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Biomedical subjects

Mauro Biffi

Publications and source records attributed to Mauro Biffi.

50 records · Page 3Linked to original sources
PubMed2003

Abnormal cardiac innervation in patients with idiopathic ventricular fibrillation.

Idiopathic ventricular fibrillation (VF) is diagnosed in up to nearly 10% of survivors of out-of-hospital cardiac arrest. The arrhythmogenic substrate is unknown. This study examined the role of cardiac innervation as a possible contributor to this arrhythmia. Eight patients with idiopathic VF were compared with eight normal subjects (controls) by [123] I metaiodobenzylguanidine SPECT (MIBG), measuring peak uptake, late uptake, and clearance of the nuclear tracer. The left ventricle was divided in 13 segments in the bull's-eye target plot. Peak and late MIBG uptake was increased in the anterolateral segments (2,3,7,8) compared to the inferoposterior and septal segments, in controls and in patients. No difference was observed between controls and patients in the inferoposterior and septal segments. In contrast, a significantly higher MIBG uptake was observed in patients compared to controls in the anterolateral segments (94 +/- 4% vs 81 +/- 11%, P < 0.03 for peak uptake; 94 +/- 5% vs 79 +/- 12%, P < 0.01 for late uptake). No difference was observed in MIBG clearance in any segment in either study group. Cardiac sympathetic innervation is highly heterogeneous, though predominant in anterolateral segments in normal subjects. Patients with idiopathic VF exhibit the same distribution, though have a significantly greater density of sympathetic terminals in the anterolateral segments than controls, which may promote ventricular arrhythmias.

3-Iodobenzylguanidine↗
PubMed2003

Evaluation of a dual chamber implantable cardioverter defibrillator for the treatment of atrial and ventricular arrhythmias.

Eighty-nine patients with a documented history of atrial tachyarrhythmias or fibrillation (AF) received a cardioverter defibrillator designed to selectively differentiate and treat atrial and ventricular arrhythmias. Twenty-two patients received a coronary sinus lead and, therefore, could use a separate shock vector for selective treatment of atrial tachyarrhythmias/AF. The device is designed to treat tachyarrhythmias with antitachycardia pacing (ATP) and/or shock therapy using an atrial and/or a ventricular shock vector. Patients underwent induction and shock termination of atrial or dual tachyarrhythmias (AF/VF) to verify proper device function and to measure the arrhythmia detection time with enhancements and preventive algorithms programmed On and Off, respectively. Detection time for 329 VF inductions was 2.41 +/- 0.64 seconds with enhancements On and 2.29 +/- 0.47 with enhancements Off (NS). At implant or predischarge, 283 AF and/or AF/VF (121 atrial and 162 atrial/ventricular fibrillation) were induced. Shock conversion efficacy was 89.8% with AF conversion energies ranging from 0.9 to 27 J. Thirteen of the 23 patients had atrial shock conversions using the separate shock vector with an average conversion energy of 1.9 +/- 1.4 J. (range 0.5-5 J). During follow-up the efficacy of ATP on atrial tachyarrhythmias was 59% and the efficacy of delivered shocks on AF was 85%. This new dual chamber cardioverter defibrillator appropriately detected and classified atrial arrhythmias, and shock therapy for AF was highly effective. The detection algorithm differentiated atrial tachyarrhythmia/AF and did not delay VF detection. The separate shock vector converted induced AF with energies ranging from 0.6 to 5 J.

Atrial Fibrillation↗
PubMed2003

Rhythm discrimination by rate branch and QRS morphology in dual chamber implantable cardioverter defibrillators.

Morphology Discrimination is a discriminator based on QRS morphology analysis that has been recently implemented in dual chamber implantable cardioverter defibrillators (ICDs). Detected events are initially classified according to median atrial and ventricular rates (Rate Branch). Then, a series of discriminators (Morphology Discrimination, Stability, Sudden Onset) analyze the rhythm according to specific criteria and the number of discriminators required for VT diagnosis (i.e., requiring "any" or "all" of the specific discriminators to indicate VT). The discriminating accuracy of the algorithm was evaluated in 645 detections recorded during the follow-up of 25 patients. The overall specificity for 397 supraventricular arrhythmias was 73.5% (292/397) with the tachycardia diagnosis criteria set to "any" and 90.9% (361/397) with the tachycardia diagnosis criteria set to "all." Sensitivity for VT was 100% and 98.7% (231/234) with the tachycardia diagnosis criteria set to "any" and "all," respectively. With the tachycardia diagnosis criteria set to "any," specificity for atrial fibrillation was 88.6%, for atrial flutter 40.3%, for atrial tachycardia 0%, and for sinus tachycardia 97.0%. With the tachycardia diagnosis criteria set to "all," specificity for atrial fibrillation was 92.40%, for atrial flutter 93.5%, for atrial tachycardia 54.7%, and for sinus tachycardia 99.0%. The contribution of Morphology Discrimination was crucial to improve the specificity of the Rate Branch algorithm. The implementation of Morphology Discrimination in a dual chamber ICD with Rate Branch rhythm classification allows the attainment of high specificity and high sensitivity for ventricular tachyarrhythmias.

Aged↗
PubMed2003

Late improvement in ventricular performance following internal cardioversion for persistent atrial fibrillation: an argument in support of concealed cardiomyopathy.

The aim of the study was to evaluate the time course of atrial and ventricular function improvement following internal atrial cardioversion in patients with structural heart disease. Twenty-nine patients with chronic persistent atrial fibrillation (AF) and underlying structural heart disease were followed by serial echocardiograms performed at 1 and 6 hours, 1 day, 1, 2, and 3 weeks, and 1, 2, 3, and 6 months after successful cardioversion. Sinus rhythm was maintained at 6 months in 24 patients. Following cardioversion the time course of left atrial mechanical function (peak A wave, percent A wave filling) differed from that of left ventricular ejection fraction: peak A wave values (cm/s) increased significantly at 1 week (51 +/- 23 vs 35 +/- 15 at 1 hour, P < 0.05), percent A wave filling (%) increased significantly at 2 weeks (34 +/- 12 vs 22 +/- 9 at 1 hour, P < 0.05), whereas left ventricular ejection fraction (%) increased later (at 1 month 60 +/- 14 vs 55 +/- 14 at baseline, P < 0.05 and at 2 months 60 +/- 14 vs 56 +/- 14 at 1 hour, P < 0.05). In conclusion, restoration of sinus rhythm results in an improvement in left ventricular ejection fraction during follow-up, even in patients with structural heart disease without fast ventricular rates at baseline. The dissociation between the time course of atrial and ventricular function improvement suggests that the latter was partly due to regression of a concealed form of cardiomyopathy and/or of a ventricular dysfunction due to chronic AF.

Analysis of Variance↗
PubMed2003

Rate control in atrial fibrillation: choice of treatment and assessment of efficacy.

The clinical relevance and high social costs of atrial fibrillation have boosted interest in rate control as a cost-effective alternative to long-term maintenance of sinus rhythm (i.e. rhythm control). Prospective studies show that rate control (coupled with thromboembolic prophylaxis) is a valuable treatment option for all forms of atrial fibrillation. The rationale for rate control is that high ventricular rates, frequently found in atrial fibrillation, lead to haemodynamic impairment, consisting of a variable combination of loss of atrial kick, irregularity in ventricular response and inappropriately rapid ventricular rate, depending on the type of underlying heart disease. Long-term persistence of tachycardia at a high ventricular rate can lead to various degrees of ventricular dysfunction and even to tachycardiomyopathy-related heart failure. Identification of this reversible and often concealed form of left ventricular dysfunction can permit effective management by rate (or rhythm) control. Although acute rate control (to reduce ventricular rate within hours) is still often based on digoxin administration, for patients without left ventricular dysfunction, calcium channel antagonists or beta-adrenoceptor antagonists (beta-blockers) are generally more appropriate and effective. In chronic atrial fibrillation, long-term rate control (to reduce morbidity/mortality and improve quality of life) must be adapted to patients' individual characteristics to grant control during daily activities, including exercise. According to current guidelines, the clinical target of rate control should be a ventricular rate below 80-90 bpm at rest. However, in many patients, assessment of the appropriateness of different drugs should include exercise testing and 24h-Holter monitoring, for which specific guidelines are needed. In practice, rate control is considered a valid alternative to rhythm control. Recent prospective trials (e.g. the Pharmacological Intervention in Atrial Fibrillation [PIAF] and the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] trials) have shown that in selected patients, rate control provides similar benefits, more economically, in terms of quality of life and long-term mortality. The choice of a rate control medication (digoxin, beta-blockers, calcium channel antagonists or possibly amiodarone) or a non-pharmacological approach (mainly atrioventricular node ablation coupled with pacing) must currently be based on clinical assessment, which includes assessing the presence of underlying heart disease and haemodynamic impairment. Definite guidelines are required for each different subset of patients. Rate control is particularly tricky in patients with heart failure, for whom non-pharmacological options can also be considered. The preferred pharmacological options are beta-blockers for stabilised heart failure and digoxin for unstabilised forms.

Animals↗
PubMed2003

Increased expression of alpha(1,3)-fucosyltransferase-VII and P-selectin binding of synovial fluid T cells in juvenile idiopathic arthritis.

OBJECTIVE: The mechanisms controlling the recruitment of T helper type 1 (Th1) cells to the inflamed synovium are not fully understood. Here, we focus on alpha(1,3)-fucosyltransferase-VII (FucT-VII), an enzyme responsible for the generation of functional P- and E-selectin ligands that is upregulated in Th1 cells. METHODS: Expression of transcripts encoding FucT-VII, interferon-gamma (IFN-gamma), and interleukin 12Rbeta2 (IL-12Rbeta2) were analyzed in T cells purified from synovial fluid (SF) and from peripheral blood (PB) of children with juvenile idiopathic arthritis (JIA) using kinetic reverse transcriptase polymerase chain reaction analysis. Binding of SF and PB T cells to P-selectin was determined by flow cytometry using a soluble P-selectin/IgG1 fusion molecule. Recruitment of T cells to synovial tissue in vivo was studied by analyzing the migration of FucT-VII transfected Jurkat T cells into human rheumatoid synovial tissue grafted into SCID mice. RESULTS: In patients with JIA, the mRNA levels of FucT-VII, as well as of IFN-gamma and IL-12Rbeta2, were up-regulated in SF T cells compared to paired PB T cells. A higher expression of FucT-VII mRNA in SF T cells was associated with increased binding of T cells to P-selectin. Moreover, FucT-VII expression and increased P-selectin binding capacity of T cells were associated with a polyarticular course of oligoarticular JIA. Expression of FucT-VII in Jurkat T cells resulted in an increased accumulation of these cells in human rheumatoid synovial tissue grafted into SCID mice. CONCLUSION: Our data indicate an important role of FucT-VII in the enhanced homing of T cells to the inflamed synovium.

Adolescent↗
PubMed2002

A randomised cross-over study on the haemodynamic effects of oral dofetilide compared with oral sotalol in patients with ischaemic heart disease and sustained ventricular tachycardia.

OBJECTIVE: To assess the haemodynamic effects of short-term treatment with dofetilide in comparison with sotalol in patients with ischaemic heart disease. METHODS: Twelve patients with ischaemic heart disease and sustained ventricular tachycardia were treated with dofetilide [500 microg twice daily (b.i.d.)] or sotalol (160 mg b.i.d., randomised sequence separated by wash-out period) for 3-5 days. Right-heart catheterisation was performed at baseline and at the end of each short-term treatment phase. RESULTS: The main findings were a significant reduction in heart rate, mean systemic pressure and cardiac index (-13%) during treatment with sotalol. Conversely, cardiac index increased significantly during dofetilide (mean percentage change 11%) with no effect on heart rate and systemic blood pressure. CONCLUSIONS: Oral dofetilide exerts favourable haemodynamic effects in comparison with D,L-sotalol following short-term oral treatment. In view of these observations, the use of dofetilide may be proposed also in patients with ventricular tachyarrhythmias associated with impaired left-ventricular function. Whether the haemodynamic differences between dofetilide and D,L-sotalol are the basis for differences in tolerability remains to be evaluated.

Administration, Oral↗
PubMed2002

Combined use of morphology discrimination, sudden onset, and stability as discriminating algorithms in single chamber cardioverter defibrillators.

Morphology Discrimination (MD) is a rhythm discriminator based on QRS morphology analysis that can be combined with other discriminators like Stability, with or without Sinus Interval History (SIH) and Sudden Onset. Thirty-five patients implanted with a St. Jude Medical single chamber ICD were evaluated during exercise testing, during induced AF, and during follow-up for 14 +/- 5 months. At exercise testing (60 episodes detected) MD had a specificity (SP) of 96.7% and Sudden Onset a SP of 91.7%; during induced AF (25 episodes) both MD and Stability had a SP of 96.0%. The diagnostic performance on spontaneous arrhythmias was as follows: for ventricular tachycardia (126 episodes) a sensitivity (SE) of 94.4% for MD, 92.1% for Sudden Onset, 89.7% for Stability without SIH and 79.4% for Stability + SIH; for sinus tachycardia (44 episodes) a SP of 86.4% for MD, 97.7% for Sudden Onset, 2.3% for Stability and of 95.5% for Stability + SIH. For AF (165 cases) a SP of 67.9% for MD, 69.1% for Stability and 90.3% for Stability + SIH, 44.8% for Sudden Onset. Use of MD alone provided a SE of 94.4% and a SP of 71.4% for spontaneous arrhythmias and combined use of the discriminators in a "2 of 3" diagnostic logic implied a SP of 90.9% with maintenance of 96.0% of SE. In single chamber ICDs a wide range of SE/SP ratios may be obtained by use of multiple discriminators, but use of the algorithm in a 2 of 3 diagnostic logic may achieve a SP of 90.9% and a SE of 96.0%.

Algorithms↗
PubMed2002

Atrial signal analysis and defibrillation threshold assessment in chronic persistent and reinduced atrial fibrillation.

INTRODUCTION: Induced versus spontaneous atrial fibrillation (AF) is of interest for assessing atrial defibrillation threshold reproducibility. METHODS AND RESULTS: Twenty-one patients with chronic AF underwent internal cardioversion with assessment of atrial defibrillation threshold at baseline and at reinduced AF. High right atrial (HRA) and coronary sinus (CS) bipolar recordings were analyzed to measure the mean local atrial period, its coefficient of variation, the 5th (P5) and 95th (P95) percentiles of atrial intervals, and the percentage of points lying at the baseline (number of occurrences), and to quantify AF organization. Atrial defibrillation threshold was comparable in baseline and reinduced AF in terms of leading-edge voltage and delivered energy. Baseline and reinduced AF were comparable with regard to overall signal parameters (both in HRA and CS) and the presence of an organized arrhythmia pattern. As for individual variables, P5 increased while P95 and coefficient of variation decreased in reinduced AF compared with spontaneous AF (statistical significance was achieved for all these parameters in HRA, but only for coefficient of variation and P95 in CS). CONCLUSION: Sustained AF reinduced after cardioversion of chronic AF is comparable with baseline AF in terms of atrial defibrillation threshold, atrial cycle length, and pattern of organization. Therefore, a clinical model based on reinduction of sustained AF after cardioversion is suitable for studying the effects of a series of interventions on atrial defibrillation threshold. However, because this model does not yield a form of AF with comparable indices of local refractoriness (e.g., P5), it is not recommended when analyzing local electrophysiologic properties.

Adult↗
PubMed2002

Transvenous internal cardioversion for atrial fibrillation: a randomized comparison between catheters with different coil length.

OBJECTIVES: The aim of this study was to evaluate the effects of 2 different right atrial electrode coil lengths on energy and voltage requirements for transvenous atrial cardioversion. METHODS: Twenty-six patients (mean age 61 +/- 11 years) with chronic persistent atrial fibrillation (AF) (mean duration 11 +/- 10 months) underwent transvenous cardioversion. A 6F catheter with a 5.5-cm coil was positioned in the coronary sinus. Another catheter with either a 5.5-cm or an 8-cm coil was positioned along the lateral wall of the right atrium, according to a randomized allocation. R wave-synchronized biphasic shocks were delivered according to a step-up protocol. After cardioversion of baseline AF, AF was reinduced, the right atrial catheter was substituted, and cardioversion was repeated with the alternative right atrial coil. RESULTS: Successful cardioversion was obtained in all of the patients. Leading edge voltage of effective shocks was significantly lower when catheters with an 8-cm coil in right atrium were used compared with the alternative 5-cm coil catheters (301 +/- 80 volts vs 340 +/- 78 volts, P <.001), and delivered energy (6.75 +/- 4.25 joules vs 7.86 +/- 4.29 joules, P =.043) and shock impedance (60 +/- 9 ohm vs 66 +/- 10 ohm, P <.001) were lower. Moreover, shock-induced discomfort, evaluated by assessment of pain score, was reduced (3.69 +/- 1.09 vs 4.12 +/- 0.99, P =.035). CONCLUSIONS: The use of a longer right atrial coil results in lower shock impedance, lower energy and voltage requirements, and lower discomfort during transvenous atrial cardioversion. The results of the current study are of value either for transvenous internal cardioversion of chronic persistent AF or for implantable atrial defibrillators.

Adult↗
PubMed2002

Current clinical perspectives on implantable devices for atrial defibrillation.

The role of devices that deliver shock therapy for atrial fibrillation is still debated. Following technical improvements in catheter-based atrial defibrillation, implantable devices have become available either in the form of stand-alone atrial defibrillators or in the form of dual defibrillators. Although preliminary results do not support their use as a single, unique treatment for atrial fibrillation patients, in combination with drugs, pacing or other treatments such as ablation, atrial defibrillators should help appropriately selected groups of patients.

Atrial Fibrillation↗
PubMed2002

Oral loading with propafenone for conversion of recent-onset atrial fibrillation: a review on in-hospital treatment.

Atrial fibrillation (AF) is a very common arrhythmia. In order to treat acute AF rapidly, effective drug regimens are required. Propafenone is a class IC antiarrhythmic agent that is suitable for oral loading as it reaches peak plasma concentrations within 2 to 4 hours of administration. The use of propafenone loading in patients with AF must be based on appropriate patient selection in view of the negative inotropic effect and the potential proarrhythmic effects of the drug. A series of controlled trials in patients with recent-onset AF without heart failure who were hospitalised with enforced bed rest has shown that orally loaded propafenone (450 to 600 mg as single dose) exerts a relatively quick effect (within 3 to 4 hours) and a high rate of efficacy (72 to 78% within 8 hours). A potentially harmful effect of class IC agents is the risk of transforming AF into atrial flutter (3.5 to 5% of patients). However, atrial flutter with 1 : 1 atrioventricular response was observed in only two of 709 patients receiving propafenone (0.3% incidence). Nevertheless, the potential negative inotropic effect of propafenone demands careful patient selection, with systematic exclusion of patients with left ventricular dysfunction or congestive heart failure. Oral loading with propafenone can be considered as an episodic treatment in patients with AF recurrences, as has been proposed for other drugs in the past. However, the safety of oral loading with propafenone as an outpatient treatment in appropriately selected patients has to be assessed by appropriately designed prospective studies.

Administration, Oral↗