Third-generation laser balloon ablation for atrial fibrillation treatment: a multicenter experience

Background

Laser balloon ablation is a promising option for performing pulmonary vein isolation (PVI) which is the cornerstone of invasive atrial fibrillation (AF) treatment.

Purpose

We aimed to investigate the acute efficacy and safety of the novel third-generation of the laser balloon system in an initial multicenter experience.

Methods

First and consecutive patients who underwent PVI with LB3 for drug-resistant paroxysmal or persistent AF at 7 Italian sites were included in this analysis. Study endpoints were acute procedural efficacy, defined as successful isolation of all identified PVs without radiofrequency touch-up, total and fluoroscopy times, and periprocedural complications.

Results

Our population included 86 patients (81% males, mean age 60.6±9.5 years) who underwent a procedure of PVI using LB3 between June 2020 and March 2021.

Most patients had paroxysmal AF (74%) and were in sinus rhythm at the beginning of the procedure. The mean procedure time was 138±60 min; fluoroscopy time was 22±17 min and the mean ablation time was 44±40 min. Of the 313 targeted PVs, 311 (99.4%) could be isolated with first-pass LB3 application, while 2 (0.6%) required radiofrequency touchup. At the end of the procedure, all patients were in sinus rhythm and 26 (32%) received electrical cardioversion to achieve stable sinus rhythm.

The total rate of major compilations was 1.2% (1/82 patients): one pericardial tamponade requiring epicardial puncture. No surgical intervention was necessary, and the patient recovered without any sequalae. There were no vascular access complications or phrenic nervy palsy. Three pinhole balloon raptures (3.5%) were observed during energy applications that required replacement of the whole system but had no effect on patient safety.

Conclusions

In a first multicenter experience, the LB3 system for PVI was safe with excellent acute efficacy.

Funding Acknowledgement

Type of funding sources: None.

Henoch-Schönlein purpura in a patient with bowel bypass syndrome

Henoch-Schönlein purpura (HSP) is a common vasculitis being characterized by the classic tetrad of nonthrombocytopenic palpable purpura, arthritis or arthralgias, gastrointestinal and renal involvement. Antigen-antibody (IgA) complexes activate the alternative complement pathway, resulting in inflammation and small vessels vasculitis. We present the case of a 53 years old Italian woman with HSP who was previously hospitalized for purpura skin lesions of the lower legs and diarrhea; a skin biopsy showed a leukocytoclastic vasculitis with perivascular accumulation of neutrophils and mononuclear cells. She was treated with immunosuppressive therapy. After 8 months she was hospitalized again for a recurrent episode of purpura skin lesions of the lower legs. At age 49 she was affected by obesity (BMI = 41.6 Kg/m2), treated via a bilio-pancreatic diversion that led, within a year, to a BMI reduction (25 Kg/m2). We suppose that bariatric surgery played a role on the development of autoimmune phenomena and that the formation of immunecomplexes is secondary to the excess of intestinal bacterial antigens. A cyclic therapy with Paromomicine 500 mg twice daily and Metronidazole 250 mg twice daily was performed with a clear up of the clinical picture. In medical literature are described numerous complications which include arthritis, erythema nodosum-like lesions, eruptions and other skin manifestations in patients who have undergone jejunocolic bypass. This case report describes for the first time the presence of HSP in a patient with bowel bypass syndrome and it is also able to demonstrate the relationship between the intestinal bacterial overgrowth and the systemic autoimmune system.

Post automatic implantable cardioverter defibrillator implant therapies: drugs and ablative techniques

The aim of this article is to report the evidences about the use of drugs and ablation after implantation of a cardioverter defibrillator. Drugs can be utilized to prevent appropriate and inappropriate shocks, can influence positively or negatively defibrillation threshold, can be useful for the treatment of electrical storm. Ablation can be performed for direct cure of coexisting atrial and ventricular tachyarrhythmias or for AV node modulation. In particular, previous data demonstrate that rescue ventricular tachycardia ablation of drug-refractory electrical storm is possible by a substrate-orientated ablation approach even in patients with complex chronic infarction and various ventricular tachycardias. At the end of this article it is described how remote monitoring, a new very promising technical improvement, can be utilized for deciding, almost in real time, the use of both these therapies or for controlling their efficacy.

Is implantable defibrillator indicated in all patients on cardiac resynchronization therapy?

Implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) have been introduced during the recent years to improve survival, decrease hospital readmissions and mortality, and to improve functional status and quality of life for patients with heart failure and left ventricular systolic dysfunction (LVSD). Studies which evaluated the use of CRT or ICD alone or compared CRT with CRT-ICD in patients with heart failure and LVSD are listed in this article. The results obtained are already influencing clinical practice in the US, where it has been estimated that 90% of patients receiving a CRT device now are being implanted with an ICD component. However, it is still today debated whether patients with LVSD and heart failure should be routinely offered a CRT-ICD. In fact, there are some issues that still should be solved before to establish indication for CRT-D in all heart failure patients with an indication for CRT: 1) a non complete agreement among the different societies which wrote recommendations for guidelines (a comparative table is reported); 2) a better identification of implantable patients and an amelioration of utilized devices; 3) economic and ethical ramifications of this therapy. Anyway still now the crucial question is: ''Can resynchronization be done in isolation or must be accompanied by an ICD device?''. To answer to this question we can only express which is, in our opinion, the actual position of many physicians who work in the field of pacing and electrophysiology: ''The lesson to be learned is that we still can not predict surely which patient will die of sudden death. Until a method of identifying the high risk patients can be developed, the safest strategy should be to advise a combined ICD-CRT device for patients with indication for CRT''.

Role of natriuretic peptides in heart failure patients with special reference to those on cardiac resynchronization therapy

In recent years natriuretic peptides (NPs) have emerged as important tools for evaluation of heart failure patients. Since its approval by the Food and Drug Administration (FDA) in November 2000, recent surveys suggest that approximately 83% of hospitals in the US use some type of NP testing. Although NP testing was originally focused on rapid diagnosis of patients presenting to the emergency department with shortness of breath, clinicians regularly look to NPs for diagnosing minimally symptomatic or asymptomatic left ventricular dysfunction, and using NPs levels in clinic to help ascertain when decompensation is present. NP testing is now included in the guidelines for the diagnosis and treatment of chronic heart failure and in the Italian Consensus Document for the clinical use of NPs. Recommendations indicate that assessment of NPs can be considered a reliable rule-out test of heart failure in primary care and in the emergency room even if they stated that the role for treatment monitoring or for prognostic evaluation needs to be determined. In recent years, cardiac resynchronization therapy (CRT) was introduced as a new treatment modality for patients with systolic heart failure and several studies suggest that plasma concentration of NPs ensues as a very useful parameter for evaluating and monitoring patients who undergo CRT. Thus this article aims not only to summarise data concerning NPs measurement in patients with heart failure, but also to indicate how these markers could be utilized in the future to objectively assess effects of CRT (identification of responders). In conclusion, if further studies will confirm above mentioned remarks, it would be possible that NPs evaluation can help to tailor the more suitable therapy for each heart failure patient and, therefore, to reduce the number of failures.

Aggressive eosinophilic granuloma of the parietal bone. An immunohystochemical study of Ki-67 expression

Solitary eosinophilic granuloma (EG) of the skull is a rare lesion, the natural history of which is still to be defined. We report a case of a 26-year-old female who presented with progressive headache and nausea accompanied by a painful firm mass in her left parietal region, which grew very rapidly during the last two weeks before admission. Computed tomography scan showed an osteolytic lesion, which on magnetic resonance imaging appeared hyperintense on both T1- and T2-weighted images, with marked and heterogeneous enhancement after gadolinium administration. Total surgical excision of the lesion was performed and histopathological diagnosis was compatible with eosinophilic granuloma. Immuno-histochemical study of Ki-67 antigen expression was also performed with a labelling index of 10%. In a review of the pertinent literature, we found one case report showing a Ki-67 labelling index of 6.2% in a patient harboring EG of the occipital bone. These two relatively high percentages of proliferative activity suggest a role of local Langerhans'cell proliferation, along with that of inflammatory response, in the aggressive clinical course and rapid expansion observed in some rare cases of solitary eosinophilic granuloma.

Resynchronization of mitral valve annular segments reduces functional mitral regurgitation in cardiac resynchronization therapy

AIM

Cardiac resynchronization therapy (CRT) reduces the severity of functional mitral regurgitation (FMR) in patients with heart failure and left bundle branch block. Our hypothesis was that the induction of a more synchronous mitral valve anulus contraction can be a mechanism of FMR reduction in CRT patients.

METHODS

An echo tissue Doppler imaging (TDI) examination was performed at baseline and 6 months after biventricular pacing system implant in 30 patients (4 females and 26 males, 74.1+/-6.1 years) with dilatative or ischemic chronic heart failure, NYHA class = or >III, ejection fraction (EF) = or <35% and QRS = or >140 ms. EF, Myocardial Performance Index (MPI), left end-diastolic and systolic volumes (LVEDV, LVESV), mitral regurgitation jet area/left atrial area (JA/LAA), effective regurgitant orifice area (EROA), mitral anulus contraction (MAC) were evaluated. Using TDI, at the 6 left ventricle (LV) basal segments the time to the peak myocardial sustained systolic velocity (Ts) and the standard deviation (SD) of TS were evaluated.

RESULTS

At 6 months follow-up NYHA class, EF, MPI were significantly improved, LV volumes were reduced. FMR degree, evaluated both as JA/LAA and EROA, was significantly reduced. This effect was associated with the 6 basal segments resynchronization and with a more effective annular contraction.

CONCLUSIONS

Our data show that CRT by resynchronizing left ventricular basal segments produces a more effective mitral valve annulus contraction and contributes to FMR improvement. Further studies need to evaluate if this could be taken into account as new therapeutic perspective of functional mitral valve regurgitation.

Clinical evaluation of disorganization during atrial fibrillation as a guide to radiofrequency ablation

Aim of this study was to investigate the spatial patterns of organization of fibrillation in the right atrium using bipolar recordings from a basket catheter. Study population consists of 17 patients with persistent atrial fibrillation (AF), selected a priori for low energy internal cardioversion. Organization was measured by the number of occurrences--i.e. the percentage number of points laying on the baseline--which has been demonstrated to match Wells' criteria for the classification of AF. Well-defined and stable patterns of organization characterize the electrical activity of the right atrium in these patients. The organization in the entire right atrium showed an individual rather than common distribution. This may have implications in the choice of regions candidate for ablation.

Randomized crossover comparison of right atrial appendage pacing versus interatrial septum pacing for prevention of paroxysmal atrial fibrillation in patients with sinus bradycardia

BACKGROUND

New atrial pacing techniques and overdrive pacing algorithms have been introduced to prevent atrial fibrillation. This study was designed to test the hypotheses that (1) interatrial septum pacing (IASP) at the triangle of Koch would be more effective than right atrial appendage pacing (RAAP) in preventing paroxysmal atrial fibrillation (PAF) in patients with sinus bradycardia and (2) an algorithm (CAP) designed to achieve constant atrial capture would increase the efficacy of rate-responsive atrial pacing.

METHODS

We studied 46 patients with PAF and sinus bradycardia implanted with a DDD(R) (Medtronic Thera) pacemaker. Twenty-four patients (6.0 +/- 10.1 PAF episodes/month within 3 months before study) were randomized to RAAP and 22 patients (5.4 +/- 7.1, not significant) to IASP. Within each arm 2 randomized crossover periods of CAP-OFF and CAP-ON function were programed.

RESULTS

The PAF episodes per month significantly decreased in the RAAP (CAP-OFF: 2.1 +/- 4.2, P <.05; CAP-ON: 1.9 +/- 3.8, P <.05) and in the IASP group (CAP-OFF: 0.2 +/- 0.5, P <.05; CAP-ON: 0.2 +/- 0.5, P <.05). Values were significantly lower in the IASP group than in the RAAP group in both CAP-OFF (0.2 +/- 0.5 vs 2.1 +/- 4.2, P <.05) and CAP-ON (0.2 +/- 0.5 vs 1.9 +/- 3.8, P <.05) conditions. PAF burden was significantly lower in the IASP than in the RAAP group in CAP-OFF (47 +/- 84 min/d vs 140 +/- 217, P <.05) and in CAP-ON (41 +/- 72 vs 193 +/- 266, P <.05) conditions. No differences were observed within each arm in PAF burden between the 2 crossover CAP programing periods.

CONCLUSIONS

Rate-adaptive IASP at the triangle of Koch is more effective than RAAP in preventing PAF in patients with sinus bradycardia. In our sample of patients no additional clinical benefit is furnished by the CAP algorithm.

Increased cardiac sympathetic activity and insulin-like growth factor-I formation are associated with physiological hypertrophy in athletes

Physiological hypertrophy represents the adaptive changes of the heart required for supporting the increased hemodynamic load in regularly trained healthy subjects. Mechanisms responsible for the athlete's hypertrophy still remain unknown. In 15 trained competitive soccer players and in 15 healthy men not engaged in sporting activities (sedentary control subjects) of equivalent age, we investigated the relationship among cardiac growth factor formation, cardiac sympathetic activity, and left ventricular morphology and function. Cardiac formation of insulin-like growth factor (IGF)-I, endothelin (ET)-1, big ET-1, and angiotensin (Ang) II was investigated at rest by measuring artery-coronary sinus concentration gradients. Cardiac sympathetic activity was studied by [(3)H]norepinephrine (NE) kinetics. Cardiac IGF-I, but not ET-1, big ET-1, and Ang II, formation was higher in athletes than in control subjects (P<0.01). NE levels in arterial and peripheral venous blood did not differ between groups. In contrast, coronary sinus NE concentration was higher in athletes than in control subjects (P<0.01). Cardiac, but not total systemic, NE spillover was also increased in athletes (P<0.01), whereas cardiac [(3)H]NE reuptake and clearance were not different. Echocardiographic modifications indicated a volume overload-induced hypertrophy associated with increased myocardial contractility. Multivariate stepwise analysis selected left ventricular mass index as the most predictive independent variable for cardiac IGF-I formation and velocity of circumferential fiber shortening for cardiac NE spillover. In conclusion, increased cardiac IGF-I formation and enhanced sympathetic activity selectively confined to the heart appear to be responsible for the physiological hypertrophy in athletes performing predominantly isotonic exercise.

Mapping the organization of atrial fibrillation with basket catheters. Part II: Regional patterns in chronic patients

The aim of this study was to investigate the spatial patterns of organization of fibrillation in the right atrium using bipolar recordings from a basket catheter in a population of 17 patients with persistent AF. The number of occurrences (NO) (i.e., the number of points laying on the baseline) was used as an objective measure of organization. This parameter significantly matches Wells' criteria for the classification of bipolar recordings during AF. The anatomic correspondence of the splines with eight atrial regions (namely anterior free wall, lateral free wall, posterolateral free wall, posterior free wall, posterior atrial septum, atrial septum, tricuspid valve, and anterior tricuspid valve) was assessed by fluoroscopic projections and electrogram morphology. Each region was further divided into high, mid-high, mid-low, and low segments. It was observed that individual and well-defined patterns of organization characterize the electrical activity of the right atrium in patients with persistent AF. When observed over 10 minutes, these patterns are rather stable in time. In each patient, the NO measurements were significantly different in the various right atrium regions (P < 0.0001 for all patients, Friedman test). The NO averaged over the population was significantly different among the regions (P < 0.001, Kruskal-Wallis test), owing to a common disorganized pattern observed in the tricuspid valve and anterior tricuspid valve regions. When these regions were removed from the analysis, the differences among the remaining regions were not statistically significant (P = 0.77). In conclusion, the quantitative assessment of organization in the entire right atrium showed an individual rather than common distribution. This may have implications in the choice of regions candidate for ablation.

Altered values of heart rate variability in patients with relapse of atrial fibrillation during the first week after electrical cardioversion: preliminary data

BACKGROUND

It has not so far been elucidated whether the autonomic nervous system plays a role in the pathogenesis of atrial fibrillation relapse after electrical cardioversion.

METHODS

In 40 consecutive patients with atrial fibrillation (22 males, 18 females, mean age 60 +/- 2 years) submitted to successful electrical cardioversion (external in 26 and low-energy internal in 14) we evaluated the heart rate variability (24-hour Holter recording) immediately after restoration of sinus rhythm in order to assess the cardiac sympatho-vagal drive.

RESULTS

Patients with atrial fibrillation relapse within the first week of electrical cardioversion were characterized by a significantly higher low/high frequency ratio.

CONCLUSIONS

Despite the heterogeneity of the studied population (concerning both the therapy and etiology of atrial fibrillation), our data strongly suggest that the evaluation of the low/high frequency ratio by means of power spectral analysis immediately after electrical cardioversion is a useful tool for the identification of those patients who are prone to atrial fibrillation recurrence. Our conclusions are supported by the finding of high positive and negative predictive values for the low/high frequency ratio both in the 24-hour period and during daytime.

Inhibition of AChE: structure-activity relationship among conformational transition of Trp84 and biomolecular rate constant

In this study the authors attempt to correlate kinetic constants for carbamylation of AChE, by a series of carbamate inhibitors, with the conformational positioning of Trp84 in transition state complexes of the same carbamates with Torpedo AChE, as obtained by computerized molecular modelling. They present evidence for changes in the distance of the carbamates from the center of the indole ring which can be correlated with the bimolecular rate constants for inhibition. As a result the greater the distance from Trp84, the smaller the bimolecular inhibition constant value, ki (= k2/Ka), becomes. In conclusion, the value of the bimolecular rate constant for selected AChE inhibitors (structural changes that have been hypothesised or natural alkaloids of unknown activity) which possess similar size and rigidity, can be obtained. Under these conditions energy minimization alone seems to be sufficient even to accurately predict protein-substrate interactions that actually occur. Modelling studies also suggest that conformational re-orientation of Trp84 in the transition state could produce an overall movement of the Cys67-Cys94 loop.

Prevention of short term reversible chronic atrial fibrillation by permanent pacing at the triangle of Koch

OBJECTIVES

The purpose of this study was to investigate if single lead interatrial septum pacing could be effective in maintaining sinus rhythm in patients in whom restoration of sinus rhythm was only possible for a period of 2-24 hours after one or more previous electrical cardioversions, and in whom a sinus bradycardia was documented before arrhythmia restarted. The two hours limit was chosen because it was considered a sufficient time to implant a dual chamber pacemaker.

BACKGROUND

Alternative atrial pacing techniques have been demonstrated to be successful in preventing recurrences of atrial fibrillation (AF) in patients with sinus bradycardia. Excluding the AF occurring after only a few sinus beats, at 24 hours from electrical cardioversion an early restart of chronic AF has been reported in 12% to 17% of the patients.

METHODS

After sinus rhythm was restored by internal electrical cardioversion, 17 patients, 7 ablated at the AV junction, underwent a dual chamber rate response (DDDR) pacemaker implantation with a screw-in atrial lead placed in the interatrial septum.

RESULTS

After a follow-up period of 17+/-5 months (range 12 to 27 months) persistence of sinus rhythm was observed in 11 patients (65%). Six patients (35%) had recurrences of paroxysmal attacks, while five (30%) were totally free of AF. Recurrence of chronic AF was observed in six cases (35%) after 2 days-12 months from implantation. No dislodgements of the atrial lead and no complications were observed at implantation and during follow-up.

CONCLUSIONS

Interatrial septum pacing is a safe and feasible technique with a satisfying success rate (65%) in long-term maintaining sinus rhythm in previously unsuccessfully cardioverted patients.

Should stimulation therapy for congestive heart failure be combined with defibrillation backup?

Biventricular pacing has been proposed to resynchronize ventricular contraction in patients with congestive heart failure (CHF) and interventricular conduction delay. However, the sudden death rate is still high despite the improvement in cardiac performance. Devices combining biventricular pacing with implantable cardioverter defibrillator (ICD) backup are now under clinical investigation to demonstrate whether they can decrease sudden death. From the first implant of an ICD with biventricular transvenous pacing on August 1998 to April 2000, 96 patients underwent such implants: 67 (70%) received pacemakers alone and 29 (30%), who had class I ICD indications, received combined pacemaker/ICD systems. During a mean follow-up of 283 +/- 170 days, 13 (14%) patients died: 5 of 29 (17%) in the ICD group and 8 of 67 (12%) in the pacemaker group. A total of 15 patients (52%) had ICD shocks and 6 patients (21%) had 113 episodes of ventricular tachyarrhythmias, of which 96 (85%) were converted to sinus rhythm with antitachypacing. The echocardiograms showed a narrowing of the delay between the onset of right and left ventricular outflow from 40 +/- 37 msec to 17 +/- 16 msec (p = 0.03) and a reduction of the mitral regurgitation area from 7 +/- 3.8 cm2 to 5 +/- 4 cm2 (p = 0.04) at 3 months. Functional class improved from 2.8 +/- 0.7 to 1.6 +/- 0.5 (p <0.001) 3 months after implant. Thus, ischemic patients with reduced left ventricular ejection fraction and ventricular tachyarrhythmias seem good candidates for biventricular pacing with ICD backup. The sudden death risk for those with idiopathic dilated cardiomyopathy, however, is difficult to stratify, and the choice of ICD backup has to be considered on the basis of patient safety, as well as of costs.

Atrioventricular interval optimization in the right atrial appendage and interatrial septum pacing: a comparison between echo and peak endocardial acceleration measurements

Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO). Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 +/- 23 ms, 177 +/- 19 ms, and 192 +/- 23 ms in DDD and 147 +/- 19 ms, 135 +/- 27 ms, and 146 +/- 20 ms in VDD, respectively. OAVD measured by LVFT, CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001). In group B, OAVD measured by LVFT, CO, and PEA was 116 +/- 19 ms, 113 +/- 10 ms, and 130 +/- 30 ms in DDD and 106 +/- 16 ms, 96 +/- 15 ms, and 108 +/- 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO.

Interatrial septum pacing: a new approach to prevent recurrent atrial fibrillation

BACKGROUND

There are a variety of approaches to the prevention of atrial fibrillation (AF) with pacing. Aim of this study was to test the safety and feasibility of interatrial septum pacing at the posterior triangle of Koch for AF prevention and to exclude potential arrhythmic effects.

MATERIAL AND METHODS

Interatrial septum pacing was performed in 34 patients (21 males, 13 females, mean age 69 +/- 12 years): 9 without a history and clinical evidence of atrial fibrillation (AF) (6 with sinus bradycardia, 2 with second-degree AV block, and 1 with carotid sinus hypersensitivity) and 25 with sinus bradycardia and paroxysmal atrial fibrillation (PAF) (mean symptomatic episodes/month 6.2 +/- 10). In all patients a screw-in bipolar lead was positioned in the interatrial septum superiorly to the coronary sinus.

RESULTS

At implant the mean P wave amplitude was 2.5 +/- 1.5 mV, the pacing threshold was 1 +/- 0.6 V and the impedance was 907 +/- 477 Ohm. Mean P wave duration was 118 +/- 17 ms in sinus rhythm and 82 +/- 15 during interatrial septum pacing (p < 0.001). During a mean follow-up period of 10 +/- 7 months, no patients without atrial tachyarrhythmias before implantation experienced AF. During a 9 +/- 6 months follow-up we observed only 2 symptomatic arrhythmia recurrences between AF patients (mean symptomatic episodes/month 0.006 +/- 0.0022) (p < 0.01 vs before implant period).

CONCLUSIONS

Our data indicate that interatrial septal pacing is safe and feasible. A significant less incidence of arrhythmic episodes has been observed during follow-up. Further controlled randomized prospective studies are necessary to establish the exact role of this technique respect to conventional or multisite stimulation when patients with paroxysmal AF need to be permanently paced.

[Vesico-ureteral reflux: diagnostic and therapeutic procedures]

The vesico ureteral reflux (VUR) is the most common uropathy associated to urinary tract infections (UTI). The identification of V.U.R. is very important to avoid reflux nephropathy and it's complications. To avoid the exposure to unnecessary and injurious x-rays, the authors propose patient selection based on the presence or absence of distal ureteral dilatation and on the time elapsed between typical or atypical symptoms of u.t.i. and fever. First of all, it is essential to diagnose pielonephritis. After ultrasound and radionuclide scintigram with DMSA they select the infants who need cystourethrography. The infants with V.U.R. undergo antibiotic prophylaxis until spontaneous or surgical recovery. The duration of prophylaxis depends on the degree of V.U.R. and the age of the infant at diagnosis.

Anionic binding site and 2,3-DPG effect in bovine hemoglobin

It is generally believed that bovine hemoglobin (BvHb) interacts weakly with 2,3-diphosphoglycerate (2,3-DPG) in a chloride-free media and not at all in the presence of physiological concentrations of chloride (100 mM). This lack of interaction has raised several questions at both structural and evolutionary levels. Results obtained in this study via 31P nuclear magnetic resonance (NMR) show that, even in the presence of 100 mM chloride ions, 2,3-DPG does, in fact, interact with bovine deoxy-Hb. This spectroscopic observation has been confirmed by oxygen binding experiments, which have also shown that, under certain conditions, chloride and 2,3-DPG may display a synergistic effect in modifying the oxygen affinity of bovine hemoglobin. It could be that this synergistic effect has its structural basis in a conformational modification induced by 2,3-DPG, possibly causing extra chloride anions to approach the positive charges which constitute the anion binding site. Another possibility, not necessarily an alternative, is the additional chloride binding site recently identified [Fronticelli, C., Sanna, M. T., Perez-Alvarado, G. C., Karavitis, M., Lu, A.-L., and Brinnigar, W. S. (1995) J. Biol. Chem 270, 30588-30592] involving lysine beta76 that in bovine Hb substitutes for the alanine residue present in human hemoglobin. All of these findings are in agreement with the very low enthalpy of oxygenation that characterizes bovine Hb when both chloride and 2,3-DPG are present in concomitance. The results reported here clearly show that bovine hemoglobin does react with 2, 3-DPG and is functionally affected by this organic phosphate. Hence, the very low intraerythrocytic concentration of 2,3-DPG (0.5 mM) in adult bovine red blood cells is the result of metabolic adaptation which cannot be explained solely by the different amino acid sequence at the level of the 2,3-DPG binding site.

The role of TRP84 in catalytic power and the specificity of AChE

The structure-function relationship between the alkaloids physostigmine, physovenine and the three structurally related compounds were investigated by employing kinetic studies and molecular modeling. Crystallographic data from the X-ray conformation of the Torpedo californica acetylcholinesterase complex together with the transition state analog inhibitor m-(N,N,N,-Trimethylammonio) trifluoroacetophenone (TMTFA) was used as template onto which inhibitors were superimposed. Among the structural elements of the active site, TRP84 residue shows a versatile role. In fact, its aromatic electrons not only can be employed in pi-cation interactions, as is the case for ACh, but they can also provide a polarizable surface for van der Waals and London interactions.

The impact of ratee's disability on performance judgments and choice as partner: the role of disability-job fit stereotypes and interdependence of rewards

An experiment assessed the impact of disability-job fit stereotypes and reward interdependence on personnel judgments about persons with disabilities. Students (N = 87) evaluated 3 confederates. The experiment varied disability of the target confederate (dyslexia vs. nondisabled), task, and dependence of rater rewards on partner performance. Two disability-task combinations represented stereotypical poor fit and good fit. Dependent variables were performance evaluations, performance expectations, and ranking of target as a partner. There was negative bias against the confederate with dyslexia in poor-fit conditions. In the interdependent reward condition, there was a negative main effect for disability, regardless of fit. No effects for disability were found on performance ratings or expectations. Results indicate the need to consider disability-job fit stereotypes and consequences to raters when assessing the impact of disability on personnel judgments.

The impact of ratee's disability on performance judgments and choice as partner: the role of disability-job fit stereotypes and interdependence of rewards

An experiment assessed the impact of disability-job fit stereotypes and reward interdependence on personnel judgments about persons with disabilities. Students (N = 87) evaluated 3 confederates. The experiment varied disability of the target confederate (dyslexia vs. nondisabled), task, and dependence of rater rewards on partner performance. Two disability-task combinations represented stereotypical poor fit and good fit. Dependent variables were performance evaluations, performance expectations, and ranking of target as a partner. There was negative bias against the confederate with dyslexia in poor-fit conditions. In the interdependent reward condition, there was a negative main effect for disability, regardless of fit. No effects for disability were found on performance ratings or expectations. Results indicate the need to consider disability-job fit stereotypes and consequences to raters when assessing the impact of disability on personnel judgments.

Classical risk factors and emerging elements in the risk profile for coronary artery disease

The prevention of coronary artery disease is based on the control of several factors associated with a disease or clinical condition and suspected to play a pathogenetic role, defined as 'risk factors'. Smoking is a powerful risk factor for coronary artery disease, with risk of events increasing in relation to the number of cigarettes smoked daily. Smoking cessation is associated within 3-4 years, with a significant reduction in cardiovascular risk. Hyperlipidaemia is a powerful predictor of coronary disease with a strong, independent, continuous and graded positive association between cholesterol levels and risk of coronary events. Several large studies have shown the benefit of cholesterol reduction, and there is clear evidence of the efficacy of statins in the reduction of events in primary and secondary prevention. Hypertension is a significant, strong and independent risk factor for coronary artery disease morbidity and mortality and the reduction of events and mortality by antihypertensive treatment is well documented. Obesity is associated with an increase in all-cause mortality and cardiovascular mortality, with a particularly high risk for subjects with central obesity. Central obesity is also part of the so-called 'metabolic X syndrome' including insulin resistance, which appears to be associated with a particularly high risk of coronary artery disease. Type 1 and type 2 diabetes mellitus are associated with an increased risk of cardiovascular disease, especially in women. Several studies have shown that good metabolic control and multifactorial risk factor reduction significantly lower the coronary risk in these patients. Recent evidence is accumulating that some clotting factors (fibrinogen, factor VII, von Willebrand factor) and fibrinolytic factors (t-PA and PAI-1) are associated with an increased risk of coronary artery disease. The European Concerted Action on Thrombosis (ECAT) showed that the levels of fibrinogen, von Willebrand factor antigen, and t-PA antigen are independent predictors of subsequent coronary syndromes in patients with angina pectoris, and that low fibrinogen is associated with a low risk of events despite high cholesterol levels. Post-menopausal status is associated with increased risk of coronary artery disease, particularly when menopause is premature (before the age of 45) or abrupt (surgical). There is strong, thought not yet completely definite evidence that post-menopausal hormone replacement therapy may significantly reduce the risk of events and improve survival. Hyperhomocysteinaemia is an emerging risk factor independently associated with an increased risk of coronary artery disease, cerebral vascular disease, and peripheral vascular disease. The administration of vitamin B6, B12 or folate seems to be useful and is currently under further evaluation. Recently, attention has been focused on the correlation between coronary artery disease and genetic factors, such as ACE gene polymorphism or the gene polymorphism for the IIIa-moiety of the platelet fibrinogen receptor IIb-IIIa. In primary prevention, control of the major risk factors mainly in patients with clustered factors will substantially reduce the risk of ischaemic events. Secondary prevention of CHD is based on: aggressive behavioural advice, blood pressure reduction in hypertensives, good metabolic control of diabetes, and cholesterol reduction. Aspirin, beta-blockers, ACE inhibitors, and oral anticoagulants, may be useful in selected patients.

Evaluation of clotting and fibrinolytic activation after protracted physical exercise

The behavior of hemostatic system activation during protracted physical exercise is well known, but the duration of its modification is not yet defined. In order to evaluate the time of hemostatic system activation after prolonged strenuous endurance physical exercise (typical marathon race: 42.195 km, v=15.35 km/h; mean length of time run 2.45+/-0.15 hours) 12 well-trained long-distance male runners (mean age: 35+/-7, range 25-47 years) were investigated. Blood samples were drawn in the morning on the day before the performance, immediately after the race, and 24 hours and 48 hours after the end of run. With respect of baseline, immediately after the race, a significant decrease of fibrinogen (-25%) and significant increases of prothrombin fragment 1+2 (+633%) and thrombin-antithrombin complex (+848%) were observed. A significant acceleration of euglobulin lysis time (-41%), and rises of plasma levels of tissue plasminogen activator antigen (+361%), plasminogen activator inhibitor type 1 antigen (+235%), d-dimer (+215%), and plasma fibrinogen degradation products (+1200%) were also found. Only a slight, yet not significant, decrease in plasminogen activator inhibitor type 1 activity was observed. One day after the end of marathon different parameters were still unchanged. Forty-eight hours after the competition all parameters investigated returned to baseline values. These results indicate a persistence of clotting as well as fibrinolysis activation up to 24 hours after the end of the race.

Studies on a new series of THA analogues: effects of the aromatic residues that line the gorge of AChE

A series of N-monoalkylsubstituted 1,2,3,4-tetrahydro-9-aminoacridines have been prepared after modelling simulation of the AChE-inhibitor complex. Molecular modelling has predicted a number of hydrophobic residues to be involved in the catalytic mechanism of this interaction between the binding sites of AChE and this series of aminoacridines. In these compounds the acridine moiety becomes sandwiched between the rings of PHE330 and TRP84. In particular, the alkyl chain shows the important role of aromatic groups as binding sites. Their in vitro inhibitory properties (enzyme from Electrophorus electricus) confirm the aromatic groups as a general and significant characteristic of the mechanism of AChE inhibition.

Identification of candidates for prevention of venous thromboembolism

The rationale for prophylaxis of venous thromboembolism (VTE) is based on the frequently clinically silent nature of the disease. A number of risk factors for VTE have been known for a long time, even if some of them are still controversial. Many studies have been performed in the surgical field, and have established different risk classes for VTE. Such risk stratification is especially determined by type of surgery and to some extent by personal characteristics of patients, and it defines operations at high, intermediate, and low risk for VTE. According to this classification, prophylaxis of VTE is mandatory in some cases, less useful in others. Less information is available on medical diseases, in which the clinical conditions and the intrinsic characteristics of patients determine the class of risk for VTE. Different strategies for identifying patients who should undergo prophylaxis have been proposed based on risk factor evaluation in the individual patient. However, even if such an approach may be of help for the physician, its validity is still impaired by the difficulty of taking into account all of the variables possibly involved in VTE occurrence.

[Oxygen therapy and pulmonary hypertension in chronic obstructive bronchopneumopathies]

Pulmonary hypertension has a negative prognostic value in the progression of chronic obstructive lung disease. The hypoxic vasoconstriction and subsequent morphological alterations that occur in the small arteries and in the pre-capillary arterioles may contribute to the reduction of the pulmonary vascular bed. The evolution of pulmonary hypertension in patients with chronic obstructive lung disease is not rapid except during relapses of the disease. Oxygen therapy reduces pulmonary arterial pressure values not only via a reduction in the functional abnormalities of the vessels but also via a regression in the anatomic changes induced by hypoxemia. Thus, long-term oxygen therapy may slow the progression of pulmonary hypertension in the course of chronic obstructive lung disease and the longer is oxygen administration the better haemodynamic results are obtained. The Medical Research Council (MRC) Study and the Nocturnal Oxygen Therapy Trial (NOTT) have clearly demonstrated that mortality among hypoxiemic patients treated with low-flow oxygen therapy is reduced; the NOTT also reported a reduction of about 10% in the levels of pulmonary vascular resistances in patients treated with long-term oxygen therapy, while an increase of about 7% has been observed in patients treated with oxygen therapy only during the night. Nevertheless, the reduction of mortality observed during long-term oxygen therapy not always is accompanied by an haemodynamic improvement; in particular a reduction in the pulmonary arterial pressure seems not to reduce mortality. In conclusion long term oxygen therapy may slow the progression of pulmonary hypertension during chronic obstructive lung disease while the improvement in pulmonary haemodynamic due to oxygen therapy is not strictly correlated with a reduction of mortality.

Increased number of thromboxane A2-prostaglandin H2 platelet receptors in active unstable angina and causative role of enhanced thrombin formation

The current study was designed to investigate the number and affinity of platelet thromboxane A2/prostaglandin H2 (TxA2/PGH2) receptors in patients with unstable angina and, if any, the role played by the increased thrombin formation that is a common finding in these patients. Measurements taken during active unstable angina but not those taken during inactive angina showed an increase number (p < 0.001), without changes in affinity, of platelet TxA2/PGH2 receptors, evaluated as the binding capacity of iodine 125-PTA-OH, a stable TxA2 analogue. Moreover patients with active angina had higher plasma concentrations of fibrinopeptide A (FPA) (p < 0.0001), which were significantly related to the number of platelet TxA2/PGH2 receptors (r = 0.76; p < 0.01). Heparin infusion but not aspirin treatment promptly normalized the number of TxA2/PGH2 receptors and significantly reduced plasma FPA concentrations. In an in-vitro study thrombin in a concentration similar to that found in vivo significantly increased the number of platelet TxA2/PGH2 receptors (p < 0.01), whereas heparin did not affect TxA2/PGH2 receptors. These results have important therapeutic implications and indicate the preferential use of heparin rather than aspirin during the acute phase of unstable angina.

Plasma endothelin and renal endothelin are two distinct systems involved in volume homeostasis

This study of seven healthy young subjects was designed both to establish whether endothelin-1 (ET-1) is involved in the homeostasis of blood volume and to clarify the relationship between plasma and urinary ET-1. Acute volume expansion (+17%) caused increases in venous blood pressure (+4.4 mmHg) and the plasma concentration of ET-1 (+129%) and a decrease (-99%) in the urinary excretion of ET-1. Volume depletion (-8.5%) provoked an increase in the plasma concentration of ET-1 without altering the urinary excretion of ET-1. Passive elevation of an arm resulting in a local decrease of venous blood pressure (-17 mmHg) elicited an increase of the local formation of ET-1, with a 10-fold increase in the venous-arterial gradient compared with the opposite arm, which lay at the level of the heart. The increased local formation of ET-1 was blunted by volume expansion. The results indicate that 1) plasma ET-1 and urinary ET-1 represent two different endothelin-generating systems, both of which are involved in the regulation of blood volume, and 2) plasma ET-1 appears to be an important mechanism for the long-lasting adaptations of venous wall tension to changes in blood volume.

Organizational socialization of employees with disabilities: Critical issues and implications for workplace interventions

Organizational socialization is the process whereby newcomers to work organizations become insiders. The socialization process has been linked to various outcomes including newcomer job satisfaction, organizational commitment, job knowledge and performance, promotion and advancement rate, salary, and turnover. The purpose of the present paper is threefold: (1) to examine issues facing persons with disabilities during organizational socialization in order to help guide future research on this topic; (2) to provide an awareness of potential aditional barriers (unrealistic newcomer expectations, interaction avoidance, "norm to be kind," low work group expectations) that face newcomers with disabilities as they begin jobs; and (3) to suggest some possible policies, programs, and interventions that might help persons with disabilities to overcome those barriers.

Binding kinetics and antiplatelet activities of picotamide, a thromboxane A2 receptor antagonist

1. Picotamide was shown to inhibit platelet binding of thromboxane A2 (TxA2)-mimetics and to cause a reduction of TxA2 platelet receptors after in vivo administration. The present study aimed to investigate directly [3H]-picotamide binding to human platelets and in particular the relationship between binding kinetics and antiaggregating properties. 2. [3H]-picotamide time-dependently bound to a single class of platelet TxA2 receptors with a KD of 325 nmol l-1 at equilibrium. The binding was displaceable by TxA2 analogues U46619 and ONO11120 (Ki 19 and 28 nmol l-1 respectively) but not by prostacyclin (PGI2), prostaglandin E2 (PGE2) and TxB2. Antiaggregating activity and TxA2 formation inhibition paralleled with binding kinetics. 3. By prolonging the incubation time from 30 to 120 min, picotamide showed a progressively increasing non-displaceable binding, whereas specific displaceable binding decreased in comparison to the values reached at 30 min. Non displaceable binding was specific, temperature-dependent saturable and followed a Michaelis-Menten kinetic (Vmaxapp = 130 fmol per 10(8) platelets h-1, KMapp = 330 nmol l-1). Picotamide progressively underwent a specific stable interaction with its platelet receptor. 4. In conclusion, after an initial reversible binding, a progressive stabilization of picotamide binding takes place resulting in a progressively more stable interaction with platelets.

Predictive value for thrombotic disease of plasminogen activator inhibitor-1 plasma levels

Plasminogen activator inhibitor-1 plays a major role in the fibrinolytic system as the main physiological inhibitor of both tissue-type and urinary-type plasminogen activators. The inhibitor is present in plasma in small amounts and derives mainly from endothelial cells. Positive correlations have been reported between plasma levels and different parameters, such as serum triglycerides, insulin plasma levels and body mass index. Moreover, high plasma inhibitor concentrations have been observed in different disease states, but it must be stressed that plasminogen activator inhibitor-1 behaves as an acute-phase reactant and measurement of plasma levels is not significant in the acute phase of the disease. A possible predictive value of inhibitor levels for thrombotic events such as deep vein thrombosis and ischemic heart disease has been studied. On the basis of available studies, the predictive value is not clear for venous thrombosis, whereas plasminogen activator inhibitor-1 levels can predict some coronary events, at least in subgroups of young patients with a first myocardial infarction. It remains to be established if treatments able to reduce plasma inhibitor levels lead to a decrease in the risk of thromboembolic events.

Effect of low-dose heparin treatment on fibrinolysis in patients with previous myocardial infarction

The present study was designed to investigate whether medium-term, low-dose heparin treatment is able to affect the fibrinolytic system. In a randomized cross-over study 10 asymptomatic patients with previous (1-6 years) myocardial infarction underwent two sequential 15-day treatments, respectively, on heparin and on placebo (saline solution), preceded and separated by 10-day wash-out periods. Heparin (as calcium heparin, 12,500 IU in 0.5 ml) and saline (0.5 ml) were subcutaneously administered once a day at 8 a.m. Blood samples for fibrinolysis studies were withdrawn on the first and 15th day of each period immediately before and 4 h after heparin or saline administration before and after 10 min venous occlusion (VO) respectively. Four hours after the first heparin administration tissue plasminogen activator antigen (t-PA ag) levels significantly increased with respect to saline administration (p < 0.01 and p < 0.05, respectively). After 15-day heparin treatment a decrease in euglobulin lysis time (p < 0.05) and an increase in t-PA activity (act) (p < 0.05) and in t-PA ag (p < 0.01) in comparison with placebo were observed before VO. No statistically significant changes in plasminogen activator inhibitor-1 (PAI-1) levels were found. The variations of fibrinolytic system activity induced by heparin treatment were more marked when evaluated after VO. These results indicate that medium-term low-dose heparin treatment increases t-PA ag formation and/or release with consequent t-PA act increase.

Acute reduction of TxA2 platelet binding sites after in vivo administration of a TxA2 receptor inhibitor

1. Picotamide has been shown to interfere competitively with the thromboxane A2 (TxA2) platelet receptor. In the present study the effect of in vivo administration of picotamide on TxA2 human platelet receptors was investigated in 10 healthy subjects. 2. Picotamide (300 mg x 3 daily) or placebo were administered in a double-blind, cross-over, placebo controlled study, each treatment lasting 1 week with a 2 week interval period. TxA2 receptors were investigated by a direct radioligand binding assay method employing [125I]-PTA-OH as labelled ligand. Platelet studies were performed on the first day of treatment immediately before and 2, 4 and 8 h after the ingestion of the drug. The effects of chronic administration were assessed on the seventh day. 3. Two and 4 h after the administration of picotamide 300 mg orally platelet TxA2 receptors were significantly reduced from 1366 +/- 237 to 957 +/- 221 (P less than 0.05) and 753 +/- 119 receptors/platelet (mean +/- s.d.) (P less than 0.03). After 8 h platelet receptor population was restored (1362 +/- 324, NS). The same pattern was observed after 7 days of treatment. Thus picotamide seems to induce a short lasting down regulation of platelet TxA2 receptors.

Platelet thromboxane A2 receptors in type I diabetes

1. Human platelet thromboxane A2 receptor expression on the membrane surface is possibly dynamically regulated by changes either in the ligand concentration or in membrane fluidity. An increased thromboxane A2 production and a decreased membrane fluidity has been reported in diabetic patients. 2. In the present study the binding characteristics of platelet thromboxane A2 receptors have been investigated in nine diabetic patients (type I) and in 15 healthy control subjects by a radioligand-binding method using 9,11-dimethylmethane-11,12-methane-16-[3-125I-4-hydroxyphenyl]-13, 14- dihydro-13-aza-15-tetranor-thromboxane A2 as the radiolabelled ligand. 3. The maximum concentration of binding sites was 163 (SD 35) fmol/10(8) platelets (n = 15) with 987 (SD 209) receptors/platelet in controls, whereas in diabetic patients the maximum concentration of binding sites was 74.2 (SD 28) fmol/10(8) (n = 9) with 447 (SD 172) receptors/platelet (P less than 0.001). The dissociation constants were 18 (SD 4) nmol/l and 21 (SD 6) nmol/l (not significant) in control subjects and in diabetic patients, respectively. Glycated haemoglobin, which is reported to reduce membrane fluidity, was found to be negatively correlated (r = 0.60, P less than 0.05) with thromboxane A2 receptor number in the diabetic patient group. On the contrary, a positive linear correlation between the equilibrium dissociation constant and glycated haemoglobin was found in diabetic patients (r = 0.75, P less than 0.01).