Prostaglandin E1--bridge to cardiac transplantation. Technique, dosage, results

Prostaglandin E1 attenuates AngII-induced cardiac hypertrophy via EP3 receptor activation and Netrin-1upregulation

AIMS

Pathological cardiac hypertrophy induced by activation of the renin-angiotensin-aldosterone system (RAAS) is one of the leading causes of heart failure. However, in current clinical practice, the strategy for targeting the RAAS is not sufficient to reverse hypertrophy. Here, we investigated the effect of prostaglandin E1 (PGE1) on angiotensin II (AngII)-induced cardiac hypertrophy and potential molecular mechanisms underlying the effect.

METHODS AND RESULTS

Adult male C57 mice were continuously infused with AngII or saline and treated daily with PGE1 or vehicle for two weeks. Neonatal rat cardiomyocytes were cultured to detect AngII-induced hypertrophic responses. We found that PGE1 ameliorated AngII-induced cardiac hypertrophy both in vivo and in vitro. The RNA sequencing (RNA-seq) and expression pattern analysis results suggest that Netrin-1 (Ntn1) is the specific target gene of PGE1. The protective effect of PGE1 was eliminated after knockdown of Ntn1. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the PGE1-mediated signaling pathway changes are associated with the mitogen-activated protein kinase (MAPK) pathway. PGE1 suppressed AngII-induced activation of the MAPK signaling pathway, and such an effect was attenuated by Ntn1 knockdown. Blockade of MAPK signaling rescued the phenotype of cardiomyocytes caused by Ntn1 knockdown, indicating that MAPK signaling may act as the downstream effector of Ntn1. Furthermore, inhibition of the E-prostanoid (EP) 3 receptor, as opposed to the EP1, EP2, or EP4 receptor, in cardiomyocytes reversed the effect of PGE1, and activation of EP3 by sulprostone, a specific agonist, mimicked the effect of PGE1.

CONCLUSION

In conclusion, PGE1 ameliorates AngII-induced cardiac hypertrophy through activation of the EP3 receptor and upregulation of Ntn1, which inhibits the downstream MAPK signaling pathway. Thus, targeting EP3, as well as the Ntn1-MAPK axis, may represent a novel approach for treating pathological cardiac hypertrophy.

Outcome of conservative management vs. assist device implantation in patients with advanced refractory heart failure

BACKGROUND

In patients with advanced refractory heart failure (HF) cardiac transplantation (HTX), conservative medical management and the implantation of a ventricular assist device (VAD) represent valuable options. The determination of the best therapeutic destination strategy for the individual patient remains a challenge. The aim of this study was to assess the clinical outcome in advanced refractory HF patients either managed conservatively receiving optimal contemporary medical therapy ('conservative'), or who who underwent pulsatile flow VAD ('pVAD') or continuous-flow VAD ('contVAD') implantation.

MATERIALS AND METHODS

A total of 118 patients with INTERMACS profile >1 at baseline, who died, or fully completed a 24-month follow-up free from HTX were included into this retrospective analysis. All-cause mortality at 24 months was assessed and compared between the three groups.

RESULTS

Fifty (42%) patients were managed conservatively, 25 (21%) received a pVAD and 43 (36%) a contVAD. NT-proBNP values were comparable between the three groups (median 4402 (IQR 2730-13390) pg/mL, 3580 (1602-6312) pg/mL and 3693 (2679-8065) pg/mL, P = 0·256). Mean survival was 18·6 (95% CI 16·2-21·0) months for patients managed conservatively, 7·0 (3·9-10·0) for pVAD and 20·5 (18·2-22·8) for contVAD (overall log-rank test P < 0·001). Conservatively managed patients spent a mean of 22·4 (95% CI 22·1-22·8), pVAD 17·7 (15·4-20·1) and contVAD 21·6 (21·2-22·1) months out of hospital (conservative vs. pVAD P < 0·001; conservative vs. contVAD P = 0·015; pVAD vs. contVAD P < 0·001).

CONCLUSIONS

In accordance with the literature, contVAD resulted in a significantly better clinical outcome than pVAD implantation. However, conservative management with current optimal medical therapy appears to remain a valuable option for patients with advanced HF.

Study of molecular mechanism of Prostaglandin E1 in inhibiting coronary heart disease

Prostaglandin E1 has been used clinically for improving heart diseases. In this study, we examined the effect of Prostaglandin E1 on blood lipid levels, heart protein and genes expression in coronary heart disease (CHD) rats. Female rats were fed either a control diet or hypercholesterolemic diet for 14 weeks. The feeding of a hypercholesterolemic diet (HCD) increased the serum TC, TG, and LDL-c levels, decreased the serum HDL-c, E2, P, FSH, LH and PRL levels in CHD rats. In addition, The feeding of a HCD diet markedly increased the content of serum TXA2, TXB2, and decreased the content of serum PGI2, and PGI2/TXA2, 6-Keto PGF1a. Furthermore, the feeding of a hypercholesterolemic diet markedly increased expression levels of myocardium Fas and Caspase-3 protein and mRNA levels, vascular endothelial growth factor and basic fibroblast growth factor mRNA, and decreased RyR2 mRNA in CHD rats. The feeding of Prostaglandin E1 for 14 weeks significantly reversed these abnormal biochemical indexes in rats. These findings suggest that Prostaglandin E1 play a obvious heart protective effect. The mechanisms may be related to restraining the excessive activation of Fas and Caspase-3 protein and modulating some gene expressions associated with CHD.

Benefit of prostaglandin infusion in severe heart failure: preliminary clinical experience of repetitive administration

BACKGROUND

Prostaglandin E1 (PGE1) is a potent vasodilating drug, which has been used in treatment of primary pulmonary hypertension. However intravenous PGE1 infusion may be of benefit and also has been proposed as a therapeutic tool in patients with end-stage heart failure. The aim of this prospective not randomized study was to assess the clinical and instrumental effects of this agent in patients with severe heart failure and pulmonary hypertension.

METHODS

To investigate the effects of PGE1 in congestive heart failure we selected 22 consecutive patients (16 males, 6 females, mean age 63±2 years) in the mean NYHA class III, because they had pulmonary hypertension (PAPs>3 m/s and left ventricular ejection fraction (LVEF) ≤35% by echocardiography. A control group of 23 patients (19M, 4F mean age 62±5 years; 9 patients were in the NYHA class IV and 14 in the NYHA class III), with the same instrumental and clinical data, received an optimized oral treatment with beta-blockers, ACE-inhibitors, furosemide and digitalis. Right heart catheterization was performed to confirm and determine the type of pulmonary hypertension, before starting the PGE1 infusion. Clinical and echocardiography evaluation was performed during follow-up. PGE1 was infused at a mean dose of 10 ng/kg/min for a total of 24 h over three consecutive days every three months.

RESULTS

Right heart catheterization confirmed a high systolic pulmonary pressure in all patients; pre-capillary pulmonary hypertension (mean PAP>25 mm/Hg) was 25%. During a mean follow-up of 36±6 months, 16 patients died (10 in the control group and 6 in the PGE1 group). The Kaplan-Meier 3-years survival analysis was not statistically significant (Log-rank test), but at 2 months survival rates began to diverge; 36 months survival: 72.7% in the PGE1 group and 56% in the control group. The mean LVEF increased from 25.78% to 32.1% in the PGE1 group and from 23.38% to 26.15 in the control group (p<0.001); the NYHA mean class improved from 3.18 to 2.24 in the PGE1 group and from 3.46 to 3.38 in the control group (p<0.05). The PAP decreased from 57.65 to 40.82 mm/Hg (p<0.001). An AICD was implanted in 3 patients in the first group and in 5 patients in the control group. Two patients were added to the heart transplantation list.

CONCLUSION

These preliminary data suggest that intermittent PGE1 infusion in patients with advanced congestive heart failure and high pulmonary pressure is able to improve NYHA mean class (p<0.05), ventricular contractility (LVEF p<0.001), pulmonary pressure and clinical data. It hasn't been associated to morbid events or increased risk of death.

Short-term effects of levosimendan and prostaglandin E1 on hemodynamic parameters and B-type natriuretic peptide levels in patients with decompensated chronic heart failure

BACKGROUND

Both levosimendan and prostaglandin E1 (PGE1) have beneficial effects on hemodynamic parameters and outcome compared to dobutamine in decompensated chronic heart failure (CHF).

AIMS

We compared short-term effects of levosimendan versus PGE1 on hemodynamic parameters and B-type natriuretic peptide levels (BNP) in patients with decompensated CHF.

METHODS AND RESULTS

73 patients (cardiac index < 2.5 L/min/m2, pulmonary capillary wedge pressure (PCP) >15 mmHg) with decompensated CHF were randomised to treatment with either a 24 h-infusion of levosimendan (n=38) or a chronic infusion of PGE1 (n = 35). Hemodynamic parameters and BNP were measured at baseline, 24 and 48 h, BNP levels were also measured after 1 week. Baseline characteristics including concomitant medication were similar in both groups. Levosimendan and PGE1 increased cardiac output (CO) after 24 and 48 h. Levosimendan increased CO twice as much as PGE1 (24 h: Levosimendan +1.1 +/- 0.1 L/min, PGE1 +0.6 +/- 0.1 L/min, p < 0.001). Both drugs produced a comparable reduction in PCP and pulmonary artery pressure after 24 and 48 h. Levosimendan decreased BNP by 28% after 24 h and 22% after 48 h, but effects disappeared after 1 week. In contrast, PGE1 decreased BNP by 15% after 48 h (no change at 24 h), but a decrease of 20% was sustained at 1 week.

CONCLUSIONS

The differential beneficial effects of levosimendan (greater increase in CO) and PGE1 (sustained decrease in BNP) may have a potential impact on clinical outcome.

PGE1analog alprostadil induces VEGF and eNOS expression in endothelial cells

Endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor 1-α (HIF-1α) are important regulators of endothelial function, which plays a role in the pathophysiology of heart failure (HF). PGE1analog treatment in patients with HF elicits beneficial hemodynamic effects, but the precise mechanisms have not been investigated. We have investigated the effects of the PGE1analog alprostadil on eNOS, VEGF, and HIF-1α expression in human umbilical vein endothelial cells (HUVEC) using RT-PCR and immunoblotting under normoxic and hypoxic conditions. In addition, we studied protein expression by immunohistochemical staining in explanted hearts from patients with end-stage HF, treated or untreated with systemic alprostadil. Alprostadil causes an upregulation of eNOS and VEGF protein and mRNA expression in HUVEC and decreases HIF-1α. Hypoxia potently increased eNOS, VEGF, and HIF-1α synthesis. The alprostadil-induced upregulation of eNOS and VEGF was prevented by inhibition of MAPKs with PD-98056 or U-0126. Consistently, the expression of eNOS and VEGF was increased, and HIF-1α was reduced in failing hearts treated with alprostadil. The potent effects of alprostadil on endothelial VEGF and eNOS synthesis may be useful for patients with HF where endothelial dysfunction is involved in the disease process.

Nitric Oxide Versus Prostaglandin E1 for Reduction of Pulmonary Hypertension in Heart Transplant Candidates

BACKGROUND

We sought to directly compare the effects of prostaglandin E1 (PGE1) and nitric oxide (NO) in testing for pulmonary hypertension reversibility in heart transplant candidates.

METHODS

We included 19 heart transplant candidates who fulfilled at least 1 of 3 criteria: pulmonary vascular resistance (PVR) of >4 Wood units; transpulmonary gradient (TPG) of >12 mmHg; or systolic pulmonary artery pressure (PAP) of >60 mmHg. Patients randomly received either PGE1 (0.05, 0.2 and 0.5 microg/kg/min) or NO (40, 60 and 80 ppm) and were crossed-over to the second medication after receiving the maximal dose of the first.

RESULTS

With PGE1, TPG decreased by 21% (baseline 20.3 +/- 6.8 mmHg; final 16.0 +/- 7.0 mmHg) compared to a 34% decrease with NO (baseline 20.8 +/- 6.2 mmHg; final 13.8 +/- 5.4 mmHg) (p = 0.13). PVR decreased by 42% with PGE1 (baseline 6.2 +/- 4.0 Wood units; final 3.6 +/- 1.8 Wood units) and by 47% with NO (baseline 6.0 +/- 3.9 Wood units; final 3.2 +/- 1.6 Wood units) (p = 0.87). Mean systemic pressure decreased with PGE1 (baseline 76.1 +/- 10.5 mmHg; final 69.4 +/- 12.2 mmHg; -9%) but not with NO administration (baseline 70.2 +/- 14.7 mmHg; final 71.6 +/- 10.9 mmHg; +2%) (p = 0.01). TPG was lowered to <12 mmHg in 14 patients. Of these, 6 (46%) responded to both PGE1 and NO, 4 (27%) responded only to PGE1, and 4 (27%) responded only to NO.

CONCLUSIONS

The effects of PGE1 and NO on pulmonary hypertension are comparable, with PGE1 having more systemic hypotensive effects. Due to variability of patient responses, we recommend multiple rather than single-agent pharmacologic testing for the reversibility of pulmonary hypertension.

Revascularization of myocardial scar tissue following prostaglandin E1-therapy in patients with ischemic heart disease

Prostaglandin E1 (PGE-1) treatment has proved to stimulate angiogenesis in vital non-infarcted myocardium of patients with ischemic cardiomyopathy (ICMP). We investigated infarcted myocardial tissue for a possible angiogenic response to PGE-1. Neovascularization was investigated in infarcted areas of 12 hearts explanted from patients with ICMP who had been treated with PGE-1 before heart transplantation (HTX). In transmural sections containing myocardial scar tissue, CD34 and VEGF were immunohistochemically quantified to estimate capillary density and the extent of angiogenesis. To investigate a possible effect of PGE-1 on collagen turnover, the collagen content was determined in myocardial scar tissue by assessing the intensity of the area positively stained with sirius red. PGE-1-treated patients had significantly more CD34- and VEGF-positive cells in infarcted areas, and showed a significant reduction in collagen content as compared with the non-PGE-1 group (CD34: 120.3 +/- 6.1 vs. 47.7 +/- 6.1 capillary profiles/mm2; VEGF: 52.8 +/- 5.6 vs. 24.0 +/- 4.8 capillary profiles/mm2, and collagen content: 2.18 +/- 0.4 eU vs. 3.59 +/- 0.38 eU). Our data demonstrate that PGE-1 stimulates angiogenesis by upregulating VEGF expression, and reduces fibrosis in cardiac scar tissue of ischemic origin. The induction of therapeutic angiogenesis in vital and at sites of putative dead myocardial scar tissue, along with the hemodynamic improvement in patients with severe ICMP, might explain the favorable clinical outcome in PGE-1-treated patients before HTX.

Reversible pulmonary hypertension in heart transplant candidates-pretransplant evaluation and outcome after orthotopic heart transplantation

BACKGROUND

Heart transplantation is the most effective treatment for well-selected patients with endstage heart failure. Unfortunately, transplant candidates with pulmonary hypertension (PHT) are often not considered for heart transplantation. This study was performed to assess the value of prostaglandin E(1) (PG-E(1)) for reduction of PHT and to predict the postoperative outcome, compared to patients without PHT.

PATIENTS AND METHODS

We studied a group of 151 consecutive heart transplant candidates using right heart catheterization. In patients with PHT (pulmonary vascular resistance, PVR> or =2.5 Wood-Units (WU) and/or transpulmonary gradient (TPG)> or =12 mmHg) a short-term treatment protocol with PG-E(1) was performed, to achieve PVR<2.5 WU and TPG<12 mmHg.

RESULTS

61 patients (40%) had PHT according to our criteria. Reduction of PHT was successful in 71% of patients (n=43), of these, 18 patients underwent cardiac transplantation and the 1-year mortality rate was 22% (n=4). The 1-year mortality rate in transplanted patients without PHT was 14% (n=3). There was no statistical difference in survival between the PHT and the non-PHT group. Outcome in patients without heart transplantation was similar in both groups, except for patients with non-reducible PHT (1-year mortality 50%).

CONCLUSIONS

Our study demonstrates the efficacy and safety of PG-E(1) in lowering PHT in heart transplant candidates, as well as the need for aggressive evaluation and treatment in these patients. Patients with reversible PHT have comparable post-transplant outcomes and no tendency to higher acute right ventricular failure.

Sequential big endothelin plasma levels in heart transplant recipients during bridging therapy and after successful heart transplantation

BACKGROUND

The purpose of this study was to investigate the impact of successful heart transplantation in patients with refractory heart failure receiving bridging therapy on sequential plasma levels of big endothelin, norepinephrine, atrial natriuretic peptide and aldosterone.

METHODS

Fourteen patients (2 women, 12 men) accepted for heart transplantation were studied. All had severe chronic heart failure refractory to optimized oral therapy with angiotensin-converting enzyme inhibitors and furosemide, were in New York Heart Association functional Class IV, and had a left ventricular ejection fraction of <15%, Right heart catheterization was performed in all patients (cardiac index 1.9 +/- 0.1 liters/min. m(2), pulmonary capillary wedge pressure 30 +/- 2 mmHg, systemic vascular resistance index 2,827 +/- 253 dyn. s/cm(5). m(2)). As bridging therapy, patients received either prostaglandin E(1), prostaglandin E(1) and dobutamine or dobutamine alone as a continuous infusion. Neurohumoral variables were measured prior to bridging therapy and 3.5 months before and 7 and 10 months after successful heart transplantation.

RESULTS

Big endothelin, norepinephrine and atrial natriuretic peptide plasma levels decreased from 7.4 +/- 2.9 fmol/ml, 1112 +/- 686 pg/ml and 366 +/- 312 pg/ml to 6.0 +/- 4.5 fmol/ml, 720 +/- 503 pg/ml and 198 +/- 160 pg/ml, respectively, after bridging therapy, and further to 2.1 +/- 0.9 fmol/ml (p < 0.00001 vs baseline), 527 +/- 31 pg/ml (p < 0.02 vs baseline) and 115 +/- 70 pg/ml (p < 0.03 vs baseline), respectively, after cardiac transplantation. Aldosterone plasma levels decreased from 242 +/- 220 pg/ml to 183 +/- 142 pg/ml during bridging therapy and increased after heart transplantation to 252 +/- 189 pg/ml. Plasma creatinine levels increased from 1.2 +/- 0.4 mg/dl at baseline to 1.4 +/- 0.2 mg/dl after transplantation (NS).

CONCLUSIONS

The study suggests that excessive overproduction of big endothelin, atrial natriuretic peptide and norepinephrine is predominantly related to pump failure and, after cardiac transplantation, a moderate spillover of big endothelin persists. Its specific origin, however, remains to be elucidated. Furthermore, our data suggest a protective effect of prostaglandin E(1) on kidney function after heart transplantation.

Clinical benefit of prostaglandin E1-treatment of patients with ischemic heart disease: stimulation of therapeutic angiogenesis in vital and infarcted myocardium

New evidence suggests that Prostaglandin E1 (PGE-1) stimulates myocardial angiogenesis in human chronic ischemic myocardium. We sought to investigate whether PGE-1 may participate in the process of neoangiogenesis within the myocardial infarct scar. Neovascularization was investigated in 14 explanted hearts from patients with ischemic cardiomyopathy, who had been bridged to heart transplantation (HTX) with PGE-1 and compared with 14 hearts from patients who did not receive PGE-1 prior to HTX. In transmural sections obtained from the left ventricular wall and containing myocardial scar tissue, CD34 and vascular endothelial growth factor (VEGF) were quantified immunohistochemically to estimate capillary density and amount of angiogenesis. Additionally, to assess the hypoxic state of myocardium of the infarct border zone, hypoxia inducible factor 1-alpha (HIF-1alpha) was determined by immunohistochemistry and quantified by means of planimetric analysis. PGE-1-treated patients had significantly more CD34-and VEGF-positive cells in infarct areas as compared to nonPGE-1 group, respectively (CD34: 116.7 +/- 5.9 vs. 45.1 +/- 5.2 capillary profiles/mm(2), P < 0.001, and VEGF: 48.3 +/- 4.9 vs. 22.9 +/- 4.7 capillary profiles/mm(2)). HIF-1alpha enrichment (in %) as well as staining intensity (in estimated units (eU)) was significantly decreased in PGE-1-treated as compared to non-treated controls (enrichment: 11.3 +/- 2.5% vs. 19.4 +/- 4.36%; staining intensity: 0.95 +/- 0.3 vs. 1.97 +/- 0.44 eU). Our data demonstrate that PGE-1 stimulates neoangiogenesis in infarct areas adjacent to viable myocardium, via upregulation of VEGF expression. The induction of therapeutic angiogenesis along with the improved hypoxic state of chronic ischemic myocardial tissue might explain the favorable clinical outcome in PGE-1 treated patients.

Angiogenesis stimulation in explanted hearts from patients pre-treated with intravenous prostaglandin E(1)

BACKGROUND

Prostaglandin E(1) (PGE(1)) is a potent vasodilator and induces angiogenesis in animal tissues. Previous clinical studies demonstrated that PGE(1) improves hemodynamic parameters in patients with heart failure listed for heart transplantation (HTX). Therefore, we designed a retrospective immunohistochemistry study to investigate various markers of angiogenesis using hearts explanted from PGE(1)-treated patients with idiopathic dilated cardiomyopathy (IDCM).

METHODS AND RESULTS

We investigated neovascularization in 18 hearts explanted from patients with IDCM: 9 patients received treatment with chronic infusions of PGE(1) for end-stage heart failure before HTX, whereas the remaining patients with IDCM did not receive PGE(1) and served as controls. We used immunoreactivity against CD34, von Willebrand factor (vWf), vascular endothelial growth factor (VEGF), and MIB-1 (Ki-67) to quantify angiogenesis, and used sirius red staining to determine the degree of fibrosis. Compared with the control group, PGE(1)-treated patients had significantly more CD34-, vWf- and MIB-1-positive cells in the sub-endocardium, myocardium and sub-epicardium (p < 0.01). The degree of fibrosis in the hearts of PGE(1)-treated patients was significantly lower than in control patients (p < 0.05), but we did not see any difference in the percentage of muscle mass. Finally, throughout the ventricles, we found significantly more VEGF-positive capillaries in the PGE(1) group (p < 0.0001).

CONCLUSIONS

The data suggest that PGE(1) could be a potent inducer of angiogenesis and the angiogenic factor VEGF, and could cause reduced fibrosis in the failing human heart.

Response of right ventricular function to prostaglandin E1 infusion predicts outcome for severe chronic heart failure patients awaiting urgent transplantation

BACKGROUND

Selection of patients for urgent heart transplantation who have end-stage heart failure requires objective criteria to distinguish between subjects who may deteriorate clinically and those who can be stabilized. This population appears to differ in terms of right ventricular function, and right ventricular changes in loading may provide prognostic information. To investigate predictive parameters of patients admitted for urgent heart transplantation, we prospectively studied the mechanical performance of the right ventricle during acute afterload reduction.

PATIENTS AND METHODS

We studied 68 heart failure patients hospitalized for bridge-to-transplant. The patients underwent right heart catherization at baseline and during prostaglandin E1 infusion. We stratified patients according to clinical outcome: Group A comprised patients who could be weaned from bridging therapy or who were electively transplanted after at least 90 days, and Group B comprised patients who died or who remained unstable and required transplant under urgent conditions.

RESULTS

Right ventricular hemodynamics at baseline were comparable in both groups. However, during maximal vasodilatation, with prostaglandin E1 infusion, the right ventricular end-diastolic volume index (EDVI) was significantly reduced in Group A, (-23 ml/m(2) (p < 0.01) vs +12 ml/m(2) (p = n.s. DeltaEDVI in Group B. Reduction of EDVI by less than 10% during prostaglandin E1 infusion has a sensitivity of 89% and a specificity of 70% for clinical deterioration.

CONCLUSIONS

The response of right ventricular volumes to prostaglandin E1 may predict the outcome of patients with severe congestive heart failure listed for urgent heart transplantation.

Prostaglandin E(1) does not influence plasmatic coagulation, hepatic synthesis, or postoperative blood loss in patients after coronary-artery bypass grafting

STUDY OBJECTIVE

To assess whether postoperatively administered prostaglandin E1 (PGE1) might prevent bleeding in patients after coronary artery bypass grafting (CABG).

DESIGN

Prospective, randomized, placebo-controlled trial.

SETTING

University-affiliated hospital.

PATIENTS

49 patients scheduled for elective CABG surgery.

INTERVENTIONS

The PGE1 group received intravenous PGE(1) up to 15 ng/kg/min for 72 hours after surgery, whereas the placebo group received isotonic saline for the same time period.

MEASUREMENTS AND MAIN RESULTS

Nine patients (4 in the PGE1 group vs. 5 in the placebo group) had to be excluded because of hemodynamic instability, and 1 in the placebo group because of gastric bleeding. In the remaining 39 patients (20 vs. 19), no significant differences with regard to hemoglobin levels or platelet count could be observed. There was no significant difference between the groups concerning the amount of packed red blood cells, platelet concentrates, or fresh frozen plasma transfused. No significant differences could be observed regarding laboratory markers of coagulation activation or hepatic synthesis either.

CONCLUSIONS

PGE1 did not prevent coagulation disturbances and blood loss when administered postoperatively in patients undergoing CABG. The absence of these expected effects might be explained by the concomitant administration of acetylsalicylic acid, whose antiaggregatory acivity seems to exceed the effects of PGE1.

Effects of prostaglandin E1, dobutamine and placebo on hemodynamic, renal and neurohumoral variables in patients with advanced heart failure

Excessive neurohumoral activity remains a major burden to the circulation of patients with advanced heart failure. Prostaglandin E1 (PGE1), a balanced i.v. vasodilator, was shown to elicit favorable hemodynamic and clinical effects in this cohort. A prospective randomized parallel group trial was performed to evaluate acute, intermediate and chronic changes in hemodynamic, neurohumoral and renal variables in response to PGE1, dobutamine and placebo. Thirty patients with class III and IV heart failure and low cardiac index (mean 1.9 l/min/m2) two hours after oral drugs including high dose enalapril were included. A 7-day-infusion of PGE1 (16.5 +/- 5 ng/kg/min, range 10 to 20 ng/kg/min, group A n = 10), dobutamine (4.5 +/- 1 micrograms/kg/min, range 2.5 to 5 micrograms/kg/min, group B n = 10) or placebo (saline, group C n = 10) was administered via a central venous access line after stepwise titration until intolerable side effects developed with PGE1 or a 20% increase in cardiac index occurred with dobutamine, which was continued on this dose throughout while PGE1 was maintained on 50% peak dose. Hemodynamic data were collected at baseline, at peak dosages, after 12 hours and after 7 days. Of neurohumoral variables plasma norepinephrine, big endothelin (Big ET) and atrial natriuretic peptide (ANP) were simultaneously evaluated using RIA methods. Renal plasma flow (by paraaminohippurate clearance) and glomerular filtration rate (by iothalamate clearance) was measured prior to and during the infusions (after 12 hours and after 7 days). At peak dose and at 12 hours significant drops from baseline of mean pulmonary artery pressure, pulmonary capillary wedge pressure and systemic vascular resistance were observed which were accompanied by a rise in cardiac output with both PGE1 and dobutamine. These changes were maintained through 7 days when pulmonary vascular resistance levels also fell with both active drugs. Blood pressure did not change throughout, but PGE1 increased heart rate slightly at 12 hrs. Both PGE1 and dobutamine enhanced renal plasma flow after 7 days, but only PGE1 decreased glomerular filtration fraction significantly. Glomerular filtration rate did not change with either drug. PGE1 decreased ANP levels at 12 hrs, and dobutamine increased big ET levels at peak, but decreased big ET at 7 days. Norepinephrine levels were unaffected throughout. Except a slight decrease in right atrial pressure after 7 days placebo did not change any measured variable significantly. Taken together, these data suggest that treatment with PGE1 is as efficacious as low-dose dobutamine in improving cardiac performance and renal perfusion in advanced heart failure. Of importance, no deleterious neurohumoral counterregulation was observed with PGE1.

Bridging to heart transplantation: prostaglandin E1 versus prostacyclin versus dobutamine

BACKGROUND

Prostaglandin E1 (PGE1) and prostacyclin have potent pulmonary and systemic vasodilating properties. This prospective, randomized trial compared PGE1 vs prostacyclin vs. low-dose dobutamine in patients with low-output heart failure awaiting heart transplantation (HTx) who were refractory to oral treatment.

METHODS

Patients in advanced heart failure in New York Heart Association (NYHA) Class IV, with a cardiac index < or = 2.5 L/minute/m2 and a pulmonary capillary wedge pressure > or = 20 mmHg, who were listed for HTx were studied. In an inpatient study phase of 12 hours duration, therapy was aimed to increase cardiac output by 20% or more, when compared to baseline values, and to achieve a reduction of pulmonary vascular resistance below 550 dyn.s/cm-5m-2. During a long-term outpatient phase, the drugs were continuously infused to bridge these patients to HTx using three combined negative endpoints (worsening heart failure, serious adverse events, death) for analysis.

RESULTS

Sixty-eight patients were enrolled, 30 patients on PGE1, 8 patients on prostacyclin, and 30 patients on dobutamine. During the inpatient study phase, maximum doses were 22 +/- 1.8 ng/kg/minute for PGE1, 7 +/- 1 ng/kg/minute for prostacyclin and 5 +/- 0.4 micrograms/kg/minute for dobutamine. During the inpatient study phase 21 patients failed, 4/30 (13%) patients on PGE1, 4/8 patients on prostacyclin (50%), and 13/30 (43%) on dobutamine (p < 0.05). Long-term continuous intravenous drug infusion in outpatients was begun in 26 patients on PGE1, in 4 patients on prostacyclin, and in 17 patients on dobutamine. Infusion therapy lasted for 88 +/- 14 days in the PGE1 group with 31 +/- 22 days in the prostacyclin group, and 30 +/- 8 days in the dobutamine group (NS). During the outpatient phase 23 patients reached a negative endpoint with 16 patients developing worsening heart failure, 5 severe adverse events and 2 deaths. Seven out of 26 (27%) failed on PGE1, 4/4 (100%) failed on prostacyclin, and 12/17 (71%) failed on dobutamine (p < 0.05, log rank test). Because prostacyclin treatment was ineffective in the first 8 patients, this trial arm was stopped prematurely.

CONCLUSIONS

The findings from this prospective open pilot trial suggest that continuous PGE1 infusions at individualized dosages can be useful in certain patients as a pharmacologic bridging procedure with reduced risk to develop worsening heart failure before HTx compared to prostacyclin and dobutamine. Further comparative studies are warranted to investigate the effects of PGE1 among other bridging agents.

The implantable cardioverter defibrillator as a "bridge to transplant": a viable clinical strategy?

Heart transplantation is an accepted therapeutic option for patients with end-stage heart disease. However, because the availability of heart donors fails to keep pace with the growing demand, increasing numbers of potential recipients are placed on the waiting list, resulting in longer waiting times. About 20% of patients die while awaiting heart transplantation. The majority die from progressive pump failure (46%), whereas about 30% of all deaths occur suddenly. Monitored terminal cardiac electrical activity in patients dying while awaiting transplantation reveals that bradyarrhythmias and/or electromechanical dissociation are involved in 68% of cases and ventricular tachyarrhythmias in 32% of cases. Patients with a history of aborted cardiac arrest are at highest risk for recurrent malignant arrhythmias. The implantable cardioverter defibrillator (ICD) is the most effective therapy for preventing sudden cardiac death from ventricular tachyarrhythmias. Pooled data from a total of 75 sudden death survivors listed for cardiac transplantation demonstrate that ICD therapy can be applied with low mortality, low morbidity, and high efficacy, with up to 94% of the patients receiving appropriate shocks during the waiting period. However, there is considerable concern that this early survival benefit conferred by the ICD may be nullified by the competing risk of death due to terminal pump failure, as the waiting list and waiting time to transplantation lengthens. In advanced heart failure, risk stratification for sudden tachyarrhythmic death is only of limited value. Therefore, although sudden tachyarrhythmic death appears to constitute only a minor fraction of total cardiac death in patients awaiting heart transplantation, prophylactic ICD implantation as on electronic bridge to transplant may be considered. To define conclusively the role of prophylactic ICD therapy in this setting, prospective randomized studies are needed.

Effect of prostaglandin E1 infusion in severe chronic heart failure

Prostaglandin E1 (PGE1, alprostadil) is a potent vasodilating agent that is frequently used to resolve cardiogenic pulmonary hypertension. To investigate the effect of PGE1 in refractory chronic heart failure in a double-blind trial, twenty patients (17 men, 3 women, 58 +/- 2 years, cardiac index < or = 2.5 l/min/m2, pulmonary capillary wedge pressure > or = 20 mmHg), who were in NYHA functional class IV on optimized treatment with ACE inhibitors and furosemide were infused with 30 ng/kg/min PGE1 or placebo through 48 hours. All patients received a concomitant therapy with standardized catecholamine infusions which were given 24 hours in advance and were continued throughout the study. There was no difference in baseline values between the randomized groups before PGE1 or placebo was added. PGE1 resulted in decrements in pulmonary artery pressure (from 37 +/- 4 to 30 +/- 4 mmHg; p < 0.01), pulmonary capillary wedge pressure (from 26 +/- 4 to 19 +/- 3 mmHg p < 0.001) systemic vascular resistance index (from 2048 +/- 213 to 1506 +/- 13 dyn.sec/cm5.m2, p < 0.05) and in increments in cardiac index and stroke volume index (from 2.2 +/- 0.1 to 2.8 +/- 0.2 l/min.m2; p < 0.05 and from 23 +/- 2 to 28 +/- 2 l/m2; p < 0.05, respectively). Moreover, creatinine clearance increased (p < 0.05). Placebo infusions did not result in any hemodynamic or renal effect. Between groups percentage hemodynamic changes differed with respect to pulmonary artery pressure (p < 0.01), cardiac index (p < 0.05), stroke volume index (p < 0.05) and pulmonary vascular resistance index (p < 0.05). It is concluded that intravenous infusions with PGE1 may add further substantial benefit to the hemodynamic state in refractory heart failure patients who are already stabilized on i.v. inotropic support with catecholamines.