A solution to the problem of an unexpanded palmaz-schatz stent following balloon rupture

The Palmaz-Schatz stent is a balloon expandable stent. Although easy to deploy, problems can occur. One problem is balloon rupture resulting in a partially expanded stent, which can be difficult to expand fully. This report illustrates how a Probing catheter and balloon can solve this potentially serious problem.     

Successful retrieval of unexpanded Palmaz-Schatz stent from left main coronary artery

A 64-year-old patient with silent myocardial ischemia after anterior myocardial infarction was treated with directional coronary atherectomy, balloon angioplasty, and placement of Palmaz-Schatz stent. An unexpanded Palmaz-Schatz stent was retained in the left main coronary artery and was treated successfully with a nitinol goose-neck snare. After this procedure, another Palmaz-Schatz stent was successfully implanted without any complications. © 1996 Wiley-Liss, Inc.     

Deployment of a previously embolized,unexpanded, and disarticulated Palmaz-Schatz stent

Stent embolization is a rare but acknowledged complication of placement of disarticulated (half) Palmaz-Schatz stents. We report a case in which we diagnosed a previously unrecognized, embolized, undeployed half-stent in the distal LAD, causing slow flow, and then deployed the stent where it lay, resulting in improved flow. The literature on treatment of coronary stent embolization and on cutting and preparing half-stents for deployment is discussed. Cathet. Cardiovasc. Diagn. 42:331–334, 1997. © 1997 Wiley-Liss, Inc.     

Distortion of Palmaz-Schatz stent geometry following side-branch balloon dilation through the stent in a rabbit model

The compromise of side-branches following coronary angioplasty of the parent vessel remains a limitation of the procedure. Reports of dilation through a Palmaz-Schatz stent to salvage a compromised side-branch covered by the stent have been made. We examined the distortion of stent geometry which occurs following this procedure in a rabbit model. Palmaz-Schatz stents were placed at the aortoiliac bifurcation in 7 rabbits and the contralateral iliac artery was dilated through the stent. Despite good angiographic results, varied degrees of stent distortion were noted on gross pathologic analysis. Most distortion occurred when the arteries were dilated through the ends of the struts or through the “diamonds,” and least distortion occurred during dilation through the mid-articulation site. While good stent deployment is thought to be necessary for improved outcomes, the distortion of stents after balloon dilation through the stent, despite good angiographic results, may have negative implications for both short- and long-term outcomes. Cathet. Cardiovasc. Diagn. 40:422–426, 1997. © 1997 Wiley-Liss, Inc.     

Successful redeployment of an unexpanded coronary stent

We report on treatment of a patient in whom failure to deploy the distal portion of a Palmaz-Schatz stent occurred but was not recognized. After an unstable course, the patient underwent repeat coronary angiography, at which time the stent was rewired and redilated. Full deployment of the stent with restoration of TIMI grade 3 flow was achieved. The putative cause of the problem, incomplete deployment of the stent because of inadvertent advancement of the stent delivery sheath, should be avoided, and needs to be recognized if it occurs. Crossing and redilating the stent is possible, although technically difficult. Cathet. Cardiovasc. Diagn. 44:52–56, 1998. © 1998 Wiley-Liss, Inc.     

A method to eliminate articulation from the Palmaz-Schatz stent delivery system

It has been shown that the articulation site in the Palmaz-Schatz stent is a frequent site for restenosis. In this communication, we report on a new method to eliminate the articulation site in the Palmaz-Schatz stent to provide better lesion coverage and decrease the probability of plaque prolapse at the articulation site. We believe that this method is simple and effective, and that it serves an important clinical purpose. Cathet. Cardiovasc. Diagn. 40:212–216, 1997. © 1997 Wiley-Liss, Inc.     

Management of balloon rupture during rigid stent deployment

Balloon rupture may occur during stent placement and will only become apparent when the stent has been manouvered across the target stenosis and deployment is attempted. Withdrawal may be complicated by displacement of the stent off the balloon. We describe two cases in which a power injector was used to momentarily inflate the balloon and partially expand the stent in place. The punctured balloon could then be withdrawn and the stent fully deployed, using a new balloon. © 1995 Wiley-Liss, Inc.     

Successful limb salvage after recanalization of an occluded infrapopliteal artery utilizing a balloon expandable (Palmaz-Schatz) stent

This case describes the first reported successful management of an infrapopliteal artery intimal dissection utilizing the Palmaz-Schatz^TM balloon expandable stent. Stent deployment relieved the compromised blood flow caused by the intimal flap which could not be corrected by prolonged balloon inflation or removed with directional atherectomy, and averted any emergency surgical procedure. © 1993 Wiley-Liss, Inc.     

Use of bare-mounted Palmaz-Schatz stents employing the stent saddle technique on the delivery balloon: A single center experience

The major limitations of the Palmaz-Schatz stent stem from the design of its stent delivery system (SDS). The SDS is bulky and has poor trackability in lesions with proximal tortuosity and/or vessel calcification. The use of bare-mounted Palmaz-Schatz stents on low profile balloons represents an alternate approach for lesions that are not accessible for stenting with the SDS. Thus we evaluated the indications, procedural success rate, and in-hospital complications of patients undergoing bare stenting at a single center between 1 October 1995 through 30 September 1996. A total of 363 coronary interventions were performed during this period, including coronary stenting in 194 vessels. In 18 of these 194 vessels, bare-mounted Palmaz-Schatz stents were used. The indications for bare stenting were: inability to deliver the Palmaz-Schatz stent on SDS for suboptimal angioplasty results or acute/threatened abrupt closure; use of half stents; stenting in vessels < 3.0 mm; intermediate disease in the proximal segment that would have precluded optimal visualization of stent placement; and use of guides 7 French or smaller. Bare stenting was successful in 15 of the 18 patients (vessels) in whom it was attempted. There were no deaths, myocardial infarctions, stent thrombosis, repeat interventions, or significant bleeding in patients with successful bare stent delivery. The stents were successfully retrieved in the three patients in whom the stent could not be advanced into the target coronary segment. One of these patients had a propagated spiral dissection prior to attempts at bare stenting and required emergent bypass surgery. The remaining two patients with failed deployment had suboptimal angioplasty results but had an uncomplicated hospital course. Thus bare stenting represents an alternate percutaneous approach to tackle suboptimal procedural results and/or complications in patients who have failed stent deployment with the standard sheathed stent delivery system currently available in the United States. Cathet. Cardiovasc. Diagn. 41:361–368, 1997. Published 1997 Wiley-Liss Inc.

1 This article is a US government work and, as such, is in the public domain in the United States of America.

     

Limited balloon expansion through the struts of the Palmaz-Schatz and NIR stents compared with the Multi-Link stent

After placing a stent in the main vessel of a bifurcation lesion, it is sometimes necessary to perform further balloon inflation in order to treat an ostial lesion in a side branch. The stent struts may prevent full balloon expansion at the ostium of a side branch, resulting in residual ostial stenosis. The degree of completeness of balloon inflation may vary significantly depending on the stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the side branch were both 3.5 mm. Deployment of the Palmaz-Schatz stent (n=5), NIR stent (n=5) or Multi-Link stent (n=5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 12 atm. A 3.5-mm balloon catheter was then inflated to 12 atm through the stent struts of the main vessel and into the ostium of the side branch. The degree of completeness of balloon inflation (% balloon expansion) was calculated as (smallest diameter of balloon catheter/reference diameter of balloon catheter) x 100%. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch created with the stent struts were also measured. Limited balloon expansion through the struts was observed with the Palmaz-Schatz stent and the NIR stent, but almost full balloon expansion was observed with the Multi-Link stent (% balloon expansion: Palmaz-Schatz stent 80%, NIR stent 60%, Multi-Link stent 94%, p<0.01). The MLD and CSA of the dilated struts, representing the ostium of the side branch, of the Palmaz-Schatz stent (2.2+/-0.1 mm, 4.5+/-0.3 mm2) and the NIR stent (1.8+/-0.1 mm, 3.1+/-0.3 mm2) were significantly smaller compared with those of the Multi-Link stent (3.0+/-0.2 mm, 8.4+/-0.6 mm2) (p<0.01). The struts of the Palmaz-Schatz stent and the NIR stent deployed in the main vessel of a bifurcation prevent full expansion of a balloon catheter inflated at the side branch ostium. In contrast, almost full balloon expansion through the struts of the Multi-Link stent is achieved.     

Difference in security of stent jail between Palmaz-Schatz, NIR, and Multi-Link stents: the effect of balloon inflation through stent struts.

After placing a stent in the main vessel of a bifurcation lesion, it is often necessary to perform further balloon inflation or stent placement through the stent struts in order to treat a lesion of the secondary vessel or side branch. This balloon inflation with dilatation through the cells of the stent in the main vessel results in stent strut disfigurement. This disfigurement causes various degrees of stenosis within the main vessel secondary to stent strut deformity. The degree of strut deformity, and therefore stenosis, may vary significantly depending on stent design and structure. A model of a bifurcation lesion with an angle of 45 degrees was created from acrylic resin. The diameters of the main vessel and the secondary vessel were both 3.5 mm. Deployment of the Palmaz-Schatz stent (PS, n = 5), NIR stent (n = 5), or Multi-Link stent (n = 5) was performed in the main vessel with a 3.5-mm balloon catheter inflated to 6 atm. A second 3.5-mm balloon catheter was then inflated to 6 atm through the stent struts of the main vessel and into the ostium of the secondary vessel. The minimal lumen diameter (MLD) and cross-sectional area (CSA) at the ostium of the side branch and the stenosis within the main vessel were then measured, taking into account the stent deformity that occurred. Kissing balloon dilatation with two 3.5-mm balloon catheters was then performed and the stenosis secondary to stent deformity in the main vessel was remeasured. The MLD of the Multi-Link stent at the side-branch ostium was greater compared with those of the Palmaz-Schatz stent or the NIR stent (2.4 +/- 0.1, 1.6 +/- 0.1, 1.7 +/- 0.1 mm, P < 0.01) and CSA (4.9 +/- 0.5, 2.7 +/- 0.3, 2.5 +/- 0.3 mm(2), P < 0.01). Balloon inflation through the stent struts caused stent deformity that resulted in some degree of stenosis within the stent of the main vessel in all three stent types. Kissing balloon inflation reduced, but never eliminated, this stenosis. The percent stenosis in the main vessel secondary to stent deformity (PS 34% +/- 9%, NIR 25% +/- 8%, Multi-Link 34% +/- 7%, NS) and residual stenosis postkissing balloon inflation (PS 12% +/- 1%, NIR 10% +/- 3%, Multi-Link 14% +/- 3%, NS) were not significantly different among these three stents. At the side-branch ostium, the MLD and CSA were significantly greater for the Multi-Link stent compared with those of the Palmaz-Schatz or NIR stent. Balloon inflation through the stent struts caused stent deformity that resulted in stenosis within the stent in the main vessel. Kissing balloon inflation reduced this stenosis, but some residual stenosis always remained. The stenoses within the main vessel did not differ among the three stent types. Cathet. Cardiovasc. Intervent. 48:230-234, 1999.     

Coronary dissection due to overdilatation of an elastic membrane of the multi-link stent delivery system caused by balloon rupture

A 65-year-old male with unstable angina underwent coronary angiography, which revealed a significant stenotic lesion in the right coronary artery. This narrowing was subsequently treated with the Multi-Link stent. During the balloon inflation associated with stent deployment, balloon rupture occurred and resulted in overdilatation of an elastic membrane in the stent delivery system. This, in turn, resulted in coronary dissection, which required treatment with further stenting.     

A cellular solution to an information-processing problem

Signaling receptors on the cell surface are mobile and have evolved to efficiently sense and process mechanical or chemical information. We pose the problem of identifying the optimal strategy for placing a collection of distributed and mobile sensors to faithfully estimate a signal that varies in space and time. The optimal strategy has to balance two opposing objectives: the need to locally assemble sensors to reduce estimation noise and the need to spread them to reduce spatial error. This results in a phase transition in the space of strategies as a function of sensor density and efficiency. We show that these optimal strategies have been arrived at multiple times in diverse cell biology contexts, including the stationary lattice architecture of receptors on the bacterial cell surface and the active clustering of cell-surface signaling receptors in metazoan cells.The molecular characteristics of signaling receptors and their spatiotemporal organization have evolved to optimize different facets of information processing at the cell surface. A canonical information-processing problem involves designing strategies for a collection of distributed, noisy, mobile sensors to faithfully estimate a signal or function that varies in space and time (1). This problem appears naturally in many contexts, biological and nonbiological: (i) chemoattractant protein sensors on the bacteria cell surface (2, 3); (ii) galectin-glycoprotein assemblies designed for effective immune response on the surface of metazoan cells (4, 5); (iii) ligand-activated signaling protein receptors on the surface of eukaryotic cells (6–10); (iv) coclustering of integrin receptors to faithfully read and discriminate the rigidity and chemistry of a substrate (11); (v) clustering of e-cadherin receptors for effective adherence at cell–cell junctions (12); and even (vi) radio frequency (RF) sensor networks monitoring the environment or mobile targets (13). In the signal-processing community, this problem is known as data fusion or more generally information fusion (14, 15); however typical applications do not consider mobile sensors.In this paper we show how biology has, on multiple occasions, arrived at a solution to this optimization problem. The optimal solution needs to balance two opposing objectives, the need to locally assemble sensors to reduce estimation noise and the need to spread them out for broader spatial coverage. We show that in the space of strategies, this leads to a phase transition as a function of sensor density, sensor characteristics, and function properties. At very low sensor density, the optimal design corresponds to freely diffusing sensors. For sensor density above a threshold, there are two different optimal solutions as a function of a dimensionless parameter constructed from the sensor advection velocity and the correlation length and time of the incident signal. One optimal solution is that the sensors are static and located on a regular lattice grid. This is the strategy used in bacteria, such as Escherichia coli, to organize their chemoattractant receptors in a regular lattice array (3, 16), and in metazoan cells, where galectin-glycoproteins are organized in a lattice on the cell surface to effect an optimal immune response (4, 5). To realize this strategy, the cell needs to provide a rigid cortical scaffold that holds the receptors in place. Another optimal solution is to make the receptors mobile in such a way that a fraction of them form multiparticle nanoclusters, which then break up and reform randomly, the rest being uniformly distributed. Recent studies on the steady-state distribution of several cell-surface proteins reveal a stereotypical distribution of a fixed fraction of monomers and dynamic nanoclusters (6–9), and our information theoretic perspective could provide a general explanation for this. To realize this dynamic strategy, the cell surface needed to be relieved of the constraints imposed by the rigid scaffold and to be more regulatable. This strategy change needed the innovation of motor proteins and dynamic actin filaments, a regulated actomyosin machinery fueled by ATP, and a coupling of components of the cell surface to this cortical dynamic actin (17).     

Balloon rupture during peripheral stent implantation: A new technique for balloon retrieval

Balloon rupture is a known technical problem with implantation of vascular stents. In most cases, the ruptured balloon can be retrieved with simple maneuvers. In this case report, a peripheral balloon became trapped within an undeployed peripheral vascular stent and could not be removed by application of standard maneuvers. A novel approach to balloon retrieval was devised and undertaken with success. © 1993 Wiley-Liss, Inc.     

Intra-aortic balloon pump placement following aorto-iliac angioplasty and stent placement.

Approximately 20% of patients are unable to receive an intra-aortic balloon pump (IABP) due to aorto-iliac atherosclerotic disease. Aorto-iliac stenoses can be managed with angioplasty or stent placement; however, there are limited data about this strategy to facilitate IABP placement. Thirty-seven IABPs were placed in 35 patients. A total of 45 revascularization procedures were performed. With revascularization, the minimal lumen diameter increased from 2.78 +/- 1.46 to 6.75 +/- 2.36 mm (P < 0.0001). Limb ischemia occurred following 2/37 (5%) IABP insertions. Limb ischemia was managed with IABP removal and angioplasty. The mortality rate was 32%. Mortality was more common with chronic renal insufficiency (8/11, 73%; P = 0.0014), dialysis-dependent renal failure (3/3, 100%; P = 0.028), and presentation with acute myocardial infarction (8/15 patients, 53%; P = 0.036). Although no patients required vascular surgery for limb ischemia, one patient required surgery for bleeding. Angioplasty or stenting to facilitate IABP placement in patients with peripheral vascular disease is safe and effective.     

Fatal stent thrombosis following successful treatment of coronary artery rupture in an octogenarian

Primary intracoronary stenting of a calcified left anterior descending coronary artery stenosis was complicated by within-stent coronary artery rupture and subsequent cardiac tamponade. Despite pericardiocentesis and sealing of the perforation by additional stent placement, subsequent stent thrombosis resulted in anterior myocardial infarction and fatal cardiogenic shock. Cathet. Cardiovasc. Diagn. 42:434–436, 1997. © 1997 Wiley-Liss, Inc.     

Emergency covered stent implantation for rupture of the ascending aorta after balloon angioplasty

An acute rupture of the ascending aorta occurred in a 12‐year‐old boy after balloon angioplasty and was successfully treated by emergency covered stent implantation during resuscitation and preparation for support with extracorporeal membrane oxygenation. Neuroprotection with sedation, core temperature cooling and mild hyperventilation were undertaken. The boy recovered quickly. There were no neurological sequalae with a good interventional result at discharge and at follow‐up after 9 months. © 2010 Wiley‐Liss, Inc.     

Comparison of immediate and follow-up results of the short and long NIR stent with the Palmaz-Schatz stent.

The intrinsic characteristics of a stent including stent length may affect both procedural success and long-term outcome. The present study evaluated the immediate and follow-up results after implantation of the short and long NIR stent and compared these results with the Palmaz-Schatz stent. Between July 1995 and December 1996, stenting with a 16-mm NIR stent (NIR-16), a 32-mm NIR stent (NIR-32), or a Palmaz-Schatz stent (PS) was performed in 68, 57, and 155 lesions, respectively. There were no significant differences in the incidences of delivery failure (PS, 2.6%: NIR-16, 4.4%; NIR-32, 5.3%; p = NS) and procedural success (PS, 92%; NIR-16, 93%; NIR-32, 93%; p = NS) among the 3 groups. The reference vessel diameter was smaller in lesions with a 32-mm NIR stent than in those with a Palmaz-Schatz stent (PS, 3.14+/-0.58, NIR-16, 3.00+/-0.50; NIR-32, 2.90+/-0.47 mm; p <0.05). The lesion length was longer in lesions with a 32-mm NIR stent than in those with a Palmaz-Schatz or a 16-mm NIR stent (PS, 8.9+/-5.0; NIR-16, 11.0+/-4.1; NIR-32, 26.1+/-9.7 mm; p <0.01). After the procedure, the lesions with a 32-mm NIR stent had a smaller minimal lumen diameter than those with a Palmaz-Schatz stent (PS, 3.17+/-0.61; NIR-16, 2.99+/-0.51; NIR-32, 2.89+/-0.49 mm; p <0.01). At follow-up, a smaller minimal lumen diameter was observed in lesions with a 32-mm NIR stent than in those with a Palmaz-Schatz or a 16-mm NIR stent (PS, 2.32+/-0.98; NIR-16, 2.25+/-0.80; NIR-32, 1.68+/-0.79 mm; p <0.01). Restenosis rates were 16.5% in lesions with a Palmaz-Schatz stent, 13.3% in those with a 16-mm NIR stent, and 47.4% in those with a 32-mm NIR stent (p <0.01). Although stent delivery and procedural success of a long NIR stent were acceptable, the restenosis rate of a long NIR stent was high compared with a short NIR stent or a Palmaz-Schatz stent.