Journal of Veterinary Cardiology (2019) 21,41e48

www.elsevier.com/locate/jvc

Case Report Stent angioplasty for treatment of canine valvular pulmonic stenosis*,**

I. Sosa, DVM a, S.T. Swift, DVM a,*, A.E. Jones, DVM a, A.H. Estrada, DVM a, J.C. Fudge, MD b a Department of Small Animal Clinical Sciences, University of Florida, College of Veterinary Medicine, Gainesville, FL, 32608, USA b Congenital Heart Center, 1600 SW Archer Rd, Gainesville, FL, 32610, USA

Received 10 March 2018; received in revised form 24 October 2018; accepted 26 October 2018

KEYWORDS Abstract Four dogs presented for evaluation and treatment of severe pulmonic Nitinol; valve stenosis and underwent stenting of the pulmonic valve annulus using bare-me- Dogs; tal balloon-expandable stents. All dogs survived the procedure with immediate re- Congenital heart dis- duction of the transpulmonary valve pressure gradient and increase in activity ease; levels. One dog had a stent fracture and migration 1 month after the intervention. Valvuloplasty This dog underwent a second procedure, in which multiple stents were used to alle- viate the obstruction. The stents that were placed at the level of the right ventricular outflow tract fractured within 1 month of the procedure, and the patient died when a third (surgical) approach was attempted. The other three dogs remain alive 54, 42, and 29 months after the procedure. Stent angioplasty may be a viable option for dogs with valvular pulmonic stenosis in which routine balloon valvuloplasty does not

* A unique aspect of the Journal of Veterinary Cardiology is the emphasis of additional web-based images permitting the detailing of procedures and diagnostics. These images can be viewed (by those readers with subscription access) by going to http://www. sciencedirect.com/science/journal/17602734. The issue to be viewed is clicked and the available PDF and image downloading is available via the Summary Plus link. The supplementary material for a given article appears at the end of the page. Downloading the videos may take several minutes. Readers will require at least Quicktime 7 (available free at http://www.apple.com/quicktime/ download/) to enjoy the content. Another means to view the material is to go to http://www.doi.org and enter the doi number unique to this paper which is indicated at the end of the manuscript. ** A unique aspect of the Journal of Veterinary Cardiology is the emphasis of additional web-based materials permitting the detailing of procedures and diagnostics. These materials can be viewed (by those readers with subscription access) by going to http://www.sciencedirect.com/science/journal/17602734. The issue to be viewed is clicked and the available PDF and image downloading is available via the Summary Plus link. The supplementary material for a given article appears at the end of the page. To view the material is to go to http://www.doi.org and enter the doi number unique to this paper which is indicated at the end of the manuscript. * Corresponding author. E-mail address: sswift@ufl.edu (S.T. Swift). https://doi.org/10.1016/j.jvc.2018.10.007 1760-2734/Published by Elsevier B.V. 42 I. Sosa et al.

provide a successful outcome. Aggressive attempts to diminish RVOT dynamic ob- struction with high-dose beta blockade and avoiding deployment of the stent within the RVOT are recommended to prevent stent fracture and migration. Published by Elsevier B.V.

this thickening appeared to create a dynamic Abbreviations subvalvular stenosis. Atenolol was initiated orally at 0.5 mg/kg every 12 h and titrated up to ATM atmospheres 2.4 mg/kg every 12 h based on intermittent heart BV balloon valvuloplasty rate checks. The patient returned 1 month later BIB balloon-in-balloon with a resting heart rate of 60 beats per minute. CTD cor triatriatum dexter The second echocardiogram showed a reduction PG pressure gradient of the dynamic subvalvular obstruction but no PHT pressure half-time change on the overall transpulmonary systolic PG PS pulmonic stenosis (Figs. I and II available in Supplementary Materials RBP rated burst pressure online). Owing to the severe dysplastic pulmonic RVOT right ventricular outflow tract leaflets, there was concern that balloon valvulo- plasty (BV) would not decrease the PG sig- nificantly. Consequently, we elected to stent the pulmonic valve. There was concern that the con- Case 1 centric hypertrophy of the right ventricle could result in stent fracture, but as the dynamic A 4-month-old 11-kg male Labrador retriever obstruction had been well controlled by beta mixed dog from a rescue shelter presented to the blockers, this was felt to be less unlikely (see Small Animal Hospital at the University of Florida Table 1). for evaluation of a heart murmur. The dog was The dog was anesthetized the following day. asymptomatic on presentation. Physical examina- The left femoral artery was catheterized, and tion revealed a grade V/VI systolic heart murmur angiography of the aortic root using a 5-Fr pigtail at the left base. Echocardiography showed severe catheterc showed normal coronary anatomy. Right right ventricular concentric hypertrophy with heart catheterization was performed through the flattening of the interventricular septum in sys- right external jugular vein as previously described tole and diastole (Video 1). Pulmonic valve leaf- [1]. The pullback peak-to-peak PG between the lets appeared severely dysplastic with a pulmonic right ventricle and pulmonary artery was valve annulus diameter of 12.2 mm (aortic valve 46 mmHg. Right ventriculography was performed annulus of 15.6 mm). Continuous wave Doppler through a 5-Fr NIH angiographic catheterc, and the interrogation across the pulmonic valve showed a pulmonary artery annulus diameter was measured peak systolic velocity of 5.58 m/s, reflecting an in systole and diastole (Video 2). The pulmonic instantaneous transpulmonary systolic pressure stenosis (PS) and dynamic RVOT compression could gradient (PG) of 124.8 mmHg, consistent with be visualized. In addition, the distance between severe pulmonic valve stenosis. There was mild the RVOT and the main pulmonary artery segment pulmonic insufficiency (pressure half-time [PHT] corresponding to the desired stent implantation 551 ms). Coronary artery anatomy appeared nor- site was measured to ensure the appropriate stent mal. Severe thickening of the right ventricular size was chosen. A Tyshak 20-mm by 4-cm balloond outflow tract (RVOT) was evident, and based on was used to perform balloon sizing of the pulmo- two-dimensional and spectral Doppler tracing, nary valve obstruction. This allowed us to confirm both the diameter and the anatomic location of Table 1 Summary of the peak systolic pressure the obstruction, which is important in choosing the gradients in mmHg. balloon diameter used to implant the stent and provide confirmation of the desired stent implan- Case number Pre-stent 24 h post Longer term tation site. Manual inflation of the balloon showed stent follow up Case 1 125 60 55 at 36 months Case 2 151 29 70 at 42 months Case 3 160 60 N/A c Cook Medical. Bloomington, IN 47402-0489, USA. d Case 4 120 26 26 at 6 month Braun Interventional Systems Inc, Allentown, PA, 18109, USA. Stent angioplasty for pulmonic stenosis. 43 a waist that measured 12 mm in diameter. A Cordis and through the sheath to the desired implantation Palmaz XL 29-mm by 10-mm transhepatic biliary site. The delivery sheath was withdrawn into the stente was mounted on a 20-mm  4-cm balloon- right ventricle uncovering the stent. A hand in-balloonf (BIB) catheter. The stent was mounted injection of contrast was performed to confirm by placing it on the balloon and hand crimping it proper positioning of the stent, and then, the inner followed by further crimping using a piece of flat balloon was inflated maximally to 10-mm diameter 1/8 inch umbilical tapeg (Fig. III available in Sup- to partially expand the stent. Minimal adjustments plementary Materials online). The umbilical tape were made to achieve the optimal stent position, was soaked in contrasth and wrapped once cir- and then, the outer balloon was inflated to fully cumferentially around the stent. It was then deploy the stent at a rated burst pressure (RBP) of sequentially tightened along the length of the 5 atmospheres (ATM) using a balloon inflation stent beginning in the middle. The umbilical tape deviced. The balloon and delivery sheath were was then removed. The BIB system is beneficial removed. Repeat hemodynamics demonstrated a because it contains a smaller inner balloon which, peak-to-peak pullback gradient of 6 mmHg when inflated, may allow for more precise posi- between the right ventricle and pulmonary artery. tioning of the stent before full deployment. Once The introducer was removed, and the femoral vein the position of the stent is optimized, the bigger was ligated without complications. Dalteparin (150 outer balloon is inflated to expand the stent fully. units/kg once) and cefazolin (22 mg/kg IV every A balloon wedge pressure catheteri was advanced 90 min) were administered intravenously through- into the pulmonary artery and a 0.035” 260 cm out the procedure. After recovery, aspirin at 5 mg/ Amplatz Super Stiff guidewirej advanced along it. kg and a loading dose of 10 mg/kg of clopidogrel The balloon wedge pressure catheter and the 9-Fr were given. Antibiotic therapy was continued for 2 short introducerc were removed from the external weeks (cephalexin 30 mg/kg q 12 h orally), and jugular vein, leaving the guidewire in position. A prophylactic anticoagulation provided by clopi- 12-Fr 75-cm Check-Flo Performer introducer dogrel (1 mg/kg q 24 h) and aspirin (5 mg/kg q sheathc with dilator was advanced over the 24 h) was continued for 6 months. guidewire across the stenosis and the dilator was An echocardiogram was performed 24 h after removed. The BIB balloon and mounted stent were stent placement, showing the stent successfully advanced over the guidewire into the introducer deployed across the pulmonic valve (Video 1). The sheath. Unfortunately, the stent could not be systolic PG using continuous wave Doppler was advanced past a kink that had developed in the 60 mmHg, with pulmonic regurgitation (PHT of sheath as the sheath took a turn in the right ven- 147 ms, Fig. IV available in Supplementary Mate- tricle to the RVOT. The BIB catheter and stent rials online). The patient was discharged with a were removed followed by the sheath and guide- lower dose of atenolol (1 mg/kg q 12 h). One wire. The jugular vein was ligated with 3.0 PDSk, month later, the PG across the stent was 35 mmHg, and left femoral venous access was obtained as the and it gradually increased to 55 mmHg over the dog was lying in left lateral recumbency using a 9- next 36 months. The dog remains alive and Fr introducerc. The balloon wedge pressure cath- asymptomatic at the time of writing this article (54 eteri was used once again to position the Amplatz months after procedure). Super Stiff guidewirej in the distal branch pulmo- nary artery. The 9-Fr introducer was removed, and a new 11-Fr 85-cm Super Arrow-Flex introducerl Case 2 sheath with dilator was then advanced over the wire to a position across the pulmonary obstruc- A 5-month-old 5.3-kg male French bulldog dog tion, and the dilator was removed. The previously presented to the Small Animal Hospital at the mounted stent was advanced over the guidewire University of Florida for evaluation of a heart murmur. The dog had mild exercise intolerance. Physical examination revealed a grade IV/VI sys- tolic heart murmur at the left base. Echocardiog- e Cordis. Lindenstrasse, 10 6340 Baar, Switzerland. f NuMed, Inc. Hopkinton, NY 12965, USA. raphy showed severe right ventricular concentric g Jorgensen Laboratories Inc Loveland, CO 80538, USA. hypertrophy, and the pulmonic valve leaflets h Omnipaque 300 mg/mL, GE Healthcare, Marlborough, MA appeared severely dysplastic with a pulmonic 01752, USA. valve annulus of 7 mm (aortic valve annulus of i Arrow International Inc, Reading, PA 19005, USA. 10 mm). Continuous wave Doppler across the pul- j Boston Scientific, Marlborough, MA 01752, USA. k Ethicon Inc. Somerville, NJ 08876, USA. monic valve showed a peak systolic velocity of l Teleflex Medical Wayne, PA 19087, USA. 5.62 m/s, reflecting an instantaneous systolic PG of 44 I. Sosa et al.

126 mmHg, consistent with severe pulmonic valve Case 3 stenosis. Atenolol was started at 0.5 mg/kg every 12 h titrated up to 1.5 mg/kg every 12 h to try to A 5-month-old 12.1-kg spayed female, mixed control the heart rate and reduce any dynamic breed dog presented from a rescue shelter organ- obstruction as in case 1. One month later, an echo- ization to the Small Animal Hospital at the Uni- cardiogram showed a PG across the stenosis of versity of Florida for evaluation of a heart murmur. 151 mmHg. During BV, the levo phase of the right The patient was asymptomatic at presentation. ventricular angiography demonstrated normal cor- Echocardiogram revealed valvular PS with fused onary artery anatomy. Dilation was attempted using and dysplastic leaflets and an echo-derived f a 10-mm by 3-cm Marauder balloon (RBP 20 ATM) instantaneous systolic PG of 155 mmHg. Balloon but did not change the PG 24 h after the procedure. valvuloplasty was performed with a 16-mm by 4- e A Cordis Palmaz Genesis 28-mm by 10-mm stent cm Tyshak II balloond (RBP 2.5 ATM) and was was placed across the pulmonic valve 2 weeks unsuccessful, with an echo-derived instantaneous later in the same manner as in case 1. Owing to the systolic PG of 133 mmHg 24 h after the procedure. small patient’s size, a 10-mm  2-cm Mustang bal- One year later with the patient weighing 23.3 kg, j loon was used to deploy the stent instead of a BIB an echocardiogram showed that the PG had catheter as the smallest diameter BIB catheter is increased to 160 mmHg. A Cordis Palmaz XL 29 mm 12 mm (Video 3). The echo-derived systolic instan- by 10 mm transhepatic biliary stente was then taneous PG across the stenosis 24 h after placing the implanted across the pulmonary valve as in case 1. stent was 29 mmHg. The patient also had pulmonary Twenty-four hours after stent implantation, an insufficiency with a PHT of 66 ms. At discharge, the echocardiogram showed an RVOT systolic PG of patient was continued on atenolol (0.5 mg/kg q 60 mmHg and pulmonic regurgitation (PHT 12 h) and started on antibiotics and anticoagulants 150 ms). At discharge, the patient was continued as in case 1. Regular echocardiograms showed a on atenolol (0.5 mg/kg q 12 h) and started on gradual increase in the PG of up to 70 mmHg at the antibiotics and anticoagulants as in case 1. One time of writing this article. The dog is currently alive month later, a recheck echocardiogram showed and remains asymptomatic 42 months after the migration of the stent more distally into the pul- procedure. monary artery and persistent PS with a systolic PG

Fig. 1 Right lateral thoracic radiograph of case 3 showing stent fracture and migration toward the left pulmonary artery. Stent angioplasty for pulmonic stenosis. 45

Fig. 2 Right lateral thoracic radiograph of case 3 showing fracture of multiple stents. Stent debris migrated throughout the pulmonary vasculature. of 160 mmHg. Thoracic radiographs showed a and pulmonary artery stenosis. Postoperative fracture of the proximal edge of the stent and a thoracic radiographs and echocardiogram showed an displaced fragment further out in the pulmonary echo-derived systolic gradient of 36 mmHg across artery (Fig. 1). A second stent implantation proce- the RVOT. One month later, thoracic radiographs dure was planned. The first stent was flared prox- revealed fracture of the stents with migration of the imally using a 14-mm by 4-cm Tyshak II balloond to fragments into the pulmonary arteries (Fig. 2). The better accommodate the distal section of the second patient was referred to Colorado State University for stent and allow the stents to overlap (Video 4). The evaluation and possible surgical intervention. The second Cordis Palmaz XL 39-mm by 10-mm stente dog died during an attempt to place a conduit barely spanned the obstruction so a third Cordis between the right ventricle and pulmonary artery to Palmaz XL 29-mm by 10-mm stente was deployed. bypass the obstruction. Compression of the third stent in the RVOT was seen during systole so a fourth Genesis 28-mm by 8-mm stente was used. Unfortunately, during deployment Case 4 of the fourth stent, the stent did not expand to the desired diameter and was unstable. Attempts to A 2-month-old 5.6-kg female mixed breed dog was change the stent’s conformation with a high pres- referred for an evaluation of PS and perforate cor m sure 18-mm by 2-cm Atlas Gold balloon (RBP 16 triatriatum dexter (CTD). There was marked ATM) were unsuccessful, so a fifth Cordis Palmaz XL ascites on presentation. The echocardiogram e 29-mm by 10-mm stent was used to stabilize that showed a systolic PG across the pulmonary valve of stent. The 12-Fr 75-cm Check-Flo Performer intro- 140 mmHg and a systolic PG across the CTD of c ducer sheath kinked after the third stent and had to 18 mmHg. The CTD was dilated using a 10-mm by 3- be replaced. Ultimately, a total of four new stents cm Tyshak II balloond (RBP 3.5 ATM) followed by a were placed in the main pulmonary artery and RVOT 17-mm by 3-cm Tyshak II balloond (RBP 2.5 ATM). to achieve adequate relief of the RVOT obstruction Balloon valvuloplasty of the PS was performed using a 10-mm by 3-cm Tyshak II balloond (RBP 3.5 ATM). The echocardiogram 24 h after the proce- m Bard Peripheral Vascular Inc, Tempe, AZ 85281, USA. dure showed a systolic PG across the pulmonary 46 I. Sosa et al. valve and CTD of 29 mmHg and 1.5 mmHg, had a stent fracture 1 month after the procedure. respectively. Shortly after discharging the patient, Compared with the other cases in this case series, the ascites resolved. However, the patient pre- the stent was placed considerably more proximally sented 5 months later with dyspnea due to pleural into the right ventricle, and there was more severe effusion, requiring periodic drainage. An echo- dynamic RVOT obstruction as noted from angiog- cardiogram showed no change in the PG across the raphy, suggesting that compression by the RVOT CTD but a PG across the pulmonary valve of may have contributed to cyclic fatigue on the stent 120 mmHg. There was concern that the pleural material, ultimately leading to its fracture. The effusion was secondary to the PS, and a Cordis concept of cyclic fatigue states that any metallic Palmaz Genesis 28-mm by 10-mm stente was stent will fatigue and eventually fracture placed as described in case 1 (Video 5). Angiog- depending on time, loading conditions, or defor- raphy confirmed relief of the obstruction (Video mation [5] and needs to be considered when 6). An echocardiogram 24 h after the procedure choosing a stent. Despite using stents with the showed a systolic PG across the stent of 26 mmHg highest radial strength available, the combination and pulmonic regurgitation (PHT of 178 ms). Fur- of metal cyclic fatigue and the strength of the ther echocardiograms at 1, 3, and 6 months hypertrophied cardiac muscle make it difficult to showed correct stent placement across the avoid stent fracture and migration. We suggest stenosis with unchanged pressures across the stent that careful planning should be performed to avoid or CTD. However, the pleural effusion did not placing the stent too proximally within the RVOT to resolve, requiring frequent drainage. After peri- minimize this complication while making sure that odic thoracocentesis and antibiotic therapy, a there is adequate length proximal to the obstruc- computed tomography angiogram confirmed the tion to anchor the stent in position. Maximizing the presence of a torsion of the left cranial lung lobe. dose of beta blockers to reduce infundibular A lung lobectomy was performed, and patient hypertrophy and dynamic obstruction may also recovered uneventfully. Pleural effusion resolved help reduce the risk of stent fracture at the level and did not recur. Patient is asymptomatic at the of the RVOT. Using a BIB balloon may allow opti- time of writing 29 months after the procedure. mization of the stent position as the partially inflated stent can typically be repositioned more proximally or distally before full deployment. The Discussion BIB catheters have an inner balloon that is half the diameter and 1 cm shorter than the outer balloon Despite the popularity of BV to treat valvular PS with a burst pressure of 4.5e5.0 ATM. Other [2], there are a number of cases where an ade- techniques such as rapid pacing [6] or inducing quate reduction on the PG is not achieved. Loca- bradycardia [7] can also be used to minimize car- telli et al. [3] found an optimal outcome with a PG diac motion and help with successful deployment. of less than 50 mmHg in 56% of all dogs treated The coronary artery anatomy was assessed with BV in the long term, and this was poorer in the during the initial echocardiogram. If the dog was a type B dogs (38%). Severely dysplastic valves, with breed believed to be at risk of an R2A anomaly and or without hypoplasia of the pulmonary artery the left coronary artery could not be clearly annulus, are important factors that may make visualized, the coronary artery anatomy was routine valvuloplasty unsuccessful. This case assessed by angiography at the time of the cath- report shows the long-term outcome of cases with eterization. Again, if the anatomy could not be PS that underwent stent angioplasty with an identified during the levo phase of a right ven- immediate reduction in PG (see Table 1). Three of tricular injection, selective aortic angiography was the four dogs had a previously unsuccessful BV. In performed. Standard doses reported of atenolol the case where a stent was chosen initially, the range from 0.25 to 1 mg/kg q 12e24 h [8], but valve leaflets appeared very thick and dysplastic; achieving a reduction of the heart rate may it was felt unlikely that the dog would benefit from require higher doses. The reason for this disparity BV. A previous case report [4] described the suc- in therapeutic effects is unknown, but poly- cessful deployment of stents in two cases of PS, morphisms on adrenergic receptors play an with resolution of clinical signs. Restenosis led to important role in people [9]. Polymorphisms in the euthanasia of both dogs 7 and 8 months after canine and feline beta-1 receptors have been procedure. Stents were successfully deployed in identified [10,11], and this should be considered all our dogs, and long-term follow-up (3 to when evaluating the efficacy of beta blockers. 5 years at the time of writing this article) showed Preoperatively, the authors used a dose of beta good results except in one dog. Case 3 of our study blockers based on the effect on the heart rate Stent angioplasty for pulmonic stenosis. 47 rather than on body weight, reaching doses of up the patients that are alive at the time of writing to 2.5 mg/kg every 12 h to obtain a heart rate this article demonstrate clinical consequences around 70 beats per minute, with minimal increase from this complication. It may be that the shorter in the rate during excitement. This was achieved in lifespan of canine patients compared with humans three of the four cases and slow up-titration hel- makes this less of a consideration. Right ven- ped to minimize side effects. tricular outflow tract stenting in humans is more Placing vascular stents raises the concern for commonly a bridge to a definitive repair using intravascular thrombosis. Whether anticoagulant cardiopulmonary bypass [16]. Perhaps, patients and/or antiplatelet therapy is necessary in these with concurrent severe tricuspid regurgitation may cases is not known. In people, stent thrombosis after have a different outcome. None of the patients in bare-metal stent typically occurs within the first 30 this report had tricuspid regurgitation. days after implantation [12]. The addition of dual- Owing to the severe regurgitation and volume antiplatelet therapy for up to 6 to 12 months after overload after stent implantation, it is difficult to coronary stent implantation has resolved this assess the systolic PG accurately. The increase in flow problem [13]. We followed the same approach, and velocity across the stent typically indicates either a no signs of thrombus formation were seen in our smaller orifice (obstruction) or increased flow due to cases. Aspirin and clopidogrel were discontinued regurgitation [17]. The shortened PHT of the pul- after a period of 6 months without obvious wor- monic regurgitation observed in all patients suggests sening of the echocardiographic findings. that the increase in flow velocity may be due to After the first stent fractured in case 2, its severe regurgitation, rather than true reobstruction/ migration did not impair the pulmonary blood flow. narrowing of the pulmonary outflow tract and may This was likely due to the uncovered nature of the explain some of the increase in velocity with time. stent. Although the use of covered stents can help Although these dogs did not have any obvious minimize growth through the metallic skeleton of clinical signs at presentation, all owners reported an the stent, we recommend avoiding their use for the increase in activity after stent implantation, sug- treatment of PS to prevent acute obstruction to gesting that exercise intolerance and/or reduced blood flow should the stent migrate into the pul- activity was initially present. Case 4 developed monary arteries [14]. The large diameter covered pleural effusion and lung lobe torsion after the stents currently available in the United States are intervention for the CTD and routine valvuloplasty, made of platinum which provides less radial and the effusion resolved after lung lobectomy. strength than their stainless steel counterparts. Therefore, it is unlikely that the PS played an This may place them at higher risk for compression important role in the clinical picture of this case. or fracture after implantation. In addition, the This case report shows the long-term evolution platinumeiridium stent frame of the large diame- of patients with PS after stent implantation. ter covered stents currently available in the United Whether this procedure provides a longer survival States is similar to the platinumeiridium stent compared with routine BV remains unknown, and frame used to manufacture the Melody Trans- future controlled studies are necessary. However, catheter Pulmonary Valven which is known to this procedure may be a viable option for those commonly experience stent fracture after implan- patients that do not respond to balloon dilation or tation in dysfunctional RVOT conduits [15]. Actual those that are likely to have a poor outcome. stent selection depends on availability and the size of the RVOT. Stents can be overdilated so their ‘true’ maximal expandable diameter is greater Conflicts of Interest Statement than the range indicated by the manufacturer [16]. Long-term evaluation of the three other cases in No conflicts of interest are declared by any author. which the stent did not migrate showed mildly decreased right ventricular hypertrophy, with an increase of the right ventricular systolic and dia- stolic internal diameters, most likely secondary to Supplementary data the pulmonic regurgitation. Severe pulmonary regurgitation caused by a virtually absent pul- Supplementary data to this article can be monic valve is a sequela that needs to be consid- found online at https://doi.org/10.1016/j. ered after stent implantation. However, none of jvc.2018.10.007.

n Medtronic, Minneapolis, MN, 55432, USA. 48 I. Sosa et al.

Video table Video Title Description 1 Case 1: Transthoracic two-dimensional Compilation of echocardiographic images of case 1, before echocardiography before and after stent and after stent implantation procedure 2 Case 1: Right ventricular angiogram Right ventricular angiogram from case 1 showing the right ventricular outflow tract obstruction and dynamic compression 3 Case 2: Stent intervention Compilation of angiographic images of case 2 during and after stent implantation 4 Case 3: Second intervention with Compilation of angiographic images of case 3 during the multiple stents second intervention. 5 Case 4: Inner balloon inflation Angiogram during stent implantation in case 4 with the inner balloon inflated. The stent can be manipulated to ensure correct positioning 6 Case 4: Right ventricular angiogram Angiogram after final stent placement showing relief of the after stent placement obstruction

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