An introduction to provisional stenting

Provisional or conditional stenting should be defined as the use of stents limited to those conditions and cases in which the operator, despite an aggressive balloon angioplasty technique with large balloons and high pressure, has been unable to obtain a result that ensures optimal chances of early and late patency. The paramount issue is how to discriminate the patients with optimal results after balloon angioplasty for whom additional stent implantation is unlikely to improve or may even worsen long-term outcome. The better results of elective stent implantation in the OPUS study suggest that visual assessment of the PTCA result is not sufficient to detect lesions with suboptimal lumen gain after PTCA. The addition of physiologic parameters (Doppler flow velocity measurements, fractional flow reserve) has improved the results of the provisional stent group, with the best outcome observed when complex lesions and multivessel treatment were included in these studies (FROST, DESTINI). Intravascular ultrasound, although more expensive and time-consuming, has the additional advantage to guide the dilatation strategy.     

Coronary pressure and FFR predict long-term outcome after PTCA

Although coronary stents have been the most important improvement in percutaneous coronary interventions in the last 10 years, it is well known to interventionalists that many patients after percutaneous transluminal coronary angioplasty (PTCA) have a favourable outcome without stenting. Coronary angiography, however, is not sensitive enough to identify those particular patients and it has been suggested that a combination of angiographic and functional criteria would be more suitable to distinguish patients with a low restenosis chance after plain balloon angioplasty. In the present study, the authors investigated the value of coronary pressure measurement for conditional stenting in 85 patients. It was demonstrated that in patients in whom a high fractional flow reserve (FFR) was present (> 0.90), the incidence of coronary events at two-year follow-up was almost three times lower than in those patients with an FFR below 0.90. Such high FFRs could be obtained in approximately 45% of all patients. In an additional group of patients, it was demonstrated by intravascular ultrasound (IVUS) studies that the mechanism of a high FFR after plain balloon angioplasty is most likely the result of a larger lumen compared with patients with a suboptimal FFR. This means that, in patients in whom both the angiographic and the functional result after PTCA is optimal, a restenosis rate is achieved similar to that achieved by stenting. Obviously, in such patients, additional stenting and a number of problems in the long-term possibly related to stenting can be avoided. Therefore, coronary angiography and coronary pressure measurement have a complementary value in the evaluation of PTCA results and such information can be easily obtained by using a pressure wire instead of a regular guidewire.     

Clinical and quantitative angiographic outcomes following elective implantation of the self-expanding Wallstent for longer coronary artery lesions--final results of the Wellstent native study

BACKGROUND: Implantation of short balloon-expandable stents provides superior clinical and angiographic outcome compared with balloon angioplasty in selected patients. The purpose of the Wellstent study was to evaluate the safety and efficacy of the self-expanding Wallstent combined with aspirin and ticlopidine in patients with stable or unstable angina related to a native coronary lesion up to 45 mm in length. METHODS: 105 patients (111 lesions) with stable (57%) or unstable (43%) angina were included in this prospective multicentre evaluation. Angiography before and after Wallstent implantation and at 6-month follow-up was analysed at the core lab using the CAAS 2 system. The primary end-point was incidence of major adverse cardiac events (MACE) at 30 days. Secondary end-points were angiographic outcome at 6 months and MACE at 6 months and 1 year. RESULTS: Acute procedural success (successful stent implantation with residual stenosis <20%) was achieved in 99%. Mean reference diameter was 3.18 +/- 0.66 mm, minimal luminal diameter was 1.00 +/- 0.50 mm pre- and 2.84 +/- 0.47 mm poststent (diameter stenosis 16 +/- 6%). The mean hospital stay was 2.2 days. At 30 days, 95% of patients were free of MACE. At 6 month and 1 year clinical follow-up, 75% and 71% of patients, respectively, remained free of MACE, the majority of which (19 of 30) were re-interventions at re-angiography. In 90% of eligible patients, MLD at follow-up was 1.65 +/- 0.75 mm (late loss 1.20 +/- 0.66 mm, loss index 0.66), diameter stenosis 42 +/- 15%, with a restenosis rate of 32%. Longer stents were associated with greater luminal loss (P = 0.001) and less-favourable clinical outcome. CONCLUSIONS: Wallstent implantation, combined with aspirin and ticlopidine, achieved excellent acute and 30 day clinical results in a heterogenous high-risk patient group. Clinical outcome at 6 months and 1 year remained good, and most adverse events were re-PTCA during follow-up angiography. The loss index of 0.66 and restenosis rate of 32%, related in part to the use of longer stents, emphasizes the continuing need for effective anti-proliferative therapy.     

Intravascular-ultrasound-guided percutaneous transluminal coronary angioplasty/provisional stent implantation strategy: impact on long-term clinical follow-up

Two hundred and eighty-four consecutive patients with 438 native coronary artery stenoses were enrolled prospectively in a study of intravascular ultrasound (IVUS)-guided percutaneous transluminal coronary angioplasty (PTCA) with provisional stenting: (1) aggressive lesion-site media-to-media balloon-sizing; (2) IVUS-assessment of residual lumen dimensions to identify optimal PTCA results (minimum lumen area = 65% of the average of the proximal and distal reference lumen areas or = 6.0 mm(2) and no major dissection); and (3) liberal stent crossover. Overall, 206 stenoses in 134 patients (47%) were treated with PTCA alone. Reasons for crossover were flow-limiting or lumen-compromising dissections in 28% of patients and suboptimal IVUS minimum lumen area in 72% of patients. At one year, 8% of stenoses in the PTCA group and 16% in the stent crossover group required revascularization. In approximately half of the patients treated using an IVUS-guided aggressive PTCA strategy, stent implantation could be avoided without sacrificing an increase in acute complications or worse clinical outcome.     

Clinical and angiographic results with the ACS MULTI-LINK DUET trade mark Coronary Stent System - the DUET Study

BACKGROUND: The DUET Study is a multicenter prospective efficacy and safety evaluation of the ACS MULTI-LINK DUET coronary stainless steel balloon-expandable stent. AIMS: The primary objective was to determine the one-month incidence of MACE (major adverse cardiac events). The secondary objectives were the acute success rate, the restenosis and reocclusion rates (assessed by quantitative coronary angiography (QCA)) at six months and the occurrence of MACE in hospital and at six months. METHODS: Two hundred and ten patients were enrolled between February and June 1998 in 18 European centers. Successful stent placement was achieved in 209 patients. All patients were treated with ticlopidine 500 mg/day for one month and with aspirin >/=100 mg/day. To allow the investigators to gain familiarity with the stent system, the first one to three patients per center formed a separate lead-in population leaving an intention-to-treat population of 157 patients. The majority of the intention-to-treat population were male (79%); 28% had unstable angina, 69% had stable angina, 44% had had a previous myocardial infarction, 15% had had a previous percutaneous transluminal coronary angioplasty, and 3% had a history of stroke. The target vessel was 38.5% left anterior descending artery, 20.5% left circumflex artery and 41.0% right coronary artery. RESULTS: All but one of the intention-to-treat patients were effectively stented (17 required multiple stents). Six-month angiographic follow-up was available in 90% of the intention-to-treat population. Minimal lumen diameter (MLD) postprocedure was 2.61 +/- 0.33 mm, with a residual diameter stenosis of 16%. Six-month follow-up data showed an MLD of 1.87 +/- 0.56 mm with a residual diameter stenosis of 36%. The binary restenosis rate (>/=50% residual stenosis) was 15.6%. Up to one month following the procedure 94.9% of the population was MACE-free, with two subacute occlusions. At six months all patients were alive, of whom 82.8% were MACE-free, and 73% were free of anginal complaints. CONCLUSION: The results observed in the current DUET registry are comparable to data of other balloon-expandable-stent trials, with a low incidence of clinical events at follow-up.     

No influence of hemochromatosis-related gene mutations on restenosis rate in a retrospective study of 137 patients after coronary stent implantation

BACKGROUND: Recent publications have shown an increased risk of coronary artery disease and myocardial infarction in patients with alteration of the hemochromatosis-related gene (HFE gene). The HFE gene mutation is associated with elevated iron uptake and serum iron overloading. Iron plays an important role in promoting the oxidation of LDL cholesterol. The iron deposition in the endothelium and in the media is closely associated with the progression of atherosclerosis. However, it is unclear whether the mutation of the HFE gene also influences the rate of restenosis after coronary stent implantation. METHODS: In a retrospective analysis, 137 patients (pts.) who underwent elective coronary stent implantation were angiographically reevaluated after six months. All patients were part of the OPTICUS-study population which investigated optimized stent implantation guided by intravascular ultrasound. Computerized quantitative analysis was performed in all procedures in a double-blinded fashion. At six-month follow-up, DNA fragments containing the substitution of tyrosine for cytosine at codon 282 were amplified by PCR. The results were analyzed by polyacrylamide gel electrophoresis. Statistical analysis was performed by multivariate linear regression. RESULTS: According to the HFE gene polymorphism we formed two subgroups: 129 pts. (94%) did not show changes in HFE gene (NH), 8 pts. (6%) were heterozygous for HFE Cys282Tyr (H). The groups did not differ in age, gender, extent of coronary artery disease, initial degree and length of stenosis and all patients underwent re-angiography. At six-month follow-up the average luminal narrowing in the stented vessel was 36.2 +/- 20.3% in the NH group compared with 27.8 +/- 20.0% in the H group which was statistically not significant (n. s.). The minimal luminal diameter was 1.9 +/- 0.71 mm in the NH group and 2.2 +/- 0.66 mm in the H group respectively (n. s.). 33 pts (26%) in the NH group versus 2 pts (25%) in the H group had >/= 50% diameter narrowing at follow-up (n. s.). The odds ratio of stent restenosis in H patients was 0.932. CONCLUSIONS: The authors did not find any association between restenosis rate and HFE gene alteration and therefore, we conclude that the polymorphism of the HFE gene is not a risk factor for restenosis after coronary stent implantation.     

The Proliferation REduction with Vascular ENergy Trial (PREVENT)

PREVENT was the first prospective, randomized placebo-controlled study of intracoronary beta radiotherapy with ³²P. A total of 105 patients with de novo or restenotic lesions, treated by stenting or balloon angioplasty, received 0 (control), 16, 20, or 24 Gy to a depth of 1 mm beyond the lumen surface. Rates of restenosis (50% diameter stenosis or more) were significantly lower in radiotherapy patients at the target site (8% compared with 39%, P = 0.012) and at the target site plus adjacent segments (22% compared with 50%, P = 0.018). Stenosis adjacent to the target site and late thrombotic events reduced the overall clinical benefit of radiotherapy.     

Intravascular brachytherapy to prevent restenosis: dosimetric considerations.

Acute myocardial infarction is often the result of occlusion of one or more coronary arteries. Occlusion and restenosis (re-closing of the vessel) are principal reasons that percutaneous transluminal coronary angioplasty (PTCA) may fail to provide long-term benefit. PTCA has been a popular treatment, which is less invasive than surgeries involving revascularization of the myocardium, promising a better quality of life for patients. Unfortunately, the rate of restenosis after balloon angioplasty is high (approximately 30-50% in the first year after treatment). Recent data suggest that intraluminal irradiation of coronary arteries in conjunction with balloon angioplasty and/or stent implantation reduces the proliferation of smooth muscle cells and neointima formation, thereby inhibiting restenosis. In order to study radiation dosimetry in the patient and for this therapy, dose distributions for electrons and photons, with discrete energies, were simulated for blood vessels of diameter 1.5, 3 and 4.5 mm irradiated with balloon and wire sources. Electron and photon transport was performed in a simple model representing the system used for irradiation using the MCNP 4B code (Monte Carlo N-Particles). Specific calculations for balloon and wire sources were also carried out for a few radionuclides. In this work, strengths and drawbacks conceming the use of each radionuclide simulated, as well as source geometries are discussed. The dosimetry performed in this study will improve understanding of the benefit-to-risk ratio in intracoronary brachytherapy.     

The role of acute wall recoil and late restenosis: results of the OCBAS trial (Optimal Coronary Balloon Angioplasty with Provisional Stenting versus Primary Stent)

Early deterioration of minimal luminal diameter immediately after PTCA, has been associated with an increase of late restenosis. Lesions with no early loss after PTCA have a low restenosis rate. Coronary stents reduce restenosis in lesions exhibiting early wall recoil. The purpose of the OCBAS study was to compare two strategies during coronary interventions; provision vs. elective stenting. 116 patients with good PTCA results were randomized to stent (n = 57) or to optimal PTCA (n = 59). After randomization in PTCA group, 13.5% of the patients crossed over to stent due to early loss (provisional stenting). Baseline demographic and angiographic characteristics were similar in both groups of patients. At 7.6 months, 96.6% of the entire population had a follow-up angiographic study; 98.2% in the stent and 94.9% in the PTCA group. Immediate and follow-up angiographic data showed that acute gain was significantly higher in the stent than in the PTCA group (1.95 vs. 1.5 mm; P < 0.03). However, late loss was significantly higher in the stent than the PTCA groups (0.63 +/- 0.59 vs. 0.26 +/- 0.44, respectively; P = 0.01). Hence, net gain with both techniques was similar (1.32 +/- 0.3 vs. 1.24 +/- 0.29 mm for the stent and PTCA groups respectively; P = NS). Angiographic restenosis rate at follow-up (19.2% in stent vs. 16.4% in PTCA; P = NS) and TVR (17.5 in stent vs. 13.5% in PTCA; P = NS) were also similar. Furthermore, event-free survival was 80.8% in the stent versus 83.1% in the PTCA group (P = NS). Overall costs (hospital and follow-up) were US$591,740 in the stent versus US$398,480 in the PTCA group (P < 0.02). The strategy of the PTCA with delay angiogram and provisional stent if early loss occurs, had similar restenosis rate and TVR than universal use of bare stents.     

Clinical trends in stent treatment of simple and complex coronary disease

This is a retrospective analysis of a consecutive group of patients from a single medical center who underwent stent implantation. It describes 316 patients who constituted 53% of the angioplasty procedures carried out in a single year. The authors describe the complications and their 1-year follow-up. We aimed to study the short and long-term results of stenting in our centre in relation to multiple clinical and angiographic variables. During 1996, 316 consecutive patients were treated with stent implantation for a total of 381 coronary lesions. The pharmacological protocol methods of stent implantation and patient characteristics were used. Clinical variables were: age 59.1 3 10.7 years, diabetes mellitus 25.3%, hypertension 33.0% and angina pectoris 88.7% (unstable in 44.1%). Previous coronary surgery had been undergone by 9.2%. Multivessel disease was present in 56% of the patients. The indications for stenting were: primary 58.5%, suboptimal results 33.0% and threatened or acute occlusion 8.5%. Angiographic success was 98.9% and clinical success 96.8%. The major in-hospital complications were acute myocardial infarction (2.2%), acute revascularization (0.3%) and major bleeding (0.6%). All occurred within 24 h of revascularization. Repeated angiography was performed in 115 cases (30.2%) at 160.3 3 109.4 days after stent procedure for unstable angina (38.7%), stable angina (26.1%) and other causes (35.2%). The restenosis rate in those catheterized was 38.1%, with an overall clinical restenosis rate of 11.3% during the follow-up period. Restenosis was more prevalent among diabetic patients (17.9 vs 9.15%, P 3 0.02) and patients with prior balloon angioplasty (18.6 vs 9.75%, P 3 0.046). Clinical follow-up was available in 90.8% of the patients for 291 3 112 days. The actuarial survival at the end of the follow-up period was 93.8%. Death/myocardial infarction was associated with unstable angina pectoris (P 3 0.006), hypertension (P 3 0.001), smoking (P 3 0.046) and threatened or acute occlusion (P < 0.001). In the first year of extensive stent use, stenting is associated with high technical and clinical success rates. Long-term results after stent implantation are associated with the occurrence of acute or threatened occlusion, and the in-hospital complications diabetes mellitus and hypertension.     

Early results of endovascular treatment of chronic coronary occlusion in patients with ischemic heart disease

The early results of endovascular treatment of chronic coronary occlusion were studied. Immediate success rates were 67%. The factors that promote successful endovascular treatment in patients with this condition were as follows: less than 2-month disease duration, well-developed intersystemic collaterals, no "bridge" collaterals. Successful recanalization for chronic coronary occlusion improves the quality of life and bicycle ergometer test finding in patients, which reduces their needs of nitrates and beta-blockers. Coronary occlusion stenting yields better immediate angiographic results than does balloon angioplasty: residual stenosis and the minimum diameter of stenosis after stenting were 13.61 +/- 6.3% and 2.69 +/- 0.4 mm, respectively; those after balloon angioplasty were 23.1 +/- 8.1% and 2.31 +/- 0.37 mm, respectively.     

Provisional stenting in small vessels

Based on the currently available data, the strategy of routine stent placement in unselected lesions located in small coronary arteries provides good immediate results but is still associated with a high incidence of in-stent restenosis. Randomized trials comparing elective stenting with balloon angioplasty have not provided the demonstration that routine stenting is the best strategy for percutaneous intervention in coronary arteries with a reference diameter smaller than 2.75-3.0 mm. This paper describes the rationale for provisional stenting in this clinical setting and reviews the role of quantitative coronary angiography, intracoronary ultrasound and intracoronary Doppler measurements in the identification of lesions that would benefit from adjunctive stent placement after balloon angioplasty and in guiding stent implantation.     

Repeat stent implementation for recanalization of the proximal right coronary artery: a case report

Background

A stent in a false lumen is a common cause of stent occlusion after coronary percutaneous coronary artery intervention therapy, particularly in the culprit lesion of acute myocardial infarction. Here, we present an unusual case of successful recanalization of the proximal right coronary artery with implementation of another stent to crush the previous stent in the false lumen.

Case presentation

A 40-year-old Chinese man underwent coronary stent implementation in the proximal right coronary artery due to acute inferior wall myocardial infarction at another hospital. Six months later, he underwent coronary angiography re-examination for recurrent symptomatic angina at our hospital. Coronary angiography and intravascular ultrasound confirmed that the previous stent was deployed in the false lumen of the right coronary artery. Then, intravascular ultrasound was used to guide the wire to re-enter the true lumen of the proximal right coronary artery, and another stent was deployed into the true lumen to crush the previous stent.

Conclusion

Intravascular ultrasound proved to be a pivotal tool in confirming false or true lumen, as well as determining favorable proximal site entry points to avoid rewiring the mesh of the previous stent.

     

Clinical and Angiographic Outcomes after Intracoronary Bare-Metal Stenting

Background

Data from a large patient population regarding very long-term outcomes after BMS implantation are inadequate. This study aimed to evaluate the very long-term (8–17 years) clinical and long-term (3–5 years) angiographic outcomes after intracoronary bare-metal stenting (BMS).

Methods and Results

From the Cardiovascular Atherosclerosis and Percutaneous TrAnsluminal INterventions (CAPTAIN) registry, a total of 2391 patients with 2966 lesions treated with 3190 BMSs between November 1995 and May 2004 were evaluated. In total, 1898 patients with 2364 lesions, and 699 patients with 861 lesions underwent 6-month and 3- to 5- year angiographic follow-up, respectively. During a mean follow-up period of 149±51 months, 18.6% of the patients died (including 10.8% due to cardiac death), 6.1% developed reinfarction, 16.2% had target lesion revascularization (including 81% of the patients within the first year), 14.5% underwent new lesion stenting (including 72% of the patients after 3 years), 2.4% underwent coronary bypass surgery, and 1.6% had definite stent thrombosis. The overall cardiovascular event-free survival rate was 58.5%. The 6-month angiographic study indicated a 20% restenosis rate. The minimal luminal diameter increased from 0.65±0.44 mm to 3.02±0.46 mm immediately after stenting, decreased to 2.06±0.77 mm at the 6-month follow-up, and increased to 2.27±0.68 mm at the 3- to 5-year follow-up.

Conclusions

This study provides clinical and angiographic results from a large population of patients who underwent BMS implantations after a long-term follow-up period (149±51 months). The progression of coronary atherosclerosis developed over time, and presented with new lesion required stent implantation. The follow-up angiographic findings reconfirmed the late and sustained improvement in luminal diameter between 6 months and 3–5 years.     

Safety and efficacy of treatment with platelet GPIIb/IIIa receptor blockade in unstable angina patients awaiting PTCA at a referring clinic

BACKGROUND: Although balloon angioplasty has assumed an important role in the management of refractory unstable angina (UA), that is, UA that does not respond to conventional therapy, it is limited by complications related to thrombosis and acute coronary occlusion. The complication rate is higher in patients with UA than in those whose condition is stable. Preprocedural use of abciximab, a monoclonal platelet glycoprotein IIb/IIIa receptor blocker, has been used effectively in patients with UA, but its acceptance may be limited by safety concerns and economic constraints. The current trial investigated a protocol for abciximab pretreatment in patients with UA awaiting transfer from referring hospitals to a site of intervention (the 'drip and ship' protocol). AIMS: This observational study was conducted to evaluate whether a prophylactic, preprocedural regimen of abciximab can be safely and effectively administered to UA patients in referring hospitals while awaiting coronary angioplasty at the interventional clinic. METHODS: From April 1996 to December 1998, 168 consecutive patients with refractory UA (Braunwald class II or III) received abciximab prospectively at the referring clinic before undergoing PTCA or stent implantation at the interventional clinic. The following cost-conscious protocol was used: a 0.25 mg/kg bolus of abciximab followed by 10 micro g/min intravenously for 16 hours, in addition to intravenous nitrates, heparin and aspirin therapy. Patients were then transferred to a facility with PTCA capability via high-speed ambulance transport. No specific alterations of routine-transfer protocol were needed. Platelet aggregation studies were conducted during abciximab infusion. All interventions were performed while abciximab was given. Procedural and clinical success and long-term outcomes also were assessed. RESULTS: The primary angiographic success rate (patients with post-PTCA diameter stenosis < 50%) was 98%, and the in-hospital clinical success rate (angiographic success without major complications) was 98%. No major bleeding complications occurred during the abciximab pretreatment period. Platelet aggregation findings in the study patients showed a stable inhibition of >80% at the time of angioplasty. At 30-day follow-up, all patients were alive and 91% were free of major adverse events. Outcomes of balloon angioplasty and stenting were equally favorable, indicating no device-specific effect. Event-free survival at six months was 89% with a target vessel revascularization rate of 10%. CONCLUSION: Abciximab was administered safely and effectively to angioplasty patients with refractory UA awaiting transfer from a noninterventional setting to the site of angioplasty. These results extend the current knowledge base that has been established in randomized trials performed in interventional centers. The study protocol potentially could make abciximab therapy more feasible economically, and therefore more widely available to patients who are most likely to benefit from prophylactic administration.     

Local heparin delivery for prevention of second in-stent restenosis. Acute and long-term results in 47 consecutive cases

BACKGROUND: Heparin has been shown to reduce intimal thickening after arterial wall injury by inhibiting vascular smooth muscle cell proliferation and migration. The authors studied the acute and long-term results after local delivery of heparin after balloon angioplasty for in-stent restenosis. METHODS AND RESULTS: Forty-seven in-stent restenosis cases, 32 of them longer than 1 cm, were enrolled. After angioplasty local heparin delivery was performed using the Dispatch coronary infusion catheter (Scimed Life Systems/Boston Scientific Corp, Natick, MA, USA); the infusion rate was 99.9 ml per hour and a target dosage of 4000 iu heparin per site was intended to be delivered. In nine cases (19.15%) heparin delivery had to be stopped because of ischemia. One patient died six days after intervention. After a follow-up interval of 6-12 months target vessel revascularization rate was 28.26%. CONCLUSIONS: For the protocol used ischemia occurred more often than previously reported. Considering the fact that most patients had diffuse in-stent restenosis, the target revascularization rate at follow-up was acceptable.     

A single center experience with the newly designed R Stent in small coronary vessels

BACKGROUND: Over the past 10 years stents have been used more frequently for the treatment of de novo coronary artery stenosis. Initally these devices were used primarily in coronary arteries with diameters ranging from 3.0 to 4.0 mm. Traditionally, coronary arteries less than 3.0 mm in diameter were treated with only balloon angioplasty, due to the unavailablity of flexible, low profile, small diameter stents. In the past three years, many stents have been designed to be implanted in small coronary arteries. OBJECTIVE: The objective of this study was to evaluate the safety and feasiblity of the R Stent in patients with coronary lesions located in coronary arteries with a reference diameter 2.5-3.0 mm. METHODS AND RESULTS: Between November 1998 and September 1999, 32 patients with stable (37%) and unstable (63%) angina treated with the R Stent were included in this study. The treated lesions were in the right coronary artery (RCA) (n = 13), left cirumflex coronary artery (LCX) (n = 10), and left anterior descending coronary artery (LAD) (n = 9). Of these lesions thirteen were anatomically complex. Stent deployment was successful in 97% with one crossing failure in a patient with a vessel tortuosity of greater than 75 degrees of the circumflex artery. No post-procedual major adverse cardiac and cerebrovascular event (MACCE) occurred within 30 days of stent implantation. After the procedure, patients were scheduled for a two-week telephone follow-up and a one-month clinical evaluation. At 30 days, only one patient (3%) experienced the recurrence of angina Canadian cardiovascular society classification ((CCS) Class 2). All other patients were event and angina free. CONCLUSION: This first clinical experience in patients with small vessel disease shows that the use of the R stent is safe and feasible with low rates of acute stent thrombosis.     

Sudden volume changes of the lumen of inverted thyroid follicles in suspension cultures. Use in estimation of rates of water flux through thyroid epithelium

Inverted thyroid follicles in suspension culture were observed using dark-field illumination and time-lapse video enhancement techniques. The lumens of many follicles undergo episodes of rapid shrinkage followed by relatively slow dilation. The extent of shrinkage ranged from 10 to 40% of the initial diameter. The decrease in lumen diameter is accompanied by loss of luminal fluid. The rate of efflux of fluid amounted to from 1 to 90 microns3/micron2 of luminal surface/min. This was followed after several minutes by a slow and generally linear increase in lumen diameter with time that could be accounted for by an influx of fluid of the order of 0.5 micron3/micron2/min. It is possible that this phenomenon is due to a continued influx of fluid into the lumen until a junction opens between cells allowing a sudden loss of luminal fluid. The junction reseals and fluid begins to accumulate in the lumen. The phenomenon may be a three-dimensional analogue of the behavior of domes.     

Intravascular ultrasound assessment of culotte stent deployment for the treatment of stenoses at major coronary bifurcations

BACKGROUND: The mechanism for the disappointing late outcome following stenting of bifurcation lesions is unclear. This prospective observational study aims to evaluate culotte stent deployment and dimensions with intravascular ultrasound (IVUS). PATIENTS AND METHODS: Patients with bifurcation stenoses were treated using two stents in a culotte configuration. After optimizing the angiographic appearance of both stents, IVUS was used to evaluate both limbs of the culotte. The main outcome measures were cross-sectional area (CSA) and minimal lumen diameter (MLD) assessed by IVUS. RESULTS: Within the culotte stent, the final mean CSA in the main limb was 6.1 mm(2) (97% of reference) and in the side-limb was 5.9 mm(2) (97% of reference). However, in each case, the minimum CSA and IVUS MLD of both limbs was at the bifurcation point. For all patients, the final mean CSA at the bifurcation point of the main limb was 4.3 mm(2) (70% of main stent) and of the side-limb was 4.4 mm(2) (75% of side stent). The IVUS MLD at the bifurcation point of the main limb was 2.1 mm (78% of main stent) and of the side-limb was 2.1 mm (84% of the side stent). Importantly, this significant residual stenosis was not detectable with quantitative coronary angiography. CONCLUSIONS: IVUS evaluation of culotte stents is feasible. The minimum IVUS CSA and MLD of both limbs of the culotte stent is at the bifurcation point. Despite an optimal angiographic appearance a significant residual stenosis was noted with IVUS at each bifurcation point.     

血管内超声在冠脉复杂病变介入诊疗中的临床价值

目的:研究血管内超声在冠脉复杂病变介入诊疗中的临床价值。方法:30例确诊为冠心病的患者,其中男性23例,女性7例,先采用冠脉造影(CAG),选择美国心脏病学会和美国心脏病协会(ACC/AHA)推荐的冠脉分型C型中弥漫性病变(>20mm)、近端血管过度扭曲病变,然后行IVUS检查,PCI术后再行IVUS检查,比较两者及PCI前后IVUS结果的差异。结果:CAG示支架贴壁良好,再行IVUS检查示支架贴壁不良率达78.4%,IVUS观察均达到支架置入理想标准。结论:IVUS在评价支架贴壁情况、选择高压球囊后扩张时,有着更明显的优势。