Coronary artery stents: Part I. Evolution of percutaneous coronary intervention

Preoperative echocardiogram does not increase time to surgery in hip fracture patients with prior percutaneous coronary intervention

BACKGROUND

The purpose of this study was to (1) assess the effect of preoperative echocardiogram on time to surgery and (2) assess the outcomes of patients with a previous percutaneous coronary intervention (PCI).

METHODS

Demographic, clinical, quality and cost data were obtained and a validated risk predictive tool (STTGMA) was calculated for each of a consecutive series of hip fracture patients. Comparative analyses of patients who had an echocardiogram prior to surgery or a PCI prior to hospitalization were performed.

RESULTS

Between 2014 and 2020, 2625 patients presented to our institution with a hip fracture. From this cohort 471 patients underwent a preoperative transthoracic echocardiogram (TTE), 30 who had a history of a PCI, and an additional 26 who had a history of PCI but did not undergo a preoperative TTE. Those undergoing a preoperative TTE had similar time (days) to surgery (1.73 vs 1.77, p = 0.86) and 30-day mortality (4% vs 7%, p = 0.545) regardless of PCI history. PCI patients who underwent a preoperative TTE experienced increased rates of 1-year mortality (27% vs 10%, p = 0.007) and major complications (23% vs 12%, p = 0.08) compared to those without a PCI history. PCI patients undergoing a preoperative TTE had a similar time (days) to surgery (1.77 vs 1.48, .p = 0.397) compared to PCI patients without a preoperative TTE. Patients who underwent a preoperative TTE had higher rates of 90-day readmission (31.0% vs 8.0%, p = 0.047) and 1-year mortality (26.7% vs 3.8%, p = 0.029).

CONCLUSIONS

Having a preoperative TTE does not affect surgical wait times in hip fracture patients regardless of PCI history, but it may not improve mortality outcomes or reduce postoperative complications in patients with a history of a PCI.

Ultrathin-strut biodegradable polymer versus durable polymer drug-eluting stents: a meta-analysis

Objectives

Determine whether an ultrathin biodegradable polymer sirolimus-eluting stent (‘Orsiro’—BP-SES) has clinical benefits over second-generation durable polymer drug-eluting stents (DP-DES).

Methods

We conducted a prospective systematic review and meta-analysis of randomised clinical trials comparing Orsiro BP-SES against DP-DES (PROSPERO Registration: CRD42019147136). The primary outcome was target lesion failure (TLF): composite of cardiac death, target vessel myocardial infarction (TVMI) and clinically indicated target lesion revascularisation (TLR)) evaluated at the longest available follow-up.

Results

Nine trials randomised 11 302 patients to either Orsiro BP-SES or DP-DES. At mean weighted follow-up of 2.8 years, the primary outcome (TLF) occurred in 501 of 6089 (8.2%) participants with BP-SES compared with 495 of 5213 (9.5%) participants with DP-DES. This equates to an absolute risk reduction of 1.3% in TLF in favour of Orsiro BP-SES (OR 0.82; 95% CI 0.69 to 0.98; p=0.03). This was driven by a reduction in TVMI (OR 0.80; 95% CI 0.65 to 0.98; p=0.03). There were no significant differences in other clinical endpoints: cardiac death, TLR and stent thrombosis.

Conclusion

The Orsiro BP-SES shows promising clinical outcomes in patients undergoing percutaneous coronary intervention compared with contemporary second-generation DES at a short to medium term follow-up. More research is warranted to evaluate performance over a longer follow-up period and in different clinical and lesion subsets.

Design and Biomechanical Analysis of a Novel Retrievable Peripheral Vascular Stent

Structurally retrievable drug-eluting stents may have valuable clinical applications because they do not leave any foreign materials inside the patient's body. This article presents a novel design of retrievable peripheral vascular stent and the results from biomechanical analysis of its performance. Using the finite element analysis method, principal parameters of the stent were studied. Moreover, to ensure the practicability of the retrieval process, simulation, and in vitro experiments were performed. The retrieval force reached the maximum value when the whole retrievable part had been retrieved. Furthermore, the force was gradually increased during the retrieval process and remained constant after the main part had been retrieved. When the stent was being compressed, the maximum strain of the stent occurred at the connection between the stent's retrieval part and the main body part, at a value of 4%. The index of nonuniformity of the stent was too small to be counted both at the end of the compression and self-expansion processes. With the increase of moment, the bending stiffness (EI) of the stent decreased gradually. After bending moment was applied, the large strain region was mainly located in the stent's main body part rather than the retrieval part. The results of preliminary stent retrieval experiments demonstrated that the stent could be retrieved successfully. This novel retrievable stent displays promising biomechanical performance. The preliminary experiments demonstrated that the stent could be retrieved smoothly from the blood vessels.

Management of antiplatelet therapy in patients with coronary stents undergoing noncardiac surgery: association with adverse events

BACKGROUND

Perioperative discontinuation of antiplatelet therapy (APT) in patients with coronary stents has been associated with major adverse cardiac events. Our aim was to analyse the perioperative management of APT in such patients and its relationship to the incidence of major adverse cardiac and cerebrovascular events (MACCE) and major bleeding events (MBE) in noncardiac surgery.

METHODS

We completed a prospective multicentre observational study of patients with coronary stents undergoing noncardiac surgery in 11 hospitals in Spain. The main objectives were to record perioperative events and prospectively analyse the management of APT, and to assess whether the different preoperative APT regimens were associated with MACCE and MBE.

RESULTS

Of 432 surgical procedures studied, 15% experienced a perioperative MACCE and 37% a MBE. Overall mortality was 3.0%. Presurgical APT was prescribed in 95% of procedures, and was preoperatively discontinued in 15%. Surgery was urgent or emergent in 22% of patients, 31% were ASA IV, and 38% had a Revised Cardiac Risk Index of IV. MACCE were related to recent myocardial infarction (P=0.038), chronic kidney disease (P<0.001), insulin-dependent diabetes (P=0.006) and no preoperative APT (P=0.018). MBE also increased MACCE risk (P<0.001). We found statin therapy (P=0.049) and obesity (P=0.016) to be protective factors for MACCE.

CONCLUSIONS

Patients with coronary stents undergoing noncardiac surgery suffer a high incidence of perioperative adverse events, even with perioperative APT. Major adverse cardiac and cerebrovascular events are mainly related to previous medical conditions and perioperative major bleeingn events. Our findings should be treated with caution when applied to an elective surgery population.

CLINICAL TRIAL REGISTRATION

NCT01171612.

Targeting AGGF1 (angiogenic factor with G patch and FHA domains 1) for Blocking Neointimal Formation After Vascular Injury

Background

Despite recent improvements in angioplasty and placement of drug‐eluting stents in treatment of atherosclerosis, restenosis and in‐stent thrombosis impede treatment efficacy and cause numerous deaths. Research efforts are needed to identify new molecular targets for blocking restenosis. We aim to establish angiogenic factor AGGF1 (angiogenic factor with G patch and FHA domains 1) as a novel target for blocking neointimal formation and restenosis after vascular injury.

Methods and Results

AGGF1 shows strong expression in carotid arteries; however, its expression is markedly decreased in arteries after vascular injury. AGGF1^+/− mice show increased neointimal formation accompanied with increased proliferation of vascular smooth muscle cells (VSMCs) in carotid arteries after vascular injury. Importantly, AGGF1 protein therapy blocks neointimal formation after vascular injury by inhibiting the proliferation and promoting phenotypic switching of VSMCs to the contractile phenotype in mice in vivo. In vitro, AGGF1 significantly inhibits VSMCs proliferation and decreases the cell numbers at the S phase. AGGF1 also blocks platelet‐derived growth factor‐BB–induced proliferation, migration of VSMCs, increases expression of cyclin D, and decreases expression of p21 and p27. AGGF1 inhibits phenotypic switching of VSMCs to the synthetic phenotype by countering the inhibitory effect of platelet‐derived growth factor‐BB on SRF expression and the formation of the myocardin/SRF/CArG‐box complex involved in activation of VSMCs markers. Finally, we show that AGGF1 inhibits platelet‐derived growth factor‐BB–induced phosphorylation of MEK1/2, ERK1/2, and Elk phosphorylation involved in the phenotypic switching of VSMCs, and that overexpression of Elk abolishes the effect of AGGF1.

Conclusions

AGGF1 protein therapy is effective in blocking neointimal formation after vascular injury by regulating a novel AGGF1‐MEK1/2‐ERK1/2‐Elk‐myocardin‐SRF/p27 signaling pathway.

Coating Techniques and Release Kinetics of Drug-Eluting Stents

Implantation of drug-eluting stents (DESs) via percutaneous coronary intervention is the most popular treatment option to restore blood flow to occluded vasculature. The many devices currently used in clinic and under examination in research laboratories are manufactured using a variety of coating techniques to create the incorporated drug release platforms. These coating techniques offer various benefits including ease of use, expense of equipment, and design variability. This review paper discusses recent novel DES designs utilizing individual or a combination of these coating techniques and their resulting drug release profiles.

Smooth muscle specific overexpression of p22phox potentiates carotid artery wall thickening in response to injury

We hypothesized that transgenic mice overexpressing the p22^phox subunit of the NADPH oxidase selectively in smooth muscle (Tg^p22smc) would exhibit an exacerbated response to transluminal carotid injury compared to wild-type mice. To examine the role of reactive oxygen species (ROS) as a mediator of vascular injury, the injury response was quantified by measuring wall thickness (WT) and cross-sectional wall area (CSWA) of the injured and noninjured arteries in both Tg^p22smc and wild-type animals at days 3, 7, and 14 after injury. Akt, p38 MAPK, and Src activation were evaluated at the same time points using Western blotting. WT and CSWA following injury were significantly greater in Tg^p22smc mice at both 7 and 14 days after injury while noninjured contralateral carotids were similar between groups. Apocynin treatment attenuated the injury response in both groups and rendered the response similar between Tg^p22smc mice and wild-type mice. Following injury, carotid arteries from Tg^p22smc mice demonstrated elevated activation of Akt at day 3, while p38 MAPK and Src activation was elevated at day 7 compared to wild-type mice. Both increased activation and temporal regulation of these signaling pathways may contribute to enhanced vascular growth in response to injury in this transgenic model of elevated vascular ROS.

Multiple roles of connexins in atherosclerosis- and restenosis-induced vascular remodelling

Endothelial dysfunction is the initial step in atherosclerotic plaque development in large- and medium-sized arteries. This progressive disease, which starts during childhood, is characterized by the accumulation of lipids, macrophages, neutrophils, T lymphocytes and smooth muscle cells in the intima of the vessels. Erosion and rupture of the atherosclerotic plaque may induce myocardial infarction and cerebrovascular accidents, which are responsible for a large percentage of sudden deaths. The most common treatment for atherosclerosis is angioplasty and stent implantation, but these surgical interventions favour a vascular reaction called restenosis and the associated de-endothelialization increases the risk of thrombosis. This review provides an overview of the role of connexins, a large family of transmembrane proteins, in vascular remodelling associated with atherosclerosis and restenosis. The connexins expressed in the vascular wall are Cx37, Cx40, Cx43 and Cx45; their expressions vary with vascular territory and species. Connexins form hemichannels or gap junction channels, allowing the exchange of ions and small metabolites between the cytosol and extracellular space or between neighbouring cells, respectively. Connexins have important roles in vascular physiology; they support radial and longitudinal cell-to-cell communication in the vascular wall, and significant changes in their expression patterns have been described during atherosclerosis and restenosis.

Overview of Technical and Cost Considerations in Complex Percutaneous Coronary Intervention

Complex percutaneous coronary intervention (PCI), encompassing an ever-expanding range of challenging lesion sets and patient populations, accounts for a significant proportion of PCI procedures being performed currently. Specific lesion types associated with lower rates of procedural success and higher rates of recurrence or major adverse cardiac events (MACE) include multivessel disease, unprotected left main coronary artery disease, fibrocalcific or undilatable lesions, chronic total occlusions, degenerated saphenous vein graft lesions, thrombotic lesions, and bifurcation disease. Validated tools and technical strategies currently exist to address most procedural scenarios encountered and should be familiar to the complex PCI operator. Anticipated clinical outcomes, projected resource utilization, and cost considerations should all factor into the decisions of when, how, and in whom to intervene.

The perioperative management of treatment with anticoagulants and platelet aggregation inhibitors

BACKGROUND

When giving anticoagulants and inhibitors of platelet aggregation either prophylactically or therapeutically, physicians face the challenge of protecting patients from thromboembolic events without inducing harmful bleeding. Especially in the perioperative period, the use of these drugs requires a carefully balanced evaluation of their risks and benefits. Moreover, the choice of drug is difficult, because many different substances have been approved for clinical use.

METHOD

We selectively searched for relevant publications that appeared from 2003 to February 2013, with particular consideration of the guidelines of the European Society of Cardiology, the Association of Scientific Medical Societies in Germany (AWMF), the American College of Cardiology, and the American Heart Association.

RESULTS

Vitamin K antagonists (VKA), low molecular weight heparins, and fondaparinux are the established anticoagulants. The past few years have seen the introduction of orally administered selective inhibitors of the clotting factors IIa (dabigatran) and Xa (rivaroxaban, apixaban). The timing of perioperative interruption of anticoagulation is based on pharmacokinetic considerations rather than on evidence from clinical trials. Recent studies have shown that substituting short-acting anticoagulants for VKA before a procedure increases the risk of bleeding without lowering the risk of periprocedural thromboembolic events. The therapeutic spectrum of acetylsalicylic acid and clopidogrel has been broadened by the newer platelet aggregation inhibitors prasugrel and ticagrelor. Patients with drug eluting stents should be treated with dual platelet inhibition for 12 months because of the risk of in-stent thrombosis.

CONCLUSION

Anticoagulants and platelet aggregation inhibitors are commonly used drugs, but the evidence for their perioperative management is limited. The risks of thrombosis and of hemorrhage must be balanced against each other in the individual case. Anticoagulation need not be stopped for minor procedures.

Knockout of CD8 delays reendothelialization and accelerates neointima formation in injured arteries of mouse via TNF-α inhibiting the endothelial cells migration

Objective

Delayed or impaired reendothelialization is a major cause of stent thrombosis in the interventional treatment of coronary heart disease. T cells are involved in neointima formation of injured arteries. However, the regulated mechanism of reendothelialization and the role of CD8 T cell in reendothelialization are unclear.

Methods and Results

Immunofluorescence staining showed that CD8 positive cells were increased in wire injured femoral artery of mice. On day 21 after injury, elastin staining showed that knockout of CD8 (CD8^−/−) significantly increased intimal thickness and a ratio of intima to media by 1.8 folds and 1.9 folds respectively in injured arteries. Evans blue staining showed that knockout of CD8 delayed the reendothelialization area on day 7 after injury (18.8±0.5% versus 42.1±5.6%, p<0.05). In vitro, a migration assay revealed that CD8^−/− T cells co-cultured with WT macrophages significantly inhibited the migration of the endothelial cells (ECs); compared to CD4⁺ T cells, and CD8⁺ T cells could promote the ECs migration. Furthermore, real-time PCR analysis showed that knockout of CD8 increased the level of tumor necrosis factor α (TNF-α) in injured arteries and cytometric bead cytokine array showed that TNF-α was elevated in cultured CD8^−/− T cells. Finally, a wound-healing assay showed that recombinant TNF-α significantly inhibited the migration of ECs.

Conclusion

Our study suggested that CD8⁺ T cells could promote the reendothelialization and inhibit the neointima formation after the artery wire injury, and this effect is at least partly dependent on decreasing TNF-α production promoting ECs migration.

What would surgeons like from materials scientists?

Surgery involves the repair, resection, replacement, or improvement of body parts and functions and in numerous ways, surgery should be considered human engineering. There are many areas in which surgical materials could be improved, but surgeons are generally unaware of materials available for use, while materials scientists do not know what surgeons require. This article will review some of the areas where surgeons and materials scientists have interacted in the past and will discuss some of the most pressing problems which remain to be solved. These include better implant materials for hernia repair, breast reconstruction, the treatment of diabetes, vascular stenting and reconstruction, and electrical pacing devices. The combination of tissue engineering and nanomaterials has great potential for application to nearly every aspect of surgery. Tissue engineering will allow cells or artificial organs to be grown for specific uses while nanotechnology will help to ensure maximal biocompatibility. Biosensors will be combined with improved electrodes and pacing devices to control impaired neurological functions.

Painless myocardial ischemia is associated with mortality in patients with chronic kidney disease

BACKGROUND

Painless myocardial ischemia (PMI) is associated with poor outcomes in the general population. We hypothesized that the presence of PMI is inversely related to the level of kidney function and is associated with impaired survival in chronic kidney disease (CKD).

METHODS

A total of 356 patients who underwent percutaneous coronary intervention were assessed for PMI, which was defined as the absence of chest pain in response to balloon dilation of the affected vessel. Cox proportional hazards analysis was used to calculate 10-year all-cause mortality.

RESULTS

There was an increase in PMI occurrence by strata of estimated glomerular filtration rate (eGFR), whereby PMI was present in only 20.6% of individuals with eGFR ≥ 90 ml/min/1.73 m(2), but was found in 50.0% of individuals with eGFR <30 ml/min/1.73 m(2) (p = 0.004 for trend). Classification of individuals as having either CKD or PMI showed significant differences in adjusted mortality between groups (p < 0.001 for trend), with individuals having both CKD and PMI demonstrating the highest 10-year mortality. Compared to individuals with neither CKD nor PMI, individuals with CKD and no PMI had a hazard ratio (HR) for mortality of 1.64 (95% CI: 1.03-2.63, p = 0.038), while individuals with both PMI and CKD had an HR of 2.08 (1.30-3.33, p = 0.002).

CONCLUSION

PMI is common in the CKD population, is inversely related to the level of eGFR, and confers a substantially increased risk in CKD. These findings may partially explain the high mortality traditionally attributed to cardiovascular disease in CKD patients.

The creation and impact of a dedicated section on quality and patient safety in a clinical academic department

Optimizing the effectiveness, efficiency, integration, and satisfaction associated with delivered health care is not only highly principled but also good business practice in an extremely competitive environment. Programs that foster quality improvement and patient safety efforts while also promoting a scholarly focus can generate the incentives and organizational recognition needed to make patient safety and quality improvement bona fide components of the academic mission. The authors describe the development, implementation, and results of a dedicated Section on Quality and Patient Safety (SQPS) within an academic anesthesiology department. Spearheaded by a physician champion and vigorously supported by the departmental chair, this SQPS engaged core leaders from the Department of Anesthesiology. This departmental quality and patient safety management team adopted quality improvement and performance improvement techniques that have been successfully used in other industries. The SQPS has gained support through data-driven results and reiterative promotion. Transparency and accountability have also been powerful motivators for achieving clinician buy-in and changing behavior. Since its inception in 2007, the SQPS has initiated or managed through to completion more than 25 quality and performance improvement projects, including an intraoperative corneal injury reduction program, a wrong-sided regional anesthesia procedure, a drug-eluting coronary stent protocol, and a practice-improvement initiative for resident physicians. The SQPS has not only robustly promoted a departmental culture of quality patient care and safety but also set the standard for other departments and stakeholders within the authors' health system.

[Antiplatelet therapy after coronary stenting and its importance in total joint arthroplasty]

Coronary stenting is an effective treatment for reopening atherosclerotic occlusions of coronary arteries. Depending on the manifestation of coronary artery disease (stable CAD or acute coronary syndrome) and on the type of implanted stent, dual antiplatelet therapy is recommended for a period of 4 weeks to 12 months. In this period total joint replacement is associated with high blood loss and high perioperative morbidity. Therefore antiplatelet therapy is often discontinued and replaced by higher dosages of heparin for prophylactic anticoagulation. However, with this treatment regimen protection of the stent is doubtful and there is a high risk of stent thrombosis with myocardial infarction. The surgery should be scheduled after the dual antiplatelet therapy is replaced by lifelong aspirin therapy. On the other hand, if surgery cannot be postponed perioperative bridging of dual antiplatelet therapy can be conducted to minimize bleeding complications with the best possible stent protection. Lifelong therapy with aspirin should not be discontinued in any case.

Intracranial stents for treatment of acute ischemic stroke: evolution and current status

BACKGROUND

Intravascular stents have been applied to treat a variety of pathophysiologic conditions. With advances in stent design and delivery, stenting has become a viable treatment option in neurovascular disease. Recently, intracranial arterial stenting has received increasing interest as a modality to rapidly and effectively recanalize affected vessels in the setting of acute ischemic stroke.

METHODS

To examine the potential of stenting procedures for stroke, we compiled and analyzed relevant experimental and clinical studies in the available databases.

RESULTS

Our resulting discussion covers the brief history of stents, from their initial inception in the 1960s, to the developments of interventional cardiology, and finally to the treatment of acute occlusions of the neurovasculature. We also detail technological advances that have improved stent delivery to intracranial arteries and review the several clinical studies that feature stenting for the treatment of acute ischemic stroke.

CONCLUSION

Numerous clinical studies have revealed that stents are a quick and efficacious endovascular tool for acute ischemic stroke treatment. It appears likely that issues regarding design, safety, and feasibility of stent-based devices will experience further improvement and refinement, and from fruitful criticism of existing technologies and techniques, along with lessons from past mistakes, will arise safer and more effective devices.

Acute coronary syndrome: new and evolving therapies

There are many new developments in both the invasive and noninvasive treatment of ACS. As technology, pharmaceuticals, and research continue to bring new therapies to the forefront, it is essential that clinicians stay current in their understanding of how this new knowledge will impact patients and alter clinical outcomes.

The Management of Antiplatelet Therapy in Patients With Coronary Stents Undergoing Noncardiac Surgery

Whereas the development of coronary stents has been a major breakthrough in the treatment of coronary artery disease, stent thrombosis, associated with myocardial infarction and death, has introduced a new challenge in the care of patients with coronary stents undergoing noncardiac surgery. This review presents the authors’ recommendations regarding the optimal management of such patients. Elective surgery should be postponed for at least 6 weeks and optimally 3 months for a bare-metal stent and at least 1 year for a drug-eluting stent. On the other hand, managing a patient undergoing non-elective surgery is more difficult and necessitates a case-by-case assessment of bleeding risk versus thrombotic risk based on patient comorbidities, type of stents present, details of the coronary intervention, and type of surgical procedure. Patients with a risk of bleeding that outweighs the risk of stent thrombosis should discontinue at least clopidogrel, whereas all other patients should continue dual antiplatelet therapy throughout the perioperative period.

Prevention of the renarrowing of coronary arteries using drug-eluting stents in the perioperative period: an update

The management of patients scheduled for surgery with a coronary stent, and receiving 1 or more antiplatelet drugs, has many controversies. The premature discontinuation of antiplatelet drugs substantially increases the risk of stent thrombosis (ST), myocardial infarction, and cardiac death, and surgery under an altered platelet function could also lead to an increased risk of bleeding in the perioperative period. Because of the conflict in the recommendations, this article reviews the current antiplatelet protocols after positioning a coronary stent, the evidence of increased risk of ST associated with the withdrawal of antiplatelet drugs and increased bleeding risk associated with its maintenance, the different perioperative antiplatelet protocols when patients are scheduled for surgery or need an urgent operation, and the therapeutic options if excessive bleeding occurs.

The management of patients on dual antiplatelet therapy undergoing orthopedic surgery

Cardiovascular disease is prevalent in patients undergoing orthopedic surgery. Many patients who have undergone previous percutaneous coronary intervention (PCI) with stenting are on dual antiplatelet therapy in order to minimize the risk of stent thrombosis. The optimal management of these patients in the perioperative setting remains unclear. We aim to provide information about the management of patients who have undergone a PCI with stents who are subsequently indicated for an orthopedic procedure. We will review the concerns from a cardiologist's and orthopedic surgeon's perspective in regards to the management of these patients in the perioperative setting. In addition, the current American Heart Association, American College of Cardiology, Society for Cardiovascular Angiography and Interventions, and American College of Surgeons guidelines are reviewed. The decision to discontinue dual antiplatelet therapy in a patient who has undergone a PCI with stent should be made only after careful review of the risks for thrombosis and bleeding. Best practice suggests that these risks should be jointly assessed by the orthopedic surgeon and cardiologist. Those patients with stents at high risk of thrombosis should have surgery delayed if possible. There is little data supporting a significantly increased bleeding risk associated with mortality in orthopedic patients when antiplatelet therapy is continued perioperatively.

Mechanical Evaluation of Polyvinyl Alcohol Cryogels for Covered Stents

Covered stents could reduce restenosis rates by preventing cellular migration with a physical barrier and may have reduced thrombotic complications if an appropriate material is selected. Previous Dacron™ or poly(tetrafluoroethylene) (PTFE) covered stents have had mixed clinical results in part because they are too thick and too thrombogenic at small diameters. Ideally, the covering should be as thin as a stent strut, mechanically able to expand as much as a stent, and durable enough to withstand deployment. As an alternative to PTFE, thin polyvinyl alcohol (PVA) cryogel membranes were tested for their ability to stretch with uniaxial tension tests and for puncture strength with a modified ASTM method. Additionally, PVA cryogel covered stents were made by coating expanded bare metal stents. These covered stents were then hand-crimped onto a balloon catheter and expanded. PVA cryogel membranes were made as thin as 100 μm—thinner than some stent struts—and stretched to approximately 3.0 times their original diameter (similar to a stent during deployment). PVA cryogel membranes resisted puncture well with an average push-through displacement of 4.77 mm—allowing for safe deployment in vessels of up to 9 mm in diameter. Push-through displacement did not depend on membrane thickness in the range tested—a trait that could reduce stent profile without increased risk of puncture. All the PVA cryogel covered stents tolerated the crimping and expansion process well and there was little to no visible membrane damage. In conclusion, based on the results of these mechanical tests, PVA cryogels are mechanically suitable for covered stent membranes. This work represents a first step toward the creation of a new class of covered stent, which could prevent complications from both restenosis and thrombosis.

[Current aspects of anesthetic management in urological patients]

Patients with coronary stents should take clopidogrel and acetylsalicylic acid for 4 weeks or 12 months after stenting. Stopping this medication early, e.g., for surgery, results in a 90-fold increase in the patient's risk for myocardial infarction from stent thrombosis. The mortality due to perioperative acute coronary syndrome clearly exceeds that due to perioperative bleeding complications. If oral medication resulting in platelet inhibition has to be paused "bridging" with short-acting, intravenous GPIIb/IIIa antagonists is possible. In recent years perioperative beta-blockade has been recommended for patients with high coronary vascular risk, and recently also for those with medium or low risk. Current studies, however, indicate that patients on beta-blockers have increased perioperative mortality because of bradycardia, hypotension, and anemia. Therefore, anemia and hypotension should be rigorously avoided.Anesthetic management may have an influence on the postoperative course of cancer. Combined epidural-general anesthesia provides a benefit by minimizing the use of systemic opioids and volatile anesthetics. Presumably, this and a decreased response to surgical stress increase the ability of the patient's immune system to deal with cancer dissemination and micrometastasis.

Progress in platelet medicine: focus on stent thrombosis and drug resistance

The outcome importance of coronary stent thrombosis has mandated the careful management of these devices and their associated platelet blockade during the perioperative period. Recent trials have highlighted the catastrophic outcomes after stent thrombosis. The maintenance of clinically effective platelet blockade not only is essential to prevent stent thrombosis but also to optimize outcome in the integrated management of acute coronary syndromes. Dual antiplatelet blockade with aspirin and clopidogrel must balance the risks of ischemia and bleeding in patients with acute coronary syndromes, especially in the subset who require urgent surgical coronary revascularization. Platelet resistance to thienopyridines such as clopidogrel and prasugrel may be a significant risk factor for adverse cardiovascular outcomes. This phenomenon is detectable by point-of-care assays although standardized definitions and standardized testing batteries have yet to be formulated. The determinants of platelet resistance to thienopyridine therapy include genetic polymorphisms (especially related to hepatic drug metabolism) and drug interactions (especially the proton pump inhibitors). Novel platelet blockers are currently in late clinical development and will likely induce more consistent platelet blockade because of pharmacokinetic advantages including the lack of hepatic metabolism for activation. These agents will likely supersede clopidogrel and prasugrel if randomized trials show superior efficacy and clinical safety.

[Perioperative management of patients with coronary stents in non-cardiac surgery]

In patients with coronary stents scheduled for surgery the question arises whether and how antiplatelet therapy should be continued. Risks of perioperative bleeding and of acute stent thrombosis have to be considered simultaneously. The bleeding risk depends primarily on the kind of surgery and on patient comorbidity. The risk of stent thrombosis is increased in these patients due to the thrombogenic surface of the stents. The main determinants are hereby the time duration after stent implantation, the kind of the stent [uncoated (bare-metal stent, BMS) or coated (drug-eluting stent, DES)], as well as angiographic and clinical patient factors. Therefore, perioperative antiplatelet therapy has to be individually adapted for each patient. Bridging with heparin is ineffective. Bridging with intravenous antiplatelet drugs during the perioperative interruption of oral antiplatelet therapy might be a potential procedure in high-risk patients. Whether bedside monitoring of antiplatelet therapy improves the perioperative management of these patients and reduces adverse outcome is object of current studies.

Cardiovascular problems in noncardiac surgery

PURPOSE OF REVIEW

Perioperative cardiac complications remain a major area of concern as our surgical population increases in volume, age and frequency of comorbidity. A variety of strategies can be used to optimize patients and potentially reduce the incidence of these serious complications.

RECENT FINDINGS

Recent literature suggests a trend towards less invasive testing for detection and quantification of coronary artery disease and greater interest in pharmacologic 'cardioprotection' using beta-blockers, statins and other agents targeting heart rate control and other mechanisms (e.g. reducing inflammatory responses). The recent Perioperative Ischemic Evaluation study has substantially altered this approach at least towards widespread application to lower/intermediate risk cohorts. Considerable attention has been focused on ensuring optimal standardized perioperative management of patients with a recent percutaneous coronary intervention, particularly those with an intracoronary stent. Widespread surveillance of postoperative troponin release and increasing recognition of the prognostic potential of elevated preoperative brain natriuretic peptides point towards changing strategies for long-term risk stratification.

SUMMARY

The complexity of a particular patient's physiologic responses to a wide variety of surgical procedures, which are undergoing constant technological refinement generally associated with lesser degrees of invasivity and stress make calculation of patients' perioperative risk very challenging. At the present time, adequate information is available for the clinician to screen patients with high-risk preoperative predictors, delay elective surgery for patients with recent intracoronary stents and continue chronic beta-blockade in appropriate patients. New large-scale database and subanalyses of major trials (e.g. Perioperative Ischemic Evaluation and Coronary Artery Revascularization Prophylaxis) should provide additional information to minimize perioperative cardiac risk.

Intercellular Communication in Atherosclerosis

Cell-to-cell communication is a process necessary for physiological tissue homeostasis and appears often altered during disease. Gap junction channels, formed by connexins, allow the direct intercellular communication between adjacent cells. After a brief review of the pathophysiology of atherosclerosis, we will discuss the role of connexins throughout the different stages of the disease.

[Management of a high risk of thrombosis patient with drug-eluting stents undergoing a complete gastrectomy]

We report the case of a 70-year-old patient, with two drug-eluting stents (DES), scheduled for a complete gastrectomy for a gastric cancer. This case underlines management problems regarding a patient with a high risk of DES thrombosis in case of AAP withdrawal and a high risk of bleeding in case of AAP maintenance. At this time, no evidence-based recommendation is available for clinicians to manage these patients. Our strategy was therefore based on platelet function monitoring test, which is however neither available in clinical practice nor validated to predict haemorrhagic risk. Several biologic tests are under study; they could be useful to guide perioperative management of antiplatelet therapy in the clinical setting of surgical patients with DES.