Characteristics of Perforin Expressing Lymphocytes Within the First Trimester Decidua of Human Pregnancy

PROBLEM : The number of perforin (P)-positive cells in decidua of pregnancy is larger than that observed in any other pathological condition. The aim was to investigate the distribution and the phenotype of P⁺ cells. METHOD : Decidual tissue was obtained from the first trimester vaginal termination of pregnancy. Tissue distribution of P⁺ cells was analyzed by immunohistochemistry. The method for simultaneous measurement of P and cell surface is presented. RESULTS : There is no difference in number and distribution of P⁺ cells between decidua basalis (DB) and decidua parietalis (DP). The percentage of P⁺ decidual lymphocytes (DL) is two times higher than in peripheral blood lymphocytes (PBL) (55% vs. 27%), and the prevalent phenotype is CD3^? CD4^? CD8^? CD2⁺ (95%) CD11c⁺ (68%) and CD56⁺ (82%). CD56^bright+ DL are also P^bright+ and this is the largest DL subpopulation (42.4% DL). Two different subpopulations of CD8⁺ DL exist: 1) CD8^bright+, which are CD3⁺ CD56^? P^? and 2) CD8^dim+, which are CD3^? CD56⁺ P⁺. CONCLUSION : P expressing DL are prevalently nonclassical NK cells (CD16^?) with low cytolytic activity but fully equipped with potent cytolytic machinery (p^bright+). There are no classical cytotoxic lymphocytes (CTL) (CD3⁺ CD8⁺ P⁺) in the decidua, and all CD8⁺ P⁺ cells are CD3^? CD56⁺. The number of P⁺ cells is even higher in DP in the vicinity of noninvasvie trophoblast, than in DB.     

Temperature-controlled Rate Responsive Pacing with the Aid of an Optimized Algorithm

On the basis of earlier studies of the behavior of the central venous blood temperature at rest and during exercise, we have developed an algorithm for the rate control of cardiac pacemakers. The central venous blood temperature serves as the control variable for the pacing rate. Control is effected via two different characteristic lines that relate pacing rate and temperature. A rest characteristic line relates absolute temperature values to heart rate and exercise lines relate relative changes in temperature to heart rate changes. The rest characteristic corresponds to conditions of slow temperature fluctations (e.g., fever and temperature changes due to circardian rhythm) and has a slope of 15 to 20 bpm per centigrade degree of temperature change. Starting at this rest characteristic, there are exercise characteristic lines that have a much greater slope and serve to regulate the pacing rate under exercise conditions. The two characteristics are distinguished via the temperature change per unit of time. In addition, a return characteristic connects the rest and exercise characteristics. This algorithm allows for optimized rate adaption of physiological cardiac pacemakers by central venous blood temperature. Clinical studies with the implanted device (Intermedics Nova MR) prove the correct function and beneficial effect of this algorithm in patients' everyday life.     

Behavior of Different Activity-Based Pacemakers During Treadmill Exercise Testing with Variable Slopes: A Comparison of Three Activity-Based Pacing Systems

A new generation of activity-based pacemakers incorporates an accelerometer sensitive to low frequency acceleration signals in the anteroposterior direction for sensing of bodily stress. The purpose of our investigation was to test a representative model of these new activity-based pacemakers (Relay) and compare it with current vibrationand housing pressure-sensing systems. We tested ten pacemaker patients with implanted Activitrax, Sensolog, and Relay systems during treadmill exercise testing with variable slopes. Devices from the three systems were also strapped externally to the chest of each patient and to ten normal test subjects in the control group. Exercise tests were conducted with changes of treadmill speed and/or treadmill slope. For comparable workloads during constant speed/variable slope and constant slope/variable speed, Relay had similar rate responses (difference not significant). Significant differences (P < 0.05) in rate adaptation attributable to the kind of treadmill exercise (change in treadmill speed or slopes) were observed in the housing pressure- and vibration-based pacemakers. Activity-based pacemakers with an acceleration sensor adapt pacing rates during treadmill exercises independent of treadmill speed or slope better than those controlled by a conventional housing pressure or vibration sensor.     

New ICD-Technologies: First Clinical Experience with Dual-Chamber Sensing for Differentiation of Supraventricular Tachyarrhythmias

Inappropriate ICD therapy for supraventricular arrhythmias remains an unsolved problem and may lead to serious clinical situations. Current algorithms for differentiation of supraventricular and ventricular arrhythmias are based on ventricular sensing solely and, therefore, lack semitivity and specificity. This preliminary analysis from a multicenter trial comprises data from the first 26 patients who received a Res-Q? Micron active-can ICD (Stdzer Intermedics) with a ventricular defibrillation lead and an additional bipolar lead for atrial sensing. Digitized atrial and ventricular waveform storage as well as interval charts from 102 induced and 30 spontaneous arrhythmia episodes were prospectively collected and analyzed with regard to appropriateness of ICD therapy. From all 132 arrhythmia episodes, high-quality stored dual-chamber intracardiac electrograms (JFXJM) could be retrieved for further analysis: in 40 (30%) episodes, atrial fibrillation (AF with rapid ventricular response 22, AF with VT9, AF with VF 9) was identified as the underlying intrinsic rhythm, and inappropriate ICD therapy was delivered in 4/22 (18%) episodes of AF with rapid ventricular response. In the remaining 92 (70%) episodes, sinus rhythm was the underlying atrial rhythm (SR with VT 13, SR with VF 79), and no inappropriate therapy was observed. Three of 22 (15%) high-energy shocks delivered for ventricular arrhythmias (VT 9, VF 9, rapid AF 4) terminated AF at the same time. In total, there were 3 complications (2 atrial lead dislodgments, I revision for bleeding). Both atrial lead dislodgments occurred in the 2 patients with passive-fixation leads compared to none in the 24 patients with active-fixation leads (p - 0.003). In conclusion, dual-chamber sensing and waveform storage of the new Res-Q? Micron offer very helpful diagnostic tools for the detection of inappropriate ICD-therapy. Placement of an additional atrial lead is safe and does not interfere with proper ICD function. However, for avoidance of atrial lead dislodgment, active fixation leads are recommended With the tested active-can lead configuration, the efficacy of successful atrial cardioversion by high-energy shocks delivered for ventricular arrhythmias seems to be low.     

Three-Year Experience with a Stylet for Lead Extraction: A Multicenter Study

The extraction of chronically implanted and infected pacemaker and defibrillator leads is an important issue. This article describes the experience gathered between 1990 and 1994 by seven European centers regarding a locking stylet that is uniformly applicable for a wide variety of internal pacing coil diameters. This interventional locking stylet for lead extraction has an outer diameter of 0.4 mm (0.016 inches). The stylet consists of a hollow shaft in which an inner traction wire is embedded. At the tip of the inner traction wire an anchoring mechanism, which can be opened by retraction, is applied. Removal attempts were made for 150 leads, 110 in ventricular and 40 in atrial positions. Results : Complete removal was possible in 122 cases (81 %). Partial removal was possible in 18 cases (12%). Failure to remove the lead with the extraction stylet was experienced in 10 cases (7%). In seven patients, the leads were removed by cardiothoracic surgery; 3 defective leads were left in place. There were no serious complications associated with the procedure. None of the patients died. Conclusion : The experience with this extraction stylet for lead removal has shown good results. Despite a low complication rate thus far, each case for lead removal should be judged on the individual basis of benefit-to-risk ratio.