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HISTORY AND CLINICAL FINDINGS A 49-year-old man, an alcoholic for the past 7 years, complained of dizziness, palpitations and exertional dyspnoea (NYHA stage III). Physical examination revealed peripheral cyanosis, slightly raised jugular venous pressure, râles in the lung bases, a loud systolic murmur, maximal over the apex, and an enlarged palpable liver. INVESTIGATIONS Results of biochemical tests were unremarkable. The ECG showed sinus rhythm, 1 degree AV block and signs of left ventricular hypertrophy. Chest radiogram demonstrated cardiac dilatation and probably absent right superior vena cava (SVC). Long-term ECG monitoring during episodes of dizziness and one syncope revealed self-limited periods of unifocal ventricular tachycardia. Echocardiography and angiography showed bilateral ventricular dilatation with an ejection fraction reduced to 20%, as well as mild mitral and moderate tricuspid regurgitation but normal cardiac valves, suggesting a dilated cardiomyopathy. Coronary angiography was normal. No myocarditis was revealed on myocardial biopsy. The patient declined electrophysiological investigation. TREATMENT AND COURSE Amiodarone caused higher degree AV block. A temporary pacemaker lead was inserted via the persistent left SVC, amiodarone discontinued and later a pacemaker-defibrillator system (ICD) implanted, previous digital subtraction angiography having demonstrated a left SVC and absent right SVC. The transvenous electrode had been placed via the left subclavian vein, left SVC (anode), coronary sinus, right atrium into the right ventricle (cathode), and the pacemaker-defibrillator implanted subpectorally. Stable electrode position and correct ICD function has been documented over 2 years. 4 months after implantation bursts of ventricular tachycardia recurred every few minutes that responded to renewed amiodarone administration. CONCLUSION Good long-term results can be obtained with ICD electrodes implanted via a persistent LSVC.

WIEGAND, U.K.H., et al.: Incidence and Predictors of Pacemaker Dysfunction with Unipolar Ventricular Lead Configuration. Can We Identify Patients Who Benefit from Bipolar Electrodes? Unipolar ventricular leads were implanted in a considerable percentage of pacemaker recipients. There is little information on incidence and risk factors for unipolar pacemaker dysfunction using modern lead designs. Included in a cross-sectional analysis were 682 patients who fulfilled the following criteria: chronically implanted bipolar ventricular leads (> 1 year), intraoperative stimulation threshold 6 mV. Incidences of chest wall stimulation (CWS) at an output of twice the amplitude threshold and of myopotential oversensing (MPO) at a sensitivity of half the sensing threshold were assessed. Energy (0.60 [0.72] vs 0.63 [0.81] μJ) and sensing thresholds (8.31 [3.18] mV vs 8.47 [3.47] mV) did not differ between uni- and bipolar modes. While all pacemakers worked properly during bipolar configuration, malfunctions were observed in 5.9% of patients during unipolar configuration (CWS = 1.9%, MPO = 4.2%). Patient age > 76 years (hazard ratio HR 8.2; P < 0.001), heart failure ≥ NYHA Class II (HR 3.8; P < 0.001), and an antiarrhythmic therapy with Class I or III drugs (HR 3.3; P = 0.002) were independently associated with the occurrence of unipolar pacemaker dysfunction. Use of steroid-eluting leads reduced the probability of pacemaker dysfunction (HR 0.45; P = 0.03). Risk factors for unipolar ventricular pacemaker malfunction were higher age, heart failure, and antiarrhythmic drug therapy. Particularly in these patients, use of bipolar ventricular leads is beneficial.

Unexpected atrial fibrillation (AF) during implantation of an atrial pacemaker lead is sometimes encountered. Intraoperative cardioversion may lengthen and complicate the implantation process. This study prospectively investigates the performance of atrial leads implanted during AF (group A) and compares atrial sensing and pacing properties to an age- and sex-matched control group in which sinus rhythm had been restored before atrial lead placement (group B). Patient groups consisted of 32 patients each. All patients received DDDR pacemakers and bipolar, steroid-eluting, active fixation atrial leads. In patients with AF at the time of implantation (group A), a minimal intracardiac fibrillatory amplitude of at least 1.0 mV was required for acceptable atrial lead placement. In patients with restored sinus rhythm (group B), a voltage threshold1.5 V at 0.5 ms and a minimal atrial potential amplitude1.5 mV was required. Patients of group A in whom spontaneous conversion to sinus rhythm did not occur within 4 weeks after implantation underwent electrical cardioversion to sinus rhythm. Pacemaker interrogations were performed 3, 6, and 12 months after implantation. In group A, implantation time was significantly shorter as compared to group B (58.7 +/- 8.6 minutes vs 73.0 +/- 17.3 minutes, P0.001). Mean atrial potential amplitude during AF was correlated with the telemetered atrial potential during sinus rhythm (r = 0.49, P0.001), but not with the atrial stimulation threshold. Twelve months after implantation, sensing thresholds (1.74 +/- 0.52 mV vs 1.78 +/- 0.69 mV, P = 0.98) and stimulation thresholds (1.09 +/- 0.42 V vs 1.01 +/- 0.31 V, P = 0.66) did not differ between groups A and B. However, in three patients of group A, chronic atrial sensing threshold wasor = 1 mV requiring atrial sensitivities of at least 0.35 mV to achieve reliable atrial sensing. Atrial lead placement during AF is feasible and reduces implantation time. However, bipolar atrial leads and the option to program high atrial sensitivities are required.

In dual chamber pacemakers, atrial sensing performance is decisive for maintenance of AV synchrony. Particularly, the efficacy of mode switching algorithms during intermittent atrial tachyarrhythmias depends on the sensitive detection of low potential amplitudes. Therefore, a high atrial sensitivity of 0.18 mV, commonly used in single lead VDD pacemakers, was investigated for its efficacy and safety in DDD pacing. Thirty patients received dual chamber pacemakers and bipolar atrial screw-in leads for sinus node syndrome or AV block; 15 patients suffered from intermittent atrial fibrillation. Pace makers were programmed to an atrial sensitivity of 0.18 mV. Two weeks, 3, 9, and 15 months after implantation, P wave sensing threshold and T wave oversensing thresholds for the native and paced T wave were determined. The myopotential oversensing thresholds were evaluated by isometric contraction of the pectoral muscles. Automatic mode switch to DDIR pacing was activated when the mean atrial rate exceeded 180 beats/min. The patients were followed by 24-hour Holter monitoring. Two weeks after implantation, mean atrial sensing threshold was 1.81 +/- 0.85 mV (range 0.25-2.8 mV) without significant differences during further follow-up. Native T wave sensing threshold was < 0.18 mV in all patients. In 13% of patients, paced T waves were perceived in the atrial channel at the highest sensitivity. This T wave sensing could easily be avoided by programming a postventricular atrial refractory period exceeding 300 ms. Myopotential oversensing could not be provoked and Holter records showed no signs of sensing dysfunction. During a 15-month follow-up, 1,191 mode switch events were counted by autodiagnostic pacemaker function. Forty-two of these events occurred during Holter monitoring. Unjustified mode switch was not observed. In DDD pacemakers, bipolar atrial sensing with a very high sensitivity is efficient and safe. Using these sensitivity settings, activation of the mode switch algorithm almost completely avoids fast transmission of atrial rate to the ventricle during atrial fibrillation.

Heise, A., Peters, W., and Zahner, H. 1999. Phosphocholine epitopes in Eimeria bovis. Experimental Parasitology 92, 279–282.

Autonomic Control of the AV Node. Introduction: Following radiofrequency catheter ablation of AV nodal reentrant tachycardia (AVNRT), inappropriate sinus tachycardia may occur, possibly due to damage to autonomic cardiac nerve fibers. Furthermore, inducibility of AVNRT is often critically dependent on the autonomic balance. We investigated whether successful ablation of AVNRT is associated with an alteration of autonomic input to the sinus and AV nodes. Methods and Results: To estimate changes in the automatic modulation of the sinus and AV nodes, power spectra of beat-to-beat PP and PR intervals were analyzed from high-quality nighttime ECG recordings of 11 patients before and after radiofrequency application. Normalized HF power (nHF) of PP and PR intervals was used as an index of efferent vagal modulation and the LF/HF ratio as an index of sympathovagal balance of the sinus node (PP) and AV node (PR). Before ablation, LF/HFPP was 3.2 and nHFPP was 0.3 in the sinus node, For the A/V node, LF/HFPR was 1.2 and nHFPR was 0.5. Following ablation. LF/HFPP (3.5) and nHFPP (0.3) of the PP intervals did not change. Similarly to the sinus node, there were no changes in the autonomic modulation of the AV node, as both LF/HFPR (1.2) and nHFPR (0.5) remained unchanged. Conclusion: Our results indicate that autonomic control of the sinus und AV nodes is preserved following successful radiofrequency ablation of AVNRT. The effects of posteroseptal radiofrequency current application are not necessarily mediated by changes in the autonomic input to the AV node.

Inappropriate Discharge of an ICD. Introduction: Inappropriate discharses of an implantable cardioverter defibrillator (ICD) are troublesome to the patient and sometimes a difficult task for the physician trying; to identify and treat the cause. Methods and Results: For the first time, we report a mechanism of inappropriate ICD discharges during episodes of atrail flutter with a slow ventricular response and intermittent antibradycardia pacing. The episodes occurred in tow patients and were triggered by the unique sensing alogorithm of the Ventitex Cadence® V-100 in combination with the tripolar CPI Endotak® 072 transvenous defibrillation lead, which provides integrated bipolar sensing. Conclusion: Besides treatment of the underlying arrhythmia, reprogramming of the device, an electrode position far away from the atria, and true bipolar sensing will enhance the performance of ICD systems with respect to the episodes described here. In addition, more flexible sensing algorithms may. in the future, prevent this overall rare complication.

The pharyngeal and lorical cuticles of adult and larval Loricifera were investigated by transmission electron microscopy. LR White sections of larval and adult Loricifera were labelled with the lectin wheat germ agglutinin (WGA) conjugated to colloidal gold. The pharyngeal cuticle of Nanaloricus mysticusexhibits a multilaminate epicuticle and an amorphous basal layer with osmiophilic fibres. The lorical cuticle consists of an osmiophilic or trilaminate epicuticle, one to three amorphous layer(s), and a basal fibrous layer which is strongly labelled by the lectin-gold conjugate. Chitinase treatment or competitive inhibition with N-, N′-, N″-triacetylchitotriose exclude labelling almost completely, whereas competitive inhibition with N-acetyl-D-glucosamine does not affect labelling intensity. The binding of WGA in connection with competition experiments indicates the presence of chitin in the fibrous layer. In most areas of a section, three amorphous layers extend below the epicuticle of the Nanaloricidae. Only in favourably orientated sections can all three “amorphous” layers be seen to be formed by stacks of lamellae. Modified articulation sites with bundles of osmiophilic longitudinal fibres and an osmiophilic plate (Nanaloricidae only) occur in adult Loricifera, but not in the larval stages. The ultrastructure of the lorical cuticle of the Loricifera resembles that of other Nemathelminthes (= Aschelminthes). The morphology of the articulation sites and the number of lorical plates seem to differ between the Loricifera and Priapulida. Therefore, it is currently not possible to conclude whether the lorica of the Loricifera and Priapulida are homologous structures. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.

The ultrastructure of the pharynx of the first juvenile stage and of adult Oesophagostomum dentatum(Nematoda, Strongylida) is investigated by TEM. Additional light microscopical and SEM data are presented for the anterior alimentary canal of all life-history stages and for adult O. quadrispinulatum. Ultrathin sections of adult and the first juvenile stage O. dentatumare labelled with the lectin wheat germ agglutinin coupled to colloidal gold. The pharyngeal cuticle consists of a trilaminate epicuticle and an amorphous basal layer, which also exhibits individual fibres in adult worms. The pharyngeal cells of the first juvenile stage are already arranged as in the adult worm. In comparison with data for additional nematodes taken from the literature, a trilaminate epicuticle and an amorphous basal layer are postulated for the pharynx in the ground pattern of the Nematoda. Lectin-gold labelling reveals a strong binding to the pharyngeal cuticle of O. dentatum. Competitive inhibition experiments with N-acetyl-D-glucosamine and triacetylchitotriose, as well as treatment with chitinase, neuraminidase and sulphuric acid, indicate that the pharyngeal cuticle contains chitin. This finding is supported by staining of the pharyngeal cuticle by the fluorescent brightener calcofluor white in cryosections of O. dentatum. The occurrence of chitin is interpreted as an original character of the Nematoda. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.

It has been demonstrated that successful thrombolytic therapy is associated with a reduction of late potentials in the signal-averaged electrocardiogram (SAECG) recorded within 48 hours after hospital admission. This study extends these observations, using for the first time a longitudinal design investigating whether ischemia and its potential reversal by thrombolytic therapy are associated with dynamic changes in SAECG recordings obtained continuously for 8 hours after the start of therapy in patients with acute myocardial infarction (MI). SAECGs were obtained from 12 patients (2 women and 10 men; ages 63 +/- 13 years) with acute MI. The SAECG (X2 + Y2 + Z2)1/2 was generated with a high pass filter of 40 Hz, noise < or = 0.3 microV. Comparing the SAECG recordings during the first and eighth hours, there was a significant decrease in filtered QRS duration (fQRS; 119.5 +/- 17.1 vs 106.3 +/- 15.3 ms) and duration of the low amplitude signals < or = 40 microV of the terminal QRS (LAS40; 48.8 +/- 18 vs 34.2 +/- 14.2 ms), and increase of root mean square voltage of the last 40 ms of the QRS (t-RMS; 14.8 +/- 9.3 vs 37.8 +/- 34.4 microV) (rank test, P < or = 0.05). In this patient series, there was a significant improvement of fQRS, t-RMS, and LAS40 during the first 8 hours of acute MI, perhaps indicating reversal of ischemia with thrombolysis. Even during acute MI, these markers of delayed conduction allow investigation of intervention induced changes in myocardial conduction and possibly prediction of the patency of the infarct related artery using signal-averaging techniques.

UNLABELLED Efficient on-line digitization is the prerequisite for computerized analysis of the electrical phenomena occurring during defibrillation. Conventional hardware presently provides only limited time resolution. The performance of various digitization rates for recording of voltage, current, and calculation of derived quantities like impedance, energy, and defibrillator capacitance was investigated. It was assessed both experimentally and by computer simulation of a trapezoidal discharge (of 9 msec duration into a constant resistive load of 50 omega with a defibrillator capacitance of 132 microF). The accuracy achieved with different digitization rates is given. For example, an accuracy of 1% for analog-digital conversion for impedance calculation during this kind of DC shock requires a sampling rate of 8 kHz without, and a rate of 1 kHz with linear interpolation to correct for the hardware dependent error due to sequential sampling. CONCLUSION Highly efficient analog-digital conversion of delivered voltage and current during DC shocks is available within the limits of conventional inexpensive hardware.

Spectral analysis of heart rate variability is usually performed by Fast Fourier Transform. Here we demonstrate the self-affine properties of the human heart rate using a spectral analysis based on counting statistics. Each QRS complex is considered to be a point event and from the number of events N(Δt) in consecutive time windows Δt the variance is calculated. From the finding that the variance of N(Δt) follows a power law proportional to (Δt)1+b in case of 1/fb noise, it is shown that the variance of the heart rate as determined for windows of length Δt, i.e., N(Δt)/Δt, is proportional to (Δt)b−1. From a 12-day Holter recording, the scaling region could be determined to cover 0.16 to 0.000136 Hz. A function X(t) is self-affine if X(t) and X(rt)/rH have the same distribution functions. From the variance-time-curve, it can be shown that the exponent H is dependent on b with b=2H−1. In young healthy men, the parameter b fluctuates between 0.2 and 1.0 during 24 h and thus determines the self-affine scaling factor H=(b−1)/2 for the amplitude of heart rate, if the time axis is scaled by r. Thus, during periods of 1/f noise, the heart rate scales with H=0, and for periods of almost white noise, with H close to [Formula: see text].

Three layers of different electron density can be distinguished in the periostracum. Periostracal units of up to 900 nm length are merged into the outer fibrous layer and binding of gold-labelled lectin-WGA indicates the presence of chitin because it is labile to chitinase treatment. The periostracum is formed by the epithelia of the groove and the belt at the mantle edge. The distal and basal epithelium of the groove consists mainly of type A cells with an extended Golgi apparatus and apical vesicles. The presence of peroxidase and phenol oxidase indicates a function in tanning of the periostracum. In the proximal epithelium of the groove, type B cells with protruding apices add more material for periostracum formation. Type C cells secrete single periostracal units which are formed within single vesicles or larger vacuoles. Type D cells secrete electron-dense vesicles which also contain WGA-positive material. The distal cells of the belt are characterized by predominating strands of the rER while subapical vacuoles, to some of which WGA binds, dominate in the cells of the central part. In the belt, phenol oxidase and peroxidase can be localized in cisternae of the rER and the Golgi apparatus. Numerous control incubations indicate that, indeed, two different enzymes are localized.

Die Insekten sind charakterisiert durch eine Dreiteilung des Korpers: Kopf (Caput), Brust (Thorax) und Hinterleib (Abdomen). Der Kopf (Caput) besteht entwicklungsgeschichtlich aus sechs Segmenten. Ursprunglich sind ein Paar Gliederantennen, aus denen bei den meisten Insekten Geiselantennen wurden sowie drei Paar Mundwerkzeuge vorhanden. Die ungegliederten Mandibeln sind ursprunglich mit einem Gelenk (monokondyl), bei den meisten Insekten aber mit zwei Gelenken (dikondyl) versehen. Die beiden folgenden Paare von Mundwerkzeugen, die Maxillen, sind gegliedert und mit einem Taster (Palpus) ausgestattet. Das zweite Maxillenpaar ist vielfach zu einem einheitlichen Labium verwachsen.

Das Auffinden von Nahrungsquellen erfolgt vor allem aufgrund chemischer Reize, die mit den Haarsinnesorganen auf den Antennen wahrgenommen werden (s. 11.3). Bei der Nahorientierung spielen auserdem Sinnesorgane an den Tarsen und auf den Mundwerkzeugen, insbesondere den Palpen, eine Rolle. Die Wahrnehmungsfahigkeit kann im Alter auch bei den Insekten abnehmen. So kann bei der Schmeisfliege Phormia regina die Wahrnehmung von Zuckern bis zu 50% verringert sein. Parallel dazu konnen bis zu 50% der Sinneshaare am Labeilum nicht mehr funktionsfahig sein. Die Wahrnehmung von Fraslockstoffen fordert und verlangert die Nahrungsaufnahme, wahrend diese beim Vorhandensein von Frasabwehrstoffen (Frashemmstoffe) unterbrochen oder reduziert werden kann. Sinnesorgane zur Uberprufung der aufgenommenen Nahrung sind besonders im Cibarium vorhanden.

BACKGROUND We tested the hypothesis that action potential duration (APD) restitution of normal ventricular muscle cells is different during double premature stimuli (S3) compared with a single premature stimulus (S2). We propose a possible ionic mechanism for such a difference. METHODS AND RESULTS Action potentials and isometric tension were recorded simultaneously from isolated canine right ventricular trabeculae (2 x 2 x 10 mm) (n = 35). APD and tension restitution curves (APD) and peak tension versus diastolic interval [DI] of S2 and S3 were constructed by the extrastimulus method during pacing at 1,500 msec. The following results were obtained. 1) The APD restitution curve of S2 was different from that of S3. During the restitution of S2, an early biphasic upward hump was present at short DIs. In contrast, a smooth exponential rise was consistently seen during S3 restitution. 2) Peak tension remained significantly (p less than 0.001) lower during the restitution of S2 than during S3 restitution at all DIs tested. 3) The variation of APD during the initial 100 msec of DI was significantly longer during S3 than S2 (22 +/- 5 msec versus 41 +/- 5 msec, p less than 0.001). 4) Caffeine (2 mM, n = 5) and ryanodine (10 microM, n = 5) blocked cyclic variations of tension, presumably by blocking cyclic variations of intracellular calcium ion concentrations ([Ca2+]i), and eliminated the differences in APD restitution between S2 and S3. 5) Nisoldipine at high (5 microM) but not at lower (2 microM, n = 5) concentration eliminated the differences in restitution of both APD and tension between S2 and S3. 6) BAY K 8644 (100 nM, n = 5) had no effect on this difference. CONCLUSIONS Greater variations of APD occur during the restitution of S3 than during S2 at short DIs. These differences appear to be caused by cyclic variations in tension and thus in [Ca2+]i. Calcium-sensitive outward currents could explain these differences in APD restitution.

The relation between ventricular late potentials and the occurrence of acute (in-hospital) and hyperacute (before hospital admission) ventricular tachycardia or fibrillation was studied in 281 consecutive patients with uninterrupted acute myocardial infarction. The prevalence of late potentials was significantly higher in patients with than without ventricular tachycardia/fibrillation (65 vs 22%; p less than 0.01). These relations persisted among patients with left bundle branch block, although a different definition was used for identifying late potentials in these patients. Multivariate analysis showed that presence of late potentials and peak creatine kinase enzyme level were the only 2 independent variables associated with early ventricular tachycardia/fibrillation. Total in-hospital mortality, as well as in-hospital cardiac mortality, was significantly higher among patients with than without acute ventricular tachycardia/fibrillation. However, at 1 year, mortality rates did not differ between the 2 groups. The following conclusions were drawn from this study: (1) Late potentials are closely related to ventricular tachycardia/fibrillation in hyperacute and acute phases of infarction. (2) Presence of left bundle branch block does not mitigate against the finding of late potentials in these patients. (3) Early ventricular tachycardia/fibrillation in acute infarction is related to large infarctions and to a high in-hospital mortality rate.

KARAGUEUZIAN, H.S., ET AL.: Nonhomogeneous Local Atrial Activity During Acute Atrial Fibrillation: Spectral and Dynamic Analysis. Atrial fibrillation (A Fib) has been categorized into four different types (I-IV) based on the morphology of the epicardial bipolar electrogram. In the present study, we hypothesized that these same types of A Fib also exist at endocardial sites. Simultaneous high, mid, and low right atrial endocardial bipolar electrograms were analyzed during acute A Fib induced by a rapid train of stimuli (20–40 Hz] for 1–3 seconds in anesthetized closed-chest dogs (N = 7, total of 72 episodes). A Fib lasted between 3 seconds and a few minutes (22.3 ± 22.8 sec). During A Fib, bipolar electrograms (0.5–500 Hz) were both discrete (types I and II) on electrograms recorded at one site and at the same time irregular (type III) on electrograms recorded at another site. The three simultaneously recorded electrograms encompassed all combinations of the four types of A Fib. When A Fib had a discrete electrogram morphology (types I andlor II), the mean rate of the A Fib was 494 ± 93 beats/min. At a given site, electrogram morphology also changed type over time. Fast Fourier transform (FFT) of the digitized electrograms (8–10 sec, 800 Hz digitization) showed peaks mostly below 15 Hz [range 0–30 Hz), that were either discrete (narrow band) with clear harmonic components, or had continuous (broad band) spectra, that changed in a time and site dependent manner. Phase plane plots (PPP), a plot of voltage versus rate of change of voltage, varied with respect to time and location. However, the morphology of these PPP often inscribed well defined structure suggesting dynamics compatible with deterministic chaos, rather than random dynamics. We conclude that A Fib is both temporally and spatially heterogeneous and that all combinations of the four different types of A Fib occur simultaneously. These findings may be helpful in developing robust algorithms for A Fib recognition for antitachycardia devices.

Objective: To determine how short and long term complication rates after pacemaker implantation are influenced by patient morbidity, operator experience, and choice of pacing system. Design: Retrospective analysis of 1884 patients who received VVI (n = 610), VDD (n = 371), or DDD devices (n = 903) between 1990 and 2001. Follow up period was 64 (34) months. The influence of age, sex, coronary artery disease, myocardial infarction, reduced left ventricular (LV) function, right ventricular (RV) dilatation, atrial fibrillation, device type, and operator experience on operation time and complication rate were analysed. Results: Operation time was prolonged in patients with coronary artery disease, inferior myocardial infarction, reduced LV function, and RV dilatation. Implantation of DDD pacemakers prolonged operation time, particularly among operators with a low or medium level of experience. The overall complication rate was 4.5%. Sixty seven per cent of these complications occurred within the first three months. Complication rate was increased by age, reduced LV function, and RV dilatation. Implantation of DDD systems led to a higher complication rate (6.3%) than implantation of VVI (2.6%) or VDD pacemakers (3.2%). These differences were present only among operators with a low or medium level of experience. Conclusions: Operation time and complication rate increased with age, impaired LV function, and RV dilatation. Complication rates were higher with DDD than with VVI or VDD implantation and were excessive among inexperienced but not experienced operators.

A higher incidence of pacemaker related complications has been reported in DDD systems as compared to VVI devices. The implantation of single lead VDD pacemakers might reduce the complication rate of physiological pacing in patients with AV block. In a retrospective study, the data records of 1,214 consecutive patients with pacemaker implantation for AV block between 1990 and 2001 (VVI 36.5%, DDD 32.9%, VDD 30.6%) were analyzed. Complications requiring surgical interventions were compared during a follow-up period of 64 ± 31 months. Operation and fluoroscopic times were longer in DDD pacemaker implantation compared to VDD and VVI devices:58 ± 23versus39 ± 10and37 ± 13 minutes (P < 0.001), 9.2 ± 5.2versus4.1 ± 2.4and3.5 ± 2.3 minutes, respectively. Differences remained significant after correction for covariates. In a multivariate Cox regression model, the corrected complication hazard of a DDD pacemaker implantation was increased by 3.9 (1.4–11.3) compared to VVI and increased by 2.3 (1.1–4.5) compared to VDD pacing. Higher complication rates in DDD pacing were mainly due to a higher incidence of early reoperation for atrial lead dysfunction, whereas the long-term complication rate was not different from VDD or VVI pacing. Early and long-term complication rates did not differ between VDD and VVI pacemaker systems. In conclusion, operation time and complication rates of physiological pacing are reduced by VDD pacemaker implantation achieving values comparable to VVI pacing. Thus, single lead VDD pacing can be recommended for patients with AV block. (PACE 2003; 26:1961–1969)

This article reports on a case of ventricular undersensing despite normal R wave amplitudes during sinus rhythm in an ICD patient. Undersensing of ventricular signals was noted without any evidence of lead dislocation or variation in signal amplitude. Undersensing was due to an exceptionally small R wave signal width and a feature of the Biotronik sensing algorithm designed to avoid oversensing. This algorithm, intended to enhance the sensing specifity of the device, requires registration of two consecutive points above the maximum programmed sensitivity for a ventricular sense event. After modifying the algorithm to a single point registration undersensing disappeared. (PACE 2003; 26:1776–1777)

This case report describes a patient with complete AV block and a VDD pacemaker who experienced repetitive episodes of symptomatic bradycardia. Episodes occurred due to activation of an automatic beat-to-beat mode switch algorithm. After mode switch to VDI operation, the pacemaker failed to immediately switch back to AV synchronous pacing when regular sinus rhythm (> or = 100 beats per minute) resumed despite adequate P wave sensing. Dizziness was felt for up to several minutes of asynchronous pacing at the lower rate limit until VDD mode was restored. Episodes were completely eliminated by programming the mode switch function from an automatic beat-to-beat algorithm to a fixed rate algorithm.

Aims Implantation of single-lead VDD pacemakers is an established alternative to DDD pacing in patients with atrioventricular block. This study compares the long-term costs of both systems. Methods and Results Three hundred and sixty patients with atrioventricular block received VDD or DDD pacemakers in alternating order. Primary costs of implantation included: devices, leads and operation material, surgeons, nurses, medical technicians, and hospitalization. The mean cost of an uncomplicated DDD pacemaker implantation was defined as 1000 virtual cost-units (CU). Costs of pacemaker related complications or re-operations as well as upgrades from VDD to DDD devices were considered secondary costs and assessed during a mean follow-up period of 42±15 months. Pacing efficacy was assessed by event-free survival with maintained atrioventricular synchronized pacing mode. Costs of pacemaker devices were not different (639±26CU in VDD vs 641±32CU in DDD, ns). However, due to lower costs of lead hardware (102±10CU in VDD vs 133±14CU in DDD, P

Steroid elution reduces the acute increase in stimulation threshold particularly in active fixation leads. The aim of this study was to investigate the long-term efficacy of steroid elution in atrial screw-in leads compared to conventional lead design. Two different bipolar active fixation platinum lead designs were implanted. Leads were similar except for the presence (group S, n = 66) or absence (group N, n = 68) of steroid elution. Patients received dual chamber pacemakers with the following atrial leads in consecutive order: Medtronic 4058 M (group N, n = 30), Medtronic 4068 (group S, n = 40), Vitatron IMS 13 (identical to 4058 M, group N, n = 38), and Vitatron IMX 13 (identical to 4068, group S, n = 26). The mean follow-up period was 40.7 +/- 16.1 months (range 10 to 84 months). Stimulation thresholds, pacing impedances, P wave potentials, and sensing threshold were assessed for both groups immediately, 10 days, 6 weeks, and 3 months after implantation followed by 6-months intervals. Energy thresholds, chronaxie-rheobase products, and energy consumption of atrial pacing were calculated. Chronic values were deduced from the most recent measurement performed in an individual patient. Within the first 10 days after implantation, atrial voltage threshold at pulse duration of 0.4 ms increased from 0.91 +/- 0.42 to 2.06 +/- 0.45 V in group N (P0.001). Less increase was observed in group S (0.83 +/- 0.39 to 1.08 +/- 0.53 V, P = 0.003). Atrial voltage thresholds remained markedly lower in steroid-eluting leads during whole follow-up (1.12 +/- 0.49 V in group S vs 1.58 +/- 0.71 V in group N, P0.001). Chronic energy consumption was markedly reduced in group S (4.0 +/- 2.7 microJ) compared to group N (9.8 +/- 7.5 microJ, P0.001). An atrial voltage threshold below 1.25 V at 0.4 ms was achieved in 92.3% of patients of group S allowing programming of an output of 2.5 V. Such low outputs were feasible in only 49.3% of patients in group N (P0.001). Chronic P wave amplitudes did not differ significantly between groups (3.27 +/- 1.81 mV in group N vs 3.24 +/- 1.18 mV in group S, P = 0.91). Steroid elution diminishes the increase of stimulation thresholds of nonsteroid atrial active fixation platinum leads resulting in a long-term reduction of energy consumption. Thus, use of steroids can be recommended for general use in atrial active fixation lead designs.

Implantation of single lead VDD pacemakers is an established therapeutic option in patients with AV block and normal sinus node function. However, related to occurrence of sinus node disease and atrial undersensing, there is concern whether VDD devices are appropriate in physically active young patients. Two hundred thirty-two consecutive patients with isolated AV block and VDD pacemakers were investigated. This population was subdivided into quartiles of 58 patients according to age at time of inclusion: 26.2-59.4 years (group A), 59.5-70.1 years (group B), 70.2-81.0 years (group C), and 81.1-92.5 years (group D). Follow-up visits included pacemaker telemetry, Holter monitoring, and exercise testing. Patients were visited at 2 and 12 weeks after implantation thereafter followed by 6-month intervals. Mean follow-up period was 35 +/- 14 months. Three months after implantation, atrial sensing threshold was significantly higher in young patients: 1.18 +/- 0.58 mV (group A) versus 0.79 +/- 0.35 mV (group B), 0.68 +/- 0.33 mV (group C), and 0.60 +/- 0.25 mV (group D), P < 0.001 for comparison of group A to all other groups. Atrial undersensing was observed less frequently in young patients: 6.9% (group A) versus 17.2% (group B), 24.1% (group C), and 27.6% (group D), P = 0.025 for intergroup comparisons. Sinus node dysfunction did not occur in group A. Atrial arrhythmias and loss of AV synchronized pacing mode occurred rarely in young patients: 0.6% (0.4%) per year in group A versus 1.3% (1.3%) in group B, 3.9% (3.4%) in group C, and 5.7% (7.4%) per year in group D, P < 0.01 for intergroup comparisons. Our data show good atrial sensing performance, low incidence of sinus node dysfunction, and few atrial arrhythmias in young patients with VDD pacing for AV block. Thus, single lead VDD pacing can be recommended particularly for young patients with AV block.

Background In patients with heart failure due to dilated cardiomyopathy, cardiac energy metabolism is impaired, as indicated by a reduction of the myocardial phosphocreatine-to-ATP ratio, measured noninvasively by 31 P-MR spectroscopy. The purpose of this study was to test whether the phosphocreatine-to-ATP ratio also offers prognostic information in terms of mortality prediction as well as how this index compares with well-known mortality predictors such as left ventricular ejection fraction (LVEF) or New York Heart Association (NYHA) class. Methods and Results Thirty-nine patients with dilated cardiomyopathy were followed up for 928±85 days (2.5 years). At study entry, LVEF and NYHA class were determined, and the cardiac phosphocreatine-to-ATP ratio was measured by localized 31 P-MR spectroscopy of the anterior myocardium. During the study period, total mortality was 26%. Patients were divided into two groups, one with a normal phosphocreatine-to-ATP ratio (>1.60; mean±SE, 1.98±0.07; n=19; healthy volunteers: 1.94±0.11, n=30) and one with a reduced phosphocreatine-to-ATP ratio (P =.036) and cardiovascular ( P =.016) mortality for patients with normal versus patients with low phosphocreatine-to-ATP ratios. A Cox model for multivariate analysis showed that the phosphocreatine-to-ATP ratio and NYHA class offered significant independent prognostic information on cardiovascular mortality. Conclusions The myocardial phosphocreatine-to-ATP ratio, measured noninvasively with 31 P-MR spectroscopy, is a predictor of both total and cardiovascular mortality in patients with dilated cardiomyopathy.

Die Bundesrepublik Deutschland hat sich in den vierzig Jahren ihres Bestehens von einem Staat, in dem „die Parteien an der Willensbildung des Volkes mitwirken“, zu einem politischen Gebilde entwickelt, in dem ohne Mitwirkung der Parteien oder gar gegen ihren Willen das Volk keine politische Bewegung von Belang ausfuhren kann. Man hat deshalb die Bundesrepublik Deutschland als einen Parteienstaat bezeichnet, ein Begriff, mit dem man die Vorstellung eines Staates verbindet, in dem die Parteien uber die enge politische Funktion als Identifikation- und Integrations-Medium politischer Stromungen hinaus alle Bereiche des offentlichen Lebens durchdringen. Sie machen nicht einmal an den Grenzen des offentlichen Lebens Halt, sondern wirken auch ins Privatleben hinein, wenn man denn nicht ohne Grund den Beruf zum Privatbereich zahlt. Viele Berufe in unserem Staat, vor allem, aber nicht ausschlieslich, im offentlichen Dienst, werden direkt oder heimlich von den Parteien verwaltet. In den Medien, einem Bereich im Grenzgebiet zwischen offentlichem und privaten Leben, sind die Parteien machtvoll vertreten. In der staatsburgerlichen Bildung auf allen Ebenen haben die Parteien zwar kein Monopol, aber geniesen heftige staatliche Privilegien fur ihre Institute, nicht zuletzt in Form von finanziellen Subventionen und Steuervergunstigungen. In den meisten halbstaatlichen Organisationen oder Korperschaften des Offentlichen Rechts, ob Gewerkschaften, Kassenarztliche Vereinigungen, Rundfunkrate, Beirate staatlicher oder halbstaatlicher Institutionen, sogar kirchlicher Organisationen sind die Parteien offiziell oder stillschweigend vertreten.

Mit dem Ende des Kalten Krieges, das wieder Raum fur heise Kriege schaffte, ist die Rolle und das Selbstverstandnis der Bundeswehr zum Problem geworden. Die Verfassungsbestimmungen, die den Einsatzbereich des deutschen Militars begrenzen, entwickeln eine ungeheure politische Brisanz, indem sie Deutschland vor aller Welt in die Position eines Ausenseiters drangen, der sich gemeinsamen Aktionen verbundeter oder gleichgesinnter Staaten entzieht. Handlungsfahigkeit und Glaubwurdigkeit der deutschen Politik sind durch diese ungeklarte Rolle des Militars schwer beeintrachtigt. Seit die Kuweit-Krise das Problem scharf und bewust gemacht hat, ist die Notwendigkeit einer verfassungsrechtlichen Klarung unbestritten. Um so heftiger umstritten ist allerdings das Wie.

Zweifellos haben die Wertvorstellungen „Mitte und Mas“ in unserer Zeit keine besondere Attraktion. Es geht kein Feuer, kein Motivationsschub von ihnen aus. Zweieinhalb Jahrtausende humanistischer und christlicher Mashalte-Philosophie scheinen sie ausgelaugt, um Energie und Substanz gebracht zu haben.

It can be expected that a structure which occurs as widely as the peritrophic membranes has several functions. The question is only which might be the primary and which might be additional functions. If the hypothesis is correct that peritrophic membranes are derived from the surface coat of the apical plasma membrane of midgut cells, it should have originally had properties of the surface coat, e.g. specific binding sites, like lectins (see Sect. 6.2) and glycoproteins, it might have been loaded with enzymes (see Sect. 6.3) and function as a permeability barrier (see Sect. 6.4). Reinforcement with chitin-containing microfibrils could have resulted in its use as protection against mechanical damage of the midgut epithelium by coarse particles of food and food residues (Schneider 1887) or by swelling of gut contents due to water uptake (Zhuzhikov 1964). Schneider’s opinion that peritrophic membranes are used to protect the midgut epithelium from abrasive food particles is mentioned in every textbook dealing with peritrophic membranes. It is obviously overestimated and mostly believed to be the only function. However, it cannot be denied that it is a valuable function. But the conclusion is wrong that peritrophic membranes are absent in fluid feeders because in these there is no need for such protection. Waterhouse (1953a) could show that many Lepidoptera and Diptera which feed on fluids nevertheless form peritrophic membranes (Table 4). In hematophagous insects hemoglobin-like crystals with sharp edges occur in the gut after a blood meal (Berner et al. 1983; Fig. 37, 38).

In most embryology papers nothing is said about the beginning of secretion of peritrophic membranes. Aubertot (1934) found these membranes already in immobile embryos in the brood pouch of water fleas, Daphnia pulex.