Seroprevalence of bluetongue serotype 8 in cattle in the Netherlands in spring 2007, and its consequences.

A cross-sectional study was carried out in spring 2007, at the end of the first bluetongue outbreak season, to determine the geographical spread of bluetongue virus serotype 8 (btv-8) infection in cattle in the Netherlands and the consequences for some production parameters. Blood samples from cattle submitted to the laboratory of the Dutch Animal Health Service for other voluntary and obligatory health programmes were tested serologically for btv-8. In total, 37,073 samples were tested and 659 (1.78 per cent) were seropositive. The samples came from 5436 herds, of which 45 per cent of herds had only one sample submitted from them. The prevalence was highest in the south of the country, where the outbreak had started, and decreased towards the north. In 340 herds more than 50 per cent of cattle were tested, of which 156 herds were located in infected compartments, and in 37 of these herds (10.9 per cent) at least one positive cow was detected. The average within-herd prevalence in the 37 herds was 39.3 per cent: 2.2 per cent in 11 dairy herds, 68.4 per cent in 20 small-scale herds and 14 per cent in four suckler cow herds. The prevalence differed significantly between herd types but did not show a geographical trend. The average net return for milk production amounted to euro2417/cow/year and it decreased significantly on average by euro48/cow/year in the bluetongue-infected dairy herds during the bluetongue period. On the small-scale farms, the incidence of mortality increased by 3.2 (95 per cent confidence interval [CI] 1.2 to 9.1) times in the infected herds during the bluetongue period, but the voluntary culling rate decreased by a factor of 2.3 (95 per cent CI 1.1 to 4.8).

The membrane fluidity concept revisited by polarized fluorescence spectroscopy on different model membranes containing unsaturated lipids and sterols.

Quantitative analysis of time-resolved anisotropy measurements of DPH or TMA-DPH in lipid vesicles yields more than one mathematically correct solution. The solutions differ with respect to the average orientation and to the reorientational dynamics of the probe molecules in the bilayer. This leads to quite opposite results regarding the effects of cholesterol on membrane fluidity. One solution predicts an increase in fluidity, the other a decrease. Angle-resolved fluorescence depolarization (AFD) measurements of probes in oriented lipid bilayers enable determination of the average orientation of the probes in the bilayer and, if the fluorescence decay function is known, of the reorientational dynamics. Analysis of AFD measurements of DPH and TMA-DPH show that increasing unsaturation leads to a decrease in molecular order and a decrease in reorientational dynamics (= fluidity) of the probes. At temperatures above the phase transition of the lipids, the addition of cholesterol causes an increase in molecular order and an increase in reorientational dynamics (= fluidity). The plant sterol stigmaterol, which is structurally closely related to cholesterol, has different effects than cholesterol. The effects vary with the structure of the surrounding lipids. The membrane fluidity concept as it was originally proposed by Chapman attempts to describe the structural and dynamic properties of lipids in a membrane using one single parameter indicated as 'membrane fluidity'. Our results show that it is necessary to distinguish between structural parameters describing molecular order and motion parameters describing molecular dynamics, thus supporting a similar suggestion by Seelig and Seelig. In order to be useful, the membrane fluidity concept has to be limited to the parameters describing molecular dynamics.

Intima-media thickness of peripheral arteries in asymptomatic cigarette smokers.

BACKGROUND AND PURPOSE: Although it is known that smoking is associated with an increase in arterial wall thickness, most studies have been performed in heterogeneous groups of older age, already suffering from atherosclerotic diseases or having additional cardiovascular risk factors. The purpose of this study is to assess the effect on arterial wall thickness of the carotid and femoral artery in cigarette smokers. METHODS: In a cross-sectional study, intima-media thickness of the common and internal carotid artery, carotid bulb and common femoral artery was determined with the use of a B-mode ultrasound device, in 184 (44.3+/-9.0 years) cigarette smokers for whom smoking is the single cardiovascular risk factor. Comparisons were made with 56 non-smokers, matching in age and gender. RESULTS: The posterior walls of both carotid bulbs (right: P=0.0005; left: P=0.02) and of the internal carotid arteries (right: P=0.004; left: P=0.003) as well as the posterior wall of the right common carotid artery (P=0.02) and of the right common femoral artery (P<0.0001) were thicker in smokers. CONCLUSIONS: Cigarette smoking as the single cardiovascular risk factor causes wall thickening of the carotid and femoral arteries, which indicates that early atherosclerosis is already present in smokers entering middle age.

D-dimer determination to assess regression of deep venous thrombosis.

A number of studies evaluating deep venous thrombosis (DVT) have demonstrated that plasma levels of thrombotic and fibrinolytic parameters change during treatment, but the relationship between thrombus regression and evolution of these markers remains unknown. The objective of the present study was to correlate levels of D-Dimer (DD) with thrombus regression as assessed by duplex scanning. From 44 patients treated for acute DVT, DD were determined at diagnosis and at the end of initial heparin therapy of at least 5 days. Thrombus regression was measured by repeated duplex scanning at diagnosis and after 1 and 3 months. DD significantly decreased during heparin treatment as compared with values at presentation. DD levels were significantly higher in the group of patients without normalization of the DVT after 3 months (p = 0.003). A ninefold excess tendency was seen for DD levels > 1200 ng/ml at the end of initial treatment to be associated with poor resolution of the DVT [odds ratio 9.0, 0.95 confidence interval (CI) 2.3-35.4]. When the patients with an established malignancy were excluded, the differences were even more significant (p = 0.0004 for DD levels after initial treatment and an odds ratio of 17.5, 0.95 CI 3.3-92.5). These results suggest that increased DD levels after the initial phase of treatment are related to poor resolution of DVT after 3 months. These findings contribute to further insight into the process of thrombus regression. Furthermore high DD levels might help to identify the patients with a poor prognosis and could be useful to judge the efficacy of anticoagulant treatment.

Dynamic vessel wall properties and their reproducibility in subjects with increased cardiovascular risk.

OBJECTIVE: To determine reproducibility figures of dynamic arterial wall properties such as cross-sectional compliance (CC) and distensibility (DC) in subjects with increased cardiovascular risk, in comparison with healthy adults. METHODS: A total of 34 persons were divided into three groups with varying cardiovascular risk factors. Diameters (D) and diameter changes (deltaD) during the heart cycle of both common carotid (CCA) and right common femoral (CFA) arteries were measured by a vessel wall movement detector system. Blood pressures (BP) were recorded non-invasively by a semi-automated oscillometric device. CC (=piD(deltaD/2deltaP) in unit mm2/kPa) and DC (=2deltaD/D)/deltaP in unit 10(-3)/kPa) were calculated from the above-mentioned parameters. Measurements were performed twice during one visit and twice again with a time interval of at least 3 days to determine intra-observer intra- and intersession variability. RESULTS: Reproducibility figures of CC and DC of the CCA varied between 8 and 12%, and between 13 and 22% for the CFA. Intra-observer intra- and intersession variability were similar in the three groups. CONCLUSIONS: In our studies the reproducibility of dynamic vascular wall properties determined by ultrasound was good. Despite differences in the absolute values for CC and DC in groups with increased cardiovascular risk, mean reproducibility figures remained at a similar level (8-12%) as in healthy volunteers.

Progressive arterial wall stiffening in patients with increasing diastolic blood pressure.

BACKGROUND: Hypertension is an established risk factor for cardiovascular disease. Risk factor patterns for various cardiovascular complications are different. We studied the relationship between increasing diastolic blood pressure and arterial wall dynamics of various peripheral arteries in hypertensives to increase insight in the variability of properties within the arterial tree. METHODS: Eighty-six untreated hypertensives participated in this cross-sectional study. The study-population was divided into quartiles with increasing diastolic office blood pressure. Cross-sectional compliance and distensibility coefficients of the carotid and femoral arteries were determined, using a vessel wall movement detector system (Wall Track System). RESULTS: Diameters of both common carotid arteries enlarged (right: from 7.4 +/- 0.2 to 7.9 +/- 0.2 mm) while cross-sectional compliance (right: from 0.61 +/- 0.04 to 0.42 +/- 0.04 mm(2)/kPa) and distensibility coefficients (right: from 14.2 +/- 1.0 to 9.0 +/- 1.0 10(-3)/kPa) gradually dropped with increasing diastolic blood pressure. Cross-sectional compliance and diameter of the right common femoral artery remained unchanged while distensibility coefficient decreased although less gradually when compared with the carotid arteries. CONCLUSIONS: In untreated hypertensives gradual arterial wall stiffening of the carotid arteries occurred with increasing diastolic blood pressure. Gradual changes were less clear in the common femoral artery which points to the heterogeneity of the arterial tree.

Ultrasound determination of the effect of progestogens on the endometrium in postmenopausal women receiving hormone replacement therapy.

Progestogen challenge tests were performed in 81 postmenopausal women receiving hormone replacement therapy (HRT) with progestogen addition as required. The number of tests carried out totalled 159. The effect of progestogen use on endometrial thickness was determined by vaginosonography. The endometrial shedding caused by progestogen was correlated with the withdrawal bleeding pattern. As expected, in the majority of cases (145 out of 159), progestogen brought about endometrial shedding. In most but not all cases, shedding was attended by withdrawal bleeding. The intensity and the duration of withdrawal bleeding were positively correlated with endometrial shedding. No correlation was found between endometrial shedding and the onset of withdrawal bleeding.

Monitoring of oestrogen replacement therapy by vaginosonography of the endometrium.

To prevent hyperplasia and carcinoma of the endometrium during oestrogen replacement therapy (ORT), the addition of progestogens once a month is considered mandatory. However, there is no sound scientific basis for this assumption. As the addition of progestogens has several disadvantages, it is important to minimize the frequency of progestogen addition. Vaginosonography is a rather new technique which has not yet been used for monitoring ORT. In this study the increase in endometrial thickness, as measured by vaginosonography, was taken as an indicator of stimulation of the endometrium by oestrogens. Oestrogen treatment was started in post-menopausal women with little endometrium (thickness less than 3 mm). As long as there was virtually no increase during oestrogen treatment, no progestogen was added, but where considerable growth occurred (greater than 3 mm) progestogen was administered. By means of vaginosonography the growth of the endometrium can be monitored precisely on an individual basis. It is thus possible to distinguish women with a slow growing endometrium from those with an endometrium that grows fast. In this way it will perhaps become possible to minimize progestogen addition during ERT by tailoring dosage to individual requirements.

Two years of smoking cessation does not reduce arterial wall thickness and stiffness.

BACKGROUND: Smoking cessation rapidly reduces cardiovascular risk. The pathophysiological mechanisms involved are still being debated. We measured structural and functional arterial wall properties of the femoral and carotid arteries after smoking cessation to investigate their possible role in cardiovascular risk reduction. METHODS: Out of 127 smokers, 33 proved to stop smoking for two years. They were compared with 50 nonsmokers and 55 persistent smokers in a prospective study. Cross-sectional compliance and distensibility coefficients as well as intima-media thickness of both carotid arteries and of the right common femoral artery were measured ultrasonographically at baseline and 3, 6, 12 and 24 months after smoking cessation. The nonsmoking and persistent smokers group were measured twice at an interval of 24 months. RESULTS: Persistent smoking and two years of smoking cessation did not affect cross-sectional compliance and distensibility coefficients. Although at baseline intimal-medial layers were thicker in smokers, the change over time in intima-media thickness did not differ significantly between all three groups. CONCLUSION: Two years of smoking cessation was not accompanied by a slower progression or a regression in intima-media thickness nor by an improved cross-sectional compliance or distensiblity coefficient. Nevertheless, smoking cessation should be recommended as it reduces cardiovascular risk rapidly after smoking cessation.

Cardiac magnetic resonance imaging in daily practice in a peripheral medical centre: description of the first 383 patients.

BACKGROUND: Cardiac magnetic resonance (CMR) imaging has evolved over the last decade into an indispensable diagnostic instrument. CMR imaging noninvasively provides structural, functional and morphological information with high spatial resolution and an unlimited field of view. Since October 2006 the VieCuri Medical Centre in Venlo has a CMR scanner at its disposal. OBJECTIVES: The goal of this study was to analyse the impact of CMR imaging on diagnosis and treatment in daily practice in the setting of a medium-volume peripheral hospital. METHODS: All patients who underwent CMR imaging between October 2006 and November 2008 were included in this analysis. The medical history before and after the CMR scan, the application form for CMR imaging and the outcome of the scans were reviewed. CMR images, obtained using a 1.5-T magnetic resonance imaging system, were reviewed by a multidisciplinary team. RESULTS: In 235 patients CMR imaging demonstrated one or more abnormalities, whereas CMR imaging did not identify any abnormalities in 148 patients. CMR imaging confirmed an expected finding in 166 cases, identified an unexpected condition in 69 cases, ruled out an expected finding in 59 cases and ruled out a suspected condition in 89 cases. Due to better insight into diagnosis, CMR imaging resulted in a change of treatment in 166 of the total of 383 CMR scans (43%). CONCLUSION: In a relevant number of cases CMR imaging leads to a change in the treatment of a patient, proving the value of CMR imaging as a diagnostic modality. Therefore, CMR imaging is an excellent opportunity for peripheral medical centres to improve efficiency and the standard of patient care. (Neth Heart J 2010;18:524-30.).

Dynamic response of a neonatal catheter-manometer system in situ.

OBJECTIVE: The purpose of this study was to develop, validate, and apply a flush-pulse method to determine the dynamic response of a neonatal catheter-manometer system (CMS) in situ. METHODS: In the flush-pulse method, the opened fast-flush valve of the CMS is closed; as a result, the fluid column in the CMS is impacted. This procedure can be done without affecting the net flow of infusion fluid. We validated the method in laboratory conditions by comparing 14 paired results obtained with this method to the results obtained using a generally accepted step-response method. The measurable values are the resonance frequency (fr) and the damping coefficient (delta). The analysis of the flush-pulse method in situ is complicated by the patient's blood pressure wave. A remedy for this problem that is based on the first derivative of the pressure signal has been developed. The flush-pulse method is applied 14 times in situ. RESULTS: In laboratory settings, the fr ranged from 12.5 to 64.0 Hz and delta ranged from 0.14 to 0.32. The correlation coefficient was 0.99 for fr and 0.91 for delta. We found four overdamped systems in situ (delta > 1). In other systems fr values between 8.5 and 41.0 Hz and delta values between 0.16 and 0.72 were observed. The dynamic response in situ appeared to deteriorate with time due to routine intensive care procedures. CONCLUSIONS: The flush-pulse method proved to be a valid test for determining the dynamic response. The results obtained in situ emphasize the need for a regular evaluation of the dynamic response of the neonatal CMS in order to assess the shape of the pressure wave.

DDD(R) pacing with automatic mode switch in patients with paroxysmal atrial fibrillation following AV nodal ablation.

Optimal pacing in patients with paroxysmal atrial fibrillation/flutter following AV node ablation remains to be determined because VVIR pacing cannot restore AV synchronization and conventional DDD(R) pacing cannot properly cope with atrial tachyarrhythmias. The objective of the present investigation was to study the clinical outcome of 16 of these patients who received a new DDDR pacemaker with an automatic mode switch (Thera DR; Medtronic) immediately after AV node ablation. Arrhythmia-related symptoms before ablation were palpitations in 12, dizziness in 10, exercise intolerance in 8, and syncope in 6 patients. Pacing modes at hospital discharge were DDDR (n = 14) and DDD (n = 2) with an activated mode switch in all patients. After 1 month 12 patients were symptom free. Clinical events occurred in 4 patients (palpitations in 2, dizziness in 1, chest pain in 1, and fatigue in 1), which could be relieved in 3 patients. At discharge as well as at the 1-month follow-up, Holter ECG recorded a total of 12 episodes of atrial fibrillation in 5 patients, which were correctly detected by the pacemaker and followed by mode switching. At the 3-month follow-up (n = 14), 12 patients were symptom free and 2 continued to report symptoms which could not be resolved. All patients remained on an automatic mode switch in either the DDDR (n = 12) or DDD (n = 2) mode. There were no hints of inappropriate mode switching or reports of pacemaker syndrome, and there were no new symptoms related to automatic mode switching. The patients studied were highly symptomatic before implantation due to paroxysmal atrial fibrillation/flutter. After the first follow-up, 81% of the patients reported no symptoms. Paroxysmal atrial fibrillation/flutter combined with a high-degree AV-block seems no longer to be a contraindication for AV-synchronous pacing.

[Frequency of atrial pacing in patients with intermittent atrial fibrillation and 2nd or 3rd degree atrioventricular block. Thera DR Pacemaker Study Group]. / Häufigkeit der Vorhofstimulation bei Patienten mit intermittierendem Vorhofflimmern und AV-Block 2. oder 3. Grades. Studiengruppe des Thera DR Schrittmachers.

UNLABELLED: Patients with 2nd or 3rd degree AV-block and paroxysmal atrial fibrillation could be suitable for VDDR pacemakers, if they are not or rarely paced in the atrium. We studied in 23 of these patients 1 month after DDDR pacemaker implantation, how often they were paced in the atrium with usual pacemaker programmings; patients with < 10% atrial pacing were compared with patients with > or = 10% atrial pacing. In case automatic mode switch was programmed, the number of mode switch episodes was assessed as a marker for the frequency of atrial tachyarrhythmias. Atrial pacing < 10% of the time occurred in seven, pacing from 10 to 19% in six, from 20 to 29% in two, and > or = 30% of the time in eight patients. Five of the seven patients with < 10% atrial pacing were paced in the DDD mode, but only four of 16 patients with > or = 10%. Usual clinical findings were unable to predict patients with rare atrial pacing. Patients with < 10% as well as with > or = 10% atrial pacing had < 10 mode switch episodes in 67% each. CONCLUSIONS: During short-term follow-up after DDDR pacemaker implantation 30% of the patients with paroxysmal atrial fibrillation and second or third degree AV-block, with present usual pacemaker programmings, rarely had atrial pacing, that means < 10% of the time. These patients would be probably suitable for VDDR pacemakers. Rare atrial pacing had no influence on the occurrence of automatic mode switch episodes.

Comparison of electrical characteristics between a steroid-eluting single-pass VDD lead and a standard steroid-eluting ventricular lead. Thera Pacemaker Study Group.

Compared to regular ventricular leads, single-pass VDD leads have two additional floating electrodes proximal to the ventricular tip, which enables them to detect atrial signals. Because of the latter, VDD leads are thicker than ventricular leads, which could affect ventricular pacing. The purpose of the present study was to compare ventricular pacing of a steroid-eluting single-pass VDD lead (CapSure VDD, Medtronic; n = 107) with the same steroid-eluting regular lead (CapSure SP, Medtronic; n = 39) implanted in the ventricle; both leads were connected to the same types of pacemakers. At implantation, pacing thresholds were measured at 0.5-ms pulse duration and impedance by means with the PSA. At discharge, as well as after 1 and 3 months, pulse duration thresholds were determined at 2.5 V pulse amplitude and impedance by telemetry. At implantation, pacing thresholds and impedance were not different in the VDD (0.38 +/- 0.16 V; 691 +/- 122 omega) and ventricular lead group (0.44 +/- 0.17 V; 648 +/- 150 omega). During follow-ups, no differences in pulse duration threshold were detected between the two groups neither at discharge (VDD = 0.05 +/- 0.03 ms; ventricular 0.05 +/- 0.02 ms), nor after 1 (VDD = 0.05 +/- 0.02 ms; ventricular 0.08 +/- 0.07 ms) and 3 months (VDD = 0.06 +/- 0.03 ms; ventricular 0.09 +/- 0.10 ms). There were also no significant differences for impedance at discharge (VDD = 675 +/- 113 omega; ventricular = 594 +/- 113 omega), after 1 (VDD = 678 +/- 131 omega; ventricular = 627 +/- 112 omega) and 3 months (VDD = 652 +/- 99 omega; ventricular = 628 +/- 105 omega). Pacing thresholds and impedance were neither significantly different at implantation nor during follow-ups between patients with steroid-eluting VDD leads and patients with an equivalent ventricular lead indicating that the thicker VDD lead does not affect ventricular pacing.

[Low stimulation impedance in pacemaker patients with cardiac diseases. The Thera Pacemaker Study Group]. / Niedrige Stimulationsimpedanz bei Herzschrittmacher-Patienten mit kardialen Erkrankungen. Die Thera-Schrittmacher-Studiengruppe.

BACKGROUND AND AIM OF THE STUDY: As increasing impedance of the pacing impulse decreases pacing current, high pacing impedance lowers pacing current and subsequently prolongs pacemaker longevity. The present assumption of a standard 500 ohms impedance disregards interindividual differences. In the present study, the interindividual range of pacing impedance was assessed at implantation. Additionally clinical parameters of patients with low pacing impedance were compared to those of patients with high values. PATIENTS AND METHODS: The same lead and the same pacemaker (CapSure VDD; Thera VDD; Medtronic) were implanted in 126 patients (79 men, 47 women, mean age 65 +/- 16 years). Patients with an impedance below or similar to the median were compared to patients with an impedance above the median in respect to clinical (age, gender, arterial hypertension, cardiac diseases such as coronary heart disease, valvular heart disease, cardiomyopathy) and electrical parameters (pacing threshold at 0.5 ms pulse duration, R-wave amplitude). RESULTS: Mean impedance was 687 +/- 121 ohms with a range from 333 to 1040 ohms and a median of 670 ohms. 64 patients had an impedance < or = 670 ohms and 62 patients > 670 ohms. Mean age, gender and the occurrence of arterial hypertension were similar in the two groups. Cardiac diseases occurred significantly (P < 0.01) more often in patients with lower (n = 23) than with higher impedance (n = 9). Intraoperative pacing thresholds and R-wave amplitudes were not different between the two groups. CONCLUSIONS: The range of pacing impedance was 707 ohms for the studied lead. Under consideration of permanent pacing with 2.5 V pulse amplitude and 0.5 ms pulse duration this would vary expected longevity of the implanted pacemaker from 7.8 to 9.3 years. Patients with lower impedance more often had cardiac diseases than patients with higher impedance.

Present day pacemakers for pulse generator exchange: is 3.5 V a sufficient nominal setting for the pulse amplitude? Thera Pacemaker Study Group.

Projected pacemaker longevity is calculated according to the nominal setting, which is 3.5 V for pulse amplitude in most present day pacemakers. The aim of this study was to test whether the nominal ventricular output setting of 3.5 V and 0.4 ms provides a 100% safety margin if these pacemakers are connected to implanted ventricular pacing leads. The study included 24 patients undergoing pulse generator exchange. The new pacemaker was either a Thera DR (n = 21) or Thera SR (n = 3) device. Ventricular pacing leads were implanted 70 +/- 38 months previously. Intraoperative measurements included pacing threshold at 0.5-ms pulse duration, impedance, and R wave amplitude. To achieve a 100% safety margin with 3.5 V, the cut-off pacing threshold is 1.7 V. At discharge it was assessed whether ventricular pulse amplitude remained at < or = 3.5 V or was programmed to > 3.5 V. At pulse generator exchange, pacing threshold was 1.2 +/- 0.5 V, including four patients with pacing thresholds > 1.7 V. Impedance was 587 +/- 189 omega and R wave amplitude was 12.8 +/- 4.8 mV. At discharge, ventricular pulse amplitude remained at the nominal setting in 13 patients, including 2 patients with high pacing thresholds at pacemaker exchange, and was programmed to < 3.5 V in 7 patients. Ventricular pulse amplitude was programmed to > 3.5 V in four patients. Two of these patients had high pacing thresholds (> 1.7 V/0.5 ms) at pulse generator exchange; the other two patients were programmed to > 3.5 V, although 3.5 V already provided a 100% safety margin. After pulse generator exchange, 92% of the patients could be paced with a 3.5-V pulse amplitude. Pacemakers were programmed in four patients > 3.5 V, but in only two of them to obtain a sufficient safety margin. High pacing thresholds at pulse generator exchange did not generally predict high pacing thresholds at discharge.

A prospective randomized comparison between fixed rate response programming and automatic rate response optimization in activity-triggered DDDR pacemakers. Thera Pacemaker Study Group.

Activity rate response programming depends on the physician's experience and on the limited knowledge of patient's daily activities. The present investigation compares a new continuous automatic adjustment of the activity rate response called rate response optimization (OPT) with fixed activity rate response programming (FIXED). At hospital discharge 37 patients with Thera DR pacemakers (Medtronic) were randomized either to FIXED (n = 20; 65 +/- 12 years, male n = 12) or to OPT (n = 17; 65 +/- 12 years, male n = 13). After 1 month's follow-up occurrence of complaints related to rate-responsive pacing and the percentage of pacing were assessed. Other activity sensor parameters were programmed according to clinical judgement and similarly distributed in the two groups. Activity rate response was 7.1 +/- 1.4 (FIXED) and 7.2 +/- 1.7 (OPT), activity threshold was medium in 9 (FIXED) and 8 (OPT), and medium/low in 11 (FIXED) and 9 (OPT) patients, respectively. No patient with FIXED had any complaints with respect to activity-triggered rate response. One patient with OPT reported palpitations due to rapid changes in the pacing rate leading to reprogramming of the pacemaker. Atrium and ventricle were paced in 56 +/- 31% (FIXED) and in 58 +/- 35% (OPT; not significant) and the atrium only in 4 +/- 10% (FIXED) and 0% (OPT; not significant), respectively. In the 17 patients programmed to OPT the pacemaker increased activity rate response in 5 and decreased activity rate response in 3 patients. In conclusion, as only 1 (3%) patient had complaints related to the activity rate response and fixed rate response programming according to clinical judgement already resulting in symptom-free DDDR pacing, no differences could be detected between the fixed rate response programming and rate response optimization.

[Intermittent atrial fibrillation/flutter: contraindication for implantation of a dual chamber pacemaker?]. / Intermittierendes Vorhofflimmern/-flattern: Kontraindikation für die implantation eines Zweikammerschrittmachers?

UNLABELLED: The programming of dualchamber pacemakers to DDD(R) mode is not recommended in patients with paroxysmal atrial fibrillation/flutter, because the pacemaker detects atrial fibrillation/flutter and paces the ventricle up to the pacemaker's upper tracking rate. Some newer pacemakers have the feature to switch automatically from DDD(R) to DDIR mode at the onset of atrial tachyarrhythmias. The aim of the study was to assess how many patients who received such a new DDDR pacemaker with automatic mode switch can be programmed to DDD(R) mode during follow-up. The dual-chamber pacemaker Thera DR (Medtronic) was implanted for clinical evaluation in 142 patients (65 +/- 16 years, male n = 86; female n = 56). Paroxysmal atrial fibrillation/flutter was present in 54 patients, with an additional 2nd or 3rd degree AV-block in 13 and no high-degree AV block in 22 cases; an AV node ablation was performed in 19 patients. Pacemakers were programmed to DDD(R) mode at discharge in 52 of 53, at month 1 in 44 of 46, and at month 3 in 28 of 30 cases. In respect to the programming to DDD(R) mode there were no statistically significant differences to patients without paroxysmal atrial fibrillation/flutter. CONCLUSION: Paroxysmal atrial fibrillation/flutter was present in 38% of the studied patients. During follow up more than 90% of the patients were paced in the DDD(R) mode.

[Comparison of active and passive fixation of steroid emitting atrial electrodes]. / Vergleich aktiver und passiver Fixation bei steroidfreisetzenden Vorhofelektroden.

UNLABELLED: Steroid-eluting screw-in leads (CapSure Fix 4068, Medtronic; n = 14) were compared to the same lead as a J-shaped tined electrode (CapSure SP 4524, Medtronic; n = 27, implanted in the atrium in patients receiving dual-chamber pacemakers. Follow-up were at discharge and after 1 month. Implantation (screw-in lead: 84 +/- 18 min; tined lead: 81 +/-29 min) and fluoroscopy times (screw-in lead: 7.3 +/- 4.9 min; tined lead 9.2 +/- 7.0 min) were similar in the two groups. At implant, P-wave amplitudes were similar with 4.8 +/- 1.6 mV (screw-in lead) and 4.0 +/- 2.6 mV (tinted lead), respectively. Compared to tined leads, the screw-in leads had higher pacing thresholds at 0.5 ms pulse duration (screw-in lead: 0.74 +/- 0.32 V; tined lead: 0.55 +/- 0.15 V; p = 0.02) as well as higher impedance (screw-in lead: 566 +/- 93 ohms; tined lead: 470 +/- 99 ohms; p = 0.01). Pulse duration thresholds at 2.5 V pulse amplitude were neither different at discharge (screw-in lead: 0.07 +/- 0.04 ms; tined lead: 0.06 +/- 0.05 ms) nor after 1 month (screw-in lead: 0.09 +/- 0.04 ms; tined lead: 0.06 +/- 0.06 ms). P-wave amplitudes > or = mV were observed at discharge in 14/14 (screw-in lead) 21/27 patients (tined lead), respectively, and after 1 month in 13/14 (screw-in lead) and 22/27 (tined lead) patients, respectively. Impedance of the screw-in lead was significantly higher with 693 +/- 84 ohms at discharge and 691 +/- 79 ohms after 1 month compared to the tined lead with 520 +/- 81 and 574 +/- 62 ohms (p = 0.001). No lead dislodgment was reported during follow-up. CONCLUSIONS: For the studied steroid-eluting leads active and passive fixation had neither at implantation nor during 1-month follow up any influence on P-wave amplitude. At similar pulse duration thresholds, impedance of the screw-in lead was significantly higher than for the tined lead. Higher impedance additionally reduces pacing current, if similar pacing impulses are delivered.