Atrial septostomy as a bridge to lung transplantation in patients with severe pulmonary hypertension

Review: Therapeutic advances in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries inducing increased pulmonary arterial resistance. Conventional treatment is based on life style modification and nonspecific treatment (warfarine, diuretics, oxygen). Calcium channel blockers are vasodilatators that have been shown to be of great efficacy in a very specific subpopulation of patients with PAH. For the majority of patients, specific PAH therapies are still lacking. Numerous studies evaluating prostacyclin agonists, endothelin-receptor antagonists, and phosphodiesterase type 5 inhibitors are now available to guide therapeutic choices. Despite those important advances there is still no cure for PAH. Fortunately, research is ongoing and many drugs show promises.

The effect of atrial septostomy on the concentration of brain-type natriuretic peptide in patients with idiopathic pulmonary arterial hypertension

Atrial septostomy has improved haemodynamics and clinical symptoms in selected patients with idiopathic pulmonary arterial hypertension. We found that, in 5 patients with idiopathic pulmonary arterial hypertension, septostomy resulted in decreased levels of brain-type natriuretic peptide, and improvement in symptoms of cardiac failure, suggesting that serial measurements of the peptide may have clinical utility.

Management strategies for patients with pulmonary hypertension in the intensive care unit

OBJECTIVE

Pulmonary hypertension may be encountered in the intensive care unit in patients with critical illnesses such as acute respiratory distress syndrome, left ventricular dysfunction, and pulmonary embolism, as well as after cardiothoracic surgery. Pulmonary hypertension also may be encountered in patients with preexisting pulmonary vascular, lung, liver, or cardiac diseases. The intensive care unit management of patients can prove extremely challenging, particularly when they become hemodynamically unstable. The objective of this review is to discuss the pathogenesis and physiology of pulmonary hypertension and the utility of various diagnostic tools, and to provide recommendations regarding the use of vasopressors and pulmonary vasodilators in intensive care.

DATA SOURCES AND EXTRACTION

We undertook a comprehensive review of the literature regarding the management of pulmonary hypertension in the setting of critical illness. We performed a MEDLINE search of articles published from January 1970 to March 2007. Medical subject headings and keywords searched and cross-referenced with each other were: pulmonary hypertension, vasopressor agents, therapeutics, critical illness, intensive care, right ventricular failure, mitral stenosis, prostacyclin, nitric oxide, sildenafil, dopamine, dobutamine, phenylephrine, isoproterenol, and vasopressin. Both human and animal studies related to pulmonary hypertension were reviewed.

CONCLUSIONS

Pulmonary hypertension presents a particular challenge in critically ill patients, because typical therapies such as volume resuscitation and mechanical ventilation may worsen hemodynamics in patients with pulmonary hypertension and right ventricular failure. Patients with decompensated pulmonary hypertension, including those with pulmonary hypertension associated with cardiothoracic surgery, require therapy for right ventricular failure. Very few human studies have addressed the use of vasopressors and pulmonary vasodilators in these patients, but the use of dobutamine, milrinone, inhaled nitric oxide, and intravenous prostacyclin have the greatest support in the literature. Treatment of pulmonary hypertension resulting from critical illness or chronic lung diseases should address the primary cause of hemodynamic deterioration, and pulmonary vasodilators usually are not necessary.

Surgical therapies for pulmonary arterial hypertension

Surgical therapies for the treatment of pulmonary arterial hypertension typically are reserved for patients who are deemed to be refractory to medical therapy and have evidence of progressive right-sided heart failure. Atrial septostomy, a primarily palliative procedure, may stave off hemodynamic collapse from right-sided heart failure long enough to permit a more definitive surgical treatment such as lung or combined heart-lung transplantation. This article discusses indications for and results of atrial septostomy and lung and heart-lung transplantation in patients who have pulmonary arterial hypertension.

Pharmacotherapy for idiopathic pulmonary arterial hypertension during the past 25 years

OBJECTIVE

To review the current pharmacotherapy for idiopathic pulmonary arterial hypertension (IPAH).

METHODS

A search of the primary literature was conducted by using MEDLINE, the National Institutes of Health medical research Web site (www.clinicaltrials.gov), and the United States Food and Drug Administration's Center for Drug Evaluation and Research Web site (www.fda.gov/cder).

RESULTS

Until the early 1980s, conventional therapy for IPAH consisted of anticoagulation, diuretics, digitalis extracts, and supplemental oxygen, yet the 5-year mortality rate remained at 66%. Calcium channel blocker therapy was introduced with the hope that it would improve survival in patients with IPAH, but it was found to be effective in only approximately 25% of patients. In 1996, intravenous epoprostenol was the first drug to show long-term benefit on hemodynamics, exercise capacity, and survival. However, administration of epoprostenol requires a permanently indwelling central venous catheter, and tachyphylaxis is common, necessitating continuous dosage escalations. Subsequently, treprostinil, a prostacyclin analog of epoprostenol that can be administered by continuous subcutaneous infusion, was introduced, followed by aerosolized iloprost, a prostacyclin analog for inhalation. An increasing understanding of the multiple pathogeneses of IPAH led to the discovery of another target for drug therapy, and bosentan, an orally administered agent, became the first endothelin-receptor antagonist approved for treatment of IPAH. Most recently, the phosphodiesterase inhibitor, sildenafil, has received approval from the United States Food and Drug Administration for the treatment of IPAH.

CONCLUSION

Recently developed pharmacotherapies offer greater effectiveness and safety than traditional agents for the treatment of IPAH.

Pulmonary arterial hypertension

Pulmonary arterial hypertension is a disease of the small pulmonary arteries characterized by vascular narrowing and increased pulmonary vascular resistance, which eventually leads to right ventricular failure. Vasoconstriction, vascular proliferation, remodeling of the pulmonary vessels, and thrombosis are all contributing factors to the increased vascular resistance seen in this disease. Pulmonary arterial hypertension develops as a sporadic disease (idiopathic), as an inherited disorder (familial), or in association with certain conditions (collagen vascular diseases, portal hypertension, human immunodeficiency virus infection, congenital systemic-to-pulmonary shunts, ingestion of drugs or dietary products, or persistent fetal circulation). The pathogenesis of pulmonary arterial hypertension is a complicated, multifactorial process. It seems doubtful that any one factor alone is sufficient to activate the necessary pathways leading to the development of this disease. Rather, clinically apparent pulmonary arterial hypertension most likely develops after a second insult occurs in an individual who is already susceptible owing to genetic factors, environmental exposures, or acquired disorders. Currently, there is no cure for pulmonary arterial hypertension but several novel therapeutic options are now available that can improve symptoms and increase survival.

Role of atrial septostomy in the treatment of children with pulmonary arterial hypertension

OBJECTIVES

To assess in retrospect the safety and effectiveness of atrial septostomy in children with severe pulmonary arterial hypertension without an intracardiac communication.

METHODS

20 patients were reviewed retrospectively, 19 with idiopathic pulmonary arterial hypertension. The mean age at septostomy was 8.4 years (range 3 months to 17 years). Graded balloon septostomy alone was carried out in eight patients, a blade septostomy was done in two, a blade septostomy plus graded balloon septostomy was done in three, and a fenestrated device was inserted in seven.

RESULTS

There were no fatalities. Four children suffered complications during the procedure. None had further syncope and all improved symptomatically with a significant (p < 0.01) decrease in World Health Organization functional class (mean shift -0.6) and a significant improvement in the semiquantitative echocardiographic assessment of right ventricular function (p < 0.03). The mean oxygen saturation decreased by 7.8 percentage points. The atrial communication closed in two children, necessitating a repeat procedure. After a mean follow up of 2.1 years (range one month to 6.7 years), 18 of 20 children are still alive.

CONCLUSION

Atrial septostomy improved symptoms and quality of life in a group of children deteriorating with severe pulmonary arterial hypertension. This procedure is to be recommended for severely symptomatic children, before they become critically ill. Fenestrated devices may help ensure indefinite patency of the atrial communication.

Urgent Lung Transplantation in Spain

BACKGROUND

Lung donors are scarce and lung transplantation resources are limited. Because urgent lung transplantation (ULT) is assumed to yield poor results, its use is controversial. We assessed the outcome of patients who received ULT seeking to determine effectiveness and risk factors.

PATIENTS AND METHOD

We collected data from every ULT performed in Spain during 5 years (1998-2002). The survival of patients was studied using Kaplan-Meier, Cox regression, and chi-square statistical analyses. We compared outcomes and perioperative mortality (over 30 days) for ULT procedures, analyzing the influence of certain variables (age, type of transplant, diagnosis, indication, and time on waiting list).

RESULTS

Among 109 patients proposed for the procedure, 73 ULT were performed during the period. The most frequent indications were pulmonary fibrosis (19 cases) and cystic fibrosis (19 cases), showing the worst and the better survival rates, respectively. The bad prognosis, determined mainly by per operative mortality rate (35.62%), was significantly affected by age (worse for patients older than 40 years) and type of LT (single worse than double; P < .05). A longer time waiting for ULT also showed a worse prognosis (P < .005).

CONCLUSIONS

Long-term survival after ULT shows that the procedure is effective and efficient for a select group of patients, despite the high per operative risk. ULT should be reserved for younger patients. It also requires performance in a short period (just a few days), initially rejecting a single lung transplant, provided that the patient is adequately monitored.

Traitement de l’hypertension artérielle pulmonaire

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries. It induces a fixed pulmonary arterial obstruction, persistent elevation of pulmonary arterial resistance, and eventually right heart failure. Conventional therapy is based on simple measures (exercise limitation) and nonspecific treatments (warfarin, diuretics, and oxygen). Pure vasodilators, such as calcium channel blockers, are effective only in a minority of patients who have an acute response to vasodilator testing. Intravenous prostacyclin (epoprostenol) and endothelin receptor blockers have vasodilator and antiproliferative properties. Epoprostenol therapy has significantly improved PAH prognosis and remains the first-line treatment for patients with the most severe disease. Bosentan is an interesting first-line treatment for NYHA functional class III patients. Availability of novel specific drugs (endothelin receptor type A antagonists, prostacyclin analogues, type 5 phosphodiesterase inhibitors) is opening new perspectives in PAH treatment. The long-term benefit of these drugs remains to be evaluated and their respective place in treatment of these patients is still uncertain. The evolution of therapy from vasodilators to antiproliferative agents reflects the advancement in our understanding of the mechanisms mediating pulmonary arterial hypertension.

Creation and enlargement of atrial defects in congenital heart disease

Transcatheter creation and enlargement of interatrial defects (IAD) may improve hemodynamics; however, procedural outcomes have not been well defined. Hospital records were reviewed for children who underwent percutaneous procedures to create and enlarge an IAD and were grouped as follows: (1) right and (2) left heart obstructive lesions, (3) left atrial (LA) decompression during left heart assist, (4) failing Fontan circulation, and (5) miscellaneous. Forty-five children (mean age, 3.4 +/- 4.7 years; 30 (67%) male) were identified. In group 1 (n = 6), all achieved endpoints of right atrial (RA) decompression (n = 2), improved left ventricular filling (n = 3), or improved arterial saturations (n = 1). In group 2 (n = 18), mean LA pressure decreased (21 +/- 6 to 13 +/- 5 mmHg, p < 0.001) and arterial saturations increased (61 +/- 13% to 78 +/- 11%, p < 0.001). All except 2 patients achieved definitive repair, further palliation (n = 9), or heart transplantation (HTX) (n = 7). In group 3 (n = 5), the LA was decompressed (21 to 13 mmHg, p = 0.03) in all, and all except 1 patient survived to HTX (n = 2) or full recovery (n = 2). In group 4 (n = 11), of 7 patients with a low cardiac output syndrome after surgery, despite improved atrial shunting, 3 died and 1 required a HTX. In group 5 (n = 5), RA decompression (n = 1) or improved arterial saturation (n = 4) was achieved in all. Overall, 5-year HTX free survival was 75%. Mechanical ventilation before the procedure (p < 0.001), the need for a blade septostomy (p = 0.002), and higher LA pressures after the procedure (p = 0.04) independently predicted mortality or the requirement for HTX. Transcatheter optimization of an atrial communication can help optimize treatment strategies and has a low procedural risk.

The right ventricle in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a term used to classify a variety of conditions that share in common an injury to the pulmonary vasculature that produces elevations in pulmonary arterial pressure. However, it is the integrity of right ventricular function, rather than the degree of vascular injury, that is the major determinant of symptoms and survival in PAH. The article will review the normal structure and function of the right ventricle and summarize the impact of PAH and its treatments on right ventricular function.

[Treatments for pulmonary arterial hypertension]

PURPOSE

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis and vascular remodeling of small pulmonary arteries inducing a fixed pulmonary arterial obstruction and persistent elevation of pulmonary arterial resistance. Conventional treatment is based on simple measures (exercise limitation) and non-specific drugs (warfarine, diuretics, oxygen).

CURRENT KNOWLEDGE AND KEY POINTS

Pure vasodilators like calcium channel antagonists have little or no effect on the vast majority of patients, presumably because fixed pulmonary arteriopathy predominate over vasoconstriction. Intravenous prostacyclin (epoprostenol) and endothelin receptor antagonists have vasodilator and antiproliferative properties. Epoprostenol therapy has resulted in significant improvements in prognosis of this disease and this drug remains the first-line treatment of the most severe patients. Bosentan is an interesting first-line treatment for NYHA functional class III patients. Availability of novel specific drugs (endothelin receptor type A antagonists, prostacyclin analogues, type 5 phosphodiesterase inhibitors) open new perspectives in treatment of PAH. The long-term benefit of these drugs remains to be evaluated and their respective place in treatment of these patients is still uncertain. We here present the different therapeutic alternatives available in the PAH and propose an algorithm for treatment of these patients.

FUTURE PROSPECTS AND PROJECTS

The evolution of therapy from vasodilators to antiproliferative agents reflects the advancement in our understanding of the mechanisms mediating pulmonary arterial hypertension.

Interventional and surgical modalities of treatment for pulmonary arterial hypertension

Beyond medical therapy, different interventional and surgical approaches exist for treatment of pulmonary arterial hypertension (PAH). Atrial septostomy has been applied in patients with lack of response to medical therapy in the absence of other surgical treatment options. With growing experience, procedure-related death rates have been reduced to 5.4%, and the most suitable patient group has been identified among patients with a mean right atrial pressure between 10 and 20 mm Hg. Pulmonary endarterectomy is the accepted form of treatment for patients with chronic thromboembolic pulmonary hypertension. Establishing the diagnosis and the classification of the type of lesions by pulmonary angiography is crucial for optimal patient selection. Perioperative mortality rates have been reduced to <10% in experienced centers, and the hemodynamic improvement is dramatic and sustained. Lung and heart-lung transplantation remains the procedure of choice for patients unsuitable for other treatment modalities. Timing of the procedure is difficult because waiting times vary between centers and usually are in a high range. Early referral of patients unresponsive to other treatment forms is therefore of importance to avoid transplantation of patients with established significant comorbidity. The survival rate during the first five years after transplantation for PAH is intermediate among the lung diseases, lower than chronic obstructive pulmonary disease but higher than idiopathic pulmonary fibrosis.

Modified technique of stent fenestration of the atrial septum

OBJECTIVES

To develop a modified technique for stenting the atrial septum in the treatment of patients with a failing Fontan operation or pulmonary hypertension.

SETTING

Two tertiary referral centres.

STUDY DESIGN

Prospective collaborative clinical study.

PATIENTS AND METHODS

A stent was mounted on a standard valvoplasty balloon catheter which was constricted to a predefined diameter by a loop created from a temporary pacing wire. Full balloon inflation created a diabolo shaped stent configuration. The technique was employed in 12 consecutive patients to relieve symptoms of a failing Fontan circulation (n = 6) or severe pulmonary hypertension (n = 6).

RESULTS

Ex vivo studies confirmed that a diabolo shaped stent configuration could be achieved using the above technique. Transcatheter stent implantation was successful in all 12 patients. All six Fontan patients showed significant clinical improvement. Right atrial pressure decreased from (mean (SD)) 16.8 (2.5) to 13.7 (1.9) mm Hg (p < 0.05), and arterial oxygen saturation from 92.8 (1.8)% to 82.7 (3.8)% (p < 0.01). Six patients underwent successful stent fenestration for treatment of pulmonary hypertension. All stents were patent and stable at the most recent follow up (mean 1.75 (1.05) years). No early or late stent related complications were encountered.

CONCLUSIONS

This new technique allows placement of a diabolo shaped stent with a predefined diameter across the atrial septum. The diabolo shape increases stent stability, facilitates recrossing of the stent during future catheter interventions, and ensures medium term stent patency.

Atrial septostomy in the treatment of severe pulmonary arterial hypertension

BACKGROUND

Atrial septostomy (AS) may improve symptoms and haemodynamics in patients with severe pulmonary arterial hypertension (PAH).

METHODS

Twenty AS performed in 17 patients with severe progressive PAH (13 primary pulmonary hypertension, two collagen vascular disease, one thromboembolic disease, one vaso-occlusive disease) were analysed. Seven patients were in NYHA class III and 10 in NYHA IV. Fifteen patients were on long term prostanoid treatment. AS was performed under fluoroscopy using graded balloon technique.

RESULTS

AS improved clinical symptoms and increased the cardiac index from 1.8 to 2.2 l/min/m(2) and systemic oxygen transport from 263.2 to 329.6 ml/min/m(2) (p<0.001). Procedure related complications included one non-fatal atrial puncture and one unsuccessful septal puncture. Four patients died within 1 week of surgery from uncontrolled tachyarrhythmia (n=1), severe hypoxaemia (n=1), and multiorgan failure (n=2). One further patient died after voluntarily discontinuing renal dialysis. Twelve patients are alive 5-17 months after the operation with five patients undergoing heart-lung transplantation. There were no differences in haemodynamic and functional parameters between the non-survivors and the mid term survivors. However, the non-survivors were significantly older (52 v 36 years, p<0.01) and had a significantly lower creatinine clearance rate (70 ml/min v 48 ml/min, p<0.05).

CONCLUSION

Atrial septostomy improves clinical symptoms, cardiac index, and systemic oxygen transport and has the potential to influence the prognosis in selected cases of severe PAH.

Recipient selection

Since international recommendations for lung transplant recipients were made in 1998, newer tools for predicting mortality in patients who have end-stage lung disease have been investigated. This article reviews studies for predicting mortality in obstructive, restrictive, pulmonary vascular, and suppurative/bronchiectatic lung disease. Newer considerations for alternative treatments, postoperative risks, and contraindications are also examined. The article aims to provide more accurate data for selecting patients who will benefit from lung transplantation.

The pulmonary physician in critical care. 13: the pulmonary circulation and right ventricular failure in the ITU

The management of severe pulmonary hypertension associated with right ventricular failure is reviewed and its relevance to adults with acute respiratory distress syndrome (ARDS) is discussed.

Atrial septostomy for pulmonary hypertension

Atrial septostomy represents an additional, promising strategy in the treatment of severe PPH. Experience with this procedure still is limited; however, based on analyses of the worldwide experience, several general conclusions and recommendations can be made. 1. Atrial septostomy can be performed successfully in selected patients with advanced pulmonary vascular disease. 2. Patients with primary pulmonary hypertension who have undergone successful AS have shown: a significant clinical improvement beneficial and long-lasting hemodynamic effects at rest a trend toward improved survival 3. The procedure-related mortality of the collective experience is high (16%). Several recommendations can be made to minimize the risk: [figure: see text] Atrial septostomy should be attempted only in institutions with an established track record in the treatment of advanced pulmonary hypertension, where septostomy is performed with low morbidity. Atrial septostomy should not be performed in patients in whom death is impending or who have severe right ventricular failure and are on maximal cardiorespiratory support. An mRAP greater than 20 mm Hg, PVR index greater than 55 u/m2, and a predicted 1-year survival less than 40% are significant predictors of procedure-related death. Before cardiac catheterization, patients should have an acceptable baseline systemic oxygen saturation (> 90% in room air) and optimized cardiac function (adequate right heart filling pressure, additional inotropic support if necessary). During cardiac catheterization, the following are mandatory: Supplemental oxygen Mild sedation to prevent anxiety Careful monitoring of variables (left atrial pressure, SaO2, and mRAP) Step by step procedure After AS, it is important to optimize oxygen delivery. Transfusion of packed red blood cells or erythropoietin (before and following the procedure, if needed) may be necessary to increase oxygen content. 4. Because the disease process in PPH is unaffected by the procedure (late deaths), the long-term effects of an AS must be considered to be palliative. 5. Despite its risk, AS may represent a viable alternative for selected patients with severe PPH. Indications for the procedure may include: Recurrent syncope or right ventricular failure, despite maximal medical therapy, including oral calcium-channel blockers or continuous intravenous prostacyclin (Fig. 11) As a bridge to transplantation When no other option exists.

Balloon atrial septostomy in end-stage pulmonary hypertension guided by a novel intracardiac echocardiographic transducer

Blade and balloon atrial septostomy has been used to reduce cardiopulmonary symptoms and as a bridge to lung or heart lung transplant in primary pulmonary hypertension. Due to severe right atrial dilatation and resultant loss of anatomical landmarks, the procedure is technically difficult, and the reported postprocedure mortality rate varies between 5% and 50%. Among others, marked systemic desaturation and systemic hypotension presumably secondary to an excessively large atrial septal defect have been reported as causes of postprocedure death. We report a case where a novel intracardiac catheter-based phased-array 5.5--10 MHz transducer with spectral and color-flow Doppler capabilities was used to assist a balloon atrial septostomy and to obtain hemodynamic data in a patient with end-stage pulmonary hypertension.

Secondary Pulmonary Hypertension

The diagnosis of pulmonary hypertension first requires a clinical suspicion, as symptoms are often nonspecific. After the diagnosis is made, appropriate classification into the various categories of pulmonary hypertension is essential in order to manage the patient's disease and symptoms appropriately. Therapy is targeted at the underlying cause of the pulmonary hypertension, as well as its effects on the cardiovascular system. Until recently, the treatment of both primary and secondary pulmonary arterial hypertension was limited to supportive therapy alone. With the advent of novel therapeutic agents, more focused therapies designed to treat the pulmonary vasculopathy have become available. These include pulmonary vasodilators such as continuous intravenous prostacyclin, and experimental agents currently undergoing clinical trials. For patients with pulmonary hypertension secondary to pulmonary venous hypertension, therapies differ. In cases where there is left-sided heart disease leading to pulmonary venous hypertension, treatment is aimed at repairing or ameliorating the underlying heart disease. Patients with pulmonary venous hypertension due to extrinsic compression of the central pulmonary veins, or pulmonary veno-occlusive disease have few options, and treatment is generally palliative. In patients with pulmonary hypertension that is associated with disorders of the respiratory system or hypoxemia, the pulmonary hypertension is due to a reactive pulmonary vasoconstriction. Reversal of this vasoconstriction with pulmonary vasodilators can be harmful because of the risk of increasing perfusion to nonventilated lung units. Pulmonary hypertension due to chronic thrombotic or embolic disease can be treated surgically, if the obstructive thrombi are proximal enough for the surgeon to resect them. More distal pulmonary emboli, however, cannot be resected, but there is emerging evidence that the chronic administration of pulmonary vasodilators can be effective in treating this form of the disease.

Current management of patients with pulmonary hypertension and right ventricular insufficiency

Pulmonary hypertension is a pathologic condition characterized by elevated pulmonary artery pressures and an associated vasculopathy. Primary pulmonary hypertension (PPH) is a rare condition with a sporadic occurrence and a familial form of the disorder. Abnormal vasomotor tone in the pulmonary vasculature results from an imbalance of the action of various vasoconstrictors/ vascular proliferative agents (endothelin and thromboxane) versus vasodilators /anti-proliferative agents (prostacyclin and nitric oxide). The mainstay of outpatient therapy has been the use of digitalis, diuretics, oxygen, and coumadin and the judicious use of vasodilator therapy. Calcium channel blockers in a select group and intravenous prostacyclin have dramatically improved survival for those with primary pulmonary hypertension. Use of prostaglandin I2 (PGI2) in other forms of chronic pulmonary arterial hypertension is not as clear, although evidence of initial beneficial response is promising. Importantly, over the next few years both pharmacologic and nonpharmacologic treatment modalities for pulmonary hypertension may rapidly change as we focus more on the abnormal pulmonary vascular biology and concomitant hemodynamic and neurohormonal milieu.