Emergency Placement of Platinum Coils to Prevent Cardiac Tamponade After Wire Perforation of an Occluded Venous Coronary Bypass Graft

A case is reported of a patient with impending cardiac tamponade due to vessel perforation following balloon angioplasty of an occluded venous bypass graft. Prolonged balloon inflation failed to seal the perforation. Leakage was controlled immediately by the delivery of two platinum coils into the perforation. In case of a vessel perforation during an attempt to recanalize an occluded coronary artery bypass, placement of intracoronary platinum coils to seal the perforation may prevent the development of cardiac tamponade.     

Extensive Variation in the Signal Amplitude of the Atrial Floating VDD Pacing Electrode

The dependence of atrial signal amplitude on the site of the ntrial sensing dipole of a single-pass lead was examined in 29 patients. The vertical location of the dipole was documented in supine fluo-roscopy during quiescent and deep breathing and in upright chest roentgenogram, and was expressed as a proportion of the, right atrial height. As the group average, the atrial signal amplitude was equal when tested in supine, sitting, standing, and right- or left-side positions in follow-up determinations. The signal amplitude varied markedly between postures, showing a coefficient of variation of 45%± 24% within the group. Coefficient of variation within the 6-month fallow-up period in each tested position ranged from 31%−4 4%, Correlation between postures was weak (range of r = 0.53–0.81). Vertical location of the atrial dipole had no relationship to the signal amplitude. At least in one posture or test occasion the atrial signal amplitude was very low, ≤ 0.35 mV in 20 patients, and below detection limit (0.25 mV) in 5 patients. Programmed to high sensitivity, atrial undersensing was rare in ambulatory electrocardiography, ranging from 0–9,000 missed atrial beats (0%–8%), with a median of 100 beats/24 hours. In conclusion, temporary variation in atrial signal amplitude is extensive. Despite occasionally measured large signal amplitudes atrial sensitivity in single lead VDD pacemakers should be programmed high, and if poor atrial tracking is suspected, other methods besides routine sensitivity testing should be adapted.     

Examination of Explanted Polyurethane Pacemaker Leads Using the Scanning Electron Microscope

Since 1978, 2,365 polyurethane (PU) insulated cardiac pacing leads were implanted transvenously at our institution. To date, there have been no insulation failures in those leads. Thirty-seven PU leads were explanted, mainly for exit block, and 28 of these were investigated using the scanning electron microscope. We found a homogeneous distribution of surface changes in all lead segments in 56% of the 28 examined. These changes were more pronounced at the ligature site; severe surface cracking was noticed in 21%, with the deepest crack being 40 micron (average range of 10-15 micron). There appeared to be no time-dependency of the surface changes as indicated by regression analysis (r = 0.32, p greater than 0.05). The ultimate severity and outcome of this degradation process in the leads reported in this study will only be known in the future after longer use. We conclude that excess stress must be avoided during the implantation procedure and that careful surveillance is necessary.     

Mechanical Wear of Pacemaker Lead Insulation. A Cause of Loss of Pacing

A pacemaker-treated patient is described in whom lead insulation defect caused sudden loss of capture. The defect was caused by mechanical wear of the posterior leaflet of the tricuspid valve and resulted in shunting of the pulse generator with a current drain exceeding the capacity of the pacemaker. In three further cases a similar explanation to sudden loss of pacing was highly suspected.     

Murine Stress-triggered Abortion is Mediated by Increase of CD8+ TNF-α+ Decidual Cells via Substance P

PROBLEM: Stress is known to induce abortions in mice and humans. Increased levels of abortogenic type 1 helper T-cell cytokines and decreased levels of pregnancy protective cytokines could be linked to stress-triggered embryonic loss. Stress promotes neurotransmitter substance P (SP) release in tissues. SP increases the production of decidual tumor necrosis factor (TNF)-alpha, whereby the phenotype of these TNF-alpha-producing cells is hypothetical. The objective of the present study was to identify decidual TNF-alpha-producing cell populations that are involved in stress-induced murine abortion. METHOD: DBA/2J-mated CBA/J female mice were exposed to ultrasonic sound stress on day 5.5 of pregnancy. The mice were randomized and half were treated with the SP NK1-receptor antagonist (SP-RA) RP 67580 (200 microg/mouse). Frequency and cytokine profile of CD8+ cells were evaluated by immunohistochemistry and flow cytometry. Degranulation of uterine mast cells was examined histologically. RESULTS: On day 13.5 of pregnancy, the uteri were removed and the resorption rate was calculated. A mean resorption rate of 38.4% was detected in stressed mice (n = 10) compared to 13.1% in non-stressed control mice (n = 11, P < 0.01). Injection of SP-RA decreased the abortion rate to 18.4% in stressed mice (n = 19, P < 0.01). Flow cytometry revealed a stress-related increase of TNF-alpha+/CD8+ decidual T cells, which could be abrogated by SP-RA (P < 0.05). No significant differences could be observed in numbers of mast cells and total CD8+ cells in situ. CONCLUSION: Our data suggest that stress-triggered abortion is mediated by SP, and SP receptor blockade abrogates stress-triggered abortion via reduced production of TNF-alpha by CD8+ T cells.     

Fat Content and Fatty Acid Composition of Infant Formulas

ABSTRACT. Fat content and fatty acid composition of 25 commercial infant formulas sold in the Federal Republic of Germany and of 3 home-made milk formulas were analysed, using gravimetry of extracted lipids and high-resolution capillary gaschromatography. Results were compared with the composition of human milk. Fat contents of all commercial formulas were similar to human milk values and met current recommendations, but 2 home-made preparations were at the upper and lower limits of the recommended range. Milk formulas tended to contain higher percentages of saturated and lower ones of cis-monounsaturated and trans-isomeric fatty acids than human milk. Linoleic acid (C18:2n-6) content was similar to human milk in most products but deviated clearly from recommended values in 2 home-made mixtures. Alpha-linolenic acid (C18:3n-3) values were often low in formulas, resulting a high n-6/n-3-ratios. In contrast to human milk, all formulas contained only minor amounts of the physiologically important long-chain polyunsaturated fatty acids with 20 and 22 carbon atoms. Some seasonal variation in the content of palmitic (C16:0), oleic (C18:ln-9), linoleic and trans-fatty acids was found when five arbitrarily selected adapted formulas were analysed repeatedly over one year. The composition of a home-made formula made from fresh cow's milk was markedly different in winter and in summer, when percentages of saturated and trans-fatty acids were higher and of linoleic acid were lower. We conclude that the composition of most commercial formulas is better suited to meet the lipid requirements of young infants than the home-made preparations investigated. However, the essential fatty acid composition of available milk formulas differs from that of human milk.     

Defibrillation Energy Requirements with Single Endocardial (Endotak™) Lead

The need for thoracotomy in usually high risk patients has limited the use of the implantable cardioverter defibrillator. Initial clinical results with endocardial and subcutanous patch electrodes (SQPs) are en couraging. Using a single endocardial lead in the absence of a SQP for chronic implantation of the cardioverter defibrillator, the goal of the study was to obtain defibrillation thresholds (DFTs) of 15 Joules (J) or less and to investigate changes in DFT over time. We tested 19 consecutive patients (15 men, 4 women] age 62 ± 8.5 years with malignant ventricular arrhythmias (14 VT/5 VF). The underlying heart disease was coronary artery disease in 15 pafients, dilative cardiomyopathy in two patients, and primary electricaJ disease in two patients. Four patients had undergone previous cardiac surgery. Left ventricular ejection fraction ranged between 14% and 66% (39%± 12.6%). Pacing thresholds (0.54 ± 0.17 Vat 0.5 msec), R wave amplitude for pacemaker sensing (14.2 ± 7.0 mV), slew rate (2.12 ± 1.4 V/sec), and resistance (500.3 ± 73.9 W) were sufficient in all patients. Eighteen patients met our endocardial impiant criteria with a DFT ≤ 15 J (10.05 ± 4.03 J) using monophasic (14 patients) or biphasic (four patients) pulse wave forms. In the one remaining patient, with a DFT of 20 J, we implanted a SQP but there was no reduction of the DFT. All patients tested showed successful defibrillation prior to discharge. During follow-up of 88 patient-months (1–9 months), 114 spontaneous VT/VF episodes occurred in five patients and were all successfully terminated. Eleven patients with a minimum follow-up of 2 months were reassessed. In seven out of 11 patients, termination of VF was achieved with the same minimal energy requirements obtained intraoperatively. In three patients, DFT increased by 5 J (one patient) and 10 J (two patients). In a further patient, X ray revealed dislocation of the endocardial lead. Our data suggest that effective defibrillation is feasible with a single endocardial lead for implantation of cardioverter defibrillator. In addition, we strongly recommend repetitive x-ray control to detect asymptomatic lead dislocation. Despite stable DFTs in most of our patients, an energy difference of ≤ 15 J between acute DFT and cardioverter defibrillator energy rating seems to be currently desirable to ensure successful postoperative defibrillation.     

Cyclic disulfide analogues of the complement component C3a Synthesis and conformational investigations

The flexible C-terminal region of the anaphylatoxic peptide C3a was reported to contain the receptor binding site. To elucidate the receptor binding conformation of the C-terminus, as well as to examine a synthetic approach to potential C3a-antagonists, 26 cyclic disulfide bridged C3a analogues were synthesized. Solid phase peptide synthesis was performed on different polymeric supports by individual peptide synthesis, with Fmoc strategy, and simultaneous multiple peptide synthesis, using Boc and Fmoc strategies. Both strategies gave open-chain peptides in comparable yields. Syntheses using the Boc strategy employed the HF-labile 4(methoxy)benzyl group (Mob) for β-thiol protection of cysteine; in contrast, the TFA-stable protecting groups, acetamidomethyl (Acm) and trityl (Trt), were chosen for syntheses employing Fmoc strategy. Ring closure reactions by iodine oxidation were carried out starting from protected (Acm/Acm, Trt/Acm) or unprotected dithiols. The resulting cyclic C3a analogues were characterized by HPLC, amino acid analysis, and FAB-MS. Conformational investigations using CD spectroscopy and theoretical structural investigations by means of molecular dynamics calculations revealed that slight variations in sequence result in pronounced conformational consequences. The potential of cyclic C3a analogues to activate or to desensitize guinea pig platelets, a standard test system for biological activities of anaphylatoxic peptides like C3a, revealed relatively low activities for cyclic peptides (<0.1% C3a activity). N-terminal acylation with cationic, arginine-rich sequences like YRRGR- led to amplified biological effects. Three of the synthesized peptides, namely CAALCLAR (P1), YRRGR°CGGLCLAR (P5) and YRRGRAhx°CGGLCLAR (P8), point in the direction of C3a antagonists.