One-year follow-up of the effects of sildenafil on pulmonary arterial hypertension and veno-occlusive disease

Acute venodilation properties of low-dose intravenous nitroglycerine in pulmonary veno-occlusive disease: a case report

Background

The use of pulmonary vasodilators for pulmonary arterial hypertension (PAH) has led to a favourable prognosis. In contrast, pulmonary veno-occlusive disease (PVOD) is characterized by the possibility of severe pulmonary oedema after specific PAH therapy. Pulmonary oedema presumably develops in association with pulmonary arterial vasodilation without concomitant pulmonary venodilation. The venous circulation maximally dilates with small amounts of nitroglycerine.

Case summary

A 59-year-old woman with advanced PVOD was referred to our hospital. We performed a right heart catheterization after administering combination therapy with selexipag and macitentan, and intravenous nitroglycerine at 0.2 and 0.4 μg/kg/min decreased pulmonary arterial wedge pressure (PAWP) and mean pulmonary arterial pressure (PAP) to minimal levels. The final dose of 1 μg/kg/min yielded an ∼20% decrease in mean PAP and pulmonary vascular resistance (PVR).

Discussion

Here, we described the acute effect of intravenous nitroglycerine on PAWP and PVR in a patient with PVOD. This case highlights the venodilation response even in advanced PVOD, suggesting the importance of further research into selective venous dilators as potent therapy.

Pulmonary veno-occlusive disease in childhood-a rare disease not to be missed

Pulmonary veno-occlusive disease (PVOD) is a rare disease leading to pulmonary hypertension and potentially death related to right heart failure and/or respiratory insufficiency. Clinical symptoms are heterogenous and nonspecific: fatigue, decreased exercise tolerance, shortness of breath on exertion, cough, dizziness, chest pain with exercise, palpitations, syncope, as well as nonspecific symptoms such as headache, poor appetite, pallor or perioral cyanosis. Mutations in the EIF2AK4 (eukaryotic translation initiation factor 2-alpha kinase 4) have been recently described, other risk factors include exposure to organic solvent and trichloroethylene, tobacco exposure and chemotherapy. Echocardiography helps to estimate right ventricular systemic pressure, but further diagnostic workup includes cardiac catheterization to confirm pulmonary hypertension and increased pulmonary vascular resistance. High-resolution computed tomography reveals typical findings: centrilobular ground-glass nodules or opacities, septal lines, thickened interlobular septa, mosaic perfusion, and lymphadenopathy. Histology remains the gold standard, but carries risks for the patient. Proper workup is essential in order to avoid incorrect diagnosis. Pulmonary hypertension targeted treatment has been used in patients with PVOD, however, experience is limited, vasodilatory effects on pulmonary vasculature may lead to deterioration of the patients and should be used with great caution. Lung transplantation is currently the only valid treatment option for patients with PVOD. With prolonged waiting time and progression of the disease mechanical support could be considered.

Targeted therapy in pulmonary veno-occlusive disease: time for a rethink?

Background

Pulmonary veno-occlusive disease (PVOD) is a rare condition with poor prognosis, and lung transplantation is recommended as the only curative therapy. The role of pulmonary arterial hypertension targeted therapy in PVOD remains controversial, and long-term effects of targeted therapy have been rarely reported. This study aims to retrospectively evaluate the role of targeted therapy in PVOD patients and the long-term outcome.

Methods

PVOD patients with good responses to targeted therapies were analyzed, and data pre- and post- targeted therapies were compared. An overview of the effects of targeted therapies on PVOD patients was also conducted.

Results

Five genetically or histologically confirmed PVOD patients received targeted therapies and showed good responses. Their mean pulmonary arterial pressure by right heart catheterization was 62.0 ± 11.7 mmHg. Two receiving monotherapy got stabilized, and three receiving sequential combination therapy got improved, cardiac function and exercise capacity significantly improved after treatments. No pulmonary edema occurred. The mean time from the first targeted therapy to the last follow up was 39.3 months, and the longest was 9 years. A systematic review regarding the effects of targeted therapies on PVOD patients indicated majorities of patients got hemodynamics or 6-min walk distance improved, and 26.7% patients developed pulmonary edema. The interval from targeted drugs use to death ranged from 71 min to over 4 years.

Conclusions

Cautious use of targeted therapy could safely and effectively improve or stabilize hemodynamics and exercise capacity of some patients without any complications. PVOD patients could live longer than expected.

Use of vasodilators for the treatment of pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis: A systematic review

BACKGROUND

There are several medications available to treat pulmonary arterial hypertension (PAH): PAH-targeted drugs. However, in patients with pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis (PVOD/PCH), rare diseases that cause pulmonary hypertension, the effectiveness and safety of vasodilators, including PAH-targeted drugs, are unclear.

METHODS

We searched English-language publications listed in three electronic databases (PubMed, Cochrane Library, and the Japan Medical Abstracts Society). Reports with efficacy outcomes (survival, improvement in 6-minute walk distance, and pulmonary vascular resistance) and data on development of pulmonary edema after administration of vasodilators to patients with PVOD/PCH were selected (1966 to August 2015).

RESULTS

We identified 20 reports that met our criteria. No randomized controlled or prospective controlled studies were reported. The survival time ranged from 71 minutes to 4 years or more after initiation of vasodilators. Most of the reported cases showed an improvement in the 6-minute walk distance and pulmonary vascular resistance. Pulmonary edema was reported in 15 articles, some cases of which were lethal.

CONCLUSIONS

The present study demonstrates the potential efficacy and difficulties in the use of vasodilators in patients with PVOD/PCH; however, drawing a firm conclusion was difficult because of the lack of randomized controlled trials. Further research is needed to ascertain if vasodilator use is beneficial and safe in patients with PVOD/PCH.

Pulmonary veno-occlusive disease as a cause of severe pulmonary hypertension in a dog

Background

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary arterial hypertension (PAH) in humans and can be classified in idiopathic, heritable, drug and radiation-induced, and associated with connective tissue disease or human immunodeficiency virus infection. Recently, biallelic mutations of the EIF2AK4 gene have been discovered as a cause for an autosomal recessive form of PVOD in humans. In dogs, PAH is poorly characterized and is generally considered to be idiopathic or secondary to (for example) congenital left-to right cardiovascular shunts or heartworm disease. However, recently, the pathologic features resembling human PVOD were retrospectively described in post-mortem lung samples of dogs presenting with respiratory distress and idiopathic pulmonary hypertension (PH), which suggests that PVOD contributes to an unknown percentage of cases with unexplained PH. In dogs, information on the clinical presentation of PVOD is scarce and the cause and pathogenesis of this disease is still unknown.

Case presentation

An 11-year-old, intact male German Shepherd dog (GSD) was presented with a 2-day history of acute-onset dyspnea and generalized weakness. Physical examination, laboratory analysis, thoracic radiography, echocardiography, a computed tomography scan and an ante mortem lung biopsy demonstrated severe arterial hypoxemia and severe PH but were not diagnostic for a known disease syndrome. Based on the poor reaction to therapy with oxygen, sildenafil, pimobendan and dexamethasone the dog was euthanized. Histopathology of the lungs showed venous and arterial remodelling, segmental congestion of alveolar capillaries and foci of vascular changes similar to human pulmonary capillary hemangiomatosis, indicating that the dog suffered from PVOD. Whole genome sequencing analysis was performed on the case and a healthy GSD. Validation was performed by Sanger sequencing of five additional GSD's unknown for any form of respiratory stress and aged ≥ 10 years. No causal variants were found in the genes that are known to be involved in human PVOD and PAH.

Conclusions

This case report confirms that PVOD should be a diagnostic consideration in dogs presenting with dyspnea and unexplained PH. In the present case, no casual genetic mutations known to be involved in humans with PVOD and PAH were found.

Chronical treatment with sildenafil causes Achilles tendinopathy in rats

AIMS

The primary goal was to assess the effects of chronic sildenafil treatment over the Achilles tendons in rats.

MAIN METHODS

Animals were divided into two groups, control and sildenafil administration (n = 5). After 60 days, the tendons were subject to biochemical and image analysis to compare tendons between the groups: collagen I and decorin content, polarisation microscopy and birefringence analysis, and tissue zymography.

KEY FINDINGS

The animals exposed to sildenafil presented a much less organised tendon matrix, with reduced collagen I and non-collagenous protein content and a much higher decorin content.

SIGNIFICANCE

The results observed in the animals can be characterised as tendinopathy, a condition not yet described as a sildenafil side effect.

Pulmonary veno-occlusive disease: An important consideration in patients with pulmonary hypertension

Pulmonary veno-occlusive disease is a rare subcategory of pulmonary arterial hypertension (WHO Group 1). The disease is poorly understood and difficult to diagnose; it has no definitive cure to date. These patients present with nonspecific symptoms, including dyspnea, exercise intolerance, and weakness. Chest x-rays sometimes differ from idiopathic pulmonary arterial hypertension and may demonstrate alveolar infiltrates and pleural effusions. High resolution computed tomography scans reveal ground glass opacities, interlobular septal thickening, and lymphadenopathy. Echocardiography can estimate the level of pulmonary artery pressures; right heart catheterization is needed for complete hemodynamic characterization of these patients. Lung biopsies demonstrate remodeling of the venules and small veins with intimal and adventitial fibrosis. This can result in total venous occlusion and subsequent recanalization. Similar changes occur in the small arteries and arterioles but are less pronounced than the venous changes. There is no effective medical therapy for these patients, and treatment with the pulmonary arterial hypertension specific medications often causes acute deterioration with pulmonary edema. The recent discovery of the biallelic mutations of the EIF2AK4 gene as an etiology for heritable form of pulmonary veno-occlusive disease increases our understanding of the disease pathogenesis and potentially identifies a future approach to treatment. Without definitive treatment, the prognosis is very poor, and the life expectancy of these patients is much shorter than patients with pulmonary arterial hypertension. These patients need early referral to transplantation centers.

Pulmonary veno-occlusive disease

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension (PH) characterised by preferential remodelling of the pulmonary venules. In the current PH classification, PVOD and pulmonary capillary haemangiomatosis (PCH) are considered to be a common entity and represent varied expressions of the same disease. The recent discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD/PCH represents a major milestone in our understanding of the molecular pathogenesis of PVOD. Although PVOD and pulmonary arterial hypertension (PAH) share a similar clinical presentation, with features of severe precapillary PH, it is important to differentiate these two conditions as PVOD carries a worse prognosis and life-threatening pulmonary oedema may occur following the initiation of PAH therapy. An accurate diagnosis of PVOD based on noninvasive investigations is possible utilising oxygen parameters, low diffusing capacity for carbon monoxide and characteristic signs on high-resolution computed tomography of the chest. No evidence-based medical therapy exists for PVOD at present and lung transplantation remains the preferred definitive therapy for eligible patients.

Pulmonary veno-occlusive disease: an 80-year-old mystery

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension which occurs in 0.1-0.2 people per million. Its etiology is still poorly understood but is related to several risk factors. The histopathology of PVOD is characterized by intimal fibrosis narrowing or the occlusion of small pulmonary veins or venules. A definitive diagnosis requires a surgical biopsy, which is a risky procedure. Thus, the diagnosis must be based on high clinical suspicion and the results of various diagnostic tests, mainly high-resolution computed tomography, pulmonary function tests, bronchoalveolar lavage, and right heart catheterization. The definitive treatment is limited to lung transplantation. Several pulmonary arterial hypertension-specific agents may cause pulmonary edema in PVOD. However, the cautious use of such medications in selected patients, and surgical or mechanical supports, may successfully bridge patients to transplantation. Given the scant knowledge regarding this entity, future studies with a focus on elucidating the etiology and establishing the optimal treatment are required, as is further development in diagnosis.

Pulmonary veno-occlusive disease: the bête noire of pulmonary hypertension in connective tissue diseases?

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension that may develop in patients with connective tissue diseases (CTD). Most cases have been reported in patients with systemic sclerosis, though associations with systemic lupus erythematosis and mixed connective tissue disease have also been described. PVOD is characterised by progressive obstruction of small pulmonary veins and venules that leads to increased pulmonary vascular resistance, right heart failure and premature death. Distinguishing PVOD from pulmonary arterial hypertension (PAH) is often difficult, though use of a diagnostic algorithm may improve diagnostic accuracy and preclude recourse to lung biopsy. The finding of normal left-heart filling pressures in the context of radiological studies suggestive of pulmonary oedema is an important diagnostic clue, particularly if this clinical scenario coincides with the introduction of vasodilator therapy. There are no approved treatments for the disorder, though cautious use of PAH specific therapy may improve short-term outcomes in selected idiopathic PVOD cases. This review summarises the epidemiologic, clinico-pathologic and imaging characteristics of PVOD in the setting of CTD and discusses potential management approaches.

Phosphodiesterase type 5 inhibitors in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterized by vascular proliferation and remodeling, resulting in a progressive increase in pulmonary arterial resistance, right heart failure, and death. The pathogenesis of PAH is multifactorial, with endothelial cell dysfunction playing an integral role. This endothelial dysfunction is characterized by an overproduction of vasoconstrictors and proliferative factors, such as endothelin-1, and a reduction of vasodilators and antiproliferative factors, such prostacyclin and nitric oxide. Phosphodiesterase type 5 (PDE-5) is implicated in this process by inactivating cyclic guanosine monophosphate, the nitric oxide pathway second messenger. PDE-5 is abundantly expressed in lung tissue, and appears to be upregulated in PAH. Three oral PDE-5 inhibitors are available (sildenafil, tadalafil, and vardenafil) and are the recommended first-line treatment for erectile dysfunction. Experimental studies have shown the beneficial effects of PDE-5 inhibitors on pulmonary vascular remodeling and vasodilatation, justifying their investigation in PAH. Randomized clinical trials in monotherapy or combination therapy have been conducted in PAH with sildenafil and tadalafil, which are therefore currently the approved PDE-5 inhibitors in PAH treatment. Sildenafil and tadalafil significantly improve clinical status, exercise capacity, and hemodynamics of PAH patients. Combination therapy of PDE-5 inhibitors with prostacyclin analogs and endothelin receptor antagonists may be helpful in the management of PAH although further studies are needed in this area. The third PDE-5 inhibitor, vardenafil, is currently being investigated in PAH. Side effects are usually mild and transient and include headache, flushing, nasal congestion, digestive disorders, and myalgia. Mild and moderate renal or hepatic failure does not significantly affect the metabolism of PDE-5 inhibitors, whereas coadministration of bosentan decreases sildenafil and tadalafil plasma levels. Due to their clinical effectiveness, tolerance profile, and their oral administration, sildenafil and tadalafil are two of the recommended first-line therapies for PAH patients in World Health Organization functional classes II or III.

Daily Administration of Phosphodiesterase Type 5 Inhibitors for Urological and Nonurological Indications

OBJECTIVES

Although the discovery of phosphodiesterases (PDEs) was made soon after the identification of cyclic adenosine monophosphate nearly half a century ago, their true importance in medicine has taken many decades to be realised. The recognition of the important role PDE enzymes play and the impact of altering intracellular cyclic nucleotide levels became significant for most urologists and clinicians in the early 1990s with the discovery of sildenafil, a PDE5 inhibitor (PDE5-I). Once approved around the world, on-demand use of PDE5-Is became the gold standard. Recently, the potential beneficial effects of PDE5-Is on the pulmonary, vascular, and other systems has led to examination of alternative dosing regimens. In this review, we have synthesised the available published peer-reviewed literature to provide a critical contemporary view of evolving indications for PDE5-Is and how alternative dosing regimens may impact on sexual and other functions.

METHODS

MEDLINE search of all peer-reviewed English literature for the period 1990-2007.

RESULTS

The plethora of articles detailing potential uses of PDE5-I in multiple fields of medicine was uncovered. Use of alternative dosing regimens shows great promise across a number of clinical indications, including post-radical retropubic prostatectomy, pulmonary hypertension, endothelial dysfunction, and salvage of on-demand PDE5-I nonresponders.

CONCLUSIONS

Use of PDE5-I on a daily basis may evolve into a major form of drug administration both for men with erectile dysfunction and for those with a myriad of other conditions shown to benefit from this approach.

Effect of BAY 41-2272 in the pulmonary hypertension induced by heparin-protamine complex in anaesthetized dogs

1. BAY 41-2272 is a potent activator of the nitric oxide-independent site of soluble guanylate cyclase and has been recently introduced as a new therapeutic agent to treat chronic pulmonary hypertension (PH) in neonatal sheep. Because the in vivo heparin-protamine interaction may lead to severe PH, the aim of the present study was to evaluate the effects of BAY 41-2272 in the PH induced by heparin-protamine interaction in anaesthetized dogs. 2. Sixteen male dogs (10 mongrel dogs and six Beagles) were anaesthetized and instrumented for acquisition of mean arterial blood pressure (MABP), mean pulmonary arterial pressure (MPAP), heart rate (HR), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and indices of systemic and pulmonary vascular resistance (ISVR and IPVR, respectively). Plasma cGMP levels and S(p)o(2) were evaluated. 3. Intravenous administration of heparin (500 IU/kg) followed 3 min later by protamine (10 mg/kg) caused marked PH, as evaluated by the increase in MPAP, PCWP and IPVR. This was accompanied by a significant fall in MABP and a transient increase in HR. Infusion of BAY 41-2272 (10 microg/kg per h, starting 10 min before heparin administration) augmented plasma cGMP levels and slightly and significantly increased HR and CI, without affecting the other cardiovascular parameters. The elevation in IPVR, MPAP and PCWP triggered by the heparin-protamine interaction was significantly reduced in animals exposed to BAY 41-2272. 4. In vehicle-treated dogs, the S(p)o(2) values decreased significantly at the peak of the PH and this was significantly attenuated by treatment with BAY 41-2272. In addition, BAY 41-2272 (10 micromol/L) had no effect on the activated partial thromboplastin time of citrated plasma after the addition of heparin-protamine. 5. In conclusion, BAY 41-2272 was effective in reducing canine PH induced in vivo by the heparin-protamine interaction, thus indicating its potential in the treatment of this type of disorder.

Pulmonary Arterial Hypertension

The first description of the circulation of blood through the lungs has been attributed to Ibn Nafis (1210–1288).1 The concept was rediscovered by Michael Servetus, a Spanish physician during the Renaissance (1511–1553) and recorded, oddly enough, in two pages of his religious treatise, Christianismi Restitutio (1553).2 The definitive exposition of the pulmonary circulation was made by William Harvey in DeMotu Cordis (1628).3 The first observation of the pulmonary capillaries was first reported by Marcellus Malpighi (1661).4 Heart catheterization in humans, driven by a desire to obtain the perfect mixed venous specimen and measure cardiac output, was first performed in 1929 by the German urologist Forssmann,5 using a ureteral catheter to access his own right atrium. Over a decade later, Cournand and Richards at Columbia University in New York subsequently used right heart catheterization to record pulmonary artery pressure (PAP) in patients with shock and secondary forms of pulmonary hypertension (PHT). For these accomplishments, which were inspired by an interest in the pulmonary circulation and PHT related to mitral stenosis, Forssmann, Cournand, and Richards received the Nobel Prize in 1956.

The effects of chronic phosphodiesterase-5 inhibitor use on different organ systems

Phosphodiesterase-5 (PDE-5) inhibitors selectively inhibit PDE-5 enzymes that are present in various tissues like penile tissue, platelets, vascular, and smooth muscle tissue. The drug's actions on these tissues have lead to the successful therapeutic use in patients suffering from conditions such as erectile dysfunction (ED) and pulmonary hypertension. PDE-5 inhibitors (PDE-5i) act on the erectile tissue causing penile smooth muscle relaxation and vasodilatation leading to penile erection. In addition, in particular when used in conjunction with prostaglandin inhibitors, PDE-5i cause vasodilatation in pulmonary vasculature hence decreasing both the pulmonary arterial pressure and resistance. PDE-5i have also shown to mildly decrease blood pressure, increase cardiac index, and increase coronary blood flow in experimental animals as well as in human studies. The Food and Drug Administration (FDA) has approved three PDE-5i for the treatment of ED: sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) and one for pulmonary hypertension: sildenafil (Revatio). These agents are highly selective for PDE-5 enzymes as compared to other subclasses of PDE enzymes and have the almost identical pharmacological action but slightly different pharmacokinetics. Only little data exist about long-term use of PDE-5i and their effects on different organ system. This paper reviews the current information available on chronic PDE-5 inhibitor use.