Increased nationwide use of green spaces in Norway during the COVID-19 pandemic

In recent years, there has been growing concern about the decline in human green space use and nature-based recreation in Western countries. While some evidence suggests that the COVID-19 pandemic led to increased recreational mobility in urban green spaces, it is unclear whether the pandemic led to nationwide changes in green space use in both densely and less densely populated neighborhoods, as well as whether social inequalities in green space use were reinforced or attenuated by the pandemic. To address these questions, we used daily nationwide aggregated mobility data from more than 2 million cell phone subscribers in 14,331 geographical grids across Norway to examine potential changes in mobility in green spaces as measured by the normalized difference vegetation index (NDVI) during the pandemic. Additionally, we controlled for weather conditions, holiday periods, and neighborhood sociodemographic characteristics. The results from linear mixed model analyses showed a 9.4% increase in recreational visits in the greenest spaces during the pandemic. Notably, this increase was most prominent in neighborhoods of low socioeconomic status (SES) and was observed in both high- and low-population density neighborhoods, although the increase was somewhat stronger in neighborhoods with low population density. Our study findings suggest that the COVID-19 pandemic has played a role in increasing nationwide green space use in Norway and potentially narrowing the gap of green inequalities, thus highlighting the importance of preserving and promoting green spaces as a public health resource, particularly in disadvantaged neighborhoods.

How subcultures emerge

Sympatric speciation is typically presented as a rare phenomenon, but urban subcultures frequently emerge even in the absence of geographic isolation. Is there perhaps something that culture has but biological inheritance does not that would account for this difference? We present a novel model that combines assortative interaction and multidimensional inheritance. Our computer simulations show that assortment alone can lead to the formation of cohesive clusters of individuals with low within-group and large between-group variability even in the absence of a spatial separation or disruptive natural selection. All it takes is a proportionality between the variance of inputs (cultural 'parents') and outputs (cultural 'offspring'). We argue that variability-dependent inheritance cannot be easily accomplished by genes alone, but it may be the norm, not the exception, in the transmission of culture between humans. This model explains the frequent emergence of subcultures and behavioural clustering in our species and possibly also other cultural animals.

Adolescents' psychosocial well-being one year after the outbreak of the COVID-19 pandemic in Norway

The COVID-19 pandemic has dramatically restricted adolescents' lives. We used nationwide Norwegian survey data from 2014-2021 (N = 227,258; ages 13-18) to examine psychosocial outcomes in adolescents before and during the pandemic. Multilevel models revealed higher depressive symptoms and less optimistic future life expectations during the pandemic, even when accounting for the measures' time trends. Moreover, alcohol and cannabis use decreased, and screen time increased. However, the effect sizes of all observed changes during the pandemic were small. Overall, conduct problems and satisfaction with social relationships remained stable. Girls, younger adolescents and adolescents from low socio-economic backgrounds showed more adverse changes during the pandemic. Estimated changes in psychosocial outcomes varied little with municipality infection rates and restrictions. These findings can inform means and interventions to reduce negative psychological outcomes associated with the pandemic and identify groups that need particular attention during and after the pandemic.

Pattern formation in reaction-diffusion systems with piecewise kinetic modulation: An example study of heterogeneous kinetics

The study of pattern emergence together with exploration of the exemplar Turing model is enjoying a renaissance both from theoretical and experimental perspective. Here, we implement a stability analysis of spatially dependent reaction kinetics by exploring the effect of a jump discontinuity within piecewise constant kinetic parameters, using various methods to identify and confirm the diffusion-driven instability conditions. Essentially, the presence of stability or instability in Turing models is a local property for piecewise constant kinetic parameters and, as such, may be analyzed locally. In particular, a local assessment of whether parameters are within the Turing space provides a strong indication that for a large enough region with these parameters, an instability can be induced.

All-Optical Scheme for Generation of Isolated Attosecond Electron Pulses

We theoretically propose an all-optical scheme for generation of isolated electron pulses with subfemtosecond durations for ultrafast electron microscopy and diffraction. The scheme is based on simultaneous longitudinal and transverse momentum modulation of freely propagating electrons at two distinct frequencies via ponderomotive interaction with tailored light fields of three phase-controlled laser pulses in vacuum. After a drift distance, an attosecond electron pulse train is formed with the individual pulses displaced in the transverse direction. Spatial filtering of the electron beam by an aperture leads to isolation of an individual attosecond pulse with a duration of <100  as. Subfemtosecond isolated electron pulses will enable direct space-time imaging of attosecond electronic dynamics in atoms, molecules, and solids with atomic spatial resolution, allowing us to directly observe phenomena such as electron tunneling or electron-electron interaction in strong laser fields of few-cycle laser pulses.

Simple technique for the compression of nanojoule pulses from few-cycle laser oscillator to 1.7-cycle duration via nonlinear spectral broadening in diamond

We report on a simple approach for the compression of few-cycle laser pulses generated in an ultrafast laser oscillator to a duration corresponding to 1.7 cycles of near-infrared light (compression factor of 1.44) by nonlinear spectral broadening in diamond and subsequent dispersion compensation using chirped mirrors. After the spectral broadening, the pulse spectrum spans over almost an octave (580-1000 nm at the -10  dB level). The pulses are compressed by broadband-chirped mirrors and a wedge pair to a duration of 4.5 fs measured by spectral phase interferometry for direct electric-field reconstruction (SPIDER). The properties of the broadened spectrum and their modelling by numerical solution of a 1D nonlinear Schrödinger equation show that the main source of spectral broadening is self-phase modulation, whereas stimulated Raman scattering does not play a significant role.

Ponderomotive Generation and Detection of Attosecond Free-Electron Pulse Trains

Atomic motion dynamics during structural changes or chemical reactions have been visualized by pico- and femtosecond pulsed electron beams via ultrafast electron diffraction and microscopy. Imaging the even faster dynamics of electrons in atoms, molecules, and solids requires electron pulses with subfemtosecond durations. We demonstrate here the all-optical generation of trains of attosecond free-electron pulses. The concept is based on the periodic energy modulation of a pulsed electron beam via an inelastic interaction, with the ponderomotive potential of an optical traveling wave generated by two femtosecond laser pulses at different frequencies in vacuum. The subsequent dispersive propagation leads to a compression of the electrons and the formation of ultrashort pulses. The longitudinal phase space evolution of the electrons after compression is mapped by a second phase-locked interaction. The comparison of measured and calculated spectrograms reveals the attosecond temporal structure of the compressed electron pulse trains with individual pulse durations of less than 300 as. This technique can be utilized for tailoring and initial characterization of suboptical-cycle free-electron pulses at high repetition rates for stroboscopic time-resolved experiments with subfemtosecond time resolution.

Acceleration of sub-relativistic electrons with an evanescent optical wave at a planar interface

We report on a theoretical and experimental study of the energy transfer between an optical evanescent wave, propagating in vacuum along the planar boundary of a dielectric material, and a beam of sub-relativistic electrons. The evanescent wave is excited via total internal reflection in the dielectric by an infrared (λ = 2 μm) femtosecond laser pulse. By matching the electron propagation velocity to the phase velocity of the evanescent wave, energy modulation of the electron beam is achieved. A maximum energy gain of 800 eV is observed, corresponding to the absorption of more than 1000 photons by one electron. The maximum observed acceleration gradient is 19 ± 2 MeV/m. The striking advantage of this scheme is that a structuring of the acceleration element's surface is not required, enabling the use of materials with high laser damage thresholds that are difficult to nano-structure, such as SiC, Al₂O₃ or CaF₂.

Optical gating and streaking of free electrons with sub-optical cycle precision

The temporal resolution of ultrafast electron diffraction and microscopy experiments is currently limited by the available experimental techniques for the generation and characterization of electron bunches with single femtosecond or attosecond durations. Here, we present proof of principle experiments of an optical gating concept for free electrons via direct time-domain visualization of the sub-optical cycle energy and transverse momentum structure imprinted on the electron beam. We demonstrate a temporal resolution of 1.2±0.3 fs. The scheme is based on the synchronous interaction between electrons and the near-field mode of a dielectric nano-grating excited by a femtosecond laser pulse with an optical period duration of 6.5 fs. The sub-optical cycle resolution demonstrated here is promising for use in laser-driven streak cameras for attosecond temporal characterization of bunched particle beams as well as time-resolved experiments with free-electron beams.

Coherent phonon dynamics in micro- and nanocrystalline diamond

We report on the time-resolved coherent anti-Stokes Raman spectroscopy of phonon dephasing in micro- and nanocrystalline diamond films. The dephasing times T(2) were found to be dependent on the morphology of diamond films (average size of crystals and content of nondiamond carbon phase) and changed from 0.7 to 1.72 ps. The dephasing times were found to be temperature independent in the range 10-295 K. In addition to diamond Raman active phonon mode at 1332 cm(-1), we investigated also the dynamics of a broad Raman peak at 1530 cm(-1) which is present in samples with higher content of nondiamond sp(2) hybridized carbon phase. This peak was found to be homogenously broadened with very fast dephasing (T(2)~50 fs).

[Evaluation of anterior cruciate ligament reconstruction using anterior tibial muscle tendon allograft]

PURPOSE OF THE STUDY

Injury to the anterior cruciate ligament (ACL) frequently results in the development of knee instability. This is managed by ACL reconstruction using autogenous or allogeneic grafts. This study presents a comprehensive evaluation of the patients with ACL reconstruction using a tendon allograft harvested from the anterior tibial muscle (ATM).

MATERIAL AND METHODS

The group under study comprised 53 patients, 33 men and 20 women, with unilateral ACL reconstruction while the other knee was intact. The average age was 32.4 years (17 to 51) and the average follow-up was 33,4 months (21 to 53). Clinical evaluation included the Tegner and Lysholm scores and questionnaire-based satisfaction rating. Functional assessment included measurements of the range of motion and thigh circumference. Knee stability was determined using the pivot shift test, Lachman test and one-leg hop test. ACL laxity was measured on a GNRB® arthrometer. Placement of the tibial and the femoral tunnel on radiographs was assessed by the method of Harner.

RESULTS

All patients reported their willingness to undergo the surgery again. The average pre-operative Tegner score improved from 7.17 (4-10) to 6.45 (2-10; p = 0.0001). The average post-operative Lysholm score was 87 points (47-100). At final follow-up, the full range of motion was recorded in 39 patients (74%), while the remaining patients exhibited only insignificant restriction of knee motion in comparison with the pre-operative status. The results of the Lachman test were negative in 38 patients (71.7%) while the pivot shift test was negative in 52 patients (98.1%). In the one-leg hop test, 44 patients (83%) were able to jump on the treated leg for a distance longer than 90% of the distance done on the healthy leg. The GNRB test at a force of 134N showed an anterior shift of the proximal tibia by 2.2 mm (0.1-9.3) on the average. The tibial tunnel was placed in zone B in 48 patients (90.6%) and the femoral tunnel was most often located to zone D (n = 47; 88.7%).

DISCUSSION

The choice of tissue for ACL reconstruction is still being discussed. In some centres an ATM tendon allograft is used only in revision surgery while, in other centres, it is also employed in primary procedures. Recent studies on ACL surgery suggest that outcomes are relatively independent of the material used for reconstruction. In view of evidence-based medicine, more well-conducted multicentre clinical trials are needed to optimise indications for allograft ACL reconstruction.

CONCLUSIONS

The ACL reconstruction using an ATM tendon allograft showed good clinical outcome at a minimum follow-up of 21 months. The method can be recommended not only for revision ACL reconstruction but also in primary reconstructions particularly in elderly patients. The present-day technology of producing allografts maintains tissue biomechanical characteristics and reduces risks for transmission of infection to a minimum.

[Therapy with implantable cardioverter-defibrillators (ICD) in the early of third millenium]

The patients without ventricular arrhythmias with markers of high risk of sudden cardiac death are indicated for ICD implantation today. Last generation of ICD systems are equipped with high capacity batteries, with many automatic functions, capabilities of data sending and possibilities of prediction of worsening of heart failure. Nowadays ICD systems offers not only elimination of the risk of sudden cardiac death but reduction of symptoms of chronic heart failure through the resynchronization therapy, too.

[Analysis and comparison of cohorts of patients with implantable cardioverter-defibrillator in primary and secondary prevention]

OBJECTIVE

The aim of this study was an analysis of patients with ICD implanted in primary prevention (PP) in long-term follow-up and comparison with data obtained in secondary prevention patients (SP).

PATIENTS AND METHODS

We assessed 73 patients with PP ICD and 138 patients with SP ICD. Males were in majority with 88% in PP group and 78% in SP group. The average age was 63 years. Majority of patients suffered from coronary artery disease. The mean ejection fraction (LV EF) was 28% in PP patients and 38% in SP patients. The number of affected coronary arteries and medication were similar in both groups. We compared the occurrence of intercurrent diseases, malignant arrhythmias, inappropriate therapies, hospital readmissions and patients' survival.

RESULTS

PP patients had lower LV EF ejection fraction (p < 0.001), higher number of revascularized arteries (p < 0.001) and lower occurrence of inappropriate therapies and arrhythmic storms (p < 0.001). There was higher number of patients with diabetes (p = 0.009), dyslipidemia (p < 0.001) and cerebral artery disease (p = 0.017) among those in PP group. Renal insufficiency was related to a higher risk of death.

CONCLUSIONS

Patients with PP ICD implantation have lower LVEF, and more intercurrent diseases then patients with ICD implanted form SP reasons. Their myocardium is more often revascularized and the occurrence of inappropriate therapy is low. Arrhythmic storm is a typical feature of patients with ICD implanted in secondary prevention.

Nonlinear optical properties of nanocrystalline diamond

We report on investigation of nonlinear optical phenomena in nanocrystalline diamond prepared by microwave plasma enhanced chemical vapour deposition. We observed the upconverted photoluminescence, the second and the third harmonic generation and Z-scan signal. The value of the third order nonlinear susceptibility was estimated. Our results show that nonlinear optical properties of nanocrystalline diamond have many features of the bulk diamond affected to some extent by the presence of grain boundaries.

[Influence of spontaneous ventricular premature beat coupling interval on the value of heart rate turbulence]

The heart rate turbulence is promising marker of a sudden cardiac death. The aim of the study is to evaluate the influence of the ventricular premature beat (VPB) coupling interval on the values of turbulence onset (TO) and turbulence slope (TS) parameters in the three groups of patients--"healthy" with ventricular premature beats, pts post myocardial infarction (MI) and pts with chronic heart failure with the left ventricle ejection fraction (LVEF) < 0.35.

PATIENTS AND METHODS

382 pts were examined: healthy--149, post MI--123 and LVEF < 0.35 - 110. The distribution ofVPB was analyzed and the values ofTO and TS were evaluated according to the coupling intervals of VPB--in the intervals 00-50, 51-100 (% of RR interval) and in the intervals 34-66 and 67-100 (% of RR interval).

RESULTS

The coupling interval of spontaneous ventricular premature beats cause the statistically significant variability HRT values in all three groups of pts.

CONCLUSION

The values of TO in the groups of post MI pts and pts with chronic heart failure are higher (risky for sudden cardiac death) after VPB with longer coupling intervals (50-100%, event. 67-100% of RR interval). The TS values are lower (risky for sudden cardiac death) after VPB with longer coupling interval, too. For evaluation of HRT we should use the VPBs with long coupling intervals.

[Complications with the pocket of cardiostimulator]

BACKGROUND

The number of patients with pacemakers is icreasing. The first reason is longer survival, the second reason is widening indications to cardiostimulation. Along with increasing numbers of performances, we have to recken larger number of complications and these complications solve so, that we avoid more serious damage of a patient.

METHODS AND RESULTS

In our article we focused an possible complications in the area of pacemaker pockets, monitored their appearence, watched the type of complication, the danger of the creation infection endocarditis and we present our own experiences with solving such complications. From the total numer of 3978 surgical interventions was 141 patients indicated for the revision of the pocket.

CONCLUSIONS

Repeated controls of the pocket and early reported of the patients to the specialised clinic is necessary for the safety of tke patients with pacemakers.

[Analysis of the effect of circadian rhythm on the heart rate turbulence in patients without evidence of organic heart disease]

Some studies have demonstrated circadian incidence of sudden cardiac death (SCD), ventricular ectopies, acute coronary syndromes and heart rate variability. One of new parameters applied in non-invasive stratification of sudden cardiac death is heart rate turbulence (HRT). Detection of circadian oscillations in HRT and optimised measurement of HRT can increase the positive predictive value of HRT as a sign of SCD risk. The set consisted of 48 patients in a sequence order aged 45 +/- 12 years (of which 23 men and 25 women), indicated for Holter monitoring ofventricular ectopies who had good left ventricular function with LV EF 0.53 +/- 0.11. HRT was measured in two-hour intervals within a 24 hour period, followed by an analysis of circadian dependence of HRT. A significant circadian oscillation in the TS (turbulence slope) parameter was recorded. No circadian signs were detected for the TO (turbulence onset) parameter. The project is supported by grant no. NR/8478-3.

[Analysis of circadian rhythm influence to heart rate turbulence in patients post myocardial infarction with left ventricular dysfunction]

BACKGROUND

Some study reported circadian occurence of sudden cardiac death, ventricle ectopic activity, acute coronary syndromes and heart rate variability. Heart rate turbulence (HRT) is one of a new markers of noninvasive stratification of sudden cardiac death.

METHODS AND RESULTS

We have evaluated HRT in 120 consecutive patiens post myocardial infarction in mean age 62.7+/-12.4 years (90 M, 30 W), indicated for ecg Holter monitoring with LVEF 0.45+/-0.12 in 2hours interval during 24 hours. We have analysed circadian variation of the HRT.

CONCLUSIONS

The statistically significant circadian patterns were found in turbulence slope parameter of HRT. No significant changes for turbulence onset parameter were described.

[Do we always have the possibility to treat "lege artis"?]

The case-history occupies of a case of acute cardiac insufficiency in a patient at early postoperative period, who underwent a small surgical operation. Apparently the banal operation became the starting mechanism of life threatening cardiopulmonary insufficiency. Transthoracic echocardiografic diagnostic process not gave us the unambiguous response about a cause of that distressed state. The primary clinical consideration of the pulmonary embolization was not ambiguously acknowledged, though nor excluded. The clinical had to decided, whether the heparinization or the thrombolysing treatment was justified.

[Long-lasting survival of patients with implantable cardioverter-defibrillators implanted for secondary preventive reasons]

BACKGROUND

The effectiveness of therapy with implantable cardioverter-defibrillators is usually evaluated according to the total mortality of ICD patients. The aim of this study is to analyse the total mortality of long-term followed ICD patients and to evaluate mortality according to the main diagnosis and analyse the influence of revascularization in patients with coronary artery disease.

METHODS AND RESULTS

We have observed 138 consecutive patients in mean age of 62.0+/-12.2 year (108 M, 30 F) with mean LVEF 0.38+/-0.14, who had ICD implanted for malignant ventricular arrhythmias from X/95 to XII/02 from secondary preventive reasons. The mean follow-up was 47.35 months. 99 patients had coronary artery disease, 16 dilated cardiomyopathy, 5 right ventricle dysplazia, 4 LQT syndrome, 1 valvular disease and 13 pts were without structural heart disease. The total mortality of the group of patients was 22% (31 patients). The terminal heart failure was the main cause of death in our pts--in 84% of the cases. We had no sudden death in our group of pts. The highest mortality (27%) was in pts with coronary artery disease, nobody died in the group of pts without structural heart disease. The higher mortality was in patients in pts where the revascularization was not possible before ICD implantation (38% versus 20%) One-year survival of the whole group of pts covered 90% and two-year survival was 87%.

CONCLUSIONS

The survival of ICD pts is shorter if coronary artery disease is present and there is no possibility to revascularize pts before ICD implantation.

[Comparison of the prevalence of non-invasive risk markers of the sudden cardiac death in patients treated by thrombolysis and by percutaneous transluminal coronary angioplasty]

BACKGROUND

Myocardial infarction survivors may develop a higher risk of sudden cardiac death. The risk markers: left ventricular ejection fraction, ventricular premature beats, late potentials on averaged ECG, baroreflex sensitivity and heart rate variability are used as non-invasive stratification markers.

METHODS AND RESULTS

Occurrence of the autonomic and morphologic dysfunction risk markers in the myocardial infarction patients treated by thrombolysis and by primary percutaneous transluminal coronary angioplasty (PTCA) is compared. We studied a cohort of 48 acute myocardial infarction survivors treated by primary PTCA and 96 patients treated by thrombolysis.

CONCLUSIONS

Patients treated by primary PTCA had significantly lower occurrence of premature ventricular beats and pathological parameters of the heart rate variability.

[Defibrillators--end of sudden cardiac death?]

The ventricular fibrillation is still the main cause of a sudden cardiac death, even though it was described 155 years ago in experiment (M. Hoffa 1849) and its therapy--defibrillation--has been known since 1947 (C. Beck). In Europe 2500 inhabitants suffer from cardiac arrest daily and 90% is caused by ventricular fibrillation. A key interval for an effective defibrillation seems to be 3-8 minutes from the begining of a cardiac arrest. Automated (automatized) external defibrillators (AED) have been used for last 15 years, especially in USA. However it is still unclear how many devices will be needed and where to place them. We don't know if they improve the prognosis of patients with out of hospital cardiac arrest during ventricular fibrillation. The individualisation of the risk of a sudden cardiac death has brought a new method to the clinical practise--implantation of cardioverter-defibrillator (ICD). Their efficacy in reduction of total mortality was verified first in the field of secondary prevention--in patients after cardiac arrest (AVID study) and than in the field of primary prevention--in patients with risk markers (left ventricle dysfunction, non sustained ventricular tachycardias) but without sustained malignant arrhythmia in anamnesis (MUSTT, CIDS, MADIT I, MADIT II). Defibrillators (external, automated, implantable) obviously don't mean the end of the sudden cardiac death. The incidence of sudden cardiac death can be reduced significantly with prevention (nutrition, prevention of CAD) and one attention should be drawn to the fact even in the future.

[Specific complications in the treatment with implantable cardioverter-defibrillators]

BACKGROUND

Using implantable cardioverter-defibrillators in treatment of malignant ventricular arrhythmias revealed new complications specific to this therapy. Inappropriate therapy, arrhythmic storm and device related proarrhythmia belong to the most significant complications. The authors describe specific complications in a group of ICD patients, analyze their etiology and prognostic value. There are some recommendations for the management of specific complications.

METHODS AND RESULTS

138 consecutive patients underwent ICD implantation between 1994-2001. Median follow-up was 47,35 months. Average left ventricular ejection fraction was 38 +/- 14% and 71% of patients suffered from coronary artery disease. From the total of 2490 arrhythmic episodes 1490 were evaluated in detail. 253 episodes (17%) were classified as inappropriate therapy. The most common etiology of inappropriate therapy was atrial fibrillation with rapid ventricular response (68%), atrial flutter (13%) and sinus tachycardia (11%). After the therapeutic intervention, 65% of them remained free of inappropriate therapy. There were 38 arrhythmic storms in 19 patients as another serious complication.

CONCLUSIONS

All the observed arrhythmic episodes were ventricular tachycardias (p<0.04). Patients with arrhythmic storm in history had significantly lower survival (p<0.05). The risk factors of cardiac nonsudden death were: age >66 years, left ventricular ejection fraction <35% and arrhythmic storm history. The authors present recommendations for the treatment of the most common specific ICD complications.

[Intracardiac electrocardiography in the diagnosis and therapy of arrhythmia]

The recording of intracardial electrocardiograms (IECG) has made good progress in the arrhythmology during last 15 years. First the aim was to describe the characteristics of the conduction system of the heart (Hisogram recording), followed by the evaluation of pathologies of the conduction system (meaning bradyarrhythmias), electrical activation of the myocardium when tachyarrhythmia is ongoing for diagnosis and punctual localization of accessory pathways during endocardial mapping. The next logical step as a reaction to the knowledge of endocardial mapping was the evaluation of new therapeutic methods--DC followed by radiofrequency ablations--nonpharmacological therapeutic antiarrhythmic procedures, usually used in electrophysiology labs of cardiological departments. Nowadays pacemakers are equipped with possibilities of intracardial atrial and ventricular signal recording which enables the use of accesorial antiarrhythmic functions. Intracardial electrocardiogram recording plays the dominant role in implantable cardioverter-defibrillators, where the main part of algorithms for detection and discrimination is based on the electrocardiograms. From both the diagnostic and therapeutic points of view intracardial signal recording is playing an important part in clinical practice in arrhythmology these days.

[Circadian rhythms in cardiovascular diseases--arrhythmias]

Circadian patterns have been observed for variety of cardiovascular disorders, including cardiac arrhythmias, sudden cardiac death, cerebrovascular events, episodes of stable angina, unstable angina and acute myocardial infarction. The morning predominance of these events has been well documented in a number of large population studies. This fact provides the stimulus for better understanding our own chronobiology and the periodicity of circadian rhythms which contribute to this predominance of adverse events in the morning hours. We now understand that a number of important physiological parameters such as heart rate, blood pressure, vascular reactivity, cardiac contractility, and various hemostatic factors all demonstrate a circadian pattern similar to that described for cardiovascular disorders. Several recent studies have also emphasize the importance of changes in posture, time of awakening, physical activity, mental stress as potential triggers. Circadian patterns have been observed for several supraventricular arrhythmias, premature ventricular beats, ventricular tachycardias including sudden cardiac death. The chronobiological therapeutic systems can help to prevent life threatening events.

[Use of chronobiology findings in therapy of cardiovascular diseases]

The concept of homeostasis in biology postulates that there is constancy of the intern milieu. Thus is assumed the risk and exacerbation of disease are invariable and independent of the time of day, day of month, and month of year as are the responses of patients to diagnostic tests and medications. Findings from the field of chronobiology, the study of biological rhythms, challenge the concept of homeostasis and the many assumptions and procedures of clinical medicine based on it. It is now recognized that human functions have daily, weekly, monthly and yearly biological rhythms. Plants, animals, and insects also have chronobiological rhythms. Circadian patterns have been observed for variety of cardiovascular disorders, including cardiac arrhythmias, sudden cardiac death, cerebrovascular events, episodes of stable angina, unstable angina and acute myocardial infarction. The morning predominance of these events has been well documented in a number of large population studies. It is now recognized that circadian and other rhythms of the gastrointestinal tract and vital organs are capable of significantly affecting the pharmacokinetics and dynamics of cardiovascular and other medications. This means that the effects of therapeutic interventions administered in identical doses in the morning versus the evening may not be equivalent. The prevention and treatment of cardiovascular disease must take into account chronobiological factors.

[Circadian rhythms in cardiovascular diseases--ischemic heart disease]

Several key advances in understanding of pathophysiology now provide the opportunity to develop improved treatment and prevention strategies. First, the importance o mechanism of plaque rupture and thrombosis in onset of myocardial infarction. Second, there has been demonstrated, that plaques that lead to acute occlusion often have only a mild degree of stenosis. A third advance that has stimulated the field has been the recognition that time of onset of cardiac events is not random but instead shows a circadian pattern of onset. In the decade since the 1985 observation by Muller a spol. that the frequency of onset of myocardial infarction peaks at 9 a.m., numerous publications have supported this observation not only for myocardial infarction, but also for sudden cardiac death, transient myocardial ischemia, and stroke. Refinement of these epidemiological observations has led, first, to the conclusion that the morning peak in disease onset is due in part to the physical and mental stressors associated with morning awakening and activity and, second, that stressors such as heavy physical activity and anger can trigger acute cardiovascular events.

[The intracardiac electrocardiogram in the diagnosis of arrhythmias]

During the last 15 years in arrhythmology brisk development of the use of endocardial electrocardiograms (IECG) occurred. At first the objective was to describe the characteristics of the conduction system of the heart (recording of Hisogram), next assessment of pathological features of the conduction system (such as bradyarrhythmias), electric activation of the myocardium in existing arrhythmias with the outcome of the diagnosis and accurate localization of additional pathways in endocardial mapping. The next logical step reacting to knowledge of intracardial mapping was the development of new therapeutic methods--DC and subsequently radiofrequency ablation--non-pharmacological therapeutic antiarrhythmic approaches which are by now commonly used in electrophysiological catheterization laboratories of cardiological departments. Some contemporary pacemakers can also record intracardial atrial and ventricular IECG and make it possible to use additional antiarrhythmic stimulation. A dominant position is held by the IECG in implantable cardioverters-defibrillators where on the high standard recording of IECG a considerable proportion of detection and decision-making algorithms of this equipment is based. Recording IECG is an integral part of clinical arrhythmological practice from the diagnostic as well as therapeutic aspect.

[Multiorgan failure in pulmonary embolism]

The case-history presents a case of unexpected pulmonary embolization manifestated in a middle-aged patient closely before operation (classical cholecystectomy). The severe respiratory insufficiency was the consequence, which proceeded to a metabolic dysbalance and the state of disseminated intravascular coagulation. The prognosis was very serious, but the patient recovered after 4 weeks of complete resuscitative care. The authors would like to initiate the discussion about the way and timing of antithrombic preoperative preparation in elderly patients and in those with a high risk of thromboembolic complications.

[Sudden cardiac death--a problem in cardiology today]

More than 2500 persons from European population die of sudden cardiac death every day. Nearly 90% of these cases are caused by malignant ventricular arrhythmias, which develop most frequently on the basement of structural heart disease. Some subpopulations of patients can be marked as a high risk for sudden cardiac death according to the today stratification procedures and can be treated in a pharmacological or nonpharmacological ways. The ways are as follows: a chronic therapy with beta-blockers agents, therapy of congestive heart failure, myocardial revascularization and implantation of cardioverter-defibrillator. The prognosis of patients treated in those ways in comparison with conservatively treated groups is very good.

[Implantable cardioverter-defibrillators in the prevention of sudden cardiac death]

The aim of this work is to characterize and analyse the spectrum of therapies delivered from implantable cardioverter-defibrillators (ICD), to evaluate their effectivity and to mark the most effective types of antitachycardia stimulations (ATP), cardioversion (CV) and defibrillation (CD). To compare our results with references and give precautions of trouble-shootings. Our patients had implanted ICDs according to standard criteria for ICD implantations. Before discharge from hospital we performed predischarge test of their ICD. Than we followed them periodically each three months. We have observed 72 ICD pts (55 M, 17 F) in the mean age of 62.7 +/- 12.2 years the with mean LVEF was 0.37 +/- 0.11. The mean follow-up was 21 +/- 12.8 months. Each examination was managed through anamnesis of symptoms accompanying the beginning of arrhythmia, the sensation of ICD therapy by patient, followed by interrogation of the ICD memory. All obtained episodes were analysed. During the follow-up 1023 episodes of malignant ventricular arrhythmias were detected and effectively terminated. 7 pts died. During the therapy the ATP reached 83% in comparison with CV, CD which reached only 17%. The dominating symptoms were palpitations and presyncopes. In comparison with initial arrhythmias leading to implantations of ICDs (ventricular fibrillations for most of the cases--54%) the significantly higher number of spontaneous episodes were caused by monomorphic ventricular tachycardias VT (92.0%). We had no sudden cardiac death in our pts. In the indicated pts with a high risk of sudden arrhythmic death, the ICD therapy is characterized as very effective and is associated with high safety, low discomfort and when up to date algorithms for detection being used, then only adequate part of the inappropriate therapies occurs (10% patients, 3.2% from the number of episodes). The therapy by implantable cardioverter-defibrillators has had an important role in treating pts with life-threatening ventricular arrhythmias.

[Electric programmed ventricular stimulation using a permanent cardiac pacing system--a noninvasive method in arrhythmia]

BACKGROUND

Complex forms of ventricular arrhythmias often occur in patients with an implanted permanent cardiac pacing system. Some of the pacemakers are provided with software which allows electrophysiological testing of the cardiac conduction system by coupling with an external diagnostic pacemaker via their programmer. This method is non-invasive.

METHODS AND RESULTS

In a group of 26 patients (19 males, 7 females) with an implanted pacemaker (Paragon III, Synchrony III, Sensorithm--all Pacesetter) complex ventricular arrhythmias were observed (class Lown IVa and higher). In these patients the electrical stability of the myocardium was tested by the described method (protocol: incremental pacing 90-220 bpm, pacing drives 110 bpm and 140 bpm with 1-3 extrastimuli). Complex ventricular arrhythmias were induced in 42% patients (n = 11), in this subgroup 55% (n = 6) was non-sustained ventricular tachycardia, 36% (n = 4) sustained ventricular flutter, 9% (n = 1) sustained ventricular tachycardia. Patients with non-sustained ventricular tachycardia were treated with beta-blockers, in the others the effective therapy was selected according to electrophysiological testing (amiodarone in 4 patients, ICD in 1 patient). During a 24-month follow-up the overall mortality was 7.7% (n = 2), sudden death mortality was 3.8% (n = 1).

CONCLUSIONS

Programmed ventricular stimulation performed by a permanent cardiac pacing system is a simple and above all non-invasive method with no need for fluoroscopy. It can be repeated several times. It is not possible to pace from the right ventricle outflow tract. This is the main disadvantage. Nevertheless, by using non-invasive risk stratification methods (echocardiography, signal averaged ECG, heart rate variability, baroreflex sensitivity, dispersion of QT interval) the patients in need of an invasive study can be identified. This method can be considered an alternative screening method and a standard part of the investigation of the algorithm in patients with a previously implanted pacemaker.

[Optimalization of rate adaptation using Holter functions in DDD/R pacemakers]

Introduction of the pacing rate adaptation according to the momentary metabolic needs added other programmable parametres which demand physician's attention during the initial postimplantation programmation and also in follow-up of pacemaker patients. The parametres setting is strictly individual with a need of feedback control. In some devices it is enabled by Holter functions as a part of pacemaker software. These methods were used to set the rate adaptive parametres in the group of 23 patients with implanted DDD/R pacemaker. The walking stress test was used. Model follow-up situations are presented in 3 case reports. Using Holter functions enables the physician to put patient's subjective complains in relation with actual heart rate--this is used to optimize the parametres of rate adaptation. The authors consider the Holter functions a necessary part of rate adaptive pacemaker software.

[Selection and long-term effect of treatment in vasovagal neurocardiogenic syncope]

BACKGROUND

Syncope state performed by transient loss of consciousness connected with a postural tone decrease present still an important therapeutical problem. The authors use HUT testing for discovering of vasovagal etiology of a syncope. The aim of the study was to find out the optimal medication in treatment and prevention of VVS by repeated HUT drug testing in a group of positive patients.

METHODS AND RESULTS

We examined a group of 300 patients (172 female and 128 male) age 35.26 +/- 13.47 years with an anamnesis of recurrent syncopes by HUT test. In 83 patients (27%) we set up a diagnosis of VVS. Thirteen patients (15.66%) were only followed without medication. The rest of the group (70 patients, 84.34%) started with a therapy. Testing was performed by repeated HUT according to the "Westminster protocol". HF and BP were measured by FINAPRESS 2,300 made by Ohmeda. The effective therapy was found in 64 patients (91.43%) of the group. For various reasons the therapy was changed and retested in 9 patients (14.06%). Beta1 selective beta-blockers were used in 51 patients (80.96%) theophyllin in 5 patients (7.94%), etilephrin in 6 patients (9.52%) and clonidine in 1 patient (1.59%).

CONCLUSIONS

The therapy of VVS should be set-on according to the effective drug selection by serial drug testing in repeated HUT tests. The article shows a high predictive value of negative HUT test for a long term effect of tested therapy.

[Head-upright tilt table test: a new method for diagnosis of vasovagal neurocardiogenic syncope]

The head upright tilt table test (HUT) has been unambiguously included into the screening algorithm of syncopes. The HUT is based on exposing patients to orthostatic stress. This easy, cheap and safe test makes it possible to diagnose neurally-mediated vasovagal syncope (NMS). The pathophysiology of the NMS is based on the hypercontractility of the myocardium, when with the body being orthostatic, the venous return to the heart is lower and then followed by protecting mechanism--vasodilatation and bradycardia--both controlled by the CNS. Nowadays there is a tendency to integrate examination schedules of the HUT and all possible types of responses have been defined.

[Neural syncope--a current therapeutic problem]

Syncope, a state performed by transient loss of consciousness connected with postural tone decrease present still an important therapeutical problem. It can vary from a benign physiological body reaction to a life-limiting situation. The authors of the article present HUT-testing to be a simple, useful and safe method for discovering vasovagal mechanism of the syncope. They notice the experiences with treatment according to the HUT results. The most frequent types of therapy are the pharmacological and the pacing ones, when the former is appropriate for I and III class of VVS the latter then for the II. class. There are some big studies in progress now which should bring more information about this clinical problem.

[Seasonal effect on serum levels of thyroid hormones in German shepherds and dachshunds and their health status]

A relatively frequent prevalence of dermatoses in summer has drawn our attention. Dermatoses of endocrine origin occur very often. We have noticed the deterioration of skin changes in animals with hypothyroidism. Bubeník et al. (1983), Webster et al. (1991), Reiter et al. (1988) reported that changes in concentrations of thyroid hormones were found in fallow-deer, sheep and hamsters due to the effect of temperature and season. Based upon this knowledge we have decided to observe the health status and function of the thyroid gland in two randomly selected groups of various size dogs--German shepherd and dachshund during four seasons. We observed following parameters: concentration of triiodothyronine (T3), thyroxine (T4), cholesterol (Chol) and total lipids (TL) in the blood serum, average temperatures in individual seasons. Blood was always withdrawn fasting in the morning from vena antebrachii. Concentrations of T3 and T4 were determined by the commercial kits RIA-test-T4 and RIA-test-T3 (Human-Lab, Kosice, Slovak Republic). The levels of cholesterol and total lipids were determined by the BIO-LA-tests (Lachema, Brno, Czech Republic). March, April, May were included into spring season; June, July, August into summer; September, October, November into autumn; and December, January, February into winter. The Slovak Hydrometeorologic Institute in Kosice provided the values of average temperatures in observed seasons. The average temperatures in individual seasons were the following: spring +9.8 degrees C, summer +18.4 degrees C, autumn +8.5 degrees C, winter -1.2 degrees C. During the observed period concentrations of cholesterol and total lipids ranged within the reference values in both breeds.(ABSTRACT TRUNCATED AT 250 WORDS)

[The role of the HUT test (head upright tilt table test) in patients with syncope of uncertain etiology]

The authors have examined 73 patients at the mean age of 36.8 +/- 15.3 (M:34, F:39). All the pts have suffered from recurrent presyncopes or syncopes the etiology of which has not been diagnosed by previous internal, neurological or psychiatric examination. Before the HUT the patients have undergone a complete cardiological examination. The HUT has been carried out according to the modificated Westminster protocol, the blood pressure and the heart rate have been monitored continuously. The end-point of the HUT has been a presyncope or a syncope, viewed as positive. The positive pts have been divided into 4 groups according to the changes of their blood pressure and heart rate during a presyncope or a syncope-mixed, cardioinhibitory A, cardioinhibitory B and vasodepressor responses. Out of 73 pts there have been 27 pts (37%) with positive responses and 46 (63%) with negative responses. The mixed type has been achieved in 12 pts, cardioinhibitory A-in 5 pts, cardioinhibitory B-in 2 pts, vasodepressoric in 8 pts. The mean time needed for positive response during the native HUT has been 17.7 +/- 11 min, after activating with isoproterenol for 2.6 +/- 1 min. The achieved results correlate with data in medical literature. The test activated with isoproterenol increases its sensitivity. There have not been any complications marked within the examined group.

CONCLUSION

The HUT has been unambiguously included into screening algorithms of syncopes as an easy, cheap, safe examination with good sensitivity and specificity.

[Surgical treatment of necrotizing hemorrhagic pancreatitis with a prolonged course]

The authors describe the course of acute haemorrhagic necrotizing pancreatitis complicated by prolonged septicaemia, the formation of abscesses, acute haemorrhage and a intestinal fistula--"Critically ill patient". Early surgical elimination of necrotic septic foci is the prerequisite of effective treatment and cure. In the diagnosis CT and magnetic resonance prove most useful. With the latter so far little experience as been assembled. Ultrasonographic visualization technique is insufficient for the diagnosis of focal changes in the area of the pancreas.

[Late complications of unrecognized post-traumatic diaphragmatic hernias]

The authors reflect, based on two case-histories, on problems of diagnosis and operation of undiagnosed post-traumatic diaphragmatic hernias. In one instance a perforation of the diaphragm was missed during operation of a piercing heart injury and in the second case the operation was made only after incarceration of the stomach and spleen one year after a blunt chest injury.