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6,000 | Single coronary artery presenting as angina. | The authors present an unusual case of chest pain in an 84-year-old Caucasian woman. |
6,001 | Severe mitral regurgitation due to right ventricular apical pacing. | A 75-year-old man with history of paroxysmal atrial fibrillation developed acute pulmonary oedema immediately after permanent pacemaker insertion for symptomatic bradycardia and was transferred to our institution. Echocardiography prior to pacemaker insertion showed normal left ventricle (LV) function and mild mitral regurgitation (MR). A single-chamber pacemaker had been inserted with the ventricular lead positioned in the right ventricular apex. He was treated with diuretics with symptomatic improvement. Investigations failed to reveal a cause for cardiac failure. Patient subsequently had multiple readmissions for heart failure and echocardiography revealed severe MR. Patient was referred for mitral valve (MV) surgery. Intraoperatively, when patient was in sinus rhythm and not paced, transoesophageal echocardiogram showed a significant reduction in the severity of MR. MV surgery was aborted and further echocardiographic characterisation revealed worsening of MR during ventricular pacing. The device was upgraded to a dual-chamber system and programmed to atrial pacing with intrinsic ventricular rhythm. He has had no further admissions over the following year. |
6,002 | A young mountaineer surviving sudden cardiac arrest at high altitude. | A young mountaineer suffered from sudden cardiac arrest at high altitude. Cardiopulmonary resuscitation was initiated immediately. After 30 min a rescue team arrived and successfully defibrillated ventricular fibrillation upon which spontaneous circulation returned. The subsequent ECG was suggestive of extensive anterior myocardial infarction. Therefore, the patient was thrombolysed and transferred for primary percutaneous coronary intervention. Echocardiography revealed severely reduced left ventricular function with antero-septo-apical akinesia. However, angiography showed unobstructed coronary arteries. The patient fully recovered and left ventricular function normalised within 2 weeks. It may be speculated that exposure to high altitude resulted in acute coronary thrombosis which dissolved by rapid thrombolysis. |
6,003 | Protective head-cooling during cardiac arrest and cardiopulmonary resuscitation: the original animal studies. | Prolonged standard cardiopulmonary resuscitation (CPR) does not reliably sustain brain viability during cardiac arrest. Pre-hospital adjuncts to standard CPR are needed in order to improve outcomes. A preliminary dog study demonstrated that surface cooling of the head during arrest and CPR can achieve protective levels of brain hypothermia (30°C) within 10 minutes. We hypothesized that protective head-cooling during cardiac arrest and CPR improves neurological outcomes. Twelve dogs under light ketamine-halothane-nitrous oxide anesthesia were arrested by transthoracic fibrillation. The treated group consisted of six dogs whose shaven heads were moistened with saline and packed in ice immediately after confirmation of ventricular fibrillation. Six control dogs remained at room temperature. All 12 dogs were subjected to four minutes of ventricular fibrillation and 20 minutes of standard CPR. Spontaneous circulation was restored with drugs and countershocks. Intensive care was provided for five hours post-arrest and the animals were observed for 24 hours. In both groups, five of the six dogs had spontaneous circulation restored. After three hours, mean neurological deficit was significantly lower in the treated group (P=0.016, with head-cooled dogs averaging 37% and the normothermic dogs 62%). Two of the six head-cooled dogs survived 24 hours with neurological deficits of 9% and 0%, respectively. None of the control group dogs survived 24 hours. We concluded that head-cooling attenuates brain injury during cardiac arrest with prolonged CPR. We review the literature related to the use of hypothermia following cardiac arrest and discuss some promising approaches for the pre-hospital setting. |
6,004 | [Parameters of heart rhythm variability and QT-interval in patients with ischemic heart disease and type 2 diabetes]. | We studied parameters of heart rhythm variability and QT intervals in 141 patients (mean age 52.4 +/- 7.3 years) with unstable angina and acute myocardial infarction; 101 of these patients (71.6%) had type 2 diabetes. We found that in patients with diabetes parameters RRNN, LF and LF/HF were significantly lower. In patients with diabetes and risk of microangiopathy lowering of LF was maximal and correlated with elevation of glycosylated hemoglobin. In patients with diabetes and neuropathy significant reduction of power in HF range and increase of maximal corrected QT-interval value were observed. It is possible, that in patients with ischemic heart disease type 2 diabetes causes decrease of tone of vegetative nervous system mainly due to activity of parasympathetic part and this is accompanied by impaired repolarization of cardiac ventricles. |
6,005 | Platelets and cardiac arrhythmia. | Sudden cardiac death (SCD) remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g., serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic-acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium, and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products. |
6,006 | Anti- or profibrillatory effects of Na(+) channel blockade depend on the site of application relative to gradients in repolarization. | Sodium channel blockers are associated with arrhythmic sudden death, although they are considered antiarrhythmic agents. The mechanism of these opposing effects is unknown. We used a model of induction of ventricular fibrillation (VF) based on selective perfusion of the vascular beds of isolated porcine hearts (n = 8). One bed was perfused with sotalol (220 μM), the adjacent bed with pinacidil (80 μM), leading to repolarization heterogeneity (late repolarization in the sotalol-, early in the pinacidil-area). Premature stimulation from the area with the short action potential was performed. Epicardial activation/repolarization mapping was done. In three of the eight hearts VF was inducible prior to infusion of flecainide. In those hearts the Fibrillation Factor (FF), the interval between the earliest repolarization of the premature beat (S2) in the early repolarizing (pinacidil) domain, and the last S2-activation in the late repolarizing (sotalol) domain, was significantly shorter than in the hearts without VF (33 ± 22 vs 93 ± 11 ms, m ± SEM, p < 0.05). In the three hearts with VF flecainide was infused in the pinacidil domain after defibrillation. This led to shortening of the line of block, local delay of S2 activation and repolarization, an increase in FF and failure to induce VF. In the five hearts without VF, flecainide was subsequently infused in the sotalol domain. This led to a local delay of S2 activation, a shortening of FF (by 47 ± 3 ms) and successful induction of VF in three hearts. In the two remaining hearts FF did not decrease enough (maximally 13 ms) to allow re-entry. Sodium channel blockade applied to myocardium with a short refractory period is antifibrillatory whereas sodium channel blockade of myocardium with a long refractory period is profibrillatory. Our study provides a mechanistic basis for pro- and antiarrhythmic effects of sodium channel blockers in the absence of structural heart disease. |
6,007 | Ventricular tachyarrhythmias (out-of-hospital cardiac arrests). | Pulseless ventricular tachycardia and ventricular fibrillation are the main causes of sudden cardiac death, but other ventricular tachyarrhythmias can occur without haemodynamic compromise. Ventricular arrhythmias occur mainly as a result of myocardial ischaemia or cardiomyopathies, so risk factors are those of cardiovascular disease.</AbstractText>We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of electrical therapies for out-of-hospital cardiac arrest associated with ventricular tachycardia or ventricular fibrillation? What are the effects of antiarrhythmic drug treatments for use in out-of-hospital cardiac arrest associated with shock-resistant ventricular tachycardia or ventricular fibrillation? What are the effects of treatments for comatose survivors of out-of-hospital cardiac arrest associated with ventricular tachycardia or ventricular fibrillation? We searched: Medline, Embase, The Cochrane Library, and other important databases up to February 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).</AbstractText>We found 15 systematic reviews and RCTs that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.</AbstractText>In this systematic review we present information relating to the effectiveness and safety of the following interventions: amiodarone, bretylium, defibrillation, lidocaine, procainamide, and therapeutic hypothermia.</AbstractText> |
6,008 | Serum cardiac troponin I is related to increased left ventricular wall thickness, left ventricular dysfunction, and male gender in hypertrophic cardiomyopathy. | Serum cardiac troponin I (cTnI) is a sensitive and specific marker of myocardial injury. However, a systematic evaluation of cTnI in hypertrophic cardiomyopathy (HCM) patients has not been performed.</AbstractText>The purpose of this study is to evaluate cTnI and determine its relationship to clinical features in HCM.</AbstractText>We studied serum cTnI in 162 consecutive HCM patients.</AbstractText>Serum cTnI ranged from 0.01 to 0.83 ng/mL (mean, 0.068 +/- 0.100 ng/mL) and was higher in male patients (P < .001), those with atrial fibrillation (P = .033), and left ventricular (LV) systolic dysfunction (P = .046). Serum cTnI values were also correlated with maximum LV wall thickness (r = 0.30, P < .001), LV end-systolic diameter (r = 0.20, P = .012), and E/Ea (peak early transmitral filling velocity/early diastolic mitral annulus velocity; r = 0.24, P = .004). Serum cTnI levels were not significantly different among New York Heart Association (NYHA) functional class and there was no difference between patients with or without LV outflow tract obstruction; although B-type natriuretic peptide (BNP) levels showed significant difference in those variables. Serum cTnI had very weak correlation with BNP values (r = 0.18, P = .023). Multivariate analysis revealed an independent relationship between cTnI and maximum LV wall thickness, E/Ea, and male gender.</AbstractText>In patients with HCM, serum cTnI was associated with important clinical indices such as maximum LV wall thickness, LV dysfunction, and male gender. Serum cTnI seemed to have clinical significance different from that of BNP and may not be reflecting cardiac load but the LV remodeling process in HCM.</AbstractText>Copyright 2010 Wiley Periodicals, Inc.</CopyrightInformation> |
6,009 | Defibrillation delivered during the upstroke phase of manual chest compression improves shock success. | The current standard of manual chest compression during cardiopulmonary resuscitation requires pauses for rhythm analysis and shock delivery. However, interruptions of chest compression greatly decrease the likelihood of successful defibrillations, and significantly better outcomes are reported if this interruption is avoided. We therefore undertook a prospective randomized controlled animal study in an electrically induced ventricular fibrillation pig model to assess the effects of timing of defibrillation on the manual chest compression cycle on the defibrillation threshold.</AbstractText>Prospective, randomized, controlled animal study.</AbstractText>University-affiliated research laboratory.</AbstractText>Yorkshire-X domestic pigs (Sus scrofa).</AbstractText>In eight domestic male pigs weighing between 24 and 31 kg, ventricular fibrillation was electrically induced and untreated for 10 secs. Manual chest compression was then performed and continued for 25 secs with the protection of an isolation blanket. The depth and frequency of chest compressions were guided by a cardiopulmonary resuscitation prompter. Animals were randomized to receive a biphasic electrical shock in five different compression phases with a predetermined energy setting. A control phase was chosen at a constant 2 secs after discontinued chest compression. A grouped up-down defibrillation threshold testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 mins, the sequence was repeated for a total of 60 test shocks for each animal.</AbstractText>No difference in coronary perfusion pressure before delivering of the shock was observed among the six study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of manual chest compression.</AbstractText>Defibrillation efficacy is maximal when electrical shock is delivered during the upstroke phase of manual chest compression.</AbstractText> |
6,010 | Omega-3 fatty acid supplementation does not reduce risk of atrial fibrillation after coronary artery bypass surgery: a randomized, double-blind, placebo-controlled clinical trial. | Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been reported to reduce the risk of sudden cardiac death presumed to be due to fatal ventricular arrhythmias, but their effect on atrial arrhythmias is unclear.</AbstractText>Patients (n=108) undergoing coronary artery bypass graft surgery were randomly assigned to receive 2 g/d n-3 PUFA or placebo (olive oil) for at least 5 days before surgery (median, 16 days; range, 12 to 21 days). Phospholipid n-3 PUFA were measured in serum at study entry and at surgery and in right atrial appendage tissue at surgery. Echocardiography was used to assess left ventricular function and left atrial dimensions. Postoperative continuous ECG monitoring (Lifecard CF) for 5 days or until discharge, if earlier, was performed with a daily 12-lead ECG and clinical review if patients remained in the hospital beyond 5 days. Lifecard recordings were analyzed for episodes of atrial fibrillation (AF) > or =30 seconds (primary outcome). Clinical AF, AF burden (% time in AF), hospital stay, and intensive care/high dependency care stay were measured as secondary outcomes. One hundred three patients completed the study (51 in the placebo group and 52 in the n-3 PUFA group). There were no clinically relevant differences in baseline characteristics between groups. n-3 PUFA levels were higher in serum and right atrial tissue in the active treatment group. There was no significant difference between groups in the primary outcome of AF (95% confidence interval [CI], -6% to 30%, P=0.28) in any of the secondary outcomes or in AF-free survival.</AbstractText>Omega-3 PUFA do not reduce the risk of AF after coronary artery bypass graft surgery. Clinical Trial Registration- www.ukcrn.org.uk. Identifier: 4437.</AbstractText> |
6,011 | Chest compressions cause recurrence of ventricular fibrillation after the first successful conversion by defibrillation in out-of-hospital cardiac arrest. | Unlike Resuscitation Guidelines (GL) 2000, GL2005 advise resuming cardiopulmonary resuscitation (CPR) immediately after defibrillation. We hypothesized that immediate CPR resumption promotes earlier recurrence of ventricular fibrillation (VF).</AbstractText>This study used data of a prospective per-patient randomized controlled trial. Automated external defibrillators used by first responders were randomized to either (1) perform postshock analysis and prompt rescuers to a pulse check (GL2000), or (2) resume CPR immediately after defibrillation (GL2005). Continuous recordings of ECG and impedance signals were collected from all patients with an out-of-hospital cardiac arrest to whom a randomized automated external defibrillator was applied. We included patients with VF as their initial rhythm in whom CPR onset could be determined from the ECG and impedance signals. Time intervals are presented as median (Q1-to-Q3). Of 361 patients, 136 met the inclusion criteria: 68 were randomly assigned to GL2000 and 68 to GL2005. Rescuers resumed CPR 30 (21-to-39) and 8 (7-to-9) seconds, respectively, after the first shock that successfully terminated VF (P<0.001); VF recurred after 40 (21-to-76) and 21 (10-to-80) seconds, respectively (P=0.001). The time interval between start of CPR and VF recurrence was 6 (0-to-67) and 8 (3-to-61) seconds, respectively (P=0.88). The hazard ratio for VF recurrence in the first 2 seconds of CPR was 15.5 (95% confidence interval, 5.63 to 57.7) compared with before CPR resumption. After more than 8 seconds of CPR, the hazard of VF recurrence was similar to before CPR resumption.</AbstractText>Early CPR resumption after defibrillation causes early VF recurrence. Clinical Trial Registration- clinicaltrials.gov Identifier: ISRCTN72257677.</AbstractText> |
6,012 | Loss-of-function mutation of the SCN3B-encoded sodium channel {beta}3 subunit associated with a case of idiopathic ventricular fibrillation. | Loss-of-function mutations in the SCN5A-encoded sodium channel SCN5A or Nav1.5 have been identified in idiopathic ventricular fibrillation (IVF) in the absence of Brugada syndrome phenotype. Nav1.5 is regulated by four sodium channel auxiliary beta subunits. Here, we report a case with IVF and a novel mutation in the SCN3B-encoded sodium channel beta subunit Navbeta3 that causes a loss of function of Nav1.5 channels in vitro.</AbstractText>Comprehensive open reading frame mutational analysis of KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, GPD1L, four sodium channel beta subunit genes (SCN1-4B), and targeted scan of RYR2 was performed. A novel missense mutation, Navbeta3-V54G, was identified in a 20-year-old male following witnessed collapse and defibrillation from VF. The ECG exhibited epsilon waves, and imaging studies demonstrated a structurally normal heart. The mutated residue was highly conserved across species, localized to the Navbeta3 extracellular domain, and absent in 800 reference alleles. We found that HEK-293 cells had endogenous Navbeta3, but COS cells did not. Co-expression of Nav1.5 with Navbeta3-V54G (with or without co-expression of the Navbeta1 subunit) in both HEK-293 cells and COS cells revealed a significant decrease in peak sodium current and a positive shift of inactivation compared with WT. Co-immunoprecipitation experiments showed association of Navbeta3 with Nav1.5, and immunocytochemistry demonstrated a dramatic decrease in trafficking to the plasma membrane when co-expressed with mutant Navbeta3-V54G.</AbstractText>This study provides molecular and cellular evidence implicating mutations in Navbeta3 as a cause of IVF.</AbstractText> |
6,013 | Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols. | Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction.</AbstractText>Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed.</AbstractText>SS_SSFP had significantly better quality scores in all categories (P = 0.037, P = 0.014, P = 0.021, P = 0.03). SNR(infarct) and SNR(blood) were significantly better for IR_FGRE than for SS_SSFP (P = 0.048, P = 0.018). No significant difference was found in SNR(myocardium) and CNR. The myocardial volume was significantly larger with SS_SSFP (170.7 versus 159.2 ml, P<0.001), but no significant difference was found in infarct volume and infarct extent.</AbstractText>SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.</AbstractText> |
6,014 | Diastolic heart failure: a clinical challenge early recognition & timely intervention is the need of the hour. | Diastolic Heart failure (DHF) is the major cause of morbidity and mortality all over the world. It is responsible for more than 50% of the heart failure cases. New onset of symptomatic DHF is a lethal disease with a 5-yr mortality of approximately 50%. DHF is also referred to as heart failure (HF) with normal left ventricular ejection fraction (LVEF)-HFNLVEF. The diagnosis of DHF requires the following criteria: (i) signs and symptoms of heart failure (ii) normal or mildly abnormal systolic left ventricular (LV) function (iii) evidence of LV diastolic dysfunction. Diagnostic evidence of LV diastolic dysfunction can be obtained invasively (LV end-diastolic pressure > 16 mmHg or mean pulmonary capillary wedge pressure > 12 mmHg) or non-invasively by tissue Doppler imaging (TDI) (E/E' > 15). If TDI yields an E/E' ratio suggestive of LV diastolic dysfunction (15 > E/E' > 8), then additional echo variables are required for diagnostic evidence of LV diastolic dysfunction, which include Doppler flow profile of mitral valve or pulmonary veins, measurement of LV mass index (LVMi) or left atrium volume index (LAVi), electrocardiographic evidence of atrial fibrillation or high levels of B-natreuretic peptide. Echo-Doppler techniques using LV filling pressures and tissue Doppler imaging of the mitral annulus help in identifying and classifying the degree of LV diastolic dysfunction. However, clinically this is more relevant to advanced overt disease. Therefore early recognition of DHF in relatively asymptomatic or less symptomatic patients with occult LV diastolic dysfunction is a real challenge. Recently it has been shown that reduction in left atrial strain and strain rate and increase in left atrial (LA) stiffness index has a high predictive value for detection of occult LV diastolic dysfunction. Thus early recognition of occult DHF and timely therapeutic intervention may help in prognostic stratification in DHF. |
6,015 | Excision of native heart and relocation of a grown heterotopic donor heart to the orthotopic position 14 years after transplantation. | Here we report the treatment of native heart complications (aortic regurgitation, ventricular fibrillation and heart failure) following a heterotopic heart transplant by excision of native heart and relocation the heterotopic heart in the orthotopic position. The patient was a 24 year old woman who had received a heterotopic transplant at the age of 9 years from a 9 year old donor. The donor heart had grown sufficiently to allow it to support her adult circulation. |
6,016 | Early repolarization in young children with attention-deficit/hyperactivity disorder versus normal controls: a retrospective preliminary chart review study. | Early repolarization (ER), considered a common and benign electrocardiographic pattern on the surface 12-lead electrocardiogram (ECG), was recently found to be prevalent among patients with idiopathic ventricular fibrillation. It is also highly predominant in physically active young males. Reports on sudden cardiac death (SCD) of children and adolescents treated with psychotropic agents have raised concerns regarding the need for cardiovascular monitoring and risk stratification schedules. The rate of ER pattern has not been estimated in children with attention deficit/hyperactivity disorder (ADHD). Thus, in the present retrospective chart review study, we estimated the rate of ER pattern, as well as RR, QT, and QTc intervals, from ECG tracings of physically healthy children with ADHD versus physically and mentally healthy controls.</AbstractText>The ECG tracings of 50 children (aged 8.7 +/- 1.4 years; 12 girls, 44 boys) diagnosed as suffering from ADHD were compared to 55 physically and mentally healthy controls (aged 8.25 +/- 2.1 years; 20 girls, 35 boys). ER was defined as an elevation of the QRS-ST junction (J point) of at least 0.1 mV from baseline with slurring or notching of the QRS complex, and assessed separately by two senior cardiologists who were blind to all other data relating to the study participants.</AbstractText>The rate of ER pattern was significantly higher in ADHD children compared to normal controls (32% vs. 13%, respectively, P = 0.012; relative risk [RR] = 1.68, 95% confidence interval [CI] 1.16-2.44), irrespective of stimulant treatment or gender. All other standard ECG measures (heart rate, QT and QTc intervals) were within normal range.</AbstractText>The rate of ER in children with ADHD is significantly higher than in normal controls. Its clinical significance awaits further research.</AbstractText> |
6,017 | Interassay reproducibility of myocardial perfusion gated SPECT in patients with atrial fibrillation. | The aim of this study was to assess interassay reproducibility of myocardial perfusion gated-SPECT for calculation of end-diastolic volume (EDV), end-systolic volume (ESV), and left ventricular ejection fraction (LVEF) in patients with atrial fibrillation (AF).</AbstractText>One hundred and fifteen consecutive patients with AF from three participating hospitals (mean age 68.9 years, 39 women) were included in the study. All patients underwent two image gated acquisitions at rest with a 30 minute interval between them. Quantitative data were obtained using the QGS and ECT software algorithms.</AbstractText>Heart rate was similar in both studies: 74.94 +/- 15.2 vs 73.03 +/- 15.57. QGS yielded an LVEF of 54.4%/53.8%, an EDV of 100 mL/101.5 mL, and an ESV of 51 mL/52.3 mL; and ECT showed an LVEF of 63.6%/62.9%, an EDV of 125.8 mL/127.4 mL and ESV of 54.1 mL/56.3 mL. Correlation between the two acquisitions was high (>0.948) for both methods for LVEF, EDV and ESV. Regression and Bland-Altman graphics showed a good agreement between all parameters. Interassay variation coefficients for each method (QGS/ECT) were 5.29% vs 4.83% for LVEF, 4.94% vs 5.17% for EDV, and 9.94% vs 12.78% for ESV.</AbstractText>Interassay reproducibility of LVEF and EDV with gated-SPECT in patients with AF is good, whereas for ESV it is suboptimal, particularly when ESV is small.</AbstractText> |
6,018 | Human K(ATP) channelopathies: diseases of metabolic homeostasis. | Assembly of an inward rectifier K+ channel pore (Kir6.1/Kir6.2) and an adenosine triphosphate (ATP)-binding regulatory subunit (SUR1/SUR2A/SUR2B) forms ATP-sensitive K+ (KATP) channel heteromultimers, widely distributed in metabolically active tissues throughout the body. KATP channels are metabolism-gated biosensors functioning as molecular rheostats that adjust membrane potential-dependent functions to match cellular energetic demands. Vital in the adaptive response to (patho)physiological stress, KATP channels serve a homeostatic role ranging from glucose regulation to cardioprotection. Accordingly, genetic variation in KATP channel subunits has been linked to the etiology of life-threatening human diseases. In particular, pathogenic mutations in KATP channels have been identified in insulin secretion disorders, namely, congenital hyperinsulinism and neonatal diabetes. Moreover, KATP channel defects underlie the triad of developmental delay, epilepsy, and neonatal diabetes (DEND syndrome). KATP channelopathies implicated in patients with mechanical and/or electrical heart disease include dilated cardiomyopathy (with ventricular arrhythmia; CMD1O) and adrenergic atrial fibrillation. A common Kir6.2 E23K polymorphism has been associated with late-onset diabetes and as a risk factor for maladaptive cardiac remodeling in the community-at-large and abnormal cardiopulmonary exercise stress performance in patients with heart failure. The overall mutation frequency within KATP channel genes and the spectrum of genotype-phenotype relationships remain to be established, while predicting consequences of a deficit in channel function is becoming increasingly feasible through systems biology approaches. Thus, advances in molecular medicine in the emerging field of human KATP channelopathies offer new opportunities for targeted individualized screening, early diagnosis, and tailored therapy. |
6,019 | Cost-effectiveness of therapeutic hypothermia after cardiac arrest. | Therapeutic hypothermia can improve survival and neurological outcomes in cardiac arrest survivors, but its cost-effectiveness is uncertain. We sought to evaluate the cost-effectiveness of treating comatose cardiac arrest survivors with therapeutic hypothermia.</AbstractText>A decision model was developed to capture costs and outcomes for patients with witnessed out-of-hospital ventricular fibrillation arrest who received conventional care or therapeutic hypothermia. The Hypothermia After Cardiac Arrest (HACA) trial inclusion criteria were assumed. Model inputs were determined from published data, cooling device companies, and consultation with resuscitation experts. Sensitivity analyses and Monte Carlo simulations were performed to identify influential variables and uncertainty in cost-effectiveness estimates. The main outcome measures were quality-adjusted survival after cardiac arrest, cost of hypothermia implementation, cost of posthospital discharge care, and incremental cost-effectiveness ratios. In our model, postarrest patients receiving therapeutic hypothermia gained an average of 0.66 quality-adjusted life years compared with conventional care, at an incremental cost of $31,254. This yielded an incremental cost-effectiveness ratio of $47,168 per quality-adjusted life year. Sensitivity analyses demonstrated that poor neurological outcome postcooling and costs associated with posthypothermia care (in-hospital and long term) were the most influential variables in the model. Even at extreme estimates for costs, the cost-effectiveness of hypothermia remained less than $100,000 per quality-adjusted life year. In 91% of 10,000 Monte Carlo simulations, the incremental cost-effectiveness ratio was less than $100,000 per quality-adjusted life year.</AbstractText>In cardiac arrest survivors who meet HACA criteria, therapeutic hypothermia with a cooling blanket improves clinical outcomes with cost-effectiveness that is comparable to many economically acceptable health care interventions in the United States.</AbstractText> |
6,020 | Percutaneous closure of atrial septal defects: echocardiographic and functional results in patients older than 60 years. | Percutaneous closure of atrial septal defects is well established in children and adults and has been found to improve symptoms and positively influence right-heart remodeling. The aim of this study was to evaluate the efficacy and long-term outcome in adult patients older than 60 years.</AbstractText>The study population comprised 96 patients in the age group of 60 to 84 years. Percutaneous closure was performed effectively in all patients. Functional capacity according to New York Heart Association functional class and peak oxygen uptake (VO(2)max) in the cardiopulmonary exercise testing improved significantly after atrial septal defects closure, especially in patients with a pulmonary-to-systemic flow ratio >2. Echocardiographic measurements of the right ventricular end-diastolic diameter showed a significant decrease. No device-associated complications were observed, but in 16 patients, paroxysmal atrial fibrillation occurred after device implantation.</AbstractText>Percutaneous atrial septal defects closure can be performed safely and with minimal risk even in elderly patients. They profit in terms of symptom reduction, improvement of exercise capacity, and right-heart remodeling.</AbstractText> |
6,021 | Differences in pharmacology and their translation into differences in clinical efficacy--a comparison of the renin angiotensin blocking agents irbesartan and losartan. | Guidelines recommend five antihypertensive drug classes, but which particular drug to choose is up to the treating physician. We aimed at an in-depth comparison of two frequently used angiotensin receptor blockers to provide evidence for this decision.</AbstractText>Pharmacology of irbesartan and losartan, their blood-pressure-lowering efficacy, their tolerability/safety, end-organ protective effects and economic evaluation.</AbstractText>Both drugs differ in their oral bioavailability, potential for food interactions, degree of metabolism, dosing interval, time to peak, volume of distribution and terminal half-life. Irbesartan provides a greater and longer-lasting antihypertensive effect and was determined to be cost effective over losartan in Denmark and Sweden. Irbesartan was more effective in preventing deterioration of kidney function in patients with diabetic nephropathy, being cost effective from a German perspective. There is only one end point trial for either drug in patients with left ventricular hypertrophy, heart failure and atrial fibrillation, but no direct comparison.</AbstractText>There is an incremental clinical benefit of irbesartan over losartan in the treatment of hypertension and diabetic nephropathy which can be substantiated by corresponding preclinical study evidence. This has translated into an economic benefit in a number of country-specific evaluations.</AbstractText> |
6,022 | Myocardial Ca2+ handling and cell-to-cell coupling, key factors in prevention of sudden cardiac death. | Using whole-heart preparations, we tested our hypothesis that Ca(2+) handling is closely related to cell-to-cell coupling at the gap junctions and that both are critical for the development and particularly the termination of ventricular fibrillation (VF) and hence the prevention of sudden arrhythmic death. Intracellular free calcium concentration ([Ca(2+)](i)), ECG, and left ventricular pressure were continuously monitored in isolated guinea pig hearts before and during development of low K(+)-induced sustained VF and during its conversion into sinus rhythm facilitated by stobadine. We also examined myocardial ultrastructure to detect cell-to-cell coupling alterations. We demonstrated that VF occurrence was preceded by a 55.9% +/- 6.2% increase in diastolic [Ca(2+)](i), which was associated with subcellular alterations indicating Ca(2+) overload of the cardiomyocytes and disorders in coupling among the cells. Moreover, VF itself further increased [Ca(2+)](i) by 58.2% +/- 3.4% and deteriorated subcellular and cell-to-cell coupling abnormalities that were heterogeneously distributed throughout the myocardium. In contrast, termination of VF and its conversion into sinus rhythm was marked by restoration of basal [Ca(2+)](i), resulting in recovery of intercellular coupling linked with synchronous contraction. Furthermore, we have shown that hearts exhibiting lower SERCA2a (sarcoplasmic reticulum Ca(2+)-ATPase) activity and abnormal intercellular coupling (as in older guinea pigs) are more prone to develop Ca(2+) overload associated with cell-to-cell uncoupling than hearts with higher SERCA2a activity (as in young guinea pigs). Consequently, young animals are better able to terminate VF spontaneously. These findings indicate the crucial role of Ca(2+) handling in relation to cell-to-cell coupling in both the occurrence and termination of malignant arrhythmia. |
6,023 | Sustained manual abdominal compression during cardiopulmonary resuscitation in a pig model: a preliminary investigation. | The present study was undertaken to determine whether sustained manual abdominal compression (SMAC) using left paramedian compression technique can improve coronary perfusion pressure (CPP) during cardiopulmonary resuscitation (CPR) and resuscitation outcomes without causing liver laceration.</AbstractText>Ventricular fibrillation was induced in 14 pigs, and circulatory arrest was maintained for 6 min. Animals were resuscitated either by standard CPR (control group) or by standard CPR with SMAC (SMAC-CPR group).</AbstractText>Mean blood pressure, aortic diastolic pressure and right atrial diastolic pressure in the SMAC-CPR group were significantly greater than in the control group throughout simulated basic life support. However, since the increases in aortic and right atrial diastolic pressures were similar, no significant intergroup difference was found in terms of CPP. Return of spontaneous circulation (ROSC) was attained in four of seven animals in the control group and in six of seven animals in the SMAC-CPR group (p = 0.55). Three animals in the control group and four in the SMAC-CPR group survived 24 h after ROSC (p = 1.00). Two of the seven animals in the SMAC-CPR group had a ruptured liver, but no such injury occurred in the control group.</AbstractText>SMAC using left paramedian compression technique failed to improve CPP during CPR and resuscitation outcomes. Furthermore, this method could not avoid liver laceration.</AbstractText> |
6,024 | A rectangular dermatosis of the left back. | Cardioversion and defibrillation have become widely used techniques aimed at restoring normal sinus rhythm in patients with cardiac arrhythmias. Following the procedure, cutaneous lesions are often seen at the site of the electrodes, but little has been reported regarding the evolution of such lesions over time.</AbstractText>Two patients presented with unusual, well-defined rectangular eruptions on the left back, and both reported a history of having undergone electrical cardioversion or defibrillation several years previously. The histologic characteristics of each lesion were distinct, and the management was symptomatic, with most of the relief coming from the recognition that the eruption was actually a self-limited manifestation of cardioversion and defibrillation.</AbstractText>The clinical cases and corresponding histologic findings represent possible long-term sequelae of electrical cardioversion or defibrillation. They are presented in order to enhance the diagnostic acumen of dermatologists and to avoid potential misdiagnosis.</AbstractText> |
6,025 | Frequent recurrent polymorphic ventricular tachycardia during sleep due to managed ventricular pacing. | We report a case of a patient with an implantable cardioverter defibrillator and no prior history of heart block with managed ventricular pacing (MVP) programmed who had frequent recurrent episodes of polymorphic ventricular tachycardia. All of the episodes were initiated by transient atrioventricular block which resulted in short-long-short sequences permitted by MVP. This case illustrates that MVP should be used with caution not only in patients with complete heart block, but also in patients at risk for brief heart block due to such states as hypervagatonia due to sleep apnea. |
6,026 | Variability of left ventricular electromechanical activation during right ventricular pacing: implications for the selection of the optimal pacing site. | The right ventricular septum (RVS) and Hisian area (HA) are considered more "physiological" pacing sites than right ventricular apex (RVA). Studies comparing RVS to RVA sites have produced controversial results. There are no data about variability of electromechanical activation obtained by an approach using fluoroscopy and electrophysiological markers. This study compared the variability of left ventricular (LV) electromechanical activation in patients undergoing short-term RVA and RVS with that measured during HA pacing based on fluoroscopy and electrophysiological markers.</AbstractText>Tissue Doppler echocardiography was performed in 142 patients before and after RVA (54), RVS (44), and HA (44) pacing. Electromechanical activation was assessed by: (1) electromechanical latency (EML)-interval between QRS onset and mechanical activation of basal LV; (2) intra-LV dyssynchrony (intra-LV)-interval between earliest to the latest LV basal motion. The intra- and interpatients variability among pacing groups were assessed.</AbstractText>Pacing from RVA showed longer EML and higher degree of intra-LV than RVS and HA pacing. RVA and RVS showed a higher variability than HA pacing with regard to intrapatient changes of EML (RVA vs RVS, P = 0.4; RVS vs HA, P = 0.01, RVA vs HA, P = 0.0002) and intra-LV (RVA vs RVS, P = 0.2; RVS vs HA, P = 0.04; RVA vs HA, P = 0.005). Similar results were found in interpatients variability from paced-values.</AbstractText>RVA and RVS pacing produce a variable effect on LV electromechanical activation that is significantly more pronounced than HA pacing. A pacing site such as HA selected by fluoroscopic and electrophysiological markers maintains baseline and homogeneous LV activation pattern.</AbstractText> |
6,027 | Heart failure registry: a valuable tool for improving the management of patients with heart failure. | Guidelines on how to diagnose and treat patients with heart failure (HF) are published regularly. However, many patients do not fulfil the diagnostic criteria and are not treated with recommended drugs. The Swedish Heart Failure Registry (S-HFR) is an instrument which may help to optimize the handling of HF patients.</AbstractText>The S-HFR is an Internet-based registry in which participating centres (units) can record details of their HF patients directly online and transfer data from standardized forms or from computerized patient documentation. Up to December 2007, 16,117 patients from 78 units had been included in the S-HFR. Of these, 10,229 patients had been followed for at least 1 year, and 2133 deaths were recorded. Online reports from the registry showed that electrocardiograms were available for 97% of the patients. Sinus rhythm was found in 51% of patients and atrial fibrillation in 38%. Echocardiography was performed in 83% of the patients. Overall, 77% of patients were treated with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers, 80% were on beta-blockers, 34% on aldosterone antagonists, and 83% on diuretics.</AbstractText>The S-HFR is a valuable tool for improving the management of patients with HF, since it enables participating centres to focus on their own potential for improving diagnoses and medical treatment, through the online reports provided.</AbstractText> |
6,028 | Will simultaneous measurement of E/e' index facilitate the non-invasive assessment of left ventricular filling pressure in patients with non-valvular atrial fibrillation? | The ratio of early transmitral flow velocity (E) to early diastolic mitral annular velocity (e') was applied as a non-invasive index to assess left ventricular filling pressure (LVFP). However, the reliability of E/e' was undermined in patients with atrial fibrillation (AF). Recently, a novel method entitled 'dual Doppler' was established, which allows simultaneous recording and display of E and e'. Our study investigates whether the dual-Doppler method improves the reliability of E/e' in AF patients.</AbstractText>Forty-nine patients with non-valvular AF underwent conventional echocardiography, dual-Doppler echocardiography, and cardiac catheterization within 4 h. Of 22 patients (45%c) with increased LVFP (>15 mmHg), higher E/e' measured by both conventional tissue Doppler imaging (TDI) and dual-Doppler method was observed. Conventional echocardiographic variables were correlated with LVFP (E/e'(sep), r = 0.404, E/e'(lat), r = 0.487), but E/e' measured synchronously in the dual-Doppler mode yielded a better correlation (E/e'(synchronous sep), r = 0.754, E/e'(synchronous lat), r = 0.765). The intra- and interobserver variability of the dual-Doppler method was significantly lower than the conventional TDI method.</AbstractText>Good correlations were found between E/e'' and LVFP in patients with AF, particularly in the dual-Doppler mode. E/e' measured by the dual-Doppler method can therefore be applied to assess diastolic dysfunction in AF patients.</AbstractText> |
6,029 | Delaying a shock after takeover from the automated external defibrillator by paramedics is associated with decreased survival. | The purpose of this study was to investigate whether the takeover by Advanced Life Support [ALS] trained ambulance paramedics from rescuers using an automated external defibrillator [AED] delays shocks and if this delay is associated with decreased survival after out-of-hospital cardiac arrest [OHCA].</AbstractText>We analyzed continuous ECG recordings of LIFEPAK AEDs and associated manual defibrillator recordings of OHCA of presumed cardiac cause, prospectively collected from July 2005 to July 2009. The primary outcome measure was survival to discharge. Among 693 patients treated with AEDs, 110 had a shockable initial rhythm and a shockable rhythm during ALS takeover. We measured the time interval between the expected shock if the AED would remain attached to the patient and the first observed shock given by the manual defibrillator [shock timing].</AbstractText>Survival was 62% (13/21) if the shock was given early (<-20s), 52% (11/21; odds ratio [OR]=0.68, ns) if given on time (-20 to 20s), 29% (10/34; OR=0.26, 95% confidence interval [CI]=0.08-0.81; P=0.02) if the shock was 20-150s delayed and 21% (7/34; OR=0.16, 95% CI=0.05-0.54; P=0.003) if the shock was delayed >150s. The OR for trend was 0.41, 95% CI=0.25-0.71; P=0.001. The association between shock timing and survival was significant for patients with more than 150s shock delay (OR=0.19; 95% CI=0.04-0.71; P=0.02) or for trend in shock timing (0.42, 95% CI=0.20-0.84; P=0.02) after multivariable adjustment for prognostic factors age and slope of ventricular fibrillation.</AbstractText>ALS takeover delays the next shock delivery in almost two-third of cases. This delay is associated with decreased survival.</AbstractText>Copyright 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,030 | Plasma CA-125 level is related to both sides of the heart: a retrospective analysis. | CA-125 is an old marker, recently shown to be associated with systolic heart failure. We aimed to search for factors influencing its plasma level.</AbstractText>430 patients with one available CA-125 level were investigated retrospectively. 150 patients who had echocardiographic records were enrolled into final analysis. Patients were followed up, hospitalization and mortality were noted.</AbstractText>CA-125 levels were negatively correlated with ejection fraction (r=-0.269, p=0.001) and positively correlated with systolic pulmonary artery pressure (r=0.370, p<0.001). In the whole group, patients with right ventricular dilatation (n=68) had significantly higher CA-125 levels compared to those without right ventricular dilatation (n=82) (125.8±118.4 U/ml vs.16.9±16.5 U/ml, p<0.001). Presence of depressed ejection fraction (B=1.837, p=0.004), presence of right ventricular dilatation (B=4.294, p=0.002) and presence of pericardial effusion (B=1.913, p=0.018) were independent predictors of high CA-125 levels. After follow up, patients with high CA-125 level encountered more frequent hospitalization and mortality, and atrial fibrillation was more frequent among those with high CA-125.</AbstractText>Our data suggests that plasma levels of CA-125 seem to be determined by left ventricular ejection fraction, right ventricular dilatation and presence of pericardial effusion in a group of all comers. It seems prudent to consider these factors before integrating CA-125 into clinical practice.</AbstractText>Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,031 | Is concomitant surgery for moderate functional mitral regurgitation indicated during aortic valve replacement for aortic stenosis? A systematic review and evidence-based recommendations. | Mitral regurgitation (MR) is associated with poor clinical outcomes. Functional MR is often associated with aortic stenosis (AS) and may resolve after aortic valve replacement (AVR). The objective of this study was to derive evidence-based recommendations regarding surgical intervention for moderate functional MR at the time of AVR for AS.</AbstractText>An exhaustive literature search strategy including Medline, Embase, the Cochrane library, and meeting abstracts was performed. Studies meeting inclusion criteria were critically appraised and data pooled according to accepted meta-analysis techniques. The primary outcome was change in moderate MR after isolated AVR. Secondary outcomes were the impact of functional MR on survival and identifying factors that predict progression of MR, in patients undergoing isolated AVR for AS.</AbstractText>Thirteen nonrandomized studies including 2113 patients were reviewed. A total of 268 patients had preoperative moderate functional MR and AS. All studies were appraised as poor methodological quality. After isolated AVR a trend toward improvement in MR was observed. Left ventricular dysfunction, left atrial enlargement, and atrial fibrillation were associated with progression of MR after AVR. However, the impact of residual MR on late survival was not consistent.</AbstractText>Pooling current evidence provided inconclusive evidence to make clinical practice recommendations for or against routine surgical intervention of moderate MR at the time of AVR for AS. The incidence of this pathology makes further clinical trial studies warranted.</AbstractText> |
6,032 | Prevalence of the Brugada-type electrocardiogram and incidence of Brugada syndrome in patients with sick sinus syndrome. | In the present study, clarification of the prevalence of the Brugada-type electrocardiogram (ECG) and the incidence of spontaneous ventricular fibrillation (VF) that occurred with the Brugada-type ECG in patients with sick sinus syndrome (SSS) was determined.</AbstractText>A total of 487 consecutive patients (men 45%, mean age 69.9+/-12.3 years), who were defined as having an indication for cardiac pacemaker (PM) for SSS, were investigated. The ECG before an initial PM implantation and occurrence of VF or sudden cardiac death (SCD) was examined retrospectively. Brugada-type ECG was found in 14 patients (2.87%) including 4 (0.82%) with type 1 and 10 (2.05%) with type 2. During the follow-up period of 7.2+/-5.4 years, 2 out of the 4 patients with type 1 ECG had experienced a VF episode after the device implantation. In 10 patients with type 2 ECG, none had VF or SCD. The incidence of spontaneous VF (Brugada syndrome) in SSS patients was calculated as 14.1 per 100 person-years with type 1 ECG.</AbstractText>The prevalence of typical Brugada-type (type 1) ECG in SSS patients seems to be higher compared with the general population. In addition, SSS patients with the typical Brugada-type ECG might be a high risk for spontaneous VF.</AbstractText> |
6,033 | Heart rhythm at the time of death documented by an implantable loop recorder. | The aims of this study were to describe arrhythmias documented with an implantable loop recorder (ILR) in post-acute myocardial infarction (AMI) patients with left ventricular dysfunction at the time of death and to establish the correlation to mode of death.</AbstractText>Post-mortem ILR device interrogations were analysed from patients dying in the CARISMA study. Mode of death was classified by a modified CAST classification. Twenty-six patients died with an implanted ILR. Of these, 16 had an electrocardiogram recorded at the time of death. Ventricular tachycardia (VT)/ventricular fibrillation (VF) was terminal rhythm in eight patients and bradyarrhythmias were observed in another eight patients. Of the deaths with peri-mortem recordings, seven were classified as sudden cardiac death (SCD). In six of these, VF was documented at the time of death. Six monitored deaths were classified as non-SCD (NSCD) of which only two had recordings of VT/VF, whereas four had bradyarrhythmias. All peri-mortem recordings in non-cardiac death (NCD) were bradyarrhythmia.</AbstractText>Long-term monitoring in a population of post-AMI patients with left ventricular ejection fraction < or =40% showed that VT/VF and bradyarrhythmia each accounted for half of the recorded events at the time of death. The ILR confirmed that ventricular tachyarrhythmias are associated primarily with SCD, whereas bradyarrhythmias and electromechanical dissociation seems dominant in NSCD and NCD. The study was registered at ClinicalTrials.gov: NCT00145119.</AbstractText> |
6,034 | Significance of cardiac sympathetic nervous system abnormality for predicting vascular events in patients with idiopathic paroxysmal atrial fibrillation. | Neuronal system activity plays an important role for the prognosis of patients with atrial fibrillation (AF). Using (123)I metaiodobenzylguanidine ((123)I-MIBG) scintigraphy, we investigated whether a cardiac sympathetic nervous system (SNS) abnormality would be associated with an increased risk of vascular events in patients with paroxysmal AF.</AbstractText>(123)I-MIBG scintigraphy was performed in 69 consecutive patients (67 + or - 13 years, 62% men) with paroxysmal AF who did not have structural heart disease. SNS integrity was assessed from the heart to mediastinum (H/M) ratio on delayed imaging. Serum concentration of C-reactive protein (CRP) was measured before (123)I-MIBG study.</AbstractText>During a mean of 4.5 + or - 3.6 years follow-up, 19 patients had myocardial infarction, stroke or heart failure (range: 0.2-11.5 years). SNS abnormality (H/M ratio <2.7) and high CRP (> or = 0.3 mg/dl) were associated with the vascular events (58.3% in 14 of 24 patients with SNS abnormality vs 11.1% in 5 of 45 patients without SNS abnormality, p < 0.0001, 52.4% in 11 of 21 patients with high CRP vs 16.7% in 8 of 48 patients without high CRP, p < 0.0001). After adjustment for potential confounding variables such as age, left atrial dimension and left ventricular function, SNS abnormality was an independent predictor of vascular events with a hazard ratio of 4.1 [95% confidence interval (CI): 1.3-12.6, p = 0.014]. Further, SNS abnormality had an incremental and additive prognostic power in combination with high CRP with an adjusted hazard ratio of 4.1 (95% CI: 1.5-10.9, p = 0.006).</AbstractText>SNS abnormality is predictive of vascular events in patients with idiopathic paroxysmal AF.</AbstractText> |
6,035 | Termination of electrocution-induced ventricular fibrillation by an implantable cardioverter defibrillator. | We describe a case in which an implantable cardioverter defibrillator (ICD) saved a patient's life after he tried to commit suicide by electrocuting himself. Deaths caused by electrocution are usually accidental and rarely suicidal. The amount of current flow is the most important factor in deciding the degree of electrical injury, which may range from transient muscle tremors to death. The ICD is electrically insulated from surrounding electromagnetic interference and the passage of electric current typically does not damage or reprogram the device. In our patient, electromagnetic interference caused by the electric current initially triggered the noise reversion mode, leading to asynchronous pacing. Ventricular fibrillation was detected and terminated only after the electromagnetic interference stopped, as depicted by the intracardiac electrogram. This case is the first documented example of an ICD-aborted fatal electrocution from ventricular fibrillation caused by an unnatural electrical source. (PACE 2010; 510-512). |
6,036 | Imaging modalities in cardiac electrophysiology. | Cardiac imaging, both noninvasive and invasive, has become a crucial part of evaluating patients during the electrophysiology procedure experience. These anatomical data allow electrophysiologists to not only assess who is an appropriate candidate for each procedure, but also to determine the rate of success from these procedures. This article incorporates a review of the various cardiac imaging techniques available today, with a focus on atrial arrhythmias, ventricular arrhythmias and device therapy. |
6,037 | Serum N-terminal-pro-brain natriuretic peptide level and its clinical implications in patients with atrial fibrillation. | Brain natriuretic peptide (BNP) is increasingly being used for screening and monitoring of congestive heart failure. However, the role of BNP in patients with atrial fibrillation (AF) and normal left ventricular function has not been determined. This study investigates serum N-terminal pro-brain natriuretic peptide (NT-proBNP) level and its clinical implications in patients with AF.</AbstractText>Serum NT-proBNP levels were measured by enzyme-linked immunosorbent assay (ELISA) and transthoracic echocardiography was performed in 136 subjects (90 cases with AF and 46 cases with sinus rhythm [SR]). Subjects were excluded if they had a history of myocardial infarction, cardiomyopathy, rheumatic heart disease, or hyperthyroidism that preceded the onset of AF. Controls (n = 30) were from a healthy outpatient primary care population. Potential determinants of serum NT-proBNP levels were identified by univariate and multivariate analyses.</AbstractText>Individuals with AF had higher serum NT-proBNP levels (689.56 +/- 251.87 fmol/ml) than those with SR (456.11 +/- 148.14 fmol/ml, P < 0.01) and control subjects (415.83 +/- 62.02 fmol/ml, P < 0.01). Individuals with SR and control subjects did not show significant difference at serum NT-proBNP levels (P > 0.05). The regression model of serum NT-proBNP levels and clinical predictors showed that presence of AF, older age, and larger right atrial diameter were independently predictive of higher serum NT-proBNP values.</AbstractText>Patients with AF were associated with increased serum NT-proBNP levels. Examining the change of serum NT-proBNP levels is helpful to evaluate the cardiac function in patients with AF.</AbstractText>Copyright 2009 Wiley Periodicals, Inc.</CopyrightInformation> |
6,038 | Postoperative treatment of carvedilol following low dose landiolol has preventive effect for atrial fibrillation after coronary artery bypass grafting. | Postoperative atrial fibrillation (AF) is the most common complication after coronary artery bypass grafting (CABG). We have reported that the intra- and perioperative administration of landiolol has a preventive effect on postoperative AF in the early postoperative period after CABG surgery. The purpose of this study was to investigate the prophylactic effect of postoperative treatment with carvedilol following landiolol against postoperative AF.</AbstractText>We reviewed all patients who underwent CABG from December 2005 and February 2009. Fifty-three patients underwent scheduled isolated CABG and were divided two groups; carvedilol group (n = 31), and control group (n = 22). Incidences of postoperative AF were noted.</AbstractText>There was no statistical difference between the two groups with regard to the occurrence of AF after CABG. The maximum ventricular rate of AF was significantly lower in the carvedilol group than in the control group. All patients with AF in the control group needed treatment for tachycardia, but this was not necessary in the carvedilol group.</AbstractText>Postoperative treatment with carvedilol following landiolol has the effect of preventing tachycardia during AF after coronary artery bypass grafting.</AbstractText>Copyright Georg Thieme Verlag KG Stuttgart . New York.</CopyrightInformation> |
6,039 | Atrial fibrillation in congestive heart failure. | Atrial fibrillation (AF) and heart failure (HF) are common and interrelated conditions, each promoting the other, and both associated with increased mortality. HF leads to structural and electrical atrial remodeling, thus creating the basis for the development and perpetuation of AF; and AF may lead to hemodynamic deterioration and the development of tachycardia-mediated cardiomyopathy. Stroke prevention by antithrombotic therapy is crucial in patients with AF and HF. Of the 2 principal therapeutic strategies to treat AF, rate control and rhythm control, neither has been shown to be superior to the other in terms of survival, despite better survival in patients with sinus rhythm compared with those in AF. Antiarrhythmic drug toxicity and poor efficacy are concerns. Catheter ablation of AF can establish sinus rhythm without the risks of antiarrhythmic drug therapy, but has important procedural risks, and data from randomized trials showing a survival benefit of this treatment strategy are still lacking. In intractable cases, ablation of the atrioventricular junction and placement of a permanent pacemaker is a treatment alternative; and biventricular pacing may prevent or reduce the negative consequences of chronic right ventricular pacing. |
6,040 | Right atrial thrombosis after upgrading to a biventricular pacing/defibrillation system. | A 56-year-old man under right ventricular pacing for atrial fibrillation and bradycardia had congestive heart failure. He received a cardiac resynchronization pacemaker with a defibrillator. Four months later, follow-up transthoracic echocardiography showed a right atrial mass although he had no symptom. Transesophageal echocardiography showed a large immobile round-shaped mass on the defibrillation lead, which was attached to the free wall of the right atrium. One month after the initiation of anticoagulant therapy, the mass disappeared, suggesting that it was thrombotic. During the 5 month follow-up, he remained in good condition without the recurrence of right atrial thrombosis. |
6,041 | Cardiotoxicity of anticancer drugs: the need for cardio-oncology and cardio-oncological prevention. | Due to the aging of the populations of developed countries and a common occurrence of risk factors, it is increasingly probable that a patient may have both cancer and cardiovascular disease. In addition, cytotoxic agents and targeted therapies used to treat cancer, including classic chemotherapeutic agents, monoclonal antibodies that target tyrosine kinase receptors, small molecule tyrosine kinase inhibitors, and even antiangiogenic drugs and chemoprevention agents such as cyclooxygenase-2 inhibitors, all affect the cardiovascular system. One of the reasons is that many agents reach targets in the microenvironment and do not affect only the tumor. Combination therapy often amplifies cardiotoxicity, and radiotherapy can also cause heart problems, particularly when combined with chemotherapy. In the past, cardiotoxic risk was less evident, but it is increasingly an issue, particularly with combination therapy and adjuvant therapy. Today's oncologists must be fully aware of cardiovascular risks to avoid or prevent adverse cardiovascular effects, and cardiologists must now be ready to assist oncologists by performing evaluations relevant to the choice of therapy. There is a need for cooperation between these two areas and for the development of a novel discipline, which could be termed cardio-oncology or onco-cardiology. Here, we summarize the potential cardiovascular toxicities for a range of cancer chemotherapeutic and chemopreventive agents and emphasize the importance of evaluating cardiovascular risk when patients enter into trials and the need to develop guidelines that include collateral effects on the cardiovascular system. We also discuss mechanistic pathways and describe several potential protective agents that could be administered to patients with occult or overt risk for cardiovascular complications. |
6,042 | Extracorporeal cardiac mechanical stimulation: precordial thump and precordial percussion. | External cardiac mechanical stimulation is one of the fastest resuscitative manoeuvres possible in the emergency setting. Precordial thump (PT), initially reported for treatment of atrio-ventricular block, has been subsequently described to cardiovert also ventricular tachycardia (VT) and fibrillation (VF). PT efficacy, mechanics and mechanisms remain poorly characterized.</AbstractText>Appropriate MESH and free terms were searched on PubMed, Embase and the Cochrane Library. Cross-referencing from articles and reviews, and forward search using SCOPUS and Google scholar have also been performed. Pre-set inclusion and exclusion criteria were applied to retrieved references on PT, which were then reviewed, summarized and interpreted.</AbstractText>PT is not effective in treating VF, and of limited use for VT, although it has a very good safety profile (97% no changed/improved rhythm). If delivered, PT should be applied as early as possible after cardiac arrest, and cardio-pulmonary resuscitation (CPR) should begin with no delay if not effective.</AbstractText>A relatively large fraction of reported positive outcomes (both for PT and the less forceful but serially applied precordial percussion) in witnessed asystole should be considered when critically reviewing present CPR recommendations. In addition, mechanisms, energy requirements and timing are analysed and discussed.</AbstractText>The 2005 ALS guidelines recommend PT delivery only by healthcare professionals trained in the technique. The use of training aids should therefore be explored, regardless of whether they are based on stand-alone devices or integrated within resuscitation mannequins.</AbstractText> |
6,043 | Outcome after resuscitation using controlled rapid extracorporeal cooling to a brain temperature of 30 degrees C, 24 degrees C and 18 degrees C during cardiac arrest in pigs. | To identify the optimal level of hypothermia during cardiac arrest, just prior to resuscitation with an extracorporeal cooling system and without fluid overload, for neurological outcome at day 9 in pigs.</AbstractText>In a prospective randomised laboratory investigation, 24 female Large White pigs (31-38 kg) underwent ventricular-fibrillation cardiac arrest for 15 min, followed by 1 min, 3 min or 5 min (n=8 per group) of 4 degrees C cooling with an extracorporeal cooling system via an aortic balloon catheter and resuscitation with cardiopulmonary bypass. Sixty minutes following induction of cardiac arrest, defibrillation attempts were started. Mild hypothermia (34.5 degrees C) and intensive care were continued for 20 h and final outcome was evaluated after 9 days.</AbstractText>Brain temperature decreased from 38.5 degrees C to 30.4+/-1.6 degrees C within 221+/-81 s in the 1-min group; to 24.2+/-4.6 degrees C within 375+/-127 s in the 3-min group; and to 18.8+/-4.0 degrees C within 450+/-121 s in the 5-min group. Restoration of spontaneous circulation was achieved in seven (1-min group), six (3-min group) and six (5-min group) animals (p=0.78), whereas survival to 9 days was only achieved in six, three and three animals in each group (p=0.22), respectively.</AbstractText>An extracorporeal cooling system rapidly induced brain hypothermia following prolonged normovolaemic cardiac arrest in pigs. Difference in outcome was not statistically significant amongst the three groups with various levels of hypothermia (30 degrees C, 24 degrees C and 18 degrees C) during cardiac arrest prior to resuscitation; however, the animals with the least temperature reduction showed a trend to better survival at 9 days. Further studies are necessary to investigate optimised methods for induction, as well as level, of cerebral hypothermia.</AbstractText>Copyright 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,044 | Intraoperative drug-eluting stent thrombosis in a patient undergoing robotic prostatectomy. | Insertion of drug-eluting stents is one of the strategies for treating patients with coronary artery disease. These patients can be a perioperative challenge in management as they need to be maintained on antiplatelet therapy to prevent stent thrombosis, which puts them at an increased risk for surgical bleeding. Recently revised guidelines on elective surgery following insertion of a drug-eluting stent recommend dual antiplatelet therapy for a period of twelve months. The management of a patient who presented for surgery more than two years after the insertion of a drug-eluting stent, and who developed in-stent thrombosis intraoperatively, is presented. |
6,045 | Automated external defibrillators and survival after in-hospital cardiac arrest: early experience at an Australian teaching hospital. | To evaluate the effect of the introduction of automated external defibrillators (AEDs) on survival after inhospital cardiac arrest.</AbstractText><AbstractText Label="DESIGN, SETTING AND PARTICIPANTS" NlmCategory="METHODS">Before-and-after study that compared patients during the 2 years before (8 November 2005 to 7 November 2007) and the year after (8 November 2007 to 7 November 2008) the deployment of AEDs to the non-critical care areas of a university teaching hospital.</AbstractText>Return of spontaneous circulation (ROSC) and survival to hospital discharge.</AbstractText>55 in-hospital cardiac arrests occurred in the 2-year pre-AED period and 31 in the 1-year AED period. Patients had similar baseline characteristics in the pre-AED and AED periods including witnessed arrest (53% v 48%), arrest in an acute inpatient ward (78% v 90%), and initial arrest rhythm of pulseless ventricular tachycardia or ventricular fibrillation (18% v 16%). The proportions of patients with ROSC were similar in the pre-AED and AED periods (42% v 55%), as were the proportions who survived to hospital discharge (22% v 29%). In the AED period, the relative risk of ROSC was 1.31 (95% CI, 0.84- 2.04) and the relative risk of survival to hospital discharge was 1.33 (95% CI, 0.63-2.80).</AbstractText>ROSC and survival to hospital discharge did not change significantly after deployment of AEDs. The existence of a timely and robust resuscitation response with relatively good baseline outcomes, and the low proportion of initial shockable arrest rhythms may have limited the capacity of AEDs to improve survival.</AbstractText> |
6,046 | [A ventricle of all dangers: a clinical observation and evolution of a case of arrythmogenic right ventricular dysplasia]. | Arrythmogenic right ventricular dysplasia (ARVD) is rare disease but it is a major cause of sudden death in young people and in athletes. ARVD is a cardiomyopathy characterized by structural and functional abnormalities of the right ventricle precipitating its electrical instability. This electrical instability is responsible for ventricular arrhythmias. Sudden death, by ventricular fibrillation, may be the first symptom of the disease. The diagnosis is based upon specific ventricular pathology at the histological level as well as typical electrocardiographic and diagnostic imaging features. A better understanding of the disease has increased along with the new data on genetics. Its management remains a challenge because of the wide spectrum of clinical presentation as well as its natural history. We present a case of ARVD and its evolution in order to show the difficulties of the management of this particular entity. |
6,047 | Atrial fibrillation is an independent determinant of increased NT-proBNP levels in outpatients with signs and symptoms of heart failure. | N-terminal pro-B-type natriuretic peptide (NT-proBNP) is increasingly used in the diagnosis and prognostic assessment of heart failure; however, the possible influence of atrial fibrillation on BNP is still a matter of controversy. We assessed the influence of atrial fibrillation on NT-proBNP levels in outpatients with signs and symptoms of heart failure.</AbstractText>Consecutive outpatients (n = 306) referred to a university hospital heart-failure clinic for evaluation of signs and symptoms of heart failure underwent clinical and echocardiographic assessment and had their NT-proBNP levels determined in a sandwich chemiluminescent immunoassay with two antibodies on an Elecsys analyzer. The influence of atrial fibrillation on NT-proBNP levels was assessed using a non-parsimonious linear regression model with propensity score adjustments to balance for possible confounders.</AbstractText>Atrial fibrillation was associated with increased NT-proBNP levels in patients with (median concentration 1944 vs. 1390 pg/ml) and without (1093 vs. 172 pg/ml) underlying structural disease (P < 0.001). In a linear regression model with a propensity score, atrial fibrillation emerged as an independent determinant of NT-proBNP levels (P = 0.023), even after allowing for possible confounders (left ventricular ejection fraction and end-diastolic diameter, left atrial diameter, mitral insufficiency, age, sex, NYHA class or heart rate).</AbstractText>Atrial fibrillation is an independent determinant of increased NT-proBNP levels. This association should be taken into account when NT-proBNP levels are used in the diagnosis of heart failure in patients with atrial fibrillation.</AbstractText> |
6,048 | Incidence and characteristics of newly diagnosed rheumatic heart disease in urban African adults: insights from the heart of Soweto study. | Little is known on the incidence and clinical characteristics of newly diagnosed rheumatic heart disease (RHD) in adulthood from urban African communities in epidemiologic transition.</AbstractText>Chris Hani Baragwanath Hospital services the black African community of 1.1 million people in Soweto, South Africa. A prospective, clinical registry captured data from all de novo cases of structural and functional valvular heart disease (VHD) presenting to the Cardiology Unit during 2006/07. We describe in detail all cases with newly diagnosed RHD. There were 4005 de novo presentations in 2006/07 and 960 (24%) had a valvular abnormality. Of these, 344 cases (36%) were diagnosed with RHD. Estimated incidence of new cases of RHD for those aged >14 years in the region was 23.5 cases/100 000 per annum. Most were black African females (n = 234-68%) with a similar age profile to males [median 41 (interquartile range 30-55) years vs. 42 (interquartile range 31-55) years]. The predominant valvular lesion (n = 204, 59%) was mitral regurgitation (MR), with 48 (14%) and 43 (13%) cases, respectively, having combination lesions of aortic plus MR and mixed mitral VHD. Impaired systolic function was found in 28/204 cases (14%) of predominant MR and in 23/126 cases (18%) with predominant aortic regurgitation. Elevated right ventricular systolic pressure >35 mmHg (62 cases), atrial fibrillation (34 cases), and anaemia (27 cases) were found in 18, 10, and 8% of 344 RHD cases, respectively. Subsequent valve replacement/repair was performed in 75 patients (22%). A total of 90 cases (26%) were admitted within 30 months of initial diagnosis for suspected bacterial endocarditis.</AbstractText>These data reveal a high incidence of newly diagnosed RHD within an adult urban African community. These data argue strongly for the first episode of RHD to be made a notifiable condition in high burden countries in order to ensure control of the disease through register-based secondary prophylaxis programmes.</AbstractText> |
6,049 | Apical hypertrophic cardiomyopathy associated with multiple coronary artery-left ventricular fistulae: a report of a case and review of the literature. | We present a rare case of multiple coronary artery-left ventricular (LV) fistulae, associated with apical hypertrophic cardiomyopathy in an 83-year-old woman with electrocardiographic abnormalities and a history of arterial hypertension and paroxysmal atrial fibrillation. In order to evaluate the clinical significance and obtain further insights into this unusual disease, the patient has undergone coronary angiography, left ventriculography, and magnetic resonance imaging which better substantiated the structural abnormalities of the LV and the coronary network. |
6,050 | [Efficacy of procainamide in the treatment of refractory ventricular fibrillation: report of 4 cases and a review of the literature]. | Ventricular fibrillation is the most common malignant arrhythmia, found in up to 55% of patients who go on to experience cardiac arrest. Only monophasic or biphasic defibrillation has been shown to be effective. The efficacy of antiarrhythmic drugs is much lower and depends on how much time has elapsed since the onset of symptoms. In patients with persistent ventricular fibrillation refractory to shocks, treatment options are limited. We report 4 cases in which procainamide was administered at a dosage of 17 mg/kg in 1 minute. Heart rhythm was restored and pulse rate recovered in less than 3 minutes in all cases. |
6,051 | Survival increases with CPR by Emergency Medical Services before defibrillation of out-of-hospital ventricular fibrillation or ventricular tachycardia: observations from the Resuscitation Outcomes Consortium. | Immediate defibrillation is the traditional approach to resuscitation of cardiac arrest due to ventricular fibrillation or tachycardia (VF/VT). Delaying defibrillation to provide chest compressions may improve survival. We examined the effect of the duration of Emergency Medical Services (EMS) cardiopulmonary resuscitation (CPR) prior to first defibrillation on survival in patients with out-of-hospital VF/VT.</AbstractText>From a prospective multi-center observational registry of EMS-treated out-of-hospital cardiac arrest, we identified 1638 EMS-treated cardiac arrests with first recorded rhythm VF/VT or "shockable" and complete data for analysis. Survival to hospital discharge was determined as a function of EMS CPR duration prior to first shock.</AbstractText>Compared to the reference group of first EMS CPR duration < or =45 s, the odds of survival was greater among patients who received between 46 and 195 s of EMS CPR before first shock (46-75 s odds ratio [OR] 1.15, 95% confidence interval [CI] 0.71-1.87; 76-105 s, OR 1.37, 95% CI 0.80-2.35; 106-135 s, OR 1.53, 95% CI 0.96-2.45; 136-165 s, OR 1.24, 95% CI 0.71-2.15; 166-195 s, OR 1.47, 95% CI 0.85-2.52). The benefit of EMS CPR before defibrillation was reduced when the duration of CPR exceeded 195 s (196-225 s, OR 0.95, 95% CI 0.47-1.81; 226-255 s, OR 0.91, 95% CI 0.46-1.79; 256-285 s, OR 0.46, 95% CI 0.17-1.29; 286-315 s, OR 1.29, 95% CI 0.59-2.85). An optimal EMS CPR duration was not identified and no duration achieved statistical significance.</AbstractText>In this observational analysis of VF/VT arrest, between 46 and 195 s of EMS CPR prior to defibrillation was weakly associated with improved survival compared to < or =45 s. Randomized trials are needed to confirm the optimal duration of EMS CPR prior to defibrillation and to assess the impact of first CPR duration on all initial rhythms.</AbstractText>Copyright 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,052 | Precordial thump for cardiac arrest is effective for asystole but not for ventricular fibrillation. | Precordial thump for cardiac arrest remains controversial. Although precordial blows can trigger ventricular fibrillation (VF) (i.e., commotio cordis), they paradoxically have been regarded as potential therapy for cardiac arrest. In commotio cordis, impact energy and resultant peak left ventricular (LV) pressure are important variables in VF initiation.</AbstractText>The purpose of this study was to assess the relationship between LV pressures generated by thumps and their effectiveness in defibrillation of VF or resuscitation of asystole after defibrillation.</AbstractText>After induction of VF, 10 swine each received 18 chest thumps; two sets of three thumps each with a clenched fist, a 30-mph lacrosse ball, and a 40-mph lacrosse ball. If asystole followed defibrillation, manual thumps were given to induce ventricular depolarizations until resumption of spontaneous rhythm.</AbstractText>During VF, generated LV pressure (mmHg) was 263 +/- 52 with manual thumps, 392 +/- 179 with 30-mph ball thumps, and 616 +/- 182 with 40-mph ball thumps (P <.001). None of the 180 thumps terminated VF. All episodes required electrical defibrillation. During asystole, generated LV pressures were greater for thumps that induced ventricular depolarizations than for those that did not (111 +/- 27 mmHg vs 73 +/- 23 mmHg, P <.001). A significant association was observed between induction of ventricular depolarizations and thump-generated LV pressures (odds ratio 2.0 per 10 mmHg rise in LV pressure, 95% confidence interval 1.8-2.1).</AbstractText>Despite generating high LV pressures, precordial thumps were not effective in terminating VF. Based on these data, precordial thump for VF in cardiac arrest victims cannot be recommended but for asystolic victims might be beneficial.</AbstractText> |
6,053 | Differences in atrial fibrillation properties under vagal nerve stimulation versus atrial tachycardia remodeling. | There are many similarities between atrial effects of atrial tachycardia remodeling (ATR) and vagal nerve stimulation (VS): both promote atrial fibrillation (AF), reduce atrial effective refractory period (AERP) and AERP rate accommodation, enhance AERP heterogeneity, and increase inward-rectifier K+ current.</AbstractText>This study sought to compare the consequences of ATR and VS at similar levels of AERP abbreviation in dogs.</AbstractText>ATR dogs (n = 6) were subjected to 7-day atrial tachypacing at 400 beats/min, with radiofrequency-induced atrioventricular block and ventricular demand pacing (80 beats/min) to control ventricular response. VS was applied in 6 matched dogs with stimulation parameters selected to produce similar mean AERP values to ATR dogs.</AbstractText>ATR and VS produced similarly short AERPs (79 +/- 12 and 80 +/- 12 ms, respectively), AERP rate-adaptation loss, and AERP heterogeneity increases. Although both ATR and VS increased AF duration, VS was significantly more effective in AF promotion, with mean AF duration of 992 +/- 134 seconds, versus 440 +/- 240 seconds (P <.05) under ATR. The greater AF-promoting effect of VS was associated with greater mean dominant frequency values during AF (11.7 +/- 1.8 versus 10.0 +/- 1.3 Hz ATR, P <.05). VS greatly enhanced the spatial dominant frequency variability, increasing the coefficient of variation to 15.2 +/- 1.9 Hz, versus 8.9 +/- 1.5 Hz for ATR (P <.05), primarily by increasing the per-dog maximum dominant frequency (15.4 +/- 0.6 Hz versus 12.5 +/- 0.6 for ATR, P <.01).</AbstractText>For matched AERP values, VS promotes AF more strongly than ATR. Despite similar AERP changes, VS produces considerably greater increases in dominant frequencies, particularly maximum values, consistent with previous suggestions that inward-rectifier K+ current enhancement is particularly effective at accelerating and stabilizing spiral wave rotors that maintain AF.</AbstractText> |
6,054 | Severe symptoms in mid and apical hypertrophic cardiomyopathy. | We analyzed the clinical and quantitative echocardiographic characteristics of patients with sub-basal hypertrophic cardiomyopathy (HCM) to define the characteristics of patients (pts) with severe symptoms.</AbstractText>Of 444 pts in a referral-based HCM program, 22 (5%) had midventricular or apical HCM. Quality of life (QoL) questionnaire was administered as an independent confirmer of symptomatic state.</AbstractText>Ten pts were NYHA III and IV, and 12 pts were NYHA I and II; QoL scores (41 +/- 26 vs. 10 +/- 13, P = 0.001) confirmed a priori division of two groups based on NYHA classification. Pts with more severe symptoms were more likely female (70% vs. 25%, P = 0.001) with atrial fibrillation (40% vs. 0%, P = 0.02). They more frequently had midventricular HCM 60% versus 8% (P = 0.01) (mid-LV thickness 17 +/- 6 vs. 12 +/- 2 mm, P = 0.03) and had much smaller LV diastolic volumes 68 +/- 12 versus 102 +/- 22 ml (39 +/- 4 vs. 53 +/- 12 ml/m(2), P = 0.001). Septal E/E' was higher in the severely symptomatic pts (15 +/- 5 vs. 7 +/- 3, P = 0.001) indicating higher estimated LV filling pressure. Midobstruction with apical akinetic chamber was noted in 4/10 pts who developed refractory symptoms. Cardiac mortality was higher in the severely symptomatic patients, 4/10 who had midventricular HCM as compared to 0/12 in the mildly symptomatic apical HCM group (P = 0.03).</AbstractText>In subbasal HCM, pts with severe symptoms have midventricular hypertrophy, with encroachment of the LV cavity and consequent very small LV volumes that may be complicated by mid-LV obstruction. Pts with mid-LV hypertrophy are more symptomatic than those with apical HCM, are often refractory to therapy, and have higher mortality.</AbstractText> |
6,055 | Diversity of molecular forms of plasma brain natriuretic peptide in heart failure--different proBNP-108 to BNP-32 ratios in atrial and ventricular overload. | Recent studies have shown that plasma levels of brain natriuretic peptide (BNP)-32 and proBNP-108 are increased in heart failure (HF) and that the BNP-32 assay kit in current clinical use cross-reacts with proBNP-108. We investigated why proBNP is increased without processing in HF was investigated.</AbstractText><AbstractText Label="DESIGN, SETTING AND PATIENTS" NlmCategory="METHODS">Plasma BNP-32 and proBNP-108 in normal individuals (n=10) and in patients with atrial fibrillation (AF) (n=18) and HF (n=132) was measured. BNP-32 and proBNP-108 in ventricular and atrial tissue and in pericardial fluid using a specific fluorescent enzyme immunoassay following Sep-Pak C18 (Waters, Milford, Massachusetts, USA) cartridge extraction and gel filtration was also measured.</AbstractText>Levels of both BNP-32 and proBNP-108 were higher in HF than in control or AF (both p<0.01), and the levels of these peptides significantly correlated (r=0.94, p<0.001). The proBNP-108/total BNP (BNP-32+proBNP-108) ratio was widely distributed and lower in HF (0.33 (0.17)) than in control (0.41 (0.06), p<0.05) and AF (0.45 (0.04), p<0.002). The proBNP-108/total BNP ratio was higher in HF with ventricular than in HF with atrial overload (0.45 (0.10) vs 0.20 (0.11), p<0.001). Consistent with this finding, the major molecular form were proBNP-108 and BNP-32 in ventricular (n=6, 0.67 (0.04)) and atrial (n=7, 0.76 (0.05), p<0.0001) tissues, respectively. ProBNP-108 was also the major molecular form of BNP in pericardial fluid (n=8, 0.82 (0.05)). The proBNP-108/total BNP ratio increased and decreased with HF deterioration and improvement, respectively.</AbstractText>These results suggest that BNP-32 and proBNP-108 is increased in HF and that the proBNP/total BNP ratio increases in association with pathophysiological conditions such as ventricular overload.</AbstractText> |
6,056 | Evidence for enhanced M3 muscarinic receptor function and sensitivity to atrial arrhythmia in the RGS2-deficient mouse. | Atrial fibrillation (AF) is the most common arrhythmia seen in general practice. Muscarinic ACh receptors (M2R, M3R) are involved in vagally induced AF. M2R and M3R activate the heterotrimeric G proteins, G(i) and G(q), respectively, by promoting GTP binding, and these in turn activate distinct K(+) channels. Signaling is terminated by GTP hydrolysis, a process accelerated by regulator of G protein signaling (RGS) proteins. RGS2 is selective for G(q) and thus may regulate atrial M3R signaling. We hypothesized that knockout of RGS2 (RGS2(-/-)) would render the atria more susceptible to electrically induced AF. One-month-old male RGS2(-/-) and C57BL/6 wild-type (WT) mice were instrumented for intracardiac electrophysiology. Atrial effective refractory periods (AERPs) were also determined in the absence and presence of carbachol, atropine, and/or the selective M3R antagonist darifenacin. Susceptibility to electrically induced AF used burst pacing and programmed electrical stimulation with one extrastimulus. Real-time RT-PCR measured atrial and ventricular content of RGS2, RGS4, M2R, M3R, and M4R mRNA. AERP was lower in RGS2(-/-) compared with WT mice in both the high right atrium (HRA) (30 +/- 1 vs. 34 +/- 1 ms, P < 0.05) and mid right atrium (MRA) (21 +/- 1 vs. 24 +/- 1 ms, P < 0.05). Darifenacin eliminated this difference (HRA: 37 +/- 2 vs. 39 +/- 2 ms, and MRA: 30 +/- 2 vs. 30 +/- 1, P > 0.4). RGS2(-/-) were more susceptible than WT mice to atrial tachycardia/fibrillation (AT/F) induction (11/22 vs. 1/25, respectively, P < 0.05). Muscarinic receptor expression did not differ between strains, whereas M2R expression was 70-fold higher than M3R (P < 0.01). These results suggest that RGS2 is an important cholinergic regulator in the atrium and that RGS2(-/-) mice have enhanced susceptibility to AT/F via enhanced M3 muscarinic receptor activity. |
6,057 | Characterization of cardiac brain natriuretic peptide release in patients with paroxysmal atrial fibrillation undergoing left atrial ablation. | Paroxysmal atrial fibrillation (PAF) is associated with elevated levels of brain natriuretic peptide (BNP). The exact cardiac source and implications of this are currently unknown, as are the effects of left atrial ablation on cardiac BNP release. We sought to investigate BNP levels at different cardiac sites in PAF patients before and after left atrial ablation and compare these with a non-atrial fibrillation control cohort.</AbstractText>Twenty PAF patients (52+/-10 years, 70% men; left ventricular ejection fraction, 55+/-3%) undergoing ablation were studied, BNP levels were measured at different cardiac sites before and after ablation and compared with a control cohort undergoing ablation for left lateral accessory pathways (10 patients, 41+/-11 years; left ventricular ejection fraction, 55+/-4%). In both cohorts, the coronary sinus BNP levels were the greatest. The PAF cohort had significantly greater BNP levels than the control cohort at all sites before and after ablation. Ablation of the left atrium was associated with a significant decrease in coronary sinus BNP levels (P=0.05) and transcardiac BNP gradient (P=0.03). This was not observed in the control cohort.</AbstractText>BNP levels are elevated in PAF, with the highest levels in the coronary sinus. Ablation of the left atrium was associated with an immediate decrease of BNP levels, implicating this as the source.</AbstractText> |
6,058 | [The effect of inhibition of renin-angiotensin system on cardioversion success and recurrences of atrial fibrillation]. | The renin-angiotensin system (RAS) can play an important role as the underlying mechanism for the development and recurrence of atrial fibrillation (AF). In addition, AF itself can lead to atrial structural and/or electrophysiologic remodeling by activating the RAS. This remodeling serves as an arrhythmogenic substrate for AF. Thus, the inhibition of RAS with angiotensin converting-enzyme inhibitor or angiotensin receptor blockers may be a strategy to prevent occurrence and recurrence of AF in certain patients such as those with heart failure and hypertension in associated with left ventricular hypertrophy. In addition, it may facilitate the cardioversion of AF. In this review, we overview the effect of RAS blockers on cardioversion success and recurrence of AF. |
6,059 | Preliminary study on the detection of cardiac arrhythmias based on multiple simultaneous electrograms. | Although implantable cardioverter-defibrillators have improved significantly in the past decades, the algorithms used in the identification of life-threatening arrhythmias are still not accurate enough. Conventional methods commonly misclassify tachycardias, sometimes initiating an unnecessary and uncomfortable treatment. In this paper, we proposed a new method for the identification of ventricular tachycardias and fibrillations based on the comparison of simultaneous electro-grams. Our method could successfully separate supraventricular tachycardias and normal sinus rhythm, which do not require any treatment, from ventricular tachycardias and fibrillation, which are life-threatening arrhythmias and must be terminated, with a sensitivity of 93.0% and a specificity of 92.7% from the comparison of ventricular electrograms. In future studies, the classification using electrograms from the right heart must be improved. |
6,060 | Wireless physiological monitoring system for psychiatric patients. | Patients in psychiatric hospitals that are sedated or secluded are at risk of death or injury if they are not continuously monitored. Some psychiatric patients are restless and aggressive, and hence the monitoring device should be robust and must transmit the data wirelessly. Two devices, a glove that measures oxygen saturation and a dorsally-mounted device that measures heart rate, skin temperature and respiratory rate were designed and tested. Both devices connect to one central monitoring station using two separate Bluetooth connections, ensuring a completely wireless setup. A Matlab graphical user interface (GUI) was developed for signal processing and monitoring of the vital signs of the psychiatric patient. Detection algorithms were implemented to detect ECG arrhythmias such as premature ventricular contraction and atrial fibrillation. The prototypes were manufactured and tested in a laboratory setting on healthy volunteers. |
6,061 | Use of frequency analysis on the ECG for the prognosis of low energy cardioversion treatment of atrial fibrillation. | Electric cardioversion is the most effective therapy for restoring sinus rhythm in patient with atrial fibrillation (AF), however, there is not a guiding criteria for advising on when and in whom it will be successful. The objective of this study was to employ frequency analysis on the surface electrocardiogram (ECG) to predict the outcome of low energy internal cardioversion in patients with AF. Thirty nine patients with AF, for elective DC cardioversion were included in this study. One catheter was positioned in the right atrial appendage and another in the coronary sinus. A voltage step-up protocol (50-300 V) was used for patient cardioversion. Prior to shock delivery, residual atrial activity signal (RAAS) was derived from 60 seconds of surface ECG from defibrillator pads, by bandpass filtering and ventricular activity (QRST) cancellation. Dominant atrial fibrillatory frequency (DAFF) was estimated from the RAAS power spectrum as the dominant frequency within the 3-12 Hz band. DAFF was calculated from whole 60 seconds segment (DAFF_L) and from the finals 10 seconds segment (DAFF_S) of the RAAS. Lower DAFF_L and DAFF_S were found in successfully cardioverted patients than in those nonsuccessful ones, with energy < or =3 and < or =6 joules. Therapy result (employing 3J or less) was predicted in 35/39 (89.7%) patients with DAFF_L=5.40Hz, and DAFF_L was > or =5.75Hz in a 100% of noncardioverted patients. In conclusion, frequency analysis of the RAAS could be useful for predicting success of low energy internal cardioversion of patients with atrial fibrillation. |
6,062 | Predicting defibrillation outcome based on phase of ventricular activity during ICD implantation. | Implantable cardioverter-defibrillators (ICDs) are well known medical device for patients who are at a risk of sudden cardiac death caused by ventricular fibrillation (VF). The relationship between VF mechanisms and successful ICD therapy to terminate of VF is still not well understood. The purpose of this work is to evaluate the timing of ICD therapy as a predictor of successful VF termination. Clinical data sets were recorded from the patients who underwent ICD implantation in 6 Canadian centers. Timing of the defibrillation attempt (phase) was analyzed by using the ICD Marker Channel which monitors and displays cardiac events sensed by ICD. Phase, based on the VF period, was divided into 10 equally distributed bins and number of successful defibrillation episodes in each bin was compared. A total of 187 defibrillation attempts were identified from the 65 subjects. 126 of the defibrillation attempts were successful, while 61 failed. The optimal case was observed at a phase value of 1.2pi with 2 successful attempts. The lowest performance rate was found at a phase value of 1.4pi and 1.8pi with 50% (3 and 2 successful attempts, respectively). The probability of success was analyzed by using generalized estimating equations (GEE) approach with an exchangeable correlation structure. The results of the GEE logistic regression model indicate no correlation between successful defibrillation attempts and phase of ventricular activity during VF (p-value = 0.78). From our results, timing of defibrillation shock attempt is not a factor in successful termination of VF for patients undergoing ICD implantation. |
6,063 | Cardiac arrhythmia classification using wavelets and Hidden Markov Models - a comparative approach. | This paper reports a comparative study of feature extraction methods regarding cardiac arrhythmia classification, using state of the art Hidden Markov Models. The types of beat being selected are normal (N), premature ventricular contraction (V) which is often precursor of ventricular arrhythmia, two of the most common class of supra-ventricular arrhythmia (S), named atrial fibrillation (AF), atrial flutter (AFL), and normal rhythm (N). The considered feature extraction methods are the standard linear segmentation and wavelet based feature extraction. The followed approach regarding wavelets was to observe simultaneously the signal at different scales, which means with different level of focus. Experimental results are obtained in real data from MIT-BIH Arrhythmia Database and show that wavelet transform outperforms the conventional standard linear segmentation. |
6,064 | Medical safety of TASER conducted energy weapon in a hybrid 3-point deployment mode. | TASER conducted energy weapons (CEW) deliver electrical pulses that can temporarily incapacitate subjects. The goal of this paper is to analyze the distribution of TASER CEW currents in the heart and surrounding organs and to understand theoretical chances of triggering cardiac arrhythmias, of capturing the vagus and phrenic nerves and producing electroporation of skeletal muscle structures. The CEW operates in either probe mode or drive-stun (direct contact) mode. There is also a hybrid mode in which current is passed from a single probe to either or both of 2 drive-stun electrodes on the weapon, presumed to be in direct contact with the skin.</AbstractText>The models analyzed herein describe strength-duration thresholds for myocyte excitation and ventricular fibrillation (VF) induction. Finite element modeling (FEM) was used to approximate current density in the heart for worst-case TASER electrode placement. The FEMs theoretically estimated that maximum TASER CEW current densities in the heart and in neighboring organs are at safe levels. A 3-point deployment mode was compared to probe-mode deployment. The margins of safety for the 3-point deployment were estimated to be as high as or higher than for the probe-mode deployment.</AbstractText>Numerical modeling estimated that TASER CEWs were expected to be safe when deployed in 3-point mode. In drive-stun, probe-mode or 3-point deployments, the CEWs had high theoretically approximated safety margins for cardiac capture, VF, phrenic or vagus nerve capture and skeletal muscle damage by electroporation.</AbstractText> |
6,065 | Monitoring intramyocardial reentry using alternating transillumination. | Intramyocardial reentry is implicated as a primary cause of the most deadly cardiac arrhythmias known as polymorphic ventricular tachycardia and ventricular fibrillation. However, the mechanisms involved in the triggering of such reentry and controlling its subsequent dynamics remain poorly understood. One of the major obstacles has been a lack of adequate tools that would enable 3D imaging of electrical excitation and reentry inside thick ventricular wall. Here, we present a new experimental technique, termed alternating transillumination (AT), aimed at filling this gap. The AT technique utilizes a recently synthesized near-infrared fluorescent voltage-sensitive dye, DI-4-ANBDQBS. We apply AT to study the dynamics of reentry during shock-induced polymorphic ventricular tachycardia in pig myocardium. |
6,066 | Spatial heterogeneity of restitution properties and the onset of alternans. | Traditionally, it was believed that cardiac rhythm stability was governed by the slope of the restitution curve (RC), which relates the duration of an action potential to the preceding diastolic interval. However, a single RC does not exist; rate-dependence leads to multiple distinct RCs. We measure spatial differences in the steady-state action potential duration (APD), as well as in three different RCs: the S1-S2 (SRC), constant-basic-cycle-length (BRC), and dynamic (DRC), and correlate these differences with the tissue's propensity to develop alternans. The results show that spatial differences in APD, SRC slope, and DRC slope are correlated with the tissue's propensity to exhibit alternans. These results may lead to a new diagnostic approach to identifying patients with vulnerability to arrhythmias, which will involve pacing at slow rates and analyzing spatial differences in restitution properties. |
6,067 | Effects of hypocalcemia on electrical restitution and ventricular fibrillation. | We have shown previously that verapamil reduces the slope of the action potential duration (APD) restitution relation, suppresses APD alternans and converts ventricular fibrillation (VF) into a periodic rhythm. To determine whether these effects result primarily from reduction of the APD restitution slope, as opposed to alteration of calcium dynamics unrelated to restitution, we tested the effects of hypocalcemia ([CaCl2]=31-125 microM) in canine ventricle. At normal [CaCl2] (2.0 mM), the slope of the APD restitution relation was >1, APD alternans occurred during rapid pacing and VF was inducible. During hypocalcemia the slope of the restitution relation remained >1 and the magnitude of APD alternans was unchanged. VF still was inducible and the mean cycle length and the variance of the FFT spectra during VF were not altered significantly. These results suggest that reduction of APD restitution slope, rather than blockade of ICa per se, is responsible for the antifibrillatory effects of verapamil in this model of pacing-induced VF, lending further support to the idea that APD restitution kinetics is a key determinant of VF. |
6,068 | Influence of channel blockers on cardiac alternans. | Sudden cardiac arrest (SCA) due to fatal cardiac arrhythmias such as ventricular fibrillation is the leading cause of death in the United States, killing 350,000 Americans each year. Thus, it is of great importance to investigate the mechanisms that can suppress abnormal heart rhythms. In this work, we study the effects of drugs such as channel blockers through mathematical modeling of cardiac electrophysiological phenomena. In particular, we carry out multi-level simulations to study how channel blockers affect arrhythmias at cellular, fiber, and tissue levels. Numerical simulations show that the drugs have different effects at different scales (cellular versus fiber or tissue). Moreover, the drugs may appear to be arrhythmic in one model but antiarrhythmic in another. These observations indicate that analysis and simulation based on multiple scales and multiple models are crucial to fully understand the properties of drugs in treating arrhythmias. |
6,069 | Optical mapping of electrical heterogeneities in the heart during global ischemia. | Real-time optical registration of electrical activity in the heart allows the study of arrhythmogenic mechanisms, in particular due to global ischemia. It is known that global ischemia increases electrical heterogeneity in the heart. However, inter-ventricular differences between the right (RV) and left ventricle (LV) during ischemia and their relationship to arrhythmogenesis remains poorly understood. We used high resolution optical mapping (di-4-ANEPPS, excitation at 532 nm, emission at 640+/-50 nm) of Langendorff-perfused rabbit hearts to quantify inter-ventricular heterogeneity in the heart during periodic pacing and ventricular fibrillation. Two fast CCD cameras were used to record electrical activity from the RV and LV during control, global ischemia (20 min), and reperfusion. Hearts were paced at progressively reduced (from 300 ms to 100 ms) basic cycle lengths and ventricular fibrillation was induced by burst pacing and recorded before the global ischemia, and after the reperfusion. The action potential durations (APD), maximum slopes of APD restitution curves (S(max)), and mean dominant frequency (DF) of ventricular fibrillation were measured for both LV and RV surfaces. No APD heterogeneity was observed in control hearts. Global ischemia induced inter-ventricular heterogeneity in APDs (RV: 109+/-21 ms, LV: 89+/-23 ms; p<0.01) that was abolished upon reperfusion. However, S(max) was uniformly decreased in both RV (control: 0.94+/-0.25, ischemia: 0.36+/-0.12; p<0.01) and LV (control: 0.99+/-0.24, ischemia: 0.43+/-0.21; p<0.01) and did not recover upon reperfusion. In addition, the DF of ventricular fibrillation during reperfusion decreased significantly in RV (from 8.6+/-1.3 Hz to 6.2+/-1.1 Hz; p<0.05) but remained the same in LV (9.0+/-0.8 Hz vs 8.5+/-1.0 Hz). Thus, our results demonstrate that global ischemia induces inter-ventricular heterogeneity in APD during periodic pacing. Although this effect was abolished upon reperfusion, S(max) did not recover, indicating the presence of residual changes in electrical properties of the heart. Therefore, reperfusion reveals the presence of inter-ventricular heterogeneities in the dynamics of ventricular fibrillation. |
6,070 | Medium voltage therapy for preventing and treating asystole and PEA in ICDs. | Sudden cardiac death (SCD) takes up to 500,000 lives each year before a victim can even be treated. To address this the implantable cardioverter defibrillator (ICD) was developed to treat those identified at high risk of SCD. Unfortunately, there are a significant number of cases in which the ICD does not successfully return a victim to normal rhythm and effective perfusion of the blood.</AbstractText>The vast majority of cases that are not responsive to the ICD therapy require cardio-pulmonary resuscitation (CPR) according to current resuscitation guidelines. A novel electrical stimulus called medium voltage therapy (MVT) has shown efficacy in producing coronary and carotid blood flow during ventricular fibrillation. This report presents the case that the same stimulus may be effective and feasible for use in ICD patients that do not respond to their ICD therapy, or do not have a rhythm in which, an ICD shock is indicated.</AbstractText>The inclusion of MVT technology in implantable devices may be effective in preparing the heart for successful defibrillation or in improving the metabolic condition of the heart to the extent that a pulsatile rhythm may spontaneously develop.</AbstractText> |
6,071 | Defibrillator synchronization tester. | A defibrillator sync output signal connector provides an ECG synchronization signal that can be used by some defibrillators for the purpose of performing synchronized cardioversion [1]. This process is used to stop an abnormally fast heart rate or cardiac arrhythmia by the delivery of a therapeutic dose of electric current to the heart during the R-wave of the cardiac cycle. Timing the shock to the R-wave prevents the delivery of the shock during the vulnerable period of the cardiac cycle, which could induce ventricular fibrillation [2]. GE patient monitors include a selectable analog output feature, which provides an analog ECG or arterial blood pressure signal. The blood pressure signal can be used to synchronize balloon pumps to provide cardiac assist to post-MI patients with poor injection fraction. Proper operation requires the defibrillator sync and analog output function to be checked. Checkouts are typically done during planned maintenance and after major part replacements such as patient monitor's main CPU board. Checking out defibrillator sync signals could be done using a GE defibrillator sync tester. The defibrillator sync tester provides a loop back path for the defibrillator sync signals to be displayed on the patient monitor screen and eliminates the need for an external oscilloscope. |
6,072 | Electrocardiogram signals identification for cardiac arrhythmias using prony's method and neural network. | A new method is presented to identify Electrocardiogram (ECG) signals for abnormal heartbeats based on Prony's modeling algorithm and neural network. Hence, the ECG signals can be written as a finite sum of exponential depending on poles. Neural network is used to identify the ECG signal from the calculated poles. Algorithm classification including a multi-layer feed forward neural network using back propagation is proposed as a classifying model to categorize the beats into one of five types including normal sinus rhythm (NSR), ventricular couplet (VC), ventricular tachycardia (VT), ventricular bigeminy (VB), and ventricular fibrillation (VF). |
6,073 | Optimizing cardiac resuscitation outcomes using wavelet analysis. | Ventricular fibrillation (VF) is the most lethal of cardiac arrhythmias that leads to sudden cardiac death if untreated within minutes of its occurrence. Defibrillation using electric shock resets the heart to return to spontaneous circulation (ROSC) state, however the success of which depends on various factors such as the viability of myocardium and the time lag between the onset of VF to defibrillation. Recent studies have reported that performing cardio pulmonary resuscitation (CPR) procedure prior to applying shock increases the survival rate especially when VF is untreated for more than 5 minutes. Considering the limited time within which the VF has to be treated for better survival rates, the choice of the right therapy (shock parameters, shock first or CPR first, drug administration) is vital. In aiding this choice, it would be of immense help for emergency medical staff (EMS) if an objective feedback could be provided at near real-time rate on the VF characteristics and its relation to the shock outcomes. Existing works in the literature have demonstrated correlation between the characteristics of the VF waveform and the outcome (ROSC) of the defibrillation. The proposed work improves on this by attempting to arrive at a near real-time monitoring tool in aiding the EMS staff. Using data collected from 16 pigs during VF, the proposed wavelet methodology achieved an overall accuracy of 94% in successfully predicting the shock outcomes. |
6,074 | System to improve AED resuscitation using interactive CPR coaching. | A positive impact on cardiac arrest survival has been demonstrated with the substantial reduction in time to defibrillation provided by the widespread deployment of automated external defibrillators (AEDs). However, recent studies have identified the importance of performing chest compressions before defibrillation in facilitating effective recovery from long duration ventricular fibrillation (VF). Despite the importance of cardiopulmonary resuscitation (CPR), effective performance of it in the field is hampered by many problems including the dependence on rescuer technique, which is known to be variable even with trained professionals. This research seeks to enhance survival outcomes following resuscitation. A full experimental system was developed that used an instrumented CPR manikin to provide interactive CPR coaching while collecting performance data. This system was utilized in a controlled human CPR performance study comparing the differences in chest compression performance with and without visual coaching and with and without interactive performance feedback coaching. Results from the human study support a number of conclusions and recommendations. In general using any type of coaching provided improvements in all of the CPR performance measures excluding chest recoil where there was a slight decrease in performance. The statistical results also indicated that the audio/visual coaching conditions provided a more effective coaching condition with respect to chest compression rate. Most notably, the feedback conditions both provided a statistically significant or trends toward improving chest compression effectiveness and produced superior performance as a whole. |
6,075 | Human feasibility study of hemodynamic monitoring via continuous intrathoracic impedance monitoring. | The ultimate hemodynamic sensor for an implantable device would provide information about cardiovascular performance including systolic function, diastolic function, preload, and afterload. We examined the potential clinical utility of simultaneous measurement of left ventricular pressure and continuous intrathoracic impedance in a group of 20 patients undergoing acute intravenous ablation for atrial fibrillation. Following baseline measurements of traditional left ventricular (LV) conductance volume (control), LV pressure and conductance measurement were repeated using alternate impedance stimulation and sensing vectors that encompassed combinations of the lung, left ventricle, right ventricle and left atrium, respectively. Various relative indices of LV function, including end systolic pressure to volume (conductance) ratio, end diastolic pressure to volume (conductance) ratio, and preload recruitable stroke work (analog) were derived by combining real-time pressure and conductance. The raw morphometry of the LV vector seemed to most closely resemble the gold standard LV conductance volume. For this vector, strong linear correlations between LV pressure and end systolic conductance (r = 0.84 + or - 0.14), end diastolic conductance (r = 0.78 + or - 0.10) and preload recruitable stroke work analog (r = 0.93 + or - 0.05) were observed. The LV vector provides a robust continuous intracardiac hemodynamic signal that may be useful for quantifying cardiovascular function. |
6,076 | Relation of 12-lead electrocardiogram patterns to implanted defibrillator-terminated ventricular tachyarrhythmias in hypertrophic cardiomyopathy. | Electrocardiographic (ECG) abnormalities are common in hypertrophic cardiomyopathy (HC) and have been associated with the distribution of left ventricular hypertrophy and myocardial fibrosis. Such abnormalities may predispose patients to electrophysiologic instability, ventricular arrhythmias, and sudden cardiac death (SCD). We studied 330 patients with HC who were judged clinically to be at high risk for SCD and therefore received automatic implantable cardioverter-defibrillators (ICDs). Surface 12-lead electrocardiograms acquired at the time of ICD implantation were analyzed and the ECG characteristics of patients with appropriate device interventions for ventricular tachycardia and fibrillation were compared to those patients without appropriate device interventions. The 330 patients were followed for 3.7 +/- 3.0 years after implantation and 57 patients (17%) had appropriate discharges. No differences in the ECG characteristics of patients with and without appropriate device interventions were identified. Markedly increased ECG voltages, QRS duration, left or rightward QRS axis, abnormal Q waves, and QTc or QT dispersion were not associated with appropriate ICD discharge. Conversely, normal electrocardiograms and electrocardiograms normal except for a repolarization abnormality in only 1 anatomic distribution were not associated with freedom from ICD discharge. Moreover, no combination of ECG variables was associated with the likelihood of an appropriate ICD discharge. In conclusion, in a cohort of patients with HC selected because of their high risk for SCD, 12-lead surface electrocardiogram did not predict subsequent appropriate ICD intervention for ventricular tachyarrhythmias and was not useful in risk stratification for sudden death. |
6,077 | Impact of prior statin therapy on arrhythmic events in patients with acute coronary syndromes (from the Global Registry of Acute Coronary Events [GRACE]). | Animal models of myocardial ischemia have demonstrated reduction in arrhythmias using statins. It was hypothesized that previous statin therapy before hospitalization might be associated with reductions of in-hospital arrhythmic events in patients with acute coronary syndromes. In this multinational, prospective, observational study (the Global Registry of Acute Coronary Events [GRACE]), data from 64,679 patients hospitalized for suspected acute coronary syndromes (from 1999 to 2007) were analyzed. The primary outcome of interest was in-hospital arrhythmic events in previous statin users compared with nonusers. The 2 primary end points were atrial fibrillation and the composite end point of ventricular tachycardia, ventricular fibrillation, and/or cardiac arrest. In-hospital death was also examined. Of the 64,679 patients, 17,636 (27%) had received previous statin therapy. Those taking statins had higher crude rates of histories of angina (69% vs 46%), diabetes (34% vs 22%), heart failure (15% vs 8.4%), hypertension (74% vs 58%), atrial fibrillation (9.3% vs 7.0%), and dyslipidemia (85% vs 35%). Patients previously taking statins were less likely to have in-hospital arrhythmias. In propensity-adjusted multivariable models, previous statin use was associated with a lower risk for ventricular tachycardia, ventricular fibrillation, or cardiac arrest (odds ratio 0.81, 95% confidence interval 0.72 to 0.96, p = 0.002); atrial fibrillation (odds ratio 0.81, 95% confidence interval 0.73 to 0.89, p <0.0001); and death (odds ratio 0.82, 95% confidence interval 0.70 to 0.95, p = 0.010). In conclusion, patients previously taking statins had a lower incidence of in-hospital arrhythmic events after acute coronary syndrome than those not previously taking statins. Our study suggests another possible benefit from appropriate primary and secondary prevention therapy with statins. |
6,078 | Cardiac arrhythmias induced by glutathione oxidation can be inhibited by preventing mitochondrial depolarization. | We have previously proposed that the heterogeneous collapse of mitochondrial inner membrane potential (DeltaPsi(m)) during ischemia and reperfusion contributes to arrhythmogenesis through the formation of metabolic sinks in the myocardium, wherein clusters of myocytes with uncoupled mitochondria and high K(ATP) current levels alter electrical propagation to promote reentry. Single myocyte studies have also shown that cell-wide DeltaPsi(m) depolarization, through a reactive oxygen species (ROS)-induced ROS release mechanism, can be triggered by global depletion of the antioxidant pool with diamide, a glutathione oxidant. Here we examine whether diamide causes mitochondrial depolarization and promotes arrhythmias in normoxic isolated perfused guinea pig hearts. We also investigate whether stabilization of DeltaPsi(m) with a ligand of the mitochondrial benzodiazepine receptor (4'-chlorodiazepam; 4-ClDzp) prevents the formation of metabolic sinks and, consequently, precludes arrhythmias. Oxidation of the GSH pool was initiated by treatment with 200 microM diamide for 35 min, followed by washout. This treatment increased GSSG and decreased both total GSH and the GSH/GSSG ratio. All hearts receiving diamide transitioned from sinus rhythm into ventricular tachycardia and/or ventricular fibrillation during the diamide exposure: arrhythmia scores were 5.5+/-0.5; n=6 hearts. These arrhythmias and impaired LV function were significantly inhibited by co-administration of 4-ClDzp (64 microM): arrhythmia scores with diamide+4-ClDzp were 0.4+/-0.2 (n=5; P<0.05 vs. diamide alone). Imaging DeltaPsi(m) in intact hearts revealed the heterogeneous collapse of DeltaPsi(m) beginning 20 min into diamide, paralleling the timeframe for the onset of arrhythmias. Loss of DeltaPsi(m) was prevented by 4-ClDzp treatment, as was the increase in myocardial GSSG. These findings show that oxidative stress induced by oxidation of GSH with diamide can cause electromechanical dysfunction under normoxic conditions. Analogous to ischemia-reperfusion injury, the dysfunction depends on the mitochondrial energy state. Targeting the mitochondrial benzodiazepine receptor can prevent electrical and mechanical dysfunction in both models of oxidative stress. |
6,079 | A population-based investigation of public access defibrillation: role of emergency medical services care. | Although strategic use of public access defibrillation (PAD) can improve cardiac arrest survival, little is known about temporal trends in PAD deployment and use or how PAD affects the role of emergency medical services (EMS). We sought to determine the frequency, circumstances, and time trends of PAD AED and determine implications of PAD use for EMS providers.</AbstractText>The investigation was a population-based cohort study of treated out-of-hospital cardiac arrest from a heterogeneous metropolitan setting between January 1, 1999 and December 31, 2006. The study focused on cases where a PAD AED was applied.</AbstractText>During the 8-year period, a PAD AED was applied in 1.5% (157/10,332) of all arrests and 4.4% (122/2759) of ventricular fibrillation arrests. PAD application increased over time overall (0.6% in 1999 to 2.4% in 2006) and among ventricular fibrillation arrests (1.8% in 1999 to 8.2% in 2006) (p<0.001 test for trend). Upon EMS arrival, over 90% (143/157) of PAD cases were unconscious and 73% (114/157) required CPR. EMS defibrillation occurred in 47% (73/157). Advanced life support included intubation in 85% (134/157), epinephrine treatment in 57% (90/157), and antiarrhythmic treatment in 64% (100/157). By the end of EMS care, spontaneous pulses were present in 76% (120/157) overall and 84% (102/122) of ventricular fibrillation arrests, a 50% absolute increase when compared to status upon EMS arrival.</AbstractText>PAD AED increased over time. Most PAD patients were pulseless upon EMS arrival and required basic and advanced resuscitation care by EMS; yet most subsequently achieved spontaneous circulation.</AbstractText>Copyright 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,080 | Cardiac adrenergic control and atrial fibrillation. | Atrial fibrillation (AF) is the most common cardiac arrhythmia, and it causes substantial mortality. The autonomic nervous system, and particularly the adrenergic/cholinergic balance, has a profound influence on the occurrence of AF. Adrenergic stimulation from catecholamines can cause AF in patients. In human atrium, catecholamines can affect each of the electrophysiological mechanisms of AF initiation and/or maintenance. Catecholamines may produce membrane potential oscillations characteristic of afterdepolarisations, by increasing Ca(2+) current, [Ca(2+)](i) and consequent Na(+)-Ca(2+) exchange, and may also enhance automaticity. Catecholamines might affect reentry, by altering excitability or conduction, rather than action potential terminal repolarisation or refractory period. However, which arrhythmia mechanisms predominate is unclear, and likely depends on cardiac pathology and adrenergic tone. Heart failure (HF), a major cause of AF, causes adrenergic activation and adaptational changes, remodelling, of atrial electrophysiology, Ca(2+) homeostasis, and adrenergic responses. Chronic AF also remodels these, but differently to HF. Myocardial infarction and AF cause neural remodelling that also may promote AF. beta-Adrenoceptor antagonists (beta-blockers) are used in the treatment of AF, mainly to control the ventricular rate, by slowing atrioventricular conduction. beta-Blockers also reduce the incidence of AF, particularly in HF or after cardiac surgery, when adrenergic tone is high. Furthermore, the chronic treatment of patients with beta-blockers remodels the atria, with a potentially antiarrhythmic increase in the refractory period. Therefore, the suppression of AF by beta-blocker treatment may involve an attenuation of arrhythmic activity that is caused by increased [Ca(2+)](i), coupled with effects of adaptation to the treatment. An improved understanding of the involvement of the adrenergic system and its control in basic mechanisms of AF under differing cardiac pathologies might lead to better treatments. |
6,081 | Arrhythmogenic mechanisms of the Purkinje system during electric shocks: a modeling study. | The function of the Purkinje system (PS) is to ensure fast and uniform activation of the heart. Although this vital role during sinus rhythm is well understood, this is not the case when shocks are applied to the heart, especially in the case of failed defibrillation. The PS activates differently from the myocardium, has different electrophysiological properties, and provides alternate propagation pathways; thus, there are many ways in which it can contribute to postshock behavior.</AbstractText>The purpose of this study was to elucidate the role of the PS in the initiation and maintenance of postshock arrhythmias.</AbstractText>A computer model of the ventricles including the PS was subjected to different reentry induction protocols.</AbstractText>The PS facilitated reentry induction at relatively weaker shocks. Disconnecting the PS from the ventricles during the postshock interval revealed that the PS helps stabilize early-stage reentry by providing focal breakthroughs. During later stages, the PS contributed to reentry by leading to higher frequency rotors. The PS also promoted wave front splitting during reentry due to electrotonic coupling, which prolongs action potential durations at PS-myocyte junctions. The presence of a PS results in the anchoring of reentrant activations that propagate through the pathways provided by the PS.</AbstractText>The PS is proarrhythmic in that it provides pathways that prolong activity, and it plays a supplementary role in maintaining the later stages of reentry (>800 ms).</AbstractText> |
6,082 | Cryoablation of stellate ganglia and atrial arrhythmia in ambulatory dogs with pacing-induced heart failure. | There is an association between autonomic nerve discharges and atrial arrhythmias (including bradycardia and tachycardia) in ambulatory dogs with pacing-induced heart failure (HF).</AbstractText>The purpose of this study was to test the hypothesis that stellate ganglia ablation can reduce the incidence of atrial arrhythmias in a canine model of pacing-induced HF.</AbstractText>Cryoablation of the caudal half of the left and right stellate ganglia and T2-T4 thoracic sympathetic ganglia was performed in six dogs (experimental group). Left upper stellate ganglia nerve activity, vagal nerve activity, and electrocardiogram were continuously recorded using an implanted radiotransmitter.</AbstractText>After 2 weeks of baseline recording, rapid right ventricular pacing (28 +/- 4 days) was used to induce HF. The control group (N = 6) underwent the same procedures except for cryoablation. The experimental group had no episodes of paroxysmal atrial tachycardia (P <.0001 vs control). Cryoablation significantly (P = .0097) reduced prolonged (>3 seconds) sinus pause episodes from 5 +/- 6 to 0 on day 1, from 250 +/- 424 to 11 +/- 11 on day 7, and from 123 +/- 206 to 30 +/- 33 on day 14 after induction of HF. In the experimental group only, vagal nerve activity may occur alone without concomitant stellate ganglia nerve activity. However, these isolated vagal nerve activity episodes did not result in prolonged sinus pause. Histologic studies confirmed successful cryoablation of the caudal half of the stellate ganglia.</AbstractText>Cryoablation of bilateral stellate and T2-T4 thoracic ganglia significantly reduced paroxysmal atrial tachycardia and prolonged sinus pause episodes induced by sympathetic discharges in dogs with pacing-induced HF.</AbstractText> |
6,083 | Association of TGFBR2 polymorphism with risk of sudden cardiac arrest in patients with coronary artery disease. | Transforming growth factor ss (TGFss) signaling has been shown to promote myocardial fibrosis and remodeling with coronary artery disease (CAD), and previous studies show a major role for fibrosis in the initiation of malignant ventricular arrhythmias (VA) and sudden cardiac arrest (SCA). Common single nucleotide polymorphisms (SNPs) in TGFss pathway genes may be associated with SCA.</AbstractText>We examined the association of common SNPs among 12 candidate genes in the TGFss pathway with the risk of SCA.</AbstractText>SNPs (n = 617) were genotyped in a case-control study comparing 89 patients with CAD and SCA caused by VA to 520 healthy control subjects.</AbstractText>Nineteen SNPs among 5 genes (TGFB2, TGFBR2, SMAD1, SMAD3, SMAD6) were associated with SCA after adjustment for age and sex. After permutation analysis to account for multiple testing, a single SNP in TGFBR2 (rs9838682) was associated with SCA (odds ratio: 1.66, 95% confidence interval: 1.08 to 2.54, P = .02).</AbstractText>We show an association between a common TGFBR2 polymorphism and risk of SCA caused by VA in the setting of CAD. If validated, these findings support the role of genetic variation in TGFss signaling in SCA susceptibility.</AbstractText> |
6,084 | Evidence of clinical practice heterogeneity in the use of implantable cardioverter-defibrillators in heart failure and post-myocardial infarction left ventricular dysfunction: Findings from IMPROVE HF. | Clinical guidelines recommend implantable cardioverter-defibrillators (ICDs) for selected patients with chronic left ventricular dysfunction (LVD) to improve survival, yet ICD treatment rates for eligible patients with LVD or heart failure (HF) in cardiology practices remain poorly studied.</AbstractText>This study sought to determine patient and practice characteristics associated with ICD use in the outpatient setting.</AbstractText>IMPROVE HF (Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting), a prospective cohort study, is designed to characterize management of HF with reduced left ventricular ejection fraction (LVEF < or =35%). Baseline data were collected for 15,381 patients attending 167 outpatient cardiology practices located in the U.S.</AbstractText>By current guidelines, 7,221 patients met eligibility for ICD implantation (+/- cardiac resynchronization therapy [CRT]), of whom 3,659 (50.7%) received either ICD (63.8%) or CRT with defibrillator (36.2%). Individual practice conformity for guideline-recommended ICD use ranged from 0% to 100% (27.3% to 74.6% at the 10th and 90th percentiles, respectively). Adjusted analyses revealed lack of adherence for ICD use most notably with advancing age (odds ratio: 0.87; 95% confidence interval: 0.82 to 0.93 per 10 years), black race (odds ratio: 0.75; 95% confidence interval: 0.60 to 0.94), and lack of insurance (odds ratio: 0.45; 95% confidence interval: 0.26 to 0.78). Characteristics of increased adherence included male sex, ischemic disease, atrial fibrillation, and wider QRS. Practices in the Northeast U.S. were more likely to adhere to guidelines (P <.001), as were those with a dedicated HF clinic (P = .004) and electrophysiologists on staff (P <.001).</AbstractText>Although a number of patient and practice characteristics are associated with guideline-based ICD use, there is significant unexplained variation in the use of ICD therapy for sudden death prophylaxis across cardiology practices.</AbstractText> |
6,085 | Antiarrhythmic effect of acute oxygen-ozone administration to rats. | The antiarrhythmic effects of 100; 150; and 300microg/kg i.p. oxygen/ozone mixture were tested on arrhythmias induced by i) ischemia; ii) ischemia/reperfusion; iii) aconitine (15microg/kg/i.v.); potassium chloride (1.5% i.v.) in rats. 25min of cardiac left descending coronary artery ischemia caused severe incidence of ventricular tachycardia, ventricular fibrillation and mortality. These were significantly reduced by pre-treatment of rats with oxygen/ozone mixture at doses of 150 and 300microg/kg. In separate experiments using a protocol of 5min ischemia followed by 8min reperfusion this caused arrhythmias starting within 6+/-1s. The incidence of ventricular tachycardia was 100%, while ventricular fibrillation occurred in 75% of the animals and lasted 85+/-14s. The mortality was 62.5%. These figures were significantly (P<0.01) reduced in animals treated with 150microg/kg oxygen/ozone and a substantial increase observed with 300microg/kg, whilst not affected by the lower dose of 100microg/kg. 150 and 300microg/kg oxygen/ozone prolonged the onset time for the appearance of arrhythmias induced by aconitine (300microg/kg oxygen/ozone, approximately 81% longer). Oxygen/ozone also reduced the ventricular tachycardia duration, ventricular fibrillation incidence, arrhythmia score, and increased the rat's survival rate. As for example, this latter was increased from 25% (aconitine) to 50% (aconitine+oxygen/ozone 150microg/kg). 100microg/kg oxygen/ozone was without effect. None of the oxygen/ozone doses affected the arrhythmias caused by potassium chloride 1.5% i.v. All the oxygen/ozone antiarrhythmic effects were similar to those observed with lidocaine (1.5mg/kg i.v.). In conclusion, oxygen/ozone has antiarrhythmic effects against arrhythmias caused by aconitine, myocardial ischemia and ischemia/reperfusion. |
6,086 | Thromboembolism in patients with atrial fibrillation with and without left atrial thrombus documented by transesophageal echocardiography. | The incidence of cerebrovascular events (CVEs) was investigated in 95 consecutive patients with atrial fibrillation (AF) with left atrial thrombus (LAT) diagnosed by transesophageal echocardiography (TEE) and in 131 age- and sex-matched AF patients without LAT. Compared with patients without LAT, patients with LAT had a larger left atrial diameter (49 versus 44 mm, P < 0.0001), a lower left ventricular ejection fraction (40% versus 50%, P < 0.0001), a higher prevalence of spontaneous echocardiographic contrast (88% versus 25%, P < 0.001), a reduced left atrial appendage emptying velocity (0.25 versus 0.41 cm/s, P < 0.0001), and less use of antiarrhythmic drugs (61% versus 76%, P = 0.03). Before TEE, the prevalence of prior CVE was higher in LAT patients (20%) compared with patients without LAT (8%) (P = 0.01). Fifty-four of 95 LAT patients (57%) and 81 of 131 non-LAT patients (62%) were on warfarin before TEE. The incidence of prior CVE in LAT patients without warfarin (32%) was higher than that in non-LAT patients without warfarin (10%) (P = 0.02). The mortality rate in LAT patients with an international normalized ratio (INR) >or= 2.0 (42%) was higher than that in patients without LAT and an INR >or= 2.0 (11%) (P < 0.001). Fifty-one of 95 LAT patients (54%) underwent repeat TEE before cardioversion (48 patients received warfarin therapy). The thrombus resolved in 40 of 51 patients (78%) after the first TEE. There was no significant difference in INR between the patients with persistent and resolved LAT. AF patients with persistent LAT had a higher incidence of CVE (45%) than the patients with resolved LAT (5%) (P = 0.003). We suggest that patients with LAT be treated with warfarin to maintain an INR between 2.5 and 3.5 rather than between 2.0 and 3.0 because they are at a high risk for new thromboembolism. |
6,087 | Ventricular late potential in patients with apparently normal electrocardiogram; predictor of Brugada syndrome. | Brugada syndrome can be overlooked due to its dynamic change in its electrocardiogram (ECG) manifestation. We hypothesized that positive ventricular late potential (VLP) in patients with nonspecific ECG would predict the inducible coved ST elevation (type-1 Brugada ECG) and the patients at high risk.</AbstractText>Thirty-four patients of nonspecific ECG without structural heart disease were eligible for this study. All patients were referred for evaluation of syncopal episodes and/or cardiac arrest and/or frequent episodes of ventricular premature contractions. We assessed the correlation between baseline VLP and the alteration to a drug-induced type-1 Brugada ECG, and also evaluated the diagnostic accuracy of positive VLP in normal ECG subjects for the appearance of a drug-induced type-1 Brugada ECG.</AbstractText>Twenty-one patients presented positive VLP and 13 patients showed negative VLP. Parameters of VLP (fQRSd, RMS(40), LAS(40)) presented significant correlation with the alteration to a type-1 ECG by pilsicainide. VLP demonstrated high sensitivity and negative predictive value for the prediction of type-1 Brugada ECG. Furthermore, in their follow-up, at least two cases of ventricular fibrillation were recognized in 21 of positive VLP patients with apparently normal ECGs.</AbstractText>VLP in apparently normal ECG can predict the alteration to a drug-induced type-1 Brugada ECG and unmask the patients at risk.</AbstractText> |
6,088 | Primary and secondary prevention of ventricular arrhythmias in dilated cardiomyopathy: nonsustained, sustained, and incessant. | The occurrence of ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy (DCM) who are treated with an implantable cardioverter-defibrillator (ICD) for primary or secondary prevention is not fully understood. In this nonrandomized, two-centre, observational study we analyzed the occurrence of ventricular arrhythmias in a total of 105 DCM patients (age, 53 +/- 13 years) treated with an ICD. Fifty-one patients with a left ventricular ejection fraction <or= 35% did not have prior sustained ventricular arrhythmias (primary prevention). The secondary prevention group consisted of 54 patients with documented sustained ventricular tachycardia (n = 25) or aborted sudden cardiac death (n = 29). During 32 +/- 7 months follow-up the number of patients with appropriate defibrillator therapies (n = 51) was comparable between the two groups (HR 0.79, 95% CI 0.454 to 1.361, P = 0.389). Importantly, less primary prevention patients experienced appropriate ICD shocks for any arrhythmic event (HR 0.35, 95% CI 0.186 to 0.777, P = 0.008), as well as appropriate ICD shocks for ventricular fibrillation (HR 0.31, 95% CI 0.167 to 0.737, P = 0.006). In contrast, antitachycardia pacing was more often observed in the primary prevention group (HR 2.75, 95% CI 1.031 to 6.238, P = 0.043). Two primary prevention and 6 secondary prevention patients received multiple ICD therapies in consequence of incessant ventricular tachycardia. The characteristics of ventricular arrhythmias in patients with DCM who are treated with an ICD for primary or secondary prevention vary according to the underlying indication. Therefore, different device programming according to the patient's history might improve ventricular tachyarrhythmia management. |
6,089 | [Efficacy and safety of implantable cardioverter defibrillator avoiding routine defibrillation threshold testing]. | To evaluate the efficacy and safety of implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy-defibrillators (CRT-D) avoiding defibrillation threshold (DFT) testing when treating ventricular tachycardia (VT) or ventricular fibrillation (VF).</AbstractText>We analyzed a continuous database of the 21 patients who had avoided DFT during ICD implantation from Oct. 1999 to Aug. 2008. Follow-up data were completed and analyzed in the 21 patients with ICD implantation.</AbstractText>ICDs were implanted successfully in 17 patients with VT or VF, and CRT-D were implanted successfully in 4 myocardiopathy patients with severe heart failure who avoided DFT during ICD or CRT-D implantation. Eight patients accepted DFT 1 week later, VT or VF was not induced in 3 patients (37.5%). During the mean follow-up of 1 approximately 7 (4.2+/-1.9) years, malignant ventricular arrythmia was recorded in 16 patients. Among them, 89 episodes were successfully terminated by defbrillation (100%), 120 VT events were terminated by the first run of antitachycardia pacing (51.1%) and 22 by low energy cardioversion (59.2%). All patients took antiarrhycardia drugs after ICD or CRT-D implantation. No patient died from malignant ventricular arrythmia during the follow-up.</AbstractText>No application of routine DFT may avoid complications associated with DFT during ICD or CRT-D implantation. ICD or CRT-D implantation may effectively treat fatal ventricular tachyarrhythmias and prevent sudden cardiac death.</AbstractText> |
6,090 | Synergistic electrophysiologic and antiarrhythmic effects of the combination of ranolazine and chronic amiodarone in canine atria. | Amiodarone and ranolazine have been characterized as inactivated- and activated-state blockers of cardiac sodium channel current (I(Na)), respectively, and shown to cause atrial-selective depression of I(Na)-related parameters. This study tests the hypothesis that their combined actions synergistically depress I(Na)-dependent parameters in atria but not ventricles.</AbstractText>The effects of acute ranolazine (5 to 10 micromol/L) were studied in coronary-perfused right atrial and left ventricular wedge preparations and superfused left atrial pulmonary vein sleeves isolated from chronic amiodarone-treated (40 mg/kg daily for 6 weeks) and untreated dogs. Floating and standard microelectrode techniques were used to record transmembrane action potentials. When studied separately, acute ranolazine and chronic amiodarone caused atrial-predominant depression of I(Na)-dependent parameters. Ranolazine produced a much greater reduction in V(max) and much greater increase in diastolic threshold of excitation and effective refractory period in atrial preparations isolated from amiodarone-treated versus untreated dogs, leading to a marked increase in postrepolarization refractoriness. The drug combination effectively suppressed triggered activity in pulmonary vein sleeves but produced relatively small changes in I(Na)-dependent parameters in the ventricle. Acetylcholine (0.5 micromol/L) and burst pacing induced atrial fibrillation in 100% of control atria, 75% of ranolazine-treated (5 micromol/L) atria, 16% of atria from amiodarone-treated dogs, and in 0% of atria from amiodarone-treated dogs exposed to 5 micromol/L ranolazine.</AbstractText>The combination of chronic amiodarone and acute ranolazine produces a synergistic use-dependent depression of I(Na)-dependent parameters in isolated canine atria, leading to a potent effect of the drug combination to prevent the induction of atrial fibrillation.</AbstractText> |
6,091 | T wave oversensing and low percentage of biventricular pacing in cardiac resynchronization therapy. | The success of cardiac resynchronization therapy (CRT) depends on a high percentage of ventricular pacing. We present the electrocardiography and electrograms of a patient who underwent an implantable cardioverter-defibrillator (ICD) with CRT implantation showing a low percentage of ventricular pacing as a result of T wave oversensing of paced QRS. The patient showed no clinical improvement. We suggest finding a good sensitivity of F waves in induced ventricular fibrillation during ICD implantation in order to overcome the harm of possible oversensing. |
6,092 | Therapy with an implantable cardioverter defibrillator (ICD) in patients with coronary artery disease and dilated cardiomyopathy: benefits and disadvantages. | Contemporary guidelines refer to ICD implantation in patients who experienced ventricular tachycardia or fibrillation as secondary prevention, and in well-defined high risk groups as primary prevention. Randomised studies were performed in patients with coronary artery disease and in non-ischaemic cardiopathies, chiefly dilated cardiomyopathy. After four years' follow-up the absolute risk reduction was some 10% in secondary prevention and 8-20% in primary prevention, depending on the patient population. As only approx. 50% of ICD patients will receive appropriate therapies during long-term follow-up, reasonable risk stratification is crucial. However, apart from ejection fraction of <35%, all other echo- or electrocardiographic factors studied have thus far failed to have significant impact to determine risk in advance. In a retrospective analysis comorbidities such as advanced age, renal failure and atrial fibrillation have been shown to influence the effect of an ICD. During long term follow-up inappropriate shocks, lead complications, premature battery depletion and anxiety are some of the most significant problems for an ICD patient. |
6,093 | Therapeutic mild hypothermia improves outcome after out-of-hospital cardiac arrest. | Purpose. Therapeutic mild hypothermia (TMH) is indicated for comatose survivors of an out-ofhospital cardiac arrest (OHCA) to improve general outcome. Although widely used, there are not many reports on its use on a critical care unit (CCU) or on the comparison of cooling methods.Methods. In a retrospective analysis covering January 2005 to December 2006, 75 consecutive comatose subjects post-OHCA due to ventricular fibrillation and nonventricular fibrillation rhythms (asystole/pulseless electrical activity) were studied in a single tertiary PCI centre. Subjects treated with conventional post-resuscitation care without TMH served as controls (n=26; Jan 2005-Sep 2005). Outcome from controls at hospital discharge was compared with subjects treated with TMH (n=49; Oct 2005-Dec 2006). During the study period, TMH was induced by either external (n=25; Oct 2005-Feb 2006) or endovascular (n=24; Mar 2006-Dec 2006) approach.Results. Besides more females in the control group, there were no major differences in baseline characteristics present between all groups. TMH improved survival (OR 0.36 [0.13-0.95], p<0.05) and neurological outcome (OR 0.23 [0.07-0.70], p<0.01). After subanalysis, TMH-improved outcome did not differ between the two cooling methods used. However, the times to reach TMH and normothermia were shorter with the endovascular approach.Conclusion. TMH induced on a CCU improves survival and neurological outcome after post-OHCA coma. TMH by endovascular approach was more feasible compared with external cooling, but the two cooling methods did not result in a different outcome. (Neth Heart J 2009;17:378-84.). |
6,094 | The relationship between chronic atrial fibrillation and reduced pulmonary function in cases of preserved left ventricular systolic function. | The purpose of this study was to investigate the relationship between chronic atrial fibrillation (AF) and reduced pulmonary function.</AbstractText>Eighty-six chronic AF patients who were enrolled from annual health examination programs were studied using echocardiography and pulmonary function tests (PFT). Echocardiography and PFT matched for age, gender, and year performed were selected by the control group who had normal sinus rhythms. Patients with ejection fractions <50%, valvular heart disease, or ischemic heart disease were excluded.</AbstractText>In the chronic AF patients, the forced expiratory volume at one second (FEV(1)), FEV1%, and FEV(1)/forced vital capacity (FVC) were significantly reduced, and the right ventricular systolic pressure was significantly increased. Episodes of heart failure were more frequently associated with the chronic AF patients than the controls. In particular, the FEV1% had the most meaningful relationship to chronic AF after an adjustment for cardiovascular risk factors {p=0.003, Exp (B)=0.978, 95% confidence interval (CI):0.963-0.993}.</AbstractText>Reduced FEV1%, which represents the severity of airway obstruction, was associated with chronic AF, and the greater the pulmonary function impairment, the greater the co-existence with AF and congestive heart failure in those with preserved left ventricular systolic function.</AbstractText> |
6,095 | The influence of the left ventricular geometry on the left atrial size and left ventricular filling pressure in hypertensive patients, as assessed by echocardiography. | It is not well understood whether the left ventricular geometry is associated with such diastolic parameters as the left atrial volume and the left ventricular filling pressure, as assessed by the Doppler indices. Accordingly, this study aimed to evaluate the influence of the left ventricular geometry on the left atrial volume and the left ventricular filling pressure, as assessed by the Doppler indices.</AbstractText>181 patients (mean age: 63+/-9 years old, 62 males) with hypertension were included for echocardiographic analysis. The hypertensive patients were classified into four groups according to the left ventricular mass index and the relative wall thickness: normal geometry, concentric remodeling, eccentric hypertrophy and concentric hypertrophy. We excluded all the individuals with established cardiovascular disease, atrial fibrillation, significant aortic and/or mitral valve disease, or an ejection fraction <50%.</AbstractText>By definition, the left ventricular mass was increased in the patients with eccentric and concentric hypertrophy. Both the left ventricular end-systolic diameter and the left ventricular end-diastolic diameter were reduced in the concentric remodeling group, whereas the left ventricular end-systolic diameter and the left ventricular end-diastolic diameter were increased in the eccentric and concentric hypertrophy groups. Compared with the patients with normal geometry, the patients with eccentric and concentric hypertrophy demonstrated a significant higher value for the left atrial volume index. The ratio of the transmitral inflow velocity to the mitral annular velocity (E/E') showed a stepwise increase from the patients with normal geometry to the patients with concentric remodeling, and then to the patients with eccentric and concentric hypertrophy.</AbstractText>This study demonstrates that in a patient population with hypertension and who are without systolic dysfunction, the left atrial volume index and the E/E' demonstrated a progressive worsening of the left ventricular diastolic function from patients with normal geometry to the patients with concentric remodeling, and then to the patients with eccentric and concentric hypertrophy.</AbstractText> |
6,096 | Left atrial infarction: a case report and review of the literature. | The majority of cardiac related deaths are due to ischemic heart disease, with the most common clinical scenario being severe coronary artery atherosclerosis resulting in left ventricular myocardial infarction. However, infarction of other cardiac chambers does occur, and often has specific clinical associations. We report a case of a 70-year-old man who suffered from left atrial infarction that resulted in a transmural rupture of his left atrium. The patient had a history of rheumatic heart disease, mitral valve stenosis, and severe atherosclerotic coronary artery disease. Four days before death, he underwent mitral valve replacement and left circumflex coronary artery bypass. Two days later, he developed atrial fibrillation. On the day of death, he had decreased mental status, questionable seizure activity, hematemesis, ventricular tachycardia, and eventually asystole. At autopsy, he had significant hemopericardium with a fibrinous pericarditis and bilateral hemothoraces (total blood volume: 1250 mL). A 0.1 to 0.2 cm left atrial transmural defect was identified. The prosthetic mitral valve was free of vegetations, and completely intact. Similarly, the left circumflex artery bypass graft was completely patent and unremarkable. Severe calcific atherosclerosis was of his native left circumflex and left main coronary arteries. Microscopic examination revealed acute myocardial infarction of the left atrium at the rupture site. The anatomy of atrial circulation as well as the pathology and consequences of atrial infarction are discussed. |
6,097 | Reliability of an external loop recorder for automatic recognition and transtelephonic ECG transmission of atrial fibrillation. | In order to test a newly developed algorithm for detecting atrial fibrillation in clinical practice, we carried out parallel recordings using a conventional 24-h electrocardiogram (ECG) monitor and telemonitoring with an external loop recorder. Recordings were made in 24 patients with persistent atrial fibrillation and in another 24 patients with sinus rhythm. Atrial fibrillation was detected immediately in 23 of 24 patients with persistent atrial fibrillation and 20 min after fitting the single-channel loop recorder in the 24th patient (sensitivity 100%). On average, 3.1 false positives (i.e. detection of an episode, including the end or beginning of atrial fibrillation) were transmitted per patient. The sensitivity of the algorithms for automatically detecting bradycardiac and tachycardiac atrial fibrillation was also high. In 12 of 24 patients with sinus rhythm, false-positive tele-ECGs were transmitted. These were caused by supraventricular or ventricular extrasystoles and by sinus arrhythmias or sinoatrial (SA) blocks. The external loop recorder was very effective at detecting paroxysmal atrial fibrillation. Possible indications for the clinical use of this recorder include, in addition to diagnosis, monitoring patients for atrial fibrillation recurrence after cardioversion or catheter ablation. |
6,098 | QTc prolongation during therapeutic hypothermia: are we giving it the attention it deserves? | Therapeutic hypothermia (TH) is used in neuroprotection following cardiac arrest due to ventricular tachycardia (VT) and ventricular fibrillation (VF). Accidental hypothermia is itself known to cause prolongation of the corrected QT interval (QTc). QTc prolongation can cause polymorphic VT and VF. If this also occurs in TH, it may induce refibrillation. We investigated the effect of TH on the QTc interval.</AbstractText>Prospective case series of all patients undergoing TH following cardiac arrest following VT/VF at our hospital between July 2008 and January 2009. We studied the effect of temperature on QTc. All electrocardiograms (ECGs) undertaken during TH were studied and compared with the ECG prior to this. Four patients underwent TH. A total of 10 ECGs were undertaken during TH. The QTc was normal prior to TH. It became prolonged (>460 ms) in all cases during TH and normalized after cessation of TH, apart from Patient 4 who did not have an ECG post-TH since she died from cardiogenic shock. There was a negative correlation between temperature and QTc (Pearson's correlation coefficient, r= -0.71).</AbstractText>Our series illustrates QTc prolongation during TH. This carries potential for refibrillation. Guidelines on ECG monitoring during TH are needed, especially since hypothermic myocardium is intrinsically prone to arrhythmias and commonly used antiarrythmic drugs such as amiodarone can prolong the QTc.</AbstractText> |
6,099 | Vernakalant hydrochloride for the rapid conversion of atrial fibrillation after cardiac surgery: a randomized, double-blind, placebo-controlled trial. | Postoperative atrial arrhythmias are common and are associated with considerable morbidity. This study was designed to evaluate the efficacy and safety of vernakalant for the conversion of atrial fibrillation (AF) or atrial flutter (AFL) after cardiac surgery.</AbstractText>This was a prospective, randomized, double-blind, placebo-controlled trial of vernakalant for the conversion of AF or AFL after coronary artery bypass graft, valvular surgery, or both. Patients were randomly assigned 2:1 to receive a 10-minute infusion of 3 mg/kg vernakalant or placebo. If AF or AFL was present after a 15-minute observation period, then a second 10-minute infusion of 2 mg/kg vernakalant or placebo was given. The primary end point was the conversion of postcardiac surgery AF or AFL to sinus rhythm within 90 minutes of dosing. In patients with AF, 47 of 100 (47%) who received vernakalant converted to SR compared with 7 of 50 (14%) patients who received placebo (P<0.001). The median time to conversion was 12 minutes. Vernakalant was not effective in converting postoperative AFL to sinus rhythm. Two serious adverse events occurred within 24 hours of vernakalant administration (hypotension and complete atrioventricular block). There were no cases of torsades de pointes, sustained ventricular tachycardia, or ventricular fibrillation. There were no deaths.</AbstractText>Vernakalant was safe and effective in the rapid conversion of AF to sinus rhythm in patients who had AF after cardiac surgery.</AbstractText>clinicaltrials.gov. Identifier: NCT00125320.</AbstractText> |
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