Congenital Heart Interventions

Use of the Medtronic Microvascular Plug 7Q for transcatheter closure of large patent ductus arteriosus in infants weighing less than 2.5 kg. Nasef MA, Sullivan DO, Ng LY, Walsh KP, Oslizlok P, McCrossan B, Kenny D, Sathanandam S. Catheter Cardiovasc Interv. 2022 Apr;99(5):1545-1550. doi: 10.1002/ccd.30105. Epub 2022 Jan 30. PMID: 35094486   Take Home Points: The Medtronic Microvascular Plug (MVP-7Q) is device to consider for use in larger PDAs (4-7 mm) in small premature infants <2.5 kg with good acute success (91% procedural success) and excellent short term follow-up (no LPA, aortic obstruction and no residual shunt) in this limited population of patients. Favorable device characteristics include low profile, flexible delivery cable (and delivery through the diagnostic angled glide catheter. The MVP-7Q device is long (16 mm) which may limit its use in shorter tubular ducts, however the tapered ends and uncovered distal end of the device may allow for some device protrusion into the aorta and LPA without development of significant obstruction. Commentary from Dr. Wendy Whiteside (Ann Arbor, MI, USA), section editor of Congenital Heart Disease Interventions Journal Watch   In this multicenter retrospective review, Nasef et al describe their experience with the use of the Medtronic Microvascular Plug (MVP) 7Q for PDA closure in small premature infants <2.5 kg. While the Amplatzer Piccolo device is the only FDA approved device for PDA closure in preterm infants (>700 grams), there are still a subset of patients with large PDAs with minimum diameter >4 mm for whom Piccolo is too small. Additionally, there are some device/delivery system properties which may make the MVP-7Q an appealing choice for PDA closure in premature infants.   This study included 22 patients from two centers, Children’s Health Ireland at Crumlin and La Bonheur Children’s Hospital in Memphis, TN, with hemodynamically significant PDAs who were less than 2.5kg and had PDA closure attempted with the Medtronic MVP-7Q. The median age at time of procedure was 32 days (IQR 26-57 days) and median weight 1100 grams (IQR 960-1700 grams). MVP-7Q was chosen for PDAs measuring above 4 mm but less than 7 mm (median aortic dimension 5.1 mm, PA dimension 4.8 mm, and length 12 mm). Procedure duration, fluoroscopy time, and radiation dose were all low and on par with Piccolo procedures. Procedural details were also similar to that described with Piccolo, with vascular access exclusively in the femoral vein and retrograde access across the PDA using a 4 French angled glide catheter and Wholey guidewire. As the MVP-7Q can be delivered through the same 4 French catheter, no catheter exchange is necessary.   PDA occlusion was successful in 20/22 patients (91% procedural success). Unsuccessful procedures were 1) failed attempt to implant MVP-7Q via the IJ approach, and 2) significant LPA compression noted during intra-procedural TEE and angiography following device release and necessitating snare/retrieval of the device. There were no other procedural complications noted including vascular access complications, tricuspid valve injury, LPA or aortic stenosis. Post-procedural TTE demonstrated complete occlusion of the PDA in all except one patient, who had small residual shunt through the device which resolved by repeat echo at 7 day follow-up. Median follow-up time was 2.5 years (IQR 12 months-4.3 years) at which time all patients were alive and there was no LPA stenosis, aortic arch obstruction, or residual shunt observed.   Small infants with large PDAs are a difficult population of patients to treat with percutaneous devices. While the Amplatzer Piccolo device is an excellent device for PDA closure in premature infants, it does have some limitations including a stiff delivery system and recommended use in PDAs <4 mm in diameter. The Amplatzer Vascular Plug II (AVPII) can be used for some long tubular PDAs which size out of Piccolo, however it only comes in 2 mm (even number) increments and has a relatively stiff delivery cable which may distort the device. For patients with PDAs in the 4 mm-7 mm range, therefore, there are limited device options. The MVP-7Q is appealing due to its low profile and soft/flexible delivery cable. While the device is long (16 mm unconstrained length, it has an ovoid shape, with contact to the PDA wall over only 8 mm, and an uncovered distal end of the device measuring 4 mm. While this may mean the uncovered tapered distal device or tapered proximal end may extend into the aorta or LPA, respectively, there was minimal concern for LPA or aortic obstruction as a result of the device in immediate and short term follow-up. One additional disadvantage of the MVP-7Q is that it is radio-opaque with the exception of the two device ends, making it a difficult device to visualize during device positioning. Compression of the device can only be appreciated by increased length of the device.   While this study describes only a limited, small sample of patients, it does show feasibility and safety of the use of MVP-7Q for PDA closure in small premature infants. While additional study is necessary in a larger population of patients over a longer follow-up duration, MVP-7Q does provide an alternative device for large PDAs (between ~4-7 mm) in patients <2.5 kg with some nice device characteristics including a low profile, flexible delivery system.  

Prospective multicenter study of the breakable babystent for treatment of aortic coarctation in newborns and infants. Stiller B, Zartner P, Dähnert I, Haas NA, Schubert S, Kanaan M, Berger F, Ewert P, Schmoor C, Grohmann J. Catheter Cardiovasc Interv. 2022 Apr;99(5):1529-1537. doi: 10.1002/ccd.30133. Epub 2022 Feb 16. PMID: 35170186 Clinical Trial.   Take Home Points: The Osypka BabyStent is a 15mm long cobalt chromium stent, premounted on a 6mm balloon and inserted through a 4 French sheath. The stent can be expanded to 10-12mm and with further dilation the locking mechanism of the hook and eye connections opens allowing for further dilation without the need to fracture the stent. The stent was successfully implanted in all patients without access site complications. Commentary from Dr. Konstantin Averin (New York), catheterization section editor of Pediatric Cardiology Journal Watch: Balloon expandable stents (BES) are the mainstay of therapy for many forms of congenital heart disease. In smaller patients, BES use can be limited by the expansion potential of appropriate profile stents. The “holy grail” for congenital interventional cardiologist is a balloon expandable stent that has a low delivery profile, can be implanted at small diameters, and can easily be expanded to adult sizes. In this report, the authors describe the results of a prospective, interventional, open, single-arm, multicenter study from six sites in Germany from 9/2015 to 10/2018 using the breakable Osypka BabyStent (OBS) for treatment of coarctation of the aorta (CoA). OBS is a low profile, 15mm long cobalt-chromium stent, premounted on 6mm balloon and inserted via a 4Fr sheath over a 0.018” wire. The stent easily expands to 10-12mm and after this the locking mechanism of the hook and eye connections opens allowing for further dilation without the need to fracture the stent – see Figure below.   Inclusion criteria were BW > 1.8kg, age < 24 month at time of procedure and isolated aortic or aortic arch obstruction (meeting criteria for stent implant at time of catheterization) deemed high-risk for surgical intervention. Thirty-one patients were screened and subsequently underwent cardiac catheterization; 12 of these did not meet inclusion criteria (10 due to successful balloon dilation and 2 due to lack of consent) – this left 19 patients (median weight 5.6 kg [2.4-8.4] and age 112 days [7-539]). All stents were successfully implanted with the primary endpoint (inner lumen expansion by >50% of baseline diameter) achieved in 15/19 (79%). Most patients required reintervention at 12 months post-stent implant (2 surgical revision and 13 balloon dilation, with 4 requiring a second re-dilation). All patients were alive at 12 month follow up. The two patients requiring surgical revision were due to a post-stent aneurysm at a surgical suture line (implanted 13 days post-surgery) and 1 after stent implant allowed for myocardial recovery with residual gradient. There were no access complications.   The authors describe the successful use of a new stent design that facilitates stent therapy in infants in small children. While not adult capable, these stents convert the relatively chaotic and uncontrolled process of stent fracture into one that is controlled and likely carries less morbidity. Whether this stent proves to be the “holy grail” of stent therapy is not yet clear, but it is certainly an important step-forward in stent design for treatment of congenital heart disease.