Microbiology Culture Results and Antibiotic Prescribing in Pediatric Patients With Lymphadenitis

BACKGROUND

Bacterial lymphadenitis is a common reason for antibiotic treatment and hospitalization in children. The literature available addressing the bacterial etiology of lymphadenitis recommends the use of narrow-spectrum agents to cover common pathogens. We suspect that patients at our institution receive unnecessarily broad-spectrum antimicrobial agents. The primary objective of this study was to characterize the microbiology and antibiotic use in lymphadenitis patients.

METHODS

Retrospective review of children admitted over a 10-year period with an International Classification of Diseases Ninth or Tenth Edition code for lymphadenitis. Patients were included if they were <18 years old, admitted to the inpatient ward, and had intraoperative lymph node cultures collected.

RESULTS

A total of 131 patients admitted with lymphadenitis had lymph node cultures collected and were included. Seventy-two (72/131; 55%) patients had positive lymph node culture results with pathogenic bacteria. The predominant pathogens were Staphylococcus aureus (56/72; 77.8%) and Streptococcus pyogenes (10/72; 13.9%). The most common inpatient empirical regimen was ampicillin-sulbactam. Of the 72 patients with typical pathogens identified, 80.6% were sensitive to a first-generation cephalosporin, whereas 86.1% were sensitive to a β-lactam/β-lactamase inhibitor.

CONCLUSION

Patients presenting to our institution with acute bacterial lymphadenitis were predominantly found to have methicillin-susceptible S. aureus lymphadenitis that could be empirically treated with cefazolin. At our institution, there is little advantage to the most commonly used broad-spectrum agent, ampicillin-sulbactam.

P1464A question of gender equality. Sex-related differences in survival after primary prevention implantable cardioverter-defibrillator implantation for dilated cardiomyopathy An analysis from POLKARD

OnBehalf

POLKARD Polish ICD Registry

Background

The protective effects of implantable cardioverter defibrillators (ICDs) in the primary prevention of sudden cardiac death of patients presenting with left ventricular (LV) systolic dysfunction are unequivocal. Nevertheless, female underrepresentation has been a consistent finding in all randomized controlled primary prevention ICD trials. Surprisingly, there is a vast body of literature on female primary prevention ICD patients exhibit a lower overall mortality.

Purpose

Therefore, we analyzed data from a large, nationwide POLKARD registry to evaluate the effect of sex on survival after primary prevention cardioverter-defibrillator implantation for dilated cardiomyopathy.

Methods

All patients enrolled in the Polish ICD Registry from 2008 to 2014 were identified. Patients were included in the study if they were designated as receiving an ICD for primary prevention of SCD after documented non-ischeamic cardiomyopathy. Kaplan-Meier survival analysis was used to assess all-cause mortality.

Results

Of the 964 ICD recipients, 241 (25%) were women (mean age of 64± 0,45 years). During a mean follow-up of 5,53 ± 2,48 years 32% of women and 42% of men died. Kaplan-Meier curve depicted a significantly lower mortality for women than for men (p = 0,05). The median survival time was 6,73 years (55 deaths per 1000 person-years) versus 6,37 years (78 deaths per 1000 person-years) for women and men, respectively.

Conclusions

In agreement with previous studies, our data indicate that primary prevention implantation rates for dilated cardiomyopathy are lower in women. However, the reasons are not entirely understood.

P1463Regional variation in survival rates among primary prevention implantable cardioverter-defibrillator recipients in Eastern and Northern Europe POLKARD Polish ICD Registry perspective

Funding Acknowledgements

None.

OnBehalf

POLKARD Polish ICD Registry

Objective

The findings of Danish Study to assess the efficiency of ICD in patients with non ischemic heart failure has recently raised questions about the current strategy of ICD implantation for the primary prevention of sudden cardiac death. POLKARD - Polish ICD Registry is a prospective, non-randomised, central registry of patients who are referred for an implantation of an ICD in Poland. The Registry contains prospectively collected follow-up data including mortality.

Purpose

To compare survival rates between Polish and Danish ‘real-world’ non-ischemic primary prevention cohorts.

Methods

Retrospective analysis of clinical characteristics and long-term follow-up of patients referred for primary prophylactic implantable cardioverter defibrillator (ICD) implantation in Poland between April 2008 and November 2014 was performed. The primary outcome of the trial was all-cause mortality. Results: The polish study cohort was large (964) as compared to Danish population randomized to receive ICD therapy (556). The median follow-up time in DANISH Study and Polish ICD Registry was 67,6 and 77 months, respectively. Compared with patients enrolled in the DANISH Study, patients in the Polish ICD Registry were age-similar. However, the polish study population was male-dominated. What is more, male gender was identified as a risk factor for long-term mortality in polish study population (p = 0.005). In the matched cohorts, there was difference in survival between DANISH Study and Polish ICD Registry patients (all-cause mortality rates: 21,6% - 44 events per 1000 person-years and 39,3% - 72 events per 1000 person-years, respectively).

Conclusions

Our findings imply that survival among patients who receive a primary prevention ICD for non-ischemic cardiomyopathy in clinical practice in Central Europe is different from Northern Europe.

P2878Higher all-cause mortality in patients with implanted dual-chamber cardioverter-defibrillators for secondary prevention: an analysis from the Polish ICD Registry

Background

In the Polish ICD Registry population secondary prevention recipients account for over 27%. Despite the evolution of indications for secondary prevention implantable cardioverter defibrillators (ICDs), recommendations regarding the use of ICDs for secondary prevention of sudden cardiac death (SCD) rely on information from a small number of randomized controlled trials that were performed decades ago, with mixed results. Moreover, research on the outcomes after implantations for secondary prevention of ICDs is limited. While dual-chamber devices offer theoretical advantage over single-chamber devices, dual-chamber ICDs (DC-ICDs) were announced not superior to single-chamber (SC-ICDs) in some research.

Purpose

Therefore, the aim of the study was to evaluate the all-cause mortality among patients from the Polish ICD Registry receiving either a single- or a dual-chamber device for secondary prevention in contemporary clinical practice.

Methods

All patients enrolled in the Polish ICD Registry from 1995 to 2016 were identified. Patients were included in the study if they were designated as receiving an ICD for secondary prevention of SCD after documented tachycardic arrest, sustained ventricular tachycardia (VT), or syncope. Kaplan-Meier survival analysis was used to assess all-cause mortality.

Results

In the study population of 3596 ICD recipients (mean age 69±12 years, 81% male, SC-ICD 61%, DC-ICD 39%), during mean follow-up of 79±43 months all-cause mortality rate was higher in the dual-chamber group than in the single chamber group, with a significant difference between the two groups as depicted in Kaplan-Meier curve (p<0,05). The median survival time was 98 months versus 110 months for SC and DC-ICD, respectively.

Conclusions

This study is the first to describe the characteristics of a national cohort of patients receiving a secondary prevention ICD in such a long follow-up period in contemporary practice. Implantation of a dual-chamber ICD was associated with higher all-cause mortality compared with single chamber devices.

Fast polarization mechanisms in the uniaxial tungsten-bronze relaxor strontium barium niobate SBN-81

The high-frequency dielectric response of the uniaxial strontium barium niobate crystals with 81% of Sr has been studied from 1 kHz to 30 THz along the polar c axis by means of several techniques (far infrared, time domain terahertz, high-frequency and low-frequency dielectric spectroscopies) in a wide temperature interval 20–600 K. Relaxor properties were observed in the complex dielectric response and four main excitations were ascertained below the phonon frequencies. These fast polarization mechanisms take place at THz, GHz and MHz ranges and show different temperature evolution. The central mode excitation in the THz range, related to anharmonic dynamics of cations, slightly softens from high temperatures and then hardens below T ~ 400 K. Below the phase transition (at T ~ 330 K) an additional microwave excitation appears near 10 GHz related to micro domain wall oscillations. The strongest relaxation appears in the GHz range and slows down on cooling according to the Arrhenius law. Finally, another relaxation, present in the MHz range at high temperatures, also slows down on cooling at least to the kHz range. These two relaxations are due to polar fluctuations and nanodomains dynamics. Altogether, the four excitations explain the dielectric permittivity maximum in the kHz range.

Spectroscopic studies of the ferroelectric and magnetic phase transitions in multiferroic Sr1-xBaxMnO3

Dielectric response of perovskite Sr1-xBaxMnO3 (x = 0.43 and 0.45) ceramics was investigated using microwave, THz and infrared spectroscopic techniques in order to study the ferroelectric and antiferromagnetic phase transitions with critical temperatures TC ≈ 350 K and TN ≈ 200 K, respectively. The two lowest-frequency polar phonons are overdamped above TN and they exhibit pronounced softening on heating towards TC. Nevertheless, permittivity ε' in the THz range shows only a small anomaly at TC because the phonon contribution to ε' is rather small. The phonons are coupled with a central mode which provides the main contribution to the dielectric anomaly at TC. Thus, the ferroelectric phase transition has characteristics of a crossover from displacive to order-disorder type. At the same time, the intrinsic THz central peak is partially screened by conductivity and related Maxwell-Wagner relaxation, which dominates the microwave and lower-frequency spectra. Below TN, the ferroelectric distortion markedly decreases, which has an influence on the frequencies of both the central and soft modes. Therefore, ε' in the THz range increases at TN on cooling. In spite of the strong spin-phonon coupling near TN, surprisingly no magnetodielectric effect was observed in the THz spectra upon applying magnetic field of up to 7 T, which is in contradiction with the theoretically expected huge magnetoelectric coupling. We explain this fact as due to the insensitivity of TN to magnetic field.

Dynamics of nanoscale polarization fluctuations in a uniaxial relaxor

We have studied neutron diffuse scattering in a Sr(0.61)Ba(0.39)Nb(2)O(6) single crystal by neutron backscattering at sub-μeV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells.

An x-ray scattering study of Sn2P2S6: absence of incommensurate phase up to 1 GPa

The ferroelectric phase transition in a semiconductor Sn(2)P(2)S(6) single crystal has been studied by means of high-resolution synchrotron x-ray diffraction in the pressure-temperature range where an incommensurate modulated phase has been anticipated for many years. In contrast with the predictions, the present measurements reveal only a direct ferroelectric-paraelectric phase transition close to T = 100 K, p = 1.1 GPa. In the vicinity of this phase transition, a characteristic critical diffuse scattering was observed, but no satellite peaks could be resolved there. It is concluded that the earlier hypothesis about the presence of an incommensurate phase and associated Lifshitz point in the temperature-pressure phase diagram of Sn(2)P(2)S(6) is incorrect.

Broad-band conductivity and dielectric spectroscopy of composites of multiwalled carbon nanotubes and poly(ethylene terephthalate) around their low percolation threshold

Composites of multiwalled carbon nanotubes with poly(ethylene terephthalate) (PET-MWCNT) with up to 3 vol% MWCNTs were prepared and characterized by broad-band AC conductivity and dielectric spectroscopy up to the infrared range using several techniques. A very low electrical percolation threshold of 0.07 vol% MWCNTs was revealed from the low-frequency conductivity plateau as well as from DC conductivity, whose values show the same critical power dependence on MWCNT concentration with the exponent t = 4.3. Above the plateau, the AC conductivity increases with frequency up to the THz range, where it becomes overlapped with the absorption of vibrational modes. The temperature dependence down to ~5 K has shown semiconductor behaviour with a concentration-independent but weakly temperature-dependent small activation energy of ~3 meV. The behaviour is compatible with the previously suggested fluctuation-induced tunnelling conductivity model through a thin (~1 nm) polymer contact layer among the adjacent MWCNTs within percolated clusters. At higher frequencies, deviations from the simple universal conductivity behaviour are observed, indicating some distribution of energy barriers for an electron hopping mechanism.

The temperature dependence of the phononic band gap of NaI

The position and size of the energy gap in the phonon density of states of NaI single crystal have been investigated by inelastic neutron scattering in a wide range of temperatures from 10 to 700 K. The results reveal a pronounced temperature effect which effectively leads to closure of the phonon gap at temperatures in the range of 700-800 K. The results are discussed in the context of studies of possible intrinsic localized modes in the phonon gap of alkali halides.

Demographic characteristics and estimated prevalence of Fontan-associated plastic bronchitis

Plastic bronchitis (PB) is a poorly understood disease that can complicate any underlying pulmonary disease. However, it appears to most often occur in patients with surgically palliated congenital heart disease, particularly after the Fontan procedure. Few data exist about the prevalence and etiology of PB in this population. In an effort to establish data about prevalence, we conducted a retrospective study of an existing Fontan surgery database (n = 654) comprised of data, including sex, age at date of surgery, alive/dead status, New York Heart Association classification at last follow-up, right-ventricular end-diastolic pressure and pulmonary artery pressure before Fontan surgery, and the presence of a Fontan fenestration. An initial medical record review of 173 patients in the database who were followed at the University of Michigan identified seven patients with PB resulting in an estimated prevalence of 4 %. Subsequently, 14 % of 211 surveyed patients reported that they presently expectorate mucus or fibrin plugs (casts). Demographic and clinical variables did not differ between patients with or without possible PB. Collectively, these findings suggest that Fontan patients presently with PB may range from 4 to 14 %, indicating potential under-diagnosis of the disease. There were no remarkable physical or hemodynamic indicators that differentiated patients with or without possible PB. These data also highlight the need for more elaborate, prospective studies to improve our understanding of PB pathogenesis so that more definitive diagnostic criteria for this devastating disease can be established and its prevalence more accurately determined.

Dielectric, magnetic and structural properties of novel multiferroic Eu(0.5)Ba(0.5)TiO(3) ceramics

Dielectric properties of Eu(0.5)Ba(0.5)TiO(3) ceramics were investigated between 10 and 300 K in the frequency range of 1 MHz-100 THz. Permittivity exhibits a strong peak near the ferroelectric phase transition at 215 K. This is mainly due to softening of the lowest frequency polar phonon revealed in THz and infrared spectra. Dielectric relaxation was observed also below the ferroelectric soft mode frequency in the whole investigated temperature region, but it is probably caused by some defects such as Eu(3 + ) cations or oxygen vacancies. This implies that the ferroelectric phase transition has predominantly a displacive character. Raman scattering spectra revealed a lowering of crystal symmetry in the ferroelectric phase and XRD analysis indicated orthorhombic A2mm symmetry below 215 K. The magnetic measurements performed at various frequencies in the field cooled and field heating regime after cooling in zero magnetic fields excluded spin glass behavior and proved an antiferromagnetic order below 1.9 K in Eu(0.5)Ba(0.5)TiO(3).

Bulk dielectric and magnetic properties of PFW-PZT ceramics: absence of magnetically switched-off polarization

We investigated ceramics samples of solid solutions of [PbFe(2/3)W(1/3)O(3)](x)-[PbZr(0.53)Ti(0.47)O(3)](1 - x) (PFW(x)-PZT(1 - x), x = 0.2 and 0.3) by means of broad-band dielectric spectroscopy, differential scanning calorimetry and SQUID magnetometry. We did not confirm the observations of Kumar et al (2009 J. Phys.: Condens. Matter 21 382204), who reported on reversible suppression of ferroelectric polarization in polycrystalline PFW(x)-PZT(1 - x) thin films for magnetic fields above 0.5 T. We did not observe any change of ferroelectric polarization with external magnetic fields up to 3.2 T. Pirc et al (2009 Phys. Rev. B 79 214114) developed a theory explaining the reported large magnetoelectric effect in PFW(x)-PZT(1 - x), taking into account relaxor magnetic and relaxor ferroelectric properties of the system. Our data revealed classical ferroelectric properties below 525 K and 485 K in samples with x = 0.2 and 0.3, respectively. Moreover, paramagnetic behavior was observed down to 4.5 K instead of previously reported relaxor magnetic behavior. It seems that the reported switching-off of ferroelectric polarization in PFW(x)-PZT(1 - x) thin films is not an intrinsic property, but probably an effect of electrodes, interlayers, grain boundaries or second phases presented in polycrystalline thin films.

Soft and central mode behaviour in PbMg(1/3)Nb(2/3)O(3) relaxor ferroelectric

The relaxor ferroelectric PbMg(1/3)Nb(2/3)O(3) (PMN) is investigated by means of dielectric and Fourier transform far infrared transmission spectroscopy in the frequency range from 10 kHz to 15 THz at temperatures between 20 and 900 K using mostly thin films on infrared transparent sapphire substrates. While the thin film relaxors display reduced dielectric permittivity at low frequencies, their high frequency lattice response is shown to be the same as for single-crystal/ceramic specimens. In contrast to the results of inelastic neutron scattering, the optic soft mode is found to be underdamped at all temperatures. On heating, the TO1 soft phonon follows the Cochran law with an extrapolated critical temperature of 670 K near to the Burns temperature. Above 450 K the soft mode frequency levels off near 50 cm(-1) and above the Burns temperature it slightly hardens. Central-mode-type dispersion assigned to the dynamics of polar nanoclusters appears below the Burns temperature at frequencies near to but below the soft mode and slows down and broadens dramatically on cooling, finally, below the freezing temperature of 200 K, giving rise to frequency independent losses from the microwave range down. A new explanation of the phonon 'waterfall' effect in inelastic neutron scattering spectra is proposed.

Shortening the second phase duration of biphasic shocks: effects of class III antiarrhythmic drugs on defibrillation efficacy in humans

INTRODUCTION

The specific waveform providing optimal defibrillation threshold (DFT) is unknown. We compared the defibrillation efficacy of biphasic pulses with second phases (P2) of 2 and 5 msec in a randomized prospective clinical study.

METHODS AND RESULTS

Intraoperative DFTs of 62 patients (age 54 +/- 13 years; ejection fraction 43% +/- 17%; amiodarone 47%, d,l-sotalol 13%) were determined in random order using a binary search protocol. Anodal shocks of 60% tilt first phases (P1) and P2 of 2 msec/5 msec were delivered from two 100-microF capacitors between the right ventricular electrode and the test housing of a Phylax 06/XM device. Mean DFT was significantly lower using the shorter P2 (9.5 +/- 4.5 J vs 11.3 +/- 5.2 J; P < 0.0001). According to subgroup analysis, the effect of changing P2 duration was only influenced by antiarrhythmic treatment. DFT decreased markedly using the shorter P2 in patients treated with amiodarone (10.7 +/- 4.9 J vs 13.4 +/- 5.6 J; P < 0.00001) or d,l-sotalol (6.1 +/- 3.3 J vs 9.1 +/- 4.6 J; P < 0.05). The difference in patients not treated with Class III drugs was found to be insignificant. Chronic amiodarone treatment increased DFT only when the longer P2 was used.

CONCLUSION

Biphasic shocks with shorter P2 should be used in patients undergoing Class III antiarrhythmic treatment.

The influence of short-term treatment with simvastatin on the inflammatory profile of patients with hypercholesterolaemia

BACKGROUND

Treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors can reduce cardiovascular mortality of patients with atherosclerosis. This effect is probably due not only to a decrease in concentration of cholesterol, but also to non-lipid-involving mechanisms elicited by the action of statin drugs.

OBJECTIVE

To investigate the influence of short-term therapy with simvastatin on markers of inflammation and oxidation processes in patients with hypercholesterolaemia.

DESIGN

We administered 20mg simvastatin daily for 12 weeks to 19 patients with hypercholesterolaemia (250-400 mg/dl). Peripheral blood samples for evaluation of plasma concentrations of thiobarbituric acid reactive substances (malonaldehyde), stable metabolites of nitric oxide (NOx) and interleukin 6 (11-6) were taken before and after the therapy.

RESULTS

Plasma levels of malonaldehyde decreased significantly (from 4.533+/-0.428 versus 3.690+/-0.310 micromol/l, P = 0.04) during the study period. Similarly, there was a significant decrease in the plasma concentrations of NOx (from 33.477+/-4.352 micromol/l versus 25.919+/-2.561 micromol/l, P = 0.02). There were significant positive correlations between concentrations of total cholesterol and NOx in plasma (r = 0.4397, P = 0.008) and of low-density lipoprotein and NOx (r = 0.3987, P = 0.02). The plasma level of interleukin 6 remained unchanged by the intervention (1.837+/-0.200 versus 1.820+/-0.169 pg/ml, P = 0.54).

CONCLUSIONS

Short-term therapy with simvastatin decreases the plasma concentrations of markers of peroxidation of lipids and of stable metabolites of nitric oxide in hypercholesterolaemic patients, but leaves levels of interleukin 6 unaffected.

The terminal portion of the T wave: a new electrocardiographic marker of risk of ventricular arrhythmias

Experimental studies have shown that transmural dispersion of repolarization (DoR), defined as the difference in action potential duration between mid-myocardial M-cells, epicardial, and endocardial cells is reflected in the duration of the terminal portion of the T wave (TpTe) on the surface ECG. Since DoR is an important factor associated with the propensity for reentrant arrhythmias, this study examined if TpTe may serve as a marker of risk of ventricular arrhythmias. Data from 18 patients with coronary artery disease and inducible sustained ventricular tachycardia (VT group) were compared with those of 16 survivors of myocardial infarction without inducible VT (control group). TpTe was automatically measured in each beat of 24-hour ECG recordings, and programmed ventricular stimulation was performed in the antiarrhythmic drug-free state. TpTe was expressed as the absolute interval in milliseconds, and relative to the duration of QTe (TpTe/QTe x 100%). TpTe duration was 74 +/- 14 ms in the VT group versus 63 +/- 16 ms in the control group (P < 0.004). The TpTe interval expressed as a percent of the QT interval was 21 +/- 4% in the VT group versus 17 +/- 3% in the control group (P = 0.02). In patients with coronary artery disease. TpTe was longer in patients with, versus without, inducible VT. The results of this study support the hypothesis that TpTe reflects transmural dispersion of repolarization.

Implantation and follow-up of ICD leads implanted in the right ventricular outflow tract

Unipolar ICD electrodes are routinely implanted at the right ventricular apex (RVA). However, inappropriate pacing/sensing parameters and/or high DFT may limit the appropriateness of the lead's implantation at the RVA. This study examined the effects on DFT of ICD leads implanted in the RVOT, attached to the high interventricular septum as an alternate location. DFT, defibrillation impedance, and sensing and pacing characteristics were measured at the time of implantation in 28 consecutive patients. Group A consisted of 12 patients in whom the ICD implantation criteria in the RVA were not satisfied, and whose lead was placed in the RVOT. Group B consisted of 16 patients with ICD electrodes implanted at the RVA. Mean DFT in group A was 11 +/- 4 J (4.5-20 J) versus 12 +/- 6 J (4-20 J) in the group B (P = 0.58). Defibrillation impedance was 81 +/- 9 omega (69-92 omega) in group A versus 77 +/- 15 omega) (46-93 omega) in group B (P = 0.43). R wave amplitude, slew rate, pacing threshold, and pacing impedance were comparable in both groups. In the perioperative period, the electrode needed to be repositioned in two patients from group A. There was no further dislodgment of RVOT defibrillation leads or other lead related complications during a follow-up of 23 +/- 9 months. The placement of ICD leads in the RVOT is an alternative to the RVA position. However, active-fixation ICD leads should be considered to limit the risk of electrode dislodgment.

Fibrinolytic therapy and n-acetylocysteine in the treatment of patients with acute myocardial infarction: its influence on authentic plasma hydroperoxide levels and polymorphonuclear neutrophil oxygen metabolism

Recently it has been demonstrated that the administration of n-acetylocysteine (NAC), in combination with streptokinase, significantly diminished oxidative stress in patients with myocardial infarction. The aim of our study was to assess the influence of NAC treatment, as adjunct therapy in an evolving myocardial infarction, on the polymorphonuclear count, superoxide anion and hydrogen peroxide levels and nitric oxide production by PMNs and authentic plasma hydroperoxide (ROOH). Treatment of patients with NAC in addition to reperfusion therapy was accompanied by a significant decrease in the number of circulating polymorphonuclear neutrophils. However, the oxygen metabolism of PMNs was not affected by NAC administration. The concentration of authentic plasma hydroperoxide was significantly reduced by the administration of NAC which suggests diminished oxidative stress during acute myocardial infarction.

Electrical atrial remodeling assessed by monophasic action potential and atrial refractoriness in patients with structural heart disease

The present study was performed to assess the effect of induced atrial fibrillation (AF) on atrial monophasic action potentials (MAPs) and atrial refractory period (ERP) in patients with structural heart disease. An electrode MAP catheter was placed in the right atrium to continuously measure atrial potential duration (APD90) in 13 patients (coronary artery disease, 10 patients; dilated cardiomyopathy, 2 patients; hypertrophic cardiomyopathy, 1 patient) without spontaneous AF episodes. AF was induced by rapid atrial stimulation (300-1500/min). If sinus rhythm returned within 10 minutes, AF was reinduced. The atrial ERP was measured during atrial pacing at a basic cycle length of 550 ms before AF induction and after its conversion.

RESULTS

The mean atrial ERP and the atrial APD90 before AF was 242 +/- 34 ms and 256 +/- 23 ms, respectively. ERP and APD90 shortening was observed after 3 minutes of AF. After 11 +/- 0.5 min (10 min 20 s-13 min 10 s) of AF, ERP and APD90 reached their minimal values of 72% +/- 13% and 71% +/- 10% of baseline, respectively. ERP and APD90 returned to their initial values within 10 minutes after conversion of AF. A tendency toward longer duration of consecutive AF episodes and facilitation of their induction was observed.

CONCLUSION

The present study confirms that short episodes of AF modify the electrophysiological properties of the atria in humans. In patients with structural heart disease, induced atrial fibrillation shortens the atrial ERP as well as the atrial APD90. The changes were reversible within 10 minutes after arrhythmia termination.

[Evaluation of nitric oxide metabolites concentration in patients with type I diabetes]

Nitric oxide (NO) mainly known as a relaxing factor, serves a wide variety of other functions in different tissues. It is quickly metabolized to NO2- and NO3- in humans. The aim of the study was to estimate plasma nitrite anion (NO2-) concentration in type 1 diabetic patients. The study was performed in 30 well metabolically controlled patients (18 female and 12 male, aged 30.2 +/- 10.6 years, duration of diabetes 8.4 +/- 6.8 years. HbA1c 6.5 +/- 1.2%) (group A) and 20 poorly metabolically controlled patients (12 female and 8 male, aged 29.8 +/- 9.8 years, duration of diabetes 8.0 +/- 4.8 years, HbA1c 11.2 +/- 1.6%) (group B). The concentration of NO2- was measured with the use of a calorimetric micromethod, where nitrate reductase catalyses the conversion of NO3- to NO2-. The NO2- plasma concentration was significantly higher in diabetic patients in comparison to controls. The highest NO2- concentration was noticed in the group of well metabolically controlled diabetic patients (group A, group B, healthy subjects: 41.99 +/- 4.02, 33.33 +/- 2.44, 16.68 +/- 2.16 mumol/l, respectively, p < 0.05, p < 0.0001). The nitrite concentrations did not correlate with HbA1c (r = -0.03, p > 0.05). The results support the concept that metabolism of nitrite oxides in diabetes is disturbed independently from the degree of metabolic control.

New insight into repolarization abnormalities in patients with congenital long QT syndrome: the increased transmural dispersion of repolarization

There is evidence from experimental studies that the time interval from the peak to the end of T-wave reflects the transmural dispersion in repolarization (electrical gradient) between myocardial "layers" (epicardial, M-cells, endocardial). Since Congenital Long QT Syndrome (LQTS) is considered to be classical disease or repolarisation abnormalities, we performed the present study to assess the transmural dispersion of repolarization in LQTS patients. The study group consisted of 17 patients: 7 LQTS pts and 10 pts from the control group. In each patient the 24-hour ECG recording was performed on magnetic tape. The interval from the peak to the end of the T-wave (TpTo) was automatically measured by Holter system during every hour as a measure of transmural dispersion of repolarisation. Thereafter the mean TpTo from 24-hours was calculated. In addition the spatial QT dispersion was measured from 12 lead ECG and 3 channel Holter tape as a difference between the shortest and the longest QT interval between leads. The values were compared between groups using the Anova test. TpTo was 79.6 +/- 9.6 ms (72-92 ms) in LQTS group and 62.4 +/- 7.5 ms (51-70) in the control group (p < 0.001). In LQTS group TpTo was significantly longer at night hours 72.5 +/- 2 when compared to day hours 87.4 +/- 8 (p < 0.01). The spatial QT dispersion was significantly higher in LQTS patients when compared to control, both in 12-lead standard and Holter ECG. Congenital long QT syndrome is associated with increase in both transmural and spatial dispersion of repolarization. The extent of prolongation of the terminal portion of QT in patients with congenital long QT syndrome is greater at night sleep hours compared to daily activity.