiesterase III inhibitors olprinone, milrinone, and amrinone on hepatosplanchnic oxygen metabolism

OBJECTIVE

To measure the hepatic venous oxygen saturation in patients after cardiac surgery and to compare the effects of olprinone (OLP), a newly synthesized phosphodiesterase III inhibitor, with those of milrinone (MIL) and amrinone (AMR) on hepatosplanchnic oxygen dynamics. Phosphodiesterase III inhibitors are used to improve the hemodynamic state after cardiac surgery. However, the effect of these agents on the hepatosplanchnic circulation has not been investigated thoroughly.

DESIGN

Prospective, randomized study.

SETTING

University hospital intensive care unit (ICU).

PATIENTS

Twenty-nine patients undergoing elective cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

In each patient, a 7.5-Fr oximeter catheter was placed in the hepatic vein via the right femoral vein. Catheterization was completed before admission to the ICU, and the study was performed 8 to 24 hrs after surgery, after obtaining stable systemic hemodynamics in the ICU. The patients were assigned randomly to three groups, and they received one of three drugs for 2 hrs (OLP group, 0.3 microg/kg/min of OLP; MIL group, 0.5 microg/kg/min of MIL; AMR group, 10 microg/kg/min of AMR). The authors did not change the patient's hemodynamic interventions, including catecholamines and vasodilators, throughout the study period. Arterial and hepatic venous blood gas data and hemodynamic data (via a pulmonary artery catheter) were obtained before and after drug infusion. Using these data, the authors calculated systemic oxygen delivery and consumption, the systemic oxygen extraction ratio and the hepatosplanchnic oxygen extraction ratio, and the change in hepatosplanchnic blood flow using Fick's equation. Although the increases in cardiac index were not significantly different among the three groups, hepatic venous oxygen saturation increased significantly only in the OLP group (from 47.1% +/-2.6% to 57.0% +/- 1.5% in the OLP group, from 48.4% +/- 2.3% to 50.9% +/- 2.6% in the MIL group, and from 49.8% +/- 3.6% to 50.8% + +/-.7% in the AMR group). The calculated hepatosplanchnic blood flow change was significantly larger in the OLP group than in the other groups (30.1% +/- 5.7% in the OLP group, 9.3% +/- 5.1% in the MIL group, and 2.6% +/- 6.5% in the AMR group).

CONCLUSIONS

These results suggest that OLP enhances hepatosplanchnic blood flow and thus may be beneficial in protecting the hepatosplanchnic organs after cardiac surgery.

Possible mechanisms underlying the vasodilatation induced by olprinone, a phosphodiesterase III inhibitor, in rabbit coronary artery

The possible mechanisms underlying the vasodilatation induced by olprinone, a phosphodiesterase type III inhibitor, were investigated in smooth muscle of the rabbit coronary artery. Isometric force and membrane potential were measured simultaneously using endothelium-denuded smooth muscle strips. Acetylcholine (ACh, 3 microM) produced a contraction with a membrane depolarization (15. 2+/-1.1 mV). In a solution containing 5.9 mM K(+), olprinone (100 microM) hyperpolarized the resting membrane and (i) caused the absolute membrane potential level reached with ACh to be more negative (but did not reduce the delta membrane potential seen with ACh, 15.2+/-1.8 mV) and (ii) attenuated the ACh-induced contraction. In a solution containing 30 mM K(+), these effects were not seen with olprinone. Glibenclamide (10 microM) blocked the olprinone-induced membrane hyperpolarization. 4-AP (0.1 mM) significantly attenuated the olprinone-induced resting membrane hyperpolarization but TEA (1 mM) had no such effect. Glibenclamide (10 +microM), TEA (1 mM) and 4-AP (0.1 mM), given separately, all failed to modify the inhibitory actions of olprinone on (i) the absolute membrane potential level seen with ACh and (ii) the ACh-induced contraction. It is suggested that olprinone inhibits the ACh-induced contraction through an effect on the absolute level of membrane potential achieved with ACh in smooth muscle of the rabbit coronary artery. It is also suggested that glibenclamide-sensitive, ATP-sensitive K(+) channels do not play an important role in the olprinone-induced inhibition of the ACh-induced contraction.

Effective arterial elastance of irregular beats during atrial fibrillation in canine left ventricle

Effective arterial elastance (E(a)) was originally defined as the end-systolic pressure (ESP)/stroke volume (SV) ratio of the left ventricle (LV). E(a) combined with LV contractility (E(max)), E(a)/E(max), proved to be powerful in analyzing the ventriculo-arterial coupling of normal and failing hearts in regular beats. However, E(a) sensitively changes with LV E(max), preload, and afterload widely changing among irregular beats. This has discouraged the use of E(a) during arrhythmia. However, we hypothesized that E(a) could serve as the effective afterload (not always arterial) elastance against ventricular ejection under arrhythmia. We tested this hypothesis by analyzing beat-to-beat changes in E(a) of irregular beats during electrically induced atrial fibrillation (AF) in normal canine in situ hearts. We newly found that during AF in each heart: 1) E(a) changed widely among irregular beats and became markedly high in weak beats with small SVs; 2) E(a) and E(a)/E(max) distributed non-normally with large skewness but 1/E(a) distributed more normally; 3) 1/E(a) correlated closely with end-diastolic volume, E(max) and preceding beat intervals; and 4) the reciprocal of mean 1/E(a) closely correlated with mean ESP/mean SV. These results support our hypothesis that E(a) can serve as the effective afterload elastance against ventricular ejection on a per-beat basis during AF. E(a)/E(max) can also quantify the ventriculo-afterload (not arterial) coupling on a per-beat basis. This study, however, warns that mean E(a) and mean E(a)/E(max) of irregular beats cannot necessarily represent their averages during AF.

Beneficial effects of heart rate reduction on cardiac mechanics and energetics in patients with left ventricular dysfunction

It has been shown recently that the force-frequency relationship is blunted in experimental heart failure models. Furthermore, tachycardia is thought to have adverse effects on the diseased heart for several reasons, one of which is an increase in myocardial oxygen consumption. Inversely, the oxygen-saving effects of bradycardia may be beneficial for the treatment of heart failure. The aim of this study was to elucidate how heart rate (HR) modulates cardiac mechanics and energetics in patients with left ventricular (LV) dysfunction. LV pressure-volume data and myocardial oxygen consumption (MVO2) was assessed using conductance and coronary sinus thermodilution catheters in 14 patients with moderate LV dysfunction (mean ejection fraction 34%) under 3 conditions: (a) basal, (b) HR increased by 20% using atrial pacing, and (c) HR decreased by 16% using a specific bradycardic agent, zatebradine (7.5 mg p.o.). Atrial pacing decreased external work (EW) (from 0.39 to 0.31 J beat(-1) m(-2), p<0.05) at a comparable MVO2 per beat with a marginal increase in LV contractility index (Ees) (from 2.34 to 2.76 mm Hg ml(-1) m(-2), p = 0.08), resulting in a decrease in mechanical efficiency (EW/MVO2) (from 25.9 to 22.1%, p<0.05). In contrast, zatebradine did not decrease Ees (from 2.34 to 2.24 mm Hg ml(-1) m(-2), NS), but increased EW (from 0.39 to 0.42 J beat(-1) m(-2), p<0.05 vs. basal level) without a change in MVO2 per beat, resulting in improved mechanical efficiency (from 25.9 to 29.7%, p<0.05 vs. basal level). These results suggest that mild bradycardia is energetically advantageous and does not decrease myocardial contractility and performance, whereas pacing-induced tachycardia worsens cardiac mechanics and energetics in patients with LV dysfunction. Thus, the oxygen-saving effect of bradycardia may be beneficial for the treatment of heart failure.

Diuretic effect of phosphodiesterase inhibitors depends on baseline renal function in patients with congestive heart failure

We examined the diuretic effects of phosphodiesterase inhibitors in heart failure patients with and without renal failure. We found that, despite the improvement in central hemodynamics, phosphodiesterase inhibitors do not necessarily facilitate diuresis in heart failure in patients with concomitant renal failure.

Impact of vascular adaptation to chronic aortic regurgitation on left ventricular performance

BACKGROUND

This investigation was designed to test the hypothesis that vascular adaptation occurs in patients with chronic aortic regurgitation to maintain left ventricular (LV) performance.

METHODS AND RESULTS

Forty-five patients with chronic aortic regurgitation (mean age 50+/-14 years) were studied using a micromanometer LV catheter to obtain LV pressures and radionuclide ventriculography to obtain LV volumes during multiple loading conditions and right atrial pacing. These 45 patients were subgrouped according to their LV contractility (Ees) and ejection fraction values. Group I consisted of 24 patients with a normal Ees. Group IIa consisted of 10 patients with impaired Ees values (Ees <1.00 mm Hg/mL) but normal LV ejection fractions; Group IIb consisted of 11 patients with impaired contractility and reduced LV ejection fractions. The left ventricular-arterial coupling ratio, Ees/Ea, where Ea was calculated by dividing the LV end-systolic pressure by LV stroke volume, averaged 1.60+/-0.91 in Group I. It decreased to 0.91+/-0.27 in Group IIa (P<0.05 versus Group I), and it decreased further in Group IIb to 0.43+/-0.24 (P<0.001 versus Groups I and IIa). The LV ejection fractions were inversely related to the Ea values in both the normal and impaired contractility groups (r=-0.48, P<0.05 and r=-0.56, P<0.01, respectively), although the slopes of these relationships differed (P<0.05). The average LV work was maximal in Group IIa when the left ventricular-arterial coupling ratio was near 1.0 because of a significant decrease in total arterial elastance (P<0.01 versus Group I). In contrast, the decrease in the left ventricular-arterial coupling ratio in Group IIb was caused by an increase in total arterial elastance, effectively double loading the LV, contributing to a decrease in LV pump efficiency (P<0.01 versus Group IIa and P<0.001 versus Group I).

CONCLUSIONS

Vascular adaptation may be heterogeneous in patients with chronic aortic regurgitation. In some, total arterial elastance decreases to maximize LV work and maintain LV performance, whereas in others, it increases, thereby double loading the LV, contributing to afterload excess and a deterioration in LV performance that is most prominent in those with impaired contractility.

Effects of phosphodiesterase inhibitors after coronary artery bypass grafting

The aim of this study was to estimate the postoperative effects of phosphodiesterase (PDE) inhibitors (milrinone and olprinone) after coronary artery bypass grafting (CABG). To prevent hypotension caused by the PDE inhibitors, low dose of catecholamines were used concomitantly. A total of 34 elective CABG cases were tested. In 12 cases, 0.25 microg kg(-1) min(-1) of milrinone, 3 microg kg(-1) min(-1) of dobutamine (DOB) and dopamine (DOA) were used concomitantly (Group-M). In another 10 patients, 0.1 microg kg(-1) min(-1) of olprinone and the same doses of the catecholamines were infused (Group-O). As a control, the same doses of DOA and DOB only were administered in 12 patients (Group-C). When the pump flow of the cardiopulmonary bypass (CPB) decreased to half, these drugs were given in all groups. Hemodynamics were recorded before CPB, just after the operation, and 3, 6, 12, 24, 48 and 72 h after the operation. Both milrinone and olprinone increased the cardiac index and decreased systemic vascular resistance to almost the same degree. Olprinone decreased mean aortic and pulmonary artery pressures, and also significantly reduced the preload of both right and left heart compared with milrinone. Significant hypotension was not detected due to the concomitant usage of low-dose catecholamines. This concomitant usage of PDE inhibitors and catecholamines allowed easy weaning from CPB, demonstrating excellent hemodynamics after CABG. Good oxygen demand and supply balance were maintained in peripheral tissue. These results suggest that these new PDE inhibitors may be effective not only for weaning from CPB but also for post-cardiotomy cardiogenic shock.

Use of transesophageal echocardiography for postoperative evaluation of right ventricular function

BACKGROUND

No method has been available to assess the right ventricular (RV) pressure-volume relation in the operating room or intensive care unit. Left ventricular cross-sectional area measured by echocardiography using the technology of automated border detection has been used to construct left ventricular pressure-area (P-A) loops. In the human right ventricle, however, this approach has not been validated.

METHODS

We recorded RV P-A loops in 14 patients in the intensive care unit using transesophageal echocardiography. Multiple RV P-A loops were obtained by reducing preload with intravenous nitroglycerin, thereby elucidating the end-systolic P-A relation.

RESULTS

With an incremental dose of dobutamine, the slope of the RV end-systolic P-A relation increased (from 4.56+/-2.42 to 7.34+/-3.62 mm Hg/cm2, p<0.01), with no change in the x-axis intercept, which implied increased contractility. Furthermore, in the operating room we validated the use of RV cross-sectional area as a surrogate for RV volume by demonstrating the close correlation between the stroke area (maximal RV area minus minimal RV area) and stroke volume (r = 0.962; p<0.0001).

CONCLUSIONS

Transesophageal echocardiography with automated border detection is a promising tool for elucidating RV function through the analysis of RV P-A loops.

Vasorelaxant effect of olprinone, an inhibitor of phosphodiesterase 3, on mesenteric small artery and vein of rabbits

The effects of olprinone, a cardiotonic agent that inhibits cyclic GMP (cGMP)-inhibited phosphodiesterase, was studied on isolated rabbit mesenteric small artery and vein. In the presence of indomethacin and propranolol, olprinone at concentrations of 10 nM to 10 microM and 1 microM to 100 microM relaxed norepinephrine-stimulated mesenteric artery and vein in a concentration-dependent manner, respectively. The relaxation was not endothelium-dependent in the artery. Removal of the endothelium, however, increased marginally the response of the vein to olprinone. Olprinone-induced relaxation was less pronounced in arteries contracted with high KCl solution + norepinephrine than in those contracted with norepinephrine alone. Nicardipine inhibited this attenuating effect of high KCl solution on the olprinone-induced relaxation. Olprinone (1 microM) enhanced the relaxation of artery and vein in response to a cAMP-increasing agent, 6-(3-dimethylaminopropionyl) forskolin (NKH477), but not to a cGMP- increasing agent, glyceryl trinitrate. Norepinephrine (10 microM) and caffeine (5 mM) elicited a transient, phasic contraction of the artery in Ca2+-free solution. Both olprinone and NKH477 attenuated more potently the norepinephrine-induced contraction than the caffeine-induced contraction. When norepinephrine (10 microM) and caffeine (5 mM) were successively applied in Ca2+-free solution, the contractile effect of caffeine was diminished compared to that in artery which had not been pretreated with norepinephrine. When the contraction in response to norepinephrine was partially attenuated by 1 microM olprinone, the following contraction evoked by caffeine was enlarged. It is concluded that olprinone relaxes the small artery more strongly than the vein via its direct action on smooth muscles. It is suggested that olprinone attenuates norepinephrine-induced contraction through inhibition of receptor-operated transmembrane Ca2+ influx and Ca2+ release from intracellular storage sites.

Effects of amrinone, a phosphodiesterase inhibitor, on right ventricular/arterial coupling immediately after cardiac operations

OBJECTIVE

Amrinone, a selective phosphodiesterase III inhibitor, is reported to have a potent inotropic effect on the left ventricle, but the effects of this drug on right ventricular contractility in the clinical setting are unknown. The concept of ventricular/arterial coupling was applied to investigate the effects of amrinone on right ventricular contractility and afterload with transesophageal echocardiography.

METHODS AND RESULTS

The study was performed in the intensive care unit with 11 patients who had undergone cardiac operations. Right ventricular cross-sectional area was measured with transesophageal echocardiography equipped with a capability of automated border detection as a surrogate for right ventricular volume. Multiple pressure-area loops were obtained by reducing preload to measure end-systolic elastance and effective arterial elastance. External work and pressure-volume area were also measured to calculate the efficiency of energy transfer from pressure-volume area to external work. Nitroprusside (0.3 to 0.5 microg x kg(-1) x min(-1)) and amrinone (1 mg x kg(-1) intravenously followed by 10 microg x kg(-1) x min(-1)) were administered. With nitroprusside infusion, end-systolic elastance and effective arterial elastance remained unchanged (end-systolic elastance, 4.73 +/- 2.18 mm Hg/cm2 to 4.65 +/- 2.09 mm Hg/cm2; effective arterial elastance, 8.05 +/- 3.84 mm Hg/cm2 to 7.70 +/- 3.64 mm Hg/cm2). In contrast, amrinone reduced afterload (effective arterial elastance, 8.82 +/- 3.99 mm Hg/cm2 to 7.05 +/- 4.01 mm Hg/cm2, p = 0.004) and enhanced contractility (end-systolic elastance, 4.47 +/- 1.79 mm Hg/cm2 to 6.56 +/- 2.22 mm Hg/cm2, p = 0.007). Consequently, amrinone decreased the ventricular/arterial coupling ratio (effective arterial elastance/end-systolic elastance, 2.40 +/- 1.45 to 1.16 +/- 0.63, p = 0.009) and improved the efficiency of energy transfer (external work/pressure-volume area, 0.44 +/- 0.15 to 0.54 +/- 0.15, p = 0.013).

CONCLUSIONS

Right ventricular pressure-area relations obtained with transesophageal echocardiography could successfully separate the simultaneous change in right ventricular systolic mechanics and afterload caused by amrinone. Amrinone caused enhancement of right ventricular contractility and afterload reduction.

Left ventricular-arterial system coupling at peak exercise in dilated nonischemic cardiomyopathy

We assessed the ventricular-arterial coupling at peak exercise in 20 patients with dilated cardiomyopathy (ejection fraction, 27+/-12%) and 7 normal subjects by radionuclide ventriculography during exercise, coupled with respiratory gas analysis. The end-systolic pressure-volume ratio, taken as an index of contractility, and the effective arterial elastance were calculated at rest and at peak exercise. The end-systolic pressure/volume ratio increased from 3.7+/-2.7 to 6.9+/-4.0 mm Hg/mL at peak exercise in the normal subjects, but did not change significantly (from 0.9+/-0.5 to 1.0+/-0.6 mm Hg/mL) in the patients. Arterial elastance did not change significantly in the patients (+17+/-32%, not significant [NS] vs rest) or in the normal subjects (+22+/-28%, NS vs rest). The change in ejection fraction during exercise correlated both with the end-systolic pressure/volume ratio and with effective arterial elastance changes (r=0.60 and 0.68, respectively). We conclude that ventricular arterial coupling is further altered at peak exercise in these patients because of the lack of increase in contractility and not of altered effective arterial elastance response.

Effects of a new cardiotonic phosphodiesterase III inhibitor, olprinone, on cardiohemodynamics and plasma hormones in conscious pigs with heart failure

We examined the effects of a novel phosphodiesterase III inhibitor, olprinone, on the cardiohemodynamics and plasma hormones in conscious pigs with pacing-induced heart failure. After pacing for 5-10 days, cardiac output (CO) decreased from 2.25 +/- 0.17 to 1.67 +/- 0.13 L/min (n = 8, p < 0.01) and stroke volume (SV) decreased from 20.1 +/- 2.1 to 12.0 +/- 1.6 ml (n = 8, p < 0.01), whereas left arterial pressure (LAP) increased from 2.8 +/- 1.2 to 16.7 -/+ 0.9 mm Hg (n = 7, p < 0.001) and systemic vascular resistance (SVR) increased from 38.7 +/- 3.5 to 49.8 +/- 4.2 mm Hg/L/min (n = 8, p < 0.01). Sequential intravenous infusions of 0.03, 0.3, and 3.0 microg/kg/min of olprinone at 30-min intervals to eight pigs caused dose-dependent increases in the decreased CO, SV, and maximal rate of rise in left ventricular pressure (LV dP/dt(max)) and decreased the elevated LAP and SVR. Olprinone at 3.0 microg/kg/min maximally increased CO, SV, and LV dP/dt(max) by 40.0 +/- 10.8% (p < 0.05 vs. vehicle), 25.6 +/- 6.9% (p < 0.05), and 43.9 +/- 11.2% (p < 0.01), respectively, and brought about a slight increase in heart rate and decreases in LAP and SVR, by 35.9 +/- 7.3% (p < 0.001) and 27.9 +/- 4.8% (p < 0.01), respectively. Olprinone did not affect the rate-pressure product. In addition, olprinone produced significant decreases in the plasma levels of atrial natriuretic peptide and cyclic guanosine monophosphate, with no changes in the plasma levels of cyclic adenosine monophosphate and catecholamines or plasma renin activity. These findings indicate that the short-term intravenous infusions of olprinone ameliorated the decreased left ventricular function without affecting myocardial oxygen consumption or the sympathetic nervous system in conscious pigs with heart failure.

Beneficial effects of a Ca2+ sensitizer, MCI-154, on the myocardial oxygen consumption-cardiac output relation in patients with left ventricular dysfunction after myocardial infarction: comparison with dobutamine and phosphodiesterase inhibitor

Although conventional inotropic agents such as catecholamines increase myocardial oxygen consumption, a newly developed inotropic agent, a Ca2+ sensitizer, may be able to increase cardiac output with less myocardial oxygen consumption. By using right-side heart catheterization, we assessed the ratio of the increase in myocardial oxygen consumption per unit increase in cardiac output during beta-adrenergic receptor stimulation (dobutamine, n = 15), phosphodiesterase inhibition (E-1020, n = 10), and Ca2+ sensitization (MCI-154, n = 17) in patients with coronary artery disease. Dobutamine increased cardiac output and myocardial oxygen consumption. E-1020 increased cardiac output but did not change myocardial oxygen consumption. MCI-154 increased cardiac output and decreased myocardial oxygen consumption. The oxygen cost of increasing cardiac output with dobutamine and with E-1020 was different from that with dextran infusion (n = 18); in contrast, the oxygen cost with MCI-154 was significantly smaller. Thus a newly developed Ca2+ sensitizer, MCI-154, may be beneficial for the treatment of heart failure.

Oxygen-saving effect of a new cardiotonic agent, MCI-154, in diseased human hearts

OBJECTIVES

The aim of this study was to examine the left ventricular mechanoenergetic effects of a novel Ca2+ sensitizing agent, MCI-154, on diseased human hearts compared with dobutamine.

BACKGROUND

Unlike conventional cardiotonic agents, a Ca2+ sensitizer that could produce a positive inotropic action by altering the responsiveness of myofilament to Ca2+ could generate force with smaller amounts of Ca2+; thus, it may potentially save energy expenditure.

METHODS

The left ventricular pressure-volume relation and myocardial oxygen consumption per beat (Vo2) were measured by a conductance (volume) catheter and a Webster catheter. Left ventricular contractility (Emax), systolic pressure-volume area (PVA [index of left ventricular total mechanical energy]) and Vo2 were assessed before and after infusion of MCI-154 or dobut-amine. The PVA-independent Vo2 (Vo2 mainly for excitation-contraction coupling) was assessed as the Vo2 at zero PVA.

RESULTS

Both agents increased Emax comparably (dobutamine: from 3.55 +/- 1.10 [mean +/- SD] to 5.04 +/- 1.16 mm Hg/ml per m2, p < 0.0001; MCI-154: from 3.36 +/- 1.26 to 5.37 +/- 2.14 mm Hg/ml per m2, p < 0.0001); dobutamine increased total Vo2 (from 0.22 +/- 0.08 to 0.27 +/- 0.09 ml O2, p < 0.05) and PVA-independent Vo2 (from 0.019 +/- 0.019 to 0.091 +/- 0.051 ml O2, p < 0.005); but MCI-154 did not change these variables significantly. Consequently, the oxygen cost of contractility (delta PVA-independent Vo2/delta Emax) was less with MCI-154 than with dobutamine (0.14 +/- 0.18 vs. 1.10 +/- 0.80 J/mm Hg per ml per m2, p < 0.05).

CONCLUSIONS

These results suggest that the cardiotonic action mediated by MCI-154 could provide an energetic advantage over the conventional cardiotonic action with currently used inotropic agents.

A novel inotropic vasodilator, OPC-18790, reduces myocardial oxygen consumption and improves mechanical efficiency with congestive heart failure

We analyzed the left ventricular (LV) pressure-volume relation and obtained direct measurements of myocardial oxygen consumption (MVO2) before and after drug administration in 21 patients with New York Heart Association functional class II to III congestive heart failure to compare the mechanoenergetic effects of OPC-18790, a novel inotropic agent, and dobutamine. Pressure-volume data were obtained by the conductance method, and MVO2 measurements were obtained with a double-thermistor coronary sinus catheter before and after administration of OPC-18790 and dobutamine. The LV end-diastolic volume index decreased significantly without an increase in the heart rate after administration of OPC-18790, unlike that after administration of dobutamine. Both drugs significantly increased the LV contractility index (Emax) and caused similar improvements in ventricular-arterial coupling. OPC-18790 significantly reduced MVo2, whereas dobutamine increased MVo2. The ratio of the pressure-volume area to myocardial oxygen consumption (PVA/MVo2) remained unchanged after administration of OPC-18790 and decreased after administration of dobutamine. The ratio of external work to the pressure-volume area (EW/PVA) was similarly increased by both drugs, resulting in an improvement in mechanical efficiency (EW/MVo2) with OPC-18790 (p < 0.05) and in a deterioration with dobutamine (p < 0.05). OPC-18790 had an energetic advantage over dobutamine in spite of its positive inotropic effect. Our findings suggest that OPC-18790 may be useful for the treatment of patients with congestive heart failure.