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6,900 | A simplified clinical electrocardiogram score for the prediction of cardiovascular mortality. | Electrocardiogram (ECG) scores have been demonstrated to predict CV mortality but they are rarely utilized clinically.</AbstractText>Develop a simple score consisting of adding classical ECG abnormalities to make the ECG a more convenient prognostic tool.</AbstractText>Resting ECGs of 29,320 outpatient male veterans from the Palo Alto Veteran Affairs Healthcare System (PAVHS) collected between 1987 and 2000 were computer analyzed with an average follow-up of 7.5 y. Twelve classic ECG abnormalities were chosen on the basis of prevalence and corresponding relative risks, including left and right bundle branch block, diagnostic Q waves, intraventricular conduction defect, atrial fibrillation, left atrial abnormality, left and right axis deviation, left and right ventricular hypertrophy, ST depression, and abnormal QTc interval. A simple score derived from the summation of these criteria was then entered into an age and heart rate adjusted Cox analysis.</AbstractText>There was a progressive increase in risk of death as the number of ECG abnormalities increased. The relative risks for 1, 2, 3, 4, and 5 ECG abnormalities were 1.8 (CI 1.6-2.0), 2.4 (CI 2.2-2.7), 3.6 (CI 3.2-4.1), 4.5 (CI 3.8-5.4), and 6.0 (CI 4.7-7.8) respectively (p < 0.001). The age-adjusted hazard ratio for CV mortality was 6.0 when there were five or more ECG abnormalities present.</AbstractText>Summing the number of classical ECG abnormalities provides a powerful predictor of CV mortality independent of age, standard risk factors, and clinical status.</AbstractText> |
6,901 | Effects of interventional lung assist on haemodynamics and gas exchange in cardiopulmonary resuscitation: a prospective experimental study on animals with acute respiratory distress syndrome. | Interventional lung assist (ILA), based on the use of a pumpless extracorporeal membrane oxygenator, facilitates carbon dioxide (CO2) elimination in acute respiratory distress syndrome (ARDS). It is unclear whether an ILA system should be clamped during cardiopulmonary resuscitation (CPR) in patients with ARDS or not. The aim of our study was to test the effects of an ILA on haemodynamics and gas exchange during CPR on animals with ARDS and to establish whether the ILA should be kept open or clamped under these circumstances.</AbstractText>The study was designed to be prospective and experimental. The experiments were performed on 12 anaesthetised and mechanically ventilated pigs (weighing 41 to 58 kg). One femoral artery and one femoral vein were cannulated and connected to an ILA. ARDS was induced by repeated bronchoalveolar lavage. An indwelling pacemaker was used to initiate ventricular fibrillation and chest compressions were immediately started and continued for 30 minutes. In six animals, the ILA was kept open and in the other six it was clamped.</AbstractText>Systolic and mean arterial pressures did not differ significantly between the groups. With the ILA open mean +/- standard deviation systolic blood pressures were 89 +/- 26 mmHg at 5 minutes, 71 +/- 28 mmHg at 10 minutes, 63 +/- 33 mmHg at 20 minutes and 83 +/- 23 mmHg at 30 minutes. The clamped ILA system resulted in systolic pressures of 77 +/- 30 mmHg, 90 +/- 23 mmHg, 72 +/- 11 mmHg and 72 +/- 22 mmHg, respectively. In the group with the ILA system open, arterial partial pressure of CO2 was significantly lower after 10, 20 and 30 minutes of CPR and arterial partial pressure of oxygen was higher 20 minutes after the onset of CPR (191 +/- 140 mmHg versus 57 +/- 14 mmHg). End-tidal partial pressure of CO2 decreased from 46 +/- 23 Torr (ILA open) and 37 +/- 9 Torr (ILA clamped) before intervention to 8 +/- 5 Torr and 8 +/- 10 Torr, respectively, in both groups after 30 minutes of CPR.</AbstractText>Our results indicate that in an animal model of ARDS, blood pressures were not impaired by keeping the ILA system open during CPR compared with the immediate clamping of the ILA with the onset of CPR. The effect of ILA on gas exchange implied a beneficial effect.</AbstractText> |
6,902 | Frequency analysis of atrial electrograms identifies conduction pathways from the left to the right atrium during atrial fibrillation-studies in two canine models. | Studies of atrial fibrillation (AF) have demonstrated that a stable rhythm of very short cycle length in the left atrium (LA) can cause fibrillatory conduction in the rest of the atria. We tested the hypothesis that fast Fourier transform (FFT) analysis of atrial electrograms (AEGs) during this AF will rapidly and reliably identify LA-to-right atrium (RA) conduction pathway(s) generated by the driver.</AbstractText>During induced atrial tachyarrhythmias in the canine sterile pericarditis and rapid ventricular pacing-induced congestive heart failure models, 380-404 AEGs were recorded simultaneously from epicardial electrodes on both atria. FFT analysis of AEGs during AF demonstrated a dominant frequency peak in the LA (driver), and multiple frequency peaks in parts of the LA and the most of the RA. Conduction pathways from the LA driver to the RA varied from study-to-study. They were identified by the presence of multiple frequency peaks with one of the frequency peaks at the same frequency as the driver, and traveled (1) inferior to the inferior vena cava (IVC); (2) between the superior vena cava and the right superior pulmonary vein (RSPV); (3) between the RSPV and the right inferior pulmonary vein (RIPV); (4) between the RIPV and the IVC; and (5) via Bachmann's bundle. Conduction pathways identified by FFT analysis corresponded to the conduction pathways found in classical sequence of activation mapping. Computation time for FFT analysis for each AF episode took less than 5 minutes.</AbstractText>FFT analysis allowed rapid and reliable detection of the LA-to-RA conduction pathways in AF generated by a stable and rapid LA driver.</AbstractText> |
6,903 | Liver transplantation in a patient with propionic acidemia requiring extra corporeal membrane oxygenation during severe metabolic decompensation. | LDLT is an effective treatment modality in patients with congenial metabolic liver disease. PA is a rare autosomal recessive disorder caused by deficiency in propionyl-CoA carboxylase. The present study demonstrates a two-yr-old girl with PA who was admitted for metabolic decompensation and immediately treated with CHD and protein intake restriction at 46 days of age. Two yr later, the patient was readmitted for severe metabolic decompensation with complete atrioventricular block and ventricular fibrillation. CHDF and ECMO were indicated because of progressive metabolic and cardiac deterioration. After full recovery of the ejection fraction, planned LDLT was performed to prevent further metabolic decompensation and fatal cardiac insufficiency. No significant events occurred after the operation and the condition of the patient is stable with continued protein restriction and carnitine supplementation. |
6,904 | Magnesium sulfate versus placebo for paroxysmal atrial fibrillation: a randomized clinical trial. | The objective was to investigate the efficacy of magnesium sulfate (MgSO4) in decreasing the ventricular rate in emergency department (ED) patients presenting with new-onset, rapid atrial fibrillation (AF).</AbstractText>A double-blinded, placebo-controlled randomized clinical trial was conducted in an adult university hospital. Patients aged > or =18 years with AF onset of less than 48 hours and a sustained ventricular rate of >100 beats/min were randomized to either intravenous (IV) MgSO4 10 mmol or normal saline (NSal). Rhythm and instantaneous heart rate as measured by the monitor were recorded at baseline and every 15 minutes for 2 hours after starting the trial drug. Heart rate and rhythm were compared at 2 hours. A multilevel modeling analysis was performed to adjust for differences in baseline heart rate and any additional treatment and to examine changes in heart rate over time.</AbstractText>Twenty-four patients were randomized to MgSO4 and 24 to NSal. Baseline heart rate was lower in the MgSO4 group (mean +/- standard deviation [+/-SD] = 125 +/- 24 vs. 140 +/- 21 beats/min]. One and 3 patients in the MgSO4 and NSal groups, respectively, were given another antiarrhythmic or were electrically cardioverted within 2 hours after starting the trial drug. Heart rate (mean +/- SD) at 2 hours in both MgSO4 (116 +/- 30 beats/min) and NSal groups (114 +/- 31 beats/min) decreased below their respective baseline levels. However, the rate of heart rate decrease across time did not differ between groups (p = 0.124). The proportion of patients who converted to sinus rhythm 2 hours post-trial drug did not differ (MgSO4 8.7% vs. NSal 25.0%, p = 0.25).</AbstractText>This study was unable to demonstrate a difference between IV MgSO4 10 mmol and saline placebo for reducing heart rate or conversion to sinus rhythm at 2 hours posttreatment in ED patients with AF of less than 48 hours duration.</AbstractText> |
6,905 | [Tricuspid annuloplasty, pulmonary valve replacement, ventricular septal defect (VSD) patch closure, and right-sided maze procedure 23-years after corrective repair of tetralogy of Fallot]. | Postoperative pulmonary valve regurgitation, stenosis of the right ventricular outflow tract, conduit failure, ventricular septal patch leak, secondary tricuspid valve regurgitation, and various arrhythmias are the major complications that develop after surgical repair of tetralogy of Fallot in adults. A 27-year-old male with pulmonary regurgitation, tricuspid regurgitation, residual ventricular septal defect (VSD), low left ventricular function, and chronic atrial fibrillation underwent tricuspid annuloplasty, pulmonary valve replacement with a stentless aortic valve, VSD patch closure, and right-sided maze procedure, and the postoperative course was uneventful. The cardiothoracic ratio decreased, sinus rhythm was restored, and the patient's complaints were relieved. Reoperation at the optimal time after corrective repair of tetralogy of Fallot in adults may improve the outcome. |
6,906 | MinK-dependent internalization of the IKs potassium channel. | KCNQ1-MinK potassium channel complexes (4alpha:2beta stoichiometry) generate IKs, the slowly activating human cardiac ventricular repolarization current. The MinK ancillary subunit slows KCNQ1 activation, eliminates its inactivation, and increases its unitary conductance. However, KCNQ1 transcripts outnumber MinK transcripts five to one in human ventricles, suggesting KCNQ1 also forms other heteromeric or even homomeric channels there. Mechanisms governing which channel types prevail have not previously been reported, despite their significance: normal cardiac rhythm requires tight control of IKs density and kinetics, and inherited mutations in KCNQ1 and MinK can cause ventricular fibrillation and sudden death. Here, we describe a novel mechanism for this control.</AbstractText>Whole-cell patch-clamping, confocal immunofluorescence microscopy, antibody feeding, biotin feeding, fluorescent transferrin feeding, and protein biochemistry techniques were applied to COS-7 cells heterologously expressing KCNQ1 with wild-type or mutant MinK and dynamin 2 and to native IKs channels in guinea-pig myocytes. KCNQ1-MinK complexes, but not homomeric KCNQ1 channels, were found to undergo clathrin- and dynamin 2-dependent internalization (DDI). Three sites on the MinK intracellular C-terminus were, in concert, necessary and sufficient for DDI. Gating kinetics and sensitivity to XE991 indicated that DDI decreased cell-surface KCNQ1-MinK channels relative to homomeric KCNQ1, decreasing whole-cell current but increasing net activation rate; inhibiting DDI did the reverse.</AbstractText>The data redefine MinK as an endocytic chaperone for KCNQ1 and present a dynamic mechanism for controlling net surface Kv channel subunit composition-and thus current density and gating kinetics-that may also apply to other alpha-beta type Kv channel complexes.</AbstractText> |
6,907 | Retrograde flush following warm ischemia in the non-heart-beating donor results in superior graft performance at reperfusion. | The use of non-heart-beating donors (NHBD) has been propagated as an alternative to overcome the scarcity of pulmonary grafts. The presence of postmortem thrombi, however, is a concern for the development of primary graft dysfunction. In this isolated lung reperfusion study, we looked at the need and the best route of preharvest pulmonary flush.</AbstractText>Domestic pigs were sacrificed by ventricular fibrillation and divided in 3 groups (n = 6 per group). After 1 h of in situ warm ischemia, lungs in group I were retrieved unflushed (NF). In group II, lungs were explanted after an anterograde flush (AF) through the pulmonary artery. Finally, in group III, lungs were explanted after a retrograde flush (RF) via the left atrium. After 3 h of cold storage, the left lung was assessed for 60 min in our ex vivo reperfusion model. Wet-to-dry weight ratio (W/D) was calculated after reperfusion.</AbstractText>Pulmonary vascular resistance (dynes x sec x cm(-5)) was 1145 +/- 56 (RF) versus 1560 +/- 123 (AF) and 1435 +/- 95 (NF) at 60 min of reperfusion (P < 0.05). Oxygenation and compliance were higher and plateau airway pressure was lower in RF versus AF and NF, although the difference did not reach statistical significance. No differences in W/D were observed between groups after reperfusion. Histological examination revealed fewer microthrombi in the left lung in RF compared with AF and NF.</AbstractText>RF of lungs from NHBD improves graft function by elimination of microthrombi from the pulmonary vasculature, resulting in lower pulmonary vascular resistance upon reperfusion.</AbstractText> |
6,908 | Development of the probability of return of spontaneous circulation in intervals without chest compressions during out-of-hospital cardiac arrest: an observational study. | One of the factors that limits survival from out-of-hospital cardiac arrest is the interruption of chest compressions. During ventricular fibrillation and tachycardia the electrocardiogram reflects the probability of return of spontaneous circulation associated with defibrillation. We have used this in the current study to quantify in detail the effects of interrupting chest compressions.</AbstractText>From an electrocardiogram database we identified all intervals without chest compressions that followed an interval with compressions, and where the patients had ventricular fibrillation or tachycardia. By calculating the mean-slope (a predictor of the return of spontaneous circulation) of the electrocardiogram for each 2-second window, and using a linear mixed-effects statistical model, we quantified the decline of mean-slope with time. Further, a mapping from mean-slope to probability of return of spontaneous circulation was obtained from a second dataset and using this we were able to estimate the expected development of the probability of return of spontaneous circulation for cases at different levels.</AbstractText>From 911 intervals without chest compressions, 5138 analysis windows were identified. The results show that cases with the probability of return of spontaneous circulation values 0.35, 0.1 and 0.05, 3 seconds into an interval in the mean will have probability of return of spontaneous circulation values 0.26 (0.24-0.29), 0.077 (0.070-0.085) and 0.040(0.036-0.045), respectively, 27 seconds into the interval (95% confidence intervals in parenthesis).</AbstractText>During pre-shock pauses in chest compressions mean probability of return of spontaneous circulation decreases in a steady manner for cases at all initial levels. Regardless of initial level there is a relative decrease in the probability of return of spontaneous circulation of about 23% from 3 to 27 seconds into such a pause.</AbstractText> |
6,909 | Waivers for cardiovascular diseases in military aircrew: differences between Japanese and U.S. protocols. | Cardiovascular diseases can cause sudden incapacitation in aircrew. Cardiological diagnosis and therapy have changed a great deal in recent decades, as with coronary revascularization, including percutaneous coronary intervention and coronary artery bypass grafting for coronary artery disease, and electrophysiological studies and radiofrequency catheter ablation (RFCA) for sustained arrhythmias. Physicians need to be able to make appropriate, objective recommendations regarding cardiovascular diseases in an aeromedical waiver system.</AbstractText>We analyzed all 95 waiver cases regarding cardiovascular diseases in the Japan Air Self-Defense Force (JASDF), 1980-2007, and compared them to policies in the United States Air Force (USAF).</AbstractText>The JASDF and the USAF handle most conditions similarly, although there are differences regarding coronary revascularization, atrial fibrillation, non-sustained ventricular tachycardia (nsVT), and hypertrophic cardiomyopathy. The JASDF used RFCA more commonly for the treatment of aircrew with atrial fibrillation and nsVT Although routine follow-up with electrophysiological studies is no longer indicated for Wolff-Parkinson-White and atrioventricular node reentrant tachycardia in USAF policy, the JASDF still conducts reevaluation for all RFCA cases.</AbstractText>This study made recommendations to improve the JASDF waiver system for cardiovascular diseases.</AbstractText> |
6,910 | Pharmacotherapy for atrial arrhythmias: present and future. | Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. It is associated with significant morbidity, including palpitations, exercise intolerance, congestive heart failure, and increased risk of embolic stroke. Mortality is increased twofold in patients with AF. Management of AF with antiarrhythmic drugs traditionally has been hindered by lack of efficacy, poor tolerance of side effects, drug-associated toxicity, and proarrhythmic potential. Improved understanding of atrial electrical and structural remodeling as well as advances in rational drug design have led to new agents that may be superior to their predecessors. New agents that target atrium-specific ion channels limit the potential for ventricular arrhythmias, and less toxic derivatives such as dronedarone may be more tolerable. Drugs with entirely novel mechanisms, such as the gap junction modulator rotigaptide, have shown efficacy in ventricular arrhythmias and have potential for atrial arrhythmias as well. This review discusses recent advances in pharmacotherapy for treatment of atrial arrhythmias. |
6,911 | The renin-angiotensin-aldosterone system (RAAS) and cardiac arrhythmias. | The role of the renin-angiotensin-aldosterone system (RAAS) in many cardiovascular disorders, including hypertension, cardiac hypertrophy, and atherosclerosis, is well established, whereas its relationship with cardiac arrhythmias is a new area of investigation. Atrial fibrillation and malignant ventricular tachyarrhythmias, especially in the setting of cardiac hypertrophy or failure, seem to be examples of RAAS-related arrhythmias because treatment with RAAS modulators, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor blockers, reduces the incidence of these arrhythmias. RAAS has a multitude of electrophysiological effects and can potentially cause arrhythmia through a variety of mechanisms. We review new experimental results that suggest that RAAS has proarrhythmic effects on membrane and sarcoplasmic reticulum ion channels and that increased oxidative stress is likely contributing to the increased arrhythmic incidence. A summary of ongoing clinical trials that will address the clinical usefulness of RAAS modulators for prevention or treatment of arrhythmias is presented. |
6,912 | Cellular bases for human atrial fibrillation. | Atrial fibrillation (AF) causes substantial morbidity and mortality. It may be triggered and sustained by either reentrant or nonreentrant electrical activity. Human atrial cellular refractory period is shortened in chronic AF, likely aiding reentry. The ionic and molecular mechanisms are not fully understood and may include increased inward rectifier K(+) current and altered Ca(2+) handling. Heart failure, a major cause of AF, may involve arrhythmogenic atrial electrical remodeling, but the pattern is unclear in humans. Beta-blocker therapy prolongs atrial cell refractory period; a potentially antiarrhythmic influence, but the ionic and molecular mechanisms are unclear. The search for drugs to suppress AF without causing ventricular arrhythmias has been aided by basic studies of cellular mechanisms of AF. It remains to be seen whether such drugs will improve patient treatment. |
6,913 | Effect of fish oil on ventricular tachyarrhythmia in three studies in patients with implantable cardioverter defibrillators. | To determine the effects of omega-3 polyunsaturated fatty acids (omega-3 PUFAs) from fish on the incidence of recurrent ventricular arrhythmia in implantable cardioverter defibrillator (ICD) patients by combining results from published trials.</AbstractText>We searched in the Medline, EMBASE, and Cochrane databases and performed a meta-analysis on all three available trials on fish oil and ventricular arrhythmia. Furthermore, we pooled individual data of two of these randomized, double-blind, placebo-controlled trials (Raitt et al. Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial. JAMA 2005;293:2884-2891 and Brouwer et al. Effect of fish oil on ventricular tachyarrhythmia and death in patients with implantable cardioverter defibrillators: the Study on Omega-3 Fatty Acids and Ventricular Arrhythmia (SOFA) randomized trial. JAMA 2006;295:2613-2619). The main outcome was time to first confirmed ventricular fibrillation (VF) or ventricular tachycardia (VT) combined with death for the meta-analysis, and time to first spontaneous confirmed VF or VT for the pooled analysis. The meta-analysis (n = 1148) showed no convincing protective effect of fish oil (RR 0.90; 95% CI 0.67-1.22). The hazard ratio for the subgroup of patients with coronary artery disease at baseline (0.79; 0.60-1.06) tended towards a protective effect. The pooled analysis (n = 722) showed that time to appropriate ICD intervention was similar for fish oil and placebo treatment (log-rank P = 0.79).</AbstractText>These findings do not support a protective effect of omega-3 PUFAs from fish oil on cardiac arrhythmia in all patients with an ICD. Current data neither prove nor disprove a beneficial or a detrimental effect for subgroups of patients with specific underlying pathologies.</AbstractText> |
6,914 | [Role of permanent pacing in the prevention and treatment of atrial fibrillation]. | Atrial fibrillation onset is enhanced by the presence of sinus bradycardia and sinus pauses. Cardiac pacing, by avoiding them, may prevent tachyarrhythmias. The atrial-based modes of pacing (AAI or DDD) demonstrated to be superior to ventricular pacing mode (VVI) in terms of reduction of atrial fibrillation burden and thromboembolic consequences of the arrhythmia. Many pacing algorithms have been proposed to ensure the maximum percentage of atrial pacing and to avoid post-extrasystolic pauses, both conditions that are needed to reduce atrial fibrillation burden. Moreover, it has been demonstrated that the efficacy in preventing the arrhythmia is superior if the site of pacing is a critical site for interatrial conduction, like Bachmann bundle or the low interatrial septum at the level of Koch triangle. Finally, also early treatment of the arrhythmia by overdrive or high-frequency pacing may contribute to reduce recurrences. Guidelines that have been published in the last years confirm that atrial-based pacing is effective in preventing atrial fibrillation in sick sinus syndrome, whereas the usefulness of prevention algorithms, alternative sites of pacing and pacing therapies is still under debate and further studies are needed. |
6,915 | [Integrated coronary artery bypass strategy prevents urgent pump conversion during off-pump coronary artery bypass grafting]. | Urgent pump conversion during off-pump coronary artery bypass (OPCAB) results in high morbidity and mortality. We retrospectively evaluated if the peri-operative integrated strategy prevents this lethal event in our 400 consecutive OPCAB operations. The patients with preoperative cardiogenic shock and/or ventricular arrhythmias underwent on-pump coronary artery bypass grafting (CABG). All other patients (99% of total CABG) were scheduled to undergo OPCAB (n=400). Prophylactic intraaortic balloon pumping (IABP) was applied to the patients with critical (>95%) left main trunk stenosis or low (<0.35) left ventricular ejection fraction. All the patients received the deep pericardial suture, apex-traction device, suction-type stabilizer, test-clamp of target coronary arteries by micro bulldog clamp, and intra-coronary shunts. Intra-operative IABP was applied in the case of sustained ST-segment change and/or elevated pulmonary artery pressure. Pump conversion was indicated for the patients with ventricular fibrillation and/or cardiogenic shock. Two patients (0.5%) had pump conversion due to ventricular arrhythmia and sustained hypotension, respectively. These pump conversion did not result in hospital mortality. Three hospital deaths (0.7%) occurred due to non-cardiac causes. The integrated strategy using prophylactic or intra-operative IABP in OPCAB produce a low pump conversion rate even during an early period of surgeon's learning curve. |
6,916 | Acute bioprosthetic thrombosis immediately after aortic valve replacement. | We present the case of a 72-year-old woman referred for dyspnea and vertigo when admitted to the hospital with a diagnosis of aortic stenosis. She had hypertension with previous deep venous thrombosis with no known hypercoagulable diathesis. She underwent aortic valve replacement with a Carpentier-Magna bioprosthesis without intraoperative complications; selective cardioplegia before aortic wall suture confirmed that coronary ostia were free. After extracorporeal circulation weaning, an episode of ventricular fibrillation occurred; sinus rhythm was restored using 20 J shock. Considering new episodes of ventricular fibrillation, the increasing number of polymorph ectopic ventricular systoles and the worsening of patient condition despite the use of high doses of inotropes, an intra-aortic balloon pump 1: 1 was inserted via the right femoral artery. Echocardiography (ECG) did not show alteration of the bioprosthesis in the presence of severe left ventricular impairment (ejection fraction <30%) with ipokinesia of the anterior-lateral wall and moderate-severe mitral regurgitation. Considering the rapid decline of the patient's condition despite the use of high doses of inotropes and an intra-aortic balloon pump, the aortic wall was reopened to control bioprosthesis. The intraoperative finding was unexpected; a thrombus of length 3-4 cm was found, attached to the prosthetic annulus and protruding into the left main trunk. The thrombus was immediately sucked up to avoid coronary embolization and, after that, the prosthesis was replaced with a Mitroflow 19 (Sorin Group Inc, Mitroflow Division, Vancouver, Canada) bioprosthesis. Probably, an association between factors could induce thrombosis-like aortic sinuses: annulus dimensions, endothelium damage caused during decalcification, tears in the bioprosthetic sewing ring, unknown coagulation diathesis and the structure of the Carpentier-Magna support may have induced this very unusual complication. However, we do not have enough information to establish with certainty the causes of this complication, but discussion of this topic may be useful. |
6,917 | Comparison of arterial blood gases of laryngeal mask airway and bag-valve-mask ventilation in out-of-hospital cardiac arrests. | Focusing on the efficacy of successful ventilation during cardiopulmonary resuscitation (CPR) with alternative airways, previous reports investigated various parameters such as success rate, tidal volume, incidence of regurgitation, etc. However, there are few investigations of arterial blood gases (ABG) during CPR with alternative airways, especially the laryngeal mask airway (LMA).</AbstractText>A prospective multicenter study, non-randomized control trial compared ABG on hospital admission of patients resuscitated by emergency medical service personnel with a bag-valve-mask (BVM) with those using a LMA in witnessed cardiac-verified out-of-hospital ventricular fibrillation (VF) or pulseless ventricular tachycardia. According to the Utstein template, 173 cases of LMA and 200 of BVM both placed by paramedics were enrolled. The median arterial pH was statistically higher in the LMA group than in the BVM group (7.117 vs 7.075, P=0.02). There was no difference in the median value of PaCO(2) (52.9 vs 55.3, P=0.06) and PaO(2) (64.6 vs 71.9, P=0.56).</AbstractText>LMA does not greatly benefit the respiratory status of patients such as in this study population. Delayed placement of a LMA will be recommended to achieve minimally interrupted chest compression in an out-of-hospital CPR protocol for witnessed VF cases following shock.</AbstractText> |
6,918 | Assessment of left atrial appendage function with transthoracic tissue Doppler echocardiography. | A transthoracic echocardiographic (TTE) parameter that would stratify atrial fibrillation (AF) risk would be useful. Tissue Doppler imaging can quantify left atrial appendage contraction velocity (LAA A(M)).</AbstractText>We studied 141 patients referred for transoesophageal echocardiogram (TEE); 48 were in AF. We obtained TEE and TTE LAA A(M) velocities from the LAA apex on the parasternal short-axis and apical two-chamber views. Adequate traces were obtained in 118 patients (84%). In these patients, we measured 5382 LAA A(M) velocity tracings. There was a strong correlation between LAA A(M) on TEE and TTE parasternal short-axis (r = 0.741; P < 0.0001) and apical two-chamber views (r = 0.729; P < 0.0001). Patients in AF had lower LAA A(M) than those with sinus rhythm on parasternal short-axis (12 +/- 5 vs. 23 +/- 7 cm/s, P < 0.0001) and apical two-chamber (14 +/- 5 vs. 23 +/- 8 cm/s, P < 0.0001) views. On parasternal short axis, LAA A(M) velocities were lower in patients with spontaneous echo contrast, 11 +/- 4 vs. 22 +/- 8 cm/s (P < 0.0001), and in those with thrombus, 8 +/- 2 cm/s (P < 0.0001). On apical two-chamber, LAA A(M) velocities were also lower with spontaneous echo contrast, 12 +/- 4 vs. 22 +/- 7 cm/s (P < 0.0001), and with thrombus, 10 +/- 4 cm/s (P < 0.0001). In patients with AF and TTE LAA A(M) < or =11 cm/s, we found that nearly one-third had LAA thrombus. In patients with AF and a history of stroke or transient ischaemic attack (TIA), LAA A(M) velocities were lower compared with those without history of stroke or TIA in the parasternal short-axis (9 +/- 3 vs. 13 +/- 5 cm/s, P = 0.02) and apical two-chamber views (11 +/- 3 vs. 15 +/- 6 cm/s, P = 0.008).</AbstractText>Acquiring and quantifying LAA A(M) contraction velocity is feasible on TTE in a high percentage of patients and correlates with TEE. LAA A(M) was lower in AF compared with sinus rhythm, with spontaneous echo contrast compared to without spontaneous echo contrast, and in AF patients with a history of stroke or TIA. Those with LAA thrombus had the lowest LAA A(M) velocities. LAA A(M) is a novel functional parameter that may prove useful for risk stratification of AF.</AbstractText> |
6,919 | Risk stratification of the patients with Brugada type electrocardiogram: a community-based prospective study. | Risk stratification of patients with Brugada electrocardiogram (ECG) is being strongly debated. Conflicting results have been suggested from international registries, which enrolled non-consecutive cases, studied with different programmed electrical stimulation (PES) protocols. The aim of this study was to prospectively evaluate the incidence of arrhythmic events and the prognostic role of clinical presentation, ECG, and of a standardized PES protocol in consecutive cases from a community-based population.</AbstractText>A total of 166 consecutive patients (45 +/- 14 years) with Brugada ECG were enrolled. Type 1 ECG was observed spontaneously in 72 (43%) and after pharmacological testing in 94 (57%). One hundred and three (62%) were asymptomatic, 58 (35%) had syncope, and five (3%) had a prior cardiac arrest. One hundred and thirty-five (81%) underwent PES with two extra stimuli up to ventricular refractoriness and 34% had ventricular fibrillation (VF) induced. Arrhythmic events occurred in nine patients at a mean follow-up of 30 +/- 21 months (2.2 events per 100 person-year): in three (60%) patients with aborted sudden death (aSD), five (8.6%) of those with syncope, and one (1%) of the asymptomatic. The only predictors of events were a history of syncope or aSD (P = 0.02) and induction at PES (P = 0.004).</AbstractText>Clinical presentation is the most important parameter in the risk stratification of patients with Brugada ECG. Programmed electrical stimulation seems valuable, particularly in patients with previous syncope.</AbstractText> |
6,920 | Emergency surgical treatment of advanced endomyocardial fibrosis in Mozambique. | An 11-year-old girl presented to a specialist cardiac facility in Mozambique. She had severe heart failure and massive cardiac enlargement, herniation of the heart into the epigastrium, atrial fibrillation, signs of severe pulmonary hypertension and a low cardiac output.</AbstractText>Chest radiography, echocardiography, 24 h Holter monitoring, and cardiac catheterization.</AbstractText>Left and right endomyocardial fibrosis in conjunction with an aneurysmal left atrium, severe heart failure, and atrial fibrillation.</AbstractText>Left ventricular endocardiectomy with mobilization of the chordae tendineae, mitral valve repair, tricuspid annuloplasty, and left atrial resection.</AbstractText> |
6,921 | Cardiovascular and cerebrovascular comorbidities of hypokalemic and normokalemic primary aldosteronism: results of the German Conn's Registry. | Primary aldosteronism (PA) is associated with vascular end-organ damage.</AbstractText>Our objective was to evaluate differences regarding comorbidities between the hypokalemic and normokalemic form of PA.</AbstractText>This was a retrospective cross-sectional study collected from six German centers (German Conn's registry) between 1990 and 2007.</AbstractText>Of 640 registered patients with PA, 553 patients were analyzed.</AbstractText>Comorbidities depending on hypokalemia or normokalemia were examined.</AbstractText>Of the 553 patients (61 +/- 13 yr, range 13-96), 56.1% had hypokalemic PA. The systolic (164 +/- 29 vs. 155 +/- 27 mm Hg; P < 0.01) and diastolic (96 +/- 18 vs. 93 +/- 15 mm Hg; P < 0.05) blood pressures were significantly higher in hypokalemic patients than in those with the normokalemic variant. The prevalence of cardiovascular events (angina pectoris, myocardial infarction, chronic cardiac insufficiency, coronary angioplasty) was 16.3%. Atrial fibrillation occurred in 7.1% and other atrial or ventricular arrhythmia in 5.2% of the patients. Angina pectoris and chronic cardiac insufficiency were significantly more prevalent in hypokalemic PA (9.0 vs. 2.1%, P < 0.001; 5.5 vs. 2.1%, P < 0.01). Overall, cerebrovascular comorbidities were not different between hypokalemic and normokalemic patients, however, stroke tended to be more prevalent in normokalemic patients.</AbstractText>Our data indicate a high prevalence of comorbidities in patients with PA. The hypokalemic variant is defined by a higher morbidity than the normokalemic variant regarding some cardiovascular but not cerebrovascular events. Thus, PA should be sought not only in hypokalemic but also in normokalemic hypertensives because high-excess morbidity occurs in both subgroups.</AbstractText> |
6,922 | Atrial fibrillation: pathogenesis, medical-surgical management and dental implications. | Atrial fibrillation (AF) is a cardiac rhythm disturbance arising from disorganized electrical activity in the atria, and it is accompanied by an irregular and often rapid ventricular response. It is the most common clinically significant dysrhythmia in the general and older population.</AbstractText>The authors conducted a MEDLINE search using the key terms "atrial fibrillation," "epidemiology," "pathophysiology," "treatment" and "dentistry." They selected contemporaneous articles published in peer-reviewed journals and gave preference to articles reporting randomized controlled trials.</AbstractText>The anticoagulant warfarin frequently is prescribed to prevent stroke caused by cardiogenic thromboemboli arising from stagnant blood in poorly contracting atria. Most dental procedures and a limited number of surgical procedures can be performed without altering warfarin dosage if the international normalized ratio value is within the therapeutic range of 2.0 to 3.0. Certain analgesic agents, antibiotic agents, antifungal agents and sedative hypnotics, however, should not be prescribed without consultation with the patient's physician because these medications may alter the patient's risk of hemorrhage and stroke.</AbstractText>AF affects nearly 2.5 million Americans, most of who are older than 60 years. Consultation with the patient's physician to discuss the planned dental treatment often is appropriate, especially for people who frequently have comorbid diseases such as coronary artery disease, congestive heart failure, diabetes and thyrotoxicosis, which are treated with multiple drug regimens.</AbstractText> |
6,923 | Isolated focus of ventricular fibrillation. | Mechanisms underlying the initiation of ventricular tachycardia have been described as either rapidly firing focus initiated by triggered activity or automaticity, or a reentrant wavefront initiated by a premature ventricular depolarization. Ventricular fibrillation can occur after ventricular tachycardia; however, uncertainty exists concerning its mechanism, whether it is caused by multiple wavelets, mother rotor, or a combination of both. This report describes the finding of a spontaneously isolated focus of ultrarapid ventricular activity recorded and ablated in a patient with nonischemic cardiomyopathy and ventricular tachycardia. |
6,924 | Heart failure enhances susceptibility to arrhythmogenic cardiac alternans. | Although heart failure (HF) is closely associated with susceptibility to sudden cardiac death (SCD), the mechanisms linking contractile dysfunction to cardiac electrical instability are poorly understood. Cardiac alternans has also been closely associated with SCD, and has been linked to a mechanism for amplifying electrical heterogeneities in the heart. However, previous studies have focused on alternans in normal rather than failing myocardium.</AbstractText>This study sought to investigate the hypothesis that HF enhances susceptibility to arrhythmogenic cardiac alternans.</AbstractText>High-resolution transmural optical mapping was performed in canine wedge preparations from normal (n = 8) and HF (n = 8) hearts produced by rapid ventricular pacing.</AbstractText>HF significantly (P < .004) lowered the heart rate (HR) threshold for action potential duration alternans (APD-ALT) from 236 +/- 25 beats/min to 185 +/- 25 beats/min. In dual optical mapping of action potentials and intracellular Ca experiments (n = 16), HF lowered the HR threshold for Ca-ALT (beat-to-beat alternations of cellular Ca cycling) from 238 +/- 35 to 177 +/- 26 beats/min (P < .005). Importantly: (1) Ca-ALT always either developed at slower HR or simultaneously with APD-ALT in the same cells, and (2) the magnitude of Ca-ALT and APD-ALT were closely correlated (P < .05). HF similarly lowered the HR threshold for Ca-ALT in isolated myocytes under nonalternating action potential clamp, indicating that HF enhances susceptibility to cellular alternans independent of HF-associated changes in repolarization. Importantly, HF significantly (P < .02) lowered the HR threshold for spatially discordant arrhythmogenic alternans (different regions of cells alternating in opposite phase, DIS-ALT). Ventricular fibrillation (VF) was induced in 88% of HF preparations, but only 12% of normal preparations (P < .003) and was uniformly preceded by development of DIS-ALT.</AbstractText>Heart failure increases the susceptibility to arrhythmogenic cardiac alternans, which arises from HF-induced impairment in calcium cycling.</AbstractText> |
6,925 | Gender differences and risk of ventricular tachycardia or ventricular fibrillation. | Healthy women have longer QT intervals and more drug-induced proarrhythmia compared to men, yet those given implantable cardioverter-difibrillators (ICDs) for ischemic cardiomyopathy have fewer episodes of ventricular tachycardia/ventricular fibrillation (VT/VF) than men. The role of repolarization duration and stability in arrhythmogenesis in men and women with structural heart disease has not been explored.</AbstractText>The purpose of this study was to analyze repolarization differences between men and women and their relation to the risk of VT/VF.</AbstractText>Multicenter Automatic Defibrillator Trial II study patients underwent 10-minute, resting digitized recordings at study entry. QT and heart rate were measured for each beat with a semiautomated method. QT variance was normalized for mean QT (QTVN) or for heart rate variance (QTVI). Spectral analysis of heart rate and QT time series was performed; coherence was indexed to quantify consistency of heart rate and QT power spectra. The incidence of VT/VF was determined by ICD interrogation.</AbstractText>There were 805 usable recordings (142 females); 463 received ICDs (86 females). There was no gender difference in mean or median QT, QTc, or heart rate. QTVN and QTVI were slightly (but significantly) higher, and the mean coherence was lower in women. In a Cox multivariate analysis, increased QTVN or QTVI (top quartile) was associated with a significantly higher risk for VT/VF in men (QTVN hazard ratio (HR) 2.2; confidence interval [CI] 1.4-3.4; P = .001; QTVI HR 1.9; CI 1.2-3.0; P = .006) but not in women, while reduced coherence (bottom quartile) predicted VT/VF in women (HR 3.3; CI 1.2-9.0; P = .021) but not in men.</AbstractText>In post-myocardial infarcation patients with depressed ejection fraction, both women and men manifest increased temporal variability in the QT interval. In men, QT variability by itself raised arrhythmic risk. In women, however, QT variability dissociated from HR variability (low coherence) appeared to be a uniquely significant predictor of arrhythmic events.</AbstractText> |
6,926 | Atrial fibrillation and heart failure. | Atrial fibrillation (AF) is the most common arrhythmia in congestive heart failure (HF) and indicates a worse prognosis. AF increases HF symptoms and increases in prevalence with increasing New York Heart Association class. AF also interferes with the ideal management of HF. Across all HF etiologies, AF may be a marker of disease severity. Yet, controversies exist regarding whether strategies to restore and maintain sinus rhythm can improve outcomes in HF. It is also unclear what the optimal strategy is to suppress the ventricular response to AF in patients with HF. As HF incidence and prevalence continue to rise, the authors sought to reinvestigate current literature that relates AF to HF and examine the impact of therapy on HF and/or AF. The authors performed a literature review using a MEDLINE search from 1966 to the present and included existing literature based on their strength of evidence. |
6,927 | A congenital form of junctional ectopic tachycardia. | Accessory pathways have been described as well as their Ecg identification criteria also in pediatric population. Radiofrequency ablation is a curative treatment but its application has been more limited in the paediatric population. The congenital form of junctional ectopic tachycardia was firstly described by Coumel et al. in 1976. It usually occurs in the first six months of life presenting as a persistent sustained form, lasting up to 90% of the time and it is hampered by high mortality. Its clinical presentation may be dramatic, being associated in up to 60% of cases with cardiomegaly and/or heart failure. Secondary dilated cardiomyopathy, ventricular fibrillation and sudden cardiac death have also been reported. We present a case of congenital form of junctional ectopic tachycardia in a 12-day-old newborn infant. Also this case is illustrative of the congenital form of junctional ectopic tachycardia. |
6,928 | Effect of timing and duration of a single chest compression pause on short-term survival following prolonged ventricular fibrillation. | Pauses during chest compressions are thought to have a detrimental effect on resuscitation outcome. The Guidelines 2005 have recently eliminated the post-defibrillation pause. Previous animal studies have shown that multiple pauses of increasing duration decrease resuscitation success. We investigated the effect of varying the characteristics of a single pause near defibrillation on resuscitation outcome.</AbstractText>Part A: 48 swine were anesthetized, fibrillated for 7min and randomized. Chest compressions were initiated for 90s followed by defibrillation and then resumption of chest compressions. Four groups were studied-G2000: 40s pause beginning 20s before, and ending 20s after defibrillation, A1: a 20s pause just before defibrillation, A2: a 20s pause ending 30s prior to defibrillation, and group A3: a 10s pause ending 30s prior to defibrillation. Part B: 12 swine (Group B) were studied with a protocol identical to Part A but with no pause in chest compressions. Primary endpoint was survival to 4h.</AbstractText>The survival rate was significantly higher for groups A1, A2, A3, and B (5/12, 7/12, 5/12, and 5/12 survived) than for the G2000 group (0/12, p<0.05). Survival did not differ significantly among groups A1, A2, A3, and B.</AbstractText>These results suggest that the Guidelines 2005 recommendation to omit the post-shock pulse check and immediately resume chest compressions may be an important resuscitation protocol change. However, these results also suggest that clinical maneuvers further altering a single pre-shock chest compression pause provide no additional benefit.</AbstractText> |
6,929 | Clinical and genetic analysis of long QT syndrome in children from six families in Saudi Arabia: are they different? | Congenital long QT syndrome (LQTS) is an inherited cardiac arrhythmia disorder characterized by prolongation of the QT interval; patients are predisposed to ventricular tachyarrhythmias and fibrillation leading to recurrent syncope or sudden cardiac death. We performed clinical and genetic studies in six Saudi Arabian families with a history of sudden unexplained death of children. Clinical symptoms, ECG phenotypes, and genetic findings led to the diagnosis of LQT1 in two families (recessive) and LQT2 in four families (three recessive and one dominant). Onset of arrhythmia was more severe in the recessive carriers and occurred during early childhood in all recessive LQT1 patients. Arrhythmia originated at the intrauterine stages of life in the recessive LQT2 patients. LQT1, causing mutation c.387-5 T > A in the KCNQ1 gene, and LQT2, causing mutation c.3208 C > T in the KCNH2 gene, are presumably founder mutations in the Assir province of Saudi Arabia. Further, all LQTS causing mutations detected in this study are novel and have not been reported in other populations. |
6,930 | Atrial arrhythmogenesis in wild-type and Scn5a+/delta murine hearts modelling LQT3 syndrome. | Long QT(3) (LQT3) syndrome is associated with abnormal repolarisation kinetics, prolonged action potential durations (APD) and QT intervals and may lead to life-threatening ventricular arrhythmias. However, there have been few physiological studies of its effects on atrial electrophysiology. Programmed electrical stimulation and burst pacing induced atrial arrhythmic episodes in 16 out of 16 (16/16) wild-type (WT) and 7/16 genetically modified Scn5a+/Delta (KPQ) Langendorff-perfused murine hearts modelling LQT3 (P < 0.001 for both), and in 14/16 WT and 1/16 KPQ hearts (P < 0.001 for both; Fisher's exact test), respectively. The arrhythmogenic WT hearts had significantly larger positive critical intervals (CI), given by the difference between atrial effective refractory periods (AERPs) and action potential durations at 90% recovery (APD(90)), compared to KPQ hearts (8.1 and 3.2 ms, respectively, P < 0.001). Flecainide prevented atrial arrhythmias in all arrhythmogenic WT (P < 0.001) and KPQ hearts (P < 0.05). It prolonged the AERP to a larger extent than it did the APD(90) in both WT and KPQ groups, giving negative CIs. Quinidine similarly exerted anti-arrhythmic effects, prolonged AERP over corresponding APD(90) in both WT and KPQ groups. These findings, thus, demonstrate, for the first time, inhibitory effects of the KPQ mutation on atrial arrhythmogenesis and its modification by flecainide and quinidine. They attribute these findings to differences in the CI between WT and mutant hearts, in the presence or absence of these drugs. Thus, prolongation of APD(90) over AERP gave positive CI values and increased atrial arrhythmogenicity whereas lengthening of AERP over APD(90) reduced such CI values and produced the opposite effect. |
6,931 | Management of atrial fibrillation in the elderly. | Atrial fibrillation (AF) is associated with a higher incidence of mortality, stroke, and coronary events than is sinus rhythm. AF with a rapid ventricular rate may cause a tachycardia-related cardiomyopathy. Immediate direct-current (DC) cardioversion should be performed in patients with AF and acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta blockers, diltiazem, or verapamil may be administered to slow immediately a very rapid ventricular rate in AF. An oral beta blocker, verapamil, or diltiazem should be used in persons with AF if a fast ventricular rate occurs at rest or during exercise despite digoxin. Amiodarone may be used in selected patients with symptomatic life-threatening AF refractory to other drugs. Digoxin should not be used to treat patients with paroxysmal AF. Nondrug therapies should be performed in patients with symptomatic AF in whom a rapid ventricular rate cannot be slowed by drugs. Paroxysmal AF associated with the tachycardia-bradycardia syndrome should be treated with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in patients with AF and symptoms such as dizziness or syncope associated with ventricular pauses greater than 3 seconds which are not drug-induced. Elective DC cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than does medical cardioversion in converting AF to sinus rhythm. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective DC or drug cardioversion of AF and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer, especially in older patients, ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiar-rhythmic 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 325 mg daily. |
6,932 | Provocation of silence. | We describe the development of a Brugada ECG together with sinus- and ventricular arrest after intravenous flecainide for atrial fibrillation in a patient in whom eventually a SCN5a mutation was identified. Unrecognized SCN5A mutations could underlie class IC-induced sinus arrest and conduction defects in some patients. |
6,933 | Presence Of Left Atrial Appendage Thrombus In Patients Presenting For Left Atrial Ablation Of Atrial Fibrillation Despite Pre-Operative Anticoagulation. | <b>Background:</b> One of the recognised complications of left atrial ablation for atrial fibrillation (AF) is stroke. Left atrial (LA) thrombus, which may be dislodged by catheter manipulation, is an absolute contraindication to ablation. It is unclear whether imaging of the left atrial appendage (LAA) by transesophageal echo (TEE) is mandatory to exclude LA clot prior to ablation, particularly in "low-risk" patients with paroxysmal AF and normal left ventricular (LV) function. <b>Methods and Results:</b> We carried out a retrospective analysis of pre-ablation TEE in patients presenting for ablation of AF. Images from 244 ablation procedures carried out in 148 patients were examined, including 106 patients with paroxysmal AF and normal LV function. Despite at least 4 weeks of pre-operative therapeutic anticoagulation with Warfarin (INR>2.0), LAA thrombus was identified in 4 patients (2.7% (0.1-5.3%)). These included 2 patients with paroxysmal AF and normal LV function, although both had a high arrhythmia burden. The thrombi regressed with intensification of anticoagulation. <b>Conclusions:</b> Pre-operative imaging of the LAA remains advisable to exclude thrombus prior to ablation for AF even in patients with paroxysmal AF and normal LV function, especially if there is a high AF burden. |
6,934 | Atrial Fibrillation And Coronary Heart Disease:Fatal Attraction. | In this manuscript, the profile and clinical management of hypertensive patients with chronic ischemic heart disease and atrial fibrillation (AF) is examined and whether high heart rate is associated with a different profile is determined. CINHTIA was a cross-sectional and multicenter survey aimed to define the clinical profile of hypertensive patients with chronic ischemic heart disease daily attended in Spain. Blood pressure, LDL-cholesterol and diabetes control rates were established according to ESHESC 2003, NCEP-ATP III and ADA 2005 guidelines, respectively. Out of the 2024 patients, 338 (16.7%) exhibited AF. The group of patients with AF was older and with higher prevalence of diabetes, organ damage and cardiovascular disease. Blood pressure (41.8% vs 34.5%, p=0.014) and diabetes (28.5% vs 20.9%,p=0.044) were worse controlled in patients with AF, with a trend to a lower control of LDL-cholesterol (31.2% vs 26.8%, p=0.093). When distributing patients with AF according to heart rate, except for smoking, left ventricular hypertrophy and peripheral arterial disease that were more frequent in those with higher heart rate, no significant differences were found in other risk factors or organ damage between groups. Blood pressure, glycemia and LDL-cholesterol were worse controlled in the subgroup with highest heart rate. In clinical practice, hypertensive patients with chronic ischemic heart disease and AF have a bad prognosis not only due to a worse clinical profile, but also due to lower risk factors control rates. In contrast with patients at sinus rhythm, higher heart rate was less related with a worse clinical profile in subjects with AF. |
6,935 | QT Prolongation Following Ectopic Beats: Initial Data Regarding The Upper Limit Of Normal With Possible Implications For Antiarrhythmic Therapy And Concealed (Unexpressed) Long QT. | Background:</b> Ectopic beats are frequently associated with morphologic repolarization alterations of ensuing sinus beats. Less is known about repolarization duration alterations of post-ectopic sinus beats. In one patient who developed long QT and torsades de pointes upon exposure to a class III antiarrhythmic drug, and was later genotyped as being a carrier for long QT syndrome (LQTS) type 1, review of a pre-drug Holter monitor study revealed marked QT prolongation of post-ectopic sinus beats. In wondering whether this might be a common clue to "concealed" unexpressed LQTS, we realized that we must first characterize the range of post-ectopic QT prolongation present in normals. Prolongation beyond the upper limit of this range might then raise suspicion of possible LQTS and alter the antiarrhythmic drug selection process for the suppression of atrial fibrillation or other arrhythmias. Methods:</b> Accordingly, we assessed the presence/degree of repolarization prolongation following premature ectopic impulses in 166 subjects with normal conduction intervals and normal repolarization on their resting 12-lead ECG, 75 of whom had no known associated cardiovascular disorder of any kind. That is, in our subjects, the maximal prolongation of the QT interval of the sinus beat following isolated ventricular and atrial premature complexes was characterized. Results:</b> QT prolongation is common in post ectopic sinus beats. However, in our subjects the uncorrected QT interval of post-ectopic sinus beats never exceeded 480 ms in duration [which was much shorter than that seen (510-590 ms) in our gene carrier].</AbstractText>The QT interval in normal subjects may prolong following premature complexes but not to a value in excess of 480 ms.</AbstractText> |
6,936 | Hepatotoxicity after intravenous amiodarone. | Amiodarone is a class III antiarrhythmic agent with a long half-life which is used to control atrial and ventricular arrhythmias, including atrial flutter and fibrillation. We describe here the case of an elderly woman (77 years of age) who was hospitalized for acute atrial fibrillation, abdominal pain, and dyspnea. In the Emergency Department, treatment with intravenous amiodarone was begun. The following day, the patient developed acute liver damage; improved liver function occurred following the withdrawal of amiodarone. Complete recovery of liver function was documented after three weeks. Unfortunately, the patient died from a severe infectious disease, with multiple organ failure. |
6,937 | Spontaneous and simultaneous multivessel coronary spasm causing multisite myocardial infarction, cardiogenic shock, atrioventricular block, and ventricular fibrillation. | A 57-year-old Taiwanese man with a past history of variant angina developed simultaneous anterior and inferior myocardial infarction, atrioventricular block, cardiogenic shock, and eventually ventricular fibrillation. Left coronary angiography revealed simultaneous occlusion of the left anterior descending and the left circumflex coronary arteries, which was relieved by intracoronary administration of isosorbide dinitrate. This is the first report of such a case in the English-language medical literature. |
6,938 | Tricuspid regurgitation in mitral valve disease incidence, prognostic implications, mechanism, and management. | Tricuspid regurgitation (TR) in patients with mitral valve (MV) disease is associated with poor outcome and predicts poor survival, heart failure, and reduced functional capacity. It is common if left untreated after MV replacement mainly in rheumatic patients, but it is also common in patients with ischemic mitral regurgitation. It is less common, however, in those with degenerative mitral regurgitation. It might appear many years after surgery and might not resolve after correcting the MV lesion. Late TR might be caused by prosthetic valve dysfunction, left heart disease, right ventricular (RV) dysfunction and dilation, persistent pulmonary hypertension, chronic atrial fibrillation, or by organic (mainly rheumatic) tricuspid valve disease. Most commonly, late TR is functional and isolated, secondary to tricuspid annular dilation. Outcome of isolated tricuspid valve surgery is poor, because RV dysfunction has already occurred at that point in many patients. MV surgery or balloon valvotomy should be performed before RV dysfunction, severe TR, or advanced heart failure has occurred. Tricuspid annuloplasty with a ring should be performed at the initial MV surgery, and the tricuspid annulus diameter (>or=3.5 cm) is the best criterion for performing the annuloplasty. In this article we will review the current data available for understanding the prognostic implications, mechanism, and management of TR in patients with MV disease. |
6,939 | Cardiac surgery in patients with haemophilia. | Today the populations of haemophilia patients in many countries have a higher life expectancy than previously known, and age-related disorders such as arterial disease are expected to become more prevalent, calling for surgical intervention. Cardiac surgery constitutes a major haemostatic challenge because of sternotomy, the need of total heparinization, extracorporal circulation, mild hypothermia and cardiac arrest. To evaluate our current experience and results with cardiac surgery in patients with haemophilia the present case series report on six patients with haemophilia A (Severe = 1, Moderate = 1, Mild = 4) undergoing cardiac surgery (coronary artery bypass grafting; CABG = 2, aortic valve replacement = 1, CABG + aortic valve replacement = 2, ventricular resection + mitral valve reconstruction = 1). The present paper provides detailed information on the haemostatic treatment regimens adopted (factor concentrate dosages, timing and duration) and postoperative thromboprophylaxis (dosing and duration of low molecular weight heparin). Moreover, we present data on concomitant disorders (hypertension, hypercholesterolaemia, atrial fibrillation and diabetes), left ventricle ejection fraction (30-60%), type of anaesthesia, total amount of heparin (34 500-53 500 IU) and duration of extracorporeal circulation (80-115 min). Clinical outcomes included: re-operation because of bleeding (none), transfusion requirements, peri- and postoperative blood loss and complications and postoperative development of inhibitors (none). Clinical outcomes were compared with a control group of patients (n = 5993) without haemophilia and we found no difference in postoperative morbidity. Adopting meticulously supervised haemostatic treatment regimens, we have successfully performed major cardiac surgery in patients with haemophilia A. The clinical outcome as well as the severity and incidence of postoperative complications were similar to patients without haemophilia. |
6,940 | Relationship of reverse anatomical remodeling and ventricular arrhythmias after cardiac resynchronization. | Cardiac resynchronization (CRT) affects reverse anatomical remodeling in patients with heart failure. CRT has also been associated with fewer ventricular arrhythmias and reduced sudden death in some clinical trials, but the predictors and mechanism of the antiarrhythmic actions of CRT have not been well defined. The purpose of this study is to investigate the relationship of reverse anatomical remodeling to ventricular arrhythmias in CRT patients.</AbstractText>A retrospective analysis was performed of the InSync III Marquis study, a prospective, randomized, multicenter CRT trial. Echocardiographic data from 198 patients were obtained at baseline and after 6 months of CRT, and anatomical responders were defined as a reduction in left ventricular end systolic volume (LVESV) of >or=15%. Anatomical responders (n = 71, 36%) demonstrated 29% fewer single premature ventricular contractions beats (PVCs) (P = 0.0001), 48% fewer PVC runs (p = 0.0096), and fewer treated episodes of ventricular tachycardia or fibrillation (VT/VF) (P = 0.050) than nonresponders. Multiple regression analysis demonstrated that responder status significantly predicted single PVCs and PVC runs. Gender was the most important predictor of treated VT/VF with females having no episodes over 6 months of follow-up.</AbstractText>Anatomic responders to CRT demonstrate significantly fewer single PVCs and runs of PVCs. The implication of these observations is that anatomic remodeling is linked to electrical remodeling.</AbstractText> |
6,941 | A comparison of chronaxies for ventricular fibrillation induction, defibrillation, and cardiac stimulation: unexpected findings and their implications. | A low-energy (<or= 4 J) cardioversion shock (LEC) either terminates reentrant ventricular tachycardia (VT) or accelerates it to ventricular fibrillation (VF). Optimization of the duration and amplitude of LEC shocks could improve the success rate of VT termination without VF induction.</AbstractText>In order to learn how LEC shocks may be optimized, we used an animal model to compare the strength-duration curve for VF induction and the strength-duration curve for cardiac stimulation via the shock coil. Conventional implantable cardioverter-defibrillator (ICD) leads were implanted in 12 narcotized pigs from 20 kg to 25 kg in weight. Stimulation, VF induction, and defibrillation pulses were delivered by custom-designed stimulators at preset pulse durations and amplitudes. The corresponding hyperbolic strength-duration curves were constructed using the least-squares fit method and averaged for all the animals. The mean chronaxie for stimulation via the shock coil of 0.23 ms was significantly shorter than both defibrillation (4.8 ms) and VF induction (3.1 ms) chronaxie values. At a shock duration of 0.3 ms or less, the mean VF-induction threshold amplitude exceeded 300 V.</AbstractText>It may be reasonable to study whether LEC pulses from 0.25 ms to 0.30 ms in duration and up to 250 V in amplitude would increase therapeutic yield in VT termination without VF induction in humans. Contrary to the current belief, the discrepancy between defibrillation and stimulation chronaxie is not caused by different electrode size. We postulate that the time constant of the fast sodium channel reactivation may be the underlying reason.</AbstractText> |
6,942 | Toxicity in Doberman Pinchers with ventricular arrhythmias treated with amiodarone (1996-2005). | Asymptomatic Doberman Pinschers with dilated cardiomyopathy (DCM) often die suddenly owing to ventricular tachycardia that degenerates into ventricular fibrillation. A safe and effective antiarrhythmic drug treatment is needed. This will require a large, well-controlled, prospective study.</AbstractText>Amiodarone toxicity is common in Dobermans with occult DCM and ventricular tachyarrhythmias refractory to antiarrhythmia therapy. Infrequent monitoring of hepatic function is inadequate. Frequent monitoring may be useful to determine dogs in which the dosage should be decreased or the drug withdrawn.</AbstractText>Medical records from the University of Georgia and Cornell University were searched for Doberman Pinschers diagnosed with preclinical DCM that received amiodarone for severe ventricular arrhythmias refractory to other antiarrhythmic agents. Echocardiographic data, Holter recording data, hepatic enzyme serum activity, and serum amiodarone concentrations were recorded. The presence of clinical signs of toxicity was recorded. Serum amiodarone concentrations were obtained in some dogs.</AbstractText>Reversible toxicity was identified in 10 of 22 (45%) dogs.</AbstractText>Adverse effects from amiodarone were common and were, in part, dosage related. Patients should be monitored for signs of toxicity and liver enzyme activity should be measured at least monthly.</AbstractText> |
6,943 | [Development of three-dimensional analysis of current density distribution by 64-ch magentocardiography and clinical application]. | Magnetocardiography (MCG) using a SQUID sensor is characterized by three dimensional cardiac electrical phenomena from magnetic fields, because it is hard to be affected by organ constitution of lungs and torso configuration. We have developed three-dimensional (3D) electric current density distribution analysis by a spatial filter method. At this symposium, we report clinical utility of 64-channel (64-ch) MCG. Subjects consisted of 20 normal volunteers, 10 cases with old myocardial infarction, 13 cases with atrial fibrillation (AFIB) who received surgical pulmonary (PV) isolation, and representative case with fetus premature ventricular complex (PVC). We recorded 10-min MCG data of magnetic field composition (a Bz ingredient) which was perpendicular to body surface in a magnetism shield, using 64-ch SQUID sensors (17.5 x 17.5 cm) built-in in MCG instrumentation(sampling; 500ms, total frequency characteristic; 0.1-200 Hz). We conducted 3D heart outline from electric current density calculated by magnetic field distribution. We also generated 3D functional images of the RT (activation recovery time) dispersion and spatial spectral distribution of a fibrillation wave. Increased fluctuation on RT dispersion map corresponded with space location of myocardial infarction. The mean frequency of 3D spectral map in persistent AFIB showed a higher value than that with restored a sinus rhythm (7.7 +/- 0.5 Hz vs. 6.5 +/- 0.7 Hz). We also demonstrated a fetus PVC. We concluded that 64-ch MCG can evaluate 3D spatial location of myocardial injury, 3D spectral map and characteristic frequency, and fetus arrhythmia. In future, further technical development in the fields of MCG measurement would be necessary for avoiding the used of unshielded room or liquid He. |
6,944 | Continuous improvements in "chain of survival" increased survival after out-of-hospital cardiac arrests: a large-scale population-based study. | The impact of ongoing efforts to improve the "chain of survival" for out-of-hospital cardiac arrest (OHCA) is unclear. The objective of this study was to evaluate the incremental effect of changes in prehospital emergency care on survival after OHCA.</AbstractText>This prospective, population-based observational study involved consecutive patients with OHCA from May 1998 through December 2006. The primary outcome measure was 1-month survival with favorable neurological outcome. Multiple logistic regression analysis was used to assess factors that were potentially associated with better neurological outcome. Among 42,873 resuscitation-attempted adult OHCAs, 8782 bystander-witnessed arrests of presumed cardiac origin were analyzed. The median time interval from collapse to call for medical help, first cardiopulmonary resuscitation, and first shock shortened from 4 (interquartile range [IQR] 2 to 11) to 2 (IQR 1 to 5) minutes, from 9 (IQR 5 to 13) to 7 (IQR 3 to 11) minutes, and from 19 (IQR 13 to 22) to 9 (IQR 7 to 12) minutes, respectively. Neurologically intact 1-month survival after witnessed ventricular fibrillation increased from 6% (6/96) to 16% (49/297; P<0.001). Among all witnessed OHCAs, earlier cardiopulmonary resuscitation (odds ratio per minute 0.89, 95% confidence interval 0.85 to 0.93) and earlier intubation (odds ratio per minute 0.96, 95% confidence interval 0.94 to 0.99) were associated with better neurological outcome. For ventricular fibrillation, only earlier shock was associated with better outcome (odds ratio 0.84, 95% confidence interval 0.80 to 0.88).</AbstractText>Data from a large, population-based cohort demonstrate a continuous increase in OHCA survival with improvement in the chain of survival. The incremental benefit of early advanced care on OHCA survival is also suggested.</AbstractText> |
6,945 | Atrial fibrillation associated with chocolate intake abuse and chronic salbutamol inhalation abuse. | The use of substances as the substrate for atrial fibrillation is not frequently recognized. Chocolate is derived from the roasted seeds of the plant theobroma cacao and its components are the methylxanthine alkaloids theobromine and caffeine. Caffeine is a methylxanthine whose primary biological effect is the competitive antagonism of the adenosine receptor. Normal consumption of caffeine was not associated with risk of atrial fibrillation or flutter. Sympathomimetic effects, due to circulating catecholamines cause the cardiac manifestations of caffeine overdose toxicity, produce tachyarrhythmias such as supraventricular tachycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.The commonly used doses of inhaled or nebulized salbutamol induced no acute myocardial ischaemia, arrhythmias or changes in heart rate variability in patients with coronary artery disease and clinically stable asthma or chronic obstructive pulmonary disease. Two-week salbutamol treatment shifts the cardiovascular autonomic regulation to a new level characterized by greater sympathetic responsiveness and slight beta2-receptor tolerance. We present a case of atrial fibrillation associated with chocolate intake abuse in a 19-year-old Italian woman with chronic salbutamol inhalation abuse. This case focuses attention on chocolate intake abuse associated with chronic salbutamol abuse as the substrate for atrial fibrillation. |
6,946 | The effects of trimetazidine on p-wave duration and dispersion in heart failure patients. | P-wave duration and dispersion (PWD) have been shown to be noninvasive predictors for development of atrial fibrillation. Thus, it may be possible to attenuate atrial fibrillation risk through normalization of P-wave duration and dispersion. Trimetazidine, a metabolic modulator, has been reported to improve cardiac function in heart failure (HF) patients.</AbstractText>Thirty-six HF patients being treated with angiotensin inhibitors, carvedilol, spironolactone, and furosemide were prescribed trimetazidine, 20 mg three times a day. Electrocardiographic and echocardiographic examinations were obtained before and 6 months after addition of trimetazidine in HF patients and 36 healthy control group patients having normal echocardiographic examination.</AbstractText>Maximum P-wave duration (Pmax) (106.7 +/- 15.8 vs. 91.7 +/- 12.7 ms) and PWD (57.2 +/- 15.4 vs. 37.9 +/- 16.7 ms) were significantly longer in HF patients compared to the control group. There were significant correlations of Pmax and PWD with left atrial diameter (r = 0.508, P = < 0.001 and r = 0.315, P = 0.029), left ventricular ejection fraction (LVEF) (r = 0.401, p = 0.005 and r = 0.396, P = 0.005), deceleration time (r = 0.296, P = 0.032 and r = 0.312, P = 0.035), and isovolumetric relaxation time (r = 0.265, P = 0.038 and r = 0.322, P = 0.015). There were significant improvements in LVEF (32.7 +/- 6.5% to 37.2 +/- 5.5%, P = 0.036), left atrial diameter (41.5 +/- 6.7 to 40.3 +/- 6.1 mm, P < 0.001), and Pmax (106.7 +/- 15.8 to 102.2 +/- 11.5 ms, P = 0.006) and PWD (57.2 +/- 15.4 to 48.9 +/- 10.1 ms, P < 0.001) during follow-up.</AbstractText>Trimetazidine added to optimal medical therapy in HF may improve Pmax and PWD in association with improved left ventricular function. Longer-term and larger studies are necessary to evaluate whether these findings may have clinical implications on prevention of atrial fibrillation.</AbstractText> |
6,947 | New or aggravated heart failure during long-term right ventricular pacing after AV junctional catheter ablation. | Atrioventricular junctional ablation (AVJA) improves symptoms and quality of life in patients with pharmacologically resistant atrial fibrillation (AF). However, long-term right ventricular stimulation has also been reported to lead to deterioration of the left ventricular function. We retrospectively analyzed the incidence of new or aggravated heart failure (HF) during long-term right ventricular stimulation following AVJA.</AbstractText>Two hundred thirteen patients (110F:103M), 73 +/- 10 years old, were followed for a period of 6 +/- 3 years after AVJA. Forty-nine patients (23%) were known to have HF before AVJA. New HF was diagnosed if at least two of the following criteria were present: NYHA class >2, an LVEF <45%, and medication for HF. Aggravated HF was defined as an increase in the functional class and/or new prescription of medication for HF. All-cause death was a secondary endpoint.</AbstractText>During follow-up, 26% of the patients with known HF showed an aggravation of HF, while 13% developed new symptoms of HF. High age and low EF were independent predictors of new or aggravated HF and of new HF, while none of the tested variables predicted aggravation of known HF. The all-cause mortality was 16%, where high age and coronary artery disease were found to be independent predictors.</AbstractText>AVJA followed by right ventricular pacing was associated with aggravated HF in 23% of patients with known HF, while development of new symptoms of HF occurred much less often during follow-up (13%). The majority of patients who underwent AVJA continued to do well during long-term follow-up.</AbstractText> |
6,948 | Organization of ventricular fibrillation in the human heart: experiments and models. | Sudden cardiac death is a major health problem in the industrialized world. The lethal event is typically ventricular fibrillation (VF), during which the co-ordinated regular contraction of the heart is overthrown by a state of mechanical and electrical anarchy. Understanding the excitation patterns that sustain VF is important in order to identify potential therapeutic targets. In this paper, we studied the organization of human VF by combining clinical recordings of electrical excitation patterns on the epicardial surface during in vivo human VF with simulations of VF in an anatomically and electrophysiologically detailed computational model of the human ventricles. We find both in the computational studies and in the clinical recordings that epicardial surface excitation patterns during VF contain around six rotors. Based on results from the simulated three-dimensional excitation patterns during VF, which show that the total number of electrical sources is 1.4 +/- 0.12 times greater than the number of epicardial rotors, we estimate that the total number of sources present during clinically recorded VF is 9.0 +/- 2.6. This number is approximately fivefold fewer compared with that observed during VF in dog and pig hearts, which are of comparable size to human hearts. We explain this difference by considering differences in action potential duration dynamics across these species. The simpler spatial organization of human VF has important implications for treatment and prevention of this dangerous arrhythmia. Moreover, our findings underline the need for integrated research, in which human-based clinical and computational studies complement animal research. |
6,949 | Ventricular electrophysiology in congestive heart failure and its correlation with heart rate variability and baroreflex sensitivity: a canine model study. | This study investigated ventricular electrophysiological characteristics and the correlation between these parameters and heart rate variability (HRV) and baroreflex sensitivity (BRS) in a canine congestive heart failure (CHF) model.</AbstractText>Haemodynamics, HRV, BRS, and ventricular electrophysiological variables were measured 4-5 weeks after sham operation (control dogs) and pacemaker implantation, and rapid right ventricular pacing at 240 bpm (CHF group). In the CHF group, significant differences from the control group in ventricular effective refractory period (VERP), monophasic action potential (MAP) duration (MAPD(90)), ventricular late repolarization duration (VLRD), the ratio of VERP to MAPD(90), dispersion of ventricular recovery time (VRT-D), and ventricular fibrillation threshold (VFT) were noted. Both BRS and the time and power domain parameters of HRV were significantly decreased in the CHF group compared with the control group, and a significant, positive correlation between HRV and BRS was identified in the CHF group. Heart rate variability and BRS were negatively and significantly correlated with VLRD and VRT-D, and were positively correlated with VERP/MAPD(90) and VFT in the CHF group.</AbstractText>These results suggest that ventricular electrophysiological characteristics correlated with abnormal autonomic nerve function may have important effects on sudden cardiac death. Further research is warranted.</AbstractText> |
6,950 | Modified alternating current defibrillation: a new defibrillation technique. | Defibrillation is the only clinically effective treatment for ventricular fibrillation (VF). Early defibrillation improves the outcome and increases the chance of survival with full recovery. Immediate availability of a home-based defibrillator using mains-derived alternating current (AC) current will drastically improve the outcome. The aim was to develop a defibrillator based on the modulated AC, resembling biphasic configuration, and compare its efficacy, in a pig model, with a standard direct current (DC) defibrillator.</AbstractText>A computer controlled, modulated AC defibrillation system was developed using a high-voltage switch and a high-voltage transformer. The efficacy and safety was evaluated in five pigs (30-40 kg), under general anaesthesia with ketamine and isoflouran. A single quadripolar-pacing catheter was inserted percutaneously. Ventricular fibrillation was induced with rapid ventricular burst pacing, and stable VF was defibrillated after 15 s. Defibrillation threshold (DFT) was determined in each animal with AC and standard DC shock using the step-down protocol. A biphasic-like shock was used with a short isoelectric stage between the phases. The DFT with AC was 70.83 +/- 24.81 J and with DC was 65.83 +/- 12.41 J (P = 0.49). No macroscopic damage was observed after AC or DC defibrillation.</AbstractText>Modulated AC defibrillation is safe and effective as the commercially available DC defibrillation. The defibrillator is built from an inexpensive high-voltage transformer, without the need for capacitor, batteries, or routine maintenance, delivers repeated shock without any delay, and provides pacing as well. It may be an ideal platform for automatic home defibrillator.</AbstractText> |
6,951 | Evidence regarding clinical use of microvolt T-wave alternans. | Microvolt T-wave alternans (MTWA) testing in many studies has proven to be a highly accurate predictor of ventricular tachyarrhythmic events (VTEs) in patients with risk factors for sudden cardiac death (SCD) but without a prior history of sustained VTEs (primary prevention patients). In some recent studies involving primary prevention patients with prophylactically implanted cardioverter-defibrillators (ICDs), MTWA has not performed as well.</AbstractText>This study examined the hypothesis that MTWA is an accurate predictor of VTEs in primary prevention patients without implanted ICDs, but not of appropriate ICD therapy in such patients with implanted ICDs.</AbstractText>This study identified prospective clinical trials evaluating MTWA measured using the spectral analytic method in primary prevention populations and analyzed studies in which: (1) few patients had implanted ICDs and as a result none or a small fraction (< or =15%) of the reported end point VTEs were appropriate ICD therapies (low ICD group), or (2) many of the patients had implanted ICDs and the majority of the reported end point VTEs were appropriate ICD therapies (high ICD group).</AbstractText>In the low ICD group comprising 3,682 patients, the hazard ratio associated with a nonnegative versus negative MTWA test was 13.6 (95% confidence interval [CI] 8.5 to 30.4) and the annual event rate among the MTWA-negative patients was 0.3% (95% CI: 0.1% to 0.5%). In contrast, in the high ICD group comprising 2,234 patients, the hazard ratio was only 1.6 (95% CI: 1.2 to 2.1) and the annual event rate among the MTWA-negative patients was elevated to 5.4% (95% CI: 4.1% to 6.7%). In support of these findings, we analyzed published data from the Multicenter Automatic Defibrillator Trial II (MADIT II) and Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) trials and determined that in those trials only 32% of patients who received appropriate ICD therapy averted an SCD.</AbstractText>This study found that MTWA testing using the spectral analytic method provides an accurate means of predicting VTEs in primary prevention patients without implanted ICDs; in particular, the event rate is very low among such patients with a negative MTWA test. In prospective trials of ICD therapy, the number of patients receiving appropriate ICD therapy greatly exceeds the number of patients who avert SCD as a result of ICD therapy. In trials involving patients with implanted ICDs, these excess appropriate ICD therapies seem to distribute randomly between MTWA-negative and MTWA-nonnegative patients, obscuring the predictive accuracy of MTWA for SCD. Appropriate ICD therapy is an unreliable surrogate end point for SCD.</AbstractText> |
6,952 | Plesiomonas shigelloides pneumonia. | Plesiomonas shigelloides is known to cause mild to cholera-like diarrhea in most infected persons. In immunocompromised patients extra-intestinal manifestations have been described. We report the first case of pneumonia caused by P. shigelloides in a 76-year-old woman who had undergone a curative gastrectomy and esophageal-jejunostomy due to a low differentiated adenocarcinoma of the stomach (pT2, pN1 pMx, G3, R0, Lauren: intestinal type). The patient was admitted in hospital with clinical signs of pulmonary infection. CT-scan revealed a cavernous lesion in the right upper pulmonary lobe. Bronchial lavage showed a granulocytic inflammation 105CFU/ml P. shigelloides. Although antibiotic treatment led to a decrease of inflammation parameters and decrease of the pulmonary infiltrate the patient died due to development of torsades de pointes tachycardia leading to ventricular fibrillation and hypoxic brain damage. |
6,953 | Effect of transport interval on out-of-hospital cardiac arrest survival in the OPALS study: implications for triaging patients to specialized cardiac arrest centers. | To identify any association between out-of-hospital transport interval and survival to hospital discharge in victims of out-of-hospital cardiac arrest.</AbstractText>Data from the Ontario Prehospital Advanced Life Support Study (January 1, 1991, to December 31, 2002), an Utstein-compliant registry of out-of-hospital cardiac arrest patients from 21 communities, were analyzed. Logistic regression identified factors that were independently associated with survival in consecutive adult, nontraumatic, out-of-hospital cardiac arrest patients and in the subgroup with return of spontaneous circulation.</AbstractText>A total of 18,987 patients met criteria and 15,559 (81.9%) had complete data for analysis (study group). Return of spontaneous circulation was achieved in 2,299 patients (14.8%), and 689 (4.4%) survived to hospital discharge. Median transport interval was 4.0 minutes (25th quartile 3.0 minutes; 75th quartile 6.2 minutes) for survivors and 4.2 minutes (25th quartile 3.0, 75th quartile 6.2) for nonsurvivors. Logistic regression revealed multiple factors that were independently associated with survival: witnessed arrest (odds ratio 2.61; 95% confidence interval [CI] 2.05 to 3.34), bystander cardiopulmonary resuscitation (odds ratio 2.22; 95% CI 1.82 to 2.70), initial rhythm of ventricular fibrillation/tachycardia (odds ratio 2.22; 95% CI 1.97 to 2.50), and shorter emergency medical services (EMS) response interval (odds ratio 1.26; 95% CI 1.20 to 1.33). There was no association between transport interval and survival in either the study group (odds ratio 1.01; 95% CI 0.99 to 1.05) or the return of spontaneous circulation subgroup (odds ratio 1.04; 95% CI 0.99, 1.08).</AbstractText>In a large out-of-hospital cardiac arrest study from demographically diverse EMS systems, longer transport interval was not associated with decreased survival. Given the growing evidence showing major influence from specialized postarrest care, these findings support conducting clinical trials that assess the effectiveness and safety of bypassing local hospitals to take patients to regional cardiac arrest centers.</AbstractText> |
6,954 | Automated external defibrillators and simulated in-hospital cardiac arrests. | To test the hypothesis that pediatric residents would have shorter time to attempted defibrillation using automated external defibrillators (AEDs) compared with manual defibrillators (MDs).</AbstractText>A prospective, randomized, controlled trial of AEDs versus MDs was performed. Pediatric residents responded to a simulated in-hospital ventricular fibrillation cardiac arrest and were randomized to using either an AED or MD. The primary end point was time to attempted defibrillation.</AbstractText>Sixty residents, 21 (35%) interns, were randomized to 2 groups (AED = 30, MD = 30). Residents randomized to the AED group had a significantly shorter time to attempted defibrillation [median, 60 seconds (interquartile range, 53 to 71 seconds)] compared with those randomized to the MD group [median, 103 seconds (interquartile range, 68 to 288 seconds)] (P < .001). All residents in the AED group attempted defibrillation at <5 minutes compared with 23 (77%) in the MD group (P = .01).</AbstractText>AEDs improve the time to attempted defibrillation by pediatric residents in simulated cardiac arrests. Further studies are needed to help determine the role of AEDs in pediatric in-hospital cardiac arrests.</AbstractText> |
6,955 | Druggable targets for sudden cardiac death prevention: lessons from the past and strategies for the future. | Sudden cardiac death (SCD) is most commonly caused by ventricular fibrillation (VF). The single largest cohort of victims is the population with little or no prior overt heart disease. Effective prevention will require long-term prophylaxis by drugs in large numbers of people identified by risk factors. This means that safe as well as effective drugs are required. Drugs with overt effects on cardiac electrophysiology have failed in the clinic owing to poor effectiveness and/or adverse effects. This article examines possible new drug targets. We have focused on acute myocardial ischaemia as it is the most strikingly proarrhythmic pathology, and the most common cause of coronary artery disease-related VF and SCD according to inferences from epidemiology, drug trials and decades of animal research. To set the scene we have briefly explored drugs that have failed in the clinic in order to identify possible targets that have been overlooked or underexploited. We conclude that the best strategy is identification of pathology-specific targets that render drugs active only where and when their action is required. |
6,956 | Intermittent changing axis deviation during acute myocarditis. | It has been rarely reported intermittent changing axis deviation also during atrial fibrillation and also during atrial flutter. Intermittent changing axis deviation during acute myocardial infarction and changing axis deviation associated with atrial fibrillation and acute myocardial infarction too have been also rarely reported. Conduction system disturbances have been described during acute myocarditis and it has been suggested that myocardial interstitial edema is implicated in the conduction disturbances that occur in acute myocarditis. Usually, edema is located in the epicardial layer of ventricular wall during acute phase of focal myocarditis and it can't be associated with clear evidence of wall motion abnormalities. It has also been described in a work the report of sequences of alternatively normal and Wenckebach beats with alternate and progressive right bundle branch block interpreted as functional longitudinal dissociation in atrioventricular conduction axis during chronic chagasic myocarditis. We present a case of changing axis deviation during acute myocarditis in a 15-year-old Italian man. This case focuses attention on changing axis deviation during acute phase of focal myocarditis in absence of wall motion abnormalities. |
6,957 | Left atrial function after ablation for paroxysmal atrial fibrillation. | Radiofrequency ablation of the pulmonary veins has been used to treat patients with paroxysmal atrial fibrillation (AF), and atrial damage after ablation is an issue of concern. To evaluate left atrial function shortly and midterm after ablation, 33 consecutive patients with paroxysmal AF were studied at baseline, 24 hours, and > or =6 months after ablation. Patients in sinus rhythm with normal ventricular function were included in the study. Echocardiographic measurements of left atrial volumes (Simpson's rule) and transmitral and tissue Doppler myocardial (A') velocities at the septal and lateral mitral annulus were undertaken at each time. Left atrial emptying fraction (EF; maximal - minimal left atrial volume/maximal left atrial volume) was used to express left atrial function. After 8 +/- 2 months, 30 of 33 patients returned (23 men, age 53 +/- 13 years), and all except 2 were in sinus rhythm. Shortly after ablation, left atrial minimal volumes increased (from 30 +/- 15 to 35 +/- 15 ml; p = 0.02), with maximal volumes unchanged, resulting in decreased left atrial EF (from 47 +/- 8 to 40 +/- 7 ml; p <0.05). Tissue Doppler septal A' velocities also decreased (from 8.2 +/- 1.8 to 6.9 +/- 2.0 cm/s; p <0.05). However, after midterm follow-up, both left atrial EF and septal A' velocities had slightly increased compared with shortly after ablation, although left atrial volumes remained similar to baseline. Septal A' velocity changes paralleled left atrial EF both shortly (r = 0.46, p = 0.02) and at midterm after ablation (r = 0.47, p = 0.01). In conclusion, after radiofrequency ablation, patients with paroxysmal AF experienced an initial impairment in atrial function, with improvement at longer term follow-up. |
6,958 | Right atrial spontaneous echo contrast indicates a high incidence of perfusion defects in pulmonary scintigraphy in patients with atrial fibrillation. | This study investigated the relationship between right atrial SEC (RA-SEC) and silent pulmonary embolism (PE) in patients with nonvalvular atrial fibrillation (NVAF). Spontaneous echo contrast (SEC) within the cardiac chambers is associated with an increased risk of thromboembolism. However, most studies have examined the relationship between left atrial SEC and systemic thromboembolic disease. Transesophageal echocardiography (TEE) was performed in 210 patients with NVAF to assess a risk of thromboembolism. Right atrial SEC was detected in 37 patients, and 35 of these patients with RA-SEC and 29 patients without RA-SEC were enrolled in this study. However, patients with a history of symptomatic PE or deep vein thrombosis were excluded. Spontaneous echo contrast was diagnosed by TEE as the presence of smoke-like echoes that swirled in a circular pattern. PE was diagnosed by pulmonary scintigraphy. Thrombotic and thrombolytic parameters, including serum concentrations of plasmin-alpha-plasmin inhibitor complex (PIC), thrombin-antithrombin complex (TAT), D-dimer, and fibrinogen were measured in all patients. Left ventricular dimension, cardiac function, and hematologic parameters were similar in the two groups. Nevertheless, the incidence of perfusion defects in pulmonary scintigraphy was significantly higher in the group with RA-SEC (40%) than in the group without RA-SEC (7%; chi-square, P=0.006). The increased incidence of perfusion defects in pulmonary scintigraphy in patients with RA-SEC indicates that right atrial SEC may be a predictable factor at a high risk of PE. |
6,959 | Brugada-type electrocardiographic pattern induced by electrocution. | Heart is one of the most frequently affected organs in electrocution. Electrical injury can cause life-threatening cardiac complications such as asystole, ventricular fibrillation, and myocardial rupture. In this case report, we describe a 22-yr-old male patient who sustained electric burn injury and presented with electrocardiogram showing transient Brugada type pattern. |
6,960 | Theoretical possibility of ventricular fibrillation during use of TASER neuromuscular incapacitation devices. | TASER devices deliver electrical pulses that temporarily incapacitate suspects. This study analyzes the theoretical possibility of ventricular fibrillation (VF) induction by TASER currents.</AbstractText>Using finite element models (FEM), the results found that the skin, fat and anisotropic skeletal muscle layers attenuated a large portion of TASER currents, allowing just a fractional amount to penetrate transversally into deeper layers of tissue. The TASER current density reached 91 mA/cm(2), the threshold required to induce VF, at less than 14.7 mm away from the skin surface. This distance is significantly lower than the average skin-heart distance of 35 mm, as measured in subjects with a body-mass index (BMI) matched to that of typical in-custody suspects. The theoretical probability of inducing VF is significantly lower than 0.0000008, or 1:1,270,000. By comparison, the standard for basic safety and essential performance of medical electrical equipment, EN 60601-1, accepts as satisfactory a VF induction probability of 0.002, or 1:500.</AbstractText>The results indicated that TASER devices, while not risk free, have a very low cardiac risk profile when used for suspect temporary incapacitation.</AbstractText> |
6,961 | Predicting imminent episodes of ventricular tachyarrhythmia--retrospective analysis of short R-R records from ICD. | A predictor of an imminent episode of ventricular tachyarrhythmia, namely ventricular tachycardia and ventricular fibrillation has been developed. It only uses R-R records. The previous work was based on long R-R records stored in the memory of implantable cardioverter-defibrillators. With 1.8 hour of data, sensitivity of 53-83% can be achieved with corresponding specificity of 57-91%, depending on which set of criteria are used. The Medtronic ICD data series was made available to us. This consists of 135 pairs of files with 1024 R-R intervals. Each pair consists of a record that ends with the detection of the tachyarrhythmia, and a 'most recent' record just prior to the interrogation of the device. It was hoped that the 'most recent' record can be used to improve the specificity of the prediction algorithm. The predictor pattern was found in 29% of the arrhythmic records, and in 38% of the records with heart rate variability, namely SDNN, greater than 20 ms. This is comparable to the 40% results for similar conditions found earlier for records only 0.2 hr long. Unfortunately, due to a 'white coat effect', the predictor pattern was found in 40% of the 'most recent' records. While this new set of data has confirmed the sensitivity of the arrhythmia predictor, a fault in the data collection process this data set did not add to our understanding of the predictor behavior with a normal heart rhythm. |
6,962 | Phase space reconstruction approach for ventricular arrhythmias characterization. | Ventricular arrhythmias, especially tachycardia and fibrillation are one of the main causes of sudden cardiac death. Therefore, the development of methodologies, enable to detect their occurrence and to characterize their time evolution, is of fundamental importance. This work proposes a non-linear dynamic signal processing approach to address the problem. Based on the phase space reconstruction of the electrocardiogram (ECG), some features are extracted for each ECG time window. Features from current and previous time windows are provided to a dynamic neural network classifier, enabling arrhythmias detection and evolution trends assessment. Sensitivity and specificity values, evaluated from public MIT-BIH databases, show the effectiveness of the proposed strategy. |
6,963 | A simulation framework for dual chamber heart rhythm and cardiac pacing. | A previously developed open source computer model allows realistic simulation of ventricular intervals in atrial fibrillation, while taking into account of ventricular pacing. In this paper, we further improve this model and present a new simulation framework based on an integrated dual-chamber heart and pacer (IDHP) model. The IDHP model incorporates more realistic atrial and ventricular rhythm generators and an industry-standard dual-chamber pacemaker timing control logic. Moreover, it simulates various interactions between intrinsic heart activity and extrinsic cardiac pacing. The IDHP model provides a new simulation platform where it is possible to bench test advanced pacemaker algorithms in the presence of different types of cardiac rhythms. |
6,964 | Phase angle shift is a better determinant for catheter electrode contact with tissue compared to a catheter sensed electrogram. | Convention holds that the magnitude of an electrogram (EGM) recorded from an ablation catheter indicates proximity to the tissue and may be used to guide tip placement. The shift in capacitance (phase angle) as the electrode touches the tissue may be a better guide. We compared these two methods over a range of distances in close proximity to heart tissue. This study suggests that EGM is not a reliable predictor of proximity to tissue within a few millimeters of the surface. Thus, EGM alone should not be used to guide electrode placement for ablation, as a millimeter off the surface will shift a greater percentage of delivered energy to the blood pool rather than the target tissue. EGM should also not be used to gauge force of the catheter into tissue. Phase angle is a better predictor of both variables, but an optimal combination of predictors remains to be found. |
6,965 | Nonlinear analysis of the ECG during atrial fibrillation in patients for low energy internal cardioversion. | The goal of this study was to investigate the usefulness of nonlinear analysis in determining the success of low energy internal cardioversion (IC) in patients with atrial fibrillation (AF). Nonlinear analysis has previously been used for characterizing AF patterns, and spontaneous termination in its paroxysmal form. However, the relationship between the probability to restore sinus rhythm by IC and quantitative nonlinear analysis based electrocardiographic (ECG) markers has not been explored before. Thirty nine patients with AF, for elective DC cardioversion at the Royal Victoria Hospital in Belfast, were included in this study. One catheter was positioned in the right atrial appendage and another in the coronary sinus, to deliver a biphasic shock waveform. A voltage step-up protocol (50-300 V) was used for patient cardioversion. Residual atrial fibrillatory signal (RAFS) was derived from 60 seconds of surface ECG from defibrillator pads, prior to shock delivery, by bandpass filtering and ventricular activity (QRST) cancellation. QRST complexes were cancelled using a recursive least squared (RLS) adaptive filter. The maximal Lyapunov exponent (lambda), correlation dimension (course grained estimation, CDcg) and approximate entropy (ApEn) were extracted from the RAFS. These variables were calculated from 10 s of the RAFS before shock delivery. 26 patients were successfully cardioverted, employing a maximum energy of 11.84 joules. A lower lambda (0.037+/-0.006 vs. 0.044+/-0.008, P=0.01) and CDcg (5.552+/-2.075 vs. 6.592+/-1.130, P=0.049) were found in successfully cardioverted patients than in those non successful ones, with an energy <or=3 joules. Also, there was a significant positive correlation between the minimal defibrillation energy and lambda (r=0.483, P=0.013) in cardioverted patients. In conclusion, complexity analysis of the RAFS is useful for assessing the prospective efficacy of internal low energy cardioversion of patients with atrial fibrillation. |
6,966 | Constrained temporal extraction of the atrial rhythm in Atrial Fibrillation episodes. | The extraction of the Atrial Activity from the Ventricular Activity in Atrial Fibrillation episodes is a must for clinical analysis. We follow the semi Blind Source Extraction S-BSE approach to solve the problem. The proposed algorithm modifies the BSE contrast function to satisfy the prior knowledge about the spectral content of the atrial signal. The introduction of this prior allows obtaining a new algorithm with the following advantages: it allows the extraction of only the atrial component and it improves the quality of the recovered atrial signal in terms of spectral concentration as we show in the results. |
6,967 | Frequency distribution effects of anchored mother rotors--a computer model study. | Recent findings indicate that major organized centers (mother rotors) can maintain ventricular fibrillation (VF). In computer models the mother rotors can be induced by local shortening of the action potential duration (APD) in the cardiac tissue. Because of the fact that these rotors tend to drift away towards regions with longer APD, an additional heterogeneity (e.g. bundle) has to be included in the model for stabilizing the activation. Thus, the rotor anchors on this bundle and yields to interesting frequency distribution effects. In the dominant frequency (DF) map of a simplified computer model of the left ventricle it can be observed that the anchoring site of the rotor produces a slightly lower DF than in the surrounding cardiac tissue. That means that due to the load effect of the bundle the frequency is decreased. Furthermore the meandering of the mother rotor around this anchor site is reflected in the spectra of signals taken randomly in the organized region. These effects are both detected with two different independent spectral estimators with different resolutions. |
6,968 | A sensitive algorithm for automatic detection of space-time alternating signals in cardiac tissue. | Alternans, a beat-to-beat alternation in cardiac signals, may serve as a precursor to lethal cardiac arrhythmias, including ventricular tachycardia and ventricular fibrillation. Therefore, alternans is a desirable target of early arrhythmia prediction/detection. For long-term records and in the presence of noise, the definition of alternans is qualitative and ambiguous. This makes their automatic detection in large spatiotemporal data sets almost impossible. We present here a quantitative combinatorics-derived definition of alternans in the presence of random noise and a novel algorithm for automatic alternans detection using criteria like temporal persistence (TP), representative phase (RP) and alternans ratio (AR). This technique is validated by comparison to theoretically-derived probabilities and by test data sets with white noise. Finally, the algorithm is applied to ultra-high resolution optical mapping data from cultured cell monolayers, exhibiting calcium alternans. Early fine-scale alternans, close to the noise level, were revealed and linked to the later formation of larger regions and evolution of spatially discordant alternans (SDA). This robust new technique can be useful in quantification and better understanding of the onset of arrhythmias and in general analysis of space-time alternating signals. |
6,969 | Application of filtering methods for removal of resuscitation artifacts from human ECG signals. | Band-pass, Kalman, and adaptive filters are used for removal of resuscitation artifacts from human ECG signals. A database of separately recorded human ECG and animal resuscitation artifact signals is used for evaluation of the methods. The considered performance criterion is the signal-to-noise ratio (SNR) improvement, defined as the ratio of the SNRs of the filtered signal and the given ECG signal. The empirical results show that for low SNR of the given signal, a band-pass filter yields the best performance, while for high SNR, an adaptive filter yields the best performance. |
6,970 | Cardiac resynchronization therapy: long-term alternative to cardiac transplantation? | Cardiac transplantation remains the gold standard for treating end-stage heart failure. However, because of donor shortage and posttransplant complications alternative options are needed.</AbstractText>We investigated the impact of cardiac resynchronization therapy on clinical outcome in 545 patients with left bundle-branch block and interventricular asynchrony, who fulfilled the cardiac criteria for cardiac transplantation listing. Primary end point was heart failure death. Secondary end points were New York Heart Association class, functional (cardiopulmonary exercise tolerance, 6-minute hall walk distance), and morphologic (left ventricular end-diastolic diameter) factors.</AbstractText>The average follow-up period was 39.6 months (standard deviation, 26.1 months). In total, 1,784 years of observation were accrued. The percentage of nonresponders (no functional and morphologic improvement during follow-up) was 21.2%. One-year and 3-year freedom from heart failure death was 92.3% and 77.3%, respectively. Functional variables improved, but the left ventricular end-diastolic diameter decreased during the first 6 months of cardiac resynchronization therapy only in patients who survived during follow-up. Under cardiac resynchronization therapy, 42.5% (n = 34) of the cardiac transplantation candidates with atrial fibrillation at baseline returned to sinus rhythm.</AbstractText>Our data suggest that cardiac resynchronization therapy is a reliable long-term therapeutic option for the treatment of end-stage heart failure and intraventricular asynchrony.</AbstractText> |
6,971 | Distorted T-vector loop and increased heart rate are associated with ventricular fibrillation in a porcine ischemia-reperfusion model. | The ventricular repolarization (VR) response to short-lasting coronary occlusion has been characterized by 3-dimensional vectorcardiography during angioplasty in humans; the T-vector loop becomes distorted (increased T(avplan)) and more circular (decreased T(eigenvalue)), but these changes have not been related to ventricular arrhythmias.</AbstractText>The VR response was therefore explored in a porcine ischemia-reperfusion model and compared in pigs with (n = 16) vs without (n = 17) ventricular fibrillation (VF).</AbstractText>Different aspects of VR were evaluated at baseline, at maximum ischemia, before reperfusion and at the subsequent ST maximum, after 1 hour of reperfusion, and before VF. Three aspects of the VR response were assessed: the ST-segment, the T-vector angles, and the T-vector loop morphology.</AbstractText>All parameters changed significantly from baseline during ischemia and/or reperfusion. The early changes were similar to those previously observed in humans during angioplasty. The VF episodes were preceded by a significantly exaggerated T-loop distortion (increased T(avplan)) and increased heart rate.</AbstractText>Aggravated T-loop distortion might, in this porcine ischemia-reperfusion model, reflect aspects of VR relevant to arrhythmogenesis.</AbstractText> |
6,972 | [Effects of Shen-song-yang-xin capsule on ventricular arrhythmias in ischemia/reperfusion: experiment with rats]. | To investigate the effects of Shen-song-yang-xin capsule containing ginseng, ophiopogon root, red sage root, etc, on the ventricular arrhythmias caused by ischemic/reperfusion.</AbstractText>Thirty SD rats were randomly divided into 2 equal groups: Shen-song-yang-xin group undergoing gastric infusion of Shen-song-yang-xin 4 g x kg(-1) x d(-1) for 2 weeks and then subjected to left coronary artery occlusion for 30 minutes followed by reperfusion for 60 minutes, and control group undergoing ischemia/reperfusion only. Electrocardiography was conducted to record the ventricular arrhythmias, and after 60 minutes of reperfusion the rats were killed with their hearts removed to measure the infarction size.</AbstractText>(1) During the 30 minutes' ischemia, the average number of episode of ischemia-induced premature ventricular contraction of the Shen-song-yang-xin group was (6.7 +/- 0.3) beats/30 min, significantly lower than that of the control group [(15.0 +/- 1.1) beats/30 min, P = 0.007]; the average number of episode of ischemia-induced ventricular tachycardia of the Shen-song-yang-xin group was (3.5 +/- 0.2) episodes/30 min, significantly lower than that of the control group [(14.7 +/- 0.6) episodes/30 min, P = 0.003]; the duration of ventricular tachycardia of the Shen-song-yang-xin group was (10.3 +/- 2.0) s, significantly shorter than that of the control group [(28.3 +/- 4.6) s, P = 0.018]; and the duration of ventricular fibrillation of the Shen-song-yang-xin group was (7.0 +/- 1.1) s, significantly shorter than that of the control group [(15.0 +/- 1.7) s, P = 0.031]. (2) 60 minutes after the reperfusion, the number of episode of premature ventricular contraction of the Shen-song-yang-xin group was (5.3 +/- 0.8) beats/60 min, significantly lower than that of the control group [(15.6 +/- 1.8) beats/60 min, P = 0.002], and the duration of reperfusion-induced ventricular tachycardia was (4.6 +/- 0.5) s, significantly shorter than that of the control group [(13.5 +/- 0.6) s, P = 0.001].</AbstractText>Shen-song-yang-xin capsule significantly reduces the ischemia-induced ventricular arrhythmia, average episode number of reperfusion-induced premature ventricular contraction, and duration of reperfusion-induced ventricular tachycardia.</AbstractText> |
6,973 | Out-of-hospital ventricular fibrillation in three adolescents. | We describe three adolescents who experienced sudden cardiac arrest due to ventricular fibrillation in an out-of-hospital setting and survived with good neurological outcome despite delayed time to defibrillation. All three were treated with prolonged cardiopulmonary resuscitation (CPR) by certified basic life support providers prior to first defibrillation. This report stresses the importance of early, minimally interrupted, chest compression CPR in children who suffer sudden cardiac arrest in the out-of-hospital setting where defibrillation could be delayed. |
6,974 | [Antithrombotic therapy in primary and secondary stroke prevention of cardiac patients and in acute stroke]. | Primary vascular prevention: the prevalence of cardiogenic stroke will increase in the future. All patients with atrial fibrillation but without any ischemic stroke, must undergo a rigorous risk evaluation, which is crucial for pharmacotherapy. Atrial fibrillation is an important risk factor for stroke, therefore patients with atrial fibrillation should be anticoagulated (except those without other risk factors). Even patients over 75 years with atrial fibrillation could be anticoagulated if the INR is properly controlled. The authors review also the role of anticoagulation in patients suffering from myocardial infarction or valve diseases. Acute stroke: The new European stroke guideline does not recommend the use of conventional or fractionated heparin in the first three days of acute stroke, but aspirin therapy is recommended. Long-term anticoagulation is needed only if cardiac source of emboli can be verified, the patient has good compliance, and the risk of hemorrhagic complication is low (INR: 2-3). Otherwise, antiplatelet therapy is recommended. Some authors recommend early anticoagulation in special cases (high risk of embolisation, left atrial/ventricular thrombus, arterial dissection or surgical intervention for a severe arterial stenosis). Caution is needed in patients with large infarct, uncontrolled hypertension and microbleeds on MRI. Secondary prevention: Antiplatelet therapy is recommended for every post-stroke patient, but for those with cardiac source of emboli anticoagulation is recommended. |
6,975 | The predictive value of plasma brain natriuretic peptide for the recurrence of atrial fibrillation six months after external cardioversion. | The aim of this study was to assess the predictive value of plasma brain natriuretic peptide (BNP) level for the recurrence of atrial fibrillation (AF) after successful cardioversion in patients with persistent AF.</AbstractText>The study included 58 patients (36 females, 22 males; mean age 59 years) with preserved left ventricular function, who underwent successful electrical cardioversion for persistent AF. Plasma BNP levels were measured before, 30 minutes and six months after cardioversion and electrocardiography was performed to assess AF recurrence. Echocardiography was performed in all the patients before cardioversion.</AbstractText>At six months, 38 patients (65.5%) were in sinus rhythm (SR), whereas 20 patients (34.5%) reverted to AF. The mean baseline BNP level was significantly higher than that measured 30 minutes after cardioversion (255.6+/-159.6 pg/ml vs 70.5+/-57.0 pg/ml; p=0.00006). Patients who reverted to AF had significantly higher baseline (p=0.035) and six-month (p=0.001) BNP levels. In addition, they had a significantly greater decrease in BNP levels 30 minutes after cardioversion than patients who remained in SR (-271.9+/-42.4 pg/ml vs -139.4+/-25.3 pg/ml; p=0.008). ROC analysis of this drop with the cutoff value of 200 pg/ml predicted AF recurrence at six months with 80% sensitivity and 86% specificity. There were no correlations between baseline BNP level and duration of AF. However, left atrium diameter showed a significant negative correlation with the baseline BNP level (for = or <40 mm, 41-45 mm, and = or >45 mm: 394.6 pg/ml, 206.5 pg/ml, and 198.5 pg/ml, respectively; p=0.02).</AbstractText>In patients with persistent AF, baseline plasma BNP level and the magnitude of its decrease after successful cardioversion may predict AF recurrence.</AbstractText> |
6,976 | [Acute anterior myocardial infarction due to left main coronary artery thrombosis]. | Acute anterior myocardial infarction (MI) due to left main coronary artery thrombosis is a rare entity with a very high mortality rate. A 72-year-old male patient was admitted with chest pain of two-hour onset that appeared during syncope. Electrocardiography showed first-degree AV block, right bundle branch block, left anterior fascicular block, ST-segment elevation of 5 mm in lead aVR, and significant ST depression in anterior derivations, suggesting acute anterior MI. Coronary angiography showed total occlusion of the left main coronary artery. During consultation for emergency operation, he developed hypotension. An intra-aortic balloon pump was inserted and inotropic support was initiated. He required several attempts of cardioversion due to persistent attacks of ventricular tachycardia. He developed respiratory arrest, requiring endotracheal intubation mechanical ventilation. The patient died due to recurrent attacks of ventricular fibrillation and subsequent development of asystole during primary percutaneous coronary intervention. |
6,977 | Prediction of fatal or near-fatal cardiac arrhythmia events in patients with depressed left ventricular function after an acute myocardial infarction. | To determine whether risk stratification tests can predict serious arrhythmic events after acute myocardial infarction (AMI) in patients with reduced left ventricular ejection fraction (LVEF < or = 0.40).</AbstractText>A total of 5869 consecutive patients were screened in 10 European centres, and 312 patients (age 65 +/- 11 years) with a mean LVEF of 31 +/- 6% were included in the study. Heart rate variability/turbulence, ambient arrhythmias, signal-averaged electrocardiogram (SAECG), T-wave alternans, and programmed electrical stimulation (PES) were performed 6 weeks after AMI. The primary endpoint was ECG-documented ventricular fibrillation or symptomatic sustained ventricular tachycardia (VT). To document these arrhythmic events, the patients received an implantable ECG loop-recorder. There were 25 primary endpoints (8.0%) during the follow-up of 2 years. The strongest predictors of primary endpoint were measures of heart rate variability, e.g. hazard ratio (HR) for reduced very-low frequency component (<5.7 ln ms(2)) adjusted for clinical variables was 7.0 (95% CI: 2.4-20.3, P < 0.001). Induction of sustained monomorphic VT during PES (adjusted HR = 4.8, 95% CI, 1.7-13.4, P = 0.003) also predicted the primary endpoint.</AbstractText>Fatal or near-fatal arrhythmias can be predicted by many risk stratification methods, especially by heart rate variability, in patients with reduced LVEF after AMI.</AbstractText> |
6,978 | Revelation of Brugada electrocardiographic pattern during a febrile state associated with acute myocardial infarction. | 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 chest pain and ST elevation Brugada pattern during febrile states. We present a case of revelation of Brugada pattern in a 69-year-old Italian man during a febrile state associated with acute myocardial infarction. Also this report confirms that Brugada pattern should be considered as one of differential diagnoses when we examine the patients during a febrile state. |
6,979 | Early and late outcomes in minimally invasive mitral valve repair: an eleven-year experience in 707 patients. | This study analyzes a single institution experience with minimally invasive mitral valve repair and evaluates long-term surgical outcomes of morbidity, mortality, and rates of reoperation. Late follow-up of mitral regurgitation and left ventricular function were also assessed.</AbstractText>Between August 1996 and October 2007, minimally invasive mitral valve repair was performed in 713 patients (mean follow-up 5.7 years). Excluding 6 repairs with robotic assistance, an perspective analysis of the remaining 707 patients was carried forth. Mean age was 57 +/- 13 years. Mean preoperative ejection fraction was 60% +/- 10%. Surgical access was through a lower ministernotomy (74%), right parasternal incision (24%), right thoracotomy (1.4%), or upper ministernotomy (0.7%). Exposure of the mitral valve was through the left atrium in 58% of the cases and transeptal in 42%. A ring annuloplasty was incorporated into 680 (96%) of 707 repairs. The Kaplan-Meier and Student t test for paired samples were used for statistical analysis.</AbstractText>There were 3 (0.4%) operative deaths. Perioperative morbidity included new-onset atrial fibrillation (20%), reoperation for bleeding (2%), stroke (1.9%), permanent pacemaker implantation (1.7%), deep sternal wound infection (0.7%), and aortic dissection (0.4%). Median hospital stay was 5 days. Only 31% of patients required blood transfusion during the hospital course. There were 49 (6.9%) late deaths and 34 (4.8%) failed repairs necessitating reoperation. At 11.2 years, survival was 83% (95% confidence intervals, 76.5-88.1); freedom from reoperation was 92% (95% confidence intervals, 86.2-94.9). Nine (1.3%) patients were lost to follow-up. A total of 2369 patient-years of echocardiography time were obtained in 544 patients (mean 4.36 years, range 0.47-11.09). Mean grade of mitral regurgitation decreased from 3.80 to 1.42 (P < .0001) Mean left ventricular ejection fraction decreased from 60.7% to 56.3% (P < .0001). Combined risk of death, reoperation, and recurrence of moderately severe to severe mitral regurgitation was 7.7% (43/555).</AbstractText>Minimally invasive mitral valve repair is safe, with low perioperative morbidity, low rates of recurrent mitral regurgitation, and low rates of reoperation and death at late follow-up.</AbstractText> |
6,980 | Complex adrenergic and inflammatory mechanisms contribute to phase 2 ventricular arrhythmias in anaesthetized rats. | The mechanisms responsible for phase 2 (infarct-related) ventricular arrhythmias remain unclear. We have investigated the role of alpha(1) and beta(1) adrenoceptor activation and the interaction of this with infarct neutrophil accumulation, in anaesthetized rats.</AbstractText>Neutrophil-replete Sprague-Dawley rats (n = 8-9 per group) were anaesthetized and randomized to receive vehicle, prazosin (0.5 mg.kg(-1) i.v.), atenolol (4 mg.kg(-1) i.v.) or their combination prior to left main coronary artery occlusion. A further group was depleted of neutrophils and received both atenolol and prazosin. Coronary ligation in all groups was maintained for 240 min.</AbstractText>Atenolol and prazosin treatment lowered heart rates and blood pressures respectively, but neither agent given alone affected the incidence of phase 2 ventricular tachycardia or fibrillation. However, co-administration of atenolol with prazosin reduced phase 2 ventricular premature beats (log(10)-transformed totals were 1.25 +/- 0.26 vs. 2.43 +/- 0.18 in controls; P < 0.05). Neutrophil depletion attenuated this antiarrhythmic effect (log(10)-transformed total ventricular premature beats were 1.66 +/- 0.35; P > 0.05 vs. controls).</AbstractText>Phase 2 arrhythmias appear to depend in part on a complex interaction between catecholamines and neutrophils. A model of this interaction is proposed.</AbstractText> |
6,981 | Relationship between atrial fibrillation and blunted hyperemic myocardial blood flow in patients with hypertrophic cardiomyopathy. | Atrial fibrillation (AF) and coronary microvascular dysfunction (CMD) are common in hypertrophic cardiomyopathy (HCM), but whether they are associated is unclear. We assessed the relationship between AF and CMD in HCM.</AbstractText>Global hyperemic myocardial blood flow (hMBF) was measured in 95 HCM patients (16 with, 79 without paroxysmal or chronic AF) by N-13 ammonia positron emission tomography (PET) after dipyridamole infusion. AF patients were older (50.5 +/- 13.4 vs. 38.7 +/- 14.9 years, P < .0005), had larger left atrial diameter (49.8 +/- 7.4 vs 38.6 +/- 5.7 mm, P < .00001), and left ventricular end-systolic diameter (30.4 +/- 6.7 vs 25.5 +/- 5.3 mm, P < .005) compared with those in stable sinus rhythm. In patients with AF, hMBF was significantly lower (1.23 +/- 0.44 vs 1.87 +/- 0.90 mL/min/g, P < 0.0001). In multivariate logistic regression analysis, hMBF, left atrial diameter, and age were independently associated with AF (P < .05 for all).</AbstractText>HCM patients with paroxysmal or chronic AF have lower hMBF than those in stable sinus rhythm. The association between CMD and AF is independent of other known predictors of AF, suggesting a causal link between these two features.</AbstractText> |
6,982 | The additive prognostic value of perfusion and functional data assessed by quantitative gated SPECT in women. | The aim of this study was to assess the prognostic value of technetium-99m tetrofosmin gated SPECT imaging in women using quantitative gated single photon emission computed tomography (SPECT) imaging.</AbstractText>We followed 453 consecutive female patients. Average follow-up was 1.33 years (max. 2.55). Hard endpoints were cardiac death, acute myocardial infarction, or documented ventricular fibrillation. Event-free survival curves were obtained. Optimal cutoff values for left ventricular (LV) volumes, LV ejection fraction (LVEF), and perfusion data to predict outcome were determined by ROC curve analysis.</AbstractText>A total of 236 patients had an abnormal study, of whom 27 patients experienced hard events (16 deaths) and 47 patients soft events. For hard events summed stress score (SSS) and LVEF, and for any cardiac event SSS showed independent incremental prognostic value. The survival curves were maximally separated when using cutoff values for SSS of > or = 22 and LVEF < 52% (P < 0.001, HR 4.61 and P < 0.001 HR 5.24 for SSS and LVEF resp.), and SSS > or = 14 (P < 0.001 HR 3.76) for any cardiac event.</AbstractText>In women, perfusion and functional parameters derived from quantitative gated technetium-99m tetrofosmin SPECT imaging can adequately be used for cardiac risk assessment. Using quantitative gated SPECT, female patients with an LVEF < 52% or an SSS > or = 22 are at increased risk for subsequent hard events. Furthermore, patients with an SSS > or = 14 are at increased risk for any cardiac events.</AbstractText> |
6,983 | Electrical storm reversible by isoproterenol infusion in a striking case of early repolarization. | A 40-year-old woman was referred to intensive care unit after recurrent ventricular fibrillation. She was free of cardiac medical history or medications. The resting ECG displayed an extended early repolarization in the inferior leads and all the precordial leads. Incessant ventricular fibrillations justified a treatment by intravenous amiodarone associated with general anaesthesia and mechanical ventilation without success on ventricular fibrillation. Because of a low heart rate intravenous isoproterenol infusion was initiated. Isoproterenol infusion was associated with heart rate acceleration and a decrease in J point elevation and the disappearance of ventricular fibrillation episodes. No cardiac disease was documented and the patient was implanted of a single chamber ICD. Six months later the patient was free of syncope and ventricular fibrillation on ICD memory. This case report demonstrates the usefulness and efficiency of the isoproterenol infusion to eliminate recurrent ventricular fibrillation in patients with early repolarization. |
6,984 | Chamber-specific effects of hypokalaemia on ventricular arrhythmogenicity in isolated, perfused guinea-pig heart. | Diuretic-induced hypokalaemia has been shown to promote cardiac arrhythmias in hypertensive patients. The present study was designed to determine whether hypokalaemia increases arrhythmic susceptibility of the left ventricle (LV) or the right ventricle (RV), or both. Proarrhythmic effects of hypokalaemic perfusion (2.5 mm K(+) for 30 min) were assessed in isolated guinea-pig heart preparations using simultaneous recordings of volume-conducted electrocardiogram and monophasic action potentials from six ventricular epicardial sites. Effective refractory periods, ventricular fibrillation thresholds and inducibility of tachyarrhythmias by programmed electrical stimulation and tachypacing were determined at the LV and the RV epicardial stimulation sites. Hypokalaemia promoted spontaneous ventricular ectopic activity, an effect attributed to non-uniform prolongation of ventricular repolarization resulting in increased RV-to-LV transepicardial dispersion of refractoriness and action potential duration. Furthermore, hypokalaemic perfusion was associated with reduced ventricular fibrillation threshold and increased inducibility of tachyarrhythmias by programmed electrical stimulation and tachypacing as determined at the LV stimulation site. In contrast, the RV stimulation revealed no change in arrhythmic susceptibility of the RV chamber. Consistently, hypokalaemia reduced the LV effective refractory period but had no effect on the RV refractoriness. This change enabled generation of premature propagating responses by extrastimulus application at earlier time points during LV repolarization. Increased prematurity of extrastimulus-evoked propagating responses was associated with exaggerated local inhomogeneities in intraventricular conduction and action potential duration in hypokalaemic LV, thus creating a favourable stage for re-entrant tachyarrhythmias. Taken together, these findings suggest that proarrhythmic effects of hypokalaemia are mostly attributed to increased LV arrhythmogenicity in the guinea-pig heart. |
6,985 | A least mean-square filter for the estimation of the cardiopulmonary resuscitation artifact based on the frequency of the compressions. | Cardiopulmonary resuscitation (CPR) artifacts caused by chest compressions and ventilations interfere with the rhythm diagnosis of automated external defibrillators (AED). CPR must be interrupted for a reliable diagnosis. However, pauses in chest compressions compromise the defibrillation success rate and reduce perfusion of vital organs. The removal of the CPR artifacts would enable compressions to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. We have estimated the CPR artifact using only the frequency of the compressions as additional information to model it. Our model of the artifact is adaptively estimated using a least mean-square (LMS) filter. It was tested on 89 shockable and 292 nonshockable ECG samples from real out-of-hospital sudden cardiac arrest episodes. We evaluated the results using the shock advice algorithm of a commercial AED. The sensitivity and specificity were above 95% and 85%, respectively, for a wide range of working conditions of the LMS filter. Our results show that the CPR artifact can be accurately modeled using only the frequency of the compressions. These can be easily registered after small changes in the hardware of the CPR compression pads. |
6,986 | Increased N-terminal-pro-B-type natriuretic peptide levels in patients with appropriate implantable defibrillator therapies. | The ability to better identify predictors of implantable defibrillator therapies in patients with heart failure would allow the optimization of patient selection. N-terminal-Pro-B-type natriuretic peptide (NT-ProBNP) is secreted by the ventricles in response to myocardial stretching and is a sensitive marker of left ventricular dysfunction and cardiac mortality in patients with heart failure. We assessed the relationship between NT-ProBNP and defibrillator therapies for primary or secondary prevention of arrhythmic death.</AbstractText>NT-ProBNP levels were analyzed in 45 patients with stable heart failure symptoms and defibrillator devices, with and without device therapies, and appropriate and inappropriate therapies. Univariate and multivariate analyses were used to identify predictors of appropriate defibrillator therapies.</AbstractText>Device interventions occurred in 21 patients: 12 appropriate therapies and 9 inappropriate therapies. Patients with appropriate therapies had higher NT-ProBNP levels than patients with no device therapies (2469.1 +/- 2281.8 pg/mL vs 838.7 +/- 832 pg/mL; P = .0019), inappropriate therapies (730.4 +/- 503 pg/mL; P = .0046), and combined inappropriate plus no therapies (2469.1 +/- 2281.8 pg/mL vs 713.9 +/- 510.6 pg/mL; P = .0008). The NT-ProBNP level was the only independent predictor of appropriate device therapies during the observation period (P = .004).</AbstractText>Elevated NT-ProBNP was an independent predictor of appropriate defibrillator therapies. Extensive myocardial remodeling may create the electrophysiologic conditions necessary to elicit ventricular tachyarrhythmias. Further research is necessary to clarify whether the identification of a subgroup of higher risk may benefit from a more aggressive defibrillator programming.</AbstractText> |
6,987 | Aspects on the increase in bystander CPR in Sweden and its association with outcome. | To describe changes in the proportion of bystanders performing cardiopulmonary resuscitation (CPR) in out of hospital cardiac arrest (OHCA) in Sweden and to study the impact of bystander CPR on ventricular fibrillation and on survival during various times.</AbstractText>All patients who suffered from OHCA in Sweden in whom CPR was attempted and who were included in the Swedish cardiac arrest register (SCAR) between 1992 and 2005. Crew witnessed cases were excluded.</AbstractText>In all 34,125 patients were included in the survey. Among witnessed OHCA the proportion of patients receiving bystander CPR increased from 40% in 1992 to 55% in 2005 (p<0.0001). In non-witnessed OHCA the corresponding proportion increased from 22% to 44% (p<0.0001). There was a significant increase in bystander CPR regardless of age, sex and place. The increase was only found when CPR was performed by lay persons (21% in 1992 to 40% in 2005; p<0.0001). Bystander CPR was associated with an increased proportion of patients found in a shockable rhythm and a lower number of shocks to receive return of spontaneous circulation. Bystander CPR was associated with a similar increase in survival early and late in the evaluation.</AbstractText>There was a marked increase in bystander CPR in OHCA, when performed by lay persons, during the last 14 years in Sweden. Bystander CPR was associated with positive effects both on ventricular fibrillation and survival.</AbstractText> |
6,988 | Effects of stomach inflation on haemodynamic and pulmonary function during cardiopulmonary resuscitation in pigs. | Stomach inflation during cardiopulmonary resuscitation (CPR) is frequent, but the effect on haemodynamic and pulmonary function is unclear. The purpose of this study was to evaluate the effect of clinically realistic stomach inflation on haemodynamic and pulmonary function during CPR in a porcine model.</AbstractText>After baseline measurements ventricular fibrillation was induced in 21 pigs, and the stomach was inflated with 0L (n=7), 5L (n=7) or 10L air (n=7) before initiating CPR.</AbstractText>During CPR, 0, 5, and 10L stomach inflation resulted in higher mean pulmonary artery pressure [median (min-max)] [35 (28-40), 47 (25-50), and 51 (49-75) mmHg; P<0.05], but comparable coronary perfusion pressure [10 (2-20), 8 (4-35) and 5 (2-13) mmHg; P=0.54]. Increasing (0, 5, and 10L) stomach inflation decreased static pulmonary compliance [52 (38-98), 19 (8-32), and 12 (7-15) mL/cmH(2)O; P<0.05], and increased peak airway pressure [33 (27-36), 53 (45-104), and 103 (96-110) cmH(2)O; P<0.05). Arterial oxygen partial pressure was higher with 0L when compared with 5 and 10L stomach inflation [378 (88-440), 58 (47-113), and 54 (43-126) mmHg; P<0.05). Arterial carbon dioxide partial pressure was lower with 0L when compared with 5 and 10L stomach inflation [30 (24-36), 41(34-51), and 56 (45-68) mmHg; P<0.05]. Return of spontaneous circulation was comparable between groups (5/7 in 0L, 4/7 in 5L, and 3/7 in 10L stomach inflation; P=0.56).</AbstractText>Increasing levels of stomach inflation had adverse effects on haemodynamic and pulmonary function, indicating an acute abdominal compartment syndrome in this CPR model.</AbstractText> |
6,989 | Impact of QT variables on clinical outcome of genotyped hypertrophic cardiomyopathy. | Although QT variables such as its interval and/or dispersion can be clinical markers of ventricular tachyarrhythmia, few data exist regarding the role of QT variables in genotyped hypertrophic cardiomyopathy (HCM). Therefore, we analyzed QT variables in genotyped subjects with or without left ventricular hypertrophy (LVH).</AbstractText>QT variables were analyzed in 111 mutation and 43 non-mutation carriers who were divided into three groups: A, those without ECG abnormalities and echocardiographically determined LVH (wall thickness > or =13 mm); B, those with ECG abnormalities but LVH; and C, those with ECG abnormalities and LVH. We also examined clinical outcome of enrolled patients.</AbstractText>Maximal LV wall thickness in group C (19.0 +/- 4.3 mm, mean +/-SD) was significantly greater than that in group A (9.2 +/- 1.8) and group B (10.4 +/- 1.8). Under these conditions, maximum QTc interval and QT dispersion were significantly longer in group C than those in group A (438 +/- 38 ms vs 406 +/- 30 and 64 +/- 31 vs 44 +/- 18, respectively; P < 0.05). QTc interval and QT dispersion in group B (436 +/- 50 and 64 +/- 22 ms) were also significantly greater than those in group A. During follow-up periods, four sudden cardiac deaths and one ventricular fibrillation were observed in group C, and two nonlethal ventricular tachyarrhythmias were observed in group B.</AbstractText>Patients with HCM-related gene mutation accompanying any ECG abnormalities frequently exhibited impaired QT variables even without LVH. We suggest that careful observation should be considered for those genotyped subjects.</AbstractText> |
6,990 | Antiarrhythmic drug therapy for atrial fibrillation: focus on atrial selectivity and safety. | Atrial fibrillation (AF) is a highly prevalent arrhythmia and responsible for significant morbidity, mortality and health care cost. The prevalence of AF is expected to increase markedly with the aging population. The use of conventional antiarrhythmic agents has been limited by potentially fatal ventricular proarrhythmia. Rhythm control could become the preferred treatment strategy for AF if antiarrhythmic agents that are similarly or more effective, but safer, than currently approved AF agents become available. A subanalysis of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial data showed that normal sinus rhythm confers a survival benefit in AF, suggesting that rhythm control, if achieved without the adverse effects related to current antiarrhythmic medications, may offer a significant survival advantage over rate control. Considerable work has been performed to explore novel, potentially safer antiarrhythmic drug targets for AF therapy, and some of these drug targets are currently being tested in experimental and clinical proof of concept studies. This article summarizes relevant aspects of the cellular electrophysiology of AF and reviews the actions of pharmacological agents being considered for the prevention and treatment of AF, focusing on atrial selective antiarrhythmic agents. A variety of drugs that inhibit the atrium-specific ultra rapid delayed rectifier potassium current (IKur) are being evaluated pre-clinically, but human experience with these agents is limited. The acetylcholine-activated current (IKACh) is another novel candidate target for atrial-specific drug therapy. The constitutively active form of this current is increased in human AF and pharmacological inhibition might be of therapeutic value. Certain drugs have IKACh blocking properties, but similar to IKur-blockers, none have been shown to have pure selectivity for this current. Newer agents being studied also include gap junction modulators and angiotensin-converting enzyme inhibitors. There is great hope that at least some of these agents will ultimately be available for effective and safer clinical treatment and prevention of AF. |
6,991 | Lack of clinical predictors of optimal V-V delay in patients with cardiac resynchronization devices. | Cardiac resynchronization therapy (CRT) is a well-established therapy for patients with moderate-to-severe heart failure (HF), left ventricular dysfunction with an ejection fraction <or= 35% and a QRS on the surface electrocardiogram of >or=130 msec. Device optimization is often performed, adjusting the timing of RV and LV stimulation to produce a pacing sequence that yields the best global cardiac performance. However, no standard guidelines exist for optimization and many invasive and non-invasive techniques have been employed with mixed results. The aim of the present study was to determine whether there are any clinical predictors of the optimal V-V settings in patients implanted with CRT devices.</AbstractText>We prospectively evaluated 47 consecutive patients with HF who were referred to our device optimization clinic. The mean patient age was 64.9 +/- 12.7 years. Patients were in both sinus rhythm (83%) and atrial fibrillation. Prior to device implant, 51% of patients had left bundle branch block (LBBB), 17% had intra-ventricular conduction delay (IVCD) and 21% were RV paced. Sixty-two percent were male, the mean QRS duration was 152 +/- 29 ms, mean LVEF 26 +/- 8% and 60% had a non-ischemic cardiomyopathy. Overall, 82% of patients required sequential pacing with 69% requiring LV pre-excitation to produce the best global cardiac function as determined by aortic velocity time integrals (VTI). In our cohort, none of the clinical characteristics evaluated, including etiology of the cardiomyopathy, QRS duration, LVEF, pre-implant rhythm or AV delay were predictive of an optimal simultaneous or sequential V-V setting.</AbstractText>None of the clinical variables tested in our analysis predicted optimal RV-LV settings. Our results suggest that individual optimization and programming of V-V settings is necessary. The inability to predict optimal settings likely reflects the unique characteristics of each patient and supports the need for individualized programming of each device.</AbstractText> |
6,992 | Reversible cardiomyopathy provoked by focal ventricular arrhythmia originating from the base of the posterior papillary muscle. | A new distinct clinical syndrome comprising of ventricular tachycardia or frequent premature beats arising from the base of the posterior papillary muscle has recently been reported. The cardiac arrhythmia had a non-reentrant mechanism and none of the patients had left ventricular dysfunction.</AbstractText>We report on a 55-year-old female patient presenting with a dilated cardiomyopathy and frequent ventricular premature beats (VPB). Ventricular arrhythmia was refractory to amiodarone. Eighteen months after the onset of palpitations the patient evolved from NYHA functional class I to class III, with a LVEF of 38%. VPB comprised 26% of the total number of QRS complexes during 24 h Holter monitoring, which also recorded 12 salvos of non-sustained VT. NT-pro BNP level was 1,080 mcg/ml. During electrophysiologic study LV geometry was reconstructed with Ensite NAVX system which allowed voltage and activation mapping. We found neither scar-like nor low-voltage tissue in the endocardial surface of the LV. VPB was mapped in a site at the base of the posterior papillary muscle, which was confirmed by LV angiography. Cool-tip catheter ablation successfully eliminated VPB. Three months later, the patient was in NYHA functional class I, NT-proBNP level was 98 mcg/ml, with partial LV reverse remodeling and LVEF of 58%. Twenty-four hours Holter monitoring showed only 24 single premature beats.</AbstractText>Focal ventricular arrhythmia arising from the base of the left posterior papillary muscle can provoke significant left ventricular dysfunction. Left ventricular dysfunction reversed after elimination of the VPB.</AbstractText> |
6,993 | Demonstration of left ventricular dyssynchrony and resynchrony by ECG-gated SPECT with cardioGRAF in a patient with advanced heart failure and narrow QRS complex. | Accurate objective quantification of left ventricular (LV) dyssynchrony is a key to selecting candidates for cardiac resynchronization therapy (CRT), especially when screening among patients with a narrow QRS. CardioGRAF (cardio Gated single photon emission computed tomography Regional Assessment for left ventricular Function), a newly developed LV segmental time-volume analyzing program for myocardial perfusion single photon emission tomography, may be a promising tool. We describe the case of a 63-year-old male with non-ischemic cardiomyopathy with a QRS duration of 112 ms, in whom cardioGRAF successfully demonstrated baseline LV dyssynchrony and resynchronization achieved by CRT as evidenced by a significant decrease in dyssynchrony index (standard deviation of the duration from R to end-systole among 17 LV segments) x100/R-R interval). |
6,994 | An unusual resolution of T-wave oversensing in an implantable cardioverter defibrillator in a child with long QT syndrome. | T-wave oversensing poses a clinical challenge often resulting in inappropriate therapies and shocks. T-wave oversensing can often be resolved by certain programmable adjustments while accepting a small risk of undersensing ventricular fibrillation. The following case depicts a girl with LQT whose transvenous defibrillator repeatedly demonstrated T-wave oversensing despite optimizing various programmable features and a separate pace/sense lead. Utilization of an LV epicardial pace/sense lead with stable R-waves affirmed an unusual resolution of T-wave oversensing and avoidance of inappropriate shocks. |
6,995 | The natural history of asymptomatic ventricular pre-excitation a long-term prospective follow-up study of 184 asymptomatic children. | The aim of this study was to describe the natural history of asymptomatic ventricular pre-excitation in children and to determine predictors of potentially life-threatening arrhythmic events.</AbstractText>Sudden death can be the first clinical manifestation in asymptomatic children with ventricular pre-excitation, but reduction of its incidence by prophylactic ablation requires the identification of subjects at high risk.</AbstractText>Between 1995 and 2005 we prospectively collected clinical and electrophysiologic data from 184 children (66% male; median age 10 years; range 8 to 12 years) with asymptomatic ventricular pre-excitation on the electrocardiogram. After electrophysiologic testing, subjects were followed as outpatients taking no medications. The primary end point of the study was the occurrence of arrhythmic events. Predictors of potentially life-threatening arrhythmias were analyzed.</AbstractText>Over a median follow-up of 57 months (min/max 32/90 months) after electrophysiologic testing, 133 children (mean age 10 years; range 8 to 12 years) did not experience arrhythmic events, remaining totally asymptomatic, while 51 children had within 20 months (min/max 8/60 months) a first arrhythmic event, which was potentially life-threatening in 19 of them (mean age 10 years; range 10 to 14 years). Life-threatening tachyarrhythmias resulted in cardiac arrest (3 patients), syncope (3 patients), atypical symptoms (8 patients), or minimal symptoms (5 patients). Univariate analysis identified tachyarrhythmia inducibility (p < 0.001), anterograde refractory period of accessory pathways (APERP) </=240 ms (p < 0.001), and multiple accessory pathways (p < 0.001) as risk factors for potentially life-threatening arrhythmic events. Independent predictors by multivariate analysis were APERP (p = 0.001) and multiple accessory pathway (p = 0.001).</AbstractText>These findings are potentially relevant in terms of early identification of high-risk asymptomatic children with ventricular pre-excitation. Subjects with short APERPs and multiple pathways are at higher risk of developing life-threatening arrhythmic events and are the best candidates for prophylactic ablation.</AbstractText> |
6,996 | [Pharmacologic treatment of atrial fibrillation].<Pagination><StartPage>303</StartPage><EndPage>308</EndPage><MedlinePgn>303-8</MedlinePgn></Pagination><Abstract><AbstractText>Atrial fibrillation is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function. It is a common arrhythmia that presents various treatment options. Pharmacologic therapy is used to maintain sinus rhythm, to control the ventricular response, or to convert atrial fibrillation to sinus rhythm and prevention of thromboembolism. Cardioversion shocks are applied through surface or intrathoracic electrodes to convert atrial fibrillation to sinus rhythm. The tendency for recurrence of atrial fibrillation is high. Treatment with antiarrhythmic drugs has decreased its recurrence. Drugs that slow conduction through the AV node (such as digoxin, beta blockers and calcium channel blockers) have been used as adjuvants to therapy for the prevention of atrial fibrillation. Drugs used for the prevention of atrial fibrillation are antiarrhythmic drugs of class IA and C, and type III. Drug combination acting through different electrophysiological channels and mechanisms may prove beneficial in the prevention of atrial fibrillation.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Lelakowski</LastName><ForeName>Jacek</ForeName><Initials>J</Initials></Author></AuthorList><Language>pol</Language><PublicationTypeList><PublicationType UI="D016421">Editorial</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016454">Review</PublicationType></PublicationTypeList><VernacularTitle>Leczenie farmakologiczne migotania przedsionków.</VernacularTitle></Article><MedlineJournalInfo><Country>Poland</Country><MedlineTA>Pol Merkur Lekarski</MedlineTA><NlmUniqueID>9705469</NlmUniqueID><ISSNLinking>1426-9686</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000319">Adrenergic beta-Antagonists</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000889">Anti-Arrhythmia Agents</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D002121">Calcium Channel Blockers</NameOfSubstance></Chemical><Chemical><RegistryNumber>73K4184T59</RegistryNumber><NameOfSubstance UI="D004077">Digoxin</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000319" MajorTopicYN="N">Adrenergic beta-Antagonists</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000889" MajorTopicYN="N">Anti-Arrhythmia Agents</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="Y">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName><QualifierName UI="Q000188" MajorTopicYN="Y">drug therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002121" MajorTopicYN="N">Calcium Channel Blockers</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004077" MajorTopicYN="N">Digoxin</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D055502" MajorTopicYN="N">Secondary Prevention</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D013923" MajorTopicYN="N">Thromboembolism</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading></MeshHeadingList><NumberOfReferences>8</NumberOfReferences></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="entrez"><Year>2009</Year><Month>1</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2009</Year><Month>1</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2009</Year><Month>3</Month><Day>20</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">19145926</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">19145816</PMID><DateCompleted><Year>2009</Year><Month>03</Month><Day>09</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>18</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1019-5297</ISSN><JournalIssue CitedMedium="Print"><Issue>3-4</Issue><PubDate><Year>2008</Year><Season>Apr-Jun</Season></PubDate></JournalIssue><Title>Likars'ka sprava</Title><ISOAbbreviation>Lik Sprava</ISOAbbreviation></Journal>[Structure peculiarities, conditions and factors preceding the development of heart rhythm disorder in Chernobyl cleanup workers]. | Atrial fibrillation is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function. It is a common arrhythmia that presents various treatment options. Pharmacologic therapy is used to maintain sinus rhythm, to control the ventricular response, or to convert atrial fibrillation to sinus rhythm and prevention of thromboembolism. Cardioversion shocks are applied through surface or intrathoracic electrodes to convert atrial fibrillation to sinus rhythm. The tendency for recurrence of atrial fibrillation is high. Treatment with antiarrhythmic drugs has decreased its recurrence. Drugs that slow conduction through the AV node (such as digoxin, beta blockers and calcium channel blockers) have been used as adjuvants to therapy for the prevention of atrial fibrillation. Drugs used for the prevention of atrial fibrillation are antiarrhythmic drugs of class IA and C, and type III. Drug combination acting through different electrophysiological channels and mechanisms may prove beneficial in the prevention of atrial fibrillation.</Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Lelakowski</LastName><ForeName>Jacek</ForeName><Initials>J</Initials></Author></AuthorList><Language>pol</Language><PublicationTypeList><PublicationType UI="D016421">Editorial</PublicationType><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016454">Review</PublicationType></PublicationTypeList><VernacularTitle>Leczenie farmakologiczne migotania przedsionków.</VernacularTitle></Article><MedlineJournalInfo><Country>Poland</Country><MedlineTA>Pol Merkur Lekarski</MedlineTA><NlmUniqueID>9705469</NlmUniqueID><ISSNLinking>1426-9686</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000319">Adrenergic beta-Antagonists</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D000889">Anti-Arrhythmia Agents</NameOfSubstance></Chemical><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D002121">Calcium Channel Blockers</NameOfSubstance></Chemical><Chemical><RegistryNumber>73K4184T59</RegistryNumber><NameOfSubstance UI="D004077">Digoxin</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000319" MajorTopicYN="N">Adrenergic beta-Antagonists</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D000889" MajorTopicYN="N">Anti-Arrhythmia Agents</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="Y">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="N">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName><QualifierName UI="Q000188" MajorTopicYN="Y">drug therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002121" MajorTopicYN="N">Calcium Channel Blockers</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004077" MajorTopicYN="N">Digoxin</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D055502" MajorTopicYN="N">Secondary Prevention</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D013923" MajorTopicYN="N">Thromboembolism</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading></MeshHeadingList><NumberOfReferences>8</NumberOfReferences></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="entrez"><Year>2009</Year><Month>1</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2009</Year><Month>1</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2009</Year><Month>3</Month><Day>20</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">19145926</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">19145816</PMID><DateCompleted><Year>2009</Year><Month>03</Month><Day>09</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>18</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1019-5297</ISSN><JournalIssue CitedMedium="Print"><Issue>3-4</Issue><PubDate><Year>2008</Year><Season>Apr-Jun</Season></PubDate></JournalIssue><Title>Likars'ka sprava</Title><ISOAbbreviation>Lik Sprava</ISOAbbreviation></Journal><ArticleTitle>[Structure peculiarities, conditions and factors preceding the development of heart rhythm disorder in Chernobyl cleanup workers].</ArticleTitle><Pagination><StartPage>22</StartPage><EndPage>30</EndPage><MedlinePgn>22-30</MedlinePgn></Pagination><Abstract>3595 participants of liquidation of consequences of Chernobyl accident (LCA) have been follow-upped since 1986. Structure and factors prior the development of heart rhythm derangements, results of physical examination, tonometry, ECG daily monitoring with taking into account the variability of heart rhythm, data of echocardiography with Doppler analysis have been established in 742 patients. Extrasystolic arrhythmia (50.8%) and atrium fibrillation prevailed in clinical structure of clinical structure of heart rhythm disorders (HRD). Etiological factors of HRD in 91.1% of cases were ischemic heart disease (IHD), hypertension and especially their combination, in 4.6%--other disorders, 4.6%--idiopathic HRD. It is possible to address special significance among factors before the development of HRD the following ones: participation in LCA since 1986, shift team work, ionizing radiation > or = 25 c3B, negative thoughts and memory about these events, from style of living--smoking habit, professional contact with xenobiotics, increased levels of arterial pressure, cholesterin, body weight index. Especial attention should be given to as predictors of the development of HRD -increased myocardium weight index > or = 170 gr/M2, duration of common and painless myocardial ischemia, basal frequency of heart rhythm > or = 75 b./m. It was established reliable relation between ventricular extrasystole and decreased of common BCP (r = -0.57; P < 0.05), spectrum power, (r = -0.52; P < 0.05), correlation disorder between its components. It is logical there was influence caused by combination of factors arised in connection with Chernobyl accident, life style and structural and functional changes of myocardium, hypertension and ischemic heart disease which are often found in Chernobyl disaster fighters. |
6,997 | Advanced cardiac life support and defibrillation in severe hypothermic cardiac arrest. | The application of Advanced Cardiac Life Support (ACLS) in severe hypothermic cardiac arrest remains controversial. While the induction of mild hypothermia has been shown to improve outcomes in patients already resuscitated from cardiac arrest, it is unknown whether ACLS protocols are effective during the resuscitation of the severely hypothermic cardiac arrest patient. We describe a case of a 47-year-old man who was successfully resuscitated from a ventricular fibrillation (VF) arrest with a core body temperature of 26.4 degrees C. The patient had been found unresponsive in a bathtub of cold water following an apparent suicide attempt. An incorrect pronouncement of death by the fire department delayed his transport to the hospital by more than four hours. Once in the emergency department (ED), the patient sustained a VF cardiac arrest and was successfully defibrillated using ACLS protocols. He ultimately survived his hospitalization with near-complete neurologic recovery. In this case report, we discuss the application of ACLS to the resuscitation of the hypothermic cardiac arrest patient as well as the issues involved in the prehospital determination of death. |
6,998 | Antiarrhythmic and arrhythmogenic effects of L-carnitine in ischemia and reperfusion. | Isolated rat hearts were subjected to 30-min coronary artery occlusion followed by 120-min reperfusion. The hearts (n=8-12) were perfused with Krebs-Henseleit solution enriched with L-carnitine (0.5, 2.5 and 5 mM) for 10 min before and after ischemia or reperfusion and for the whole period of ischemia and reperfusion. Two-hour perfusion with L-carnitine during ischemia/reperfusion markedly (p<0.05) and dose-dependently decreased the incidence of ventricular tachycardia (VT, maximum 65%). The incidence of reperfusion ventricular fibrillation (VF) also decreased from 63% (control) to 17% in hearts perfused with 5 mM L-carnitine, as reflected by a significant (p<0.05) decline in VF duration from 218+/-99 sec in control to 19+/-19 sec. Perfusion of etomoxir (palmitoylcarnitinetransferase-1 inhibitor) along with L-carnitine reversed the antiarrhythmogenic action of L-carnitine. Interestingly, short time preischemic administration of L-carnitine produced a concentration-dependent arrhythmogenic effects on both ischemia and reperfusion-induced arrhythmias. These results show that L-carnitine produced a protective effect against reperfusion arrhythmias only when it was perfused for the whole period of the experiment. This protective action was reversed by concomitant use of etomoxir, suggesting that the efficacy of L-carnitine is due to its mitochondrial action but cannot be solely attributed to increased fatty acid oxidation. |
6,999 | High defibrillation threshold in patients with implantable defibrillator: how effective is the subcutaneous finger lead? | Even in the era of high output implantable cardioverter defibrillator (ICD) devices, a certain proportion of patients cannot be successfully defibrillated with 10 J safety margin. In practice, either the use of a single- or double-coil lead does not guarantee successful termination of induced ventricular fibrillation. Therefore, we investigated the effectiveness of the subcutaneous finger lead placed at the subcutaneous tissue dorsal to the left ventricle in terms of defibrillation threshold (DFT) lowering.</AbstractText>Two thousand, eight hundred and three consecutive, unselected patients underwent first-time ICD implantation or ICD device exchange from 6/1999 through 3/2007. The mean age of the patients was 65.4 years. A total of 79.3% of the patients were male. The only implanted subcutaneous lead was the 6996 model by Medtronic Inc.</AbstractText>One hundred and seventy-seven patients (6.3%) received a subcutaneous finger lead implantation. According to the current institutional DFT testing protocol, any failure of the two standard DFT tests in first-time ICD implantation or a failure at the single test in ICD exchange operations was the trigger for subcutaneous finger lead implantation. The proportion of subcutaneous finger lead implantations increased parallel to a markedly larger amount of implantations. Since high output devices became standard, the implantation number of subcutaneous finger leads decreases. The mean of unsuccessful DFTs prior to subcutaneous finger lead implantation was 27.2+/-5.3 J. After subcutaneous finger lead implantation, the mean successful DFT was 17.9+/-3.3 J. No complication due to subcutaneous finger lead implantation occurred.</AbstractText>The subcutaneous finger lead is a quick, safe and effective method for DFT lowering.</AbstractText> |
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