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The concept of resonances and modes for the description of particle plasmons has recently received great interest, both in the context of efficient simulations as well as for an intuitive interpretation in physical terms. While resonance modes have been successfully employed for geometries whose optical response is governed by a few modes only, the resonance mode description exhibits considerable difficulties for larger nanoparticles with their richer mode spectra. We analyze the problem using a boundary element method approach together with a Mie solution for spherical particles, and identify the fixed link between the electric and magnetic components of the resonance modes as the main source for this shortcoming. We suggest a novel modal approximation scheme that allows us in principle to overcome this problem.
RESUMEN
BACKGROUND: Transcatheter aortic valve implantation (TAVI) has become the standard therapy for high-risk and non-operable patients with severe aortic stenosis. However, the procedure involves several adverse effects, such as rhythm and conduction disturbances. Patients with postprocedural left bundle branch block may have an increased mortality risk, whereas patients with preprocedural right bundle branch block display a higher rate of postinterventional bradyarrhythmias. OBJECTIVE: The purpose of this study was to investigate the occurrence of high-degree atrioventricular block (AVB) in patients with preexisting bundle branch block (BBB) or BBB occurring during TAVI. METHODS: In this prospective single-center study, 50 consecutive patients undergoing TAVI with the Medtronic CoreValve Revalving System were included. Of these patients, 17 with preexisting BBB or BBB occurring during TAVI received a primary prophylactic permanent DDD pacemaker, programmed to the SafeR-mode and featuring dual-channel event counters as well as stored intracardiac electrograms. Pacemaker readouts and intracardiac electrograms were analyzed for the occurrence of high-degree AVB. RESULTS: Ten of 17 patients (58.8%) with preexisting BBB or BBB occurring during TAVI developed episodes of high-degree AVB that were immediately terminated due to switch into DDD backup pacing. In 5 of the cases (29.4%), the first documented episode of high-degree AVB occurred after hospital discharge. Mean follow-up period was 578.1 ± 294.9 days. CONCLUSION: Development of high-degree AVB is a common complication in patients with preexisting BBB or BBB occurring during TAVI. Accordingly, intensified monitoring might be reasonable, especially in patients treated with the self-expandable Medtronic CoreValve Revalving System.
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Estenosis de la Válvula Aórtica/cirugía , Bloqueo Atrioventricular/epidemiología , Bloqueo de Rama/epidemiología , Complicaciones Intraoperatorias/epidemiología , Reemplazo de la Válvula Aórtica Transcatéter/efectos adversos , Distribución por Edad , Anciano , Anciano de 80 o más Años , Animales , Estenosis de la Válvula Aórtica/diagnóstico por imagen , Estenosis de la Válvula Aórtica/mortalidad , Bloqueo Atrioventricular/diagnóstico , Bloqueo Atrioventricular/terapia , Bloqueo de Rama/diagnóstico , Bloqueo de Rama/terapia , Estudios de Cohortes , Electrocardiografía/métodos , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Complicaciones Intraoperatorias/diagnóstico , Masculino , Marcapaso Artificial , Cobertura de Afecciones Preexistentes , Estudios Prospectivos , Índice de Severidad de la Enfermedad , Distribución por Sexo , Estadísticas no Paramétricas , Análisis de Supervivencia , Reemplazo de la Válvula Aórtica Transcatéter/métodos , Resultado del Tratamiento , UltrasonografíaRESUMEN
Statins are recommended for prevention of progression of cardiovascular disease after percutaneous coronary intervention (PCI). Although high-dose highly efficient statins are recommended, especially in high-risk patients, clinical data are scarce and further investigation in "real-world" settings is needed. One thousand five hundred twenty-eight consecutive patients, who underwent PCI for acute coronary syndrome, were included in a prospective registry from January 2003 to January 2011. In post hoc analysis, cardiovascular risk factors, co-morbidities, and circulating lipid parameters at the time of intervention were evaluated. As a primary end point, all-cause mortality after a follow-up period of 3 months was investigated. Results were compared between patients receiving high-dose highly effective statins (atorvastatin 80 mg or rosuvastatin 20 mg) versus patients receiving low-dose statins or who were without lipid-lowering therapy at the time of discharge. Nine hundred twenty-six patients (60.6%) received high-dose atorvastatin or rosuvastatin and 602 patients (39.4%) received low-dose statin therapy or were not on statins at discharge. Eight patients (0.9%) receiving high-dose statin therapy and 21 patients (3.5%) taking low-dose statins or no statins at discharge died during the 3-month follow-up (hazard ratio 0.244, 95% confidence interval 0.108 to 0.551, p=0.001). After propensity score adjustment the results remained significant (adjusted hazard ratio for high-dose statins 0.405, 95% confidence interval 0.176 to 0.931, p=0.033). In conclusion, in this single-center series of 1,528 real-world patients undergoing PCI for acute coronary syndrome, a significant reduction in short-term all-cause mortality could be demonstrated in patients receiving high-dose highly efficient statins compared with patients receiving low-dose statins or no lipid-lowering therapy.
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Síndrome Coronario Agudo/cirugía , Dislipidemias/tratamiento farmacológico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/administración & dosificación , Intervención Coronaria Percutánea/métodos , Stents , Síndrome Coronario Agudo/complicaciones , Síndrome Coronario Agudo/mortalidad , Anciano , Austria/epidemiología , Causas de Muerte/tendencias , Relación Dosis-Respuesta a Droga , Dislipidemias/sangre , Dislipidemias/complicaciones , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Tasa de Supervivencia/tendencias , Factores de Tiempo , Resultado del TratamientoRESUMEN
BACKGROUND: The aim of our study was to evaluate the effect of drug-eluting stents (DES) compared with bare-metal stents (BMS) on all-cause mortality and target vessel revascularization (TVR) in a "real-world" clinical setting. METHODS AND RESULTS: One thousand four hundred and ninety consecutive patients, who underwent PCI, were included in a prospective registry from January 2003 until December 2006. Patients were divided retrospectively into two groups: those who received a DES and those who received a BMS. The primary combined endpoint all-cause mortality or TVR and the individual endpoints death and TVR were evaluated during a mean follow-up period of 24.56 ± 12.5 months (range 6-52 months). In total 1,033 patients (69.3%) received BMS, while 457 patients (30.7%) received DES. With respect to clinical characteristics, significant differences between groups were found for age, hyperlipidemia, diabetes mellitus, heart failure, previous cerebral insult and presence of acute coronary syndrome (ACS) during intervention. Propensity score analysis was performed in attempt to eliminate this selection bias. With respect to the combined endpoint all-cause death or TVR, 12.9% of patients with DES and 21.3% with BMS (p = 0.015) had an event during the follow-up. 12.3% of patients with BMS but only 5.7% with DES died during the follow-up (p = 0.025). Thirty-three patients (7.2%) of the DES group and 99 patients (9.6%) of the BMS group (p = 0.1) needed TVR. CONCLUSION: Our results obtained in a "real-world" clinical setting exhibit a clinical long-term benefit for DES compared with BMS and underline the safety and efficacy of DES over BMS.
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Stents Liberadores de Fármacos , Revascularización Miocárdica/mortalidad , Stents , Anciano , Enfermedad Coronaria/terapia , Stents Liberadores de Fármacos/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Revascularización Miocárdica/métodos , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Retratamiento/estadística & datos numéricos , Factores de Riesgo , Stents/efectos adversos , Resultado del TratamientoRESUMEN
A combination antithrombotic and antiplatelet therapy with clopidogrel, aspirin, glycoprotein IIb/IIIa receptor inhibitors and heparins is routinely used as adjunct therapy in patients undergoing percutaneous coronary intervention (PCI). As all substances inhibit platelet function, bleeding and thrombocytopenia may occur. We report on three patients who developed isolated profound thrombocytopenia (platelet count of < 20,000/mm(3)) within 24 h after initiation of combination antiplatelet and antithrombotic therapy during a 1 year observation period in 443 consecutive patients undergoing PCI and stent implantation. The data from our cardiology unit revealed an incidence of an isolated profound thrombocytopenia in 0.7% of all patients on combination antithrombotic therapy and in 1.5% of patients with GPIIb/IIIa-blockers. In all three cases with isolated profound thrombocytopenia GPIIb/IIIa-blockers were found to be the causative agents. Negative results of HIT-assays excluded heparin induced thrombocytopenia type II. Despite the extremely low platelet count no severe bleeding was observed and in all cases platelet counts normalized within 3-4 days without specific interventions except discontinuation of the responsible agent. These findings are discussed in conjunct with an overview of the recent literature.
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Angioplastia Coronaria con Balón/efectos adversos , Inhibidores de Agregación Plaquetaria/efectos adversos , Trombocitopenia/inducido químicamente , Humanos , Masculino , Persona de Mediana Edad , Recuento de PlaquetasRESUMEN
BACKGROUND: The purpose of this study was to determine whether implementation of recent guidelines improves in-hospital mortality from acute ST-elevation myocardial infarction (STEMI) in a metropolitan area. METHODS AND RESULTS: We organized a network that consisted of the Viennese Ambulance Systems, which is responsible for diagnosis and triage of patients with acute STEMI, and 5 high-volume interventional cardiology departments to expand the performance of primary percutaneous catheter intervention (PPCI) and to use the fastest available reperfusion strategy in STEMI of short duration (2 to 3 hours from onset of symptoms), either PPCI or thrombolytic therapy (TT; prehospital or in-hospital), respectively. Implementation of guidelines resulted in increased numbers of patients receiving 1 of the 2 reperfusion strategies (from 66% to 86.6%). Accordingly, the proportion of patients not receiving reperfusion therapy dropped from 34% to 13.4%, respectively. PPCI usage increased from 16% to almost 60%, whereas the use of TT decreased from 50.5% to 26.7% in the participating centers. As a consequence, in-hospital mortality decreased from 16% before establishment of the network to 9.5%, including patients not receiving reperfusion therapy. Whereas PPCI and TT demonstrated comparable in-hospital mortality rates when initiated within 2 to 3 hours from onset of symptoms, PPCI was more effective in acute STEMI of >3 but <12 hours' duration. CONCLUSIONS: Implementation of recent guidelines for the treatment of acute STEMI by the organization of a cooperating network within a large metropolitan area was associated with a significant improvement in clinical outcomes.
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Angioplastia Coronaria con Balón/normas , Infarto del Miocardio/terapia , Reperfusión Miocárdica/normas , Anciano , Austria/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/epidemiología , Infarto del Miocardio/cirugía , Garantía de la Calidad de Atención de Salud , Sistema de Registros , Estudios Retrospectivos , Choque Cardiogénico/epidemiología , Factores de TiempoRESUMEN
Unfractionated heparin (UFH) as well as low-molecular-weight heparins (LMWH), especially enoxaparin, are recommended by the current international guidelines for routine used in the conservative treatment of patients with acute coronary syndromes (ACS). UFH is still the recommended antithrombin as soon as percutaneous coronary interventions (PCI) are performed, although the results of different trials clearly have demonstrated the benefit of enoxaparin also in interventional cardiology. Bleeding complications along PCI procedures can be minimized by avoiding crossover from enoxaparin to UFH or vice versa and by reducing the dosage of indirect antithrombins, particularly of enoxaparin, in patients with chronic renal dysfunction and/or the elderly. Especially for those patient groups, bivalirudin offers already today an effective alternative. There is increasing expectation concerning the use of bivalirudin in patients undergoing PCI procedures but firm data exist at present only for low- and medium-risk patients with non ST-elevation ACS. Results of still ongoing trials (ACUITY, HORIZONS) will help to further confirm the role of bivalirudin in patients with high-risk acute coronary syndromes. For other direct antithrombins, e.g., fondaparinux (a pentasaccharide) or melagatran, comparably few data are available at present. Whether these agents will make their way into clinical use, future will tell.