Overview of pleiotropic effects of platelet P2Y12 receptor inhibitors.

Dual antiplatelet therapy consisting of one of the P2Y12 receptor inhibitors in conjunction with aspirin is the mainstay of treatment for patients with acute coronary syndromes (ACS) and those undergoing percutaneous coronary interventions (PCI). In recent years, multiple extra-platelet features of P2Y12 receptor antagonists have been reported in numerous clinical trials. The aim of this review is to summarise reported pleiotropic effects of clopidogrel, prasugrel, ticagrelor and other P2Y12 receptor blockers. We included observations made both in human and in animal models, together with proposed mechanisms of action for described features. If confirmed in randomised studies and properly applied to everyday practice, the observed extra-platelet actions could enable us to improve efficacy of ACS and post-PCI treatment, as well as to confine mortality and occurrence rate of cardiovascular events.

Management of atrial fibrillation in the Emergency Department: current approach and future expectations.

Atrial fibrillation (AF) is the most common cardiac dysrhythmia and occurs in 3.3%-10% of emergency admissions. It is frequently quoted for people over the age of 75, but the cases of AF in young subjects without structural heart disease are also increasing, therefore, leading to the evaluation of "lonely atrial fibrillation" as a new challenge for the clinician. The first diagnosis and treatment often occur in the emergency room and the emergency physician has therefore to evaluate the initial step towards the therapeutic decisions. Although international standard guidelines are available, AF treatment in the Emergency Department (ED) is still heterogeneous in terms of the management strategy chosen. There are two main strategies for the management of AF: rate and rhythm control. Moreover, antithrombotic treatment is pivotal in AF to prevent cardioembolic stroke and it is considered a primary objective after an accurate assessment of antithrombotic treatment risks and benefits. The introduction of innovative echocardiographic approach, directly in ED, seems to improve the management and risk stratification of patients with AF. This review aims to provide an overview about the current approach and the future expectations in the management of AF in ED. This manuscript represents a synopsis of the lectures on AF management in the ED of the Third Italian GREAT Network Congress, that was hold in Rome, 15-19 October 2012. We decided to use only the most relevant references for each contribution as suggested by each participant at this review.

Neither cyclosporine nor tacrolimus deteriorate endothelial function in renal transplant recipients assessed with reactive hyperernia index.

BACKGROUND: Cardiovascular mortality in renal transplant recipients is nearer 10-fold higher than in general population. Immunosuppressive therapy is one possible cause, for these drugs can modify cardiovascular risk factors, which can induce endothelial dysfunction, the first step in the process of atherosclerosis. The aim of this study was to compare vasodilatatory function of endothelium in renal transplant recipients in relation to the immunosuppressive drug-cyclosporine or tacrolimus. MATERIALS AND METHODS: We examined 40 patients at 48.9 ± 36 months post-renal transplantation: 22 taking tacrolimus (group 1) and 18 taking cyclosporine (group 2). The renal transplant recipients were compared with a control group of 18 healthy people. Endothelial function was assessed by peripheral arterial tonometry (PAT) using the EndoPAT 2000 device to measure RHI (reactive hyperemia index) and AI% (augmentation index%). RESULTS: The overall median values of RHI were higher than the value accepted as a normal (1.67). The RHI median value in group 1 was 2.00 (quartile 1: 1.66; quartile 2: 2.72), not different from that in group 2 [1.90 (quartile 1: 1.56; quartile 2: 2.17)] or the controls [2.11 (quartile 1: 1.77; quartile 2: 2.50)]. Multivariate analysis revealed age to be the independent factor influencing RHI in all examined groups but treatment with calcium channel blockers appeared to be the only independent factor influencing RHI among renal transplant recipients. AI% values were not significantly different between the 2 groups of renal transplant recipients, but it was significantly higher among the controls than among subjects treated with tacrolimus. CONCLUSIONS: Vasodilatatory function of endothelium assessed by PAT in renal transplant recipients was not worse than in healthy people. It was not different between cyclosporine or tacrolimus. Arterial stiffness measured as AI% depend on age but not the calcineurin inhibitor, which showed little effect.

A critical overview on ticagrelor in acute coronary syndromes.

Until a few years ago, the mainstay of anti-platelet therapy in patients with acute coronary syndrome (ACS) was the combination of aspirin and clopidogrel, a P2Y12 receptor inhibitor. However, current clinical practice has now changed with the introduction of ticagrelor, a more potent cardiovascular drug than clopidogrel, without the limitations related to clopidogrel therapy. In this review, we provide a critical overview of ticagrelor in ACS, highlight the results with ticagrelor in several subgroups of patients and discuss the future trials.

Stress hyperglycaemia in patients with first myocardial infarction.

OBJECTIVE: To investigate the incidence of stress hyperglycaemia at first acute myocardial infarction (MI) with ST-segment elevation, occurrence of stress hyperglycaemia as a manifestation of previously undiagnosed abnormal glucose tolerance (AGT), and its relation to stress hormone levels. MATERIALS AND METHODS: The population of this prospective cohort study consisted of 243 patients. On admission glucose, adrenaline, noradrenaline and cortisol levels were measured. Patients without previously diagnosed diabetes (n = 204) underwent an oral glucose tolerance test on day 3 of hospitalisation and 3 months after discharge. RESULTS: Abnormal glucose tolerance at day 3 was observed in 92 (45.1%) patients without a previous diagnosis of diabetes mellitus and resolved after 3 months in 46 (50.0%) patients (p < 0.0001). Stress hyperglycaemia, defined as admission glycaemia ≥ 11.1 mmol/l, affected 34 (14.0%) study participants: 28 (54.9%) patients with diabetes vs. 3 (8.8%) subjects with newly detected impaired glucose intolerance (p < 0.00001) and 1 (2.2%) person with AGT at day 3 (p < 0.000001). Multivariable analysis identified elevated glycated haemoglobin (HbA(1c) ; p < 0.0000001), anterior MI (p < 0.05) and high admission cortisol concentration (p < 0.001), but not catecholamines, as independent predictors of stress hyperglycaemia. The receiver operating characteristic curve analysis revealed the optimal cut-off values of 8.2% for HbA(1c) and 47.7 µg/dl for admission cortisol with very good and sufficient diagnostic accuracies respectively. CONCLUSIONS: Newly detected AGT in patients with a first MI is transient in 50% of cases. Stress hyperglycaemia is a common finding in patients with a first MI with ST-segment elevation and diabetes mellitus, but is rarely observed in individuals with impaired glucose tolerance or transient AGT diagnosed during the acute phase of MI. The risk factors of stress hyperglycaemia occurrence include elevated HbA(1c) , anterior MI and high admission cortisol concentration.

Phenotyping vs. genotyping for prediction of clopidogrel efficacy and safety: the PEGASUS-PCI study.

BACKGROUND: Prognostic values of genotyping and phenotyping for assessment of clopidogrel responsiveness have been shown in independent studies. OBJECTIVES: To compare different assays for prediction of events during long-term follow-up. METHODS: In this prospective cohort study polymorphisms of CYP2C19*2 and CYP2C19*17 alleles, vasodilator-stimulated phosphoprotein phosphorylation (VASP) assay, multiple electrode aggregometry (MEA), cone and platelet analyser (CPA) and platelet function analyser (PFA-100) were performed in 416 patients undergoing percutaneous coronary intervention. The rates of events were recorded during a 12-month follow-up. RESULTS: Platelet aggregation by MEA predicted stent thrombosis (2.4%) better (c-index = 0.90; P < 0.001; sensitivity = 90%; specificity = 83%) than the VASP assay, CPA or PFA-100 (c-index < 0.70; P > 0.05; sensitivity < 70%; specificity < 70% for all) or even the CYP2C19*2 polymorphism (c-index < 0.56; P > 0.05; sensitivity = 30%; specificity = 71%). Survival analysis indicated that patients classified as poor responders by MEA had a substantially higher risk of developing stent thrombosis or MACE than clopidogrel responders (12.5% vs. 0.3%, P < 0.001, and 18.5% vs. 11.3%, P = 0.022, respectively), whereas poor metabolizers (CYP2C19*1/*2 or *2/*2 carriers) were not at increased risks (stent thrombosis, 2.7% vs. 2.5%, P > 0.05; MACE, 13.5% vs. 12.1%, P = 0.556). The incidence of major bleedings (2.6%) was numerically higher in patients with an enhanced vs. poor response to clopidogrel assessed by MEA (4% vs. 0%) or in ultra-metabolizers vs. regular metabolizers (CYP2C19*17/*17 vs. CYP2C19*1/*1; 9.5% vs. 2%). The classification tree analysis demonstrated that acute coronary syndrome at hospitalization and diabetes mellitus were the best discriminators for clopidogrel responder status. CONCLUSIONS: Phenotyping of platelet response to clopidogrel was a better predictor of stent thrombosis than genotyping.

Low-molecular-weight heparins vs. unfractionated heparin in the setting of percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis.

BACKGROUND: The aim of the current study was to perform two separate meta-analyses of available studies comparing low-molecular-weight heparins (LMWHs) vs. unfractionated heparin (UFH) in ST-elevation myocardial infarction (STEMI) patients treated (i) with primary percutaneous coronary intervention (pPCI) or (ii) with PCI after thrombolysis. METHODS: All-cause mortality was the pre-specified primary endpoint and major bleeding complications were recorded as the secondary endpoints. Relative risk (RR) with a 95% confidence interval (CI) and absolute risk reduction (ARR) were chosen as the effect measure. RESULTS: Ten studies comprising 16,286 patients were included. The median follow-up was 2 months for the primary endpoint. Among LMWHs, enoxaparin was the compound most frequently used. In the pPCI group, LMWHs were associated with a reduction in mortality [RR (95% CI) = 0.51 (0.41-0.64), P < 0.001, ARR = 3%] and major bleeding [RR (95% CI) = 0.68 (0.49-0.94), P = 0.02, ARR = 2.0%] as compared with UFH. Conversely, no clear evidence of benefits with LWMHs was observed in the PCI group after thrombolysis. Meta-regression showed that patients with a higher baseline risk had greater benefits from LMWHs (r = 0.72, P = 0.02). CONCLUSIONS: LMWHs were associated with greater efficacy and safety than UFH in STEMI patients treated with pPCI, with a significant relationship between risk profile and clinical benefits. Based on this meta-analysis, LMWHs may be considered as a preferred anticoagulant among STEMI patients undergoing pPCI.

Ischaemic and bleeding complications with new, compared to standard, ADP-antagonist regimens in acute coronary syndromes: a meta-analysis of randomized trials.

BACKGROUND: Platelets play a pivotal role in the pathogenesis of acute coronary syndromes (ACS) and their inhibition remains a mainstay therapy in this setting. We aimed to perform a meta-analysis of randomized trials to evaluate the benefits of new oral antiplatelet regimens to block platelet ADP-receptors compared to standard-dose clopidogrel (300 mg loading dose followed by 75 mg/daily). METHODS: We obtained results from all randomized trials enrolling patients with ACS. Primary endpoint was mortality. Secondary endpoints were myocardial infarction and definite in-stent thrombosis. Safety endpoint was the risk of major bleeding complications. We prespecified subanalyses according to new antiplatelet drugs (prasugrel/ticagrelor), high-dose clopidogrel (600 mg) and patients undergoing percutaneous coronary intervention. RESULTS: A total of seven randomized trials were finally included in the meta-analysis (n = 58 591). We observed a significant reduction in mortality (2.9% vs. 3.4%, OR = 0.87, 95% CI 0.79-0.95, P = 0.002), recurrent myocardial infarction (4.2% vs. 5.2%, OR = 0.80, 95% CI 0.74-0.87, P < 0.0001), definite in-stent thrombosis (0.9% vs. 1.7%, OR = 0.52, 95% CI 0.43-0.63, P < 0.0001). The benefits in mortality and reinfarction were driven by the treatment with prasugrel or ticagrelor, without a significant difference in terms of major bleeding complications as compared to standard-dose clopidogrel (5% vs. 4.7%, OR = 1.06 95% CI 0.96-1.17, P = 0.25). CONCLUSION: This meta-analysis showed that new oral antiplatelet regimens are associated with a significant reduction in mortality, reinfarction and in-stent thrombosis in ACS patients without an overall increase of major bleeding when treated with new antiplatelet drugs.

Early vs. delayed invasive strategy in patients with acute coronary syndromes without ST-segment elevation: a meta-analysis of randomized studies.

Although early percutaneous coronary intervention has been demonstrated to reduce the risk of mortality in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS), there are emerging conflicting data as to whether the catheterization needs to be done very early or whether it could be delayed while the patient receives medical therapy. The aim of the current study was to perform a meta-analysis of randomized controlled trials (RCTs) comparing early vs. delayed invasive strategies for NSTE-ACS patients. Medline/CENTRAL and the Web were searched for RCTs comparing early vs. delayed invasive strategies for NSTE-ACS patients. The primary endpoint was all cause mortality, whereas myocardial infarction (MI), coronary revascularizations and 30-day major bleeding complications were secondary end points. Fixed or random effects models were used based on statistical heterogeneity. As a sensitivity analysis, Bayesian random effects meta-analysis was performed in addition to the classical random effects meta-analysis. A total of 5 RCTs were finally included, enrolling 4155 patients. As compared with a delayed strategy, an early invasive approach did not significantly reduce the rates of death [odds ratio (OR) 95% confidence interval (95% CI) = 0.81 (95% CI 0.60-1.09), P = 0.17], MI [OR = 1.18 (95% CI 0.68-2.05), P = 0.55] or revascularizations [OR = 0.97 (0.77-1.24), P = 0.82]. There was a not significant trend toward fewer major bleeding complications for the early invasive approach [OR (95% CI) = 0.76 (0.55-1.04), P = 0.08]. The present meta-analysis shows that for NSTE-ACS patients a routine early invasive strategy does not significantly improve survival nor reduce MI and revascularization rates as compared with a delayed approach.

Percutaneous coronary intervention triggers a systemic inflammatory response in patients treated for in-stent restenosis -- comparison with stable and unstable angina.

OBJECTIVE AND DESIGN: It is believed that the magnitude of the systemic inflammatory response induced by percutaneous coronary intervention (PCI) impacts on the long-term outcomes in patients with stable angina (SA) and unstable angina (UA). We aimed to determine whether an inflammatory response appears in in-stent restenosis (ISR) patients undergoing balloon angioplasty and to assess its pattern and magnitude in relation to SA and UA subjects. SUBJECTS: 80 patients (59 with SA, 10 with UA, 11 with ISR) were enrolled into the prospective study. TREATMENT: SA and UA patients undergoing single vessel coronary balloon angioplasty followed by stenting versus ISR subjects in whom only balloon angioplasty was performed. METHODS: C-reactive protein (CRP), serum amyloid A (SAA), tumor necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) were measured in blood samples collected before and 6, 24 h and 1 month after the procedure. RESULTS: A comparable pattern of inflammatory response in terms of CRP and SAA concentrations in subjects undergoing PCI due to ISR and SA was discovered while in unstable patients its magnitude was substantially higher. CRP and SAA levels increased significantly in each group with the peak value at 24 h and the baseline levels remarkably correlated with the highest markers' concentrations. In contrast, preprocedural TNF-alpha concentrations were higher in ISR group when compared with SA and UA patients. Additionally, in ISR group a twofold increase in their values of borderline significance at 6 h was noted. SA and UA subjects were found to have significantly lower TNF-alpha levels at 6 and 24 h after the intervention though the marker concentrations markedly increased with peak values at 1 month. The levels of IL-10 did not differ at any time point between the groups. CONCLUSIONS: We suggest that PCI triggers a systemic inflammatory response in patients with ISR and considerable differences in its pattern when compared with SA and UA patients were demonstrated. Moreover, a high preprocedural TNF-alpha level and its increase provoked by PCI in the ISR group warrant the need for further investigation of its possible involvement in the restenosis process.

Echocardiographic morphometry of the right chambers of the heart in permanent cardiac pacing.

Permanent cardiac pacing is a method of choice in the treatment of specific arrhythmias and conduction disturbances. Clinical studies show that cardiac performance diminished at the site of impulse spreading. It determines local hypotrophy below the position of the pacing lead (early electric activation) with hypertrophic changes in the opposite lying myocardium (late electric activation). It seems that morphological changes, especially research by intravital methods, so relevant in permanent pacing to today's invasive cardiologist, are not understood in full. In connection with this we decided, on the basis on the echocardiographic examination, to evaluate in detail the morphology of the right ventricle and atrium in patients with permanent pacing. Research was carried out on a group of 124 patients (68 males, 56 females) from 40-93 years of age (avg. 68 +/- 14 yrs): 86 patients had implanted pacemakers or AICD (group I), the control group consisted of 38 patients with other cardiac diseases without any pacemaker devices (group II). We measured echocardiographically the following diameters: end-diastolic and systolic diameters of the right ventricle/atrium in short and long axis, diameter of the tricuspid orifice valve and calculated area of the tricuspid orifice based on a special formula. Regarding the morphometric parameters of the right ventricle and right atrium, we confirmed that all diameters of group I were overshooting in correlation to group II. Those differences, such as RVd-short and -long, RVs-long, RVinflow, RA-long and -short, TRId, were statistically significant. Regarding the area of the tricuspid orifice (TRIa), we did not observe any changes in the two examined groups. We concluded that patients with implanted devices have changes in the morphometric parameters of the right ventricle, atrium and orifice, but they do not depend on the duration of pacemaker implantation.

Adjunctive stent implantation following directional coronary atherectomy in patients with coronary artery disease.

OBJECTIVES: This prospective case-control study evaluated the acute and long-term results of stent implantation preceded by debulking of the plaque by means of directional coronary atherectomy. BACKGROUND: In comparison with balloon angioplasty, intracoronary stenting produces a larger luminal diameter, maintains artery patency and reduces the incidence of restenosis. Optimal stent deployment is a pivotal factor for achieving the best results, but the bulk of the atherosclerotic plaque opposes stent expansion and may limit the success of the procedure. Debulking of the plaque may provide a better milieu for optimal stent deployment. METHODS: Directional coronary atherectomy followed by a single Palmaz-Schatz stent implantation was attempted in 100 patients. The successes, complications and angiographic results of the combined procedure were evaluated both acutely and during follow-up. Matched patients undergoing successful Palmaz-Schatz stent implantation alone during the same period served as controls. RESULTS: Atherectomy followed by stent implantation was performed in 94 patients with 98 lesions; periprocedural complications were observed in four cases. The stenosis diameter decreased from 76+/-9% at baseline to 30+/-13% after atherectomy (p < 0.0001), and 5+/-9% after stent implantation (p < 0.0001); it increased to 27+/-15% at 6-month angiography (p < 0.0001). During the 14+/-10 months of follow-up, none of the patients died or experienced myocardial infarction, but three patients underwent target lesion revascularization. The patients undergoing stent implantation alone achieved smaller acute gains, tended to have a higher late lumen loss, had a higher restenosis rate (30.5% vs. 6.8%, p < 0.0001) and showed a greater incidence of clinical events during follow-up (p < 0.0001). CONCLUSIONS: Debulking atherosclerotic lesions by means of directional coronary atherectomy before stent implantation is a safe procedure with a high success rate and a low incidence of restenosis at follow-up.

[Evaluation of efficacy and mechanism of action of angioplasty and directed atherectomy assisted by intravascular ultrasonography]. / Ocena skutecznosci i mechanizmów dzialania angioplastyki oraz aterektomii kierunkowej za pomoca ultrasonografii wewnatrznaczyniowej.

Intravascular ultrasound (IVUS) is a unique method of coronary lumen visualization enabling also examination the structure of the artery wall. Aim of this study was to assess efficacy and mechanisms of action of balloon angioplasty (PTCA) and directional atherectomy by means of IVUS. IVUS examination was performed before and after mechanical revascularization procedure in 37 pts (DCA-19 pts, PTCA-18 pts). Both PTCA and DCA resulted in enlargement of the coronary artery lumen (2.29 +/- 1.19 mm2 vs 2.93 +/- 1.55 mm2) but, also external diameter of the vessel increased after the procedure (1.94 +/- 1.10 mm2 and 0.74 +/- 1.01 mm2 retrospectively). In 55.6% of cases after PTCA plaque rupture or artery wall dissection was observed, mainly in eccentric lesions (70%). IVUS allowed to recognize details of artery lumen and define efficiency of procedure. In about 15% cases decision to continue PTCA or DCA was made on the basis of IVUS images only. The mechanism in which PTCA modifies the artery lumen is diverse and depends on the structure of lesion. Factors possibly responsible for enlargement of the lumen are: stretching, squeezing and translocation of atheroma as well as cracking and dissections along the arterial wall. DCA effectiveness depends on the withdraw of the atheromatous deposit, however, in over one-half of cases also stretching has some effect.

Correlation between clinical and morphologic findings in unstable angina.

This study was undertaken to verify the hypothesis that the discrepant findings in published reports on the prevalence of thrombus in unstable angina depend on the inclusion of different clinical subsets in the various studies. We therefore correlated the clinical characteristics of patients included under the label of unstable angina with the morphologic features assessed by coronary angiography and intravascular ultrasound, and with histopathologic findings of atherectomy specimens. Fifty-eight patients with unstable angina (class B of the Braunwald classification) undergoing coronary arteriography followed by either coronary angioplasty (n = 20) or directional coronary atherectomy (n = 38) were studied. Fifteen patients were in class IB and 43 were in class II to IIIB. Among these 43 patients with angina at rest, 28 had ST-segment elevation during pain, and 15 had ST-segment depression, and 26 developed negative T waves on the baseline electrocardiogram (ECG) as a result of prolonged or repeated episodes of resting chest pain. Intravascular ultrasound examination of the culprit lesion was performed in 43 patients before the interventional procedure, and histopathologic analysis of atherectomy specimens was performed in 38 patients. Complex lesion morphology by angiography was observed in 31 patients (53%) without any significant relation to various clinical subsets. Patients in Braunwald class IB had more calcific plaques than patients in class II to IIIB (p < 0.001). Among patients with angina at rest, those with negative T waves on the baseline ECG, as well as those with transient ST elevation during pain, had a significantly higher incidence of noncalcific lesions (p = 0.001 for both). Analysis of atherectomy specimens revealed acute coronary lesions (thrombus and/or intraplaque hemorrhage) in 18 patients (47%). The incidence of acute coronary lesions was significantly higher in patients with than without negative T waves on the baseline ECG (p = 0.005), and increased further when negative T waves were combined with ST elevation during pain (p = 0.001). Multivariate analysis revealed that the presence orf negative T waves on the baseline ECG was the only explanatory variable related to the presence of acute coronary lesions by histology (p = 0.03). Patient subsets included in the broad spectrum of unstable angina have different morphologic features and incidence of acute coronary lesions by histology. These data provide an explanation for the discrepant findings in published reports on the relevance of thrombus formation in the pathogenesis of unstable angina.

Influence of plaque composition on luminal gain after balloon angioplasty, directional atherectomy, and coronary stenting.

This study was conducted to correlate the acute luminal enlargement achieved by three different nonsurgical revascularization procedures in 79 patients (32 treated by balloon angioplasty, 29 by directional atherectomy, and 18 by coronary stenting) with the morphologic characteristics of coronary plaques assessed by preprocedure intravascular ultrasound. The absolute luminal gain was 2.41 +/- 1.54 mm2 for balloon angioplasty, 3.17 +/- 1.8 mm2 for directional atherectomy, and 4.56 +/- 1.45 mm2 for coronary stenting (p = 0.00005). However, when luminal gain was corrected for the external vessel area (luminal gain index), such difference was no longer present (0.22 +/- 0.12 for balloon angioplasty, 0.24 +/- 0.15 for directional atherectomy, and 0.30 +/- 0.12 for coronary stenting, p = not significant). Concentric plaques treated by coronary stenting had a higher luminal gain index than eccentric plaques (p = 0.01). A comparison of the three devices showed that a similar luminal gain index was achieved in soft plaques, whereas coronary stenting was superior to directional atherectomy (0.41 +/- 0.10 vs 0.20 +/- 0.09, p = 0.002) and balloon angioplasty (0.41 +/- 0.10 vs 0.19 +/- 0.08, p = 0.0005) in concentric plaques. Coronary stenting also induced a greater luminal gain index than directional atherectomy in calcific plaques (0.30 +/- 0.11 vs 0.18 +/- 0.09, p = 0.04). In conclusion, these data show that plaque morphology assessed by preprocedure intracoronary ultrasound influences the acute luminal enlargement achieved by different coronary interventions. The knowledge of plaque composition may be useful in guiding the choice of the device to be used to obtain a larger acute luminal gain.

[Advantages and controversies regarding physiologic electrostimulation of the heart in sinus node disease]. / Korzysci i kontrowersje tzw. fizjologicznej elektrostymulacji serca w chorobie wezla zatokowego.

UNLABELLED: Pacing mode in sinus node disease (SND) is one of controversies in cardiac pacing. We evaluated atrial pacing mode (AAI) in SND patients (pts). Between 1985 and 1994 AAI pacemaker was inserted in 179 pts due to symptomatic SND of varied etiology. RESULTS: The majority of pts (91.6%) were free from syncopal episodes after AAI implantation, in 15 pts (8.4%) syncopes were occasionally observed due to disturbances in pacemaker function, AVB III degrees, vaso-vagal syndrome, orthostatic hypotonia or atherosclerotic insufficiency of the cerebral circulation. In 49 (51%) out of 96 pts with brady-tachy syndrome (BTS), episodes of supraventricular tachyarrhythmia were not observed after AAI insertion and in the majority of the remaining pts the frequency of the episodes decreased significantly. Chronic atrial fibrillation developed in 5 (5.2%) pts. In some of the pts the symptoms related to chronic heart failure decreased or disappeared. A reoperation was performed in 44 (24%) pts due to electrode dislocation or fracture, atrio-ventricular conduction disturbances, an increase in pacing threshold or due to local infections. During the follow-up period 13 (7.3%) pts died of reasons unrelated to cardiac pacing therapy. CONCLUSION: In the majority of SND pts AAI pacing mode prevents from syncopal episodes caused by sinus node disfunction. It decreases the symptoms of heart failure in SND pts and stabilizes the sinus rhythm in the majority of BTS pts. Complications accompanying AAI do not post a major threat for the pts and can be easily resolved. They should by no means discourage from AAI implantation in SND.

Influence of plaque morphology on the mechanism of luminal enlargement after directional coronary atherectomy and balloon angioplasty.

OBJECTIVE: To relate the mechanism of luminal gain after directional atherectomy and balloon angioplasty to the morphological characteristics of the coronary lesions, assessed by intravascular ultrasound imaging. DESIGN: Intravascular ultrasound imaging was performed before and after the revascularisation procedure to assess the contribution of wall stretching and plaque reduction in luminal gain. SUBJECTS: 32 patients undergoing balloon angioplasty and 29 undergoing directional coronary atherectomy. MAIN RESULTS: The main luminal area in vessels treated by balloon angioplasty increased from 1.51 (SD 0.30) to 3.91 (1.09) mm2 (P < 0.0001) with a concomitant increase in total vessel area from 11.44 (2.73) to 13.07 (2.83) mm2 (P < 0.0001). Therefore stretching of the vessel wall accounted for 68% of the luminal gain while plaque reduction accounted for the remaining 32%. This mechanism ranged from 45% in non-calcific plaques to 81% in echogenic plaques. The main luminal area in vessels treated by directional atherectomy increased from 1.49 (0.32) to 4.68 (1.73) mm2 (P < 0.0001), with a concomitant increase of total vessel area from 13.61 (4.67) to 15.2 (4.04) mm2 (P = 0.006). Thus stretching of the vessel wall accounted for 49% of the luminal area gain and plaque reduction for the remaining 51%. The presence of calcium influenced the relative contribution of these two mechanisms to the final luminal gain after directional atherectomy, since in calcific plaques stretching of the vessel wall accounted for only 9% of the luminal gain as compared to 56% in non-calcific plaques. After balloon angioplasty there was greater evidence of coronary dissections (32% v 3% after directional atherectomy, P < 0.01) and plaque fissure (60% v 0%, P < 0.01). Plaque fissure was more frequently seen in echolucent and concentric lesions, whereas dissections prevailed in echogenic and eccentric lesions. CONCLUSIONS: Intravascular ultrasound imaging may allow the assessment of acute changes in lumen and vessel wall after revascularisation procedures, and help in evaluating the potential effect of the structure and morphology of coronary lesions on the mechanism of luminal enlargement.

Intensity modulation in antiresonant reflecting optical waveguides.

I provide a theoretical analysis of the refractive-index dependence of attenuation in antiresonant reflecting optical waveguides. The results are used to explain the mechanism of the intensity modulation in antiresonant reflecting optical waveguide structures, in terms of both reflection and interference phenomena in the cladding system.

[Left ventricular stroke volume in individuals with dual chamber pacemaker (DDD). Effect of atrioventricular delay]. / Objetosc wyrzutowa lewej komory serca u osob z wszczepionym stymulatorem typu DDD. Wplyw czasu opóznienia przesionkowo-komorowego.

UNLABELLED: Programming of atrioventricular delay in patients with dual chamber pacemaker is very important for left ventricular filling and has a consequence for its stroke volume. The aim of this study was to evaluate the influence of atrioventricular delay for left ventricular stroke volume during pacing at two different rates. The study was performed in 36 patients with DDD pacemaker aged from 30 to 81 years, mean 56.1 +/- 14.6. Using Doppler echocardiography we have assessed left ventricular stroke volume during two pacing rates (70 and 100 ppm) with four atrioventricular delays (100, 150, 200 and 250 ms). We have found statistically significant difference between stroke volume with various atrioventricular delays. During pacing rate of 70 ppm the maximal difference was 19% and 15% during 100 ppm. Comparing both pacing rates the distributions of hemodynamically optimal atrioventricular delays was also significantly different. The best atrioventricular delay from the hemodynamic point of view was 36 ms longer during 70 ppm of pacing rate than during 100 ppm (p = 0.0009). The most often optimal delay at 70 ppm was 190-200 ms, and the rarest optimal delay was 90-100 ms; during 100 ppm pacing respectively: 140-150 ms and 240-250 ms. We have observed considerable personal variability in the hemodynamic response for atrioventricular delay changing as well as in the hemodynamically optimal values of this parameter during both pacing rates. CONCLUSIONS: 1. Atrioventricular delay programming has significant influence on left ventricular stroke volume. 2. Programming of atrioventricular delay should be performed individually in every patient because of personal variability of optimal values of this parameter.(ABSTRACT TRUNCATED AT 250 WORDS)