The use of vasoactive therapy for acute decompensated heart failure: hemodynamic and renal considerations

Although diuretics remain the most commonly used intravenous medication for acute decompensated heart failure, vasoactive agents play an important role in select patient populations. Inotropes and pressor agents are critical in order to maintain blood pressure and cardiac output in a small subset of patients, and can preserve and even improve renal function. However, they should not be used in the majority of patients with preserved cardiac output. Vasodilators improve hemodynamics and symptoms in normotensive individuals. Their influence on renal function is less clear cut, although more recent data suggest a neutral effect.

Sustained use of nesiritide to aid in bridging to heart transplant

Patients with end-stage heart failure awaiting heart transplant are often maintained on continuous intravenous inotropic therapy. However, this therapy alone is often inadequate for maintenance of appropriate pulmonary artery pressure and stable clinical course. Nesiritide, B-type natriuretic peptide, is a recently released intravenous vasodilator for short-term use in patients with decompensated heart failure. This report details experience in four patients in whom this agent was used to bridge to transplant for prolonged periods (11-35 days) with added clinical benefit and without obvious tolerance. This suggests that new strategies for pretransplant management may be needed.

Racial Differences in the Characteristics of Patients Admitted for Acute Decompensated Heart Failure and Their Relation to Outcomes: Results From the OPTIME-CHF Trial

BACKGROUND

Recent data suggest that differences in response to therapy and survival exist between African Americans and Caucasians with heart failure. Whether these differences exist in acute decompensated heart failure (ADHF) is uncertain.

METHODS AND RESULTS

We analyzed data from the OPTIME-CHF (Outcomes of a Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure) study, a randomized trial of intravenous milrinone versus placebo in 949 patients hospitalized with ADHF. We evaluated differences in clinical characteristics, outcomes, and response to milrinone therapy in African American patients compared with Caucasians. The primary end point of OPTIME-CHF was days hospitalized for cardiovascular causes or death within 60 days of randomization. Thirty-three percent (n = 310) of patients were African American. African American patients were younger (57 vs. 70 years, P < .0001) and more likely to have non-ischemic cardiomyopathy (74% vs. 36%, P < .0001). In unadjusted analysis, African American patients had a lower 60-day mortality (5% vs. 12%, P = .0004) and tended to have better overall clinical outcomes. After adjustment for baseline differences, however, these differences were no longer significant. We found no differential effect of milrinone therapy by race.

CONCLUSION

African American patients with acute decompensated heart failure present with a different clinical profile than Caucasian patients. Although unadjusted clinical outcomes are better for African Americans presenting with ADHF, these differences diminished after adjustment for baseline characteristics.

Treatment of ischaemic left ventricular dysfunction with milrinone or dobutamine administered during coronary artery stenosis in the presence of beta blockade in pigs †

BACKGROUND

This study examines the effects of phosphodiesterase type III (PDEIII) inhibition vs beta stimulation on global function of the left ventricle (LV) and systemic haemodynamics in a porcine model of acute coronary stenosis with beta blockade.

METHODS

A total of 18 adult swine were anaesthetized. Micromanometer-tipped catheters were placed in the ascending aorta and LV. Two pairs of ultrasonic dimension transducers were placed in the subendocardium on the short axis proximal to a left anterior descending (LAD) artery occluder and the long axis of the LV. Before ischaemia, i.v. esmolol was infused to decrease baseline heart rate (HR) by approximately 25%, and all animals received an esmolol infusion (150 microg kg(-1) min(-1)). Ischaemia was produced by reducing the flow in the LAD artery by approximately 80%, from 17(4) to 3(2) ml min(-1). Animals were randomized to receive (after esmolol) one of the following: no drug, sham only (Group 1, n=6), control (C); 50 microg kg(-1) i.v. milrinone (Group 2, n=6) followed by 0.375 microg kg(-1) min(-1) (M); or incremental doses of dobutamine (Group 3, n=6) every 10 min (5, 10 and 20 microg kg(-1) min(-1)) (D). Left ventricular function data obtained included HR, arterial and LV pressures, cardiac output (CO), Emax and dP/dT. Measurements were taken during five time periods: before ischaemia (at baseline, after esmolol) and every 10 min during ischaemia (at 10, 20 and 30 min).

RESULTS

The effects of beta blockade and ischaemia had a significant impact on contractility (Emax) in Group M and myocardial performance (left ventricular end-diastolic pressure, LVEDP) in all groups. Left ventricular function (Emax, CO, LVEDP and SVR) was better preserved when milrinone was added in Group M. A moderate dose of dobutamine (10 microg kg(-1) min(-1)) increased CO. Only the high dose (20 microg kg(-1) min(-1)) improved contractility (Emax), but at the expense of increased SVR. Also, LVEDP with either dose of dobutamine remained high and unchanged.

CONCLUSIONS

From our limited findings, it would appear that there may, theoretically, be some benefit for using milrinone in preference to other inotropic drugs in the presence of beta blockade. Milrinone administration should be considered in patients with acute ischaemic LV dysfunction and preexisting beta blockade before using other inotropic drugs such as beta stimulants.

Chronic inotropic therapy in end-stage heart failure

BACKGROUND

Interventions in advanced heart failure that provide symptom relief and decrease hospital readmission are important. Chronic intravenous inotropic therapy represents a pharmacologic approach that has been advocated for palliative treatment. However, little is known about associated mortality and cost. Therefore, we sought to describe the impact of chronic infusions on resource use and survival.

METHODS

Data were reviewed for a 17-state Medicare region from 1995 to 2002. We obtained hospital and outpatient expenditures accrued up to 180 days before and after the initiation of chronic infusions. Health care use was defined by dollars reimbursed for drug and hospitalizations per beneficiary. Average accumulated cost curves were generated for dollars reimbursed for drug and for hospitalizations by days at risk.

RESULTS

The mean age of the cohort (n = 331) was 69.1 +/- 11.3 years. Mortality exceeded 40% at 6 months. Reductions in hospital days were observed at all time points. The amounts reimbursed at 30 and 60 days before and after initiation of inotrope favor drug therapy; however, at six months, the amounts reimbursed were greater due to the cost of milrinone.

CONCLUSIONS

Chronic intravenous inotrope use was associated with a high mortality. The cost for milrinone was significant, but there was a decrease in expenditures for subsequent hospitalizations. In the absence of appropriately designed clinical trials, the data suggest that the decision to use inotropes, the choice of inotrope, and the duration of treatment should reflect the impact on resource use.

Milrinone improves oxygenation in neonates with severe persistent pulmonary hypertension of the newborn

BACKGROUND

Many neonates with severe persistent pulmonary hypertension of the newborn (PPHN) are nonresponders to inhaled nitric oxide (iNO). Milrinone is a promising adjunctive therapy because of its pulmonary vasodilator properties and cardiotropic effects.

DESIGN

Case series of neonates with severe PPHN (defined as oxygenation index [OI] >20, failure of iNO therapy, and echocardiographic confirmation of PPHN).

SETTING

Tertiary neonatal intensive care unit.

SUBJECTS

Full-term (> or =37 weeks) neonates with severe PPHN who received intravenous milrinone.

MEASUREMENTS

The primary end point was the effect of intravenous milrinone on OI and hemodynamic stability over a 72-hour study period. Secondary end points examined included duration of iNO and degree of cardiorespiratory support.

RESULTS

Nine neonates at a mean gestation of 39.25 +/- 2.76 weeks, birth weight of 3668 +/- 649.1 g, and baseline OI of 28.1 +/- 5.9 received milrinone treatment after a poor initial response to iNO treatment. Intravenous milrinone was commenced at a median age of 21 hours (range, 18-49 hours), and patients were treated for median of 70 hours (range, 23-136). Oxygenation index was significantly reduced after milrinone treatment, particularly in the immediate 24 hours of treatment (8.0 +/- 6.6, P < .001). There was a significant improvement in heart rate (179 +/- 15.2 vs 149.6 +/- 22.4, P < .001) over the same period. Infants who received milrinone did not develop systemic hypotension; in fact, there was a nonsignificant trend toward improved blood pressure.

CONCLUSIONS

Intravenous milrinone produces early improvements in oxygenation without compromising systemic blood pressure.

Outpatient continuous inotrope infusion as an adjunct to heart failure therapy in Duchenne muscular dystrophy

We report the use of continuous intravenous inotrope infusion as a palliative management strategy for the treatment of symptomatic, refractory, end stage cardiac dysfunction in patients with Duchenne muscular dystrophy. Milrinone and/or dobutamine administered by continuous intravenous infusion provided symptomatic and objective cardiovascular improvement up to 30 months in 3 individuals with Duchenne muscular dystrophy and severe dilated cardiomyopathy. Continuous inotrope infusion should be considered a practical treatment strategy for end stage cardiac dysfunction in Duchenne muscular dystrophy patients when cardiac transplantation is not a viable option.

Proper use of phosphodiesterase inhibitors according to the situations

We came across a case who because of sustained hypotension with normal cardiac output was given amrinone which offered an initial excellent response but showed impotency later and its replacement by milrinone dramatically improved the hemodynamic status. The ensuing hypotension was thought to be the consequence of the use of amrinone which was given to treat hypotension in conjunction with fluid therapy; besides, it also induced pulmonary hypertension. Therefore, milrinone was given to replace amrinone and was successfully to turn the tide. It is our suggestion that if the use of a phosphodiesterase (PDE) inhibitor is indicated but its side effects are enhanced to refute its use, the application of a different PDE inhibitor should be kept in mind.

Outpatient continuous parenteral inotropic therapy as bridge to transplantation in children with advanced heart failure

BACKGROUND

Advanced heart failure in children is associated with high morbidity and mortality and is often refractory to standard medical therapy. The purpose of this study was to review our institutional experience with the use of outpatient parenteral inotropic therapy (PIT) for advanced chronic heart failure in children.

METHODS AND RESULTS

We reviewed the medical records of all patients treated with PIT as outpatients. Seven patients received outpatient PIT from 2/99 to 1/05 (mean age was 14.6 years +/- 3.7). Median duration of therapy was 10 weeks (range 4-84 weeks). The mean number of emergency department visits per patient was greater before starting PIT than after starting PIT (2.3 +/- 1.8 versus 1.1 +/- 2.2, P < .05). The mean number of hospital admissions from exacerbation of heart failure symptoms decreased after starting PIT (2.1 +/- 1.3 versus 0.6 +/- 0.8, P < .05). Mean EF% in patients with systolic dysfunction improved while on therapy (30 +/- 14% before versus 39 +/- 16% after, P < .05). There was 1 death and 5 complications in 2 patients. Six patients were successfully bridged to transplantation.

CONCLUSION

Outpatient continuous parenteral inotropic therapy may serve as a successful bridge to cardiac transplantation in selected pediatric outpatients.

Outcomes Associated with Vasoactive Therapy in Patients with Acute Decompensated Heart Failure

STUDY OBJECTIVES

To describe the clinical management of acute decompensated heart failure (ADHF) in patients receiving intravenous treatment with dobutamine, milrinone, or nesiritide, and to evaluate differences, based on treatment received, in the in-hospital mortality rate, length of stay (LOS), total health care costs, and 30-day hospital readmission rate.

DESIGN

Retrospective cohort analysis.

DATA SOURCE

University HealthSystem Consortium (UHC) Clinical Database Pharmacy, a database with information from 32 academic hospitals.

PATIENTS

Two thousand one hundred thirty patients with ADHF who received dobutamine (1311 patients), milrinone (433), or nesiritide (386).

MEASUREMENTS AND MAIN RESULTS

Patients with ADHF were categorized according to the vasoactive therapy received. To evaluate baseline characteristics, chi(2) analysis was used; logistic regression was employed to assess the relationships between drug therapy and in-hospital mortality rates, and multivariate linear regression was used to assess whether drug therapy was related to LOS and total health care costs. All regression analyses controlled for age, sex, race, region of the United States where the hospital was located, primary payer for the hospital stay, UHC patient severity class, and chronic renal failure. In-hospital mortality rates were 10.2%, 7.9%, and 2.9% in the dobutamine, milrinone, and nesiritide groups, respectively. This resulted in an adjusted odds ratio for death of 3.5 (95% confidence interval [CI] 1.8-6.8) for dobutamine and 3.9 (95% CI 1.8-8.3) for milrinone (p<0.0001). Compared with inotropic therapy (dobutamine and milrinone), mean LOS in the hospital and the intensive care unit were lower with nesiritide (p<0.001). Total health care costs were lowest with nesiritide, but this reached statistical significance only when compared with milrinone (p<0.001). Thirty-day hospital readmission rates with dobutamine, milrinone, and nesiritide were 5.0%, 9.5%, and 3.9%, respectively (p=NS).

CONCLUSION

Nesiritide therapy was associated with a lower in-hospital mortality rate and shorter LOS compared with dobutamine and milrinone. In addition, total health care costs with nesiritide were decreased compared with milrinone. These observations need to be validated by a randomized controlled trial.

Flexible Versus Nonflexible Mitral Valve Rings for Congestive Heart Failure: Differential Durability of Repair

BACKGROUND

Surgical intervention is playing an increasingly important therapeutic role in congestive heart failure (CHF) patients with ischemia and dilated cardiomyopathy. Their mitral regurgitation (MR) is a result of left ventricular (LV) geometrical distortion. The optimal type of ring for CHF patients with geometric ventricular-based MR is unknown. This study reviewed the results of flexible versus nonflexible complete mitral valve rings in CHF patients with geometric mitral regurgitation.

METHODS AND RESULTS

Using a prospectively maintained database, patients undergoing mitral valve reconstruction (MVR) with either a flexible or nonflexible complete ring were identified on the basis of preoperative ejection fraction (EF) < or = 30% and no primary mitral pathology. These 2 groups of CHF patients with severe geometric MR were then compared in terms of recurrent MR requiring reoperation. Between 1992 and 2004, 289 patients with EF < or = 30%, received an undersized complete mitral annuloplasty ring as their MVR procedure. Of these, 170 patients had a flexible complete ring. In follow-up, 16 "flexible" patients (9.4%) required a repeat procedure for significant recurrent geometric MR and CHF (10 replacements, 3 re-repairs, 3 transplants). The average time to reoperation was 2.4 years. In contrast, 119 patients with an EF < or = 30% received a MVR using an undersized nonflexible complete ring. Only 3 "non-flexible" patients required a repeat operation, MVR (1), and 2 patients required a transplant. The time to reoperation was 4.0 years. A significant difference in reoperation rates, for recurrent MR, between the 2 groups (P=0.012). There were no differences between groups, in terms of age, ring size used, preoperative EF, LV size, MR grade, or New York Heart Association class.

CONCLUSIONS

Patients with CHF having a flexible ring have a higher likelihood of developing recurrent MR requiring reoperation. The use of a nonflexible ring appears to significantly reduce the need for repeat surgical procedures. Further refinement and development of nonflexible ring systems, aimed at LV restoration, deserve ongoing investigation.

Increased systemic inflammation and oxidative stress in patients with worsening congestive heart failure: improvement after short-term inotropic support

In the present study, we evaluated circulating pro-inflammatory mediators and markers of oxidative stress in patients with decompensated CHF (congestive heart failure) and assessed whether clinical recompensation by short-term inotropic therapy influences these parameters. Patients with worsening CHF (n=29, aged 61.9+/-2.7 years), NYHA (New York Heart Association) class III-IV, and left ventricular ejection fraction of 23.7+/-1.8% were studied. Controls comprised age-matched healthy volunteers (n=15; 54.1+/-3.2 years). Plasma levels of cytokines [IL (interleukin)-6 and IL-18], chemokines [MCP-1 (monocyte chemotactic protein-1)], adhesion molecules [sICAM (soluble intercellular adhesion molecule), sE-selectin (soluble E-selectin)], systemic markers of oxidation [TBARS (thiobarbituric acid-reactive substances), 8-isoprostaglandin F(2alpha) and nitrotyrosine] and hs-CRP (high-sensitivity C-reactive protein) were measured by ELISA and colorimetric assays at admission and 30 days following 72-h milrinone (n=15) or dobutamine (n=14) infusion. Plasma IL-6, IL-18, sICAM, E-selectin, hs-CRP and oxidative markers were significantly higher in patients on admission before inotropic treatment compared with controls (P<0.05). Short-term inotropic support improved clinical status as assessed by NYHA classification and by the 6-min walk test and significantly decreased plasma levels of IL-6, IL-18, sICAM, hs-CRP and markers of oxidation (P<0.05) at 30 days. The effects of milrinone and dobutamine were similar. In conclusion, our results demonstrate that patients with decompensated CHF have marked systemic inflammation and increased production of oxygen free radicals. Short-term inotropic support improves functional status and reduces indices of inflammation and oxidative stress in patients with decompensated CHF.

Levosimendan or Milrinone in the Type 2 Diabetic Patient With Low Ejection Fraction Undergoing Elective Coronary Artery Surgery

OBJECTIVES

The purpose of this study was to compare the hemodynamic profiles and the postoperative insulin requirements in 2 groups of type 2 diabetic patients with depressed myocardial function who underwent elective surgery for coronary artery disease and who received levosimendan or milrinone for postcardiopulmonary bypass low-output syndrome.

DESIGN

Randomized controlled trial.

SETTING

The Chest Diseases Hospital, Safat, Kuwait.

PARTICIPANTS

Type 2 diabetic patients undergoing elective surgery for coronary artery disease.

INTERVENTIONS

Fourteen patients and 16 patients received levosimendan and milrinone infusions, respectively, for treatment of the low-output syndrome.

MEASUREMENTS AND MAIN RESULTS

The hemodynamic, mixed venous oxygen saturation, oxygen extraction ratios, arterial lactate concentrations, and postoperative insulin infusion rates were serially documented for the first 48 hours after the diagnosis. The cardiac index and mixed venous oxygen saturation were significantly higher in the levosimendan group. The pulmonary capillary wedge pressure, systemic vascular resistance, and oxygen extraction ratios were significantly higher in the milrinone treatment group. The insulin requirements were similar for both of the treatment groups.

CONCLUSIONS

Levosimendan was more efficient than milrinone for treating the hemodynamic manifestations of the postcardiopulmonary bypass low-output syndrome. However, all the values in the milrinone treatment group were normalized. In this small population, both treatment groups had similar postoperative insulin requirements.

Dobutamine versus milrinone after subarachnoid hemorrhage

OBJECTIVE

Neurogenic stunned myocardium is a well-recognized complication of subarachnoid hemorrhage. Dobutamine and milrinone are both used for neurogenic stunned myocardium, but there are few data comparing them after subarachnoid hemorrhage.

METHODS

We compared the physiological dose response of dobutamine and milrinone in patients with subarachnoid hemorrhage requiring a pulmonary artery catheter. We located 11 patients who received either inotrope. Physiological data were fitted to a mixed model accounting for drug, dose, and between-patient variation.

RESULTS

There were 11 patients who had 152 pulmonary artery catheter measurements. Two received both inotropes (but not within 4 h of each other), 2 only milrinone, and 7 only dobutamine. The groups had similar clinical and physiological characteristics. After adjustment for vasopressin, milrinone was significantly more potent in increasing cardiac output (P <0.0001) and stroke volume (P=0.03), while decreasing vascular resistance (P <0.0001) and systolic blood pressure (P=0.008), than dobutamine.

CONCLUSION

These data suggest that milrinone and dobutamine should be used in different clinical situations. Milrinone may be more effective in patients with severely depressed systolic function but who have at least normal vascular resistance and blood pressure and in whom raising cardiac output is the primary goal. Dobutamine may be superior when vascular resistance or blood pressure is low.

Biventricular diastolic filling patterns after coronary artery bypass graft surgery

OBJECTIVE

We sought to study the evolution of biventricular filling properties after coronary artery bypass grafting.

BACKGROUND

The evolution of diastolic function as defined with newer echocardiographic modalities after coronary artery bypass grafting surgery is unknown in patients with preoperative left ventricular diastolic dysfunction.

METHODS

Transthoracic echocardiography was performed preoperatively and 48 hours and 6 months after coronary artery bypass grafting in 49 patients (randomized to milrinone [n = 25]) or placebo [n = 24]) with preoperative left ventricular diastolic dysfunction classified according to published criteria. Mild right ventricular diastolic dysfunction was defined as the ratio of early to atrial filling velocity of less than 1 in transtricuspid flow or the velocity of reversed atrial flow of greater than 50% of that of systolic flow in hepatic venous flow or the ratio of tricuspid annulus velocity during early and atrial filling of less than 1 if both the ratio of early to atrial filling velocity and the ratio of systolic to diastolic velocity was greater than 1 in hepatic venous flow. Moderate right ventricular diastolic dysfunction was diagnosed when there was a ratio of early to atrial filling velocity of greater than 1 with a ratio of systolic to diastolic velocity of less than 1. Severe right ventricular diastolic dysfunction was defined as a ratio of early to atrial filling velocity of greater than 1 associated with reversed systolic wave in hepatic venous flow.

RESULTS

Moderate and severe left ventricular diastolic dysfunction increased from preoperatively to 48 hours after coronary artery bypass grafting from 8.2% to 53.7% and from 2.0% to 9.7%, respectively (P < .0001, 48 hours vs preoperatively for both), and the patterns at 6 months were similar to those observed preoperatively. Similar evolution over time was found for right ventricular diastolic dysfunction.

CONCLUSIONS

In patients with preoperative left ventricular diastolic dysfunction, biventricular filling patterns are impaired initially but return to preoperative status 6 months after coronary artery bypass grafting.

Population Pharmacokinetics of Milrinone in Neonates with Hypoplastic Left Heart Syndrome Undergoing Stage I Reconstruction

We performed a blinded, randomized pharmacokinetic study of milrinone in 16 neonates with hypoplastic left heart undergoing stage I reconstruction to determine the impact of cardiopulmonary bypass and modified ultrafiltration on drug disposition and to define the drug exposure during a continuous IV infusion of drug postoperatively. Neonates received an initial dose of either a 100 or 250 microg/kg of milrinone into the cardiopulmonary bypass circuit at the start of rewarming. Postoperatively, milrinone was infused to clinical needs. A mixed-effect modeling approach was used to characterize milrinone pharmacokinetics during cardiopulmonary bypass, modified ultrafiltration, and postoperatively using the NONMEM algorithm. All patients in this study demonstrated a modified ultrafiltration concentrating effect that occurred despite a modified ultrafiltration drug clearance of 3.3 mL x kg(-1) x min(-1). The infants in this study demonstrated an impaired renal clearance during the immediate postoperative period. A constant infusion of 0.5 microg x kg(-1) x min(-1) resulted in drug accumulation during the initial 12 h of drug administration. Postoperatively, milrinone clearance was significantly impaired (0.4 mL x kg(-1) x min(-1)), improved by the 12th postoperative hour, and approached steady-state clearance (2.6 mL x kg(-1) x min(-1)) by postoperative day 4. In the postoperative setting of markedly impaired renal function, an infusion rate of 0.2 microg x kg(-1) x min(-1) should be considered.

Optimizing outcomes in the patient with acute decompensated heart failure

Heart failure (HF) and episodes of acute decompensated HF (ADHF) continue to pose a substantial clinical challenge in the United States and represent a significant source of morbidity, mortality, and health care resource use. Recent therapeutic advances have shifted ADHF treatment paradigms from diuretic management with or without inotrope use to therapy where intravenous vasodilators are the central component, above a background of diuretics. This shift in treatment has resulted in more rapid symptomatic improvements as well as in decreases in overall morbidity and mortality. Elevated left ventricular filling pressure has become an important clinical target for resolution during ADHF, as this parameter most closely correlates with degree of symptoms, extent of ischemic complications, and the deleterious neurohormonal activation in response to ADHF. Therapies that lead to rapid improvements in left ventricular filling pressure, including the use of nesiritide, a recombinant analog of B-type natriuretic peptide, have been shown to provide rapid symptomatic relief, but effects on long-term morbidity and mortality are as yet unclear. In addition to new treatments, new technologies--including assays based on cardiac biomarkers and techniques such as impedance cardiography for noninvasive monitoring of hemodynamic parameters--are contributing to improvements in care that will ultimately reduce the sizeable clinical and economic burden that HF represents.

Treatment with phosphodiesterase inhibitors type III and V: milrinone and sildenafil is an effective combination during thromboxane-induced acute pulmonary hypertension

OBJECTIVES

To evaluate the effects of phosphodiesterase type III and V (PDEIII and PDEV) inhibition on pulmonary and systemic haemodynamics in a porcine model of acute pulmonary hypertension.

METHODS

Twenty-four adult swine were anaesthetized with 1 MAC isoflurane and mechanically ventilated with an FI(O(2)) of 100%. Micromanometer-tipped catheters were placed in the ascending aorta, pulmonary artery and right ventricle. Pulmonary flow was measured with a perivascular probe using transit time ultrasound. Pulmonary hypertension was induced with a continuous infusion of the thromboxane analogue, U46619. The animals were then randomized to four groups: Group 1 (n=6) received 50 mg of sildenafil (PDEV inhibitor) diluted in water via an orogastric tube; Group 2 (n=6) received 50 microg kg(-1) of i.v. milrinone (PDEIII inhibitor); Group 3 (n=6) received sildenafil followed by milrinone; and Group 4 (n=6) received placebo via an orogastric tube.

RESULTS

Pulmonary hypertension was achieved in all animals. Calculated pulmonary vascular resistance decreased by an average of 36% after sildenafil (P<0.05), 41% after milrinone (P<0.05), and 61% with both drugs combined (P<0.05). Systemic vascular resistance decreased by 37% (P<0.05) with milrinone alone, and 36% (P<0.05) with milrinone and sildenafil combined but it was preserved in the sildenafil group. Cardiac output and right ventricular dP/dT were significantly improved after milrinone or both drugs combined, but not with sildenafil.

CONCLUSION

Milrinone and sildenafil are effective pulmonary vasodilators, with independent action and additive effect. Both drugs combined achieved a better haemodynamic profile, with greater pulmonary vasodilatation and increased contractility but without additional systemic vasodilatation. The systemic haemodynamic profile (systemic vasodilation, cardiac output, right ventricular dP/dT) is improved with milrinone but not with sildenafil.

Neonatal Persistent Pulmonary Hypertension Treated with Milrinone: Four Case Reports

Current standard therapy for persistent pulmonary hypertension of the newborn (PPHN) consists of optimal lung inflation, hemodynamic support and selective vasodilation with inhaled nitric oxide (iNO). However, not all infants will respond. Milrinone, a phosphodiesterase (PDE) III inhibitor, is routinely used in pediatric cardiac intensive care units to improve inotropy and reduce afterload. Although its use in post-operative cardiac failure has been proven in a randomized trial, it has not been reported to be beneficial in PPHN. We report four cases with severe PPHN treated with a combination of iNO and Milrinone. All four cases were unresponsive to therapy including iNO, with a mean oxygenation index (OI) of 40 (standard deviation (SD) 12)) before Milrinone. Substantial improvement in OI (mean of 28; SD 16) was followed by extubation and survival. However, of 4 patients, 2 developed serious intraventricular hemorrhages (IVHs), and 1 had a small IVH. To clarify the risk benefit ratio, of death versus survival with impairment, a randomized controlled trial is needed.

The Effects of Olprinone, a Phosphodiesterase 3 Inhibitor, on Systemic and Cerebral Circulation

Olprinone, a phosphodiesterase (PDE) 3 inhibitor, is used to treat heart failure due to its positive inotropic and vasodilative effects. Selective inhibition of the PDE 3 isozyme increases intracellular adenosine 3;5;-cyclic monophosphate and enhances Ca(2+) influx into cardiac muscle cells. The most significant advantage of PDE 3 inhibitors is their ability not only to enhance myocardial contraction, but to reduce, through vasodilatory action, the stress to which the heart is subjected. In peripheral vessels, the decrease of cytosolic free Ca(2+) induces the vasorelaxation of vascular smooth muscle cells. In this way, olprinone reduces mean aortic and pulmonary artery pressures. Additionally, olprinone exerts differential vasodilatory effects on peripheral vessels in each organ, based on the differences in the distribution of PDE 3 among the organs. With respect to the cerebral circulation, olprinone augments blood flow in the cerebral cortex through direct vasodilatory effects on small cerebral arteries or arterioles. Olprinone increases hepatosplanchnic blood flow and improves oxygen supply. While long-term therapy with PDE 3 inhibitors in patients with chronic heart failure may accelerate the progress of the underlying disease and provoke serious ventricular arrhythmia, olprinone shows good potential for short-term treatment in patients who have experienced severe heart failure or patients who have undergone cardiac surgery.

NT-proBNP as a marker for persistent cardiac disease in children with history of dilated cardiomyopathy and myocarditis

Children with myocarditis and dilated cardiomyopathy may recover clinically and echocardiographically. Plasma levels of the N-terminal segment of B-type natriuretic peptide prohormone (NT-proBNP), a sensitive marker for cardiac dysfunction, may reflect residual cardiac damage in these patients. The purpose of this study was to evaluate NT-proBNP status in pediatric patients with a history of myocarditis and dilated cardiomyopathy. Cardiac evaluation was performed and the levels of NT-proBNP were measured in 23 children who had a history of myocarditis or dilated cardiomyopathy. NT-proBNP levels were also measured in 56 age-matched control children. Nine of the 23 patients had evidence of left ventricular dysfunction (DCM group), whereas 14 had none (recovery). NT-proBNP levels were higher in the DCM group (3154 +/- 2858 pg/ml) than in the recovery group (122 +/- 75 pg/ml, p < 0.001) and the control group (113 +/- 96 pg/ml, p < 0.001). There was no difference between the recovery and the control groups (p = 0.45), and none of the recovered patients had a NT-proBNP level higher than the upper limit of normal. The area under the receiver operating characteristics curve for the diagnosis of persistent left ventricular dysfunction was 0.984. NT-proBNP levels correlated with echocardiographically derived shortening fraction and with clinical score. NT-proBNP is a good marker for persistent left ventricular dysfunction in children who have had myocarditis or cardiomyopathy. In this group of patients, NT-proBNP levels are normal in children who recover echocardiographically, suggesting no residual hemodynamic abnormalities.