Efficacy and safety of zero-fluoroscopy ablation for supraventricular tachycardias. Use of optional contact force measurement for zero-fluoroscopy ablation in a clinical routine setting.

BACKGROUND: Conventional catheter ablation of cardiac arrhythmias is associated with radiation risks for patients and laboratory personnel. Widespread use of zero-fluoroscopic catheter ablation in clinical routine is limited by safety concerns. This study investigated the feasibility of zero-fluoroscopy catheter ablation using a three-dimensional mapping system and optional catheter contact force technology for an all-comers collective. PATIENTS AND METHODS: The study comprised 184 patients; 91 patients, including 29 pediatric patients, underwent a zero-fluoroscopic electrophysiology (EP) study using the EnSite NavX system with real-time visualization of all electrodes. These patients were matched to a control group, which was treated using fluoroscopy in the same period. Inclusion criteria were documented supraventricular tachycardia or a history of symptomatic paroxysmal supraventricular tachycardia. Transseptal access, if necessary, was achieved under transesophageal echocardiographic guidance for ablation of left-sided arrhythmias. Radiofrequency (using optional contact force measurement) or a cryotechnique was used for ablation. RESULTS: We observed no major acute complications. There were no significant differences between the two groups in the follow-up period. CONCLUSION: Zero-fluoroscopic catheter ablation is generally feasible in right-sided cardiac arrhythmias. Safety concerns regarding left atrial substrates or children can be overcome with optional real-time contact force measurement.

[Catheter ablation of paroxysmal atrial fibrillation: extended recommendations considering safety improvements of pulmonary vein isolation with a cryoballoon--Case 11/2011]. / Katheterablation von paroxysmalem Vorhofflimmern: großzügigere Indikationsstellung durch verbesserte Sicherheit der Pulmonalvenenisolation mittels Cryoballon - Fall 11/2011.

HISTORY AND ADMISSION FINDINGS: A 71-year-old, male patient was referred to our clinic for paroxysmal palpitations with dyspnoe and fatigue since four years despite pharmacological treatment with flecainide and bisoprolol. INVESTIGATIONS: A paroxysmal atrial fibrillation was documented in a 24-hour Holter recording. A bicycle ergometry showed a hypertensive reaction during exercise without any sign of coronary insufficiency. Intracardiac thrombi could by excluded by transesophageal echocardiography. DIAGNOSIS, TREATMENT AND COURSE: The diagnosos of a drug-refractory paroxysmal atrial fibrillation was made and cryoballoon pulmonary vein isolation was performed. A follow-up 3 months after the ablation disclosed a freedom from atrial fibrillation documented in 7-day Holter recording. CONCLUSIONS: Compared to pharmacological rhythm control, interventional treatment has been established as more effective therapy for paroxysmal atrial fibrillation. However, patients should be referred to the ablation early enough to avoid structural atrial remodeling and thus transition into persistent or permanent atrial fibrillation. New technical developments e.g. cryoballoon catheter-system simplifies the procedure and has been reported to be effective and safe to use for circumferential pulmonary vein isolation. Should the very promising preclinical data on efficacy and safety of cryothermal energy ablation be confirmed by results of ongoing, controlled trials, the catheter ablation may become the fist-line treatment for all patients with paroxysmal atrial fibrillation.

[Contact force control - the key to safe zero-fluoroscopy catheter ablation of atrioventricular nodal reentrant tachycardia]. / Die Anpresskraftkontrolle als Schlüssel zur sicheren strahlenfreien Katheterablation der AV-Knoten-Reentrytachykardie.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is a frequent supraventricular tachycardia in children and young adults. Despite favourable success rates of catheter ablation, conventional fluoroscopic catheter guidance is associated with risks of low-dose ionizing radiation for the patient and the personnel. Here we describe a technique for zero-fluoroscopy catheter ablation using contact force technology. PATIENTS AND METHODS: Zero-fluoroscopy catheter ablation was attempted in 12 patients with AVNRT (median age 20 years; range 11-75 years). An ablation catheter with integrated contact force sensor and a nonfluoroscopic electroanatomical mapping system was used for visualization of cardiovascular structures. Mean contact forces during mapping and ablation were restricted to an upper limit of 50 g to avoid cardiovascular injuries. RESULTS: Zero-fluoroscopy catheter ablation was performed successfully and uneventfully in all patients. There were no arrhythmia recurrences during a median follow-up of 6.2 months (range 2.7-12.8). CONCLUSION: Zero-fluoroscopy catheter ablation of AVNRT is possible and appears simple yet safe, when a nonfluoroscopic electroanatomical mapping system is used in combination with an ablation catheter with integrated contact force sensor. The presented technique could thus be easily employed in most electrophysiological laboratories.

Neonatal Marfan syndrome: unusually large deletion of exons 24-26 of FBN1 associated with poor prognosis.

Neonatal Marfan syndrome is a very rare subset of the classical Marfan syndrome with pronounced phenotypic expression especially of the cardiovascular manifestations. It is associated with a very poor prognosis, with approximately 50% of affected infants dying from cardiac failure during the first year of life. We present a newborn with the classical phenotype of neonatal Marfan syndrome. Within few hours after birth, progressive and refractory heart failure developed. Postmortal molecular study revealed an unusually large deletion of exons 24-26 within the so-called neonatal region of the gene FBN1, which might explain the unfavourable course of the disease in our patient.

Glycosylation and lectins-examples of immunesurveillance and immune evasion.

Cell surface proteins are posttranslationally modified by tightly regulated enzymes of glycosylation. Typical patterns of glycosylation may signal pathological situations to the immune system. Here, carbohydrate receptors on the surface of cells in the immune system are involved in regulation of effector cells. Moreover, some lectins are circulating in the plasma and take part in host defense. The code of carbohydrate modifications is impaired in malignant cells and yet they are not eliminated. In this review, we focus on recent experimental evidence for regulatory functions of lectins and carbohydrate derivatives in the immune system and tumours.

A large-scale method for T cell depletion: towards graft engineering of mobilized peripheral blood stem cells.

We have investigated the feasibility and efficacy of large-scale T cell depletion from granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSC). The method is based on the use of a CD3 antibody conjugated to magnetic microbeads and magnetic activated cell sorting (Clinimacs). A total of eight large-scale experiments were performed. In four experiments, CD3(+) T cells were depleted from PBSC obtained from volunteers mobilized with G-CSF whereas, in four experiments, T cells were depleted from PBSC from stem cell donors, in which the CD34(+) stem cells had been removed for allogeneic transplantation by positive selection prior to T cell depletion. The mean number of processed mononuclear cells (MNCs) was 3.3 x 10(10) (range 1.5 x 10(10)-5.1 x 10(10)) with a mean T cell proportion of 35.8% (range 16.7-64.0%). After T cell depletion, the percentage of contaminating T cells was 0.15% (range 0.01-1.01%) with a mean log(10) depletion of 3.4 (range 2.8-4.1). The mean recovery of CD3-negative MNCs after depletion was 76% (range 52-100%). The mean recovery of CD34(+) stem cells in the four evaluable experiments was 82% (range 75-92%). In vitro colony assays and in vivo NOD/SCID repopulation assays showed that this large-scale T cell depletion method has no negative impact on the function of the hematopoietic precursor cells. Therefore, we conclude that this T cell depletion method is a valuable tool for further graft engineering strategies involving mobilized PBSCs.

The oxidant thimerosal modulates gating behavior of KCNQ1 by interaction with the channel outer shell.

Thimerosal (o-Ethylmercurithio)benzoic acid, TMS), a membrane-impermeable, sulfhydryl-oxidizing agent, has been described to increase the K+ current IKs in KCNE1-injected Xenopus laevis oocytes. Since there are no cysteine residues in the extracellular domain of KCNE1, it has been proposed that TMS interacts with its partner protein KCNQ1. The aim of this study was therefore to investigate the interaction of TMS with KCNQ1 and the respective K+current IK. In CHO cells stably transfected with KCNQ1/KCNE1, TMS increased IKs, whereas in CHO cells expressing KCNQ1 alone, TMS initially decreased IK. TMS also affected the cytosolic pH (pHi) and the cytosolic Ca2+ activity ([Ca2+]i) in these cells. TMS slowly decreased pHi. With a short delay, TMS increased [Ca2+]i by store depletion and capacitative influx. The time course of the effects of TMS on pHi and [Ca2+]i did not correlate with the effect of TMS on IK. We therefore anticipated a different mode of action by TMS and investigated the influence of TMS on cysteine residues of KCNQ1. For this purpose, KCNQ1wt and two mutants lacking a cysteine residue in the S6 or the S3 segment (KCNQ1C331A and KCNQ1C214A, respectively) were expressed in Xenopus laevis oocytes. A sustained current decrease was observed in KCNQ1wt and KCNQ1C331A, but not in KCNQ1C214A-injected oocytes. The analysis of tail currents, I/V curves and activation kinetics revealed a complex effect of TMS on the gating of KCNQ1wt and KCNQ1C331A. In another series we investigated the effect of TMS on IKs. TMS increased IKs of KCNQ1C214A/KCNE1-injected oocytes significantly less than IKs in KCNQ1wt/KCNE1- or KCNQ1C331A/KCNE1-injected cells. These results suggest that thimerosal interacts with the cysteine residue C214 in the S3 segment of KCNQ1, leading to a change of its gating properties. Our results support the idea that not only the inner shell, but also the outer shell of the channel is important for the gating behavior of voltage dependent K+ channels.

Properties and function of KCNQ1 K+ channels isolated from the rectal gland of Squalus acanthias.

KCNQ1 (KVLQT1) K+ channels play an important role during electrolyte secretion in airways and colon. KCNQ1 was cloned recently from NaCl-secreting shark rectal glands. Here we study the properties and regulation of the cloned sKVLQT1 expressed in Xenopus oocytes and Chinese hamster ovary (CHO) cells and compare the results with those obtained from in vitro perfused rectal gland tubules (RGT). The expression of sKCNQ1 induced voltage-dependent, delayed activated K+ currents, which were augmented by an increase in intracellular cAMP and Ca2+. The chromanol derivatives 293B and 526B potently inhibited sKCNQ1 expressed in oocytes and CHO cells, but had little effect on RGT electrolyte transport. Short-circuit currents in RGT were activated by alkalinization and were decreased by acidification. In CHO cells an alkaline pH activated and an acidic pH inhibited 293B-sensitive KCNQ1 currents. Noise analysis of the cell-attached basolateral membrane of RGT indicated the presence of low-conductance (<3 pS) K+ channels, in parallel with other K+ channels. sKCNQ1 generated similar small-conductance K+ channels upon expression in CHO cells and Xenopus oocytes. The results suggest the presence of low-conductance KCNQ1 K+ channels in RGT, which are probably regulated by changes in intracellular cAMP, Ca2+ and pH.

Use of a myocutaneous flap after resection of a large lymphangioma.

UNLABELLED: We report on an 11-year-old girl with a large lymphangioma involving the lower third of the abdominal wall, the mons pubis, both labia majora, the perianal region and extending into the pelvic bones. Because of an increasing lymphorrhea from the cutaneous lesions resulting in considerable discomfort and skin infections, the patient sought medical advice. After lymphological check-up excluded the existence of a chylous reflux, the patient was presented at a multidisciplinary medical council. A palliative surgical treatment was recommended consisting of the resection of the most affected suprapubic region and the coverage of the resulting tissue defect with a gracilis myocutaneous flap. Postoperatively, a venous stasis at the tip of the skin paddle developed, which was relieved by the use of leeches and required secondary closure. Despite these complications, the surgical intervention yielded an acceptable cosmetic result, a diminution of lymphorrhea and hence subjectively some relief. CONCLUSION: Due to the variability of lymphangiomas, an assessment by a multidisciplinary consultation is proposed. With respect to therapy, the use of a myocutaneous flap represents one of the therapeutic options for large cutaneous lymphangiomas.

Inwardly rectifying K+ channels in the basolateral membrane of rat pancreatic acini.

Previous studies of the whole-cell K+ conductance suggest the presence of inwardly rectifying K+ channels (Kir) in rat pancreatic acini (RPAs). Here we investigate the properties of Kir of RPAs using patch-clamp techniques. The whole-cell current-to-voltage relationship of freshly isolated RPAs was steeper for inward currents than for outward currents when the extracellular K+ concentration ([K+]o) was raised. With a high [K+]o (145 mM), external application of Ba2+ and Cs+ blocked the inward K+ current in a voltage-dependent manner. The apparent IC50 of Ba2+ was 8.5+/-1.9 microM and 1.1+/-0.2 microM at -70 mV and -130 mV, respectively (n=5). The IC50 of Cs+ was 3.5+1.1 mM and 0.2+0.1 mM at -60 mV and -120 mV, respectively (n=4). Application of Ba2+ (0.1 mM) to the extracellular solution reversibly depolarized RPAs from -43+1.1 mV to -37+/-1.2 mV (n=20). In the cell-attached configuration with 145 mM KC1 in the pipette solution, we observed inwardly rectifying channels with a high open probability (PO) of 0.85+/-0.02 (n=6) and a slope conductance (Gs) of 30+/-2.8 pS (n=13). The same type of channel was observed in the outside-out patch. We could also observe a very small conductance K+ channel which was resistant to 0.1 mM Ba2+ and did not show inward rectification (n=11). RT-PCR analysis of RPA confirmed the presence of transcripts for Kir2.1, Kir2.3 and Kir7.1 subfamilies as molecular candidates for the observed channels. The above results demonstrate the presence of Kir channels in the basolateral membrane of the RPA, which may be important for the K+ recycling process during electrolyte secretion as well as for maintaining a hyperpolarized membrane.

KCNE1 reverses the response of the human K+ channel KCNQ1 to cytosolic pH changes and alters its pharmacology and sensitivity to temperature.

Previous studies have shown that heteromultimeric KCNQ1/KCNE1 (KvLQT1/minK) channels and homomultimeric KCNQ1 (KvLQT1) channels exhibit different current properties, e.g. distinct kinetics and different sensitivities to drugs. In this study we report on the divergent responses to internal pH changes and further characterize some of the current properties of the human isoforms of KCNQ1 and KCNE1 expressed in Chinese hamster ovary (CHO) cells or Xenopus laevis oocytes. Decreasing the bath temperature from 37 degrees C to 20 degrees C increased the half-activation time by a factor of 5 for KCNQ1/KCNE1 currents (IKs) but by only twofold (not significant) for KCNQ1 currents (IK) in CHO cells. Acidification of cytosolic pH (pHi) increased IKs but decreased 1K whereas intracellular alkalinization decreased I(Ks) but increased IK. pHi-induced changes in intracellular Ca2+ activity ([Ca2+]i) did not correlate with the current responses. At 20 degrees C mefenamic acid (0.1 mM) significantly augmented IKs but slightly decreased IK. It changed the slow activation kinetics of I(Ks) to an instantaneous onset. The form of the current/voltage (I/V) curve changed from sigmoidal to almost linear. In contrast, at 37 degrees C, mefenamic acid also increased I(Ks) but slowed the activation kinetics and shifted the voltage activation to more hyperpolarized values without markedly affecting the sigmoidal shape of the I/V curve. The potassium channel blockers clotrimazole and tetrapentylammonium (TPeA) inhibited I(Ks) with a lower potency than I(K). These results show that coexpression of KCNE1 reversed pH regulation of KCNQ1 from inhibition to activation by acidic pHi. In addition, KCNE1 altered the pharmacological properties and sensitivity to temperature of KCNQ1. The pH-dependence of I(Ks) might be of clinical and pathophysiological relevance in the pathogenesis of ischaemic cardiac arrhythmias.

Ca2+ influx induced by store release and cytosolic Ca2+ chelation in Ht29 colonic carcinoma cells.

Cl- secretion in HT29 cells is regulated by agonists such as carbachol, neurotensin and adenosine 5'-triphosphate (ATP). These agonists induce Ca2+ store release as well as Ca2+ influx from the extracellular space. The increase in cytosolic Ca2+ enhances the Cl- and K+ conductances of these cells. Removal of extracellular Ca2+ strongly attenuates the secretory response to the above-mentioned agonists. The present study utilises patch-clamp methods to characterise the Ca2+ influx pathway. Inhibitors which have been shown previously to inhibit non-selective cation channels, such as flufenamate (0.1 mmol.l-1, n = 6) and Gd3+ (10 micromol.l-1, n=6) inhibited ATP (0.1 mmol.l-1) induced increases in whole-cell conductance (Gm). When Cl- and K+ currents were inhibited by the presence of Cs2SO4 in the patch pipette and gluconate in the bath, ATP (0.1 mmol.l-1) still induced a significant increase in Gm from 1.2 +/- 0.3 nS to 4.7 +/- 1 nS (n = 24). This suggests that ATP induces a cation influx with a conductance of approximately 3-4 nS. This cation influx was inhibited by flufenamate (0.1 mmol.l-1, n = 6) and Gd3+ (10 micromol.l-1, n = 9). When Ba2+ (5 mmol.l-1) and 4,4'-diisothiocyanato-stilbene-2-2'-disulphonic acid (DIDS, 0.1 mmol.l-1) were added to the KCl/K-gluconate pipette solution to inhibit K+ and Cl- currents and the cells were clamped to depolarised voltages, ATP (0.1 mmol.l-1) reduced the membrane current (Im) significantly from 86 +/- 14 pA to 54 +/- 11 pA (n = 13), unmasking a cation inward current. In another series, the cation inward current was activated by dialysing the cell with a KCl/K-gluconate solution containing 5-10 mmol.l-1 1,2-bis-(2-aminoethoxy)ethane-N,N,N',N'-tetraacetic acid (EGTA) or 1,2-bis-(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA). The zero-current membrane voltage (Vm) and Im (at a clamp voltage of +10 mV) were monitored as a function of time. A new steady-state was reached 30-120 s after membrane rupture. Vm depolarised significantly from -33 +/- 2 mV to -12 +/- 1 mV, and Im fell significantly from 17 +/- 2 pA to 8.9 +/- 1.0 pA (n = 71). This negative current, representing a cation inward current, was activated when Ca2+ stores were emptied and was reduced significantly ( Im) when Ca2+ and/or Na+ were removed from the bathing solution: removal of Ca2+ in the absence of Na+ caused a Im of 5.0 +/- 1.2 pA (n = 12); removal of Na+ in the absence of Ca2+ caused a Im of 12.8 +/- 3.5 pA (n = 4). The cation inward current was also reduced significantly by La3+, Gd3+, and flufenamate. We conclude that store depletion induces a Ca2+/Na+ influx current in these cells. With 145 mmol.l-1 Na+ and 1 mmol.l-1 Ca2+, both ions contribute to this cation inward current. This current is an important component in the agonist-regulated secretory response.