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7,000 | [Acute phase of Chagas disease in the Brazilian Amazon region: study of 233 cases from Pará, Amapá and Maranhão observed between 1988 and 2005]. | Two hundred and thirty-three cases of the acute phase of Chagas disease, from Pará, Amapá and Maranhão, were observed between 1988 and 2005. One hundred and sixty were studied retrospectively from 1988 to 2002 and seventy-three were prospectively followed up from 2003 to 2005. Among the cases studied, 78.5% (183/233) formed part of outbreaks, probably due to oral transmission (affecting a mean of 4 individuals), and 21.5% (50/233) were isolated cases. Cases were taken to be acute if they presented positive direct parasitological tests (fresh blood, thick drop or Quantitative Buffy Coat, QBC) and/or positive anti Trypanosoma cruzi IgM. Xenodiagnosis was also performed on 224 patients and blood culturing on 213. All the patients had clinical and epidemiological evaluations. The most frequent clinical manifestations were fever (100%), headache (92.3%), myalgia (84.1%), pallor (67%), dyspnea (58.4%), swelling of the legs (57.9%), facial edema (57.5%), abdominal pain (44.3%), myocarditis (39.9%) and exanthema (27%). The electrocardiogram showed abnormalities of ventricular repolarization in 38.5%, low QRS voltage in 15.4%, left-axis deviation in 11.5%, ventricular ectopic beats in 5.8%, bradycardia in 5.8%, tachycardia in 5.8%, right branch block in 4.8% and atrial fibrillation in 4.8%. The most frequently observed abnormality on the echocardiogram was pericardial effusion, in 46.2% of the cases. Thirteen (5.6%) patients died: ten (76.9%) of them due to cardiovascular involvement, two due to digestive complications and one due to indeterminate causes. |
7,001 | Reversible dilated cardiomyopathy associated with post-partum thyrotoxic storm. | The following case of a young mother presenting with post-partum pulmonary oedema, highlights a singular and life-threatening complication of a common condition (thyrotoxicosis). While thyrotoxic heart disease is well described, thyrotoxic storm in the post-partum period associated with dilated cardiomyopathy, congestive cardiac failure and ventricular fibrillation is exceptional. |
7,002 | Isoelectric PVCs diagnosed with a monitor with simultaneous ECG, and ICD intracardiac electrogram and marker channels. | A 78-year-old woman with a remote history of chronic atrial fibrillation and catheter ablation of the atrioventricular node with a permanent ventricular pacemaker sustained a syncopal episode. Interrogation of her pacemaker revealed electrograms of ventricular fibrillation with a duration of 26 seconds. The patient underwent upgrade to an implantable cardioverter defibrillator (ICD). Postimplant, on telemetry, pauses were seen without pacing artifact, suspicious for oversensing of something by the ICD. Interrogation and threshold testing of the ICD established that both sensing (of her junctional escape rhythm) and pacing thresholds were excellent. A Holter monitor was utilized to evaluate the patient's rhythm and device function. It incorporated simultaneous tracings from multiple surface electrocardiogram leads and both intracardiac electrograms and marker channel recordings from the ICD. The causes for the pauses were found to be isoelectric premature ventricular complexes not seen on the telemetry tracings. |
7,003 | Drug therapy for atrial fibrillation: what will its role be in the era of increasing use of catheter ablation? | Atrial fibrillation (AF) is an increasingly important disorder. In most patients the treatment of AF usually employs anti-arrhythmic drugs (AADs). Despite the widespread utilization of AADs for the conversion of atrial fibrillation and maintenance of normal sinus rhythm, their use is limited by modest efficacy, frequent intolerance, and the potential for serious ventricular proarrhythmia and organ toxicity. In addition to AADs, ablations for AF have come into vogue. If ablation techniques improve, one might ask whether there will still be a role for AADs, and, if so, what will it be and what agents will be used. This manuscript will attempt to answer these questions. |
7,004 | Ventricular proarrhythmic effects of atrial fibrillation are modulated by depolarization and repolarization anomalies in patients with left ventricular dysfunction. | Atrial fibrillation (AF) may have a ventricular proarrhythmic effect, particularly in the setting of heart failure. We assessed whether AF predicts appropriate implantable cardioverter-defibrillator (ICD) shocks in patients with left ventricular dysfunction and explored modulators of risk.</AbstractText>A retrospective cohort study was conducted on 215 consecutive patients with ICDs for primary prevention having a left ventricular ejection fraction < or = 35%. Mean age at ICD implantation was 61.0 +/- 9.7 years and 17% were women. Overall, 22 patients (10.2%) experienced appropriate ICD shocks over a follow-up of 1.3 +/- 0.7 years, corresponding to an actuarial event-rate of 5.8% per year. In univariate analysis, AF was associated with a 3.6-fold increased risk of appropriate shocks (P = 0.0037). Annual rates of appropriate ICD shocks in patients with and without AF were 12.9% and 3.5%, respectively (P = 0.0200). In multivariate stepwise Cox regression analyses controlling for baseline imbalances, demographic parameters, underlying heart disease, and therapy, history of AF independently predicted appropriate shocks (hazard ratio 2.7, P = 0.0278). Prolonged QRS duration (>130 ms) and QTc (>440 ms) modulated the effect of AF on appropriate shocks. Patients with both AF and QRS > 130 ms were more than five times more likely to receive an appropriate ICD shock (hazard ratio 5.4, P = 0.0396). Patients with AF and QTc > 440 ms experienced a greater than 12-fold increased risk of appropriate shocks (hazard ratio 12.7, P = 0.0177).</AbstractText>In prophylactic ICD recipients with left ventricular dysfunction, AF is associated with increased risk for ventricular tachyarrhythmias, particularly when combined with conduction and/or repolarization abnormalities.</AbstractText> |
7,005 | Ablation of a Ca2+-activated K+ channel (SK2 channel) results in action potential prolongation in atrial myocytes and atrial fibrillation. | Small conductance Ca(2+)-activated K(+) channels (SK channels) have been reported in excitable cells, where they aid in integrating changes in intracellular Ca(2+) (Ca(2+)(i)) with membrane potential. We have recently reported the functional existence of SK2 channels in human and mouse cardiac myocytes. Moreover, we have found that the channel is predominantly expressed in atria compared to the ventricular myocytes. We hypothesize that knockout of SK2 channels may be sufficient to disrupt the intricate balance of the inward and outward currents during repolarization in atrial myocytes. We further predict that knockout of SK2 channels may predispose the atria to tachy-arrhythmias due to the fact that the late phase of the cardiac action potential is highly susceptible to aberrant excitation. We take advantage of a mouse model with genetic knockout of the SK2 channel gene. In vivo and in vitro electrophysiological studies were performed to probe the functional roles of SK2 channels in the heart. Whole-cell patch-clamp techniques show a significant prolongation of the action potential duration prominently in late cardiac repolarization in atrial myocytes from the heterozygous and homozygous null mutant animals. Moreover, in vivo electrophysiological recordings show inducible atrial fibrillation in the null mutant mice but not wild-type animals. No ventricular arrhythmias are detected in the null mutant mice or wild-type animals. In summary, our data support the important functional roles of SK2 channels in cardiac repolarization in atrial myocytes. Genetic knockout of the SK2 channels results in the delay in cardiac repolarization and atrial arrhythmias. |
7,006 | Management of atrial fibrillation--Part 2. | Many cardiologists prefer, especially in older patients, ventricular rate control plus warfarin rather than maintaining sinus rhythm with anti-arrhythmic drugs. Patients with chronic or paroxysmal AF at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio of 2.0 to 3.0. Patients with AF at low risk for stroke or with contraindications to warfarin should be treated with aspirin. |
7,007 | Catheter ablation - new developments in robotics. | Catheter ablation has become the curative treatment modality for various arrhythmias. Extending the indications for catheter ablation from simple supraventricular tachycardias to complex arrhythmias such as ventricular tachycardia or atrial fibrillation, the investigator faces prolonged procedure times, fluoroscopy exposure and the need for stable and reproducible catheter movement. Recently, remote-controlled robotic catheter ablation has emerged as a novel ablation concept to meet these requirements. This review describes the two available robotic ablation systems and summarizes their clinical applications and current human experience. |
7,008 | New antiarrhythmic drugs for the treatment of atrial fibrillation. | Atrial fibrillation (AF) is the most common arrhythmia requiring medical care, with a prevalence of almost 1% in the adult population. Particularly in the expanding elderly population, pharmacological therapy is and will continue to be the mainstay of AF therapy. Many currently used antiarrhythmic drugs have limited efficacy and cause cardiac and extracardiac toxicity. Thus, there is a continued need for development of new compounds with good efficacy and particularly with a favorable safety profile. Much emphasis is currently given to the development of so-called atrial-selective agents which target ion channels or proteins predominantly expressed in atrial myocardium. The rationale behind these compounds is to avoid unwanted effects on ionic currents on the ventricular site thus avoiding ventricular proarrhythmic effects. Alternatively, more conventional multichannel-blocking drugs are developed, for instance congeners of amiodarone. These molecules are designed to retain the electrophysiological efficacy of the mother compound while avoiding the extracardiac toxicity of this drug. The compounds which are far advanced in their clinical development are vernakalant ("atrial-selective") and dronedarone (multichannel-blocking). Preclinical and clinical findings of these substances are summarized. |
7,009 | Acute efficacy of low-dose human atrial natriuretic peptide monotherapy without loop diuretics for acute decompensated heart failure with left ventricular systolic dysfunction: a case report. | A 64-year-old man was admitted to our hospital with new-onset acute decompensated heart failure (ADHF). He had left ventricular systolic dysfunction and chronic atrial fibrillation with a rapid ventricular response. Initial treatment with low-dose recombinant human atrial natriuretic peptide (hANP) alone and no loop diuretics had an immediate effect on ADHF and left ventricular systolic dysfunction. This case demonstrates that low-dose hANP (0.01 microg/kg/min) monotherapy can be safe and effective for ADHF, with no loop diuretics being required during hospitalization. However, clinical trials will be needed to further evaluate the acute efficacy and safety of hANP monotherapy in patients with ADHF. |
7,010 | Recurrent acute pulmonary embolism and paroxysmal atrial fibrillation associated with subclinical hyperthyroidism. | Subclinical hyperthyroidism is an increasingly recognized entity that is defined as a normal serum free thyroxine and free triiodothyronine levels with a thyroid-stimulating hormone level suppressed below the normal range and usually undetectable. It has been reported that subclinical hyperthyroidism is not associated with coronary heart disease or mortality from cardiovascular causes but it is sufficient to induce arrhythmias including atrial fibrillation and atrial flutter. It has also been reported that increased factor X activity in patients with subclinical hyperthyroidism represents a potential hypercoagulable state. Elevated D-dimer levels have been reported in acute pulmonary embolism and it has also been reported that right ventricular overload and hypoxia in acute pulmonary embolism may lead to right ventricular myocardium injury reflected by elevated cardiac troponin levels too. We present a case of recurrent pulmonary embolism associated with subclinical hyperthyroidism, in an 81-year-old Italian woman. Also this case focuses attention on the importance of a correct evaluation of subclinical hyperthyroidism. |
7,011 | Cavopulmonary anastomosis improves left ventricular assist device support in acute biventricular failure. | Right ventricular failure during left ventricular assist device (LVAD) support can result in severe hemodynamic compromise with high mortality. This study investigated the acute effects of cavopulmonary anastomosis on right ventricular loading and LVAD performance in a model of severe biventricular failure.</AbstractText>LVAD support was performed by means of centrifugal pump implantation in 14 anesthetized dogs (20-30 kg) with severe biventricular failure obtained by ventricular fibrillation induction. Animals were randomized to be submitted to classical cavopulmonary anastomosis (Glenn shunt) or to control group and were maintained under LVAD support for 2h. Left and right atrial, right ventricular and systemic pressures were monitored, while total pulmonary flow was simultaneously recorded by transonic flowmeters located on the superior vena cava and pulmonary trunk. Blood gas and venous lactate determinations were also obtained.</AbstractText>Ventricular fibrillation maintenance resulted in acute LVAD performance impairment after 90 min in the control group, while animals with Glenn circuit maintained normal LVAD pump flow (55+/-13 ml kg(-1)min(-1) vs 21+/-4 ml kg(-1)min(-1), p<0.001) and better peripheral perfusion (blood lactate of 29+/-10 pg/ml vs 46+/-9 pg/ml, p<0.001). Left and right atrial pressures did not change significantly, while right ventricular pressure was lower in animals with Glenn circuit (13+/-3 mm Hg vs 22+/-8 mm Hg, p=0.005). Right ventricular unloading with Glenn shunt also resulted in superior total pulmonary flow (59+/-13 ml kg(-1)min(-1) vs 17+/-3 ml kg(-1)min(-1), p<0.001).</AbstractText>The concomitant use of cavopulmonary anastomosis during LVAD support in a model of severe biventricular failure limited right ventricular overloading and resulted in better hemodynamic performance.</AbstractText> |
7,012 | A note on a method for determining advantageous properties of an anti-arrhythmic drug based on a mathematical model of cardiac cells. | Regional hyperkalemia during acute ischemia may provoke cardiac arrhythmias such as ventricular fibrillation. Despite intense research efforts over the last decades, the problem of finding an efficient anti-arrhythmic drug without dangerous side effects is still open. One approach to analyze the effect of anti-arrhythmic drugs is to do simulations based on mathematical models of collections of cardiomyocytes. Such simulations have recently illuminated the pro-arrhythmic capability of well-established anti-arrhythmic drugs. The purpose of the present note is to introduce a method intended for computing advantageous properties of an anti-arrhythmic drug. For a given model of a normal and an ischemic cell, we introduce a drug as a vector of non-negative real numbers whose components are multiplied by individual terms representing specific ionic currents. The drug vector is computed such that the action potentials of the resulting drugged cells are as close as possible to the action potential of a normal (not drugged) cell. Numerical simulations based on the Luo-Rudy I model and the Hund-Rudy model show that the classical shortened action potential obtained due to hyperkalemia is prolonged by using the drug computed by this method. Furthermore, for both models a 2D collection of spatially coupled ischemic cells give arrhythmogenic solutions before the drug is applied, and stable solutions after the drug is applied. It is emphasized that we do not address the possibility of realizing a drug with the properties computed in this note. |
7,013 | Sudden cardiac death complicating alcohol septal ablation: a case report and review of literature. | Over the years, alcohol septal ablation has become an effective and well-accepted modality in the treatment of patients with hypertrophic obstructive cardiomyopathy refractory to standard medical therapy. Malignant tachyarrythmias infrequently complicates the procedure and are usually self-terminating. We describe a case of alcohol septal ablation complicated by sudden cardiac death occurring immediately following the procedure requiring prolonged resuscitative efforts with eventual complete recovery. We also discuss the pathophysiologic significance of this event in the setting of this cardiomyopathy and its relevance as a complication of the procedure. |
7,014 | Transcatheter closure of atrial septal defect in elderly patients with permanent atrial fibrillation. | The aim of this study is to evaluate the feasibility and efficacy of device closure of atrial septal defect (ASD) in elderly patients with permanent atrial fibrillation.</AbstractText>Little is known about the feasibility of device closure of ASD in those patients.</AbstractText>Nine consecutive patients (mean age 68.1 years) with permanent atrial fibrillation (>1 year persistent) underwent catheter closure using the Amplatzer septal occluder. Transthoracic echocardiography and plasma B-type natriuretic peptide (BNP) level were assessed before and at 24 hours; and 1, 3, and >6 months after the closure. Before the procedure, appropriate dose of warfarin was used in all, diuretics was used in 8/9. Same amount of medications were continued after the procedure.</AbstractText>ASD could be closed in all (mean device size 27.3 mm) without hemodynamic and thromboembolic complications. New York Heart Association (NYHA) functional classification was significantly improved in all patients after device closure. No hemodynamic and thromboembolic complications were observed during the follow-up period (mean 10.6 months). Although permanent atrial fibrillation did not change in all after the procedure, resting heart rate decreased from 76.2 +/- 16.0 to 68.3 +/- 13.2 beats/min (P = 0.015). There was statistically significant improvement in right ventricular/left ventricular diameter ratio (1.08 +/- 0.16 to 0.73 +/- 0.10, P = 0.008) and plasma BNP level (183.7 +/- 90.5 to 94.6 +/- 47.4 pg/mL, P = 0.008) after >6 months device closure.</AbstractText>Even in the patients complicated with permanent fibrillation, transcatheter closure of ASD can contribute to symptomatic improvement as well as cardiac geometric remodeling.</AbstractText>Copyright 2009 Wiley-Liss, Inc.</CopyrightInformation> |
7,015 | Experimental study of the relationship between perfluoro-octyl bromide emulsion and norepinephrine release in reperfusion arrhythmia: isolated guinea pig heart model. | Perfluoro-octyl bromide (PFOB), one of the perfluorochemical oxygen transporters, improved postischemic cardiac dysfunctions. Also norepinephrine (NE) is one of the important inducible factors on reperfusion arrhythmias (ventricular fibrillation [VF]). We used these methods to evaluate the relationship between PFOB emulsion and NE release on reperfusion arrhythmias.</AbstractText>The perfusion of isolated guinea pig hearts was employed: each of four groups of 6-7 hearts were used with Krebs-Henseleit solution (KHS) as control, and KHS with 5%, 15%, or 30% PFOB emulsion. The hearts were perfused in a constant pressure Langendorff model, stabilized for 30 min, followed by 30 min preischemia, then 30 min ischemia and 45 min reperfusion at normothermia.</AbstractText>PFOB emulsion dose-dependently limited VF and inhibited NE release in reperfusion. Only 30% PFOB emulsion showed the significant improvement of VF (p=0.05). In hemodynamic parameters, only 5% PFOB emulsion showed a significant decrease in reperfusion, but there was no difference in coronary flow rate (CFR). No differences among the four groups were demonstrated in cardiac oxygen metabolic parameters.</AbstractText>It was most likely that a high concentration of PFOB emulsion attenuated reperfusion arrhythmia by decreasing NE release.</AbstractText> |
7,016 | Effect of baroreflex stimulation using phenylephrine injection on ST segment elevation and ventricular arrhythmia-inducibility in Brugada syndrome patients. | Patients affected by Brugada syndrome (BrS) are at risk of sudden cardiac death specifically at rest, when vagal tone is high. The aim of our study was to assess whether a phenylephrine injection, which provokes a baroreflex stimulation, could induce modification of the ST segment elevation and ventricular arrhythmias.</AbstractText>Baroreflex test was performed with the administration of phenylephrine (2 microg/kg) to four highly symptomatic patients in a setting fully equipped for cardiac resuscitation. Phenylephrine injection induced a deep vagal stimulation with a decrease in the mean heart rate from 75 +/- 7 to 50 +/- 8 bpm and an increase in the mean systolic blood pressure from 141 +/- 14 to 204 +/- 46 mmHg. ST segment elevation was not modified and no ventricular arrhythmias were induced during the test.</AbstractText>Although phenylephrine injection induced a major alpha-adrenergic vasoconstriction followed by an arterial baroreflex, this test failed to provoke ventricular arrhythmias or modification of the ST segment elevation in BrS patients.</AbstractText> |
7,017 | Impact of cardiac rhythm on mitral valve area calculated by the pressure half time method in patients with moderate or severe mitral stenosis. | The pressure half-time (PHT) method has been widely used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS), in the belief that this simple method provides reliable information on true MVA. However, its limitation has been repeatedly recognized under different circumstances. The aim of this study was to evaluate the effect of cardiac rhythm on PHT-derived MVA calculation in relation to net atrioventricular compliance (C(n)).</AbstractText>Patients (n = 41) with rheumatic pure moderate or severe MS were consecutively recruited. Eighteen patients with sinus rhythm were allocated to group 1 and the remaining patients with chronic atrial fibrillation to group 2. MVA was obtained using the PHT method and by planimetry (considered the gold standard in this study). C(n) was calculated with a previously validated equation.</AbstractText>There were no differences between the 2 groups in terms of age, gender, left ventricular dimensions or ejection fraction, or transmitral pressure gradient. Left atrial volume index (134.6 +/- 106.7 vs 79.2 +/- 16.8 mL; P = .003) and C(n) (6.6 +/- 1.5 vs 4.7 +/- 1.2 mL/mm Hg; P < .001) were higher in group 2 than in group 1. Disagreement of MVA estimation by PHT compared with that by 2-dimensional planimetry was 8.0 +/- 19.2% for group 1 and -24.9 +/- 13.9% for group 2 (P = .002). In addition, the extent of disagreement of PHT-derived MVA compared with that by 2-dimensional planimetry was significantly correlated with C(n) (r(2) = 0.71, P < .001). MVA by the PHT method was estimated to be substantially higher in patients with C(n) values < 4 mL/mm Hg, most of whom were in sinus rhythm. Multivariate analysis confirmed the independent association of cardiac rhythm with discrepancy of PHT-derived MVA compared with that by planimetry.</AbstractText>Changes in cardiac rhythm with associated modifications of C(n) can alter the accuracy of the PHT method for estimating MVA. Given the limitation described here, 2-dimensional planimetry, not the PHT method, should be used as a primary echocardiographic tool for MVA calculation.</AbstractText> |
7,018 | Recent advances in cardiopulmonary resuscitation: cardiocerebral resuscitation. | Cardiocerebral resuscitation (CCR) is a new approach for resuscitation of patients with cardiac arrest. It is composed of 3 components: 1) continuous chest compressions for bystander resuscitation; 2) a new emergency medical services (EMS) algorithm; and 3) aggressive post-resuscitation care. The first 2 components of CCR were first instituted in 2003 in Tucson, Arizona; in 2004 in the Rock and Walworth counties of Wisconsin; and in 2005 in the Phoenix, Arizona, metropolitan area. The CCR method has been shown to dramatically improve survival in the subset of patients most likely to survive: those with witnessed arrest and shockable rhythm on arrival of EMS. The CCR method advocates continuous chest compressions without mouth-to-mouth ventilations for witnessed cardiac arrest. It advocates either prompt or delayed defibrillation, based on the 3-phase time-sensitive model of ventricular fibrillation (VF) articulated by Weisfeldt and Becker. For bystanders with access to automated external defibrillators and EMS personnel who arrive during the electrical phase (i.e., the first 4 or 5 min of VF arrest), the delivery of prompt defibrillator shock is recommended. However, EMS personnel most often arrive after the electrical phase -- in the circulatory phase of VF arrest. During the circulatory phase of VF arrest, the fibrillating myocardium has used up much of its energy stores, and chest compressions that perfuse the heart are mandatory prior to and immediately after a defibrillator shock. Endotracheal intubation is delayed, excessive ventilations are avoided, and early-administration epinephrine is advocated. |
7,019 | Cardiac resynchronization therapy and atrial fibrillation. | Cardiac resynchronization therapy (CRT) is an important advance for the treatment of end-stage heart failure (HF). About 15-50% of HF is complicated by atrial fibrillation (AF), associated with worsened outcomes. The presence of AF may interfere with optimal delivery of CRT due to competition with biventricular (BiV) capture by conducted beats. Pacing algorithms in newer devices may not ensure consistent CRT delivery during periods of rapid ventricular rates. Atrioventricular junction ablation with permanent pacing eliminates interference by conducted beats and provides complete BiV capture and is associated with improved outcomes. Catheter ablation of AF is another promising alternative to maintain sinus rhythm in patients with AF and HF. However, the optimal indications for CRT delivery for patients in this complex cohort remain to be assessed in randomized clinical trials. |
7,020 | Rapid conversion of persistent atrial fibrillation to sinus rhythm by intravenous AZD7009. | This randomized, double-blind trial compared cardioversion rates between AZD7009 infusion (15-minute 3.25 mg/min, 15-minute 4.4 mg/min, or 30-minute 3.25 mg/min) and placebo infusion (15 or 30 minutes) in patients with atrial fibrillation (AF) scheduled for DC cardioversion. One hundred sixty-eight patients were randomized, 167 received study treatment, and 159 were included in perprotocol analyses. The mean duration of current AF episode was 47 days (range, 0.8-92). In the AZD7009 30-minute 3.25 mg/min group, 21 of 42 patients converted within 90 minutes, compared with 7 of 39, 7 of 36, and 0 of 42 patients in the 15-minute 3.25 mg/min, 15-minute 4.4 mg/min, and combined placebo groups, respectively. Patients not converted within 90 minutes underwent DC cardioversion. In patients with AF episodes </=30 days, conversion rates with AZD7009 30-minute 3.25 mg/min and after placebo followed by DC cardioversion were 82% and 83%, respectively. AZD7009 was generally well tolerated. Mean QTc increased by 15% to 20% in the AZD7009 treatment groups. One patient experienced a ventricular tachyarrhythmia of 7 beats, with features of torsades de pointes. AZD7009 was associated with a 50% conversion rate in the best-dose group. In patients with AF episodes <or=30 days, the conversion rates after AZD1305 and placebo followed by DC cardioversion were observed to be similar. |
7,021 | Taser blunt probe dart-to-heart distance causing ventricular fibrillation in pigs. | The maximum distance between the heart and a model Taser stimulation dart, called the dart-to-heart distance, at which the Taser can directly cause ventricular fibrillation (VF), was measured in pigs. A 9-mm-long blunt probe was advanced snugly through the surrounding tissues toward the heart. Five animals [pig mass=61.2+/-6.23 standard deviation (SD) kg] for ten dart-to-heart distances where the Taser caused VF were tested. The dart-to-heart distances where the Taser caused VF of the first stimulation site ranged from 4 to 8 mm with average 6.2 mm+/-1.79 (SD) and of the second stimulation site ranged from 2 to 8 mm with average 5.4 mm+/-2.41 (SD). The results help inform the evolving discussion of risks associated with Tasers. |
7,022 | The left atrium, atrial fibrillation, and the risk of stroke in hypertensive patients with left ventricular hypertrophy. | The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study provided extensive data on predisposing factors, consequences, and prevention of atrial fibrillation (AF) in patients with hypertension and left ventricular (LV) hypertrophy. Randomized losartan-based treatment was superior to atenolol-based treatment for reducing new-onset AF and complications, especially stroke, associated with new-onset or pre-existing AF. Potential mechanisms of AF prevention by angiotensin receptor blockade supported by LIFE results include greater reduction in left atrial size and LV hypertrophy. Differential effects of antihypertensive treatment on the left atrium and left ventricle may help prevent AF and reduce risk of stroke associated with hypertensive heart disease. |
7,023 | Vortex filament dynamics in computational models of ventricular fibrillation in the heart. | In three-dimensional cardiac tissue, the re-entrant waves that sustain ventricular fibrillation rotate around a line of phase singularity or vortex filament. The aim of this study was to investigate how the behavior of these vortex filaments is influenced by membrane kinetics, initial conditions, and tissue geometry in computational models of excitable tissue. A monodomain model of cardiac tissue was used, with kinetics described by a three-variable simplified ionic model (3V-SIM). Two versions of 3V-SIM were used, one with steep action potential duration restitution, and one with reduced excitability. Re-entrant fibrillation was then simulated in three tissue geometries: a cube, a slab, and an anatomically detailed model of rabbit ventricles. Filaments were identified using a phase-based method, and the number, size, origin, and orientation of filaments was tracked throughout each simulation. The main finding of this study is that kinetics, initial conditions, geometry, and anisotropy all affected the number, proliferation, and orientation of vortex filaments in re-entrant fibrillation. An important finding of this study was that the behavior of vortex filaments in simplified slab geometry representing part of the ventricular wall did not necessarily predict behavior in an anatomically detailed model of the rabbit ventricles. |
7,024 | IK1 heterogeneity affects genesis and stability of spiral waves in cardiac myocyte monolayers. | Previous studies have postulated an important role for the inwardly rectifying potassium current (I(K1)) in controlling the dynamics of electrophysiological spiral waves responsible for ventricular tachycardia and fibrillation. In this study, we developed a novel tissue model of cultured neonatal rat ventricular myocytes (NRVMs) with uniform or heterogeneous Kir2.1expression achieved by lentiviral transfer to elucidate the role of I(K1) in cardiac arrhythmogenesis. Kir2.1-overexpressed NRVMs showed increased I(K1) density, hyperpolarized resting membrane potential, and increased action potential upstroke velocity compared with green fluorescent protein-transduced NRVMs. Opposite results were observed in Kir2.1-suppressed NRVMs. Optical mapping of uniformly Kir2.1 gene-modified monolayers showed altered conduction velocity and action potential duration compared with nontransduced and empty vector-transduced monolayers, but functional reentrant waves could not be induced. In monolayers with an island of altered Kir2.1 expression, conduction velocity and action potential duration of the locally transduced and nontransduced regions were similar to those of the uniformly transduced and nontransduced monolayers, respectively, and functional reentrant waves could be induced. The waves were anchored to islands of Kir2.1 overexpression and remained stable but dropped in frequency and meandered away from islands of Kir2.1 suppression. In monolayers with an inverse pattern of I(K1) heterogeneity, stable high frequency spiral waves were present with I(K1) overexpression, whereas lower frequency, meandering spiral waves were observed with I(K1) suppression. Our study provides direct evidence for the contribution of I(K1) heterogeneity and level to the genesis and stability of spiral waves and highlights the potential importance of I(K1) as an antiarrhythmia target. |
7,025 | Diacylglycerol kinase zeta inhibits G(alpha)q-induced atrial remodeling in transgenic mice. | Our previous study showed that diacylglycerol kinase zeta (DGKzeta), which degenerates diacylglycerol (DAG), inhibits ventricular structural remodeling and rescues activated G protein (alpha)q (G(alpha)q)-induced heart failure. However, whether DGKzeta inhibits atrial remodeling is still unknown.</AbstractText>This study aimed to elucidate the effects of DGKzeta on atrial remodeling.</AbstractText>A transgenic mouse (G(alpha)q-TG) with cardiac expression of activated G(alpha)q and a double transgenic mouse (G(alpha)q/DGKzeta-TG) with cardiac overexpression of DGKzeta and activated G(alpha)q were created.</AbstractText>During electrocardiogram (ECG) recording for 10 min, atrial fibrillation was observed in 5 of 11 anesthetized G(alpha)q-TG mice but not in any wild-type (WT) and G(alpha)q/DGKzeta-TG mice (P <.05). All of the ECG parameters measured were prolonged in the G(alpha)q-TG compared with WT mice. Interestingly, in G(alpha)q/DGKzeta-TG mice, although the PR and RR intervals were still prolonged, the P interval, QRS complex, and QT interval were not different from those in WT mice. In Langendorff-perfused hearts, the incidence of atrial tachyarrhythmia induced by rapid atrial pacing was greater in G(alpha)q-TG hearts than in G(alpha)q/DGKzeta-TG hearts (P <.05). Action potential duration prolongation and impulse conduction slowing were observed in G(alpha)q-TG atria compared with G(alpha)q/DGKzeta-TG atria. Dilatation of the left atrium with thrombus formation was observed in 9 G(alpha)q-TG hearts but not in any G(alpha)q/DGKzeta-TG hearts. Moreover, the degree of extensive interstitial fibrosis in the left atrium was greater in G(alpha)q-TG hearts than that in G(alpha)q/DGKzeta-TG hearts (P <.05).</AbstractText>These results show that DGKzeta inhibits G(alpha)q-induced atrial remodeling and suggest that DGKzeta is a novel therapeutic target for atrial fibrillation.</AbstractText> |
7,026 | Effects of simvastatin on cardiac neural and electrophysiologic remodeling in rabbits with hypercholesterolemia. | Significant cardiac neural and electrophysiologic remodeling occurs with hypercholesterolemia (HC). Whether simvastatin can reverse HC-induced remodeling is unclear.</AbstractText>The purpose of this study was to determine the mechanisms underlying the antiarrhythmic effects of statins.</AbstractText>Rabbits (N = 38) were fed HC chow (HC), standard chow (Control), HC chow followed by standard chow (Withdrawal), or HC chow and simvastatin (Statin) for 8 weeks. The hearts then were Langendorff-perfused for electrophysiologic studies. Nerves were identified by immunostaining of growth-associated protein-43 (GAP43) and tyrosine hydroxylase (TH). Action potential duration (APD) restitution in normal hearts with (N = 5) and without (N = 5) simvastatin therapy also was studied.</AbstractText>Serum cholesterol levels (mg/dL) were 1,855 +/- 533 in HC, 50 +/- 21 in Control, 570 +/- 115 in Withdrawal, and 873 +/- 112 in Statin groups (P <.001). Compared with HC (16,700 +/- 5,342; 12,200 +/- 3,878 microm(2)/mm(2)), the Statin group had significantly reduced GAP43-positive (10,289 +/- 3,393 microm(2)/mm(2), P = .03) and TH-positive (7,685 +/- 2,959 microm(2)/mm(2), P = .04) nerve density, respectively. APD was longer in HC rabbits than in controls (192 +/- 20 ms vs 174 +/- 17 ms; P <.03). Withdrawal and Statin groups had less APD prolongation than HC group. Statin group has less repolarization heterogeneity than HC group (P <.01). Statin therapy flattened the slope of APD restitution in normal hearts. Ventricular fibrillation was either induced or occurred spontaneously in 79% of hearts in HC, 20% in Control, and 66% in Withdrawal groups. However, there was no VF in hearts of Statin group (P <.001).</AbstractText>Simvastatin significantly reduced vulnerability to ventricular fibrillation via the mechanism of reduction of HC-induced neural and electrophysiologic remodeling.</AbstractText> |
7,027 | Comparison of beta blocker and digoxin alone and in combination for management of patients with atrial fibrillation and heart failure. | In patients with atrial fibrillation (AF) and heart failure (HF), beta blockers and digoxin reduce the ventricular rate, but controversy exists concerning how these drugs affect prognosis in this setting. This study compared the effects of beta blocker and digoxin on mortality in patients with both AF and HF. In a single-center institution, patients with AF and HF seen between January 2000 and January 2004 were identified and followed until September 2007. Of 1,269 consecutive patients with both AF and HF, 260 were treated with a beta blocker alone, 189 with beta blocker plus digoxin, 402 with digoxin alone, and 418 without beta blocker or digoxin (control group). During a follow-up of 881+/-859 days, 247 patients died. Compared with the control group, treatment with beta blocker was associated with a decreased mortality (relative risk=0.58, 95% confidence interval 0.40 to 0.85, p=0.005 for beta blocker alone and 0.59, 95% confidence interval 0.40 to 0.87, p=0.008 for beta blocker plus digoxin). By contrast, treatment with digoxin alone was not associated with a better survival (relative risk=0.97, 95% confidence interval 0.73 to 1.30, p=NS). Results remained significant after adjustment for potential confounders and similar when we considered, separately, HF with permanent or nonpermanent AF, presence or absence of coronary disease, and patients with decreased or preserved systolic function. In conclusion, in unselected patients with AF and HF, treatments with beta blocker alone or with beta blocker plus digoxin are associated with a similar decrease in the risk of death. Digoxin alone is associated with a worse survival chance, similar to that of patients without any rate control treatment. |
7,028 | Effect of catheter ablation for isolated paroxysmal atrial fibrillation on longitudinal and circumferential left ventricular systolic function. | Isolated paroxysmal atrial fibrillation (AF) is commonly associated with left ventricular (LV) diastolic dysfunction but normal radial systolic contraction. We aim to investigate LV systolic function more precisely using 2-dimensional strain technique in patients with isolated paroxysmal AF and to evaluate evolution of longitudinal, circumferential, and radial (or transverse) strain components after catheter ablation of AF. Thirty patients with isolated paroxysmal AF were investigated by echocardiographic studies before and at 1-day, 1-month, 6-month, and 12-month intervals after radiofrequency ablation. Left heart dimensions and LV systolic and diastolic functions were evaluated at each time interval. LV systolic function was quantified by LV ejection fraction and by 2-dimensional strain evaluation, giving regional and global longitudinal, circumferential, transverse, and radial peak of percentage deformation. Patients with AF were compared with 30 control subjects, paired by age and by sex. Before AF ablation, LV ejection fraction, transverse and radial strains were not significantly different from control subjects. By contrast, global longitudinal and circumferential strains were significantly lower than controls (-17.7%+/-2.4% vs -21.5%+/-2.0% [p<0.01] and -16.0%+/-2.9% vs -20.7%+/-3.4% [p<0.01], respectively). At the end of follow-up, global longitudinal and circumferential strains were significantly improved (-20.8%+/-2.6% vs -17.7%+/-2.4% (p<0.01) and -18.5%+/-3.1% vs -16.0%+/-2.9% [p<0.05], respectively). Global longitudinal strain was not significantly different from normal control subjects at the end of follow-up. In conclusion, this prospective study demonstrates (1) the existence of early longitudinal and circumferential LV systolic function abnormalities in patients with isolated paroxysmal AF but normal ejection fraction and (2) reverse remodeling of these abnormalities after AF ablation. |
7,029 | Ventricular fibrillation with prominent early repolarization associated with a rare variant of KCNJ8/KATP channel. | Early repolarization in the inferolateral leads has been recently recognized as a frequent syndrome associated with idiopathic ventricular fibrillation (VF). We report the case of a patient presenting dramatic changes in the ECG in association with recurrent VF in whom a novel genetic variant has been identified.</AbstractText>This young female (14 years) was resuscitated in 2001 following an episode of sudden death due to VF. All examinations including coronary angiogram with ergonovine injection, MRI, and flecainide or isoproterenol infusion were normal. The patient had multiple (>100) recurrences of VF unresponsive to beta-blockers, lidocaine/mexiletine, verapamil, and amiodarone. Recurrences of VF were associated with massive accentuation of the early repolarization pattern at times mimicking acute myocardial ischemia. Coronary angiography during an episode with 1.2 mV J/ST elevation was normal. Isoproterenol infusion acutely suppressed electrical storms, while quinidine eliminated all recurrences of VF and restored a normal ECG over a follow-up of 65 months. Genomic DNA sequencing of K(ATP) channel genes showed missense variant in exon 3 (NC_000012) of the KCNJ8 gene, a subunit of the K(ATP) channel, conferring predisposition to dramatic repolarization changes and ventricular vulnerability.</AbstractText> |
7,030 | [Screening for asymptomatic left ventricular systolic dysfunction in high-risk patients. Preliminary experience with a program based on the use of ECG and natriuretic peptide]. | Patients with asymptomatic left ventricular systolic dysfunction (ALVSD) have an increased risk of heart failure (HF) and a worse life expectancy. Since valuable therapies may prevent such dismal evolution, screening programs for ALVSD have recently been advocated to detect as early as possible such ominous condition. Echocardiography represents the gold standard for the assessment of ALVSD but its indiscriminate use in screening programs is impractical. Clinical multivariate risk assessment associated with ECG and serum brain natriuretic peptide (BNP) may be a feasible strategy to screen ALVSD. We prospectively sought to investigate the feasibility and effectiveness of a screening program for ALVSD based on ECG and BNP used in a hierarchical sequence in patients at high risk for HF.</AbstractText>Patients > or =55 years old with > or =2 risk factors for HF or > or =70 years old with > or =1 risk factor for HF entered the study performing sequentially ECG, BNP and echocardiographic evaluation. ALVSD was defined as a left ventricular ejection fraction < or =50%.</AbstractText>Thirty-three of 122 enrolled patients (27%) had ALVSD. They were older, presented more frequently a history of chemotherapy exposure, had often bundle branch block and higher BNP levels. No patient without any major abnormalities (atrial fibrillation, left ventricular hypertrophy, STT alterations of ischemic/strain origin, pathologic Q wave, bundle branch block) on ECG (n=31, 24.4%) had ALVSD. Among the 91 patients with abnormal ECG, ALVSD was observed in 33 (36%). The area under the receiver operating characteristic curve to detect ALVSD by BNP was 0.86 (confidence interval 0.79-0.94, p<0.0001) and BNP values of > or =43 pg/ml showed a sensitivity and a specificity of 94% and 57%, respectively. The proposed screening program was able to identify 95% (31/33) of patients with ALVSD saving 53% of echocardiographic examinations with a substantial reduction of the costs to diagnose ALVSD.</AbstractText>Our prospective investigation confirms that ECG and BNP may be useful in detecting ALVSD in high-risk patients. A cost-effective screening program based on such simple and low-cost diagnostic tests might be employed for the prevention of HF in primary and secondary prevention programs in high-risk patients.</AbstractText> |
7,031 | Developmental basis for electrophysiological heterogeneity in the ventricular and outflow tract myocardium as a substrate for life-threatening ventricular arrhythmias. | Reentry is the main mechanism of life-threatening ventricular arrhythmias, including ventricular fibrillation and tachycardia. Its occurrence depends on the simultaneous presence of an arrhythmogenic substrate (a preexisting condition) and a "trigger," and is favored by electrophysiological heterogeneities. In the adult heart, electrophysiological heterogeneities of the ventricle exist along the apicobasal, left-right, and transmural axes. Also, conduction is preferentially slowed in the right ventricular outflow tract, especially during pharmacological sodium channel blockade. We propose that the origin of electrophysiological heterogeneities of the adult heart lies in early heart development. The heart is formed from several progenitor regions: the first heart field predominantly forms the left ventricle, whereas the second heart field forms the right ventricle and outflow tract. Furthermore, the embryonic outflow tract consists of slowly conducting tissue until it is incorporated into the ventricles and develops rapidly conducting properties. The subepicardial myocytes and subendocardial myocytes run distinctive gene programs from their formation onwards. This review discusses the hypothesis that electrophysiological heterogeneities in the adult heart result from persisting patterns in gene expression and function along the craniocaudal and epicardial-endocardial axes of the developing heart. Understanding the developmental origins of electrophysiological heterogeneity contributing to ventricular arrhythmias may give rise to new therapies. |
7,032 | Death caused by simultaneous subacute stent thrombosis of sirolimus-eluting stents in left anterior descending artery and left circumflex artery. | Simultaneous drug-eluting stent thrombosis in multivessel disease is a low incidence, but could cause lethal clinical event. We report a case with death caused by simultaneous subacute stent thrombosis of sirolimus-eluting stents in the proximal left anterior descending artery and in the proximal left circumflex artery. |
7,033 | Revelation of Brugada electrocardiographic pattern during a febrile state. | The prevalence of the Brugada-type ECG and its natural history are still unclear. The Brugada syndrome is usually identified by a characteristic Brugada-type ECG that consists of ST elevation of a coved type in the precordial leads V1 to V3 and ventricular fibrillation that can lead to sudden cardiac death, although affected individuals may have a normal ECG. Mutations in the cardiac sodium channel gene SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent Na+ channel (Na(v)1.5), are identified in 15-30% of patients with Brugada syndrome. Most SCN5A mutations lead to a 'loss-of-function' phenotype, reducing the Na+ current during the early phases of the action potential. Several nongenetic factors have been mentioned in the literature as possible inductors of the ECG pattern resembling Brugada syndrome. As such, a Brugada-type ECG may appear in some patients during febrile states and in those who are under the influence of cocaine and pharmaceutical drugs that have a sodium channel-blocking effect. It has been also reported that chest pain and ST elevation Brugada pattern occur during febrile states. We present a case of revelation of Brugada pattern in a 61-year-old Italian man complaining of pain in the left hipocondrium during a febrile state. Also this report confirms that Brugada pattern should be considered as one of differential diagnoses when we examine the patients during a febrile state. |
7,034 | Functional polymorphisms in ACE and CYP11B2 genes and atrial fibrillation in patients with hypertensive heart disease. | The activated renin-angiotensin-aldosterone system has been reported to play an important role in the pathogenesis of atrial fibrillation (AF). We hypothesized that functional genetic variations of angiotensin-converting enzyme (ACE) and CYP11B2 genes may influence the susceptibility to AF in patients with hypertensive heart disease.</AbstractText>The I/D polymorphism of ACE was detected by polymerase chain reaction (PCR), and the -344C/T polymorphism of the CYP11B2 gene was detected using PCR and subsequent cleavage by HaeIII restriction endonuclease.</AbstractText>The overall distribution of ACE I/D genotypes in patients with and without AF was significantly different (p=0.001). The frequency of the DD genotype was significantly higher in patients with AF than in patients without AF (20.6% vs. 8.1%, OR 2.94, 95% CI 1.64-5.26, p<0.001). The frequency of the D allele was significantly higher in the AF group than in the non-AF group (p=0.001). After adjustment for age and left atrial dimension, multivariable analysis showed that the DD genotype of the ACE gene was an independent risk factor for AF in patients with hypertensive heart disease. No relationship between -344 C/T CYP11B2 polymorphism and AF was found in this cohort.</AbstractText>Our study suggests that ACE I/D polymorphism is associated with AF and the DD genotype may be an independent predictive factor for AF in patients with hypertensive heart disease.</AbstractText> |
7,035 | Prolonged closed cardiac massage using LUCAS device in out-of-hospital cardiac arrest with prolonged transport time. | Saving more human lives through more effective reanimation measures is the goal of the new international guidelines on cardiopulmonary resuscitation as the decisive aspect for survival after cardiovascular arrest is that basic resuscitation should start immediately. According to the updated guidelines, the greatest efficacy in cardiac massage is only achieved when the right compression point, an adequate compression depth, vertical pressure, the correct frequency, and equally long phases of compression and decompression are achieved. The very highest priority is placed on restoring continuous circulation. Against this background, standardized continuous chest compression with active decompression has contributed to a favorable outcome in this case. The hydraulically operated and variably adjustable automatic Lund University Cardiac Arrest System (LUCAS) device (Jolife, Lund, Sweden) undoubtedly meets these requirements. This case report describes a 44-year-old patient who - approximately 15 min after the onset of clinical death due to apparent ventricular fibrillation - received cardiopulmonary resuscitation, initially by laypersons and then by the emergency medical team (manual chest compressions followed by situation-adjusted LUCAS compressions). Sinus rhythm was restored after more than 90 min of continuous resuscitation, with seven defibrillations. Interventional diagnostic workup did not reveal a causal morphological correlate for the condition on coronary angiography. After a 16-day period of hospital convalescence, with preventive implantation of an implantable cardioverter defibrillator and several weeks of rehabilitation, the patient was able to return home with no evidence of health impairment. |
7,036 | Prolonged Mild-to-Moderate Hypothermia for Refractory Intracranial Hypertension. | Therapeutic hypothermia is an emerging therapy for brain injury and cerebral edema. Hypothermia is known to reduce death and neurologic morbidity in survivors of cardiac arrest from ventricular fibrillation. Traumatic brain injury (TBI) trials studies of short-term hypothermia (24 to 48hours) have had conflicting results. Recent evidence however suggests prolonged hypothermia (48 hours to 14 days) may be beneficial for TBI and select cases of nontraumatic brain injury especially when the duration of cerebral edema and intracranial hypertension is expected to last longer than 24 hours.</AbstractText>A 43-year-old female presented with a Fisher grade 4 aneurysmal (anterior communicating artery) subarachnoid hemorrhage. The patient was comatose upon transfer to our hospital, was intubated, and had immediate aneurysm coiling. The patient had a right external ventricular drain (EVD) placed for acute hydrocephalus and intracranial pressure (ICP) monitoring. The patient developed severe vasospasm of several intracranial vessels requiring angioplasty on two consecutive days, and hypertensive, hypervolemic, hemodilution therapy (HHH). On the ninth day, ICP went above 20mmHg and computed tomography (CT) showed global cerebral edema. For the next 17 days, the patient had refractory intracranial hypertension, requiring sedation, neuromuscular blockade, hyperosmolar therapy (3% infusion, and 23.4% saline boluses), thiopental coma with burst suppression, and hypothermia (31 to 34C). Hypothermia continued for a total of 14 days before ICP and edema on CT normalized.</AbstractText>We report the first case of prolonged therapeutic hypothermia over a total of 14days to control nontraumatic brain injury-related refractory intracranial pressure and global cerebral edema. More studies are needed comparing clinical outcomes and complication rates between short duration and prolonged hypothermia for brain injury.</AbstractText> |
7,037 | Banding and Step-Stair Artifacts on the Cardiac-CT Caused By Pseudo-Ectopic Beats. | Step-stair and banding artifacts may result from irregular ventricular rhythm caused by atrial fibrillation or premature ectopic ventricular contractions. In the case reported here, severe banding and misalignment artifacts occurred due to electrocardiographic noise mimicking ectopic beats. Severe EKG noise or pseudo-ectopic beats may cause rare but serious artifacts during cardiac-CT acquisition. Vendor-provided software for correcting ectopic beats can be used to remove pseudo-ectopic beats and eliminate artifacts caused by the EKG noise. All efforts should be made to prevent this kind of problem from happening in the first place. |
7,038 | Bionic cardiology: exploration into a wealth of controllable body parts in the cardiovascular system. | Bionic cardiology is the medical science of exploring electronic control of the body, usually via the neural system. Mimicking or modifying biological regulation is a strategy used to combat diseases. Control of ventricular rate during atrial fibrillation by selective vagal stimulation, suppression of ischemia-related ventricular fibrillation by vagal stimulation, and reproduction of neurally commanded heart rate are some examples of bionic treatment for arrhythmia. Implantable radio-frequency-coupled on-demand carotid sinus stimulators succeeded in interrupting or preventing anginal attacks but were replaced later by coronary revascularization. Similar but fixed-intensity carotid sinus stimulators were used for hypertension but were also replaced by drugs. Recently, however, a self-powered implantable device has been reappraised for the treatment of drug-resistant hypertension. Closed-loop spinal cord stimulation has successfully treated severe orthostatic hypotension in a limited number of patients. Vagal nerve stimulation is effective in treating heart failure in animals, and a small-size clinical trial has just started. Simultaneous corrections of multiple hemodynamic abnormalities in an acute decompensated state are accomplished simply by quantifying fundamental cardiovascular parameters and controlling these parameters. Bionic cardiology will continue to promote the development of more sophisticated device-based therapies for otherwise untreatable diseases and will inspire more intricate applications in the twenty-first century. |
7,039 | Sudden cardiac arrest in apical hypertrophic cardiomyopathy. | We present two cases of cardiac arrest, presumably attributable to apical hypertrophic cardiomyopathy(HCM). The first case was a 37-year-old Asian man known to have an apical HCM and was successfully resuscitated from an "out of hospital" ventricular fibrillation arrest. He underwent an electrophysiological study that was unable to induce tachyarrhythmias, which may not be surprising. He did receive an automated internal cardioverter defibrillator (AICD) in compliance with his class I indication for an implantable defibrillator. The second patient was an 86-year-old Caucasian woman with a cardiac history significant for apical HCM, coronary artery disease, diastolic heart failure, and monomorphic ventricular tachycardia. She underwent electrophysiological testing for frequent dizziness and monomorphic ventricular tachycardia of a right ventricular origin was induced. She received an AICD for sudden cardiac death prevention. Though lethal ventricular arrhythmias have been reported in patients with apical HCM, the prevailing consensus is that the prognosis of apical HCM is benign. Whether these accounts are truly exceptional occurrences for this rare and conventionally regarded benign condition or whether they represent an under-appreciated risk for sudden cardiac arrest is an intriguing question. |
7,040 | Choroid plexus papilloma in children: Diagnostic and surgical considerations. | Choroid plexus papilloma (CPP) is a benign neoplasm that arises from the ventricular choroid plexus. The clinical features, radiological characteristics, and treatment have been discussed in this study for a pediatric population.</AbstractText>Over an eight-year period, seven pediatric (≤12 years) CPP patients were treated. Tumors were located in the lateral ventricle (n = 4), IVth ventricle (n = 2), and in both the lateral and IIIrd ventricles (n = 1). The patients presented predominantly with features of raised intracranial pressure. Total microsurgical excision was carried out in all cases.</AbstractText>There was complete relief of symptoms at follow-up in six patients. A 2.5 year-old child with a large trigonal CPP with hydrocephalus leading to complete visual impairment, died due to postoperative hypokalemia that caused ventricular fibrillation. One of our patients required a postoperative, permanent CSF diversion procedure while another required a subduroperitoneal shunt for persisting postoperative subdural CSF collection.</AbstractText>Coagulation of the tumor under constant irrigation to shrink and excise it in toto, avoids excessive bleeding during surgery. The vascular pedicle supplying the tumor should be adequately dealt with during the last part of tumor removal as retraction of a bleeding pedicle may result in ventricular hemorrhage and brain edema. Following surgery, an external ventricular drain for three days helps in preventing the development of acute hydrocephalus in lateral ventricular lesions, and the color of the drained CSF gives an estimate of the ventricular hemostasis achieved. Total excision is usually possible in these cases with excellent postoperative outcomes.</AbstractText> |
7,041 | Differential diagnosis of non-atherosclerotic left main coronary artery stenosis. | A left main coronary artery (LMCA) stenosis without any atherosclerotic changes elsewhere in the coronary artery tree is a rare finding, and some uncommon reasons for luminal narrowing should be considered. An unusual case of non-atherosclerotic LMCA stenosis is reported.A middle-aged patient presented with acute myocardial infarction. An immediate coronary angiography was ordered and revealed a subtotal mid LMCA stenosis. A drug-eluting stent was successfully implanted in the LMCA.Operative revascularisation was recommended. Routine surgery was performed and surprisingly revealed an extended mass of a mediastinal tumour surrounding the aortic root. Histopathological examination of the tumour revealed a poorly differentiated squamous cell carcinoma.Postoperatively, the patient was treated with chemotherapy (carboplatin and docetaxel). Five years after the first admission to our hospital, the patient died as a result of ventricular fibrillation.The differential diagnosis of non-atherosclerotic LMCA stenoses is discussed. |
7,042 | Internet diagnosis of digitalis toxicity. | A 65-year-old male with an ischaemic cardiomyopathy and an implantable cardioverter defibrillator got a shock at home. A web-based monitoring system was used to check his device, and the interrogation showed that he had had several episodes of ventricular fibrillation and new onset of complete heart block that required back-up pacing by his defibrillator. The combination of enhanced automaticity (frequent premature ventricular complexes and ventricular arrhythmias) and impaired conduction (heart block) are the hallmarks of digitalis toxicity. Paramedics were called and the patient was brought to the emergency room where he was confirmed to have digitalis toxicity and was quickly treated with digoxin-specific Fab antibody fragments. Web-based monitoring systems helped in the diagnosis of this potentially lethal drug toxicity. |
7,043 | Propafenone induced Brugada-like ECG changes mistaken as acute myocardial infarction. | Brugada syndrome is one of the important causes of sudden cardiac death in young adults. The condition is associated with typical electrocardiogram (ECG) changes in anteroseptal leads V1 and V2 that can be unmasked by various medications, electrolyte disturbances, and even by the febrile state in susceptible individuals. The case history is reported of a patient with atrial flutter and atrial fibrillation who developed Brugada-like ECG changes when treated with propafenone. He was mistakenly diagnosed as having acute myocardial infarction when he presented to the emergency room with acute precordial chest pain. Cardiac catheterisation revealed normal coronary arteries and normal left ventricular systolic function. A review of previous ECGs showed the temporal relationship of ECG changes to initiation of propafenone a few years earlier. The ECG changes resolved with discontinuation of propafenone and re-emerged when he was rechallenged with oral propafenone. This case highlights the importance of recognising the characteristic ECG changes of Brugada syndrome and being able to differentiate them from those of acute myocardial infarction and other conditions manifesting with similar changes. |
7,044 | Current approaches to cardiopulmonary resuscitation. | Cardiac arrest occurs when there is abrupt cessation of effective pumping activity of the heart. Among the likely causes are ventricular asystole (electrical or mechanical), pulseless ventricular tachycardia or ventricular fibrillation. Clinically this may present as 'sudden cardiac death'. |
7,045 | Effectiveness of a simulation-based medical student course on managing life-threatening medical conditions. | To assess the competency and the comfort level of medical students in lifesaving skills after a simulation-based training session and then determine skill retention after 1 year.</AbstractText>Prospective observational before-after case series of medical students entering the third year. Each student participated in a half-day "How to Save a Life" course. The course consisted of a half-hour lecture on lifesaving skills followed by small group simulation-based skill sessions. Critical resuscitation actions were reviewed and demonstrated by the instructor using case-based scenarios and mannequins. The emergency medicine faculty and residents evaluated individual students' performance of clinical skill using a standardized checklist at each skill station. Each checklist specified the critical actions necessary to perform the procedure properly. Outcome measures included global competency and level of comfort questionnaire for each skill, using a 5-point Likert scale, with 1 being "strongly disagree" and 5 "strongly agree." Retention of lifesaving skills was assessed approximately 1.5 years later using a subset of the original group of the third year medical students. Without prior notification, students were assessed on the same skills using the same scenarios and outcome measures. Comparison of competency and level of comfort data between the initial group and the follow-up group were analyzed using descriptive statistics.</AbstractText>One hundred fifteen third year students participated in the initial training program. Initial demographic information was available on 104 students and revealed that 96% of the students had previous experience with basic life support. After the initial training course, all students were rated as competent in all procedures. In the retention group, the proportion of students achieving competence in each procedure ranged from 47% to 100%. The level of comfort decreased during the interval period.</AbstractText>A short course in simulation-based life-saving clinical skills is an effective means to teach the third year medical students. We observed a decline in competency over time for recognition of ventricular fibrillation, defibrillation, airway management, and management of a choking child. Cardiopulmonary resuscitation and automatic external defibrillator competency did not decrease over time.</AbstractText> |
7,046 | Consequences of Atrial or Ventricular Tachypacing on the Heat Shock Proteins (HSP) level of Expression and Phosphorylation. | Uncontrolled atrial fibrillation (AF) results in complex changes in the cardiomyocyte electrical and contractile functioning that promote atrial remodeling and the continuation of AF. Recently there has been a growing interest in understanding the role of heat shock proteins (HSPs), which are cytoprotective molecular chaperones, in the pathophysiology of AF. Several groups have examined HSP expression in patients with AF but have yielded mixed results. To allow for better consistency and reproducibility between subjects, we utilized canine models to reproduce AFpromoting conditions to better investigate the role of HSPs in the pathophysiology of AF.</AbstractText>AF promoting conditions were simulated in canine models with fifteen adult mongrel dogs (20.6 to 36.0 kg) divided into three groups: (1) Control (n=5), (2) two week ventricular tachypacing (VTP) induced congestive heart failure (CHF) (n=5), and (3) one week atrial tachypacying (ATP) (n=5). Quick frozen right atrial free wall tissue samples were used for protein isolation and were analyzed via Western blotting with data was expressed as a relative ratio and were analyzed using a two-tailed, unpaired ttest and significance was set at p < 0.05. The expression levels of HSP 90, 70, and 25 were studied along with the phosphorylation status of HSP27 at serine-78.</AbstractText>We first examined the effects of the ATP and CHF heart models on the expression of a select group of HSPs via Western Blot. We found that there was no significant difference in levels of expression of HSP 90, 70, or 25 when either ATP or CHF models were compared to control canines. The phosphorylation status of HSP27 was significantly decreased in the CHF canine model when compared to control (p < 0.0111) and it tended towards a decrease in the ATP canine model when compared to control (p=0.0923).</AbstractText>This study showed that even though the expression levels of HSPs may remain constant, there are protein phosphorylation and dephosphorylation events that occur in AF that may have important consequences in its pathophysiology. It is therefore necessary to investigate the full scale of HSP modifications during AF and AF-promoting conditions.</AbstractText> |
7,047 | Initial cardiac rhythm correlated to emergency department survival. | This study attempted to correlate the initial cardiac rhythm and survival from prehospital cardiac arrest, as a secondary end-point.</AbstractText>Prospective, randomized, double-blinded clinical intervention trial where bicarbonate was administered to 874 prehospital cardiopulmonary arrest patients in prehospital urban, suburban, and rural emergency medical service environments.</AbstractText>This group's manifested an overall survival rate of 13.9% (110 of 793) of prehospital cardiac arrest patients. The most common presenting arrhythmia was ventricular fibrillation (VF) (45.0%), asystole (ASY) (34.4%), and pulseless electrical activity (PEA) (15.7%). Less commonly found were normal sinus rhythm (NSR) (1.8%), other (1.8%), ventricular tachycardia (VT) (0.6%), and atrioventricular block (AVB) (0.5%) as prearrest rhythms. The best survival was noted in those with a presenting rhythm of AVB (57.1%), VT (33.3%), VF (15.7%), NSR (14.3%), PEA (11.2%), and ASY (11.1%) (p = 0.02). However, there was no correlation between the final cardiac rhythm and outcome, other than an obvious end-of-life rhythm.</AbstractText>The most common presenting arrhythmia was VF (45%), while survival is greatest in those presenting with AVB (57.1%).</AbstractText> |
7,048 | [Histochemical study of the myocardium structure in the heart contusion]. | The experimental modeling of heart contusion which was accompanied by ventricular fibrillation development was performed in Wistar rats, with the electrocardiographic study and subsequent histological and histochemical examination of the myocardium samples. Following heart contusion, acute circulatory disturbances, muscle fiber fragmentation, cardiomyocyte overcontraction or relaxation were detected in the myocardium. Also, the increase of total and intracellular calcium ion content in the myocardium was demonstrated. It is suggested that the mechanism of ventricular fibrillation development after heart contusion is associated with the increase of calcium concentration in both the cardiomyocytes and intercellular spaces leading to uncoordinated cardiac contractions. |
7,049 | The cognitive basis of effective team performance: features of failure and success in simulated cardiac resuscitation. | Despite a body of research on teams in other fields relatively little is known about measuring teamwork in healthcare. The aim of this study is to characterize the qualitative dimensions of team performance during cardiac resuscitation that results in good and bad outcomes. We studied each team's adherence to Advanced Cardiac Life Support (ACLS) protocol for ventricular fibrillation/tachycardia and identified team behaviors during simulated critical events that affected their performance. The process was captured by a developed task checklist and a validated team work coding system. Results suggest that deviation from the sequence suggested by the ACLS protocol had no impact on the outcome as the successful team deviated more from this sequence than the unsuccessful team. It isn't the deviation from the protocol per se that appears to be important, but how the leadership flexibly adapts to the situational changes with deviations is the crucial factor in team competency. |
7,050 | Potential application of late sodium current blockade in the treatment of heart failure and atrial fibrillation. | The cardiac action potential consists of the sequential activation of various ion channels in a precisely orchestrated manner. Pathologic alterations of ion channel currents disrupt this coordinated behavior and have been linked to arrhythmias, such as atrial fibrillation, as well as to heart failure. The late sodium current is increased in the ventricular myocytes in patients with heart failure and can result in contractile dysfunction. The most likely mechanism whereby elevated intracellular Na+ levels may lead to heart failure is through calcium overload. Sodium channel blockade is a proven strategy in the treatment of atrial fibrillation. Although all class I antiarrhythmic drugs inhibit the sodium current, ranolazine has been shown to be a more specific and potent blocker of the late sodium current. In clinical trials, ranolazine has significantly decreased episodes of nonsustained ventricular tachycardia and supraventricular tachycardia as compared with placebo. |
7,051 | Cerebral desaturation during cardiac arrest: its relation to arrest duration and left ventricular pump function. | To determine the impact of brief periods of cardiac arrest (CA) on regional cerebral oxygen saturation (rSO2) in patients with low left ventricular ejection fraction (LVEF <30%).</AbstractText>Prospective observational study.</AbstractText>Cardiac surgery room at a university hospital.</AbstractText>Seventy-seven consecutive patients undergoing elective implantation of a cardioverter/defibrillator in monitored anesthesia care. According to preoperative assessments, left ventricular function was classified as normal (LVEF >50%), moderately impaired (LVEF 30%-50%), or severely reduced (LVEF <30%).</AbstractText>None.</AbstractText>rSO2 was determined during threshold testing with concomitant induction of CA. In patients with LVEF <30%, mean baseline rSO2 (59%) was already below the lower range of normal despite normal arterial blood pressure, heart rate, and arterial oxygen saturation. rSO2 increased by 6% after 6 L/min oxygen insufflation (p < 0.05) and dropped again in each group after CA, reaching a nadir after successful defibrillation. Patients with LVEF <30% and baseline rSO2 <63% exhibited the lowest values. They also showed the highest incidence (11%) of critical cerebral desaturations (i.e., >20% drop from baseline or rSO2 value <50%). rSO2 in patients with LVEF <30% was always below that determined in patients with LVEF >30% (p < 0.05). There was a strong correlation between rSO2 values before CA and rSO2 nadir (p < 0.05). The drop in rSO2 was only moderately related to the brief CAs (p < 0.05).</AbstractText>These findings demonstrate that severely compromised left ventricular pump function is associated with diminished rSO2. As these patients seem to be more susceptible to critical desaturations, they may be prone to severe tissue hypoxemia unless adequate oxygen delivery is reestablished rapidly. This may contribute to the poor neurologic outcome after successful resuscitation in patients with LVEF <30%.</AbstractText> |
7,052 | Arrhythmias and heart rate variability during and after therapeutic hypothermia for cardiac arrest. | To evaluate the effects of therapeutic hypothermia (HT) of 33 degrees C after cardiac arrest (CA) on cardiac arrhythmias, heart rate variability (HRV), and their prognostic value.</AbstractText>Prospective, comparative substudy of a randomized controlled trial of mild HT after out-of-hospital CA, the European Hypothermia After Cardiac Arrest study.</AbstractText>Intensive care unit of a tertiary referral hospital (Helsinki University Hospital).</AbstractText>Seventy consecutive adult patients resuscitated from out-of-hospital ventricular fibrillation were randomly assigned either to therapeutic HT of 33 degrees C or normothermia.</AbstractText>Patients randomized to HT were cooled with an external cooling device for 24 hours and then allowed to rewarm slowly during 12 hours. In the normothermia group, the core temperature was kept <38 degrees C by antipyretics and physical means. All patients received standard intensive care for at least 2 days.</AbstractText>Twenty-four hour ambulatory electrocardiography recordings were performed at 0-24 hours, at 24-48 hours, and at 14 days. The clinical outcome was assessed at 6 months after CA. The occurrence of premature ventricular beats was increased in the HT-treated group during the first two recordings, with no difference in the number of ventricular tachycardia or ventricular fibrillation episodes. All HRV values were significantly higher during the HT (p < 0.01), but no differences were observed 2 weeks later. In multivariate analysis, only shorter delay to restoration of spontaneous circulation (p = 0.009) and the sd of individual normal-to-normal intervals >100 msec of the 24-48-hour recording in the HT group (p = 0.018) predicted good outcome.</AbstractText>The use of therapeutic HT of 33 degrees C for 24 hours after CA was not associated with an increase in clinically significant arrhythmias. Preserved 24 to 48-hour HRV may be a predictor of favorable outcome in patients with CA treated with HT.</AbstractText> |
7,053 | Unexplained hypotension: the spectrum of dynamic left ventricular outflow tract obstruction in critical care settings. | To illustrate the clinical and hemodynamic abnormalities caused by dynamic left ventricular outflow tract obstruction (LVOTO) in critical care setting.</AbstractText>We reviewed cases referred to Cardiology with echocardiographic evidence of LVOTO and their clinical presentations. We present those cases where LVOTO can transiently occur without hypertrophic cardiomyopathy when inotropic agents are used for hypotension.</AbstractText>Five women in the 50-70 age range and prior history of hypertension presented with various symptoms like chest discomfort, fatigue, dizziness, atrial fibrillation, and hypotension. An ejection systolic murmur was noted most often in the left third intercostal space and ECG revealed ST-T wave abnormalities. LVOTO caused by mitral systolic anterior motion was detected by echocardiography and catheterization excluded acute coronary disease. In critical care setting, LVOTO can occur due to apical ballooning syndrome, coronary disease, medications, volume depletion, and valvular abnormalities. Because this condition mimics acute coronary syndrome or other etiologies of hypotension in medical and surgical intensive care units, appropriate treatment can be delayed. Nonhypertrophic cardiomyopathy LVOTO usually responds well to fluid replacement, beta blockers, and medication changes.</AbstractText>LVOTO should be suspected especially in women presenting with hypotension and systolic murmur in critical care settings. Clinical acumen and timely echocardiography are required to effectively counter this transient but potentially lethal problem.</AbstractText> |
7,054 | Role of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and aldosterone antagonists in the prevention of atrial and ventricular arrhythmias. | Atrial arrhythmias, ventricular arrhythmias, and sudden cardiac death (SCD) are significant health problems and an economic burden to society. The renin-angiotensin-aldosterone system (RAAS) may play a key role in the occurrence of structural and electrical remodeling, potentially explaining the development of atrial and ventricular arrhythmias. Angiotensin II has been shown to regulate cardiac cell proliferation and to modulate cardiac myocyte ion channels. Results of post hoc analyses from prospective clinical trials appear to show that angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are most effective in the prevention of new-onset atrial fibrillation in patients with heart failure. It is difficult to determine if these agents are useful in the prevention of new-onset atrial fibrillation after myocardial infarction, and available evidence suggests that the benefit of ACE inhibitors and ARBs for prevention of new-onset atrial fibrillation in patients with hypertension appears limited to those with left ventricular hypertrophy. Patients with structural changes in cardiac muscle, such as those with heart failure and left ventricular hypertrophy, appear to benefit the most from RAAS blockade, possibly due to the theory of reversal of cardiac remodeling. There is no evidence, to our knowledge, that either ACE inhibitors or ARBs facilitate direct electrical current cardioversion in patients with atrial fibrillation; however, it appears that RAAS blockade may be useful in the prevention of recurrent atrial fibrillation after direct electrical current cardioversion. Whether ACE inhibitors may prevent life-threatening ventricular arrhythmias or SCD is unclear. Aldosterone antagonists appear to be useful for the prevention of SCD in patients with left ventricular systolic dysfunction. Results from ongoing clinical trials are anticipated to provide further insight on the potential roles of RAAS inhibitors for the prevention of cardiac arrhythmias. |
7,055 | [Genetic predisposition to systemic complications of arterial hypertension in maintenance haemodialysis patients]. | Cardiovascular disease is the most common cause of a high morbidity and mortality in patients on renal replacement therapy and is responsible for about 50% of deaths. Hypertension is the main risk factor for cardiovascular events in the general population as well as in haemodialysed (HD) patients. The hypertension in HD patients is caused by excess extracellular fluid volume (ECV) on the other hand hypertension resistant to normalization of ECV may result from the accelerated activity of the systemic and local--vascular renin-angiotensin-aldosteron system (RAAS). RAAS genes are potential etiological candidates for cardiovascular damage. The aim of the study was to evaluate the prevalence of hypertension, left ventricular hypertrophy, hypertensive retinopathy in patients treated with haemodialysis and to evaluate the association between the polymorphism of RAAS genes: ACE I/D, AGT M235T AT1R A1166C, CYP112 (-344) and the systemic complications of arterial hypertension such as hypertensive retinopathy, left ventricular hypertrophy and also mortality in haemodialysis patients.</AbstractText>The studied population consisted of 302 HD patients (175 men, 127 women) age 21-87, mean 56, at four dialysis units. Patients with cardiac defect, advanced coronary artery disease and atrial fibrillation were excluded from the study. 62 patients died during 3,5 years of observation. Methods consisted of tree times repeated blood pressure measurements before and post dialysis, echocardiography, direct opthalmoscopy (Keith-Wegener-Barker classification of hypertensive retinopathy) and DNA analysis--genotypes ACE I/D, AGT M235T AT1R A1166C, CYP11B2 T(-344)C were determined through PCR or PCR-RFLP method.</AbstractText>Hypertension was present in 72%, LVH in 84% haemodialysed patients. Arterial pressure correlated with LVMI values and hypertension was connected with LVH. Insufficient control of blood pressure and LVH were connected with worse survival in HD patients.</AbstractText>It seems that I/D polymorphism ACE gene and AC AT1 gene influence the development of hypertension and LVH in HD patients. The most dangerous in the development of hypertension and LVH was DD genotype ACE gene and CC AT1 gene. ACE I/D, AGT M/T, AT1 A/C, CYP11B2 T/C polymorphism appears to have no relation to the short-term prognosis in HD patients. The mortality did not differ among groups with different genotypes of ACE I/D, AGT M/T AT1 A/C, CYP11B2 T/C polymorphisms. Direct ophtalmoscopy seems to be an insufficient method in the estimation of the systemic complications of hypertension in haemodialysed patients.</AbstractText> |
7,056 | Chronic heart failure in the elderly: a current medical problem. | As a result of population ageing and improved medical care that contribute to better life expectancy, heart failure occurs more and more commonly in the elderly. In the USA approximately 80% of patients discharged from hospital with newly diagnosed heart failure are over 65 years of age, whereas 50% are over 75. The average 5-year mortality rate is about 50% in subjects with systolic dysfunction and similar in those with preserved left ventricular systolic function. Disorders of the cardiovascular system occurring in the elderly (e.g. increased left ventricular mass, myocardial rigidity, atrial fibrillation, decreased maximum oxygen uptake in cardiopulmonary exercise tests) result from the physiological ageing; they may also be caused by a concomitant cardiac failure syndrome. In the elderly, heart failure is often accompanied by concomitant conditions that often make diagnosis and treatment of chronic heart disease difficult. Non-specific clinical symptoms in the elderly as well as those associated with age (e.g. easy fatigability, exertional dyspnea) make a correct diagnosis difficult. The recognized biochemical marker of heart failure--brain natriuretic peptide, N-terminal pro-brain natriuretic peptide--has a limited diagnostic value in the elderly. Echocardiography plays a key role in the diagnosis. Owing to altered metabolism, impairment of hepatic processes to various degrees and decreased renal excretion of drugs, treatment requires attention, individual choice of drugs and doses, as well as periodic modification of both the doses and the intervals between them. Correct treatment improves quality of life and prolongs it. The aim of the present work is to present the differences in the pathophysiology, diagnostic evaluation and management of chronic heart failure in the elderly, in light of the current views and standards. |
7,057 | Atrial fibrillation in patients with implantable defibrillators. | Atrial fibrillation (AF) is common in patients who have implantable defibrillators and presents some unique challenges and opportunities. AF burden can be assessed more accurately, allowing for evaluation of therapy efficacy (drugs or ablation). It remains to be shown whether home monitoring of defibrillators to detect and treat AF more quickly can reduce cardiovascular and stroke end points. One major goal will be to reduce inappropriate shocks from atrial fibrillation. Otherwise, the goals of therapy remain the same-reduction of symptoms (including heart failure exacerbation and inappropriate implantable cardioverter defibrillator therapies) by controlling rate or rhythm and anticoagulation for stroke prophylaxis. |
7,058 | Drug therapy for atrial fibrillation. | Atrial fibrillation is the most frequently diagnosed arrhythmia. Prevalence increases with age, and the overall incidence is expected to increase as the population continues to age. Choice of pharmacologic therapy for atrial fibrillation depends on whether or not the goal of treatment is maintaining sinus rhythm or tolerating atrial fibrillation with adequate control of ventricular rates. Many new antiarrhythmic drugs are currently being tested in clinical trials. Drugs that target remodeling and inflammation have shown potential in prevention of atrial fibrillation, or as adjunctive therapy. |
7,059 | The impact of therapeutic hypothermia on neurological function and quality of life after cardiac arrest. | To assess the impact of therapeutic hypothermia on cognitive function and quality of life in comatose survivors of out of Hospital Cardiac arrest (OHCA).</AbstractText>We prospectively studied comatose survivors of OHCA consecutively admitted in a 4-year period. Therapeutic hypothermia was implemented in the last 2-year period, intervention period (n=79), and this group was compared to patients admitted the 2 previous years, control period (n=77). We assessed Cerebral Performance Category (CPC), survival, Mini Mental State Examination (MMSE) and self-rated quality of life (SF-36) 6 months after OHCA in the subgroup with VF/VT as initial rhythm.</AbstractText>CPC in patients alive at hospital discharge was significantly better in the intervention period with a CPC of 1-2 in 97% vs. 71% in the control period, p=0.003, corresponding to an adjusted odds ratio of a favourable cerebral outcome of 17, p=0.01. No significant differences were found in long-term survival (57% vs. 56% alive at 30 months), MMSE, or SF-36. Therapeutic hypothermia (hazard ratio: 0.15, p=0.007) and bystander CPR (hazard ratio 0.19, p=0.002) were significantly related to survival in the intervention period.</AbstractText>CPC at discharge from hospital was significantly improved following implementation of therapeutic hypothermia in comatose patients resuscitated from OCHA with VF/VT. However, significant improvement in survival, cognitive status or quality of life could not be detected at long-term follow-up.</AbstractText> |
7,060 | [The influence of anisodamine on cardiopulmonary resuscitation in rat]. | To evaluate the influence of anisodamine (Ani) on restoration of spontaneous circulation (ROSC) and cardiopulmonary resuscitation (CPR) rate in a randomized, blinded experimental study so as to explore a new treatment for CPR.</AbstractText>Forty-five Sprague-Dawley (SD) rats were randomized to three groups: control group (0.9% normal saline), epinephrine (Epi) group and Epi plus Ani group (combined group), 15 rats in each group. Ventricular fibrillation (VF) or asystole was induced by transoesophageal alternating current stimulation. A blinded drug administration and mechanical chest compression were used in this study (Epi 200 microg/kg, Ani 10 mg/kg). ROSC rate and resuscitation rate were compared among these groups.</AbstractText>Combined group had higher ROSC rate(93.3% vs. 46.7%), resuscitation rate (80.0% vs.33.3%) and survival rate within 3 hours (83.3% vs.20.0%) compared with Epi group (all P<0.05). ROSC occurred only in one rat of control group. Mean arterial pressure (MAP) at the beginning of ROSC in Epi group was higher compared with combined group (P<0.05). After ROSC, MAP decreased in both drug groups, especially after 5 minutes of ROSC, and MAP in Epi group was lower than that of combined group. There was difference between the two groups till 30 minutes after ROSC (all P<0.05) .</AbstractText>Administration of Epi plus Ani at the beginning of treatment for cardiac arrest could improve ROSC rate and resuscitation rate.</AbstractText> |
7,061 | [A report of 463 in-hospital cardiopulmonary resuscitation based on the "Utstein Style"]. | Assessment of outcomes and outcome-related factors of in-hospital cardiopulmonary resuscitation (CPR) based on the "Utstein Style".</AbstractText>The study was designed as a prospective, single-institution, registry investigation of 463 patients (included adult and pediatric patients) for whom a CPR was attempted.</AbstractText>The study population consisted of 320 (69.1%) male patients and 143 (30.9%) female patients. The age range of 45-54, 55-64, 65-74 were ranked the first, the second and third highest. In the past medical history, cardiovascular disease and cerebrovascular disorder were two main disorders, accounting for 36.3% (168/463) and 9.9% (46/463), respectively. Ventricular fibrillation (VF) was the initial electrocardiographic (ECG) change in 74 patients (16.0%). Two hundred and seventy-three patients received the in-hospital CPR, and 190 patients received the pre-hospital CPR. Spontaneous circulation returned in 34.6% (160/273) of the in-hospital patients after CPR, and 16.6% (77/273) survived for 24 hours and 10.4% (48/273) survived up to the time of discharge. The rates of restoration of spontaneous circulation (ROSC) and survival of the in-hospital CPR were higher than those of the pre-hospital CPR [47.6% (130/273) vs. 15.8% (30/190), 13.9% (38/273) vs. 5.3% (10/190), both P<0.01].</AbstractText>Prospective "Utstein Style" data collection for CPR is proved to be a valuable tool for the evaluation of management and outcome following in-hospital cardiopulmonary arrest, but the rate of survival for in-hospital resuscitation still seems to be too low. The further improvement of CPR outcome is necessary.</AbstractText> |
7,062 | Sleep-disordered breathing: autonomic mechanisms and arrhythmias. | Obstructive sleep apnea (OSA) is present in at least 2% to 4% of the general population. Central sleep apnea (CSA), though less common, is highly prevalent in patients with heart failure. Both forms of sleep apnea exert strong modulatory effects on the autonomic nervous system at night through a number of mechanisms including central respiratory-cardiac coupling in the brainstem, chemoreflex stimulation, baroreflexes, and reflexes relating to lung inflation. Arousals also contribute to the autonomic disturbance. Although sleep is normally a time when parasympathetic modulation of the heart predominates and myocardial electrical stability is enhanced, OSA and CSA disturb this quiescence, creating an autonomic profile in which both profound vagal activity leading to bradyarrhythmias, and sympatho-excitation favoring ventricular ectopy are observed. The resulting tendency toward cardiac arrhythmia may directly contribute to sudden cardiac death and premature mortality in patients with sleep apnea. Therapy consists largely of treatment with continuous positive airway pressure, which has been shown to improve autonomic profile and reduce nocturnal arrhythmias. |
7,063 | Spectral analysis of intracardiac electrograms during induced and spontaneous ventricular fibrillation in humans. | Very limited data are available on the differences between spontaneous and induced episodes of ventricular fibrillation (VF) in humans. The aim of the study was to compare the spectral characteristics of the electrical signal recorded by an implantable cardioverter defibrillator (ICD) during both types of episodes.</AbstractText>Thirteen ICD patients with at least one spontaneous and one induced VF recorded by the device were included in the study. A spectral representation was obtained for the first 3 s of the intracardiac unipolar electrogram during VF. The dominant frequency (f(d)), the peak power at f(d), an organization index (OI), a bandwidth measurement, and an estimate of the correlation with a sinusoidal wave (leakage) were estimated for each episode. The f(d) was higher in induced episodes (4.75 +/- 0.57 vs. 3.95 +/- 0.59 Hz for the spontaneous episodes, P = 0.002), as well as the degree of organization assessed by the OI, bandwidth, and leakage parameters.</AbstractText>Clinical and induced VF episodes in humans have different spectral characteristics. Changes in the electrophysiological substrate or in the location of the arrhythmia wavefront at onset could play a role to explain the observed differences.</AbstractText> |
7,064 | Defibrillator shock due to ventricular trigeminy. | A 56-year-old lady with arrhythmogenic right ventricular cardiomyopathy had a shock for ventricular trigeminy. The device diagnosed this as ventricular fibrillation because of its binning algorithm, which does not use a consecutive, or a proportional counter. A beat is binned as a fibrillation beat only if the current cycle length is in the fibrillation zone and the running average of the previous four cycle lengths are in the fibrillation or ventricular tachycardia zone. Reprogramming the device into a single detection zone will help prevent shocks in this situation. |
7,065 | Atrial fibrillation in acute myocardial infarction: a systematic review of the incidence, clinical features and prognostic implications. | Atrial fibrillation (AF), the most commonly encountered clinical arrhythmia, often complicates acute myocardial infarction (AMI) with an incidence between 6 and 21%. Predictors of the arrhythmia in the setting of AMI include advanced age, heart failure symptoms, and depressed left ventricular function. The bulk of evidence demonstrates that AF in patients hospitalized for AMI has serious adverse prognostic implications regarding in-hospital, but also long-term mortality. This seems to apply for all patient populations studied without significant differences related to the treatment of AMI (i.e. no reperfusion therapy vs. thrombolysis vs. percutaneous coronary intervention). Mortality is particularly high in patients who have congestive heart failure and/or a reduced left ventricular ejection fraction. Finally, there are persuasive data indicating that AF complicating AMI not only increases the risk for ischaemic stroke during hospitalization but also during follow-up. This seems to apply also for transient AF which has reversed back to sinus rhythm at the time of discharge. These observations emphasize the need for prospective studies evaluating optimal therapeutic approaches for patients with AMI complicated by AF. |
7,066 | [Radiofrequency ablation of long standing persistent atrial fibrillation and post-incisional macroreentrant right atrial tachycardia in patient with advanced biventricular heart failure--case raport]. | We present a case of a 54 year old male with a long-standing atrial fibrillation (AF) who was scheduled for cardiac transplantation due to the progression of heart failure. Previous treatment included pacemaker implantation, mitral valvuloplasty, a-v node modification using RF ablation, and pharmacological therapy. This time the patient underwent complex AF ablation which consisted of pulmonary vein isolation, mitral and left atrial roof line creation, cavo-tricuspid isthmus ablation and ablation of complex fractionated atrial electrograms, which resulted in restoration of sinus rhythm. Because of the right atrial post-incisional tachycardia the patient underwent second ablation session. This complex invasive approach occurred successful. The patient remains in sinus rhythm with improved left ventricular function and better NYHA class over a 12-month follow-up. |
7,067 | [Proarrhythmic effect of propafenone in patients with atrial fibrillation and atrial flutter]. | We present two cases of proarrhythmia after propafenone treatment. In the first case slowing of the flutter cycle length from 205 ms to 290 ms resulted in a change from well tolerated two to one atrioventricular conduction to one to one conduction with hypotension and presyncope. In the second case organization of atrial fibrillation to atypical atrial flutter and use-dependent left bundle branch block resulted in fast broad QRS tachycardia that mimicked ventricular tachycardia. |
7,068 | Differential effects of propofol and sevoflurane on ischemia-induced ventricular arrhythmias and phosphorylated connexin 43 protein in rats. | The effects of anesthetics on ischemia-induced ventricular arrhythmias remain poorly studied. This study investigated the effects of propofol and sevoflurane on the survival rate and morbidity as a result of ventricular arrhythmias, and defined a possible mechanism for the arrhythmogenic properties of anesthetics during acute myocardial ischemia.</AbstractText>Under anesthesia with intraperitoneal sodium pentobarbital, Sprague-Dawley rats underwent 30 min of left anterior descending coronary artery ligation. The rats were divided into a low-dose propofol (Prop-LD) group (39 mg X kg(-1) X hr(-1), n = 18), a high-dose propofol group (78 mg x kg(-1) x hr(-1), n = 18), a sevoflurane group (2.5%, n = 18) and a control group (n = 18). The survival rate and morbidity as a result of ventricular arrhythmias were determined, and the amount of phosphorylated connexin 43 protein was measured 30 min after coronary artery ligation.</AbstractText>The survival rate was 83% (15 of 18), 94% (17 of 18), 89% (16 of 18), and 67% (12 of 18, P = 0.038 vs. Prop-LD) in the control, Prop-LD, high-dose propofol, and sevoflurane groups, respectively. Sustained ventricular tachycardia was observed in 83% (15 of 18), 39% (7 of 18, P = 0.011 vs. control), 50% (9 of 18, P = 0.039 vs. control) and 94% (17 of 18, P < 0.01 vs. Prop-LD) in the control, Prop-LD, high-dose propofol, and sevoflurane groups, respectively. Immunoblotting showed a marked reduction in the amount of phosphorylated connexin 43 in the control and sevoflurane groups, as compared with the Prop-LD and high-dose propofol groups (P < 0.05).</AbstractText>The authors' results suggest that propofol preserves connexin 43 phosphorylation during acute myocardial ischemia, as compared with sevoflurane, and this might protect the heart from serious ventricular arrhythmias during acute coronary occlusion.</AbstractText> |
7,069 | Safety of pulsed electric devices. | The strength-duration curve for tissue excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. We tested several short-duration electric generators: five electric fence energizers, the Taser X26 and a high-frequency generator to determine their current-versus-time waveforms. We estimated their safety characteristics using existing IEC and UL standards for electric fence energizers. The current standards are difficult to follow, with cumbersome calculations, and do not explicitly explain the physiological relevance of the calculated parameters. Hence we propose a new standard. The proposed new standard would consist of a physical RC circuit with a certain time constant. The investigator would discharge the device into a passive resistor-capacitor circuit and measure the resulting maximum voltage. If the maximum voltage does not exceed a limit, the device passes the test. |
7,070 | Epicardial border zone overexpression of skeletal muscle sodium channel SkM1 normalizes activation, preserves conduction, and suppresses ventricular arrhythmia: an in silico, in vivo, in vitro study. | In depolarized myocardial infarct epicardial border zones, the cardiac sodium channel (SCN5A) is largely inactivated, contributing to low action potential upstroke velocity (V(max)), slow conduction, and reentry. We hypothesized that a fast inward current such as the skeletal muscle sodium channel (SkM1) operating more effectively at depolarized membrane potentials might restore fast conduction in epicardial border zones and be antiarrhythmic.</AbstractText>Computer simulations were done with a modified Hund-Rudy model. Canine myocardial infarcts were created by coronary ligation. Adenovirus expressing SkM1 and green fluorescent protein or green fluorescent protein alone (sham) was injected into epicardial border zones. After 5 to 7 days, dogs were studied with epicardial mapping, programmed premature stimulation in vivo, and cellular electrophysiology in vitro. Infarct size was determined, and tissues were immunostained for SkM1 and green fluorescent protein. In the computational model, modest SkM1 expression preserved fast conduction at potentials as positive as -60 mV; overexpression of SCN5A did not. In vivo epicardial border zone electrograms were broad and fragmented in shams (31.5 +/- 2.3 ms) and narrower in SkM1 (22.6 +/- 2.8 ms; P=0.03). Premature stimulation induced ventricular tachyarrhythmia/fibrillation >60 seconds in 6 of 8 shams versus 2 of 12 SkM1 (P=0.02). Microelectrode studies of epicardial border zones from SkM1 showed membrane potentials equal to that of shams and V(max) greater than that of shams as membrane potential depolarized (P<0.01). Infarct sizes were similar (sham, 30 +/- 2.8%; SkM1, 30 +/- 2.6%; P=0.86). SkM1 expression in injected epicardium was confirmed immunohistochemically.</AbstractText>SkM1 increases V(max) of depolarized myocardium and reduces the incidence of inducible sustained ventricular tachyarrhythmia/fibrillation in canine infarcts. Gene therapy to normalize activation by increasing V(max) at depolarized potentials may be a promising antiarrhythmic strategy.</AbstractText> |
7,071 | Potential role of home monitoring to reduce inappropriate shocks in implantable cardioverter-defibrillator patients due to lead failure. | Lead dysfunctions in implantable cardioverter-defibrillator (ICD) patients can lead to inappropriate shocks or even complete loss of function of the device. Home monitoring (HM) systems are capable of daily data transmissions regarding the device and the lead integrity as well as information concerning anti-arrhythmic therapies. We therefore analysed the data from the Biotronik HM system whether it enables physicians to react quickly on serious ICD malfunctions and to avoid inappropriate shocks.</AbstractText>Fifty-four patients who had to undergo resurgery due to malfunctions of the ICD lead were included. Eleven of them were on HM interrogating the device every night at 3 am. If any adverse event was detected, a fax alert was sent to the clinic and the patients were asked for in-hospital ICD interrogation. The rate of inappropriate shocks and symptomatic pacemaker inhibition due to oversensing was compared with the 43 patients without remote surveillance. HM sent alert messages in 91% of all incidents. All lead failures became obvious because of oversensing of high frequency artefacts. Only in 18%, changes in the pacing impedance were noticed, in all cases preceded by oversensing. Eighty per cent of the patients were asymptomatic at the first onset of oversensing. Only one patient suffered an inappropriate shock as first manifestation of lead failure. Compared with the patients without HM, inappropriate shocks occurred in 27.3% in the HM group vs. 46.5% (P = n.s.). This trend gains statistical significance, if the compound endpoint of symptomatic lead failure consisting of inappropriate shocks and symptomatic pacemaker inhibition due to oversensing is focused: 27.3% event in the HM group vs. 53.4% in the group without HM (P = 0.04). Event messages were despatched in a mean of 54 days after the last ICD interrogation and 56 days before next scheduled visit. Thus, 56 days of reaction time are gained to avoid adverse events.</AbstractText>In 91% of all lead-related ICD complications, the diagnosis could be established correctly by an alert of the HM system. Mostly, the first incident sent was oversensing of artefacts, falsely detected as ventricular fibrillation-the VF zone. The automatic HM surveillance system enables physicians to detect severe lead problems early and to react quickly; thus, it might have a potential to avoid inappropriate shocks due to lead failure and T-wave oversensing.</AbstractText> |
7,072 | Atrial fibrillation and congestive heart failure. | The present review will examine the prognostic importance of atrial fibrillation and heart failure, explore the different therapeutic options for treating atrial fibrillation and present the results of the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial.</AbstractText>The Atrial Fibrillation and Congestive Heart Failure trial was a randomized trial involving patients with both atrial fibrillation and heart failure. The trial was designed to compare the maintenance of sinus rhythm with the control of ventricular rate in patients with left ventricular dysfunction, heart failure and a history of atrial fibrillation. There was no significant difference in the rate of death from cardiovascular causes in the rhythm-control group as compared with the rate-control strategy. In addition, there was no significant difference in any of the secondary outcomes including death from any cause, worsening heart failure or stroke. The rate-control strategy eliminated the need for repeated cardioversion and reduced rates of hospitalization.</AbstractText>The results of the Atrial Fibrillation and Congestive Heart Failure trial indicate that a routine strategy of rhythm control does not reduce rate of death and suggest that rate control should be considered a primary approach for patients with atrial fibrillation and heart failure.</AbstractText> |
7,073 | Mesenchymal stem cells improve outcomes of cardiopulmonary resuscitation in myocardial infarcted rats. | We hypothesized that administration of allogeneic bone marrow mesenchymal stem cells (MSCs) by intravenous, intraventricular or intramyocardial injection could improve myocardial function after survival time after cardiopulmonary resuscitation in myocardial infarcted rats. Myocardial infarction was induced by ligation of the left anterior descending artery in 54 rats (6 groups, 9 rats for each group). Left ventricular remodeling was quantitated weekly by ejection fraction (EF) measurement. One month after ligation, animals were randomized to receive injection of either MSCs 5x10(6) labeled with PKH26 in phosphate buffer solution (PBS) or PBS alone as a placebo. MSCs or PBS were administered by injection into the right femoral vein, the left ventricular cavity, or into the infracted anterior ventricular free wall. Four weeks after MSC or PBS injection, ventricular fibrillation (VF) was induced and untreated for 6 min, followed by 6 min of CPR prior to defibrillation. Hemodynamics, including cardiac index (CI), left ventricular dP/dt40 (dP/dt40), left ventricular negative dP/dt (-dP/dt) and left ventricular diastolic pressure (LVDP) were measured at baseline and hourly following return of spontaneous circulation (ROSC). Labeled MSCs were observed in 5 microm sections obtained with a cryostat from each harvested heart. Independently of the site of injection of MSCs, EF, CI, dP/dt40, -dP/dt, and LVDP were significantly improved and sustained before and after CPR in the animals treated with MSCs and were associated with significantly increased survival time when compared with the corresponding PBS treated animals. |
7,074 | Long-term outcome after a first episode of heart failure. A prospective 7-year study. | Heart failure (HF) is a major issue of public health in contemporary aging populations. The objectives of the present study were to assess the long-term survival of a contemporary cohort of patients discharged after a first hospitalization for HF and identify variables associated with adverse outcome.</AbstractText>We prospectively included consecutive patients (n=735) discharged from 11 healthcare establishments of the Somme department (France) after a first hospitalization for HF during 2000. The 7-year observed survival was compared with the expected survival of the general population.</AbstractText>Mean age of the study group was 75+/-12 years and 48% of patients were women. Left ventricular ejection fraction was measured in 628 patients (85%). During the 7-year follow-up, 483 patients (67%) died. The 5- and 7-year observed survival rates were dramatically lower than the expected survival of the matched general population (42% vs. 70%, and 33% vs. 59%, respectively). Relative survival (observed/expected survival) was 60% at 5 years and 55% at 7 years. Multivariable analysis identified cancer, stroke, diabetes, prior myocardial infarction, chronic obstructive pulmonary disease, chronic atrial fibrillation, age, and hyponatraemia as independent predictors of 7-year mortality.</AbstractText>In Europe, the long-term outcome of patients with new-onset HF is still extremely poor. Better implementation of guideline-oriented therapeutic strategies is needed to improve prognosis of this increasingly prevalent condition.</AbstractText>Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
7,075 | Distinct contractile and molecular differences between two goat models of atrial dysfunction: AV block-induced atrial dilatation and atrial fibrillation. | Atrial dilatation is an independent risk factor for thromboembolism in patients with and without atrial fibrillation (AF). In many patients, atrial dilatation goes along with depressed contractile function of the dilated atria. While some mechanisms causing atrial contractile dysfunction in fibrillating atria have been addressed previously, the cellular and molecular mechanisms of atrial contractile remodeling in dilated atria are unknown. This study characterized in vivo atrial contractile function in a goat model of atrial dilatation and compared it to a goat model of AF. Differences in the underlying mechanisms were elucidated by studying contractile function, electrophysiology and sarcoplasmic reticulum (SR) Ca2+ load in atrial muscle bundles and by analyzing expression and phosphorylation levels of key Ca2+-handling proteins, myofilaments and the expression and activity of their upstream regulators. In 7 chronically instrumented, awake goats atrial contractile dysfunction was monitored during 3 weeks of progressive atrial dilatation after AV-node ablation (AV block goats (AVB)). In open chest experiments atrial work index (AWI) and refractoriness were measured (10 goats with AVB, 5 goats with ten days of AF induced by repetitive atrial burst pacing (AF), 10 controls). Isometric force of contraction (FC), transmembrane action potentials (APs) and rapid cooling contractures (RCC, a measure of SR Ca2+ load) were studied in right atrial muscle bundles. Total and phosphorylated Ca2+-handling and myofilament protein levels were quantified by Western blot. In AVB goats, atrial size increased by 18% (from 26.6+/-4.4 to 31.6+/-5.5 mm, n=7 p<0.01) while atrial fractional shortening (AFS) decreased (from 18.4+/-1.7 to 12.8+/-4.0% at 400 ms, n=7, p<0.01). In open chest experiments, AWI was reduced in AVB and in AF goats compared to controls (at 400 ms: 8.4+/-0.9, n=7, and 3.2+/-1.8, n=5, vs 18.9+/-5.3 mmxmmHg, n=7, respectively, p<0.05 vs control). FC of isolated right atrial muscle bundles was reduced in AVB (n=8) and in AF (n=5) goats compared to controls (n=9) (at 2 Hz: 2.3+/-0.5 and 0.7+/-0.2 vs 5.5+/-1.0 mN/mm2, respectively, p<0.05). APs were shorter in AF, but unchanged in AVB goats. RCCs were reduced in AVB and AF versus control (AVB, 3.4+/-0.5 and AF, 4.1+/-1.4 vs 12.2+/-3.2 mN/mm2, p<0.05). Protein levels of protein kinase A (PKA) phosphorylated phospholamban (PLB) were reduced in AVB (n=8) and AF (n=8) vs control (n=7) by 37.9+/-12.4% and 29.7+/-10.1%, respectively (p<0.01), whereas calmodulin-dependent protein kinase II (CaMKII) phosphorylated ryanodine channels (RyR2) were increased by 166+/-55% in AVB (n=8) and by 146+/-56% in AF (n=8) goats (p<0.01). PKA-phosphorylated myosin-binding protein-C and troponin-I were reduced exclusively in AVB goat atria (by 75+/-10% and 55+/-15%, respectively, n=8, p<0.05). Atrial dilatation developing during slow ventricular rhythm after complete AV block as well as AF-induced remodeling are associated with atrial contractile dysfunction. Both AVB and AF goat atria show decreased SR Ca2+ load, likely caused by PLB dephosphorylation and RYR2 hyperphosphorylation. While shorter APs further compromise contractility in AF goat atria, reduced myofilament phosphorylation may impair contractility in AVB goat atria. Thus, atrial hypocontractility appears to have distinct molecular contributors in different types of atrial remodeling. |
7,076 | [Study of the stroke and coronary risks in hypertensive patients over 54 years of age in the primary care practice]. | Quantification of stroke risk is not always performed in hypertensive patients in Primary Care.</AbstractText>This was an epidemiological study in hypertensive patients aged 55 years and older attending primary care centres in Spain. The D'Agostino Stroke Risk Scale, using data from the Framingham Study, was used for assessment of stroke risk.</AbstractText>We analysed 4,945 patients (mean age, 66.8 years; 50.9% females). Mean blood pressure (BP) values were 145/86 mmHg in men and 143.7/84.7 mmHg in women (p < 0.001). The majority of patients (80.5%) showed high BP values that were above the values recommended in the guidelines, despite most of them (89.6%) receiving pharmacological antihypertensive treatment. 41% of patients were diabetics. The 10-year global risk of stroke was 22.5%, and was higher in men (28.6% vs. 16.8%; P < 0.001). The risk of stroke increased with age, being more marked in women. Several risk factors showed a statistically significant association with the risk of stroke. From higher to lower significance, these risk factors were: age, left ventricular hypertrophy (LVH), cardiovascular disease, systolic BP, auricular fibrillation, diabetes, cigarette smoking, control of BP, gender, and antihypertensive treatment. The 10-year coronary risk was higher in men (24.2% vs. 16.0%; p < 0.001) and was significantly related to the 10-year risk of stroke (r = 0.626).</AbstractText>The risk of stroke in the Spanish hypertensive population is high, and is significantly higher in men, although it shows a larger age-related increase in women. Linear regression analysis showed a moderate, but statistically significant, correlation between coronary risk and risk of stroke. Apart from all the variables included in the Framingham Stroke Risk Model, gender, control of BP, and antihypertensive treatment accounted significantly and independently as calculated risk factors for incidence of stroke.</AbstractText> |
7,077 | [Clinical features of unexpected sudden death clustered in 7 families in Yunnan Province]. | To investigate the clinical features of unexpected sudden death (SUD) clustered in families in Yunnan province.</AbstractText>This retrospective study analyzed the clinical features of SUD occurred between July to September 2005 in 7 families in Yunnan province.</AbstractText>All 16 SUD patients shared common clinical features such as fatigue and repeated syncope and one group of SUD patients (n = 8 from 4 families) presented with the gastric intestinal tract manifestations including nausea, vomiting, abdominal pain and diarrhea with suspected dietary history and abnormal laboratory enzyme findings (GOT/GPT, CK/CKMB, LDH/LDH1 etc.). In SUD patients without gastric intestinal tract manifestations (n = 8 from 3 families), there were no clear symptoms before death and repeated ventricular tachycardia and ventricular fibrillation were recorded in one survivor. There was no clear evidence for the involvements of hereditary and infectious factors for observed SUD.</AbstractText>The reason for the unexpected sudden death clustered in 7 families in Yunnan remains unclear. Repeated syncope and fatigue served as the common clinical features in the presence or absence of gastric intestinal tract manifestations in all SUD cases. Further studies are needed to clarify the pathology and detailed clinical manifestations of SUD occurred in this area.</AbstractText> |
7,078 | [Prognostic value of microvolt level T-wave alternans in patients at high risk of sudden cardiac death]. | To explore the predict value of microvolt level T-wave alternans (MTWA) for malignant ventricular arrhythmia (MVA) and sudden cardiac death (SCD) in high risk patients.</AbstractText>A total of 105 healthy subjects (control group) and 138 patients with history of VT or VF or patients with LVEF < or = 45% (SCD high risk group) were included in this study (mean age 52 years old). MTWA, LVEF, HRV, NSVT, QRS, QTc values and MACE data (death, causes of death, MVA, re-hospitalization, syncope) during follow up (12.0 +/- 1.3) months were obtained.</AbstractText>The normal reference value of MTWA was defined as < 37 microV. Positive rate in SCD high risk group was significantly higher than that in control group (45.7% vs. 4.8%, P < 0.01). There was no cardiovascular event report in control group. In SCD high risk group, there were 11 deaths (MTWA positive rate 81.8%) including 7 SCD (MTWA positive rate 85.7%), 17 MVA (MTWA positive rate 88.2%), 9 cases of syncope (MTWA positive rate 77.8%), 21 cases of re-hospitalization during the follow up (MTWA positive rate 85.7%). Logistic regression analysis revealed that positive MTWA, a history of myocardial infarction and LVDd > or = 60 mm were risk factors for all cause of death and positive MTWA was the only factor to predict SCD. The factors related to MVA in turn were positive MTWA, LVEF < or = 35%, a history of cardiopulmonary resuscitation and a history of syncope. Positive MTWA and LVEF < or = 35% are the independent risk factors for predicting MVA (P < 0.01). The sensitivity was 91% and specifity was 66% by combined use of positive MTWA and LVEF < or = 35% to predict MVA. MTWA positive rates were 68.3% and 87.5% respectively in 41 ICD patients and ICD patients with automatic shock during follow up.</AbstractText>Non-invasive MTWA measurement could be used as a screening tool to predict SCD or MVA in high risk patients.</AbstractText> |
7,079 | [Transient change of cardiac action potential and intracellular Ca2+ during ventricular fibrillation]. | The cardiac action potential (AP) and the intracellular Ca(2+) transient (CaT) are closely associated under normal physiological conditions, but not during ventricular fibrillation (VF). The purpose of this study was to determine whether this dissociation is directly related to the higher activation rate during VF.</AbstractText>We optically mapped AP and CaT simultaneously in nine isolated rabbit hearts. Pinacidil, a K(ATP) channel opener, was used to shorten the action potential duration (APD) in order to capture tissue at fast pacing rates or to induce ventricular tachycardia (VT) comparable to VF activation rates. Mutual information (MI) was used to calculate the degree of AP and CaT coupling.</AbstractText>Pinacidil (40 micromol/L) infusion significantly shortened APD. The averaged cycle length (CL) of VF without Pinacidil was (77 +/- 13) ms, whereas the shortest CL achieved during VT under Pinacidil infusion was 76 ms. MIs during fast pacing (1.13 +/- 0.15) bits and fast VT (0.88 +/- 0.18) bits were higher than those during baseline VF (0.39 +/- 0.11) bits, VF with Pinacidil infusion (0.21 +/- 0.07) bits and VF after Pinacidil washout (0.36 +/- 0.15) bits. MIs during fast pacing or fast VT were higher than those of VFs at comparable dominant frequencies.</AbstractText>CaT is closely associated with the AP during fast pacing and fast VT, but not during VF. The reduced MI during VF is not secondary to the fast rate of ventricular activation.</AbstractText> |
7,080 | [Transmural heterogeneity of calcium handling proteins in the mechanism of porcine model of ventricular fibrillation]. | To investigate the role of heterogeneous expression of calcium handling proteins and spatial heterogeneity of APD restitution in the maintenance mechanism of ventricular fibrillation.</AbstractText>During programmed electrical simulation, APD restitution curves in the endocardium and epicardium of LV were constructed by plotting APD100 and diastolic interval. APD alternans, delayed after depolarization events were recorded simultaneously. Endocardial and epicardial myocytes were isolated from LV base and apex. Real time-PCR and Western blotting were performed to determine the relative messenger RNA and protein expression levels of calcium handling proteins.</AbstractText>The normal hearts have spatial heterogeneity of action potential restitution property and transmural heterogeneity of calcium handling proteins. The slopes of the APD restitution curve in the endocardium were significantly steeper than those in epicardium, and the slopes of APD curve at the LV apex were significantly steeper than those in LV base. However, delayed after depolarization events with larger amplitude and earlier onset consistently occurred in the endocardium of LV base. After programmed electrical simulation, the expression of messenger RNA of RyR2, SERCA2a except for Calstabin2 significantly decreased (by 57% and 41%, respectively, P < 0.05) in the endocardium of the base, while the expression of RyR2, SERCA2a, Calstabin2 significantly increased (by 90%, 78%and 64%, respectively, P < 0.05) in the epicardium of LV base. Although transmural heterogeneity of calcium handling proteins at the LV apex were also observed after rapid pacing, there is no significant differences in the transmural heterogeneity at the LV apex compared to the LV base. The base of LV has unique calcium handling properties.</AbstractText>It has been shown that Calcium cycling could modulate APD restitution property in the intact heart. The interaction between action potential and calcium dynamics instabilities is one of the most important reasons why simple criterion such as the APD restitution slope > 1 may fail to accurately predict the onset of APD alternans.</AbstractText> |
7,081 | [The prospective study on the prognosis in patients with ventricular tachycardia or fibrillation treated with implantable automatic cardioverter defibrillator]. | To explore the effect of implantable automatic cardioverter defibrillator (ICD) on improvement of the prognosis of patients with ventricular tachycardia or fibrillation (VT/VF). To compare the advantages and disadvantages of ICD with antiarrhythmic drug, to select the best indication of ICD and review the protocol of the following-up of ICD patients, and present scientific evidence for the morebroad popularization who needs ICD in China.</AbstractText>In 99 selected patients who had the indication of class I, 27 patients were treated by ICD (ICD group), and 72 patients were not (non-ICD group). Patients in the two groups had the similar basic clinical characteristics. The incidence of syncope, CPR, and VF in ICD group were more common than those in non-ICD group. Patients in the two groups received same basic therapy. The total mortality rate and the incidence of cardiac events in two groups were compared in 3 months, 6 months, 12 months and 15 months.</AbstractText>The total mortality rate and the incidence of cardiac events in ICD group were significantly lower than those in non-ICD group in the follow-up period. The mortality rate in ICD group is 0, and the mortality rate in non-ICD group is 20.8%.</AbstractText>(1) ICD treatment can decrease the incidence of cardiac events of patients with high risk of sudden cardiac death (SCD), and improve their survival. (2) The key measures to insure the efficacy, safety, and cost-effectiveness of ICD treatment is: to select the patients correctly, to optimize the implanting process and the follow-up, and use rational assistant therapy.</AbstractText> |
7,082 | DDESC: Dragon database for exploration of sodium channels in human. | Sodium channels are heteromultimeric, integral membrane proteins that belong to a superfamily of ion channels. The mutations in genes encoding for sodium channel proteins have been linked with several inherited genetic disorders such as febrile epilepsy, Brugada syndrome, ventricular fibrillation, long QT syndrome, or channelopathy associated insensitivity to pain. In spite of these significant effects that sodium channel proteins/genes could have on human health, there is no publicly available resource focused on sodium channels that would support exploration of the sodium channel related information.</AbstractText>We report here Dragon Database for Exploration of Sodium Channels in Human (DDESC), which provides comprehensive information related to sodium channels regarding different entities, such as "genes and proteins", "metabolites and enzymes", "toxins", "chemicals with pharmacological effects", "disease concepts", "human anatomy", "pathways and pathway reactions" and their potential links. DDESC is compiled based on text- and data-mining. It allows users to explore potential associations between different entities related to sodium channels in human, as well as to automatically generate novel hypotheses.</AbstractText>DDESC is first publicly available resource where the information related to sodium channels in human can be explored at different levels. This database is freely accessible for academic and non-profit users via the worldwide web http://apps.sanbi.ac.za/ddesc.</AbstractText> |
7,083 | Nitroglycerin and epinephrine improve coronary perfusion pressure in a porcine model of ventricular fibrillation arrest: a pilot study. | Cardiac arrest remains one of the leading causes of death worldwide. European Resuscitation Council Guidelines for Resuscitation 2005 recommend epinephrine for its treatment.</AbstractText>To estimate whether the administration of a vasodilatator such as nitroglycerin in combination with epinephrine during cardiopulmonary resuscitation would improve resuscitation outcome in an established model of ventricular fibrillation.</AbstractText>Prospective, randomized, blinded, controlled study.</AbstractText>Animal research laboratory. Ventricular fibrillation was induced in 20 Landrace/Large-White pigs. It remained untreated for 8 min before attempting resuscitation precordial compressions, mechanical ventilation, and electrical defibrillation. Animals were randomized into two groups, 10 animals each. Group A received saline as placebo (10 mL dilution, bolus) and epinephrine (0.02 mg/kg). Group B received nitroglycerin (50 microg/kg) and epinephrine (0.02 mg/kg) during cardiopulmonary resuscitation. Electrical defibrillation was attempted after 10 min of ventricular fibrillation.</AbstractText>Four animals in group A restored spontaneous circulation in comparison to eight in Group B. Coronary perfusion pressure (p < 0.0001) was significantly increased in Group B during cardiopulmonary resuscitation.</AbstractText>A vasodilatator, when administered in combination with a vasopressor such as epinephrine during cardiopulmonary resuscitation, increases coronary perfusion pressure.</AbstractText> |
7,084 | Demonstration of a very rare coronary anomaly with multislice computed tomography: arising of right coronary artery from left anterior descending artery. | Arising of right coronary artery from left anterior descending artery is a very rare anomaly. We present a case with this anomaly that was also demonstrated with multislice computed tomography. |
7,085 | Spatial and temporal organization of the dominant frequencies in the fibrillating heart: body surface potential mapping in a rare case of sustained human ventricular fibrillation. | The aim of this study was to assess the spatial and temporal variability of dominant fibrillation frequencies in a rare case of sustained human ventricular fibrillation (VF).</AbstractText>Body surface potential mapping was performed in a patient with sustained VF and who was supported by a biventricular assist device. Dominant frequencies at 54 body sites were calculated from two recordings obtained 38 days apart. Variability of dominant frequencies between recordings and across body sites was quantified. Median dominant frequencies within recordings varied between 6.1 and 7.2 Hz in recording 1 and 5.6 and 6.6 Hz in recording 2, indicating a significant reduction in dominant frequencies between the recordings (P < 0.0001). Dominant frequencies differed across body sites by a mean (range) of 1.7 (0.4-2.8) Hz.</AbstractText>In this rare case of sustained VF, there was significant spatial and temporal variability of VF dominant frequencies. These findings should be considered in future ECG studies on VF where the spatial variability of dominant frequency might not otherwise have been considered.</AbstractText> |
7,086 | Induction of ventricular fibrillation rather than ventricular tachycardia predicts tachyarrhythmia recurrences in patients with idiopathic dilated cardiomyopathy and implantable cardioverter defibrillator for secondary prophylaxis. | We sought to investigate the association of inducibility of polymorphic ventricular tachycardia or ventricular fibrillation (PVT/VF) or sustained monomorphic ventricular tachycardia (SMVT) at standardized programmed ventricular stimulation (PVS) with the long-term likelihood of sudden death and/or fast VT in a large cohort of patients with idiopathic non-ischaemic dilated cardiomyopathy (DCM) and implantable cardioverter defibrillator (ICD) for secondary prophylaxis.</AbstractText>Between 1994 and 2007, 160 consecutive patients with DCM and spontaneous sustained VT/VF or cardiac arrest underwent PVS prior to ICD implantation. Outcome data, particularly probability of survival without (sudden) death or appropriate ICD therapies for fast VT, were assessed during long-term follow-up. PVT/VF was induced in 50 (31%) and SMVT in 30 (19%) patients. During a mean follow-up of 53 +/- 15 months, we observed 19/50 (38%), 10/30 (33%), and 14/80 (18%) deaths in the PVT/VF, SMVT, and non-inducible group, respectively. These deaths were sudden in 7/50 (14%), 2/30 (7%), and 0/80 (0%) of patients, respectively. At least one fast VT was treated by the ICD in 26/50 (52%), 6/30 (20%), and 22/80 (28%) patients, respectively. PVT/VF but not SMVT-inducible patients had a significantly worse overall survival (log-rank P = 0.013), survival without sudden cardiac death (P < 0.01), or survival without fast VT (P < 0.01) according to Kaplan-Meier method than non-inducible patients. Additionally, survival free of fast VT was significantly worse in PVT/VF vs. SMVT-inducible patients (P < 0.01).</AbstractText>Inducibility of PVT/VF is a much stronger predictor of recurrences of fast VT as opposed to SMVT induction in DCM patients with ICD for secondary prevention.</AbstractText> |
7,087 | [Experiences on surgical treatment of severe aortic valve stenosis: a report of 171 cases]. | To analyze the experiences on surgical treatment of severe aortic valve stenosis.</AbstractText>From December 1990 to December 2006, 171 patients with severe aortic valve stenosis underwent aortic valve replacement (AVR). There were 135 males and 36 females aged from 10 to 75 years old, with a mean of (45.8 +/- 15.6) years old. The intervals between the first episode of exertion dyspnea and administration to operation were 2 months to 52 years. The pathological lesions of the group were rheumatic aortic valve stenosis in 75 cases, calcified aortic stenosis in 66 cases, bicuspid aortic valve in 26 cases and other congenital aortic valve stenosis in 4 cases. One hundred and twenty-four patients underwent AVR, 7 AVR combined with replacement of the ascending aorta, 5 AVR with coronary artery bypass grafting, 19 AVR with mitral valve plasty (MVP), 8 AVR with plasty of the ascending aorta and 8 AVR with enlargement of the aortic root.</AbstractText>The averaged operation time was (4.4 +/- 0.6) h. Cardiopulmonary bypass (CPB) time was (124.7 +/- 38.5) min and the aorta clamp time was (78.3 +/- 21.7) min. The averaged blood loss during operation was (754.5 +/- 518.4) ml. All the procedures were successfully performed and all patients were weaned off CPB uneventfully. The indication of early complications was 12.3% (21/171), including low cardiac output syndrome in 7 cases, multi-organ failure in 3 cases, endocarditis in 1 case, renal dysfunction in 4 cases, ventricular fibrillation in 1 case, excessive bleeding in 2 cases, III atrial-ventricular block in 2 cases, and mediastinal infection in 1 case. The total mortality was 5.8% (10/171) with the main causes as cardiac failure for 4 cases, arrhythmia for 1 case, multi-organ failure for 4 cases, and infectious endocarditis for 1 case.</AbstractText>Successful management of severe aortic valve stenosis requires sophisticated surgical techniques and experienced peri-operative care. Satisfactory results can be achieved if valve replace surgery is performed adequately.</AbstractText> |
7,088 | The intriguing problem of atrial fibrillation in competitive athletes. | Atrial fibrillation (AF) is the most frequent cause of prolonged palpitations in young competitive athletes, even including those performing elite sport activity. This arrhythmia may occasionally affect impair athletes' ability to compete thus leading to non-eligibility at prequalification screening. Competitive sport has a significant impact on the autonomous nervous system. In fact, long-term regular intense physical training determines an increase in vagal tone leading to resting bradycardia. During physical activity, particularly in the setting of competition, a marked release of catecholamines occurs as a result of both the intense physical effort and emotional stress. Both of these adaptive phenomena may precipitate AF. Furthermore, in several athletes with AF an association with sick sinus syndrome has been found, even though the pathophysiological basis of this finding is not clear. This picture is further complicated by the increasingly intake of illicit substances, whose arrhythmogenic effect has been shown both at the ventricular and atrial levels. Moreover, the use of recreational drugs, such as amphetamines, ecstasy, alcohol, cannabinoids, cocaine and so called new drugs in clubs has dramatically increased, with several cases of drug-induced arrhythmic events. These effects are often exacerbated by the combined use of different drugs, especially in situations such as sports competitions, in which the adrenergic system is already hyperactivated. No data have been published on the efficacy of antiarrhythmic therapy in athletes with AF, but it has been reported that athletes are more predisposed to the development of pro-arrhythmic effects induced by antiarrhythmic drugs when compared to general population. Most recently, radiofrequency catheter ablation involving electrical disconnection of the pulmonary veins in athletes with AF limiting their normal training activity and participation in sports competitions has proven highly effective to restore stable sinus rhythm and enable subsequent re-eligibility. |
7,089 | The significance of cardiac sympathetic nervous system abnormality in the long-term prognosis of patients with a history of ventricular tachyarrhythmia. | Severe left ventricular dysfunction or cardiac sympathetic nervous system (SNS) abnormality predicts cardiac death in various heart diseases, including arrhythmogenic disorders. However, it is not clear whether SNS abnormality predicts sudden cardiac death during long-term follow-up in patients with a history of ventricular tachyarrhythmia. We hypothesized that SNS abnormality would be associated with recurrent ventricular arrhythmic events.</AbstractText>123I-metaiodobenzylguanidine (MIBG) scintigraphy was performed on 86 patients (mean age+/-SD, 46+/-19 y, 65.1% men) with a history of ventricular tachycardia or fibrillation. 123I-MIBG (111 MBq) was intravenously administered under resting conditions, and planar images were obtained 15 min and 4 h later (anterior view for 6 min; 512x512 matrices; zoom ratio, 1.0). SNS activity was assessed using the heart-to-mediastinum ratio on delayed imaging.</AbstractText>During about 11 y of follow-up (mean+/-SD, 5.2+/-3.7 y), 3 patients (3.5%) had sudden cardiac death and 21 patients (24.4%) had sustained ventricular tachyarrhythmic events. SNS abnormality, defined as a heart-to-mediastinum ratio of less than 2.8, and left ventricular dysfunction, defined as a left ventricular ejection fraction of less than 50%, were associated with sudden cardiac death or recurrent ventricular tachyarrhythmic events (18/40 patients [45%] with SNS abnormality, vs. 6/46 patients [13%] without, P=0.004; 9/15 patients [60%] with left ventricular dysfunction, vs. 15/71 patients [21.1%] without, P=0.008). After adjustment for potential confounding variables such as age, sex, coronary risk factors, medication use, history of structural heart disease, and left ventricular function, SNS abnormality was a powerful predictor of recurrent arrhythmic events, with a hazard ratio of 3.6 [95% confidence interval, 1.4-9.2, P=0.007]). Further, SNS abnormality had incremental and additive prognostic power in combination with left ventricular dysfunction, with an adjusted hazard ratio of 4.4 [95% confidence interval, 1.9-9.9, P<0.0001]).</AbstractText>SNS abnormality predicted recurrent ventricular tachyarrhythmic events during long-term follow-up. 123I-MIBG scintigraphic evaluations for SNS abnormality may be an option for screening patients at high risk for sudden cardiac death.</AbstractText> |
7,090 | Timing of defibrillation shocks for resuscitation of rapid ventricular tachycardia: does it make a difference? | Under current resuscitation guidelines symptomatic ventricular tachycardia (VT) with a palpable pulse is treated with synchronised cardioversion to avoid inducing ventricular fibrillation (VF), whilst pulseless VT is treated as VF with rapid administration of full defibrillation energy unsynchronised shocks. The additional delay in setting up the ECG to provide accurate synchronisation has been the main reason for advocating this approach, although many current defibrillators allow accurate synchronisation via just the adhesive defibrillator pads. The aim of this study was to investigate whether the timing of defibrillatory shocks in rapid VT-affected resuscitation outcome. The timings of the shocks relative to the QRS complex were used to define whether each shock was acting as a 'synchronised' or 'unsynchronised' shock. The study was a retrospective review of all diagnostic electrophysiological studies performed at Papworth Hospital. A total of 271 studies for ventricular arrhythmias were identified, with 144 studies resulting in stable monomorphic VT being induced. Of these VT episodes, 40 stopped spontaneously, 61 cases were terminated with anti-tachycardia pacing, 1 required cardioversion for slow but incessant VT and 42 required defibrillation for severe haemodynamic compromise/cardiac arrest. The electronic recordings of the defibrillation episodes were analysed to investigate the effects of shock timing on outcome. Of the 42 patients who required defibrillation, 30 had shocks delivered within a 100 ms window of the peak of the QRS complex. Of these, 28 patients converted to a perfusing rhythm and 2 patients deteriorated from VT to VF as a result of the defibrillation shock. The remaining 12 patients received shocks outside this window, with 5 converting to a perfusing rhythm and 7 deteriorating to VF. Defibrillator shocks within the QRS complex had a success rate of 93% compared to a success rate of 42% for outside the QRS complex (p=0.0016 two-tailed Fishers' exact test, odds ratio=19.6, 95% limits=3.1-123.1). There was no significant effect of age or sex of the patient, the underlying heart disease, rate of VT or anti-arrhythmic medication on the outcome, although the number of patients was too small to definitively exclude this. Therefore, defibrillation shocks delivered shortly after the peak of the QRS complex in rapid VT do appear to offer significant advantages over defibrillation shocks at other parts of the cardiac cycle for very rapid ventricular tachycardia. |
7,091 | Multiple cardiac thrombi and thromboembolism in a heparin-induced thrombocytopenia antibody-positive patient with heart failure. | A 49-year-old Japanese man presented with orthopnea and edema in both legs. He was diagnosed with congestive heart failure with triple-vessel coronary artery disease. Low antithrombin and left ventricular systolic dysfunction were possible causes of his hypercoagulable state. Echocardiography revealed thrombi in the left ventricle and left trium, poor left ventricular contractility, and a normal mitral valve. Electrocardiogram revealed normal sinus rhythm. We found small infarctions of the brain and spleen in the computed tomography. The heparin treatment of cardiac thrombi is useless because the patient had heparin-induced thrombocytopenia antibody. We removed thrombi in the left ventricle and left atrium by thrombectomy and performed coronary artery bypass graft. Warfarin was administered for anticoagulation. He recovered completely and is now doing well. Our experience indicates that poor cardiac function can together cause multiple cardiac thrombi and subsequent thromboembolism without mitral stenosis or atrial fibrillation. |
7,092 | Sex differences in the hypertensive population with chronic ischemic heart disease. | Cardiopatía Isquémica Crónica e Hipertensión Arterial en la Práctica Clínica en España (CINHTIA) was a survey designed to assess the clinical management of hypertensive outpatients with chronic ischemic heart disease. Sex differences were examined. Blood pressures (BP) was considered controlled at levels of <140/90 or <130/80 mm Hg in diabetics (European Society of Hypertension/European Society of Cardiology 2003); low-density lipoprotein cholesterol (LDL-C) was considered controlled at levels <100 mg/dL (National Cholesterol Education Program Adult Treatment Panel III). In total, 2024 patients were included in the study. Women were older, with a higher body mass index and an increased prevalence of atrial fibrillation. Dyslipidemia, smoking, sedentary lifestyle, and peripheral arterial disease were more frequent in men. In contrast, diabetes, left ventricular hypertrophy, and heart failure were more common in women. BP and LDL-C control rates, although poor in both groups, were better in men (44.9% vs 30.5%, P<.001 and 33.0% vs 25.0%, P<.001, respectively). Stress testing and coronary angiography were more frequently performed in men. |
7,093 | Therapeutic hypothermia in Italian intensive care units: a national survey. | The aim of this study was to investigate the use of therapeutic hypothermia (TH) in Italian Intensive Care Units (ICUs).</AbstractText>After being contacted by phone, a structured questionnaire to evaluate the use of TH was sent to all Italian ICUs. The questionnaire was aimed at determining the extent of TH use (indications, methods employed, target temperature, side effects) as well as the reasons why some ICUs did not make use of TH for the treatment of cardiac arrest patients.</AbstractText>Out of the 448 ICUs contacted, 90% (n=404) returned the questionnaire completely filled in. Sixty-six responders (16%) made use of TH for post-resuscitation care, and 4% used TH for other clinical scenarios (10 ICUs for traumatic brain injury; 5 ICUs for other reasons). More than half used TH not only for cardiac arrest subsequent to ventricular fibrillation (VF), but also for non-VF cardiac arrest with the duration of TH treatment being within the time suggested by advanced cardiac life support guidelines. On the other hand, 80% of questionnaire responders did not use TH, mainly because they felt they did not have enough data/experience (45%), or simply because they had never thought about it (18%).</AbstractText>Despite authoritative data supporting its effectiveness and safety, use of TH as part of the therapy in a post-resuscitation period in Italian ICUs remains low. The reasons for not using it are not completely justified and suggest that an educational program is advisable in order to boost the utilization of TH in Italy.</AbstractText> |
7,094 | Biophysical characterization of the short QT mutation hERG-N588K reveals a mixed gain-and loss-of-function. | The short QT syndrome is a newly discovered pro-arrhythmic condition, which may cause ventricular fibrillation and sudden death. Short QT can originate from the apparent gain-of-function mutation N588K in the hERG potassium channel that conducts repolarising I(Kr) current. The present study describes a profound biophysical characterization of HERG-N588K revealing both loss-of-function and gain-of-function properties of the mutant. Experiments were conducted after heterologous expression in both Xenopus laevis oocytes and mammalian cells and at both room temperature and at 37 degrees C. Also the impact of the beta-subunits KCNE2 was investigated. The most prominent loss-of-function property of HERG-N588K was reduced tail currents but also the activation properties was compromised. Based on these biophysical results we suggest that the general view of HERG-N588K being a gain-of-function is modified to a mixed gain- and loss-of-function mutation. This might also have impact on the pathological picture of the HERG-N588K channels ability to trigger arrhythmic events. |
7,095 | Levosimendan and calcium sensitization of the contractile proteins in cardiac muscle: impact on heart failure. | Levosimendan increases the sensitivity of the cardiac fibrils to calcium, favorably affects hemodynamics in patients with heart failure. It is a positive inotrope and a peripheral vasodilator. The elimination half-life of the compound is about 1 hour. The drug decreases pulmonary capillary wedge pressure, increases cardiac output with the improvement in left ventricular ejection fraction leading to symptomatic improvement which includes decreased dyspnea and fatigue. Levosimendan can be used safely with diuretics, nitrates, beta-blockers, digoxin, and angiotensin-converting enzyme inhibitors. The most common adverse effects of levosimendan are headache and hypotension. Prolongation of the QTc interval does not appear to increase the incidence of arrhythmias, including ventricular tachycardia, ventricular fibrillation, and torsades de pointes. Levosimendan is a novel agent in the treatment of decompensated heart failure, representing a newer class of medications aimed at increasing calcium sensitivity. Its properties holds promise for the treatment of heart failure but further large-scale studies will be needed to determine its precise efficacy, safety, as well as the compound's long-term impact on mortality. |
7,096 | [Arterial hypertension and cardiac arrhythmias]. | VENTRICULAR ARRHYTHMIAS: Different factors--like hypertrophy, fibrosis, ischemia and apoptosis increase the risk of ventricular arrhythmias and sudden arrhythmic death. ACE inhibitors and Angiotensin receptor antagonists offer a curative therapeutic approach. Beta-blocker are strongly recommended. Amiodarone may be used for symptomatic arrhythmia suppression--but with no proven favourable prognostic effect. The use of class-1 antiarrhythmic drugs is obsolete in the presence of left ventricular hypertrophy and heart failure. Implantable cardioverter/defibrillators (ICD) have been proven to have a positive effect on survival in secondary and primary prevention of sudden cardiac death, and so has cardiac synchronization in severe cardiac dysfunction and widened QRS complex. Atrial fibrillation (AF): Arterial hypertension represents the main risk factor for AF. Patients' age, left ventricular hypertrophy, left atrial dilatation and angiotensin-II activation play an important role in the induction and maintenance of AF. Angiotensin-receptor and beta-blockers seem to be efficacious in AF suppression and also on the regression of hypertrophy. The use of antiarrhythmic agents (AA) is limited because of their relatively low long-term efficacy and pro-arrhythmia properties. Best results may be achieved with class 1C AA drugs in patients with no or minimal structural heart disease. In all other cases amiodarone is suitable but is limited by its side effects. In patients with no or only a few symptoms rate control may be sufficient, but if there are symptoms interventional left atrial ablation of pulmonary veins should be attempted as a real curative strategy. |
7,097 | Atrial-selective effects of chronic amiodarone in the management of atrial fibrillation. | Although amiodarone is one of the most effective pharmacologic agents used in clinical management of atrial fibrillation (AF), little is known about its differential effects in atrial and ventricular myocardium.</AbstractText>This study sought to compare the electrophysiological effects of chronic amiodarone in atria and ventricles.</AbstractText>We compared the electrophysiological characteristics of coronary-perfused atrial and ventricular wedge preparations isolated from untreated and chronic amiodarone-treated dogs (amiodarone, 40 mg/kg/day for 6 weeks, n = 12).</AbstractText>Chronic amiodarone prolonged action potential duration (APD(90)) predominantly in atria compared to ventricles and prolonged the effective refractory period (ERP) more than APD(90) in both ventricular and atrial preparations (particularly in the latter) due to the development of postrepolarization refractoriness. Amiodarone reduced dispersion of APD(90) in both atria and ventricles. Although the maximum rate of increase of the action potential upstroke (V(max)) was significantly lower in both atria and ventricles of amiodarone-treated hearts versus untreated controls, the reduction of V(max) was much more pronounced in atria. Amiodarone prolonged P-wave duration more significantly than QRS duration, reflecting greater slowing of conduction in atria versus ventricles. These atrioventricular distinctions were significantly accentuated at faster activation rates. Persistent acetylcholine-mediated AF could be induced in only 1 of 6 atria from amiodarone-treated versus 10 of 10 untreated dogs.</AbstractText>Our results indicate that under the conditions studied, chronic amiodarone has potent atrial-predominant effects to depress sodium channel-mediated parameters and that this action of the drug is greatly potentiated by its ability to prolong APD predominantly in the atria, thus contributing to its effectiveness to suppress AF.</AbstractText> |
7,098 | Role of late sodium current in modulating the proarrhythmic and antiarrhythmic effects of quinidine. | Quinidine is used to treat atrial fibrillation and ventricular arrhythmias. However, at low concentrations, it can induce torsade de pointes (TdP).</AbstractText>The purpose of this study was to examine the role of late sodium current (I(Na)) as a modulator of the arrhythmogenicity of quinidine in female rabbit isolated hearts and cardiomyocytes.</AbstractText>Epicardial and endocardial monophasic action potentials (MAPs), ECG signals, and ion channel currents were measured. The sea anemone toxin ATX-II was used to increase late I(Na).</AbstractText>Quinidine had concentration-dependent and often biphasic effects on measures of arrhythmogenicity. Quinidine increased the duration of epicardial MAP (MAPD(90)), QT interval, transmural dispersion of repolarization (TDR), and ventricular effective refractory period. Beat-to-beat variability of MAPD(90) (BVR), the interval from peak to end of the T wave (Tpeak-Tend) and index of Tpeak-Tend/QT interval were greater at 0.1 to 3 micromol/L than at 10-30 micromol/L quinidine. In the presence of 1 nmol/L ATX-II, quinidine caused significantly greater concentration-dependent and biphasic changes of Tpeak-Tend, TDR, BVR, and index of Tpeak-Tend/QT interval. Quinidine (1 micromol/L) induced TdP in 2 and 13 of 14 hearts in the absence and presence of ATX-II, respectively. Increases of BVR, index of Tpeak-Tend/QT interval, and Tpeak-Tend were associated with quinidine-induced TdP. Quinidine inhibited I(Kr), peak I(Na), and late I(Na) with IC(50)s of 4.5 +/- 0.3 micromol/L, 11.0 +/- 0.7 micromol/L, and 12.0 +/- 0.7 micromol/L.</AbstractText>Quinidine had biphasic proarrhythmic effects in the presence of ATX-II, suggesting that late I(Na) is a modulator of the arrhythmogenicity of quinidine. Enhancement of late I(Na) increased proarrhythmia caused by low but not high concentrations of quinidine.</AbstractText> |
7,099 | Prevalence of early repolarization pattern in inferolateral leads in patients with Brugada syndrome. | Recent data have shown a high incidence of the early repolarization pattern confined in inferolateral leads in patients with idiopathic ventricular fibrillation.</AbstractText>The purpose of the present study was to investigate the prevalence and the prognostic significance of the early repolarization pattern in inferolateral leads in patients with Brugada syndrome.</AbstractText>Clinical, genetic, and electrophysiologic data from 290 individuals (223 males, mean age 48.3 +/- 14.2 years) with a spontaneous or drug-induced type 1 electrocardiogram (ECG) pattern of Brugada syndrome and structurally normal hearts were analyzed. Twelve-lead ECGs were evaluated for the presence of early repolarization pattern, which was defined as J-point elevation of at least 0.1 mV from baseline in at least two inferior or lateral leads. Follow-up data were obtained for all subjects.</AbstractText>An early repolarization pattern manifested as notched or slurred J-point elevation mainly in lateral leads was observed in 35 subjects (12%). The prevalence of the early repolarization pattern was significantly higher in male subjects (P = .004). During a mean follow-up period of 44.9 +/- 27.5 months, 22 subjects (8%) displayed an arrhythmic event including sudden cardiac death. There were no significant differences regarding spontaneous ECG type of Brugada syndrome, symptoms, family history of sudden cardiac death, and positive genetic test between subjects with and without the early repolarization pattern. The presence of early repolarization pattern was not associated with arrhythmic events during follow-up (Hazard ratio [HR] 1.090; 95% confidence interval 0.349-3.403; P = .882).</AbstractText>The early repolarization pattern in inferolateral leads is not an uncommon finding in Brugada syndrome. In our population, the early repolarization features were not associated with a worse outcome in subjects with Brugada syndrome.</AbstractText> |
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