Transcatheter closure of patent ductus arteriosus: Past, present and future




Summary


This review aims to describe the past history, present techniques and future directions in transcatheter treatment of patent ductus arteriosus (PDA). Transcatheter PDA closure is the standard of care in most cases and PDA closure is indicated in any patient with signs of left ventricular volume overload due to a ductus. In cases of left-to-right PDA with severe pulmonary arterial hypertension, closure may be performed under specific conditions. The management of clinically silent or very tiny PDAs remains highly controversial. Techniques have evolved and the transcatheter approach to PDA closure is now feasible and safe with current devices. Coils and the Amplatzer Duct Occluder are used most frequently for PDA closure worldwide, with a high occlusion rate and few complications. Transcatheter PDA closure in preterm or low-bodyweight infants remains a highly challenging procedure and further device and catheter design development is indicated before transcatheter closure is the treatment of choice in this delicate patient population. The evolution of transcatheter PDA closure from just 40 years ago with 18 F sheaths to device delivery via a 3 F sheath is remarkable and it is anticipated that further improvements will result in better safety and efficacy of transcatheter PDA closure techniques.


Résumé


L’objectif de cette revue de la littérature est de décrire l’histoire de la fermeture percutanée du canal artériel, ainsi que les techniques actuelles et les perspectives d’avenir. La fermeture percutanée est la méthode de choix dans la grande majorité des cas. Elle est indiquée chez tous les patients ayant des signes de surcharge volumique du ventricule gauche par le shunt artériel. En cas d’hypertension pulmonaire, la fermeture du canal est envisagée à condition que le shunt soit toujours exclusivement gauche-droit et sous certaines conditions. Des controverses perdurent quant à la prise en charge des très petits canaux artériels ou des canaux artériels persistants mais cliniquement silencieux. Les progrès techniques constants réalisés ces dernières années ont rendu cette procédure sûre avec les dispositifs actuels. Les coils et la prothèse d’Amplatz ADO sont actuellement les dispositifs les plus utilisés à travers le monde, avec peu de complications et un fort taux de succès de la procédure. La fermeture percutanée du canal artériel chez les nourrissons prématurés ou de faible poids reste cependant techniquement difficile et le développement de nouveaux matériels miniaturisés reste nécessaire pour considérer l’approche percutanée comme le traitement de première intention dans cette population de patients particulièrement fragiles. Les remarquables évolutions techniques dans la fermeture percutanée du canal artériel depuis 40 ans ont permis de passer progressivement des introducteurs 18 French à du matériel miniaturisé 3 ou 4 French utilisé en pratique quotidienne. Cette dynamique constante permettra à l’avenir d’améliorer encore davantage la faisabilité et la sécurité de cette procédure en toute situation.


Background


Since the first surgical patent ductus arteriosus (PDA) closure by Gross and Hubbard in 1939 and the later transcatheter PDA closure by Portsmann et al. in 1967, there have been many significant developments in the devices used to close a PDA . In the past 20 years, transcatheter closure has become the leading approach to closure of most PDAs . This review aims to describe past history, present techniques and future directions in transcatheter treatment of PDA.


Patent ductus arteriosus


The ductus arteriosus is a vascular structure that connects the left pulmonary artery near its origin to the descending aorta just after the left subclavian artery; it is an essential foetal structure that closes spontaneously in about 90% of full-term infants during the first 48 hours of life. Persistent patency of the PDA beyond a few weeks is considered abnormal and is mainly encountered in neonates with ventilatory or circulatory abnormalities or in premature infants. Formally speaking, PDA is considered a form of congenital heart disease, defined as a persistent patency beyond the third month of life in term infants ; it can be associated with various other congenital heart diseases. In the adult PDA is usually an isolated lesion.


In full-term children, the reported incidence of PDA is approximately 1 per 2000 live births, accounting for 5–10% of all congenital heart diseases . However, addition of the ‘silent’ PDA dramatically increases its incidence to 1 per 500 live births . PDA is a common problem in premature neonates and extremely-low-birthweight infants, being found in 65% of neonates with a birthweight ≤ 1000 g, and is associated with various neonatal morbidities . The female to male ratio is 2:1 in most reports .


Due to several genetic or environmental factors, the ductus may remain patent, causing a left-to-right shunt at the arterial level, pulmonary overcirculation and left heart volume overload. The magnitude of shunting depends on the flow resistance of the ductus and the pressure gradient between aorta and pulmonary arteries. This gradient is dynamic, systolic and diastolic, depending on cardiac output and both systemic and pulmonary vascular resistances . PDA has a broad spectrum of clinical manifestations, varying from asymptomatic heart murmur to congestive heart failure or Eisenmenger’s syndrome. The natural history of the PDA largely depends upon its size, the magnitude of the shunt and the pulmonary vascular resistances. Patients with a moderate left-to-right shunt may remain asymptomatic for years. However, historical series have shown that chronic volume overload may ultimately lead to severe complications, such as congestive heart failure, atrial arrhythmias, irreversible hypertensive pulmonary vascular disease, endarteritis and, rarely, ductus aneurysm or acute aortic dissection .


PDA can be managed by medical, surgical or transcatheter treatment. Non-selective cyclo-oxygenase inhibitors have received the US Food and Drug Administration’s approval for the pharmacological treatment of PDA; their use results in successful PDA closure in 75–93% of cases . However, this efficacy has to be balanced with their significant potential adverse effects on other organ perfusion. Moreover, indications for treatment remain a controversial topic, as 40% of PDAs close spontaneously, even in extremely-low-birthweight neonates. Thus, although efficacious for medical closure of the PDA in the premature infant, a careful assessment of risk/benefit is critical when deciding whether cyclo-oxygenase inhibitors should be used and this decision must be individualized to the particular patient. Guidelines for managing PDA in very-low-birthweight infants have been proposed to clarify this issue . Surgical closure is generally indicated in neonates in whom prostaglandin inhibitors have failed to close the PDA or in cases where prostaglandin inhibitors are contraindicated. The surgical approach consists of PDA ligation or division and is performed via left posterior lateral thoracotomy or, in some experienced hands, by a minimally invasive technique via video-assisted thoracoscopic surgery . In older patients, surgical closure remains the treatment of choice in the rare patients with a ductus too large for device closure or with unsuitable anatomy, such as aneurysmal ductus . In most reports, surgical PDA closure allows a complete closure rate of 94–100% with a 0–2% mortality rate . The most common complications of surgical ductal intervention include pneumothorax, bleeding and recurrent laryngeal nerve injury. Although extremely efficacious and safe for the closure of PDAs, the surgical approach may be associated with greater morbidity and postoperative pain than transcatheter techniques and these factors have been the most common reasons that percutaneous PDA closure has rapidly become the first choice for PDA closure in the appropriate patient.




The past: proof of the concept


PDA was the first congenital heart disease treated by percutaneous intervention. In 1966, Portsmann et al. performed the first transcatheter closure of a PDA without thoracotomy in a 17-year-old boy . The device used was an Ivalon plug, introduced through an 18 F femoral arterial sheath and travelling on a percutaneously laid transductal arteriovenous guide wire. Based on this technique, PDA closure was performed in 197/208 patients (94.7%, age 5–62 years) between 1967 and 1985. The reduced procedural time, lack of need for a thoracotomy and shorter length of hospital stay observed with this approach supported further developments of the procedure . However, the major concern regarding the initial ‘Portsmann plug’ approach was the large size of the arterial delivery sheath, limiting its use in paediatric patients. In 1976, Rashkind et al. developed a transcatheter technique suitable for use in small children, leading to the first successful report 2 years later in an infant weighing 3500 g . The custom-fabricated prototype closure system consisted of a single-foam-disc hooked prosthesis connected to a pin-eye-sleeve attachment-release mechanism. The system was then redesigned and a hookless double-disc system with a pin-eye-sleeve attachment-release mechanism was developed (Rashkind PDA Occluder System). Two polyurethane discs mounted on opposing three- or four-arm spines were assembled, resembling two umbrellas. The first clinical results in 146 patients treated with the Rashkind PDA Occluder System were published in 1987. Successful closure was accomplished in 94 patients (66%), with device embolization in 19 patients (15%) . Although the methods introduced by Portsmann et al. and Rashkind et al. showed advantages over surgical closure, the delivery catheter remained large and bulky, limiting its widespread use. Portsmann’s Ivalon plug required a 13 F to 28 F femoral arterial access and Rashkind’s double-disc device was delivered through an 8 F to 11 F femoral venous access. Additionally and importantly, the success rates for transcatheter PDA closure using these two initial devices were still significantly worse than results reported with the more standard surgical approach.


Sideris et al. developed a self-adjustable PDA device that was modified into a buttoned device that could be delivered through a 7 F sheath. The adjustable length of the loop allowed closure of all types of and large PDAs . Other similar devices, such as the Botallo occluder and the Lock Clamshell device, were developed and transcatheter PDA occlusion became widely available and was used as an alternative to surgery in the early 1990s . These devices were gradually abandoned because of a high incidence of residual leak and subsequent persistent risk of endarteritis, device instability or other major complications . Thus, despite initial widespread enthusiasm, reproducible and safe percutaneous PDA closure proved to be more difficult than initially estimated.


Further research was done to develop a device that could address many of the problems of the earlier devices. Some of the important features that were still not achieved were delivery of the device via a small-sized catheter, repositioning of the device multiple times until ultimately released, retrieval of the device easily if necessary, and the ability to allow for complete closure without causing any aortic or pulmonary artery obstruction or damage . The introduction of embolization coils and the Amplatzer Duct Occluder (ADO, Saint Jude Medical, Minnesota) addressed many of these concerns.


Since the initial reports, the success rates of several techniques of duct closure with embolization coils have continued to improve . The immediate success rate ranged from 75% to 95% and the rate of closure was inversely related to the size of the ductus and dependent on the experience of the operator. Additionally, the coil technique, although inexpensive and feasible via small catheters, was not suitable for all ducts and was associated with a higher than acceptable rate of coil embolization, particularly in the setting of the large ductus.


The ADO was introduced to address many of the deficiencies of coil embolization techniques. It is a self-expandable repositionable mushroom-shaped device made from a 0.004-inch-thick nitinol wire mesh with Dacron patches within. In 1998, Masura et al. reported the initial successful experience with the ADO in 24 patients using an antegrade approach and a transvenous 6 F delivery sheath . Pass et al. later confirmed these results in a multicentre trial in the USA that confirmed the safety and effectiveness of ADO use for transcatheter PDA closure. ADO and coils are currently the preferred technique for catheter closure of PDA worldwide, with most operators using coils for smaller ducts (in which the likelihood of success is great) and the ADO for larger PDAs.




The present: daily practice in the catheterization lab


Transcatheter PDA occlusion has become the treatment of choice for most PDAs in term infants, children and adults . Although age and size are not a consideration when planning surgical closure, transcatheter closure is usually delayed, if feasible, until later in the first year of life, mostly because of the risks of peripheral vascular injury.


Precatheterization care


Most of these patients have no associated structural heart disease. The clinical examination demonstrates the PDA continuous murmur in the expected location. The electrocardiogram is often normal. Active infection is ruled out. Transthoracic echocardiography aims to identify any potential associated lesions, to assess left ventricular volume diameters and function, to assess PDA size and, finally, to assess pulmonary arterial pressure. The echocardiogram is very useful in determining if PDA closure is, in fact, indicated. Although it was previously believed that all PDAs identified should be closed, with more relaxed recommendations regarding subacute bacterial endocarditis prophylaxis in the setting of the ductus, small haemodynamically-insignificant PDAs with no evidence for left atrial or left ventricular enlargement are often not closed.


Angiographical classification


Following a brief assessment of the haemodynamics, PDA closure always begins with an aortogram to precisely assess the aortic arch and PDA characteristics, as the ductus arteriosus may persist in a wide variety of sizes and configurations ( Fig. 1 ). Krichenko et al. described a useful angiographical classification for guidance of transcatheter PDA closure . Ductal anatomy in the lateral projection is classified into five categories: type A is a conical ductus, with a well-defined aortic ampulla and constriction at its pulmonary end; type B is a large and very short ductus, mimicking an aortopulmonary window-like structure; type C is a tubular duct, of varying length, without any constriction at its pulmonary end; type D is more complex, with multiple constrictions on the ductus; type E is an elongated ductus, frequently seen in ex-premature babies. This initial angiography is performed with a 4 F or 5 F pigtail catheter positioned in the proximal descending aorta in the straight lateral view. Other projections may be helpful, such as 30° right anterior oblique projections in the left-sided aortic arch, 30° left anterior oblique projections in the right-sided aortic arch and, eventually, a combined left anterior oblique 30°, cranial 30° to open up the pulmonary artery bifurcation and show the proximal left pulmonary artery (for dextrocardia, it is the right anterior oblique equivalent).




Figure 1


Angiographical classification from Krichenko et al. . Ductal anatomy in the lateral projection is classified into five categories.


Coil occlusion


Coil occlusion is a safe and effective procedure for small PDA closure ( Fig. 2 ). According to the 3:1 principle, the coil is the chosen strategy if the total ductal length is more than three times the narrowest diameter of the PDA . Others have simply used minimal ductal diameter < 1.5–2 mm as an indication for coil implantation, as device implantation in such small PDAs can be challenging. Coils are restricted to small Krichenko type A1 or E PDAs, which constitute the vast majority of PDAs. Residual shunting and coil embolization are more likely to occur if used in shorter ducts or in ducts > 3 mm diameter .


Jul 12, 2017 | Posted by in CARDIOLOGY | Comments Off on Transcatheter closure of patent ductus arteriosus: Past, present and future

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