Acute hemodynamic effects of intravenous sildenafil citrate in congestive heart failure: comparison of phosphodiesterase type-3 and -5 inhibition

An Update on Pharmacologic Management of Neonatal Hypotension: When, Why, and Which Medication

Anti-hypotensive treatment, which includes dopamine, dobutamine, epinephrine, norepinephrine, milrinone, vasopressin, terlipressin, levosimendan, and glucocorticoids, is a long-established intervention in neonates with arterial hypotension (AH). However, there are still gaps in knowledge and issues that need clarification. The main questions and challenges that neonatologists face relate to the reference ranges of arterial blood pressure in presumably healthy neonates in relation to gestational and postnatal age; the arterial blood pressure level that potentially affects perfusion of critical organs; the incorporation of targeted echocardiography and near-infrared spectroscopy for assessing heart function and cerebral perfusion in clinical practice; the indication, timing, and choice of medication for each individual patient; the limited randomized clinical trials in neonates with sometimes conflicting results; and the sparse data regarding the potential effect of early hypotension or anti-hypotensive medications on long-term neurodevelopment. In this review, after a short review of AH definitions used in neonates and existing data on pathophysiology of AH, we discuss currently available data on pharmacokinetic and hemodynamic effects, as well as the effectiveness and safety of anti-hypotensive medications in neonates. In addition, data on the comparisons between anti-hypotensive medications and current suggestions for the main indications of each medication are discussed.

Combined Inhibition of Phosphodiesterase-5 and -9 in Experimental Heart Failure

BACKGROUND

Intracellular second messenger cyclic guanosine monophosphate (cGMP) mediates bioactivity of the natriuretic peptides and nitric oxide, and is key to circulatory homeostasis and protection against cardiovascular disease. Inhibition of cGMP-degrading phosphodiesterases (PDEs) PDE5 and PDE9 are emerging as pharmacological targets in heart failure (HF).

OBJECTIVES

The present study investigated dual enhancement of cGMP in experimental HF by combining inhibition of PDE-5 (P5-I) and PDE-9 (P9-I).

METHODS

Eight sheep with pacing-induced HF received on separate days intravenous P5-I (sildenafil), P9-I (PF-04749982), P5-I+P9-I, and vehicle control, in counterbalanced order.

RESULTS

Compared with control, separate P5-I and P9-I significantly increased circulating cGMP concentrations in association with reductions in mean arterial pressure (MAP), left atrial pressure (LAP), and pulmonary arterial pressure (PAP), with effects of P5-I on cGMP, MAP, and PAP greater than those of P9-I. Only P5-I decreased pulmonary vascular resistance. Combination P5-I+P9-I further reduced MAP, LAP, and PAP relative to inhibition of either phosphodiesterase alone. P9-I and, especially, P5-I elevated urinary cGMP levels relative to control. However, whereas inhibition of either enzyme increased urine creatinine excretion and clearance, only P9-I induced a significant diuresis and natriuresis. Combined P5-I+P9-I further elevated urine cGMP with concomitant increases in urine volume, sodium and creatinine excretion, and clearance similar to P9-I alone, despite the greater MAP reductions induced by combination treatment.

CONCLUSIONS

Combined P5-I+P9-I amalgamated the superior renal effects of P9-I and pulmonary effects of P5-1, while concurrently further reducing cardiac preload and afterload. These findings support combination P5-I+P9-I as a therapeutic strategy in HF.

Current clinical understanding and effectiveness of portopulmonary hypertension treatment

Portopulmonary hypertension (PoPH) is a rare subtype of Group 1 pulmonary arterial hypertension (PAH) with a poor prognosis. According to the most up-to-date definition, PoPH is characterized by a mean pulmonary arterial pressure (PAP) of >20 mmHg at rest, a pulmonary artery wedge pressure of ≤15 mmHg, and a pulmonary vascular resistance (PVR) of >2 Wood units with portal hypertension. Like PAH, PoPH is underpinned by an imbalance in vasoactive substances. Therefore, current guidelines recommend PAH-specific therapies for PoPH treatment; however, descriptions of the actual treatment approaches are inconsistent. Given the small patient population, PoPH is often studied in combination with idiopathic PAH; however, recent evidence suggests important differences between PoPH and idiopathic PAH in terms of hemodynamic parameters, treatment approaches, survival, socioeconomic status, and healthcare utilization. Therefore, large, multi-center registry studies are needed to examine PoPH in isolation while obtaining statistically meaningful results. PoPH has conventionally been excluded from clinical drug trials because of concerns over hepatotoxicity. Nevertheless, newer-generation endothelin receptor antagonists have shown great promise in the treatment of PoPH, reducing PVR, PAP, and World Health Organization functional class without causing hepatotoxicity. The role of liver transplantation as a treatment option for PoPH has also been controversial; however, recent evidence shows that this procedure may be beneficial in this patient population. In the future, given the shortage of liver donors, predictors of a favorable response to liver transplantation should be determined to select the most eligible patients. Collectively, advances in these three areas could help to standardize PoPH treatment in the clinic.

Pulmonary Vasculature Responsiveness to Phosphodiesterase-5A Inhibition in Heart Failure With Reduced Ejection Fraction: Possible Role of Plasma Potassium

Introduction

Phosphodiesterase-5a inhibition (PDE5i) leads to favorable changes in pulmonary hemodynamic and cardiac output (CO) in patients with advanced heart failure (HF) and reduced ejection fraction (HFrEF). The hemodynamic response to PDE5i could be heterogeneous and the clinical variables associated with these changes are scarcely investigated.

Materials and Methods

Of 260 patients with advanced HFrEF referred for advanced therapies [cardiac transplant/left ventricular assist device (LVAD)], 55 had pulmonary hypertension (PH) and fulfilled the criteria for the PDE5i vasoreactivity test. Right heart catheterization (RHC) was performed as a part of clinical evaluation before and after 20-mg intravenous sildenafil. Absolute and relative changes in pulmonary vascular resistance (PVR) were evaluated to assess hemodynamic response to PDE5i. Clinical, biochemical, and hemodynamic factors associated with PVR changes were identified.

Results

Sildenafil administration reduced PVR (− 45.3%) and transpulmonary gradient (TPG; − 34.8%) and increased CO (+ 13.6%). Relative change analysis showed a negative moderate association between baseline plasma potassium and changes in PVR (r = − 0.48; p = 0.001) and TPG (r = − 0.43; p = 0.005) after PDE5i. Aldosterone concentration shows a direct moderate association with PVR changes after PDE5i. A significant moderate association was also demonstrated between CO improvement and the severity of mitral (r = 0.42; p = 0.002) and tricuspid (r = 0.39; p = 0.004) regurgitation.

Conclusion

We identified plasma potassium, plasma aldosterone level, and atrioventricular valve regurgitations as potential cofounders of hemodynamic response to acute administration of PDE5i. Whether modulation of potassium levels could enhance pulmonary vasoreactivity in advanced HFrEF deserves further research.

Inotropic therapies in heart failure and cardiogenic shock: an educational review

Reduced systolic function is central to the pathophysiology and clinical sequelae of acute decompensated heart failure (ADHF) with reduced ejection fraction and cardiogenic shock. These clinical entities are the final common pathway for marked deterioration of right or left ventricular function and can occur in multiple clinical presentations including severe ADHF, myocardial infarction, post-cardiac surgery, severe pulmonary hypertension, and advanced or end-stage chronic heart failure. Inotropic therapies improve ventricular systolic function and may be divided into three classes on the basis of their mechanism of action (calcitropes, mitotropes, and myotropes). Most currently available therapies for cardiogenic shock are calcitropes which can provide critical haemodynamic support, but also may increase myocardial oxygen demand, ischaemia, arrhythmia, and mortality. Emerging therapies to improve cardiac function such as mitotropes (e.g. perhexiline, SGLT2i) or myotropes (e.g. omecamtiv mecarbil) may provide useful alternatives in the future.

Factors Associated with Ineffectiveness of Sildenafil Treatment in Patients with End-Stage Heart Failure and Elevated Pulmonary Vascular Resistance

Introduction: Elevated pulmonary vascular resistance (PVR) unresponsive to vasodilator treatment is a marker of heart failure (HF) severity, and an important predictor of poor results of heart transplantation (HT). Objective: We sought to analyze factors associated with ineffectiveness of sildenafil treatment in end-stage HF patients with elevated PVR with particular emphasis placed on tenascin-C (TNC) serum concentrations. Patients and Methods: The study is an analysis of 132 end-stage HF patients referred for HT evaluation in the Cardiology Department between 2015 and 2018. TNC was measured by sandwich enzyme-linked immunosorbent assay (Human TNC, SunRedBio Technology, Shanghai, China). The endpoint was PVR > 3 Wood units after the six-month sildenafil therapy. Results: The median age was 58 years, and 90.2% were men. PVR >3 Wood units after 6 months of sildenafil treatment were found in 36.6% patients. The multivariable logistic regression analysis confirmed that TNC (OR = 1.004 (1.002–1.006), p = 0.0003), fibrinogen (OR= 1.019 (1.005–1.033), p = 0.085), creatinine (OR =1.025 (1.004–1.047), p = 0.0223) and right ventricular end-diastolic dimension (RVEDd) (OR = 1.279 (1.074–1.525), p = 0.0059) were independently associated with resistance to sildenafil treatment. Area under the ROC curves indicated an acceptable power of TNC (0.9680 (0.9444–0.9916)), fibrinogen (0.8187 (0.7456–0.8917)) and RVEDd (0.7577 (0.6723–0.8431)), as well as poor strength of creatinine (0.6025 (0.4981–0.7070)) for ineffectiveness of sildenafil treatment. Conclusions: Higher concentrations of TNC, fibrinogen and creatinine, as well as a larger RVEDd are independently associated with the ineffectiveness of sildenafil treatment. TNC has the strongest predictive power, sensitivity and specificity for evaluation of resistance to sildenafil treatment.

Treatment of right ventricular dysfunction and heart failure in pulmonary arterial hypertension

Right heart dysfunction and failure is the principal determinant of adverse outcomes in patients with pulmonary arterial hypertension (PAH). In addition to right ventricular (RV) dysfunction, systemic congestion, increased afterload and impaired myocardial contractility play an important role in the pathophysiology of RV failure. The behavior of the RV in response to the hemodynamic overload is primarily modulated by the ventricular interaction and its coupling to the pulmonary circulation. The presentation can be acute with hemodynamic instability and shock or chronic producing symptoms of systemic venous congestion and low cardiac output. The prognostic factors associated with poor outcomes in hospitalized patients include systemic hypotension, hyponatremia, severe tricuspid insufficiency, inotropic support use and the presence of pericardial effusion. Effective therapeutic management strategies involve identification and effective treatment of the triggering factors, improving cardiopulmonary hemodynamics by optimization of volume to improve diastolic ventricular interactions, improving contractility by use of inotropes, and reducing afterload by use of drugs targeting pulmonary circulation. The medical therapies approved for PAH act primarily on the pulmonary vasculature with secondary effects on the right ventricle. Mechanical circulatory support as a bridge to transplantation has also gained traction in medically refractory cases. The current review was undertaken to summarize recent insights into the evaluation and treatment of RV dysfunction and failure attributable to PAH.

Management of Cardiogenic Shock in a Cardiac Intensive Care Unit

Cardiogenic shock (CS) is a complex condition characterized by end-organ hypoperfusion and requiring pharmacologic and/or mechanical circulatory support. It is caused by a decline in cardiac output due to a primary cardiac disorder. CS is frequently complicated by multiorgan system dysfunction that requires a multidisciplinary approach in a critical care setting. Appropriate use of diagnostic data using tools available in a modern cardiac intensive care unit should guide optimal management incorporating both pharmacologic and nonpharmacologic therapies to minimize morbidity and mortality.

Phosphodiesterase 5 inhibitors for pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) comprises a group of complex and heterogenous conditions, characterised by elevated pulmonary artery pressure, and which left untreated leads to right-heart failure and death. PH includes World Health Organisation (WHO) Group 1 pulmonary arterial hypertension (PAH); Group 2 consists of PH due to left-heart disease (PH-LHD); Group 3 comprises PH as a result of lung diseases or hypoxia, or both; Group 4 includes PH due to chronic thromboembolic occlusion of pulmonary vasculature (CTEPH), and Group 5 consists of cases of PH due to unclear and/or multifactorial mechanisms including haematological, systemic, or metabolic disorders. Phosphodiesterase type 5 (PDE5) inhibitors increase vasodilation and inhibit proliferation.

OBJECTIVES

To determine the efficacy of PDE5 inhibitors for pulmonary hypertension in adults and children.

SEARCH METHODS

We performed searches of CENTRAL, MEDLINE, Embase, CINAHL, and Web of Science up to 26 September 2018. We handsearched review articles, clinical trial registries, and reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised controlled trials that compared any PDE5 inhibitor versus placebo, or any other PAH disease-specific therapies, for at least 12 weeks. We include separate analyses for each PH group.

DATA COLLECTION AND ANALYSIS

We imported studies identified by the search into a reference manager database. We retrieved the full-text versions of relevant studies, and two review authors independently extracted data. Primary outcomes were: change in WHO functional class, six-minute walk distance (6MWD), and mortality. Secondary outcomes were haemodynamic parameters, quality of life/health status, dyspnoea, clinical worsening (hospitalisation/intervention), and adverse events. When appropriate, we performed meta-analyses and subgroup analyses by severity of lung function, connective tissue disease diagnosis, and radiological pattern of fibrosis. We assessed the evidence using the GRADE approach and created 'Summary of findings' tables.

MAIN RESULTS

We included 36 studies with 2999 participants (with pulmonary hypertension from all causes) in the final review. Trials were conducted for 14 weeks on average, with some as long as 12 months. Two trials specifically included children.Nineteen trials included group 1 PAH participants. PAH participants treated with PDE5 inhibitors were more likely to improve their WHO functional class (odds ratio (OR) 8.59, 95% confidence interval (CI) 3.95 to 18.72; 4 trials, 282 participants), to walk 48 metres further in 6MWD (95% CI 40 to 56; 8 trials, 880 participants), and were 22% less likely to die over a mean duration of 14 weeks (95% CI 0.07 to 0.68; 8 trials, 1119 participants) compared to placebo (high-certainty evidence). The number needed to treat to prevent one additional death was 32 participants. There was an increased risk of adverse events with PDE5 inhibitors, especially headache (OR 1.97, 95% CI 1.33 to 2.92; 5 trials, 848 participants), gastrointestinal upset (OR 1.63, 95% CI 1.07 to 2.48; 5 trials, 848 participants), flushing (OR 4.12, 95% CI 1.83 to 9.26; 3 trials, 748 participants), and muscle aches and joint pains (OR 2.52, 95% CI 1.59 to 3.99; 4 trials, 792 participants).Data comparing PDE5 inhibitors to placebo whilst on other PAH-specific therapy were limited by the small number of included trials. Those PAH participants on PDE5 inhibitors plus combination therapy walked 19.66 metres further in six minutes (95% CI 9 to 30; 4 trials, 509 participants) compared to placebo (moderate-certainty evidence). There were limited trials comparing PDE5 inhibitors directly with other PAH-specific therapy (endothelin receptor antagonists (ERAs)). Those on PDE5 inhibitors walked 49 metres further than on ERAs (95% CI 4 to 95; 2 trials, 36 participants) (low-certainty evidence). There was no evidence of a difference in WHO functional class or mortality across both treatments.Five trials compared PDE5 inhibitors to placebo in PH secondary to left-heart disease (PH-LHD). The quality of data were low due to imprecision and inconsistency across trials. In those with PH-LHD there were reduced odds of an improvement in WHO functional class using PDE5 inhibitors compared to placebo (OR 0.53, 95% CI 0.32 to 0.87; 3 trials, 285 participants), and those using PDE5 inhibitors walked 34 metres further compared to placebo (95% CI 23 to 46; 3 trials, 284 participants). There was no evidence of a difference in mortality. Five trials compared PDE5 inhibitors to placebo in PH secondary to lung disease/hypoxia, mostly in COPD. Data were of low quality due to imprecision of effect and inconsistency across trials. There was a small improvement of 27 metres in 6MWD using PDE5 inhibitors compared to placebo in those with PH due to lung disease. There was no evidence of worsening hypoxia using PDE5 inhibitors, although data were limited. Three studies compared PDE5 inhibitors to placebo or other PAH-specific therapy in chronic thromboembolic disease. There was no significant difference in any outcomes. Data quality was low due to imprecision of effect and heterogeneity across trials.

AUTHORS' CONCLUSIONS

PDE5 inhibitors appear to have clear beneficial effects in group 1 PAH. Sildenafil, tadalafil and vardenafil are all efficacious in this clinical setting, and clinicians should consider the side-effect profile for each individual when choosing which PDE5 inhibitor to prescribe.While there appears to be some benefit for the use of PDE5 inhibitors in PH-left-heart disease, it is not clear based on the mostly small, short-term studies, which type of left-heart disease stands to benefit. These data suggest possible harm in valvular heart disease. There is no clear benefit for PDE5 inhibitors in pulmonary hypertension secondary to lung disease or chronic thromboembolic disease. Further research is required into the mechanisms of pulmonary hypertension secondary to left-heart disease, and cautious consideration of which subset of these patients may benefit from PDE5 inhibitors. Future trials in PH-LHD should be sufficiently powered, with long-term follow-up, and should include invasive haemodynamic data, WHO functional class, six-minute walk distance, and clinical worsening.

Intravenous sildenafil acutely improves hemodynamic response to exercise in patients with connective tissue disease

Background

Hemodynamic assessment during exercise may unmask an impaired functional reserve of the right ventricle and the pulmonary vasculature in patients with connective tissue disease. We assessed the effect of intravenous sildenafil on the hemodynamic response to exercise in patients with connective tissue disease.

Methods

In this proof-of-concept study, patients with connective tissue disease and mean pulmonary arterial pressure (mPAP) >20 mm Hg were subjected to a supine exercise hemodynamic evaluation before and after administration of intravenous sildenafil 10 mg.

Results

Ten patients (four with moderately elevated mPAP 21–24 mm Hg; six with mPAP >25 mm Hg) underwent hemodynamic assessment. All of them showed markedly abnormal exercise hemodynamics. Intravenous sildenafil was well tolerated and had significant hemodynamic effects at rest and during exercise, although without pulmonary selectivity. Sildenafil reduced median total pulmonary resistance during exercise from 6.22 (IQR 4.61–8.54) to 5.24 (3.95–6.96) mm Hg·min·L^-1 (p = 0.005) and increased median pulmonary arterial capacitance during exercise from 1.59 (0.93–2.28) to 1.74 (1.12–2.69) mL/mm Hg (p = 0.005).

Conclusions

In patients with connective tissue disease who have an abnormal hemodynamic response to exercise, intravenous sildenafil improved adaption of the right ventricular-pulmonary vascular unit to exercise independent of resting mPAP. The impact of acute pharmacological interventions on exercise hemodynamics in patients with pulmonary vascular disease warrants further investigation.

Trial registration

Clinicaltrials.gov NCT01889966.

Pulmonary Arterial Hypertension Specific Therapy in Patients with Combined Post- and Precapillary Pulmonary Hypertension

Background

Specific therapy for patients with PAH is associated with good outcomes. Little is known about the effect of this treatment in patients with Cpc-PH (PAPm ≥ 25 mmHg, PAWP > 15 mmHg, DPG ≥ 7 mmHg, and/or PVR > 3 WU). This study evaluates the outcome of treating patients with Cpc-PH using PAH specific therapy.

Methods

The primary outcome was survival. Secondary outcomes were WHO functional class and 6-minute walk distance (6-MWD).

Results

Twenty-six patients with Cpc-PH (half with VHD and half with HF) received PAHST. Six patients did not tolerate treatment due to pulmonary edema. No predictors for treatment intolerance were identified. In twenty patients who tolerated the treatment, the mean WHO functional class improved from 2.70 ± 0.21 at initial assessment to 2.22 ± 0.21 (p < 0.04) and 2.06 ± 0.21 (p < 0.03) at 6 and 9 months, respectively. Mean 6-MWD improved from 276.0 ± 38.50 meters at initial assessment to 343.9 ± 22.99 meters (p < 0.04) and 364.6 ± 34.85 meters (p = 0.07) at 6 and 9 months, respectively. Twelve patients died during the follow-up period. Mean survival for all patients was 1279.7 ± 193.60 days.

Conclusion

PAHST may be beneficial in the treatment of Cpc-PH (both short and long term). Prospective randomized controlled trials of PAHST in this population are needed to assess its potential efficacy.

Acute decompensated pulmonary hypertension

Acute right heart failure in chronic precapillary pulmonary hypertension is characterised by a rapidly progressive syndrome with systemic congestion resulting from impaired right ventricular filling and/or reduced right ventricular flow output. This clinical picture results from an imbalance between the afterload imposed on the right ventricle and its adaptation capacity. Acute decompensated pulmonary hypertension is associated with a very poor prognosis in the short term. Despite its major impact on survival, its optimal management remains very challenging for specialised centres, without specific recommendations. Identification of trigger factors, optimisation of fluid volume and pharmacological support to improve right ventricular function and perfusion pressure are the main therapeutic areas to consider in order to improve clinical condition. At the same time, specific management of pulmonary hypertension according to the aetiology is mandatory to reduce right ventricular afterload. Over the past decade, the development of extracorporeal life support in refractory right heart failure combined with urgent transplantation has probably contributed to a significant improvement in survival for selected patients. However, there remains a considerable need for further research in this field.

Acute decompensated PH is a life-threatening condition requiring specific management in a specialised centrehttp://ow.ly/non530fkhmA

Phosphodiesterase type 5 and cancers: progress and challenges

Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.

Effect of Milrinone Infusion on Pulmonary Vasculature and Stroke Work Indices: A Single-Center Retrospective Analysis in 69 Patients Awaiting Cardiac Transplantation

BACKGROUND

Although milrinone infusion is reported to benefit left ventricular function in chronic left heart failure, few insights exist regarding its effects on pulmonary circulation and right ventricular function.

METHODS

We retrospectively reviewed right heart catheterization data at baseline and during continuous infusion of milrinone in 69 patients with advanced heart failure and analyzed the effects on ventricular stroke work indices, pulmonary vascular resistance and pulmonary arterial compliance.

RESULTS

Compared to baseline, milrinone infusion after a mean 58 ± 61 days improved mean left ventricular stroke work index (1540 ± 656 vs. 2079 ± 919 mmHg·mL/m², p = 0.0007) to a much greater extent than right ventricular stroke work index (616 ± 346 vs. 654 ± 332, p = 0.053); however, patients with below median stroke work indices experienced a significant improvement in both left and right ventricular stroke work performance. Overall, milrinone reduced left and right ventricular filling pressures and pulmonary and systemic vascular resistance by approximately 20%. Despite an increase in pulmonary artery capacitance (2.3 ± 1.6 to 3.0 ± 2.0, p = 0.013) and a reduction in pulmonary vascular resistance (3.8 ± 2.3 to 3.0 ± 1.7 Wood units), milrinone did not reduce the transpulmonary gradient (13 ± 7 vs. 12 ± 6 mmHg, p = 0.252), the pulmonary artery pulse pressure (25 ± 10 vs. 24 ± 10, p = 0.64) or the pulmonary artery diastolic to pulmonary capillary wedge gradient (2.0 ± 6.5 vs. 2.4 ± 6.0, p = 0.353).

CONCLUSION

Milrinone improved left ventricular stroke work indices to a greater extent than right ventricular stroke work indices and had beneficial effects on right ventricular net input impedance, predominantly via augmentation of left ventricular stroke volume and passive unloading of the pulmonary circuit. Patients who had the worst biventricular performance benefited the most from chronic milrinone infusion.

Useful Implications of Low-dose Long-term Use of PDE-5 Inhibitors

INTRODUCTION

Phosphodiesterase type 5 (PDE-5) hydrolyzes cyclic guanylate monophosphate (cGMP) specifically to 5' GMP, promoting successful corporeal vascular relaxation and penile erection during sexual stimulation. Oral PDE-5 inhibitors such as sildenafil, vardenafil, tadalafil, and avanafil have provided noninvasive, effective, well-tolerated treatment for erectile dysfunction (ED) patients and, at the same time, stimulated both academic and clinical interests. Lately, some oral PDE-5 inhibitors were released as low-dose preparations with the concept of potential daily administration and long-term use.

AIM

To highlight the possible potential implications of low-dose long-term use of PDE-5 inhibitors.

METHOD

A systematic review was carried out until December 2015 based on a search of all concerned articles in MEDLINE, medical subjects heading (MeSH) databases, Scopus, The Cochrane Library, EMBASE, and CINAHL databases without language restriction. Key words used to assess the outcome and estimates for concerned associations were: PDE-5 inhibitors; erectile dysfunction; low-dose; long-term; sildenafil; tadalafil; vardenafil; avanafil.

MAIN OUTCOME MEASURES

Demonstrating different implications for low-dose long-term use of PDE-5 inhibitors.

RESULTS

Low-dose and/or long-term use of PDE-5 inhibitors was shown to put forth beneficial sound effects in different medical implications with potentials that could be extended for different utilities. These implications included sexual, urogenital, cardiovascular, pulmonary, cutaneous, gastrointestinal, and reproductive, as well as neurological disorders. However, it is evident that most potential appliances were carried out experimentally on preclinical studies with off-label indications.

CONCLUSION

Making use of and exploring low-dose and/or long-term use of several PDE-5 inhibitors for their possible implications seem to be valuable in different medical disorders. Increased knowledge of the drug characteristics, comparative treatment regimens, optimal prescribing patterns, and well-designed clinical trials are needed before these agents can be recommended for use.

Inhaled therapy for the management of perioperative pulmonary hypertension

Patients with pulmonary hypertension (PH) are at high risk for complications in the perioperative setting and often receive vasodilators to control elevated pulmonary artery pressure (PAP). Administration of vasodilators via inhalation is an effective strategy for reducing PAP while avoiding systemic side effects, chiefly hypotension. The prototypical inhaled pulmonary-specific vasodilator, nitric oxide (NO), has a proven track record but is expensive and cumbersome to implement. Alternatives to NO, including prostanoids (such as epoprostenol, iloprost, and treprostinil), NO-donating drugs (sodium nitroprusside, nitroglycerin, and nitrite), and phosphodiesterase inhibitors (milrinone, sildenafil) may be given via inhalation for the purpose of treating elevated PAP. This review will focus on the perioperative therapy of PH using inhaled vasodilators.

Hemodynamic instability in the critically ill neonate: An approach to cardiovascular support based on disease pathophysiology

Hemodynamic disturbance in the sick neonate is common, highly diverse in underlying pathophysiology and dynamic. Dysregulated systemic and cerebral blood flow is hypothesized to have a negative impact on neurodevelopmental outcome and survival. An understanding of the physiology of the normal neonate, disease pathophysiology, and the properties of vasoactive medications may improve the quality of care and lead to an improvement in survival free from disability. In this review we present a modern approach to cardiovascular therapy in the sick neonate based on a more thoughtful approach to clinical assessment and actual pathophysiology. Targeted neonatal echocardiography offers a more detailed insight into disease processes and offers longitudinal assessment, particularly response to therapeutic intervention. The pathophysiology of common neonatal conditions and the properties of cardiovascular agents are described. In addition, we outline separate treatment algorithms for various hemodynamic disturbances that are tailored to clinical features, disease characteristics and echocardiographic findings.

Preoperative Sildenafil administration in children undergoing cardiac surgery: a randomized controlled preconditioning study

OBJECTIVES

Sildenafil has strong cardiac preconditioning properties in animal studies and has a safe side-effect profile in children. Therefore, we evaluated the application of Sildenafil preconditioning to reduce myocardial ischaemia/reperfusion injury in children undergoing surgical ventricular septal defect (VSD) closure.

METHODS

This is a randomized, double-blind study. Children (1-17 years) undergoing VSD closure were randomized into three groups: placebo (Control group), preconditioning with 0.06 mg/kg (Sild-L group) and 0.6 mg/kg Sildenafil (Sild-H group).

PRIMARY ENDPOINT

troponin release. CK-MB, Troponin I, inflammatory response (IL-6 and TNF-α), bypass and ventilation weaning times, inotropy score and echocardiographic function were assessed. Data expressed as median (range), and a value of P < 0.05 was considered significant.

RESULTS

Thirty-nine patients were studied (13/group). Aortic cross-clamp time was similar [27 (18-85) and 27 (12-39) min] in the Control and Sild-L groups, respectively, but significantly longer [39 (20-96) min] in the Sild-H group when compared with the Control group. Area under the curve of CK-MB release was 1105 (620-1855) h ng/ml in the Control group, 1672 (564-2767) h ng/ml in the Sild-L group and was significantly higher in the Sild-H group [1695 (1252-3377) h ng/ml] when compared with the Control group. There were no significant differences in inflammatory response markers, cardiopulmonary bypass and ventilation weaning times, inotropy scores and echocardiographic function between the groups.

CONCLUSIONS

In this small study, Sildenafil failed to reduce myocardial injury in children undergoing cardiac surgery, nor does it alter cardiac function, inotropic needs or postoperative course. A subclinical increase in cardiac enzyme release after Sildenafil preconditioning cannot be excluded.

CLINICAL TRIALS REGISTRY

CTRI/2014/03/004468.

Perioperative management of pulmonary hypertension during lung transplantation (a lesson for other anaesthesia settings)

Patients with pulmonary hypertension are some of the most challenging for an anaesthesiologist to manage. Pulmonary hypertension in patients undergoing surgical procedures is associated with high morbidity and mortality due to right ventricular failure, arrhythmias and ischaemia leading to haemodynamic instability. Lung transplantation is the only therapeutic option for end-stage lung disease. Patients undergoing lung transplantation present a variety of challenges for anaesthesia team, but pulmonary hypertension remains the most important. The purpose of this article is to review the anaesthetic management of pulmonary hypertension during lung transplantation, with particular emphasis on the choice of anaesthesia, pulmonary vasodilator therapy, inotropic and vasopressor therapy, and the most recent intraoperative monitoring recommendations to optimize patient care.

Inotropes do not increase mortality in advanced heart failure

Inotrope use is one of the most controversial topics in the management of heart failure. While the heart failure community utilizes them and recognizes the state of inotrope dependency, retrospective analyses and registry data have overwhelmingly suggested high mortality, which is logically to be expected given the advanced disease states of those requiring their use. Currently, there is a relative paucity of randomized control trials due to the ethical dilemma of creating control groups by withholding inotropes from patients who require them. Nonetheless, results of such trials have been mixed. Many were also performed with agents no longer in use, on patients without an indication for inotropes, or at a time before automatic cardio-defibrillators were recommended for primary prevention. Thus, their results may not be generalizable to current clinical practice. In this review, we discuss current indications for inotrope use, specifically dobutamine and milrinone, depicting their mechanisms of action, delineating their patterns of use in clinical practice, defining the state of inotrope dependency, and ultimately examining the literature to ascertain whether evidence is sufficient to support the current view that these agents increase mortality in patients with heart failure. Our conclusion is that the evidence is insufficient to link inotropes and increased mortality in low output heart failure.

[Management of patients with pulmonary hypertension]

Due to the increased survival of patients with pulmonary hypertension, even non-cardiac anesthesiologists will see these patients more frequently for anesthesia. The hemodynamic goal in the perioperative period is to avoid an increase in pulmonary vascular resistance (PVR) and to reduce a possibly pre-existing elevated PVR. Acute increases of chronically elevated PVR may result from hypoxia, hypercapnia, acidosis, hypothermia, elevated sympathetic output and also release of endogenous or application of exogenous pulmonary vasoconstrictors. Early recognition and treatment of these changes might be life saving in these patients. Drug interventions to perioperatively reduce PVR include administration of pulmonary vasodilators, such as oxygen, prostacyclines (epoprostenol, iloprost), phosphodiesterase III (milrinone) and V (sildenafil) inhibitors, as well as nitrates and nitric oxide. Along with the concept of selective pulmonary vasodilation inhalative administration of pulmonary vasodilators has benefits compared to intravenous administration. New therapeutic strategies, such as inhalational iloprost, inhalational milrinone and intravenous sildenafil can be introduced without significant technical support even in smaller departments.

Additional use of a phosphodiesterase 5 inhibitor in patients with pulmonary hypertension secondary to chronic systolic heart failure: a meta-analysis

AIMS

Increased indiscriminate use of pulmonary artery hypertension-targeted drugs has been observed in patients with pulmonary hypertension (PH) secondary to heart failure. We performed a meta-analysis to evaluate the chronic effects of using phosphodiesterase 5 (PDE5) inhibitors to treat patients with PH secondary to chronic systolic heart failure.

METHODS AND RESULTS

PubMed, EMBASE, and the Cochrane Library were searched up to October 2013 for randomized controlled trials (RCTs) assessing PDE5 inhibitor treatments in PH patients secondary to chronic heart failure. Six RCTs involving 206 chronic systolic heart failure patients with PH complications were included. Sildenafil was used in all trials. Sildenafil treatment resulted in fewer hospital admissions compared with the placebo treatment (3.15% vs. 12.20%; risk ratio 0.29; 95% confidence interval 0.11-0.77). Various haemodynamic parameters were improved with additional sildenafil treatment, including reduced mean pulmonary artery pressure [weighted mean difference (WMD) -5.71 mmHg, P<0.05] and pulmonary vascular resistance (WMD -81.5 dynes/cm(-5), P<0.00001), increased LVEF (WMD 3.95%, P<0.01), and unchanged heart rate and blood pressure. The exercise capacity improved (oxygen consumption at peak exercise, WMD 3.20 mL/min(-1)/kg(-1), P<0.00001; ventilation to CO2 production slope, WMD -5.89, P<0.00001), and the clinical symptoms were relieved based on the breathlessness (WMD 7.72, P<0.00001), fatigue (WMD 2.28, P<0.05), and emotional functioning (WMD 5.92, P<0.00001) scores.

CONCLUSIONS

Additional sildenafil treatment is a potential therapeutic method to improve pulmonary exercise capacity and quality of life by ameliorating PH in patients with chronic systolic heart failure.

Acute effects of sildenafil and dobutamine in the hypertrophic and failing right heart in vivo

Abstract The purpose of this study was to investigate whether acute intravenous administration of the phosphodiesterase type 5 (PDE-5) inhibitor sildenafil in a single clinically relevant dose improves the in vivo function of the hypertrophic and failing right ventricle (RV). Wistar rats ([Formula: see text]) were subjected to pulmonary trunk banding (PTB) causing RV hypertrophy and failure. Four weeks after surgery, they were randomized to receive an intravenous bolus dose of sildenafil (1 mg/kg; [Formula: see text]), vehicle ([Formula: see text]), or dobutamine (10 μg/kg; [Formula: see text]). Invasive RV pressures were recorded continuously, and transthoracic echocardiography was performed 1, 5, 15, 25, 35, 50, 70, and 90 minutes after injecting the bolus. Cardiac function was compared to baseline measurements to evaluate the in vivo effects of each specific treatment. The PTB procedure caused significant hypertrophy, cardiac fibrosis, and reduction in RV function evaluated by echocardiography (TAPSE) and invasive pressure measurements. Sildenafil did not improve the function of the hypertrophic failing right heart in vivo, measured by TAPSE, RV systolic pressure (RVsP), and dp/dtmax. Dobutamine improved RV function 1 minute after injection measured by TAPSE ([Formula: see text] vs. [Formula: see text] cm; [Formula: see text]), RVsP ([Formula: see text] vs. [Formula: see text] mmHg; [Formula: see text]), and dp/dtmax ([Formula: see text] vs. [Formula: see text] mmHg/s; [Formula: see text]). Acute administration of the PDE-5 inhibitor sildenafil in a single clinically relevant dose did not modulate the in vivo function of the hypertrophic failing right heart of the rat measured by echocardiography and invasive hemodynamics. In the same model, dobutamine acutely improved RV function.

Response to a single dose of sildenafil in single-ventricle patients: an echocardiographic evaluation

New evidence of increased phosphodiesterase-5 (PDE-5) in hypertrophied human myocardium suggests that sildenafil, a selective PDE-5 inhibitor, may improve muscle contraction and therefore improve ventricular function. The purpose of this study was to compare ventricular function as assessed by echocardiography in 10 surgically palliated single-ventricle patients at baseline and again after a single dose of sildenafil. The velocity time integral of the ventricular outflow tract was increased 2 h after sildenafil administration (p = 0.01), thus suggesting an improvement in cardiac output.

Acute pulmonary vasoreactivity test with sildenafil or nitric monoxide before left ventricular assist device implantation

There has been no established medical therapy to ameliorate pulmonary hypertension (PH) owing to left heart disease (LHD-PH). It has recently been shown that the left ventricular assist device (LVAD) can improve LHD-PH and therefore has the potential to become a major bridge tool for heart transplantation (HTx). However, some patients still have persistent PH even after LVAD treatment. It is essential to demonstrate the reversibility of end-organ dysfunction, including PH, prior to implantable LVAD treatment, especially in Japan, because implantable LVAD treatment is indicated only as bridge to transplantation. Here we report a patient with LHD-PH whose PH was demonstrated to be reversible by the acute pulmonary vasoreactivity test (APVT) with nitrogen monoxide (NO) and the phosphodiesterase-5 inhibitor sildenafil. Both inhaled NO and sildenafil reduced pulmonary vascular resistance, but pulmonary capillary wedge pressure was increased by NO, which was conversely decreased under increased cardiac output by sildenafil. After the patient was listed as an HTx recipient, pulmonary vascular resistance recovered down to an acceptable range with LVAD treatment. Based on these findings, we suggest that the APVT with sildenafil may be a useful and safe tool to predict improvement of PH after LVAD treatment.

Hemodynamic and clinical benefits associated with chronic sildenafil therapy in advanced heart failure: experience of the Montréal Heart Institute

BACKGROUND

Pulmonary hypertension is highly prevalent in advanced heart failure (HF) despite optimal medical and device therapies. The objective of this investigation was to report on a single centre's experience of open-label chronic sildenafil therapy in patients with advanced HF.

METHODS

We conducted a retrospective systematic medical record review of all patients evaluated at our institution for heart transplantation who had also been treated with chronic sildenafil therapy. Baseline demographics, comorbidities, and concomitant medications, as well as the results of laboratory investigations and physiological testing, were abstracted from patient medical records. Change in systolic and mean pulmonary artery pressure (PAP), transpulmonary gradient, cardiac output and cardiac index, and selected laboratory parameters was analyzed by means of the Wilcoxon rank sum test. Outcomes of interest included New York Heart Association (NYHA) functional class after 6 months of therapy and adverse effects attributable to sildenafil.

RESULTS

The 16 patients undergoing evaluation for cardiac transplantation combined for 4166 patient-days on sildenafil, with a mean dose of 102.5 ± 54.0 mg/d. None discontinued because of side effects. At 6 months, there was an improvement in the cardiac index (P = 0.014) and systolic PAP (P = 0.049) without any significant change in other hemodynamic parameters. Ten patients (62.5%) experienced an improvement in their NYHA functional class, 8 (50%) received a heart transplantation, and 2 (12.5%) improved sufficiently to be removed from the transplant list.

CONCLUSION

Chronic sildenafil therapy was well tolerated and associated with improved functional capacity and decreased systolic PAP. Properly controlled randomized studies of the long-term usefulness of sildenafil therapy in advanced HF populations are warranted.

Perioperative management of pulmonary hypertension in children with critical heart disease

OPINION STATEMENT

Pulmonary hypertension (PHTN) is common to a variety of conditions occurring in infants and children presenting to the intensive care unit. A fundamental understanding of the response of the right ventricle to an increase in afterload and the clinical syndromes responsible for PHTN is essential for managing patients with PHTN and critical heart disease. There are important distinguishing features between PHTN syndromes, and although one form of PHTN may predominate, often more than one mechanism of PHTN is contributing to the pathophysiologic state. Thus, it is imperative to tailor therapies accordingly in order to optimize outcomes.

Pulmonary hypertension associated with left heart disease: characteristics, emerging concepts, and treatment strategies

Left heart disease (LHD) represents the most common causes of pulmonary hypertension (PH). Whether caused by systolic or diastolic dysfunction or valvular heart disease, a hallmark of PH associated with LHD is elevated left atrial pressure. In all cases, the increase in left atrial pressure causes a passive increase in pulmonary pressure. In some patients, a superimposed active component caused by pulmonary arterial vasoconstriction and vascular remodeling may lead to a further increase in pulmonary arterial pressure. When present, PH is associated with a worse prognosis in patients with LHD. In addition to local abnormalities in nitric oxide and endothelin production, gene modifiers such as serotonin polymorphisms may be associated with the pathogenesis of PH in LHD. Optimizing heart failure regimens and corrective valve surgery represent the cornerstone of the treatment of PH in LHD. Recent studies suggest that sildenafil, a phosphodiesterase-5 inhibitor, is a promising agent in the treatment of PH in LHD. Unloading the left ventricle with circulatory support may also reverse severe PH in patients with end-stage heart failure allowing candidacy to heart transplantation.

Role of phosphodiesterases in adult-onset pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by increased mean pulmonary artery pressure (mPAP) due to vasoconstriction and structural changes in the small pulmonary arteries (PAs); proliferation of pulmonary artery smooth muscle cells (PASMCs) contributes to the remodeling. The abnormal pathophysiology in the pulmonary vasculature relates to decreased cyclic nucleotide levels in PASMCs. Phosphodiesterases (PDEs) catalyze the hydrolysis of cAMP and cGMP, thereby PDE inhibitors are effective in vasodilating the PA and decreasing PASMC proliferation. Experimental studies support the use of PDE3, PDE5, and PDE1 inhibitors in PAH. PDE5 inhibitors such as sildenafil are clinically approved to treat different forms of PAH and lower mPAP, increase functional capacity, and decrease right ventricular hypertrophy, without decreasing systemic arterial pressure. New evidence suggests that the combination of PDE inhibitors with other therapies for PAH may be beneficial in treating the disease. Furthermore, inhibiting PDEs in the heart and the inflammatory cells that infiltrate the PA may offer new targets to reduce right ventricular hypertrophy and inhibit inflammation that is associated with and contributes to the development of PAH. This chapter summarizes the advances in the area and the future of PDEs in PAH.

Role of cGMP and cAMP in the hemodynamic response to intrathecal sildenafil administration

INTRODUCTION

Results from our laboratory have demonstrated that intracerebroventricular administration of sildenafil to conscious rats promoted a noticeable increase in both lumbar sympathetic activity and heart rate, with no change in the mean arterial pressure. The intracerebroventricular administration of sildenafil may have produced the hemodynamic effects by activating sympathetic preganglionic neurons in the supraspinal regions and spinal cord. It is well documented that sildenafil increases intracellular cGMP levels by inhibiting phosphodiesterase type 5 and increases cAMP levels by inhibiting other phosphodiesterases.

OBJECTIVE

To examine and compare, in conscious rats, the hemodynamic response following the intrathecal administration of sildenafil, 8-bromo-cGMP (an analog of cGMP), forskolin (an activator of adenylate cyclase), or dibutyryl-cAMP (an analog of cAMP) in order to elucidate the possible role of the sympathetic preganglionic neurons in the observed hemodynamic response.

RESULTS

The hemodynamic responses observed following intrathecal administration of the studied drugs demonstrated the following: 1) sildenafil increased the mean arterial pressure and heart rate in a dose-dependent manner, 2) increasing doses of 8-bromo-cGMP did not alter the mean arterial pressure and heart rate, 3) forskolin did not affect the mean arterial pressure but did increase the heart rate and 4) dibutyryl-cAMP increased the mean arterial pressure and heart rate, similar to the effect observed following the intrathecal injection of the highest dose of sildenafil.

CONCLUSION

Overall, the findings of the current study suggest that the cardiovascular response following the intrathecal administration of sildenafil to conscious rats involves the inhibition of phosphodiesterases other than phosphodiesterase type 5 that increase the cAMP level and the activation of sympathetic preganglionic neurons.

Pulmonary vascular and right ventricular dysfunction in adult critical care: current and emerging options for management: a systematic literature review

INTRODUCTION

Pulmonary vascular dysfunction, pulmonary hypertension (PH), and resulting right ventricular (RV) failure occur in many critical illnesses and may be associated with a worse prognosis. PH and RV failure may be difficult to manage: principles include maintenance of appropriate RV preload, augmentation of RV function, and reduction of RV afterload by lowering pulmonary vascular resistance (PVR). We therefore provide a detailed update on the management of PH and RV failure in adult critical care.

METHODS

A systematic review was performed, based on a search of the literature from 1980 to 2010, by using prespecified search terms. Relevant studies were subjected to analysis based on the GRADE method.

RESULTS

Clinical studies of intensive care management of pulmonary vascular dysfunction were identified, describing volume therapy, vasopressors, sympathetic inotropes, inodilators, levosimendan, pulmonary vasodilators, and mechanical devices. The following GRADE recommendations (evidence level) are made in patients with pulmonary vascular dysfunction: 1) A weak recommendation (very-low-quality evidence) is made that close monitoring of the RV is advised as volume loading may worsen RV performance; 2) A weak recommendation (low-quality evidence) is made that low-dose norepinephrine is an effective pressor in these patients; and that 3) low-dose vasopressin may be useful to manage patients with resistant vasodilatory shock. 4) A weak recommendation (low-moderate quality evidence) is made that low-dose dobutamine improves RV function in pulmonary vascular dysfunction. 5) A strong recommendation (moderate-quality evidence) is made that phosphodiesterase type III inhibitors reduce PVR and improve RV function, although hypotension is frequent. 6) A weak recommendation (low-quality evidence) is made that levosimendan may be useful for short-term improvements in RV performance. 7) A strong recommendation (moderate-quality evidence) is made that pulmonary vasodilators reduce PVR and improve RV function, notably in pulmonary vascular dysfunction after cardiac surgery, and that the side-effect profile is reduced by using inhaled rather than systemic agents. 8) A weak recommendation (very-low-quality evidence) is made that mechanical therapies may be useful rescue therapies in some settings of pulmonary vascular dysfunction awaiting definitive therapy.

CONCLUSIONS

This systematic review highlights that although some recommendations can be made to guide the critical care management of pulmonary vascular and right ventricular dysfunction, within the limitations of this review and the GRADE methodology, the quality of the evidence base is generally low, and further high-quality research is needed.

Pulmonary hypertension in heart failure

BACKGROUND

Pulmonary hypertension occurs in 60% to 80% of patients with heart failure and is associated with high morbidity and mortality.

METHODS AND RESULTS

Pulmonary artery pressure correlates with increased left ventricular end-diastolic pressure. Therefore, pulmonary hypertension is a common feature of heart failure with preserved as well as reduced systolic function. Pulmonary hypertension is partially reversible with normalization of cardiac filling pressures. Pulmonary vasculature remodeling and vasoconstriction create a second component, which does not reverse immediately, but has been shown to improve with vasoactive drugs and especially with left ventricular assist devices.

CONCLUSION

Many drugs used for idiopathic pulmonary arterial hypertension are being considered as treatment options for heart failure-related pulmonary hypertension. This is of particular significance in the heart transplant population. Randomized clinical trials with interventions targeting heart failure patients with elevated pulmonary artery pressure would be justified.

Heart rate in ischemic heart disease. The innovation of ivabradine: more than pure heart rate reduction

A wealth of data suggests that heart rate (HR) is an independent predictor of cardiovascular and all-cause mortality in men and women of all ages with and without cardiovascular disease. Data gathered from clinical trials suggest that HR reduction is an important mechanism of benefit of HR-lowering drugs. A high HR has direct detrimental effects not only on myocardial ischemia but also on the progression of atherosclerosis, ventricular arrhythmias, and on left ventricular function. The risk increases with HR >60 b.p.m. Ivabradine, a drug that slows HR though an effect on the If channels, has been approved for the control of myocardial ischemia in patients with coronary artery disease intolerant to beta-blockers. More recently, the indication of ivabradine has been extended for use in association with beta-blockers in patients with coronary artery disease. The effects of ivabradine on myocardial ischemia are greater than those predicted by pure HR reduction with beta-blockers, suggesting additional mechanisms of action.