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Biomedical subjects

A Colella

Publications and source records attributed to A Colella.

At least 19 recordsLinked to original sources
PubMed2006

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.

Adult↗
PubMed2006

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''.

Cardiac Pacing, Artificial↗
PubMed2006

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.

Arrhythmias, Cardiac↗
PubMed2005

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.

Aged↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Aged↗
PubMed2001

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.

Aged↗
PubMed2001

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.

Aged↗
PubMed2001

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.

Aged↗
PubMed2000

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.

Aged↗
PubMed2000

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.

Aged↗
PubMed2000

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.

Atrial Appendage↗
PubMed2000

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.

Acetylcholinesterase↗
PubMed1999

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.

Adult↗
PubMed1998

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.

2,3-Diphosphoglycerate↗