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Aims: Uncertainty exists over the importance of device-detected short-duration atrial arrhythmias. Continuous atrial diagnostics, through home monitoring (HM) technology (BIOTRONIK, Berlin, Germany), provides a unique opportunity to assess frequency and quantity of atrial fibrillation (AF) episodes defined as atrial high-rate events (AHRE).Methods and Results: Prospective data from 560 heart failure (HF) patients (age 67 ± 10 years, median ejection fraction 27%) patients with a cardiac resynchronization therapy (CRT) device capable of HM from two multi-centre studies were analysed. Atrial high-rate events burden was defined as the duration of mode switch in a 24-h period with atrial rates of >180 beats for at least 1% or total of 14 min per day. The primary endpoint was incidence of a thromboembolic (TE) event. Secondary endpoints were cardiovascular death, hospitalization because of AF, or worsening HF. Over a median 370-day follow-up AHRE occurred in 40% of patients with 11 (2%) patients developing TE complications and mortality rate of 4.3% (24 deaths, 16 with cardiovascular aetiology). Compared with patients without detected AHRE, patients with detected AHRE>3.8 h over a day were nine times more likely to develop TE complications (P= 0.006). The majority of patients (73%) did not show a temporal association with the detected atrial episode and their adverse event, with a mean interval of 46.7 ± 71.9 days (range 0-194) before the TE complication.Conclusion: In a high-risk cohort of HF patients, device-detected atrial arrhythmias are associated with an increased incidence of TE events. A cut-off point of 3.8 h over 24 h was associated with significant increase in the event rate. Routine assessment of AHRE should be considered with other data when assessing stroke risk and considering anti-coagulation initiation and should also prompt the optimization of cardioprotective HF therapy in CRT patients. [ABSTRACT FROM AUTHOR]

Aims: Current European Society of Cardiology guidelines state that repetitive monitoring and feedback should be implemented for ST-elevation myocardial infarction (STEMI) treatment, but no evidence is available supporting this recommendation. We aimed to analyze the long-term effects of a formalized data assessment and systematic feedback on performance and mortality within the prospective, multicenter Feedback Intervention and Treatment Times in STEMI (FITT-STEMI) study., Methods: Regular interactive feedback sessions with local STEMI management teams were performed at six participating German percutaneous coronary intervention (PCI) centers over a 10-year period starting from October 2007., Results: From the first to the 10th year of study participation, all predefined key-quality indicators for performance measurement used for feedback improved significantly in all 4926 consecutive PCI-treated patients - namely, the percentages of patients with pre-hospital electrocardiogram (ECG) recordings (83.3% vs 97.1%, p < 0.0001) and ECG recordings within 10 minutes after first medical contact (41.7% vs 63.8%, p < 0.0001), pre-announcement by telephone (77.0% vs 85.4%, p = 0.0007), direct transfer to the catheterization laboratory bypassing the emergency department (29.4% vs 64.2%, p < 0.0001), and contact-to-balloon times of less than 90 minutes (37.2% vs 53.7%, p < 0.0001). Moreover, this feedback-related continuous improvement of key-quality indicators was linked to a significant reduction in in-hospital mortality from 10.8% to 6.8% ( p = 0.0244). Logistic regression models confirmed an independent beneficial effect of duration of study participation on hospital mortality (odds ratio = 0.986, 95% confidence interval = 0.976-0.996, p = 0.0087). In contrast, data from a nationwide PCI registry showed a continuous increase in in-hospital mortality in all PCI-treated STEMI patients in Germany from 2008 to 2015 ( n = 398,027; 6.7% to 9.2%, p < 0.0001)., Conclusions: Our results indicate that systematic data assessment and regular feedback is a feasible long-term strategy and may be linked to improved performance and a reduction in mortality in STEMI management., (© The European Society of Cardiology 2020.)

We report novel supramolecular polymers, which possess a reversed viscosity/temperature profile. To this end, we developed a series of ditopic monomers featuring two self-complementary binding sites, either the guanidiniocarbonyl pyrrole carboxylic acid (GCP) or the aminopyridine carbonyl pyrrole carboxylic acid (ACP). At low temperatures, small cyclic structures are formed. However, at elevated temperatures, a ring-chain transformation leads to the formation of a supramolecular polymer. We demonstrate that this effect is dependent on the concentration of the solution and on the polarity of the solvent. This effect can counteract the loss of viscosity of the solvent at elevated temperatures, thus opening an application of our systems as viscosity index improvers (VIIs) in working fluids. This was tested for different motor oils and led to the identification of one compound as a promising VII., (Copyright © 2021, Ostwaldt et al.; licensee Beilstein-Institut.)

Background: In ST-segment elevation myocardial infarction (STEMI) patients treated with percutaneous coronary intervention, direct transport from the scene to the catheterisation laboratory bypassing the emergency department has been shown to shorten times to reperfusion. The aim of this study was to investigate the effects of emergency department bypass on mortality in both haemodynamically stable and unstable STEMI patients., Methods: The analysis is based on a large cohort of STEMI patients prospectively included in the German multicentre Feedback Intervention and Treatment Times in ST-Elevation Myocardial Infarction (FITT-STEMI) trial., Results: Out of 13,219 STEMI patients who were brought directly from the scene by emergency medical service transportation and were treated with percutaneous coronary intervention, the majority were transported directly to the catheterisation laboratory bypassing the emergency department ( n =6740, 51% with emergency department bypass). These patients had a significantly lower in-hospital mortality than their counterparts with no emergency department bypass (6.2% vs. 10.0%, P <0.0001). The reduced mortality related to emergency department bypass was observed in both stable ( n =11,594, 2.8% vs. 3.8%, P =0.0024) and unstable patients presenting with cardiogenic shock ( n =1625, 36.3% vs. 46.2%, P <0.0001). Regression models adjusted for the Thrombolysis In Myocardial Infarction (TIMI) risk score consistently confirmed a significant and independent predictive effect of emergency department bypass on survival in the total study population (odds ratio 0.64, 95% confidence interval 0.56-0.74, P <0.0001) and in the subgroup of shock patients (OR 0.69, 95% CI 0.54-0.88, P =0.0028)., Conclusion: In STEMI patients, emergency department bypass is associated with a significant reduction in mortality, which is most pronounced in patients presenting with cardiogenic shock. Our data encourage treatment protocols for emergency department bypass to improve the survival of both haemodynamically stable patients and, in particular, unstable patients. Clinical Trial Registration: NCT00794001 ClinicalTrials.gov: NCT00794001.

Patients with genetic cardiomyopathy that involves myocardial hypertrophy often develop clinically relevant arrhythmias that increase the risk of sudden death. Consequently, guidelines for medical device therapy were established for hypertrophic cardiomyopathy, but not for conditions with only anecdotal evidence of arrhythmias, like Fabry cardiomyopathy. Patients with Fabry cardiomyopathy progressively develop myocardial fibrosis, and sudden cardiac death occurs regularly. Because 24-hour Holter electrocardiograms (ECGs) might not detect clinically important arrhythmias, we tested an implanted loop recorder for continuous heart rhythm surveillance and determined its impact on therapy. This prospective study included 16 patients (12 men) with advanced Fabry cardiomyopathy, relevant hypertrophy, and replacement fibrosis in "loco typico." No patients previously exhibited clinically relevant arrhythmias on Holter ECGs. Patients received an implantable loop recorder and were prospectively followed with telemedicine for a median of 1.2 years (range 0.3 to 2.0 years). The primary end point was a clinically meaningful event, which required a therapy change, captured with the loop recorder. Patients submitted data regularly (14 ± 11 times per month). During follow-up, 21 events were detected (including 4 asystole, i.e., ECG pauses ≥3 seconds) and 7 bradycardia events; 5 episodes of intermittent atrial fibrillation (>3 minutes) and 5 episodes of ventricular tachycardia (3 sustained and 2 nonsustained). Subsequently, as defined in the primary end point, 15 events leaded to a change of therapy. These patients required therapy with a pacemaker or cardioverter-defibrillator implantation and/or anticoagulation therapy for atrial fibrillation. In conclusion, clinically relevant arrhythmias that require further device and/or medical therapy are often missed with Holter ECGs in patients with advanced stage Fabry cardiomyopathy, but they can be detected by telemonitoring with an implantable loop recorder., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Macrocycles with quaterthiophene subunits were obtained by cyclooligomerization by direct oxidative coupling of unsubstituted dithiophene moieties. The rings were closed with high selectivity by an α,β'-connection of the thiophenes as proven by NMR spectroscopy. The reaction of the precursor with terthiophene moieties yielded the symmetric α,α'-linked macrocycle in low yield together with various differently connected isomers. Blocking of the β-position of the half-rings yielded selectively the α,α'-linked macrocycle. Selected cyclothiophenes were investigated by scanning tunneling microscopy, which displayed the formation of highly ordered 2D crystalline monolayers., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An essential and so far unresolved factor influencing the evolution of cancer and the clinical management of patients is intratumour clonal and phenotypic heterogeneity. However, the de novo identification of tumour subpopulations is so far both a challenging and an unresolved task. Here we present the first systematic approach for the de novo discovery of clinically detrimental molecular tumour subpopulations. In this proof-of-principle study, spatially resolved, tumour-specific mass spectra were acquired, using matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry, from tissues of 63 gastric carcinoma and 32 breast carcinoma patients. The mass spectra, representing the proteomic heterogeneity within tumour areas, were grouped by a corroborated statistical clustering algorithm in order to obtain segmentation maps of molecularly distinct regions. These regions were presumed to represent different phenotypic tumour subpopulations. This was confirmed by linking the presence of these tumour subpopulations to the patients' clinical data. This revealed several of the detected tumour subpopulations to be associated with a different overall survival of the gastric cancer patients (p = 0.025) and the presence of locoregional metastases in patients with breast cancer (p = 0.036). The procedure presented is generic and opens novel options in cancer research, as it reveals microscopically indistinct tumour subpopulations that have an adverse impact on clinical outcome. This enables their further molecular characterization for deeper insights into the biological processes of cancer, which may finally lead to new targeted therapies., (Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

One of the limiting factors in determining the sensitivity of tandem mass spectrometry using hybrid quadrupole orthogonal acceleration time-of-flight instruments is the duty cycle of the orthogonal ion injection system. As a consequence, only a fraction of the generated fragment ion beam is collected by the time-of-flight analyzer. Here we describe a method utilizing postfragmentation ion mobility spectrometry of peptide fragment ions in conjunction with mobility time synchronized orthogonal ion injection leading to a substantially improved duty cycle and a concomitant improvement in sensitivity of up to 10-fold for bottom-up proteomic experiments. This enabled the identification of 7500 human proteins within 1 day and 8600 phosphorylation sites within 5 h of LC-MS/MS time. The method also proved powerful for multiplexed quantification experiments using tandem mass tags exemplified by the chemoproteomic interaction analysis of histone deacetylases with Trichostatin A., (© 2014 by The American Society for Biochemistry and Molecular Biology, Inc.)

Mass spectrometers equipped with matrix-assisted laser desorption/ionization (MALDI-MS) require frequent multipoint calibration to obtain good mass accuracy over a wide mass range and across large numbers of samples. In this study, we introduce a new synthetic peptide mass calibration standard termed PAS-cal tailored for MALDI-MS based bottom-up proteomics. This standard consists of 30 peptides between 8 and 37 amino acids long and each constructed to contain repetitive sequences of Pro, Ala and Ser as well as one C-terminal arginine residue. MALDI spectra thus cover a mass range between 750 and 3200 m/z in MS mode and between 100 and 3200 m/z in MS/MS mode. Our results show that multipoint calibration of MS spectra using PAS-cal peptides compares well to current commercial reagents for protein identification by PMF. Calibration of tandem mass spectra from LC-MALDI experiments using the longest peptide, PAS-cal37, resulted in smaller fragment ion mass errors, more matching fragment ions and more protein and peptide identifications compared to commercial standards, making the PAS-cal standard generically useful for bottom-up proteomics., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Voltage-gated sodium channels are responsible for the rising phase of the action potential in cardiac muscle. Previously, both TTX-sensitive neuronal sodium channels (NaV1.1, NaV1.2, NaV1.3, NaV1.4 and NaV1.6) and the TTX-resistant cardiac sodium channel (NaV1.5) have been detected in cardiac myocytes, but relative levels of protein expression of the isoforms were not determined. Using a quantitative approach, we analyzed z-series of confocal microscopy images from individual mouse myocytes stained with either anti-NaV1.1, anti-NaV1.2, anti-NaV1.3, anti-NaV1.4, anti-NaV1.5, or anti-NaV1.6 antibodies and calculated the relative intensity of staining for these sodium channel isoforms. Our results indicate that the TTX-sensitive channels represented approximately 23% of the total channels, whereas the TTX-resistant NaV1.5 channel represented 77% of the total channel staining in mouse ventricular myocytes. These ratios are consistent with previous electrophysiological studies in mouse ventricular myocytes. NaV1.5 was located at the cell surface, with high density at the intercalated disc, but was absent from the transverse (t)-tubular system, suggesting that these channels support surface conduction and inter-myocyte transmission. Low-level cell surface staining of NaV1.4 and NaV1.6 channels suggest a minor role in surface excitation and conduction. Conversely, NaV1.1 and NaV1.3 channels are localized to the t-tubules and are likely to support t-tubular transmission of the action potential to the myocyte interior. This quantitative immunocytochemical approach for assessing sodium channel density and localization provides a more precise view of the relative importance and possible roles of these individual sodium channel protein isoforms in mouse ventricular myocytes and may be applicable to other species and cardiac tissue types., (© 2013.)

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is a powerful tool for the visualization of proteins in tissues and has demonstrated considerable diagnostic and prognostic value. One main challenge is that the molecular identity of such potential biomarkers mostly remains unknown. We introduce a generic method that removes this issue by systematically identifying the proteins embedded in the MALDI matrix using a combination of bottom-up and top-down proteomics. The analyses of ten human tissues lead to the identification of 1400 abundant and soluble proteins constituting the set of proteins detectable by MALDI IMS including >90% of all IMS biomarkers reported in the literature. Top-down analysis of the matrix proteome identified 124 mostly N- and C-terminally fragmented proteins indicating considerable protein processing activity in tissues. All protein identification data from this study as well as the IMS literature has been deposited into MaTisse, a new publically available database, which we anticipate will become a valuable resource for the IMS community.

We report that low percentages of dimethylsulfoxide (DMSO) in liquid chromatography solvents lead to a strong enhancement of electrospray ionization of peptides, improving the sensitivity of protein identification in bottom-up proteomics by up to tenfold. The method can be easily implemented on any LC-MS/MS system without modification to hardware or software and at no additional cost.

Chemotherapeutic drugs kill cancer cells, but it is unclear why this happens in responding patients but not in non-responders. Proteomic profiles of patients with oesophageal adenocarcinoma may be helpful in predicting response and selecting more effective treatment strategies. In this study, pretherapeutic oesophageal adenocarcinoma biopsies were analysed for proteomic changes associated with response to chemotherapy by MALDI imaging mass spectrometry. Resulting candidate proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and investigated for functional relevance in vitro. Clinical impact was validated in pretherapeutic biopsies from an independent patient cohort. Studies on the incidence of these defects in other solid tumours were included. We discovered that clinical response to cisplatin correlated with pre-existing defects in the mitochondrial respiratory chain complexes of cancer cells, caused by loss of specific cytochrome c oxidase (COX) subunits. Knockdown of a COX protein altered chemosensitivity in vitro, increasing the propensity of cancer cells to undergo cell death following cisplatin treatment. In an independent validation, patients with reduced COX protein expression prior to treatment exhibited favourable clinical outcomes to chemotherapy, whereas tumours with unchanged COX expression were chemoresistant. In conclusion, previously undiscovered pre-existing defects in mitochondrial respiratory complexes cause cancer cells to become chemosensitive: mitochondrial defects lower the cells' threshold for undergoing cell death in response to cisplatin. By contrast, cancer cells with intact mitochondrial respiratory complexes are chemoresistant and have a high threshold for cisplatin-induced cell death. This connection between mitochondrial respiration and chemosensitivity is relevant to anticancer therapeutics that target the mitochondrial electron transport chain., (Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Objectives: This study sought to evaluate the effect of systematic data analysis and standardized feedback on treatment times and outcome in a prospective multicenter trial., Background: Formalized data feedback may reduce treatment times in ST-segment elevation myocardial infarction (STEMI)., Methods: Over a 15-month period, 1,183 patients presenting with STEMI were enrolled. Six primary percutaneous coronary intervention hospitals in Germany and 29 associated nonpercutaneous coronary intervention hospitals participated. Data from patient contact to balloon inflation were collected and analyzed. Pre-defined quality indicators, including the percentage of patients with pre-announced STEMI, direct handoff in the catheterization laboratory, contact-to-balloon time <90 min, door-to-balloon time <60 min, and door-to-balloon time <30 min were discussed with staff on a quarterly basis., Results: Median door-to-balloon time decreased from 71 to 58 min and contact-to-balloon time from 129 to 103 min between the first and the fifth quarter (p < 0.05 for both). Contributing were shorter stays in the emergency department, more direct handoffs from ambulances to the catheterization laboratory (from 22% to 38%, p < 0.05), and a slight increase in the number of patients transported directly to the percutaneous coronary intervention facility (primary transport). One-year mortality was reduced in the total group of patients and in the subgroup of patients with primary transport (p < 0.05). The sharpest fall in mortality was observed in patients with primary transport and TIMI (Thrombolysis In Myocardial Infarction) risk score ≥ 3 (n = 521) with a decrease in 30-day mortality from 23.1% to 13.3% (p < 0.05) and in 1-year mortality from 25.6% to 16.7% (p < 0.05)., Conclusions: Formalized data feedback is associated with a reduction in treatment times for STEMI and with an improved prognosis, which is most pronounced in high-risk patients. (Feedback Intervention and Treatment Times in ST-Elevation Myocardial Infarction [FITT-STEMI]; NCT00794001)., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: In current guidelines, intraaortic balloon pumping (IABP) is considered a class 1 indication in cardiogenic shock complicating acute myocardial infarction. However, evidence is mainly based on retrospective or prospective registries with a lack of randomized clinical trials. Therefore, IABP is currently only used in 20% to 40% of cardiogenic shock cases. The hypothesis of this trial is that IABP in addition to early revascularization by either percutaneous coronary intervention or coronary artery bypass grafting will improve clinical outcome of patients in cardiogenic shock., Study Design: The IABP-SHOCK II study is a 600-patient, prospective, multicenter, randomized, open-label, controlled trial. The study is designed to compare the efficacy and safety of IABP versus optimal medical therapy on the background of early revascularization by either percutaneous coronary intervention or coronary artery bypass grafting. Patients will be randomized in a 1:1 fashion to 1 of the 2 treatments. The primary efficacy end point of IABP-SHOCK II is 30-day all-cause mortality. Secondary outcome measures, such as hemodynamic, laboratory, and clinical parameters, will serve as surrogate end points for prognosis. Furthermore, an intermediate and long-term follow-up at 6 and 12 months will be performed. Safety will be assessed, by the GUSTO bleeding definition, peripheral ischemic complications, sepsis, and stroke., Conclusions: The IABP-SHOCK II trial addresses important questions regarding the efficacy and safety of IABP in addition to early revascularization in patients with cardiogenic shock complicating myocardial infarction., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention.

Photoinduced charge separation in blends of organic materials of different electronic affinity and in organic donor-acceptor hybrids is a process of increasing importance for biological and artificial energy conversion and photovoltaics. Organic polymer solar cells are composed of an electron donor and an electron acceptor between which an electron transfer occurs after excitation by sunlight. Charge separation results in the formation of donor cation radicals and acceptor anion radicals. Here, we present our studies on a donor-acceptor hybrid molecule composed of a phenylene-bithiophene macrocycle used as a donor and a perylene bisimide acceptor. Using continuous wave EPR and modern pulsed EPR methodology in combination with light excitation, intermolecular as well as intramolecular charge separation has been observed. Light-induced charge separation observed upon selective excitation of either one of the chromophores indicates that both LUMO-based and HOMO-based electron transfer from donor to acceptor takes place. These experimental findings are corroborated by DFT calculations in which the HOMO of the donor-acceptor hybrid molecule is found at the phenylene-bithiophene macrocycle and the LUMO at the perylene bisimide., (© 2011 American Chemical Society)

A route towards phenylene-bithiophene macrocycles via oxidative thiophene coupling under pseudo-high dilution conditions is reported. This method is applied to the synthesis of a shape-persistent thiophene macrocycle with extraannularly attached perylenebisimide moieties that forms supramolecular aggregates at the solid/liquid interface.

The pharmacological induction of apoptosis in neoplastic B cells presents a promising therapeutic avenue for the treatment of chronic lymphocytic leukemia (CLL). We profiled a panel of clinical multi-kinase inhibitors for their ability to induce apoptosis in primary CLL cells. Whereas inhibitors targeting a large number of receptor and intracellular tyrosine kinases including c-KIT, FLT3, BTK and SYK were comparatively inactive, the CDK inhibitors BMS-387032 and flavopiridol showed marked efficacy similar to staurosporine. Using the kinobeads proteomics method, kinase expression profiles and binding profiles of the inhibitors to target protein complexes were quantitatively monitored in CLL cells. The targets most potently affected were CDK9, cyclin T1, AFF3/4 and MLLT1, which may represent four subunits of a deregulated positive transcriptional elongation factor (p-TEFb) complex. Albeit with lower potency, both drugs also bound the basal transcription factor BTF2/TFIIH containing CDK7. Staurosporine and geldanamycin do not affect these targets and thus seem to exhibit a different mechanism of action. The data support a critical role of p-TEFb inhibitors in CLL that supports their future clinical development.

Background/aims: The aim of the study was to characterize the whole cell current of the two-pore domain potassium channel TASK-1 (K2P3) in mouse ventricular cardiomyocytes (I(TASK-1)) and to analyze the cardiac phenotype of the TASK-1(-/-) mice., Methods and Results: We have quantified the ventricular I(TASK-1) current using the blocker A293 and TASK-1(-/-) mice. Surface electrocardiogram recordings of TASK-1(-/-) mice showed a prolonged QTc interval and a broadened QRS complex. The differences in electrocardiograms between wild type and TASK-1(-/-) mice disappeared during sympathetic stimulation of the animals. Quantitative RT-PCR, patch clamp recordings and measurements of hemodynamic performance of TASK-1(-/-) mice revealed no major compensatory changes in ion channel transcription. Action potential recordings of TASK-1(-/-) mouse cardiomyocytes indicated that I(TASK-1) modulates action potential duration. Our in vivo electrophysiological studies showed that isoflurane, which activates TASK-1, slowed heart rate and atrioventricular conduction of wild-type but not of TASK-1(-/-) mice., Conclusion: The results of an invasive electrophysiological catheter protocol in combination with the observed QRS time prolongation in the surface electrocardiogram point towards a regulatory role of TASK-1 in the cardiac conduction system., (Copyright © 2011 S. Karger AG, Basel.)

Calcium Channel Blockers (CCBs), competitive α-adrenoceptor blockers, and phenoxybenzamine (POB) are used for preoperative treatment of pheochromocytomas. We analyzed the protection from hypertensive crisis provided by these drugs during acute and chronic norepinephrine excess. To ensure adaptive changes during chronic norepinephrine (NE) excess, we continuously exposed male Wistar rats to NE for 3 weeks (osmotic pumps). Afterwards, blood pressure (BP) was continuously measured while NE boli (0-1000 μg/kg, i. v.) were administered before and after antihypertensive treatment in anesthetized and catheterized rats. A single dose of urapidil (10 mg/kg), nitrendipine (600 μg/kg) and POB (10 mg/kg) lowered BP from 212 ± 12 mmHg by 52 ± 7%, 31 ± 9%, and 50 ± 6%, respectively. With NE boli a maximum BP of 235 ± 29, 240 ± 30 and 138 ± 3 mmHg was measured in urapidil, nitrendipine, and POB treated animals (p<0.05). The number of hypertensive episodes (delta BP >30 mmHg) was 3 (3), 1.5 (0-3), and 0 (0-1) (p<0.05). Because of inferiority, urapidil was excluded from further testing. Chronically NE exposed rats were treated with POB (10 mg/kg/d), nifedipine (10 mg/kg/d), or vehicle for 7 days. Marked BP elevations were observed at baseline (167 ± 7, 210 ± 7 , and 217 ± 7 mmHg, p<0.01) and maximum blood pressure was 220 ± 32, 282 ± 26, and 268 ± 40 mmHg (p<0.001) with NE boli. Further stabilization was achieved combining POB pretreatment with a continuous nifedipine infusion, which effectively prevented BP elevations during NE excess. POB was the most effective drug used in monotherapy, but BP stabilization was superior using a combination of POB pretreatment with a continuous nifedipine infusion in this model., (© Georg Thieme Verlag KG Stuttgart · New York.)

The high incidence of sudden cardiac death in heart failure (HF) reflects electrophysiologic changes in response to myocardial failure. We previously showed that short-term variability of QT intervals (STV(QT)) identifies latent repolarization disorders in patients with drug-induced or congenital long QT syndrome. This study sought to determine (1) if STV(QT) is increased in patients with dilated cardiomyopathy (DC) and moderate congestive HF and (2) if increased STV(QT) is associated with ventricular arrhythmia in patients with HF. Sixty patients (53 +/- 12 years of age, 14 women) with DC and moderate HF (New York Heart Association classes II to III) were compared to matched controls. Twenty patients had implantable cardiac defibrillators secondary to a history of ventricular tachycardia (VT). Two cardiologists blinded to diagnosis manually measured QT intervals. Beat-to-beat variability of repolarization was determined from Poincaré plots of 30 consecutive QT intervals as was STV(QT). QTc intervals were comparable in patients and controls (419 +/- 36 vs 415 +/- 32 ms, respectively, p >0.05), whereas STV(QT) was significantly higher in patients with HF (7.8 +/- 3 vs 4.1 +/- 2 ms, respectively, p <0.05). STV(QT) was more increased in patients with a history of VT compared to those without VT (10.1 +/- 2 vs 6.6 +/- 2 ms, respectively, p <0.05). Increased STV(QT) and decreased ejection fraction were associated with a history of VT; however, STV(QT) was the strongest indicator. In conclusion, the present study demonstrates for the first time that STV(QT) is increased in patients with DC with HF. Patients with DC and HF and implantable cardiac defibrillators for secondary prevention had the highest STV(QT). Thus, increased STV(QT) in the context of moderate HF may reflect a latent repolarization disorder and increased susceptibility to sudden death in patients with DC, which is not identified by a prolonged QT interval., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Background: The differential diagnosis of hyponatremia is often challenging because of its association with multiple underlying pathophysiological mechanisms, diseases, and treatment options. Several algorithms are available to guide the diagnostic approach to hyponatremia, but their diagnostic and clinical utility has never been evaluated. We aimed to assess in detail the diagnostic utility as well as the limitations of the existing approaches to hyponatremia., Methods: Each of the 121 consecutive subjects presenting with hyponatremia (serum sodium <130 mmoL/L) underwent 3 different and independent diagnostic and therapeutic approaches: inexperienced doctor applying an established Algorithm, intensive care senior physicians acting as Senior Physician, and senior endocrinologist serving as Reference Standard., Results: The overall diagnostic agreement between Algorithm and Reference Standard was 71% (respective Cohen's kappa and delta values were 0.64 and 0.70), the overall diagnostic agreement between Senior Physician and Reference Standard was 32% (0.20 and 0.19, respectively). Regarding the therapeutic consequences, the diagnostic accuracy of the Algorithm was 86% (0.70 and 0.72, respectively) and of the Senior Physician was 48% (0.01 and 0.04, respectively). In retrospect, by disregarding the patient's extracellular fluid volume and assessing the effective arterial blood volume by determination of the fractional urate excretion, the Algorithm improved its diagnostic accuracy to 95%., Conclusion: Although the Algorithm performed reasonably well, several shortcomings became apparent, rendering it difficult to apply the Algorithm without reservation. Whether some modifications may enhance its diagnostic accuracy and simplify the management of hyponatremia needs to be determined., (Copyright 2010 Elsevier Inc. All rights reserved.)

Aims: Clinical observations in patients with long QT syndrome carrying sodium channel mutations (LQT3) suggest that bradycardia caused by parasympathetic stimulation may provoke torsades de pointes (TdP). Beta-adrenoceptor blockers appear less effective in LQT3 than in other forms of the disease., Methods and Results: We studied effects of autonomic modulation on arrhythmias in vivo and in vitro and quantified sympathetic innervation by autoradiography in heterozygous mice with a knock-in deletion (DeltaKPQ) in the Scn5a gene coding for the cardiac sodium channel and increased late sodium current (LQT3 mice). Cholinergic stimulation by carbachol provoked bigemini and TdP in freely roaming LQT3 mice. No arrhythmias were provoked by physical stress, mental stress, isoproterenol, or atropine. In isolated, beating hearts, carbachol did not prolong action potentials per se, but caused bradycardia and rate-dependent action potential prolongation. The muscarinic inhibitor AFDX116 prevented effects of carbachol on heart rate and arrhythmias. beta-Adrenoceptor stimulation suppressed arrhythmias, shortened rate-corrected action potential duration, increased rate, and minimized difference in late sodium current between genotypes. Beta-adrenoceptor density was reduced in LQT3 hearts. Acute beta-adrenoceptor blockade by esmolol, propranolol or chronic propranolol in vivo did not suppress arrhythmias. Chronic flecainide pre-treatment prevented arrhythmias (all P < 0.05)., Conclusion: Cholinergic stimulation provokes arrhythmias in this model of LQT3 by triggering bradycardia. beta-Adrenoceptor density is reduced, and beta-adrenoceptor blockade does not prevent arrhythmias. Sodium channel blockade and beta-adrenoceptor stimulation suppress arrhythmias by shortening repolarization and minimizing difference in late sodium current.

Aims: Heart failure patients are often equipped with implanted devices and are frequently hospitalized due to volume overload. Reliable prediction of imminent fluid congestion has the potential to provide early detection of cardiac decompensation and therefore might be capable of enhancing therapy management. We investigated whether implant-based impedance (Z) measurement is closely correlated with directly assessed extravascular lung water and might thus be useful for patient monitoring., Methods and Results: In sheep, pulmonary fluid congestion was induced. Continuous haemodynamic monitoring was performed and extravascular lung water index (EVLWI) assessed. An implanted device with a right ventricular lead measured Z using different electrode configurations. All animals developed gradual pulmonary fluid accumulation leading to inclining lung oedema: EVLWI did increase from 9.5 +/- 1 to 21.1 +/- 5.1 mL/kg (+127%). A concomitant decrease of Z by up to 23%, depending on the electrode configuration, was observed and regression analysis between Z and EVLWI yielded a significant inverse correlation., Conclusion: Changes of Z show a strong inverse correlation with changes of directly measured EVLWI. This allows the application of Z as a measure of intrathoracic fluid status and has the potential to optimize patient care, especially in the context of evolving telemedicine concepts.

Voltage-gated sodium channels are composed of pore-forming alpha- and auxiliary beta-subunits and are responsible for the rapid depolarization of cardiac action potentials. Recent evidence indicates that neuronal tetrodotoxin (TTX) sensitive sodium channel alpha-subunits are expressed in the heart in addition to the predominant cardiac TTX-resistant Na(v)1.5 sodium channel alpha-subunit. These TTX-sensitive isoforms are preferentially localized in the transverse tubules of rodents. Since neonatal cardiomyocytes have yet to develop transverse tubules, we determined the complement of sodium channel subunits expressed in these cells. Neonatal rat ventricular cardiomyocytes were stained with antibodies specific for individual isoforms of sodium channel alpha- and beta-subunits. alpha-actinin, a component of the z-line, was used as an intracellular marker of sarcomere boundaries. TTX-sensitive sodium channel alpha-subunit isoforms Na(v)1.1, Na(v)1.2, Na(v)1.3, Na(v)1.4 and Na(v)1.6 were detected in neonatal rat heart but at levels reduced compared to the predominant cardiac alpha-subunit isoform, Na(v)1.5. Each of the beta-subunit isoforms (beta1-beta4) was also expressed in neonatal cardiac cells. In contrast to adult cardiomyocytes, the alpha-subunits are distributed in punctate clusters across the membrane surface of neonatal cardiomyocytes; no isoform-specific subcellular localization is observed. Voltage clamp recordings in the absence and presence of 20 nM TTX provided functional evidence for the presence of TTX-sensitive sodium current in neonatal ventricular myocardium which represents between 20 and 30% of the current, depending on membrane potential and experimental conditions. Thus, as in the adult heart, a range of sodium channel alpha-subunits are expressed in neonatal myocytes in addition to the predominant TTX-resistant Na(v)1.5 alpha-subunit and they contribute to the total sodium current., (Copyright 2009 Elsevier Inc. All rights reserved.)

Background: Transgenic (TG) Ca/calmodulin-dependent protein kinase II (CaMKII)delta(C) mice have heart failure and isoproterenol (ISO)-inducible arrhythmias. We hypothesized that CaMKII contributes to arrhythmias and underlying cellular events and that inhibition of CaMKII reduces cardiac arrhythmogenesis in vitro and in vivo., Methods and Results: Under baseline conditions, isolated cardiac myocytes from TG mice showed an increased incidence of early afterdepolarizations compared with wild-type myocytes (P<0.05). CaMKII inhibition (AIP) completely abolished these afterdepolarizations in TG cells (P<0.05). Increasing intracellular Ca stores using ISO (10(-8) M) induced a larger amount of delayed afterdepolarizations and spontaneous action potentials in TG compared with wild-type cells (P<0.05). This seems to be due to an increased sarcoplasmic reticulum (SR) Ca leak because diastolic [Ca](i) rose clearly on ISO in TG but not in wild-type cells (+20+/-5% versus +3+/-4% at 10(-6) M ISO, P<0.05). In parallel, SR Ca leak assessed by spontaneous SR Ca release events showed an increased Ca spark frequency (3.9+/-0.5 versus 2.0+/-0.4 sparks per 100 microm(-1).s(-1), P<0.05). However, CaMKII inhibition (either pharmacologically using KN-93 or genetically using an isoform-specific CaMKIIdelta-knockout mouse model) significantly reduced SR Ca spark frequency, although this rather increased SR Ca content. In parallel, ISO increased the incidence of early (54% versus 4%, P<0.05) and late (86% versus 43%, P<0.05) nonstimulated events in TG versus wild-type myocytes, but CaMKII inhibition (KN-93 and KO) reduced these proarrhythmogenic events (P<0.05). In addition, CaMKII inhibition in TG mice (KN-93) clearly reduced ISO-induced arrhythmias in vivo (P<0.05)., Conclusions: We conclude that CaMKII contributes to cardiac arrhythmogenesis in TG CaMKIIdelta(C) mice having heart failure and suggest the increased SR Ca leak as an important mechanism. Moreover, CaMKII inhibition reduces cardiac arrhythmias in vitro and in vivo and may therefore indicate a potential role for future antiarrhythmic therapies warranting further studies.

Background: Transforming growth factor (TGF)-beta is a locally generated cytokine involved in healing processes and tissue fibrosis, all relevant for cardiac remodeling and the development of heart failure after myocardial infarction (MI). However, data regarding the function of TGF-beta after ischemic injury are inconclusive., Methods and Results: We tested the effect of TGF-beta inhibition by application of a blocking antibody in mice with MI. Starting 1 week before or 5 days after coronary artery ligation mice were treated with intraperitoneal injections of an anti-TGF-beta (5 mg/kg bodyweight 1D11, Genzyme) or control antibody. Mortality over 8 weeks was significantly higher in the groups treated with the anti-TGF-beta antibody. Both, pre or post MI treatments were associated with increased left ventricular dilatation after MI as determined by serial echocardiography. In anti-TGF-beta treated mice collagen production decreased and matrix-metalloproteinase expression increased. However, the expression of TGF pro-inflammatory cytokine TNF-alpha was not altered by the treatment. Anti-TGF-beta treatment before or after coronary artery ligation increases mortality and worsens left ventricular remodeling in mice with non-reperfused MI. The detrimental effects of TGF-beta inhibition may be mediated by alterations in extracellular matrix remodeling.

Background: Several studies showed the beneficial effect of pacemaker implantation on cognitive performance in patients with bradycardia. But it has never been investigated if patients with chronotropic incompetence may improve their cognitive performance if treated by a rate-adaptive system reacting to mental stress in comparison to the most frequently used accelerometer-driven pacing., Methods: The randomized, single-blind, multicenter COGNITION study evaluates if closed loop stimulation (CLS) offers incremental benefit in the speed of cognitive performance and the overall well-being of elderly patients with bradycardia compared with accelerometer-based pacing. Four hundred chronotropically incompetent patients older than 55 years will be randomized 3-6 weeks after implantation to CLS or accelerometer sensor. Follow-up visits are performed after 12 and 24 months. The speed of cognitive performance, which is the underlying function influencing all other aspects of cognitive performance, will be assessed by the number connection test, a standardized psychometric test for the elderly. Secondary endpoints include patient self-assessment of different aspects of health (by visual analogue scales), quality of life (by SF-8 health survey), the incidence of atrial fibrillation (episodes lasting for longer than 24 hours), and the frequency of serious adverse events., Conclusion: In the ongoing COGNITION study, we aim at long-term comparison of two rate-adaptive systems, focusing on the cognitive performance of the patients, which was neglected in the past evaluation of pacemaker sensors.

Aims: We compared pacing rate adaptation based on closed loop stimulation (CLS) or accelerometer sensor (AS) during acute mental and physical stress in the same patient., Methods and Results: One month after Protos (Biotronik, Germany) pacemaker implantation, 131 chronotropically incompetent patients were randomized to AS or CLS for 3 months with crossover. Arithmetic and 6 min walk tests were performed in the non-rate-adaptive mode and AS and CLS rate-adaptive modes, respectively. At the end, patients had to select the individually preferred pacemaker sensor. Heart rate during mental stress was higher (3.0 +/- 9.2 bpm) in the CLS than in the AS mode (P = 0.004). Benefit in the walking distance compared with non-rate-adaptive pacing was similar for the two modes: added 27 +/- 96 m (AS, P = 0.013) and 30 +/- 116 m (CLS, P = 0.025). At the end of the walk, heart rate was higher by 4.8 +/- 21.4 bpm in AS than in CLS (P = 0.049). Twice as many patients preferred CLS over AS (P < 0.01)., Conclusion: The arithmetic test was associated with a significantly higher heart rate for CLS than for AS, showing a greater sensitivity of CLS-based rate adaptation to mental stress. Performance during physical stress was comparable. Patients preferred CLS.

In neurons, voltage-gated sodium channel beta subunits regulate the expression levels, subcellular localization, and electrophysiological properties of sodium channel alpha subunits. However, the contribution of beta subunits to sodium channel function in heart is poorly understood. We examined the role of beta1 in cardiac excitability using Scn1b null mice. Compared to wildtype mice, electrocardiograms recorded from Scn1b null mice displayed longer RR intervals and extended QT(c) intervals, both before and after autonomic block. In acutely dissociated ventricular myocytes, loss of beta1 expression resulted in a approximately 1.6-fold increase in both peak and persistent sodium current while channel gating and kinetics were unaffected. Na(v)1.5 expression increased in null myocytes approximately 1.3-fold. Action potential recordings in acutely dissociated ventricular myocytes showed slowed repolarization, supporting the extended QT(c) interval. Immunostaining of individual myocytes or ventricular sections revealed no discernable alterations in the localization of sodium channel alpha or beta subunits, ankyrin(B), ankyrin(G), N-cadherin, or connexin-43. Together, these results suggest that beta1 is critical for normal cardiac excitability and loss of beta1 may be associated with a long QT phenotype.

The role of the neuronal NO synthase (nNOS or NOS1) enzyme in the control of cardiac function still remains unclear. Results from nNOS(-/-) mice or from pharmacological inhibition of nNOS are contradictory and do not pay tribute to the fact that probably spatial confinement of the nNOS enzyme is of major importance. We hypothesize that the close proximity of nNOS and certain effector molecules like L-type Ca(2+)-channels has an impact on myocardial contractility. To test this, we generated a new transgenic mouse model allowing conditional, myocardial specific nNOS overexpression. Western blot analysis of transgenic nNOS overexpression showed a 6-fold increase in nNOS protein expression compared with noninduced littermates (n=12; P<0.01). Measuring of total NOS activity by conversion of [(3)H]-l-arginine to [(3)H]-l-citrulline showed a 30% increase in nNOS overexpressing mice (n=18; P<0.05). After a 2 week induction, nNOS overexpression mice showed reduced myocardial contractility. In vivo examinations of the nNOS overexpressing mice revealed a 17+/-3% decrease of +dp/dt(max) compared with noninduced mice (P<0.05). Likewise, ejection fraction was reduced significantly (42% versus 65%; n=15; P<0.05). Interestingly, coimmunoprecipitation experiments indicated interaction of nNOS with SR Ca(2+)ATPase and additionally with L-type Ca(2+)- channels in nNOS overexpressing animals. Accordingly, in adult isolated cardiac myocytes, I(Ca,L) density was significantly decreased in the nNOS overexpressing cells. Intracellular Ca(2+)-transients and fractional shortening in cardiomyocytes were also clearly impaired in nNOS overexpressing mice versus noninduced littermates. In conclusion, conditional myocardial specific overexpression of nNOS in a transgenic animal model reduced myocardial contractility. We suggest that nNOS might suppress the function of L-type Ca(2+)-channels and in turn reduces Ca(2+)-transients which accounts for the negative inotropic effect.

In heart failure (HF), Ca(2+)/calmodulin kinase II (CaMKII) expression is increased. Altered Na(+) channel gating is linked to and may promote ventricular tachyarrhythmias (VTs) in HF. Calmodulin regulates Na(+) channel gating, in part perhaps via CaMKII. We investigated effects of adenovirus-mediated (acute) and Tg (chronic) overexpression of cytosolic CaMKIIdelta(C) on Na(+) current (I(Na)) in rabbit and mouse ventricular myocytes, respectively (in whole-cell patch clamp). Both acute and chronic CaMKIIdelta(C) overexpression shifted voltage dependence of Na(+) channel availability by -6 mV (P < 0.05), and the shift was Ca(2+) dependent. CaMKII also enhanced intermediate inactivation and slowed recovery from inactivation (prevented by CaMKII inhibitors autocamtide 2-related inhibitory peptide [AIP] or KN93). CaMKIIdelta(C) markedly increased persistent (late) inward I(Na) and intracellular Na(+) concentration (as measured by the Na(+) indicator sodium-binding benzofuran isophthalate [SBFI]), which was prevented by CaMKII inhibition in the case of acute CaMKIIdelta(C) overexpression. CaMKII coimmunoprecipitates with and phosphorylates Na(+) channels. In vivo, transgenic CaMKIIdelta(C) overexpression prolonged QRS duration and repolarization (QT intervals), decreased effective refractory periods, and increased the propensity to develop VT. We conclude that CaMKII associates with and phosphorylates cardiac Na(+) channels. This alters I(Na) gating to reduce availability at high heart rate, while enhancing late I(Na) (which could prolong action potential duration). In mice, enhanced CaMKIIdelta(C) activity predisposed to VT. Thus, CaMKII-dependent regulation of Na(+) channel function may contribute to arrhythmogenesis in HF.

Clinical trials failed to show a beneficial effect of postmenopausal hormone replacement therapy, whereas experimental studies in young animals reported a protective function of estrogen replacement in cardiovascular disease. Because these diverging results could in part be explained by aging effects, we compared the efficacy of estrogen substitution to modulate cardiac hypertrophy and cardiac gene expression among young (age 3 months) and senescent (age 24 months) spontaneously hypertensive rats (SHRs), which were sham operated or ovariectomized and injected with placebo or identical doses of 17beta-estradiol (E2; 2 microg/kg body weight per day) for 6 weeks (n=10/group). Blood pressure was comparable among sham-operated senescent and young SHRs and not altered by ovariectomy or E2 treatment among young or among senescent rats. Estrogen substitution inhibited uterus atrophy and gain of body weight in young and senescent ovariectomized SHRs, but cardiac hypertrophy was attenuated only in young rats. Cardiac estrogen receptor-alpha expression was lower in intact and in ovariectomized senescent compared with young SHRs and increased with estradiol substitution in aged rats. Plasma estradiol and estrone levels were lower not only in sham-operated but surprisingly also in E2-substituted senescent SHRs and associated with a reduction of hepatic 17beta-hydroxysteroid dehydrogenase type 1 enzyme activity, which converts weak (ie, estrone) into potent estrogens, such as E2. Aging attenuates the antihypertrophic effect of estradiol in female SHRs and is associated with profound alterations in cardiac estrogen receptor-alpha expression and estradiol metabolism. These observations contribute to explain the lower efficiency of estrogen substitution in senescent SHRs.

Objective: To evaluate lenalidomide in the treatment of multiple myeloma and myelodysplastic syndrome (MDS)., Data Sources: Clinical literature was accessed through MEDLINE (1966-August 2005), Science Citation Index (1980-August 2005), and Proceedings of the American Society of Hematology (2000-2004)., Data Synthesis: New analogs of thalidomide have been synthesized that are more potent and less toxic. Lenalidomide (CC-5013) is currently in Phase III trials for the treatment of multiple myeloma and MDS. Phase II trials demonstrated lenalidomide's efficacy in patients refractory to thalidomide. The full potential of this agent has yet to be proven, but preliminary data seem promising., Conclusions: Lenalidomide is a potent immunomodulating drug that offers different mechanisms of action and therapeutic potential for the treatment of multiple myeloma, MDS, and other malignancies.

The authors have created transgenic mouse models of hypertrophic cardiomyopathy with mutations in either cardiac troponin T or myosin heavy chain. Mice mutant in myosin heavy chain develop significant cardiac hypertrophy at young adult age. Female mice keep that hypertrophic state, whereas male mice undergo progressive dilatation and exhibit systolic dysfunction at older age. Mice mutant in troponin, however, exhibit no baseline hypertrophy. When put under chronic adrenergic stress, all male mice die suddenly, whereas female mice show no mortality. These examples highlight the aggravated phenotype in male mice modeling hypertrophic cardiomyopathy and are a starting point to new mechanistic experiments.

Cardiomyocytes are notoriously difficult to transfect using standard techniques unless viral vectors such as recombinant adenoviruses are used. Generation of recombinant adenoviruses is, however, a complex and time-consuming procedure and not possible for every DNA construct. We therefore optimized DNA/polylysine/adenovirus complexing for efficient gene transfer in neonatal rat cardiomyocytes determining the critical parameters for this method. Importantly, not only the concentration of the various components but also the method used for plasmid purification is critical for this transfection technique. Cesium-chloride-purified DNA is inferior to anion-exchange methods for this purpose possibly because of altered ionic properties. In the second part of this study, we could demonstrate silent gene transfer into cardiomyocytes applying this optimized technique to plasmids encoding luciferase or beta-galactosidase cDNAs under the control of the cytomegalovirus immediate-early promoter. Phorbol myristate acetate and/or forskolin increased the amount of beta-galactosidase positive cells up to fivefold. Luciferase activity could even be increased as much as ninefold. These results demonstrate that the cytomegalovirus promoter is not maximally active in neonatal rat cardiomyocytes under basal conditions. In fact, a large proportion of cells is silently transfected and seems to express (an) inhibitor(s) of transcription from the CMV promoter that can be overcome by stimulation of cAMP- or protein kinase C-dependent pathways.

Background: Transgenic mouse models expressing a missense mutation (R92Q) or a splice donor site mutation (trunc) in the cardiac troponin T (cTnT) model familial hypertrophic cardiomyopathy (FHC) in humans. Although males from these strains share the unusual property of having significantly smaller ventricles and cardiac myocytes, they differ with regard to systolic function, fibrosis, and gene expression. Little is known about how these phenotypes affect the responses to additional pathological stimuli., Methods and Results: We tested the ability of hearts of both sexes of wild-type and mutant mice to respond to defined pathological, pharmacological, hypertrophic stimuli in vivo. Hearts of mutant cTnT models of both sexes were able to undergo hypertrophy in response to at least one stimulus, but the extent differed between the 2 mutants and was sex specific. Interestingly, the trunc-mutant mouse heart was resistant to the development of fibrosis in response to pharmacological stimuli. Stimulation with 2 adrenergic agonists led to sudden cardiac death of all male but not female mutant animals, which suggests altered adrenergic responsiveness in these 2 models of FHC., Conclusions: Hypertrophic signaling is differentially affected by distinct mutations in cTnT and is sex modified. Hearts can respond with either an augmented hypertrophic and fibrotic response or a diminished hypertrophy and resistance to fibrosis. Sudden cardiac death is related to adrenergic stress and is independent of the development of fibrosis but occurred only in male mice. These results suggest that patients with certain TnT mutations may respond to certain pathological situations with a worsened phenotype.

The majority of Na+ channels in the heart are composed of the tetrodotoxin (TTX)-resistant (KD, 2-6 microm) Nav1.5 isoform; however, recently it has been shown that TTX-sensitive (KD, 1-10 nm) neuronal Na+ channel isoforms (Nav1.1, Nav1.3 and Nav1.6) are also present and functionally important in the myocytes of the ventricles and the sinoatrial (SA) node. In the present study, in mouse SA node pacemaker cells, we investigated Na+ currents under physiological conditions and the expression of cardiac and neuronal Na+ channel isoforms. We identified two distinct Na+ current components, TTX resistant and TTX sensitive. At 37 degrees C, TTX-resistant iNa and TTX-sensitive iNa started to activate at approximately -70 and approximately -60 mV, and peaked at -30 and -10 mV, with a current density of 22 +/- 3 and 18 +/- 1 pA pF(-1), respectively. TTX-sensitive iNa inactivated at more positive potentials as compared to TTX-resistant iNa. Using action potential clamp, TTX-sensitive iNa was observed to activate late during the pacemaker potential. Using immunocytochemistry and confocal microscopy, different distributions of the TTX-resistant cardiac isoform, Nav1.5, and the TTX-sensitive neuronal isoform, Nav1.1, were observed: Nav1.5 was absent from the centre of the SA node, but present in the periphery of the SA node, whereas Nav1.1 was present throughout the SA node. Nanomolar concentrations (10 or 100 nm) of TTX, which block TTX-sensitive iNa, slowed pacemaking in both intact SA node preparations and isolated SA node cells without a significant effect on SA node conduction. In contrast, micromolar concentrations (1-30 microm) of TTX, which block TTX-resistant iNa as well as TTX-sensitive iNa, slowed both pacemaking and SA node conduction. It is concluded that two Na+ channel isoforms are important for the functioning of the SA node: neuronal (putative Nav1.1) and cardiac Nav1.5 isoforms are involved in pacemaking, although the cardiac Nav1.5 isoform alone is involved in the propagation of the action potential from the SA node to the surrounding atrial muscle.

We report the case of a 64-year-old woman who was admitted to our hospital for radiofrequency ablation of isthmus-dependent counterclockwise atrial flutter. Following an initially uncomplicated right atrial linear isthmus ablation that was associated with conversion of atrial flutter to sinus rhythm and evidence of complete isthmus block, the patient developed a small pericardial effusion, a marked and recurrent left-sided pleural effusion, and had significantly elevated inflammatory markers. After an extensive diagnostic work-up which excluded infectious, malignant and thromboembolic causes of the effusions, a diagnosis of postcardiac injury syndrome was made and the patient was treated with oral corticosteroids and nonsteroidal anti-inflammatory drugs. Over a treatment period of 2 months there was complete resolution of the pericardial and left-sided pleural effusions and normalization of inflammatory markers. Postcardiac injury syndrome is a rare complication of radiofrequency ablation that is characterized by signs of pericardial, pleural and pulmonary parenchymal inflammation.

Background: Voltage-gated sodium channels composed of pore-forming alpha and auxiliary beta subunits are responsible for the rising phase of the action potential in cardiac muscle, but their localizations have not yet been clearly defined., Methods and Results: Immunocytochemical studies show that the principal cardiac alpha subunit isoform Na(v)1.5 and the beta2 subunit are preferentially localized in intercalated disks, identified by immunostaining of connexin 43, the major protein of cardiac gap junctions. The brain alpha subunit isoforms Na(v)1.1, Na(v)1.3, and Na(v)1.6 are preferentially localized with beta1 and beta3 subunits in the transverse tubules, identified by immunostaining of alpha-actinin, a cardiac z-line protein. The beta1 subunit is also present in a small fraction of intercalated disks. The recently cloned beta4 subunit, which closely resembles beta2 in amino acid sequence, is also expressed in ventricular myocytes and is localized in intercalated disks as are beta2 and Na(v)1.5., Conclusions: Our results suggest that the primary sodium channels present in ventricular myocytes are composed of Na(v)1.5 plus beta2 and/or beta4 subunits in intercalated disks and Na(v)1.1, Na(v)1.3, and Na(v)1.6 plus beta1 and/or beta3 subunits in the transverse tubules.

Voltage-gated Na(+) channels are composed of pore-forming alpha and auxiliary beta subunits. The majority of Na(+) channels in the heart contain tetrodotoxin (TTX)-insensitive Na(v)1.5 alpha subunits, but TTX-sensitive brain-type Na(+) channel alpha subunits are present and functionally important in the transverse tubules of ventricular myocytes. Sinoatrial (SA) nodal cells were identified in cardiac tissue sections by staining for connexin 43 (which is expressed in atrial tissue but not in SA node), and Na(+) channel localization was analyzed by immunocytochemical staining with subtype-specific antibodies and confocal microscopy. Brain-type TTX-sensitive Na(v)1.1 and Na(v)1.3 alpha subunits and all four beta subunits were present in mouse SA node, but Na(v)1.5 alpha subunits were not. Na(v)1.1 alpha subunits were also present in rat SA node. Isolated mouse hearts were retrogradely perfused in a Langendorff preparation, and electrocardiograms were recorded. Spontaneous heart rate and cycle length were constant, and heart rate variability was small under control conditions. In contrast, in the presence of 100 nM TTX to block TTX-sensitive Na(+) channels specifically, we observed a significant reduction in spontaneous heart rate and markedly greater heart rate variability, similar to sick-sinus syndrome in man. We hypothesize that brain-type Na(+) channels are required because their more positive voltage dependence of inactivation allows them to function at the depolarized membrane potential of SA nodal cells. Our results demonstrate an important contribution of TTX-sensitive brain-type Na(+) channels to SA nodal automaticity in mouse heart and suggest that they may also contribute to SA nodal function and dysfunction in human heart.

Propafenone is a class I antiarrhythmic drug used to suppress cardiac arrhythmia both of atrial and ventricular origin. We measured fast sodium current (I(Na)+) directly with the loose-patch-clamp technique and confirm the frequency-dependent block of this current. Effects on steady-state current kinetics were small or even in the opposite direction. Since propafenone interacts with the beta-adrenergic receptor and stimulation of this receptor itself increases I(Na)+, propafenone was combined with isoproterenol (100 nmol/L). Now we found an augmentation of the frequency-dependent block of I(Na)+. Together with the beta-receptor antagonist atenolol, propafenone exhibited more class I potency but the frequency-dependent block of propafenone was only slightly increased. We conclude that the augmentation of the frequency-dependent effect was predominantly due to phosphorylation of the sodium channel and not due to displacement of propafenone from the beta-receptor. Nevertheless, in clinical settings with various states of the sympathetic tone one has to be aware of different propafenone effects.

Voltage-gated sodium channels composed of pore-forming alpha and auxiliary beta subunits are responsible for the rising phase of the action potential in cardiac muscle, but the functional roles of distinct sodium channel subtypes have not been clearly defined. Immunocytochemical studies show that the principal cardiac pore-forming alpha subunit isoform Na(v)1.5 is preferentially localized in intercalated disks, whereas the brain alpha subunit isoforms Na(v)1.1, Na(v)1.3, and Na(v)1.6 are localized in the transverse tubules. Sodium currents due to the highly tetrodotoxin (TTX)-sensitive brain isoforms in the transverse tubules are small and are detectable only after activation with beta scorpion toxin. Nevertheless, they play an important role in coupling depolarization of the cell surface membrane to contraction, because low TTX concentrations reduce left ventricular function. Our results suggest that the principal cardiac isoform in the intercalated disks is primarily responsible for action potential conduction between cells and reveal an unexpected role for brain sodium channel isoforms in the transverse tubules in coupling electrical excitation to contraction in cardiac muscle.