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1,100 | Clinical assessment and management of patients with implanted cardioverter-defibrillators presenting to nonelectrophysiologists. | All physicians increasingly will encounter patients who have implanted cardioverter-defibrillators (ICDs) for protection from ventricular arrhythmias. This advisory provides a concise summary relevant to the assessment and management of patients with ICDs, including those who present to primary care or emergency department physicians with symptoms suggesting arrhythmia or ICD malfunction and those who require cardiac or surgical procedures. |
1,101 | Cardioprotection by epsilon-protein kinase C activation from ischemia: continuous delivery and antiarrhythmic effect of an epsilon-protein kinase C-activating peptide. | We previously showed that a selective activator peptide of epsilon-protein kinase C (PKC), psi(epsilon)RACK, conferred cardioprotection against ischemia-reperfusion when delivered ex vivo before the ischemic event. Here, we tested whether in vivo continuous systemic delivery of psi(epsilon)RACK confers sustained cardioprotection against ischemia-reperfusion in isolated mouse hearts and whether psi(epsilon)RACK treatment reduces infarct size or lethal arrhythmias in porcine hearts in vivo.</AbstractText>After psi(epsilon)RACK was systemically administered in mice either acutely or continuously, hearts were subjected to ischemia-reperfusion in an isolated perfused model. Whereas psi(epsilon)RACK-induced cardioprotection lasted 1 hour after a single intraperitoneal injection, continuous treatment with psi(epsilon)RACK induced a sustained preconditioned state during the 10 days of delivery. There was no desensitization to the therapeutic effect, no downregulation of epsilonPKC, and no adverse effects after sustained psi(epsilon)RACK delivery. Porcine hearts were subjected to ischemia-reperfusion in vivo, and psi(epsilon)RACK was administered by intracoronary injection during the first 10 minutes of ischemia. psi(epsilon)RACK treatment reduced infarct size (34+/-2% versus 14+/-1%, control versus psi(epsilon)RACK) and resulted in fewer cases of ventricular fibrillation during ischemia-reperfusion (87.5% versus 50%, control versus psi(epsilon)RACK).</AbstractText>The epsilonPKC activator psi(epsilon)RACK induced cardioprotection both in vivo and ex vivo, reduced the incidence of lethal arrhythmia during ischemia-reperfusion, and did not cause desensitization or downregulation of epsilonPKC after sustained delivery. Thus, psi(epsilon)RACK may be useful for patients with ischemic heart disease. In addition, the psi(epsilon)RACK peptide should be a useful pharmacological agent for animal studies in which systemic and sustained modulation of epsilonPKC in vivo is needed.</AbstractText> |
1,102 | Azd7009: a new antiarrhythmic drug with predominant effects on the atria effectively terminates and prevents reinduction of atrial fibrillation and flutter in the sterile pericarditis model. | We tested the hypothesis that AZD7009 terminates induced atrial fibrillation (AF) and flutter (AFL) and prevents their reinduction, and that effects on refractoriness, conduction, and excitability are predominantly on the atria.</AbstractText>Thirty-eight electrophysiologic studies were performed during AZD7009 infusion in 11 dogs with sterile pericarditis. The effects of AZD7009 on refractoriness, conduction, and capture threshold were studied and its antiarrhythmic efficacy tested. Simultaneous multisite biatrial mapping was performed in 7 dogs to assess arrhythmia termination. AZD7009 prolonged arrhythmia cycle length (CL) from 121 +/- 7.8 to 157 +/- 9.7 msec (P < 0.001) before terminating 23 of 23 AF/AFL episodes. Mapping demonstrated that AF/AFL CL prolonged and then terminated in area(s) of slow conduction in a reentrant circuit. Arrhythmia reinduction failed in 19 of 20 attempts. At 400-msec CL, atrial and ventricular refractoriness and QT interval increased 33%, 17% (P < 0.001 vs atrial refractoriness), and 9%, respectively. Atrial capture threshold increased in a CL-dependent manner: 1.8 +/- 0.3 to 2.2 +/- 0.3 mA (CL 400 msec); 2.1 +/- 0.3 to 2.8 +/- 0.5 mA (CL 300 msec), and 2.2 +/- 0.3 to 5.3 +/- 0.8 mA (CL 200 msec). Only minor nonsignificant changes occurred in the ventricles: 0.95 +/- 0.05 to 0.98 +/- 0.06 mA (CL 400 msec), and 1.14 +/- 0.12 to 1.16 +/- 0.13 mA (CL 333 msec). Atrial conduction time increased 8 +/- 1.4 msec (CL 400 msec), 8.3 +/- 1.5 msec (CL 300 msec), and 13.2 +/- 1.6 msec (CL 200 msec, all P < 0.001), but ventricular conduction time was unchanged.</AbstractText>AZD7009 is highly efficacious in terminating AF/AFL and preventing reinduction in this model. It exhibits marked effects on atrial electrophysiology but has only modest effects on the ventricle.</AbstractText> |
1,103 | Coexistence of two types of ventricular fibrillation during acute regional ischemia in rabbit ventricle. | We previously reported that a normal ventricle can demonstrate two types of ventricular fibrillation (VF), depending on the underlying electrophysiologic characteristics at the time of VF induction. We hypothesize that the two types of VF can coexist in acutely ischemic ventricles.</AbstractText>Optical mapping studies were performed with di-4ANEPPS in 15 Langendorff-perfused rabbit hearts. Coronary artery branches were ligated to create regional ischemia in 10 hearts. Action potential duration measured to 50% repolarization (APD50) during ischemia showed an area with uniformly shortened APD50 (zone 1), an area with normal or lengthened APD50 (zone 3), and an area in between with an APD50 gradient (zone 2). Ischemia flattened APD restitution (APDR) slope and reduced conduction velocity in zone 1, creating a condition for type II VF. APDR steepened and the conduction velocity changed little in the nonischemic zone (zone 3), creating a condition for type I VF. During induced VF, the dominant frequency in zones 2 and 3 progressively increased after ischemia onset. The dominant frequency in zone 1 (ischemic zone) first decreased and then slightly increased but typically remained less than the dominant frequency in zone 3. The number of wavebreaks increased with time in all three zones (baseline: 4.3 +/- 1.5; 30 min: 11.7 +/- 5.6; 60 min: 15.6 +/- 11 per frame; P < 0.01).</AbstractText>Two types of VF can coexist during acute regional ischemia. Both ischemic and nonischemic regions develop proarrhythmic changes during regional ischemia, thus contributing to increased ventricular vulnerability to VF and sudden death during acute coronary occlusion.</AbstractText> |
1,104 | Preoperative electrocardiographic risk assessment of atrial fibrillation after coronary artery bypass grafting. | This study evaluated the role of surface ECG in assessment of risk of new-onset atrial fibrillation (AF) after coronary artery bypass grafting surgery (CABG).</AbstractText>One hundred fifty-one patients (126 men and 25 women; age 65 +/- 10 years) without a history of AF undergoing primary elective and isolated CABG were studied. Standard 12-lead ECGs and P wave signal-averaged ECG (PSAE) were recorded 24 hours before CABG using a MAC VU ECG recorder. In addition to routine ECG measurements, two P wave (P wave complexity ratio [pCR]; P wave morphology dispersion [PMD]) and six T wave morphology descriptors (total cosine R to T [TCRT]; T wave morphology dispersion of ascending and descending part of the T wave [aTMD and dTMD], and others), and three PSAE indices (filtered P wave duration [PD]; root mean square voltage of terminal 20 msec of averaged P wave [RMS20]; and integral of P wave [Pi]) were investigated. During a mean hospital stay of 7.3 +/- 6.2 days after CABG, 40 (26%) patients developed AF (AF group) and 111 remained AF-free (no AF group). AF patients were older (69 +/- 9 years vs 64 +/- 10 years, P = 0.005). PD (135 +/- 9 msec vs 133 +/- 12 msec, P = NS) and RMS20 (4.5 +/- 1.7 microV vs 4.0 +/- 1.6 microV, P = NS) in AF were similar to that in no AF, whereas Pi was significantly increased in AF (757 +/- 230 microVmsec vs 659 +/- 206 microVmsec, P = 0.007). Both pCR (32 +/- 11 vs 27 +/- 10) and PMD (31.5 +/- 14.0 vs 26.4 +/- 12.3) were significantly greater in AF (P = 0.012 and 0.048, respectively). TCRT (0.028 +/- 0.596 vs 0.310 +/- 0.542, P = 0.009) and dTMD (0.63 +/- 0.03 vs 0.64 +/- 0.02, P = 0.004) were significantly reduced in AF compared with no AF. Measurements of aTMD and three other T wave descriptors were similar in AF and no AF. Significant variables by univariate analysis, including advanced age (P = 0.014), impaired left ventricular function (P = 0.02), greater Pi (P = 0.012), and lower TCRT (P = 0.007) or dTMD, were entered into multiple logistic regression models. Increased Pi (P = 0.038), reduced TCRT (P = 0.040), and lower dTMD (P = 0.014) predicted AF after CABG independently. In patients <70 years, a linear combination of increased pCR and lower TCRT separated AF and no AF with a sensitivity of 74% and specificity of 62% (P = 0.005).</AbstractText>ECG assessment identifies patients vulnerable to AF after CABG. Combination of ECG parameters assessed preoperatively may play an important role in predicting new-onset AF after CABG.</AbstractText> |
1,105 | Spatial dispersion of action potential duration restitution kinetics is associated with induction of ventricular tachycardia/fibrillation in humans. | Action potential duration restitution (APDR) plays a role in initiation and maintenance of ventricular tachycardia (VT)/ventricular fibrillation (VF). We hypothesized that the steeply sloped APDR and its spatial heterogeneity contribute to VT/VF inducibility in patients with ventricular arrhythmia.</AbstractText>After programmed ventricular stimulation (PVS) for evaluation of clinically documented VT, patients (n = 20, 15 male, age 52.5 +/- 9.5 years) were divided into two groups: inducible sustained VT/VF (IVT, n = 10) and noninducible VT/VF (NVT, n = 10). Data were compared with the corresponding results obtained from normal controls (C, n = 10). Right ventricular (RV) monophasic action potential duration at 90% repolarization (APD90) and ventricular effective refractory period (VERP) in the right ventricular apex (RVA) and right ventricular outflow tract (RVOT) were determined. APDR was acquired by scanning diastole with premature ventricular beats during a pacing cycle length of 600 msec (S1-S2) in all patients and by rapid pacing at the cycle lengths that induced APD alternans in three patients. Maximal slopes (Smax) of the APDR curves and DeltaAPD90 (APD90 at S2 400 ms - APD90 at the shortest S2) were measured. VERP and APD90 at each RV site did not differ among the three groups. Smax obtained by S1-S2 (1.6 +/- 0.6) did not differ from Smax obtained by rapid pacing (1.2 +/- 0.7), with a significant correlation noted between these values (r = 0.92, P < 0.01). The IVT group had a higher spatial dispersion of Smax (Smax at RVOT - Smax at RVA) compared to the C group (P < 0.05), with no difference between the NVT group and the IVT or C groups. The IVT group had a higher spatial dispersion of DeltaAPD90 compared to the NVT and C groups (P < 0.01, respectively). Smax at the RVOT (2.7 +/- 1.9) was steeper than that at the RVA (1.9 +/- 1.2, P < 0.05). Inducibility of sustained VT/VF was greater at the RVOT (83.3%) than at the RVA (50.0%, P < 0.05).</AbstractText>In patients with ventricular arrhythmia, VT/VF is highly inducible under conditions of greater spatial dispersion of ventricular refractoriness and APDR.</AbstractText> |
1,106 | [Value of memory functions in implantable prostheses]. | The development of memory functions with memorised electrogrammes is one of the most important technical advances in cardiac pacemakers and defibrillators. These memory functions are very useful in the management of patients with implanted prostheses. In the case of defibrillators, the memory allows evaluation and validation of appropriate treatments (shock or asymptomatic antitachycardia stimulation) or inappropriate function. The memory can also help assess the efficacy of complementary antiarrhythmic therapy or radiofrequency ablation. The incorporation of memory functions in pacemakers is more recent but no less useful. The latest generation of pacemakers have not only a therapeutic but also a diagnostic role with respect to atrial and ventricular arrhythmias. They can lead to the prescription of an antiarrhythmic or anticoagulant drug in cases of sustained atrial fibrillation confirmed by the memorised electrogrammes. The memory function is also a great aid in reprogramming stimulators in cases of overdetection (V-A cross talk). They may also be activated by the patient in cases of sporadic paroxysmal symptoms. The latest development is that of a purely diagnostic prosthesis: the implantable Holter, whose main indication is in the investigation of unexplained syncope. |
1,107 | [Implantable defibrillator and ventricular resynchronisation]. | Ventricular resynchronisation by pacing, introduced at the end of the 1990s, has revolutionised the management of advanced chronic cardiac failure. Its value in the reduction of haemodynamic mortality has been demonstrated in the latest studies. However, despite these decisive advances, patients with cardiac failure continue to have a high incidence of sudden death which, classically, according to its stage of progression, represents 28 to 68% of deaths in this condition. The implantable automatic defibrillator (IAD) has been shown to be effective in preventing sudden death, mainly in patients with severe left ventricular dysfunction. Based on these data, and in a context of rapid technological progress, devices capable of both defibrillating and resylchronising the heart have been introduced. The problems experienced at the beginning of their utilisation, mainly related to "double-counting" of left and right ventricular electrical activation have been resolved and the method is now technically feasible. A complication rate >10%, mainly due to the implantation of the left heart catheter, continues to bear witness to the difficulties of this technique and to the severity of the condition of patients referred for the treatment. The COMPANION trial has shown a greater reduction in mortality of patients treated by resynchronisation associated with IAD compared with resynchronisation alone or medical therapy in > or = Stage III cardiac failure. The SCD-HeFT trial has recently demonstrated that the primary prevention of global mortality by the IAD is effective in cardiac failure irrespective of the underlying cardiac pathology, especially in functional Stage II. These results should lead to significant increase in the indications for implantation of devices capable of both resynchronisation and defibrillation. However, the obvious problems of cost associated with the difficulty of the technique mean that a systematic attitude cannot be recommended. A case-by-case discussion has its place but the causal cardiac disease, ischaemic or not, does not seem to be a determining factor. |
1,108 | [Role of cardiac resynchronisation in the treatment of cardiac failure]. | For 10 years cardiac resynchronisation has seen considerable development, as much on the technological side as at the level of its scientific validation. Several prospective studies have shown the functional benefits of cardiac resynchronisation in a selected population of refractory cardiac failure patients with improvement in symptoms, exercise tolerance and quality of life. Equally, cardiac resynchronisation allows a significant reduction in hospital episodes for cardiac failure and also has a beneficial effect on left ventricular inverse remodelling. Finally, the first results of morbidity/mortality trials are very encouraging with a significant reduction in overall mortality at one year in the COMPANION study with the biventricular defibrillator. However, numerous important, unresolved questions remain such as the problem of non-responders and thus patient selection, or such as the place of cardiac resynchronisation in patients with permanent atrial fibrillation. The choice of the type of implantable prosthesis (pacemaker or biventricular defibrillator) and the choice of the mode of pacing (biventricular or solely left ventricular) are still under discussion. New indications for cardiac resynchronisation could be seen next, for example such as the optimisation of stimulation mode in already paced patients or "systematic" biventricular pacing in patients with a conventional indication for pacing..... In 2004, cardiac resynchronisation must be considered as an effective adjuvant therapy in cardiac failure patients refractory to optimal medical treatment with left ventricular dysfunction and intraventricular conduction disorders. |
1,109 | [The role of cardiac pacing in the treatment of atrial arrhythmias]. | The role of cardiac pacing in the treatment of atrial arrhythmias can be analysed from the angle of prevention or treatment in a strategy of rhythm control or heart rate control. From the heart rate control viewpoint, "ablate and place" is a validated method, especially in terms of mortality based on the results of large registers, in cases of uncontrolled ventricular rhythms causing symptoms or left ventricular dysfunction. In a strategy of rhythm control, the theoretical bases of prevention of atrial fibrillation (AF) by atrial pacing are convincing but the clinical results of different prospective clinical trials, though encouraging, do not provide formal proof of the efficacy of preventive pacing. Permanent 100% atrial pacing remains the objective which has led to the development of many algorithms evaluated in the ADOPT, AF Therapy, PIPAF, ATTEST...trials, with contradictory results. The choice of atrial pacing site seems to be a determining factor for the success of the method with better results seemingly with the high or low septal positions. The results of the OASES trial support this hypothesis but they were not confirmed by the ASPECT trial. An interesting observation was made in the PIPAF and a new Danish trial on the deleterious effects of ventricular capture when not required which is the rule in patients paced for brady-tachycardia syndromes. As for the role of anti-tachycardia pacing, the technique remains to be validated. Perhaps, the association of different techniques evaluated--the site of pacing, the prevention algorithms, respect of the ventricular rhythms, reduction by anti-tachycardia stimulation--will provide multifunction devices capable of best managing atrial arrhythmias which do not require "curative" therapy, and in particular, endocavitary ablation. In practice, it is generally when faced with brady-tachycardia syndromes that the question of the preventive role of pacing is raised. The problem is to choose the site of stimulation and the most appropriate pacing device in the light of current knowledge. |
1,110 | [New anti-arrhythmics--hope or disappointment?]. | The new anti-arrhythmic agents studied in the last decade have mostly come from research orientated towards determining the compounds which block the electrical currents implicated in the process of repolarisation (class III action). To this must be added dronedarone, which is related to amiodarone and as such displays the 4 classes of anti-arrhythmic properties. Pure class III agents prolong the cardiac action potential and therefore the refractory period and QT interval. The conduction velocity is unaltered. These agents act best on re-entry arrhythmias. Dofetilide is a prototype. The class III action is linked to blockade of the Ikr current and can paradoxically lower it at increased heart rates. Dofelitide has not shown a harmful effect on the survival of high risk ischaemic patients. The conversion of atrial tachyarrhythmias into sinus rhythm can be obtained in one to two thirds of cases. As for the prevention of these arrhythmias, its success rate can exceed 60%. On the other hand, the occurrence of torsades de pointe is in the order of 3%, justifying the initiation of treatment under hospital conditions. Ibutilide acts by blocking the Ikr and INa-s currents. Used only intravenously, this agent is capable of converting back to sinus rhythm a third of atrial fibrillation episodes and two thirds of flutter. The risk of torsades de pointe is 3.5% so this treatment must also be commenced in the hospital setting. Azimilide blocks multiple Iks channels as well as Ikr, Ica and Ina. The electrophysiological effect is sustained at rapid heart rates. When evaluated in patients with paroxysmal atrial fibrillation, azimide prolonged the interval until recurrence, associated with an excellent tolerance (torsades de pointe in 0.55% of cases). In a survival study, azimide demonstrated a neutral effect in high risk subjects with diminished ejection fraction and sinusal variability. Unlike the previous agents, dronedarone is a benzofurane with a similar structure to amiodarone but without iodine. The 800 mg dose is associated with the best risk-benefit ratio. In patients with left ventricular dysfunction, the administration of this agent has been associated with excess mortality. Two recent studies on the prevention of atrial fibrillation have demonstrated that dronedarone is moderately effective with an excellent general tolerance. |
1,111 | New indications for the use of therapeutic hypothermia. | Randomised, controlled trials of therapeutic hypothermia have demonstrated improved outcomes after out-of-hospital cardiac arrest, where the initial cardiac rhythm was ventricular fibrillation. This therapy is now endorsed by the International Liaison Committee on Resuscitation. The role of therapeutic hypothermia in patients with anoxic neurological injury due to stroke, spinal cord injury or asphyxial cardiac arrest is uncertain. However, given the strong theoretical benefit and the minimal adverse side-effects, it is reasonable for clinicians to consider the use of therapeutic hypothermia in such cases. |
1,112 | Transplantation using hearts from primary pulmonary hypertensive donors for recipients with a high pulmonary vascular resistance. | Transplantation for patients with a high pulmonary vascular resistance (PVR) carries an increased risk of mortality and right heart failure following heart transplantation and continues to be a major problem. We evaluated the use of hearts from patients who underwent heart and lung transplantation for primary pulmonary hypertension (PPH) as part of a domino procedure because these hearts have hypertrophied right ventricles used to increased pulmonary pressures, but could have a compromised left ventricle or irreversible damage of the right ventricle.</AbstractText>We reviewed 12 patients with PVR >4 Wood units who underwent orthotopic heart transplantation between 1989 and 1998 using hearts from donors with PPH as part of a domino procedure.</AbstractText>We studied 10 men and 2 women, mean age 42.9 years. Mean PVR was 5.3 (range, 4-9) Wood units. Mean ischemia time was 85.3 minutes, and mean donor age was 32 years. Actuarial survival was 75% at 1 year and 75% at 5 years. In the early post-operative period, 3 patients had temporary arrhythmias, 2 required permanent pacemaker implantation, 1 had atrial fibrillation, and 1 had ventricular tachycardia that required defibrillator implantation. At a mean follow-up of 7.8 years, 2 patients had developed asymptomatic transplant coronary disease (both at 8.5 years after transplantation), 1 moderate and 1 very mild; the rest had none. Mean left ventricular ejection fraction at latest follow-up was 70.1% (range, 63%-78%). Right ventricular function assessed clinically and by echocardiography was adequate in the short and long term.</AbstractText>Our results suggest that heart and lung recipients with PPH can provide useful donor hearts to patients with increased PVR and that these hearts function well in the intermediate and long term.</AbstractText> |
1,113 | Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms. | The purpose of this randomized study was to investigate the performance of single- and dual-chamber tachyarrhythmia detection algorithms.</AbstractText>A proposed benefit of dual-chamber implantable cardioverter-defibrillators (ICDs) is improved specificity of tachyarrhythmia detection.</AbstractText>All ICD candidates received a dual-chamber ICD and were randomized to programmed single- or dual-chamber detection. Of 60 patients (47 male, age 58 +/- 14 years, left ventricular ejection fraction 30%), 29 had single-chamber and 31 had dual-chamber settings. The detection results were corrected for multiple episodes within a patient with the generalized estimating equations method.</AbstractText>A total of 653 spontaneous arrhythmia episodes (39 patients) were classified by the investigators; 391 episodes were ventricular tachyarrhythmia (32 patients). All episodes of ventricular tachyarrhythmias were appropriately detected in both settings. In 25 patients, 262 episodes of atrial tachyarrhythmias were recorded. Detection was inappropriate for 109 atrial tachyarrhythmia episodes (42%, 18 patients). Rejection of atrial tachyarrhythmias was not significantly different between both groups (p = 0.55). Episodes of atrial flutter/tachycardia were significantly more misclassified (p = 0.001). Overall, no significant difference in tachyarrhythmia detection (atrial and ventricular) between both settings was demonstrated (p = 0.77).</AbstractText>The applied detection criteria in dual-chamber devices do not offer benefits in the rejection of atrial tachyarrhythmias. Discrimination of atrial tachyarrhythmias with a stable atrioventricular relationship remains a challenge.</AbstractText> |
1,114 | Natriuretic peptides and the prevalence of congestive heart failure in patients with pacemakers. | The aim of the study was to investigate the diagnostic potential of natriuretic cardiac peptide measurement in the context of left ventricular dysfunction and comorbidities in a pacemaker population.</AbstractText>Ninety-five consecutive patients with pacemakers were included in the study. All patients underwent echocardiography and were asked to complete the Minnesota Living with Heart Failure Questionnaire (MLHFQ). Brain natriuretic peptide (BNP), N-terminal proatrial natriuretic peptide (N-ANP) and atrial natriuretic peptide levels in plasma were measured.</AbstractText>Twenty-six percent of patients had reduced systolic left ventricular function; only 16 patients had a history of congestive heart failure. BNP was abnormally elevated in 64%, N-BNP in 72% and N-ANP in 96% of patients. Both BNP (r = 0.30; P < 0.01) and N-ANP (r = 0.39; P < 0.0005) correlated with MLHFQ. The strongest correlation was found between N-ANP and the ejection fraction (r = 0.6; P < 0.0001). Patients were stratified in a high-risk group and a low risk-group according to their N-ANP (N-ANP > 5000 fmol L(-1); n = 63 and N-ANP < 5000 fmol L(-1), n = 32) and BNP levels (BNP > 400 pg mL(-1); n = 17 and BNP < 400 pg mL(-1), n = 78). N-ANP was correlated with hypertension (P < 0.003) and atrial fibrillation (P < 0.03), and BNP with mitral insufficiency (P < 0.002).</AbstractText>Cardiac natriuretic peptides are markedly elevated in the majority of patients with pacemakers. The prognostic significance of BNP and N-ANP in left ventricular dysfunction warrants close follow-up schedules.</AbstractText> |
1,115 | [Comparison of the anti-arrhythmic effects of matrine and berbamine with amiodarone and RP58866]. | To clarify mechanisms that the antiarrhythmic effects of matrine and berbamine are weaker than those of amiodarone and RP58866.</AbstractText>Experimental arrhythmic models were induced by aconitine, coronary artery ligation and electric stimulation in rats and rabbits. Whole-cell patch-clamp techniques were used to record IK1, IKr, IKs and Ito.</AbstractText>Matrine and berbamine significantly increased the dose of aconitine for induction of ventricular premature and ventricular tachycardia in rats, decreased the number of arrhythmias induced by coronary artery ligation in rats and increased ventricular fibrillation threshold (VFT) induced by electric stimulation in rabbits, but the anti-arrhythmic potency of matrine and berbamine was lower than that of amiodarone and RP58866. The inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866. The IC50 of matrine for IK1, IKr, IKs, Ito were (46 +/- 3), (32.9 +/- 1.2), (37 +/- 8) and (7.6 +/- 0.5) mol x L(-1), respectively. The IC50 of amiodarone for IK1, IKr, IKs, Ito were (21 +/- 5) , (3.7 +/- 0.7), (5.9 +/- 0.9) and (5.9 +/- 0.6) mol x L(-1), respectively.</AbstractText>The inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866, which might be the reason that the antiarrhythmic effects of matrine and berbamine were weaker than those of amiodarone and RP58866.</AbstractText> |
1,116 | [Out-of-hospital resuscitation in Israel 2000]. | The aim of the study was to evaluate the impact of pre-hospital cardio-pulmonary resuscitation, performed by mobile intensive cardiac care units of Magen David Adom (MDA) teams in the framework of a national survey conducted in the period February and March 2000. During the survey, MDA performed 539 resuscitations, 485 of which were performed by mobile intensive care units of MDA, and they constitute the study population of the present analysis. The average age of the patients was 70.5 years, and 68% were men. The mean response time of the mobile intensive care units was 10.3 minutes. In 14% of the cases, a bystander initiated basic cardiac life support before the arrival of the MDA team. Upon arrival of the resuscitation team, 242 patients (50%) had asystole, 19% ventricular tachycardia (VT)/ventricular fibrillation (VF), 13% pulseless electrical activity (PEA), and 18% had other severe arrhythmias. One hundred and ninety-nine patients (41%) were transferred alive to the hospital after successful resuscitation. Hospital summaries were obtained for 148 of these patients. The cause of cardiac arrest was cardiac in 64% of the cases and 48% of the patients who reached the hospital had a previous history of heart disease. Fifty-three patients (11%) were discharged alive from the hospital. Patients discharged alive were younger, more promptly resuscitated, 78% had a cardiac cause of death and 38% of them were in ventricular tachycardia/fibrillation when first seen by the resuscitation team. The rate of successful resuscitation to discharge in the sub-group with VT/VF was 21%, and only 4% for patients in asystole, which is in line with other studies. However, the rate of initiation of resuscitation by bystanders is low in Israel. These data may help the medical staff and the health policy providers in Israel. |
1,117 | Do positive health expectations and optimism relate to quality-of-life outcomes for the patient with an implantable cardioverter defibrillator? | Clinical trials with the implantable cardioverter defibrillator (ICD) have demonstrated desirable outcomes in terms of mortality and morbidity among patients with potentially lethal arrhythmias. This study examined the "resilience factors" of positive health expectations and global optimism prospectively using the general quality-of-life (QOL) scores of newly implanted ICD patients.</AbstractText>The study enrolled 88 newly implanted ICD patients (mean age, 65.3 +/- 13.2 years; 83% male; 92% white) assessed 8 and 14 months after ICD implantation. A series of 2 x 2 factorial multivariate analyses of covariance were performed to examine the differences between baseline low versus high positive health expectations and baseline low versus high optimism in short- and long-term general QOL scores.</AbstractText>After control was used for ejection fraction (mean, 31%), the patients with baseline high positive health expectations reported better general health at a long-term follow-up assessment (P = .002). The patients with high optimism reported better mental health and social functioning at a short-term follow-up assessment (P =. 056), and this finding approached significance at a long-term follow-up assessment (P = .061).</AbstractText>Positive health expectations and optimism are differentially related to various components of QOL. Collectively, these two resilience factors may be targeted in future studies of interventions to improve QOL for ICD patients.</AbstractText> |
1,118 | Effects of late regain of sinus rhythm on pulmonary artery pressure and functional status in patients with mitral valve replacement surgery and atrial fibrillation. | The study aim was to evaluate the effects of regaining sinus rhythm (SR) on pulmonary artery pressure (PAP) and NYHA class in patients undergoing mitral valve replacement (MVR) surgery and in atrial fibrillation (AF).</AbstractText>Forty patients (mean age 50.7+/-8.2 years) with previous MVRS and chronic AF were included in the study; the mean postoperative interval was 54.7+/-31.8 months. Among these 40 patients, 22 (the study group) were treated with amiodarone (600 mg/day) and direct current (DC) cardioversion (CV), while 18 (control group) underwent normal treatment.</AbstractText>In the study group, two patients regained SR with amiodarone loading, while 20 proceeded with DC CV at 21 days after amiodarone loading. SR was regained in 20 patients. The amiodarone dosage was lowered to 200 mg/day in the sixth postoperative week. Patients were followed for a mean of 18.0+/-4.4 months (range: 12-22 months). In the study group, recurrence of AF occurred in only one patient, at four months after DC CV. SR was maintained in 19 patients. At a clinical control examination, the mean NYHA class of study patients was decreased from 2.6+/-0.5 to 1.8+/-0.6 in two months, and to 1.5+/-0.6 in 12 months (p <0.01). Doppler echocardiographic follow up in the study group showed PAP to be significantly reduced, from 44.2+/-12.3 mmHg to 32.8+/-8.1 mmHg (p <0.01).</AbstractText>In patients with MVR and AF, amiodarone treatment and DC CV achieved good early and mid-term success in regaining and maintaining SR. Regulation of rhythm was concomitant with a reduction in PAP and improved NYHA functional class. Hence, a special effort should be made to correct arrhythmia in patients with MVR and AF.</AbstractText> |
1,119 | Determinants of health-related quality of life after aortic valve replacement in six-month survivors of intervention. | Although several determinants of survival after aortic valve replacement (AVR) have been identified, current knowledge regarding factors influencing the postoperative quality of life (QoL) is poor. The study aim was to evaluate health-related QoL (using Medical Outcome Study Short Form-36) in six-month survivors after AVR, and to determine predictors of outcome.</AbstractText>All patients undergoing heart valve surgery at the authors' hospital between 1992 and May 1999 were included. Data from 201 patients (119 males, 82 females; mean age 66.6 years) after AVR were obtained. The mean observation period was 42.5 months.</AbstractText>Patients in preoperative NYHA classes I and II had a postoperative QoL comparable to that of the general population, while subjects in NYHA classes III and IV scored significantly lower. Multivariate analysis identified four independent predictors (preoperative NYHA class, diabetes mellitus, prosthetic valve type, sternal complications) for the Physical component score. NYHA class, atrial fibrillation, sternal complications and type of valvular heart disease were predictors for the Mental component score. No correlation was found between preoperative left ventricular function or size, pre-existing coronary artery disease or prior myocardial infarction and the postoperative QoL.</AbstractText>Notably, preoperative aortic stenosis was identified as a strong and independent predictor of the postoperative QoL in six-month survivors after AVR. This effect was independent of left ventricular size and function. These findings support the proposal that patients with aortic stenosis should be operated on at an earlier stage, if possible before they develop symptoms.</AbstractText> |
1,120 | Minimally invasive close-chest method for creating reperfused or occlusive myocardial infarction in swine. | We sought to evaluate a closed-chest model for reperfused and occlusive myocardial infarction (MI) in pigs and to report experiences and pitfalls.</AbstractText>In 44 pigs, a balloon catheter was advanced into the left descending coronary artery (LAD) under fluoroscopic guidance. The balloon was inflated and occlusion of the vessel angiographically confirmed while ECG was continuously monitored. In case of ventricular fibrillation, direct current defibrillation was performed. In 6 animals, the balloon was left inflated during the following experiments, to obtain occlusive MI. In all other cases, the balloon was deflated after 45 minutes. After the experiments were finished, the hearts were stained with 2,3,5-triphenyltetrazolium chloride for assessment of infarct size.</AbstractText>MI was successfully induced in 34 animals (28 reperfused and 6 occlusive). Mean size of MI was 15.8 +/- 5.1% of left ventricular surface area for reperfused and 21.5 +/- 8.7% for occlusive infarcts. In one pig, 2,3,5-triphenyltetrazolium chloride did not confirm infarction. In 26 pigs, ventricular fibrillation occurred. Defibrillation was successful in 17 pigs. Failure rate because of ventricular fibrillation decreased from 42% (6) in the first 14 to 10% (3) in the next 30 animals. One animal died due to technical failure of the ventilator. After initial experiences, we used balloon catheters with a diameter of 2-3 mm, instead of 4 mm. The smaller balloon sizes were used so as to decrease the incidence of fibrillation.</AbstractText>The described technique of LAD occlusion presents a less invasive alternative to open chest models. The major pitfall, causing fatal arrhythmia in our series, was over-dilatation of the LAD with the balloon catheter.</AbstractText> |
1,121 | Role of the renin-angiotensin-aldosterone system in atrial fibrillation and cardiac remodeling. | This review summarizes recent clinical trial evidence showing a reduction in the development and recurrence of atrial fibrillation with angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor-blocking agents (ARBs). It then explores the possible mechanisms for this effect based on current animal models and limited human study.</AbstractText>Post hoc analyses of trials in patients with heart failure, hypertension, or myocardial infarction have observed reductions in atrial fibrillation among patients treated with ACE inhibitors or ARBs. Recent studies of these agents in animal models of atrial fibrillation suggest that they may prevent atrial fibrillation by reversing the cardiac structural and electrical changes, known as cardiac remodeling, that lead to the development of atrial fibrillation. This concept is also supported by two prospective studies showing that ACE inhibitors and ARBs prevent the recurrence of atrial fibrillation after electrical cardioversion.</AbstractText>Inhibition of the renin-angiotensin-aldosterone system is a novel concept for the treatment of atrial fibrillation that may target the underlying substrate of atrial fibrillation. Further human research is required to determine whether ACE inhibitors and ARBs prevent atrial fibrillation, and if so, whether this is a result of blood pressure lowering alone or a specific effect of these agents. Ongoing research will establish whether ACE inhibitors or ARBs have specific benefits in patients with atrial fibrillation.</AbstractText> |
1,122 | Update on advanced life support and resuscitation techniques. | This article is a review of the most recent findings in resuscitation techniques in advanced cardiac life support. The article focuses particularly on the period after July 1, 2003, but relevant new findings before this period are also included.</AbstractText>Randomized clinical trial results suggest that the current cardiopulmonary resuscitation and advanced cardiac life support guidelines may need to be modified. Early defibrillation during the electrical phase of cardiac arrest remains the most crucial intervention, but performing cardiopulmonary resuscitation before defibrillation may be more effective, as compared with immediate defibrillation, during the circulatory phase of cardiac arrest. Biphasic waveforms are superior to monophasic damped sine waveforms in achieving defibrillation. Novel cardiopulmonary resuscitation methods that increase negative intrathoracic pressure promote an increase in blood flow return to the heart. These devices have been correlated with improved short-term survival rates during the circulatory phase of cardiac arrest. Vasopressin administration, given alone or in combination with epinephrine, should be considered during the circulatory phase of out-of-hospital cardiac arrest, particularly in patients presenting with asystole as the initial rhythm. Induction of hypothermia during the metabolic phase in cardiac arrest survivors improves 6-month survival rates and neurologic outcomes.</AbstractText>Strategies to improve the low survival outcomes of cardiac arrest victims are available. Clinical trials testing these strategies suggest benefit from certain interventions but are not definitive. These different therapeutic interventions should be performed in a phase-specific-oriented fashion according to the three-phase time-sensitive model of cardiac arrest.</AbstractText> |
1,123 | A prospective, randomized trial to determine the early and late reactions after the use of iopamidol 340 (Niopam) and iobitridol 350 (Xenetix) in cardiac catheterization. | Intravascular contrast agents presently used in modern digital catheter laboratories during cardiac catheterization are superior to older agents as regards patient tolerance. There are, however, significant differences between these agents.</AbstractText>The aim of this study was to determine the incidence of early (< 24 hours) and late (> 24 hours to 7 days) reactions to 2 contrast agents currently used during cardiac catheterization: iopamidol 340 (Niopam) and iobitridol 350 (Xenetix).</AbstractText>This was a prospective, randomized, double-blinded trial. Two thousand and nineteen patients undergoing cardiac catheterization received one of the following contrast agents: iopamidol 340 (Niopam) and iobitridol 350 (Xenetix). Reactions that were possibly related to the contrast agents were recorded during hospital admission (early reaction) and after discharge (late reaction) by means of a questionnaire.</AbstractText>The baseline characteristics were matched in both the groups. There was no significant difference in the incidence of heat sensation experienced between the 2 groups, (p = 0.1). Early non-heat reactions occurred in 3.2% of patients receiving iopamidol 340 (Niopam) and 3.6% of those receiving iobitridol 350 (Xenetix), (p = 0.65). Electrocardiographic changes were recorded in 0.7% of patients who received iopamidol 340 (Niopam), and 2.6% of those who received iobitridol 350 (Xenetix), (p = < 0.01). Seven patients (0.8%) receiving iobitridol 350 suffered ventricular fibrillation requiring DC cardioversion compared with none in the iopamidol 340 group (p = < 0.01). Late reactions (post discharge symptoms) occurred in 13.9% of those receiving iopamidol 340 (Niopam) and 18.5% of those receiving iobitridol 350 (Xenetix) (p = 0.02).</AbstractText>Iobitridol 350 (Xenetix) was associated with more ECG changes and, importantly, ventricular fibrillation, than iopamidol (Niopam). There were no features to suggest other benefits from iobitridol 350. These results suggest that iopamidol 340 is a preferable contrast agent in cardiac catheterization.</AbstractText> |
1,124 | Genome-wide linkage scan identifies a novel genetic locus on chromosome 5p13 for neonatal atrial fibrillation associated with sudden death and variable cardiomyopathy. | Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and patients with AF have a significantly increased risk for ischemic stroke. Approximately 15% of all strokes are caused by AF. The molecular basis and underlying mechanisms and pathophysiology of AF remain largely unknown.</AbstractText>We have identified a large AF family with an autosomal recessive inheritance pattern. The AF in the family manifests with early onset at the fetal stage and is associated with neonatal sudden death and, in some cases, ventricular tachyarrhythmias and waxing and waning cardiomyopathy. Genome-wide linkage analysis was performed for 36 family members and generated a 2-point logarithm of the odds (LOD) score of 3.05 for marker D5S455. The maximum multipoint LOD score of 4.10 was obtained for 4 markers: D5S426, D5S493, D5S455, and D5S1998. Heterozygous carriers have significant prolongation of P-wave duration on ECGs compared with noncarriers (107 versus 85 ms on average; P=0.000012), but no differences between these 2 groups were detected for the PR interval, QRS complex, ST-segment duration, T-wave duration, QTc, and R-R interval (P>0.05).</AbstractText>Our findings demonstrate that AF can be inherited as an autosomal recessive trait and define a novel genetic locus for AF on chromosome 5p13 (arAF1). A genetic link between AF and prolonged P-wave duration was identified. This study provides a framework for the ultimate cloning of the arAF1 gene, which will increase the understanding of the fundamental molecular mechanisms of atrial fibrillation.</AbstractText> |
1,125 | Indications for and long-term survival in patients with automatic implantable cardioverter-defibrillators. | Automatic implantable cardioverter-defibrillators (AICDs) were implanted in 378 men and 95 women, mean age 69 +/- 12 years. At 3.6-year follow up, survival was 76% in patients who had an AICD because of cardiac arrest as a result of ventricular fibrillation or ventricular tachycardia not resulting from a transient or reversible cause; 85% in patients who had an AICD because of spontaneous sustained ventricular tachycardia in association with structural heart disease; 92% in patients who had an AICD because of syncope of undetermined origin with clinically relevant, hemodynamically sustained ventricular tachycardia or ventricular fibrillation induced at electrophysiological study when drug therapy is ineffective, not tolerated, or not preferred; 84% in patients who had an AICD because of nonsustained ventricular tachycardia with coronary artery disease, prior myocardial infarction, left ventricular dysfunction, and inducible ventricular fibrillation or sustained ventricular tachycardia at electrophysiological study that is not suppressible by a class I antiarrhythmic drug; and 85% in all 473 patients who had an AICD. |
1,126 | Stability of the ECG features of complete right bundle branch block over time: a methodological study for implementation in research and clinical practice. | Since research is concentrated to a large extent on patients with left bundle branch block, we aimed at evaluating the hypothesis that measurements of certain intervals and other characteristics of the ECG may change over time in patients with right bundle branch block (RBBB), and to design a model, which could be implemented in research and clinical practice, irrespective of the specific ECG features present. The duration of the QRS complex, QT, QTc, and PR intervals, the frontal QRS axis, the heart rate and the presence of hemiblocks, atrioventricular blocks, and atrial fibrillation were compared in the 1st and last of all available ECGs for each patient. Also, a subgroup of patients who had a ventricular aneurysm (VA) was compared with the remaining patients, with respect to the above variables. This longitudinal analysis included all of the patients with RBBB followed in our Cardiology Clinic. There were no significant changes in the ECG variables from the two ECGs recorded 487.6 +/- 410.1 (range 0-1,476) days apart, in the two comparisons carried out in 151 patients with RBBB. Comparison of the above-described ECG intervals and characteristics of patients with RBBB were found to be stable over the time course of the investigation. This methodological study is presented as a model to be used serially and prospectively in research and clinical practice for the follow-up of patients with bundle branch block, VA, dilated cardiomyopathy, congestive heart failure, or those considered for cardiac resynchronization therapy. |
1,127 | Preventing stroke in people with atrial fibrillation: a cross-sectional study. | The annual stroke rate in atrial fibrillation is around 5 per cent with increased risk in those with hypertension, diabetes, left ventricular dysfunction and other cardiovascular risk factors. This study set out to identify the patients with atrial fibrillation and modifiable risk factors for stroke.</AbstractText>Analysis of practice computer data taken from eight general practices (81 811 patients) in the south of England. 944 patients with a diagnosis of atrial fibrillation, of whom 782 (82.8 percent) were aged 65 years and over.</AbstractText>The age standardised prevalence of diagnosed atrial fibrillation was 1.23 per cent (1.28 percent for men and 1.18 percent for women). It was much more prevalent in the older population, 8.28 percent and 6.66 percent for males and females over 65, respectively. Cardiovascular co-morbidities were more frequent with increasing age. Blood pressure (BP) was recorded in over 95 per cent of patients with atrial fibrillation though there was scope for improving control; 25 per cent of men and 31 per cent women had a BP over 150/90. Inconsistent recording of ECG and echocardiography made it hard to identify patients with left ventricular dysfunction. Forty six percent of men and 37 percent of women were either being prescribed Warfarin, or had contraindications to its use; of those on Warfarin 75.9 percent have an international normalized ratio in range. Forty four per cent were treated with aspirin. People at high risk of stroke were no more likely to be treated with Warfarin or aspirin than those at moderate risk.</AbstractText>The rate of use of Warfarin remains low, and there is scope for better recording and management of risk factors particularly BP.</AbstractText> |
1,128 | Perioperative approach to a patient with Brugada syndrome. | Brugada syndrome is a recently described cardiac anomaly that may be responsible for up to one half of all sudden cardiac deaths in young adults without structural heart disease. It may also be worsened by beta-blockers, and it is almost unreported in the English language anesthesia literature. |
1,129 | Surgery for arrhythmias in children. | Transcatheter radiofrequency ablation to treat supraventricular and ventricular arrhythmias has supplanted routine surgical ablative therapy and redefined its role. A small population of arrhythmia patients now requires surgical ablation: those who have failed catheter ablation, patients with concomitant congenital heart disease in association with arrhythmias, those with atrial fibrillation and very young patients for whom transcatheter techniques are prohibitive because of small size, cyanosis or distorted anatomy.</AbstractText>From July 1992 through August 2003, 133 patients underwent arrhythmia surgery at Children's Memorial Hospital, 50% (67/133) in association with Fontan conversion (FC), 22% (28/133) with concomitant initial Fontan (IF) procedure and 28% (38/133) for various arrhythmias (MISC) in patients with (36/38, 95%) or without (2/38, 5%) associated structural heart disease. Mean age at surgery in the FC group was 20+/-7.6 years (median 19 years), and in the IF group and the MISC group, mean ages were 8.1+/-8.9 (median 4.2) years and 16.4+/-10.9 (median 11.3) years, respectively.</AbstractText>There were three operative (3/133, 2.6%; 1 FC, 2 MISC) and three late deaths (2 FC, 1 MISC). Four patients in the FC group had progressive ventricular failure and underwent successful cardiac transplantation. Follow-up data are available for non-transplant, surviving patients and reveal 11 incidences of persistent arrhythmia recurrence and 2 new-onset arrhythmias. Five of the 11 recurrences occurred early in our series of FC patients, when isthmus block interruption of arrhythmia foci was performed. Four additional recurrences occurred later in the FC series, two post-maze and two post-Cox-maze III. In the MISC group, there were two recurrences. Atrial reentry tachycardia (ART) recurred in a patient with no structural heart disease and accessory connection-mediated tachycardia recurred in a child who underwent concomitant initial Fontan. Two patients had ventricular tachycardia inducible at postoperative studies (2/7, 29%), but no clinical recurrence. Two new-onset tachycardias occurred, one child developed ART post-surgical ablation of accessory connections and one patient with inducible ventricular tachycardia developed ART 5 years postoperatively.</AbstractText>Variations in atrial and ventricular anatomy that may limit the catheter approach can be addressed surgically. Patient size or anatomic complexity should not be limiting factors in the combined surgical arrhythmia approach. Incorporation of arrhythmia therapy into planned surgical revision should be considered.</AbstractText> |
1,130 | Comparison of response to cardiac resynchronization therapy in patients with sinus rhythm versus chronic atrial fibrillation. | Cardiac resynchronization therapy (CRT) is a new therapeutic option for patients who have drug-refractory end-stage heart failure. Much information has been obtained from patients who have sinus rhythm, but the use of CRT in patients who have chronic atrial fibrillation (AF) has not been studied extensively. Accordingly, we evaluated the clinical response and long-term survival rate of CRT in patients who had heart failure and chronic AF, and the results were compared with those in patients who had sinus rhythm and who underwent CRT. Sixty patients who had end-stage heart failure (30 had sinus rhythm and 30 had chronic AF), New York Heart Association classes III to IV, left ventricular ejection fraction <35%, QRS interval >120 ms, and a left bundle branch block received a biventricular pacemaker. New York Heart Association class, Minnesota Quality of Life score, and 6-minute walking distance were evaluated at baseline and after 6 months of CRT. Long-term follow-up was </=2 years. New York Heart Association class, Minnesota Quality of Life score, and 6-minute walking distance improved significantly in the 2 groups after 6 months of CRT. The number of nonresponders was greater among patients who had AF. Nevertheless, the long-term survival rate was comparable between patients who had sinus rhythm and those who had AF. Patients who had AF demonstrated comparable benefit from CRT as those who had sinus rhythm. |
1,131 | Frequency of arrhythmic events during head-up tilt testing in patients with suspected neurocardiogenic syncope or presyncope. | Head-up tilt testing (HUT) is a useful diagnostic tool for evaluating suspected neurocardiogenic syncope. Although arrhythmic events during HUT have been occasionally reported, their incidence in a large number of patients is unknown. We aimed to assess the incidence and clinical significance of arrhythmic events in patients with suspected neurocardiogenic syncope who underwent HUT with isoproterenol provocation. For 2,242 patients who underwent HUT, the incidence of total arrhythmic events was 31%: bradyarrhythmias 24%, premature beats 4%, and tachyarrhythmias 3%. For 547 patients who developed bradyarrhythmias during HUT, the incidence of junctional arrhythmias was 92%. For 702 arrhythmic events, the incidence of arrhythmic events during the first phase of HUT was significantly lower than the second phase (p <0.001). The incidence of arrhythmic events in patients with positive HUT responses was significantly higher than in those with negative responses (p <0.001). In patients with positive responses, bradyarrhythmias were noted in 85%, and junctional arrhythmia was the most common arrhythmic event. Of the positive responses, 353 patients (61%) had the vasodepressive type, 181 (32%) patients the mixed type, and the remaining 39 (7%) the cardioinhibitory type. Of 2,242 patients, ventricular fibrillation occurred in 1 patient (0.04%). Thus, bradyarrhythmias were the most common arrhythmic events during HUT with isoproterenol provocation. Serious ventricular tachyarrhythmia rarely occurred. |
1,132 | Effects of Y-27632, a selective Rho-kinase inhibitor, on myocardial preconditioning in anesthetized rats. | The objective of this study was to examine the effects of Y-27632, a selective Rho-kinase inhibitor, on ischemic preconditioning (IP) and carbachol preconditioning (CP) in anesthetized rats. Administration of Y-27632 (0.1 mg/kg) produced slight, but not significant, reduction in mean arterial blood pressure and suppressed the total number of ventricular ectopic beats (VEBs). IP, induced by 5 min coronary artery occlusion and 5 min reperfusion, decreased the incidence of ventricular tachycardia (VT) from 100 (n=30) to 25% (n=24) and abolished the occurrence of ventricular fibrillation (VF) (40% in control group) during 30 min of ischemia. The incidences of VT and VF in Y-27632+IP group were found to be similar to IP group. Carbachol (4 microg/kg/min for 5 min) induced marked depressions in mean arterial blood pressure, heart rate and attenuated the total number of VEBs, but significant reductions in VT and VF incidences were noted in Y-27632+CP group. Y-27632 infusion for 5 min abolished VF occurrence. Marked reductions in plasma lactate levels were observed in all treatment and preconditioning groups. IP led to marked decrease in malondialdehyde levels. Decreases in infarct size were also observed with all groups when compared to control. These results suggest that infusion of Y-27632 was able to produce cardioprotective effects on myocardium against arrhythmias, infarct size or biochemical parameters and mimic the effects of ischemic preconditioning in anesthetized rats. Therefore, it is likely that inhibition of Rho-kinase is involved in the signaling cascade of myocardial preconditioning. |
1,133 | Nonlinear modeling of the atrioventricular node physiology in atrial fibrillation. | A nonlinear model of the atrioventricular (AV) node physiology in atrial fibrillation (AF) is proposed based on three assumptions: (1) normal distribution of atrial impulses, (2) right-skewed distribution of R-R intervals, (3) increase in the refractory period of the AV node due to rapid bombardment from the atria. Simulation resulted in the following conclusions, all of which are in agreement with previous experience: (1) the entry speed of atrial impulses into the AV node in AF is inversely proportional to the ventricular rate, (2) the autocorrelation function of R-R intervals is zero at all delays, (3) a newly introduced index, sign of first difference, has a negative autocorrelation function at the first delay and zero ones at all others. In spite of its simplicity, the model is able to explain what happens in atrial premature complexes, sinus tachycardia and sinus bradycardia. Different rhythms, some of which rarely seen clinically, can be reproduced by changing input patterns or by slightly manipulating the model parameters. In order to make possible a long irregular time series of R-R interval, aperiodic changes in atrial signals are shown to be necessary. In conclusion, we proposed a simple model for the AV node physiology capable of explaining the previously known facts about AF as well as predicting interesting properties of some other supraventricular arrhythmias. |
1,134 | Myocardial infarct size-limiting effect of chronic hypoxia persists for five weeks of normoxic recovery. | We examined cardioprotective effect of chronic hypoxia and the time course of its recovery under normoxic conditions. Adult male Wistar rats were exposed to intermittent hypobaric hypoxia (7000 m, 8 h/day, 35 exposures) and susceptibility of their hearts to ischemia-induced ventricular arrhythmias and myocardial infarction was evaluated in anesthetized open-chest animals subjected to 30-min coronary artery occlusion and 4-h reperfusion on the day after the last hypoxic exposure and at 7, 35 and 90 days of normoxic recovery. The infarct size was reduced from 69.2+/-1.7 % of the area at risk in normoxic controls to 48.0+/-2.2 % in the chronically hypoxic group and to 61.6+/-2.3 % in the group recovered for 7 days. This residual protection persisted for at least 35 days of normoxic recovery but it was absent after 90 days. In contrast to the infarct size-limitation, the antiarrhythmic protection disappeared already during the first week; the incidence of ventricular fibrillation was even significantly increased 7 and 90 days after the last hypoxic exposure. In conclusion, the duration of cardioprotection induced by chronic hypoxia differs markedly, depending on the end point of ischemia/reperfusion injury examined. Whereas the increased tolerance to lethal myocardial injury persists for at least 5 weeks after the termination of hypoxia, the antiarrhythmic protection rapidly vanishes, being replaced with transient proarrhythmic effect. |
1,135 | Atrial fibrillation in a multiethnic inpatient population of a large public hospital. | Atrial fibrillation (AF) has not been well-studied in minority and underserved populations. We report a one-year inpatient experience of AF among 80,021 total ECG records in a multiethnic population of a large public hospital.</AbstractText>ECG parameters, demographic data, discharge diagnoses, and discharge status were compiled for the first 1,999 hospitalizations associated with AF among 80,021 total ECG records and compared among the population subgroups.</AbstractText>Of 3,935 records of patients with AF, 737 matched first hospitalizations. Mean age was 62.3 years; 56% were male. Hispanics comprised 59.2%, Caucasians 16.4%, Asians 11.1%, African Americans 10.3%; unclassified 3%; 30.6% were uninsured. Compared to Caucasians, Left ventricular hypertrophy was more common in African-American [9.9% vs. 21.1%, odds ratio (OR)=2.3] and Asians (9.9% vs. 15.3%, OR=2.76). At discharge, Caucasians more frequently had coronary artery disease, compared to Hispanics (26.4% vs. 17.7%, OR=0.62), African Americans (26.4% vs. 10.5%, OR=0.36), and Asians (26.4% vs. 8.5%, OR=0.25); cardiomyopathy was less common in Caucasians as compared to African Americans (2.5% vs. 10.5%, OR=4.2), Hispanics (2.5% vs. 3.9%, OR=1.5) and Asians (2.5% vs. 4.9%, OR=1.96). Mortality was 16%; nonsurvivors compared to survivors were older, 64.9 years vs. 61.8 years, p<0.05, more frequently had myocardial infarction (20.4% vs. 6.2%, p=0.000) and stroke (16.5% vs. 5.0%, p=0.000).</AbstractText>This AF population, particularly African Americans, was younger than previously reported. ECG and discharge parameters had differential frequencies among race/ethnic subgroups. Nonsurvivors were older and more commonly had myocardial infarction and stroke. Further study is warranted of AF occurrence, management, and outcomes in lower-socioeconomic, multiethnic populations.</AbstractText> |
1,136 | Complications of reperfusion in acute aortic artery occlusion following saddle embolization originating from an atrial myxoma. | A 58-year-old man presented to the hospital with an 8-hour history of acute-onset bilateral lower limb ischemia. A large saddle embolus had occluded the aorta and could not be removed by balloon endarterectomy through the femoral arteries. Successful open aortic and femoral thromboembolectomy followed by extensive fasciotomies was accompanied by severe reperfusion injury. Life-threatening hyperkalemia was associated with three episodes of intraoperative ventricular fibrillation and ventricular tachycardia requiring cardiac massage and defibrillation. A dextrose-insulin-bicarbonate infusion was required to correct the hyperkalemia. Rhabdomyolysis developed at 24 hours, causing marked myoglobinuria and acute renal failure, which required hemofiltration. Histology of the recovered embolus confirmed an atrial myxoma, and when the patient had fully recovered, open cardiac surgery was carried out to resect the tiny stump of residual myxoma. Rhabdomyolysis associated with a myxomatous saddle embolus has not been previously reported. This case highlights the need for pre- and perioperative measures to be taken to overcome hyperkalemia and acute renal failure when revascularizing acute, massive, prolonged ischemia of the lower body. |
1,137 | Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator. | The implanted cardioverter defibrillator (ICD) improves survival in high-risk cardiac patients. This analysis from the MADIT-II trial database examines the long-term clinical course and subsequent mortality risk of patients after termination of life-threatening ventricular tachyarrhythmias by an ICD.</AbstractText>Life-table survival analysis was performed, and proportional hazards regression analysis was used to evaluate the contribution of baseline clinical factors and time-dependent defibrillator therapy to mortality during long-term follow-up. Of 720 patients with an ICD (average follow-up 21 months), 169 patients received 701 antiarrhythmic device therapies for ventricular tachyarrhythmias. Few baseline characteristics distinguished patients who received appropriate ICD therapy for their first ventricular tachyarrhythmic episode. The probability of survival for at least 1 year after first therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) was 80%. The hazard ratios for the risk of death due to any cause in those who survived appropriate therapy for termination of VT and VF were 3.4 (P<0.001) and 3.3 (P=0.01), respectively, compared with those who survived without receiving ICD therapy, with a high frequency of heart failure and late nonsudden cardiac death after first successful ICD therapy for VF.</AbstractText>Successful appropriate therapy by an ICD for VT or VF is associated with 80% survival at 1 year after arrhythmia termination. These patients are at increased risk for heart failure and nonsudden cardiac death after device termination of VT or VF and should receive special attention for the prevention and management of progressive left ventricular dysfunction during long-term follow-up.</AbstractText> |
1,138 | Stroke reduction in hypertensive adults with cardiac hypertrophy randomized to losartan versus atenolol: the Losartan Intervention For Endpoint reduction in hypertension study. | The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study showed that treatment with the angiotensin II type-1 receptor antagonist losartan reduces overall stroke risk compared with conventional therapy with the beta-blocker atenolol. We conducted secondary analyses in LIFE to determine the extent to which the cerebrovascular benefits of losartan apply to different clinical subgroups and stroke subtypes and to assess the dependence of these benefits on baseline and time-varying covariates. Among 9193 hypertensive patients with electrocardiographic evidence of left ventricular hypertrophy, random allocation to losartan-based treatment lowered the risk of fatal (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.43 to 0.96; P=0.032) and atherothrombotic stroke (HR, 0.72; 95% CI, 0.59 to 0.88; P=0.001) compared with atenolol-based therapy. Although comparable risk reductions occurred for hemorrhagic and embolic stroke, these were not statistically significant. The number of neurological deficits per stroke was similar, but there were fewer strokes in the losartan group for nearly every level of stroke severity. Effects were consistent in all clinical subgroups except for those defined by age and ethnicity. The benefits of losartan on all strokes were independent of baseline and time-varying risk factors, including blood pressure. The number needed to treat for 5 years to prevent 1 stroke was 54 for the average participant, declining to 25, 24, and 9 for patients with cerebrovascular disease, isolated systolic hypertension, and atrial fibrillation, respectively. In conclusion, substantial cerebrovascular benefit could be realized with the institution of losartan-based therapy over conventional therapy among hypertensive patients with left ventricular hypertrophy across the spectrum of cardiovascular risk. |
1,139 | Teaching public access defibrillation to lay volunteers--a professional health care provider is not a more effective instructor than a trained lay person. | Survival improves in witnessed out-of-hospital cardiac arrest if the victim receives bystander-initiated cardiopulmonary resuscitation and rapid defibrillation (BLS/AED). The European Resuscitation Council has a simple programme to teach these life-saving skills that require no previous experience of automated external defibrillators (AEDs). To be able to implement the use of AEDs widely, many instructors are needed, and therefore, lay persons may also be used as trainers. The purpose of this randomized study was to compare lay volunteers trained by a lay person with those trained by a health care professional using the Objective Structured Clinical Examination (OSCE).</AbstractText>Eight instructors, including four lay persons and four health care professionals, were given a basic course and an instructor course in CPR-D by the same instructor. All newly trained instructors trained 38 lay volunteers (19 pairs) who had no previous training in the use of a defibrillator. The lay volunteers performed the OSCE 2-3 weeks after the course. The OSCE comprised two scenarios with a manikin: the first, a patient in cardiac arrest with ventricular fibrillation, and the second, an imminent cardiac arrest with asystole as the initial rhythm. The same OSCE was performed by a group of lay first aiders practicing every 2 weeks who served as the control group.</AbstractText>No statistical difference was present between the two groups of lay volunteers in the OSCE. All were able to use the AED and follow instructions. They identified patients with ventricular fibrillation and cardiac arrest, but had difficulties identifying cases with imminent cardiac arrest. The control group of trained first aiders performed significantly more effectively than the newly trained lay persons.</AbstractText>No significant benefit exists in the trainer being a health care professional, but thorough training and subsequent rehearsing of the skills learned are crucial.</AbstractText> |
1,140 | Outcome of out-of-hospital cardiac arrest--why do physicians withhold resuscitation attempts? | To describe the outcome of out-of-hospital cardiac arrest (OHCA) with a focus on why physicians withhold resuscitation attempts.</AbstractText>Prospective collection of data during 12 months by the anaesthesiologists from the Advanced Life Support unit (ALS) of the Emergency Medical Service (EMS) according to the Utstein template.</AbstractText>In total, 499 OHCA were analysed and 266 patients received cardiopulmonary resuscitation (CPR) by the ALS unit. Initial rhythm was ventricular fibrillation (VF)/pulseless ventricular tachycardia (VT) in 35%, asystole in 38%, and other rhythm in 27%. Of the 266 treated patients, 83 (31%) patients had a spontaneous circulation on admission to hospital. Survival to discharge from hospital was 6.2% for all cases of OHCA, 11.7% for all 266 treated patients, and 20.5% for patients with witnessed cardiac arrest and presumed cardiac aetiology in VF. On arrival, the physician decided in 233 cases to withhold or discontinue CPR. The explanation for this was prolonged anoxia (74%), terminal cancer (8%), and severe trauma (7%). The most common incident locations were the patient's home and nursing homes. These locations were more common in the group where resuscitation was not attempted and these patients were older and the proportions of females and asystole were significantly higher. Bystander CPR was provided in 82 (16%) overall, but only in 8 (3%) in the group where resuscitation was not attempted.</AbstractText>Survival to discharge from hospital in all cases of OHCA was 6.2% but 20.5% in witnessed, presumed cardiac aetiology in VF. The decision to withhold resuscitation was based upon presumed prolonged anoxia in the majority of cases.</AbstractText> |
1,141 | Vasopressin administered with epinephrine is associated with a return of a pulse in out-of-hospital cardiac arrest. | Recent data suggest that using vasopressin in combination with epinephrine (adrenaline) may improve treatment of out-of-hospital cardiac arrest. This study examined local experience with the combination of epinephrine and vasopressin administration.</AbstractText>Data were obtained from an urban, municipal emergency medical service that does not include vasopressin in its formulary. A physician is dispatched to the scene of all cardiac arrest patients treated by this system. Vasopressin could be administered in addition to epinephrine to subjects with out-of-hospital cardiac arrest by the on-scene physician. Demographic information, drug administration and return of pulses were abstracted from patient care records for a 1-year interval. Multivariate logistic regression was used to assess the relationship between vasopressin use and outcomes.</AbstractText>During the study period, data were available for 298 subjects receiving epinephrine-only (n=231, 78%), a combination of 40 IU vasopressin and epinephrine (n=37, 12%) or no vasopressor drugs (n=30, 10%). Among patients receiving vasopressor drugs, pulse was restored for 74 subjects (28%), and 56 subjects (21%) had a pulse on arrival at the hospital. Return of pulses was associated with witnessed collapse, bystander CPR, and an initial ECG rhythm of ventricular fibrillation or tachycardia. Subjects receiving vasopressin and epinephrine were more likely to have a return of pulses during the resuscitation (LR: 2.73; 95% CI: 1.24, 6.03) and at hospital arrival (3.85; 1.71, 8.65) than subjects treated with epinephrine alone.</AbstractText>There is an association between using vasopressin in combination with epinephrine and restoration of circulation after out-of-hospital cardiac arrest.</AbstractText> |
1,142 | Improved prediction of defibrillation success for out-of-hospital VF cardiac arrest using wavelet transform methods. | We report an improved method for the estimation of shock outcome prediction based on novel wavelet transform-based time-frequency methods. Wavelet-based peak frequency, energy, mean frequency, spectral flatness and a new entropy measure were studied to predict shock outcome. Of these, the entropy measure provided optimal results with 60 +/- 6% specificity at 91 +/- 2% sensitivity achieved for the prediction of return of spontaneous circulation (ROSC). These results represent a major improvement in shock prediction in human ventricular fibrillation. |
1,143 | Cardiopulmonary resuscitation with a novel chest compression device in a porcine model of cardiac arrest: improved hemodynamics and mechanisms. | The goal of this study was to determine the magnitude and mechanisms of hemodynamic improvement of an automated, load-distributing band device (AutoPulse, Revivant Corp., Sunnyvale, California) compared with conventional cardiopulmonary resuscitation (C-CPR).</AbstractText>Improved blood flow during cardiopulmonary resuscitation (CPR) enhances survival from cardiac arrest.</AbstractText>AutoPulse CPR (A-CPR) and C-CPR were performed on 30 pigs (16 +/- 4 kg) 1 min after induction of ventricular fibrillation. Aortic and right atrial pressures were measured with micromanometers. Regional flows were measured with microspheres; A-CPR and C-CPR were performed with 20% anterior-posterior chest compression, with (n = 10) and without (n = 10) epinephrine. A pressure transducer was advanced down the airways during chest compressions (n = 10), and magnetic resonance imaging (MRI) was performed.</AbstractText>AutoPulse CPR improved coronary perfusion pressure (CPP) (aortic - right atrial pressure) without epinephrine (A-CPR 21 +/- 8 mm Hg vs. C-CPR 14 +/- 6 mm Hg, mean +/- SD, p < 0.0001) and with epinephrine (A-CPR 45 +/- 11 mm Hg vs. C-CPR 17 +/- 6 mm Hg, p < 0.0001). AutoPulse CPR improved myocardial flow without epinephrine and cerebral and myocardial flow with epinephrine (p < 0.05). AutoPulse CPR also produced greater myocardial flow at every CPP (p < 0.01). With A-CPR, high airway pressure was noted distal to the carina, which corresponded to an area of airway collapse on MRI, and which was not present with C-CPR.</AbstractText>AutoPulse CPR improved hemodynamics over C-CPR in this pig model. AutoPulse CPR with epinephrine can produce pre-arrest levels of myocardial and cerebral flow. The improved hemodynamics with A-CPR appear to be mediated through airway collapse, which likely impedes airflow and helps maintain higher levels of intrathoracic pressure.</AbstractText> |
1,144 | Use of intravenous flecainide in horses with naturally-occurring atrial fibrillation. | It has been reported that i.v. flecainide has a high efficacy for the treatment of experimentally-induced acute atrial fibrillation (AF) in horses and that its use is associated with minimal toxic side effects.</AbstractText>The objectives were to study the efficacy of i.v. flecainide as a treatment for atrial fibrillation in horses with naturally-occurring AF.</AbstractText>Ten horses with naturally-occurring AF were treated with 2 mg/kg bwt flecainide i.v. at a rate of 0.2 mg/kg bwt/min. In 3 horses, the infusion was continued at 0.05-0.10 mg/kg bwt/min until a total dose of 3.0 mg/kg bwt had been administered. Heart rate, QRS duration and average interval between fibrillation waves were measured before, during and following flecainide infusion. If conversion to normal sinus rhythm was not achieved, horses were treated with quinidine sulphate per os at a dose of 22 mg/kg bwt given every 2 h.</AbstractText>None of the horses with chronic AF (n = 9) converted to sinus rhythm with flecainide i.v. The only horse treated successfully had acute AF of 12 days' duration. The QRS duration and fibrillation cycle length increased significantly (P = 0.006 and 0.002, respectively) during and following flecainide infusion. Heart rate did not increase significantly over time however, 3 horses developed heart rates in excess of 100 beats/min. Two horses developed a potentially dangerous ventricular dysrhythmia during the first 15 mins of treatment. Quinidine sulphate given per os restored sinus rhythm in 8 out of 9 horses, with minimal adverse effects.</AbstractText>Although flecainide might be efficacious in cases of acute AF, it was not possible to restore sinus rhythm in horses with naturally-occurring chronic AF at the dosages used in this study. In 2 horses, 2.0 mg/kg bwt flecainide was associated with potentially dangerous dysrhythmias.</AbstractText>Intravenous administration of 2 mg/kg bwt flecainide is unlikely to convert chronic AF in horses and could induce dangerous dysrhythmias.</AbstractText> |
1,145 | Sudden suffocation by surgical sponge retained after a 23-year-old thoracic surgery. | A 70-year-old male patient with a 23-year-old history of right lower lung lobectomy for primary pulmonary adenocarcinoma (T1 N0 M0) presented with recurrent bronchopneumonia and purulent sputum. Pleural callus, lung abscess, bronchopleural fistula, and stitch granulomas were confirmed by chest x-ray, computed tomography scan, and bronchoscopy in the background of his complaints. An attempt to remove the bronchial purulent discharge and tissue sampling was made by using a flexible bronchoscope. The area of the lower trachea suddenly became clogged during bronchoscopic removal of the suspected piece of tissue (which later turned out to be organizing surgical gauze). The resuscitation following ventricular fibrillation failed to save the patient's life. The forensic postmortem examination confirmed the position of the foreign body extending from the abscess cavity, crossing the midline at carina and obstructing the lower trachea. This foreign body was a remnant of the surgical gauze left behind during a thoracic surgery 23 years ago. |
1,146 | Late onset of Wolff-Parkinson-White syndrome in a 72-year-old man. | We encountered a case of wide QRS tachycardia with chronic atrial fibrillation in Wolff-Parkinson-White syndrome. Unique features were late onset of syncope attacks associated with this tachycardia at an advanced age of 72 years old without previous documentation of Wolff-Parkinson-White syndrome on electrocardiogram. He had a high likelihood of sudden cardiac death. Catheter ablation using CARTO system easily led to a successful ablation of the accessory pathway. The mechanism of late onset of the wide QRS tachycardia was attributed to possible changes of electrophysiologic properties including the atrio-ventricular node and/or the accessory pathway, and the unique location of the accessory pathway. |
1,147 | Outpatient treatment of recent-onset atrial fibrillation with the "pill-in-the-pocket" approach. | In-hospital administration of flecainide and propafenone in a single oral loading dose has been shown to be effective and superior to placebo in terminating atrial fibrillation. We evaluated the feasibility and the safety of self-administered oral loading of flecainide and propafenone in terminating atrial fibrillation of recent onset outside the hospital.</AbstractText>We administered either flecainide or propafenone orally to restore sinus rhythm in 268 patients with mild heart disease or none who came to the emergency room with atrial fibrillation of recent onset that was hemodynamically well tolerated. Of these patients, 58 (22 percent) were excluded from the study because of treatment failure or side effects. Out-of-hospital self-administration of flecainide or propafenone--the "pill-in-the-pocket" approach--after the onset of heart palpitations was evaluated in the remaining 210 patients (mean age [+/-SD], 59+/-11 years).</AbstractText>During a mean follow-up of 15+/-5 months, 165 patients (79 percent) had a total of 618 episodes of arrhythmia; of those episodes, 569 (92 percent) were treated 36+/-93 minutes after the onset of symptoms. Treatment was successful in 534 episodes (94 percent); the time to resolution of symptoms was 113+/-84 minutes. Among the 165 patients with recurrences, the drug was effective during all the arrhythmic episodes in 139 patients (84 percent). Adverse effects were reported during one or more arrhythmic episodes by 12 patients (7 percent), including atrial flutter at a rapid ventricular rate in 1 patient and noncardiac side effects in 11 patients. The numbers of monthly visits to the emergency room and hospitalizations were significantly lower during follow-up than during the year before the target episode (P<0.001 for both comparisons).</AbstractText>In a selected, risk-stratified population of patients with recurrent atrial fibrillation, pill-in-the-pocket treatment is feasible and safe, with a high rate of compliance by patients, a low rate of adverse events, and a marked reduction in emergency room visits and hospital admissions.</AbstractText>Copyright 2004 Massachusetts Medical Society.</CopyrightInformation> |
1,148 | Catheter ablation for atrial fibrillation in congestive heart failure. | Congestive heart failure and atrial fibrillation often coexist, and each adversely affects the other with respect to management and prognosis. We prospectively evaluated the effect of catheter ablation for atrial fibrillation on left ventricular function in patients with heart failure.</AbstractText>We studied 58 consecutive patients with congestive heart failure and a left ventricular ejection fraction of less than 45 percent who were undergoing catheter ablation for atrial fibrillation. We selected as controls 58 patients without congestive heart failure who were undergoing ablation for atrial fibrillation, matched according to age, sex, and classification of atrial fibrillation. We evaluated the patients' left ventricular function and dimensions, symptom score, exercise capacity, and quality of life at baseline and at months 1, 3, 6, and 12.</AbstractText>After a mean (+/-SD) of 12+/-7 months, 78 percent of the patients with congestive heart failure and 84 percent of the controls remained in sinus rhythm (P=0.34) (69 percent and 71 percent, respectively, were in sinus rhythm without the administration of antiarrhythmic drugs). The patients with congestive heart failure had significant improvement in left ventricular function (increases in the ejection fraction and fractional shortening of 21+/-13 percent and 11+/-7 percent, respectively; P<0.001 for both comparisons), left ventricular dimensions (decreases in the diastolic and systolic diameters of 6+/-6 mm and 8+/-7 mm, respectively; P=0.03 and P<0.001, respectively), exercise capacity, symptoms, and quality of life. The ejection fraction improved significantly not only in patients without concurrent structural heart disease (24+/-10 percent, P<0.001) and those with inadequate rate control before ablation (23+/-10 percent, P<0.001), but also in those with coexisting heart disease (16+/-14 percent, P<0.001) and adequate rate control before ablation (17+/-15 percent, P<0.001).</AbstractText>Restoration and maintenance of sinus rhythm by catheter ablation without the use of drugs in patients with congestive heart failure and atrial fibrillation significantly improve cardiac function, symptoms, exercise capacity, and quality of life.</AbstractText>Copyright 2004 Massachusetts Medical Society.</CopyrightInformation> |
1,149 | Manifestation of Brugada syndrome after pacemaker implantation in a patient with sick sinus syndrome. | A 49-year-old woman experienced syncope 10 months after DDD pacemaker implantation for sick sinus syndrome. ECG revealed abnormal ST elevation in leads V1 to V3 during a paced rhythm. Multifocal premature ventricular contractions followed by ventricular fibrillation were documented. Saddleback-type ST elevation was confirmed after a mode change to AAI. The diagnosis of Brugada syndrome was made, and the DDD pacemaker was upgraded to an implantable cardioverter defibrillator. Brugada syndrome can be easily overlooked if the classic ECG findings are not initially noted but may be observed even during pacing therapy. |
1,150 | Fever as a precipitant of idiopathic ventricular fibrillation in patients with normal hearts. | Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract.</AbstractText>We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22, 9, and 18 months in the three patients, no ventricular arrhythmias have been recorded.</AbstractText>We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope.</AbstractText> |
1,151 | Prevalence, predictors, and mortality significance of the causative arrhythmia in patients with electrical storm. | Electrical storm (ES) is characterized by either refractory ventricular tachycardia (VT) or ventricular fibrillation (VF). However, little is known about the prevalence, predictors, and mortality implications of the causative arrhythmia in ES. We sought to assess the prevalence, predictors, and survival significance of VT and VF as the causative arrhythmia of ES in implantable cardioverter defibrillator (ICD) patients.</AbstractText>Consecutive patients from January 2000 to December 2002 who presented to the ICD clinic with > or = 2 separate ventricular arrhythmic episodes requiring shock within 24 hours were included in the study. ICD interrogation confirmed the number of shocks and provided electrograms for interpretation of the causative arrhythmia. Patients were grouped as VF or VT according to the causative arrhythmia. Their prevalence, predictors, and mortality rates were compared. Of 2,028 patients assessed in the ICD clinic, 208 (10%) presented with ES. VF was the cause of ES in 99 of 208 patients, for an overall prevalence of 48%. Original ICD indication, coronary artery disease, and amiodarone therapy were predictive for the causative arrhythmia. There was no mortality difference between the VT and VF groups; however, both groups had significantly increased mortality compared to a control ICD population without ES.</AbstractText>VF is the causative arrhythmia for a sizable proportion of patients with ES. The initial ICD indication, coronary artery disease, and amiodarone therapy are predictors of the causative arrhythmias in ES. There does not appear to be any mortality difference between ES patients with VT and VF, but mortality is increased in patients with ES versus control ICD patients without ES.</AbstractText> |
1,152 | Case reports. 1. An autopsy case of fatal arrhythmia induced by injuries of the atrioventricular conduction system: a case report. | A 65-year-old woman died three days after being involved in a traffic accident, following an episode of ventricular fibrillation. She was diagnosed as having suffered cardiac contusion, liver contusion, mediastinal hematoma and rib fracture on admission. Her electrocardiogram showed complete right bundle branch block, complete atrioventricular block, and right axis deviation. Aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and creatine kinase-MB were found to be elevated on biochemical blood analysis. These findings recovered and her condition appeared to improve daily. At autopsy, epicardial and intramyocardial haemorrhage were macroscopically seen in the posterior wall of the bilateral ventricles. On microscopic examination, there was evidence of fresh haemorrhage and coagulative necrosis with inflammatory reaction in the ordinary myocardium and adipose tissue around the atrioventricular node, which had spread to the proximal portion of the His' bundle. It is considered that these findings caused ventricular fibrillation to occur, and that the cause of death in this case was myocardial contusion due to blunt thoracic injury. This case would indicate that myocardium nearby atrioventricular junction is vulnerable to external force. Moreover, it would seem that fatal arrhythmia occasionally occurs during the follow-up stage, despite the lack of any significant clinical findings. |
1,153 | Supraventricular tachyarrhythmias in Ebstein anomaly: management and outcome. | This study was undertaken to review the role of electrophysiology testing and to determine the early and late results of medical and surgical management of supraventricular tachyarrhythmias in Ebstein anomaly.</AbstractText>We reviewed 130 patients between 1990 and 2001 with Ebstein anomaly and history of tachyarrhythmia with a median age of 25 years (mean age 27.5 years); 106 underwent electrophysiologic testing and 24 had documented atrial flutter or fibrillation. We excluded 21 patients: negative results of testing (n = 18), ventricular tachycardia (n = 2), and junctional tachycardia (n = 1). The remaining 109 patients had more than one mechanism: accessory pathway-mediated tachycardia (n = 49), atrioventricular nodal reentrant tachycardia (n = 10), and atrial flutter/fibrillation (n = 70).</AbstractText>Eighty-three patients underwent at least one arrhythmia procedure combined with surgery for Ebstein anomaly. Early mortality was 4.8%. Forty-one patients underwent surgical ablation of an accessory pathway without recurrent accessory pathway-mediated tachycardia at a mean follow-up of 48 months. Seven patients underwent surgical perinodal cryoablation for atrioventricular nodal reentrant tachycardia without recurrence at a mean follow-up of 57 months. Forty-eight patients underwent surgical intervention for atrial flutter or fibrillation (right-sided maze procedure, n = 38, and cryoablation of the atrial isthmus, n = 10). Freedom from recurrent atrial flutter or fibrillation was 75% at a mean follow-up of 34 months.</AbstractText>Concomitant arrhythmia procedures can be performed without increase in early mortality and should be added to Ebstein repairs for all patients who have supraventricular tachyarrhythmias. Surgical procedures for accessory pathway-mediated tachycardia and atrioventricular nodal reentrant tachycardia give excellent (100%) freedom from recurrence of those arrhythmias. Surgical intervention for atrial flutter/fibrillation yields freedom from late recurrence in 75% of cases.</AbstractText> |
1,154 | Oral arsenic trioxide poisoning and secondary hazard from gastric content. | In a suicide attempt, a 54-year-old man ingested arsenic trioxide. Gastric lavage was performed, but most of the poison remained as a mass in his stomach. A total gastrectomy was also performed to avoid intestinal perforation and arsenic poisoning. After the operation, he developed ventricular fibrillation. At one point, his circulation recovered spontaneously, but he later died from refractory circulatory failure. Many medical staff members were exposed to fumes from the patient's stomach. Some of the staff were diagnosed with corneal erosion or laryngitis. Because arsenic trioxide reacts with acid to produce arsine, the symptoms experienced by medical staff are directly attributable to arsine produced as a result of the reaction of arsenic trioxide with gastric acid. This case highlights the need for the introduction of protective measures to safeguard medical staff from exposure to arsine gas during the treatment of patients poisoned from ingested arsenic trioxide. |
1,155 | Predictors of gastrointestinal complications after conventional and beating heart coronary surgery. | Gastrointestinal complications after cardiac surgery remain a significant problem despite improvements in pre-operative, operative and post-operative care. The pathophysiology is uncertain, and their prevention remains suboptimal. This prospective, randomised study was designed to define the role of cardiopulmonary bypass (CPB) and cardioplegic arrest in the pathogenesis of gastrointestinal complications following coronary artery surgery.</AbstractText>Three hundred patients were prospectively randomised to (1) on-pump conventional coronary artery surgery [150 patients, 114 men, mean age 64 (45-75 years)] with mild hypothermic (32c) CPB and cardioplegic arrest of the heart or (2) off-pump surgery [150 patients, 113 men, mean age 64 (38-66) years] on the beating heart. The association of perioperative factors with gastrointestinal complications was investigated by univariate analysis. Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of gastrointestinal complications. There were no significant baseline differences between the groups. Eleven patients in the on-pump group and one patient in the off-pump group had post-operative gastrointestinal complications. Univariate analysis showed that CPB inclusive of cardioplegic arrest, left ventricular ejection fraction <50%, emergency surgery, prolonged aortic cross clamp and CPB time, post-operative low cardiac output syndrome, post-operative inotropic requirement, new onset atrial fibrillation (AF), excessive post-operative blood loss and redo thoracotomy <24 hours were predictors of gastrointestinal complications after coronary artery surgery (all p<0.05). However, stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only predictor of post-operative gastrointestinal complications (OR7.4; CI 3.4-17.9).</AbstractText>Cardiopulmonary bypass, inclusive of cardioplegic arrest, is the main independent predictor of post-operative gastrointestinal complications in patients undergoing coronary revascularisation.</AbstractText> |
1,156 | Dietary flaxseed protects against ventricular fibrillation induced by ischemia-reperfusion in normal and hypercholesterolemic Rabbits. | Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the (n-3) PUFA found in fish oils, exert antiarrhythmic effects during ischemia. Flaxseed is the richest plant source of another (n-3) PUFA, alpha-linolenic acid (ALA), yet its effects remain largely unknown. Our objective was to determine whether a flaxseed-rich diet is antiarrhythmic in normal and hypercholesterolemic rabbits. Male New Zealand White (NZW) rabbits (n = 14-16) were fed as follows: regular diet (REG group); diet containing 10% flaxseed (FLX group); 0.5% cholesterol (CHL group); or 0.5% cholesterol + 10% flaxseed (CHL/FLX group) for up to 16 wk. Plasma cholesterol was significantly elevated in the CHL and CHL/FLX groups. Plasma triglycerides were unchanged. ALA levels increased significantly in plasma and hearts of the FLX and CHL/FLX groups. After the feeding period, rabbit hearts were isolated and subjected to global ischemia (30 min) and reperfusion (45 min). Ventricular fibrillation (VF) occurred during ischemia in 33% of REG but in none of FLX hearts, and 28% of CHL but only 6% of CHL/FLX hearts. VF incidence during reperfusion was 28% and 26% in REG and FLX hearts, respectively. The incidence significantly increased to 64% in CHL hearts, and was significantly attenuated (18%) in CHL/FLX hearts. CHL markedly prolonged the QT interval, whereas FLX significantly shortened the QT interval and reduced arrhythmias in the FLX and CHL/FLX hearts. In vitro application of (n-3) PUFA shortened the action potential duration, an effect consistent with the QT data. This study demonstrates that dietary flaxseed exerts antiarrhythmic effects during ischemia-reperfusion in rabbit hearts, possibly through shortening of the action potential. |
1,157 | Amplified transmural dispersion of repolarization as the basis for arrhythmogenesis in a canine ventricular-wedge model of short-QT syndrome. | The short-QT syndrome is a new clinical entity characterized by corrected QT intervals <300 ms and a high incidence of ventricular tachycardia (VT) and fibrillation (VF). Gain-of-function mutations in the gene for outward potassium currents have been shown to underlie the congenital syndrome. The present study examined the cellular basis of VT/VF in an experimental model associated with short QT intervals created with a potassium channel activator.</AbstractText>Transmembrane action potentials from epicardial and M regions, 4 transmural unipolar electrograms, and a pseudo-ECG were simultaneously recorded in canine arterially perfused left ventricular wedge preparations. At a basic cycle length of 2000 ms, pinacidil (2 to 3 mumol/L) abbreviated the QT interval from 303.7+/-5.4 to 247.3+/-6.9 ms (mean+/-SEM, P<0.0001). The maximal transmural dispersion of repolarization (TDR(max)) increased from 27.0+/-3.8 to 64.9+/-9.2 ms (P<0.01), and an S2 applied to the endocardium induced a polymorphic VT (pVT) in 9 of 12 wedge preparations (P<0.01). Addition of isoproterenol (100 nmol/L, n=5) led to greater abbreviation of the QT interval, a further increase in TDR(max) (from 55.4+/-13.7 to 69.7+/-8.3 ms), and more enduring pVT. TDR(max) was correlated significantly with the T(peak)-T(end) interval under all conditions. The effects of pinacidil were completely reversed by glybenclamide (10 micromol/L, n=4) and partially reversed by E4031 (5 micromol/L, n=5), which prevented induction of pVT in 3 of 5 preparations.</AbstractText>Our data suggest that heterogeneous abbreviation of the action potential duration among different cell types spanning the ventricular wall creates the substrate for the genesis of VT under conditions associated with short QT intervals.</AbstractText> |
1,158 | Heart-directed expression of a human cardiac isoform of cAMP-response element modulator in transgenic mice. | The transcriptional activation mediated by cAMP-response element (CRE) and transcription factors of the CRE-binding protein (CREB)/CRE modulator (CREM) family represents an important mechanism of cAMP-dependent gene regulation possibly implicated in detrimental effects of chronic beta-adrenergic stimulation in end-stage heart failure. We studied the cardiac role of CREM in transgenic mice with heart-directed expression of CREM-IbDeltaC-X, a human cardiac CREM isoform. Transgenic mice displayed atrial enlargement with atrial and ventricular hypertrophy, developed atrial fibrillation, and died prematurely. In vivo hemodynamic assessment revealed increased contractility of transgenic left ventricles probably due to a selective up-regulation of SERCA2, the cardiac Ca(2+)-ATPase of the sarcoplasmic reticulum. In transgenic ventricles, reduced phosphorylation of phospholamban and of the CREB was associated with increased activity of serine-threonine protein phosphatase 1. The density of beta(1)-adrenoreceptor was increased, and messenger RNAs encoding transcription factor dHAND and small G-protein RhoB were decreased in transgenic hearts as compared with wild-type controls. Our results indicate that heart-directed expression of CREM-IbDeltaC-X leads to complex cardiac alterations, suggesting CREM as a central regulator of cardiac morphology, function, and gene expression. |
1,159 | Short-term complications and resource utilization in matched subjects after on-pump or off-pump primary isolated coronary artery bypass. | Studies suggest that patients who undergo off-pump coronary artery bypass grafting (OPCABG) have fewer short-term complications and use fewer inpatient resources than do patients who undergo standard coronary artery bypass grafting (CABG) with extracorporeal circulation. However, dissimilarity between groups in risk factors for complications has hindered interpretation of results.</AbstractText>To compare the prevalence of selected complications (atrial fibrillation, stroke, reoperation, and bleeding) and inpatient resource utilization (length of stay, discharge disposition, total charges) between subjects undergoing primary isolated CABG or OPCABG who were matched with respect to key risk factors.</AbstractText>Retrospective, causal-comparative survey conducted in 1 center for 18 months. Patients who underwent primary isolated CABG or OPCABG were matched for sex, age (within 2 years), left ventricular ejection fraction (within 0.05), and graft-patient ratio (exact match) and compared for prevalence of new-onset atrial fibrillation, stroke, reoperation within 24 hours, and bleeding. Statistical analysis included Wilcoxon and t tests for paired comparisons.</AbstractText>The sample (107 matched pairs) was 63% male, with a mean age of 66 (SD 9.5) years, a mean left ventricular ejection fraction of 0.51 (SD 0.13), and a mean graft-patient ratio of 3.41 (SD 0.74). The 2 groups did not differ significantly in New York Heart Association class (P = .43), Acute Physiology and Chronic Health Evaluation III score (P = .22), postoperative beta-blocker use (P = .73), or comorbid conditions. None of the complications examined differed significantly between pairs.</AbstractText>Patients with comparable risk profiles have similar prevalences of selected complications after CABG and OPCABG.</AbstractText> |
1,160 | Equivalence of the bioimpedance and thermodilution methods in measuring cardiac output in hospitalized patients with advanced, decompensated chronic heart failure. | An accurate and reliable noninvasive method for determining cardiac output/cardiac index would be valuable for patients with acutely decompensated advanced systolic heart failure.</AbstractText>To determine whether a correlation exists for cardiac output and index determined by using bioimpedance and thermodilution in patients with acutely decompensated complex heart failure and if differences between results with the 2 methods could be explained by the patients' advanced condition.</AbstractText>Cardiac output and index were determined by using bioimpedance and thermodilution in 33 patients. Echocardiographic and electrocardiographic data were assessed to determine if differences between results with the 2 methods could be explained by the patients' advanced condition. Concordance correlation coefficients and Bland-Altman agreement between methods were calculated.</AbstractText>Four patients were excluded from analysis because reliable measurements could not be obtained; the remaining 29 patients constituted the study population. Mean cardiac outputs determined by thermodilution and bioimpedance were 5.48 and 5.40 L/min, respectively (rhoc = 0.89, P < .001), and mean cardiac indexes were 2.67 and 2.65 (rhoc = 0.82, P < .001). Mean bias (limits of agreement) between data pairs was 0.08 (-0.18 to 0.35) L/min (P = .52) for cardiac output and 0.03 (-0.097 to 0.16; P = .61) for cardiac index. Six data pairs (21%) had an absolute percent difference greater than 15%. Of these, 50% had a higher thermodilution value.</AbstractText>Determinations of cardiac output and index by both methods were significantly correlated. Mean bias between the 2 methods was small, suggesting clinical utility for bioimpedance in patients with complex decompensated heart failure.</AbstractText> |
1,161 | Transvenous cardioverter-defibrillator implantation with a double coil lead via persistent left superior vena cava. | A dual-coil defibrillation lead was inserted in a 64-year-old male through a persistent left superior vena cava draining into the coronary sinus. The lead, connected to a cardioverter-defibrillator (ICD) implanted in the left pectoral area, was looped in the right atrium positioning the proximal and distal lead coils in the coronary sinus and right ventricular outflow track respectively and resulting in a low and stable defibrillation threshold. Because of its relative ease and effectiveness, this procedure may be recommended in patients with persistent left superior vena cava requiring an ICD implant. |
1,162 | Effect of desflurane-induced preconditioning following ischemia-reperfusion on nitric oxide release in rabbits. | Nitric oxide (NO) is the mediator of ischemic preconditioning against myocardial infarction. Desflurane produces anesthetic preconditioning to protect the myocardium against infarction. In the model of myocardial ischemia-reperfusion injury in rabbits, we evaluated desflurane-induced ischemic preconditioning and studied its mechanism of NO synthesis. Thirty-two male adult New Zealand white rabbits were anesthetized with intravenous (IV) 30 mg/kg pentobarbital followed by 5 mg/kg/hr infusion. All rabbits were subjected to 30 minutes (min) long lasting left anterior descending coronary artery (LAD) occlusion and three hours (hr) of subsequent reperfusion. Before LAD occlusion, the rabbits were randomly allocated into four groups for preconditioning treatment (eight for each group). The control group did not receive any preconditioning treatment. The desflurane group received inhaled desflurane 1.0 MAC (minimal end-tidal alveolar concentration) for 30 min that was followed by a 15 min washout period. The L-NAME-desflurane group received L-NAME (NG-nitro-L-arginine methyl ester; non-selective Nitric Oxide Synthetase (NOS) inhibitor) 1 mg/kg IV 15 min before 1.0 MAC inhaled desflurane for 30 min. The L-NAME group received L-NAME 1 mg/kg IV. Infarct volume, ventricular arrhythmia, plasma lactate dehydrogenase (LDH), creatine kinase (CK) activity and myocardial perfusion were recorded simultaneously. We have found that hemodynamic values of the coronary blood flow before, during, and after LAD occlusion were not significantly different among these four groups. For the myocardial ischemia-reperfusion injury animals, the infarction size (mean +/- SEM) in the desflurane group was significantly reduced to 18 +/- 3% in the area at risk as compared with 42 +/- 7% in the control group, 35 +/- 6 in the L-NAME group, and 34 +/- 4% in the L-NAME-desflurane group. The plasma LDH, CK levels, and duration of ventricular arrhythmia were also significantly decreased in the desflurane group during ischemia-reperfusion injury. Our results indicate that desflurane is an anesthetic preconditioning agent, which could protect the myocardium against the ischemia-reperfusion injury. This beneficial effect of desflurane on the ischemic preconditioning is probably through NO release since L-NAME abrogates the desflurane preconditioning effect. |
1,163 | Upper limit of vulnerability determination during implantable cardioverter-defibrillator placement to minimize ventricular fibrillation inductions. | The defibrillation threshold (DFT) and upper limit of vulnerability (ULV) were determined using step-down protocols in 50 patients who underwent implantable cardioverter-defibrillator placement or testing. The sensitivity and specificity of each ULV energy level was assessed for detecting an increased DFT, correlation of the DFT and ULV, and optimal shock timing for ULV determination. A ULV <10 or 11 J (failure to induce ventricular fibrillation with 10- to 11-J shocks) was 100% predictive of an acceptable DFT and may be sufficient to exclude unacceptable DFTs in 60% of implantable cardioverter-defibrillator recipients. All 4 shocks used to scan the peak of the T wave during ULV testing were necessary for accurate ULV determination. |
1,164 | Left ventricular outflow tract obstruction due to anomalous insertion of papillary muscle. | A 56-year-old man who complained of quadrantic hemianopsia was admitted to determine its etiology. Cerebral angiography revealed no organic stenosis. Echocardiography showed clear direct continuity between a hypertrophied anterolateral papillary muscle and the anterior mitral leaflet, and the left ventricular (LV) outflow tract (LVOT) was narrowed by the presence of an accessory papillary muscle. The LVOT obstruction caused an intra-LV pressure overload that resulted in LV concentric hypertrophy. Arrhythmia, such as paroxysmal atrial fibrillation (PAF), was thought to have caused a cerebral embolism. Mitral valve replacement (MVR), septal myectomy, and myectomy of the abnormal papillary muscle were performed, and complete release of the LVOT obstruction was accomplished. Anomalous insertion of papillary muscle is a rare cause of LVOT obstruction. Echocardiography was useful in identifying the papillary muscle malformation, and surgery was completely curative. |
1,165 | Is the ratio of transmitral peak E-wave velocity to color flow propagation velocity useful for evaluating the severity of heart failure in atrial fibrillation? | Although analysis of the transmitral inflow (TMF) pattern is widely used for evaluating left ventricular diastolic function and provides valuable information for the management of heart failure (HF) in sinus rhythm, its utility in patients with atrial fibrillation (AF) has not been established. The aim of this study was to investigate the relationship between the ratio of transmitral peak E-wave velocity to flow propagation velocity (E/Vp) obtained by a newly developed dual Doppler system and the plasma B-type natriuretic peptide (BNP) concentration or pulmonary capillary wedge pressure (PCWP) for evaluating the severity of heart failure with AF.</AbstractText>In 68 patients with AF, the E/Vp was compared with plasma BNP concentration and PCWP. A cutoff value of > or =1.7 for E/Vp predicted a plasma BNP concentrationl of > or =200 pg/ml, with 80% sensitivity and 84% specificity. Only E/Vp was found to be independently significant by stepwise multilinear regression analysis (r=0.40, p=0.01). PCWP values had good correlation with E/Vp (r=0.63, p<0.01) and were significantly higher in the group with E/Vp >/=1.7 (16+/-6 mmHg vs 11+/-4 mmHg, p<0.05).</AbstractText>The Doppler-derived index of E/Vp correlated well with the neurohormonal and hemodynamic parameters, and was useful for evaluating the severity of heart failure with AF.</AbstractText> |
1,166 | Psychological traits and emotion-triggering of ICD shock-terminated arrhythmias. | We have previously reported on the triggering of arrhythmia and hence, implanted cardioverter-defibrillators (ICD) shock by strong emotion. The purpose of the present study was to examine whether concordant psychological traits distinguish patients who experience emotion-triggered ICD shock.</AbstractText>Two hundred forty ICD patients completed the Speilberger Trait Anxiety and Anger Inventories and Anger Expression Scale, and the abridged Cook-Medley Hostility Scale approximately 2 months after ICD implantation. Patients were also given a structured diary to record mood states retrospectively for the period 0 to 15 minutes preceding ICD shock and for a period corresponding to the same time of day 1 week later. Patients who reported emotion-triggered ICD shock were compared on concordant psychological measures to patients who did not.</AbstractText>Patients who reported at least moderate anger in the 0 to 15 minutes before ICD shock scored significantly higher on Speilberger Trait Anger (24.18 +/- 3.97 vs. 17.04 +/- 2.17, p < .0001), and Cook-Medley Aggressive Responding (5.76 +/- 0.75 vs. 3.96 +/- 1.30, p < .0001) and Hostile Affect (3.59 +/- 0.80 vs. 2.04 +/- 1.02, p < .0001), and lower on Speilberger Anger Control (7.94 +/- 1.43 vs. 10.64 +/- 1.19, p < .001) than those who did not. In multivariate analysis, only Trait Anger remained a significant predictor of anger-triggered shock (chi2 = 7.10, p < .008). Patients who reported at least moderate anxiety in the 0 to 15 minutes before ICD shock scored significantly higher on Speilberger Anxiety (22.43 +/- 1.65 vs. 19.96 +/- 1.71, p < .0001) than those who did not.</AbstractText>Stable psychological factors are associated with risk for ICD-shock triggered by concordant strong emotion.</AbstractText> |
1,167 | Heart rate recovery after exercise: a predictor of ventricular fibrillation susceptibility after myocardial infarction. | Heart rate recovery after exercise, thought to be related to cardiac parasympathetic tone, has been shown to be a prognostic tool for all-cause mortality. However, the relationship between this variable and confirmed susceptibility to ventricular fibrillation (VF) has not been established. Therefore, myocardial ischemia was induced with a 2-min occlusion of the left circumflex artery during the last minute of exercise in mongrel dogs with myocardial infarction (n = 105 dogs). VF was induced in 66 animals (susceptible), whereas the remaining 39 dogs had no arrhythmias (resistant). On a previous day, ECG was recorded and a time-series analysis of heart rate variability was measured 30, 60, and 120 s after submaximal exercise (treadmill running). The heart rate recovery was significantly greater in resistant dogs than in susceptible dogs at all three times, with the most dramatic difference at the 30-s mark (change from maximum: 48.1 +/- 3.6 beats/min, resistant dogs; 31.0 +/- 2.2 beats/min, susceptible dogs). Correspondingly, indexes of parasympathetic tone increased to a significantly greater extent in resistant dogs at 30 and 60 s after exercise. These differences were eliminated by atropine pretreatment. When considered together, these data suggest that resistant animals exhibit a more rapid recovery of vagal activity after exercise than those susceptible to VF. As such, postexercise heart rate recovery may help identify patients with a high risk for VF following myocardial infarction. |
1,168 | Recent topics on the surgical treatment for atrial fibrillation. | After the introduction of endocardial radiofrequency catheter, only two arrhythmias, atrial fibrillation and ischemic ventricular tachycardia require surgical procedures. In this review, we describe recent advancements and problems of surgical treatment for atrial fibrillation. On the basis of multiple-circuit re-entry theory, Cox developed the maze operation with the aim of interrupting the re-entry circuit. Although this procedure has become the gold standard technique for the surgical treatment of atrial fibrillation with approximately 90% success rate, several modifications have been made over time. To obtain a more physiological atrial transport function, radial approach technique or bilateral appendage-preserved maze procedures were developed and to simplify surgical procedures, maze operation with cryo-ablation or radiofrequency-ablation were created. Other topics are concerned with surgical target or approach to atrial fibrillation. Ectopic focus theories from pulmonary veins have been widely recognized recently and the surgical isolation of pulmonary veins orifices is performed with various energy sources. In addition to standard cut-and-sew surgical technique, cryoablation, unipolar or bipolar radiofrequency ablation, or microwave ablation were induced with endocardial or epicardial approach for the achievement of less invasive cardiac surgery. As atrial fibrillation leads to frequent mortality, cardiac surgeons have to treat atrial fibrillation with other cardiac disease more frequently to obtain better quality of operative results. |
1,169 | Pharmacological cardioversion of atrial fibrillation: current management and treatment options. | Atrial fibrillation (AF) is the most common form of arrhythmia, carrying high social costs. It is usually first seen by general practitioners or in emergency departments. Despite the availability of consensus guidelines, considerable variations exist in treatment practice, especially outside specialised cardiological settings. Cardioversion to sinus rhythm aims to: (i) restore the atrial contribution to ventricular filling/output; (ii) regularise ventricular rate; and (iii) interrupt atrial remodelling. Cardioversion always requires careful assessment of potential proarrhythmic and thromboembolic risks, and this translates into the need to personalise treatment decisions. Among the many clinical variables that affect strategy selection, time from onset is crucial. In selected patients, pharmacological cardioversion of recent-onset AF can be a safely used, feasible and effective approach, even in internal medicine and emergency departments. In most cases of recent-onset AF, pharmacological cardioversion provides an important--and probably more cost effective--alternative to electrical cardioversion, which can then be employed as a second-line therapy for nonresponders. Class IC agents (flecainide or propafenone), which can be safely used in hospitalised patients with recent-onset AF without left ventricular dysfunction, can provide rapid conversion to sinus rhythm after either intravenous administration or oral loading. Although intravenous amiodarone requires longer conversion times, it is still the standard treatment for patients with heart failure. Ibutilide also provides good conversion rates and could be used for AF patients with left ventricular dysfunction (were it not for high costs). For long-lasting AF most pharmacological treatments have only limited efficacy and electrical cardioversion remains the gold standard in this setting. However, a widely used strategy involves pretreatment with amiodarone in the weeks before planned electrical cardioversion: this provides optimal prophylaxis and can sometimes even restore sinus rhythm. Dofetilide may also be capable of restoring sinus rhythm in up to 25-30% of patients and can be used in patients with heart failure. The potential risk of proarrhythmia increases the need for careful therapeutic decision making and management of pharmacological cardioversion. The results of recent trials (AFFIRM [Atrial Fibrillation Follow-up Investigation of Rhythm Management] and RACE [Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation]) on rate versus rhythm control strategies in the long term have led to a generalised shift in interest towards rate control. Although carefully designed studies are required to better define the role of pharmacological rhythm control in specific AF settings, this alternative option remains a recommendable strategy for many patients, especially those in acute care. |
1,170 | Clinical and pathological aspects of experimental oleander (Nerium oleander) toxicosis in sheep. | Dried Nerium oleander leaves at single lethal dose of 110 mg/kg body weight were administered orally to six native male sheep. Clinical signs of toxicosis in sheep began to appear about 30 min after receiving the oleander and included decrease of the heart rate followed by cardiac pauses and tachyarrhythmias; ruminal atony, mild to moderate tympany, abdominal pain, polyuria and polakiuria. Electrocardiography revealed bradycardia, atrio-ventricular blocks, depression of S-T segments, ventricular premature beats and tachycardia, and ventricular fibrillation. Five sheep died within 4-12 h and one survived. At necropsy there were varying degrees of haemorrhages in different organs and gastroenteritis. Histopathological examination of tissue sections revealed myocardial degeneration and necrosis, degeneration and focal necrosis of hepatocytes, necrosis of tubular epithelium in kidneys, oedema in the lungs, and ischemic changes in the cerebrum. |
1,171 | Obesity and the risk of new-onset atrial fibrillation. | Obesity is associated with atrial enlargement and ventricular diastolic dysfunction, both known predictors of atrial fibrillation (AF). However, it is unclear whether obesity is a risk factor for AF.</AbstractText>To examine the association between body mass index (BMI) and the risk of developing AF.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PARTICIPANTS" NlmCategory="METHODS">Prospective, community-based observational cohort in Framingham, Mass. We studied 5282 participants (mean age, 57 [SD, 13] years; 2898 women [55%]) without baseline AF (electrocardiographic AF or arterial flutter). Body mass index (calculated as weight in kilograms divided by square of height in meters) was evaluated as both a continuous and a categorical variable (normal defined as <25.0; overweight, 25.0 to <30.0; and obese, > or =30.0). In addition to adjusting for clinical confounders by multivariable techniques, we also examined models including echocardiographic left atrial diameter to examine whether the influence of obesity was mediated by changes in left atrial dimensions.</AbstractText>Association between BMI or BMI category and risk of developing new-onset AF.</AbstractText>During a mean follow-up of 13.7 years, 526 participants (234 women) developed AF. Age-adjusted incidence rates for AF increased across the 3 BMI categories in men (9.7, 10.7, and 14.3 per 1000 person-years) and women (5.1, 8.6, and 9.9 per 1000 person-years). In multivariable models adjusted for cardiovascular risk factors and interim myocardial infarction or heart failure, a 4% increase in AF risk per 1-unit increase in BMI was observed in men (95% confidence interval [CI], 1%-7%; P = .02) and in women (95% CI, 1%-7%; P = .009). Adjusted hazard ratios for AF associated with obesity were 1.52 (95% CI, 1.09-2.13; P = .02) and 1.46 (95% CI, 1.03-2.07; P = .03) for men and women, respectively, compared with individuals with normal BMI. After adjustment for echocardiographic left atrial diameter in addition to clinical risk factors, BMI was no longer associated with AF risk (adjusted hazard ratios per 1-unit increase in BMI, 1.00 [95% CI, 0.97-1.04], P = .84 in men; 0.99 [95% CI, 0.96-1.02], P = .56 in women).</AbstractText>Obesity is an important, potentially modifiable risk factor for AF. The excess risk of AF associated with obesity appears to be mediated by left atrial dilatation. These prospective data raise the possibility that interventions to promote normal weight may reduce the population burden of AF.</AbstractText> |
1,172 | Ventricular fibrillation median frequency may not be useful for monitoring during cardiac arrest treated with endothelin-1 or epinephrine. | In this study, we evaluated whether median fibrillation frequency (MF) and mean fibrillation amplitude (AMP) reflect coronary perfusion pressure (CoPP) and predict successful defibrillation. MF, AMP, and CoPP were measured during prolonged ventricular fibrillation (VF) cardiac arrest and resuscitation in pigs. After 5 min of VF, cardiopulmonary resuscitation was started. At 10 min, the pigs received randomly a single dose of endothelin-1 50 mug (n = 7), 100 mug (n = 7), or 200 mug (n = 5), or repeated doses of epinephrine 0.04 mg/kg (n = 6), or saline (n = 6) every 3 min. At 25 min, the pigs were defibrillated to achieve restoration of spontaneous circulation (ROSC). In a nonparametric spectral analysis of the individual MF versus CoPP and AMP versus CoPP curves, we found no link between the different curves in different animals or therapies. No difference was found in MF in pigs with ROSC (n = 8) compared with animals not achieving ROSC (n = 23) immediately before defibrillation (P = 0.85). Our data suggest that, in prolonged VF cardiac arrest, MF and AMP might not be useful tools to reflect myocardial perfusion. |
1,173 | Genetic disruption of Kir6.2, the pore-forming subunit of ATP-sensitive K+ channel, predisposes to catecholamine-induced ventricular dysrhythmia. | Metabolic-sensing ATP-sensitive K+ channels (KATP channels) adjust membrane excitability to match cellular energetic demand. In the heart, KATP channel activity has been linked to homeostatic shortening of the action potential under stress, yet the requirement of channel function in securing cardiac electrical stability is only partially understood. Here, upon catecholamine challenge, disruption of KATP channels, by genetic deletion of the pore-forming Kir6.2 subunit, produced defective cardiac action potential shortening, predisposing the myocardium to early afterdepolarizations. This deficit in repolarization reserve, demonstrated in Kir6.2-knockout hearts, translated into a high risk for induction of triggered activity and ventricular dysrhythmia. Thus, intact KATP channel function is mandatory for adequate repolarization under sympathetic stress providing electrical tolerance against triggered arrhythmia. |
1,174 | Prevalence of right ventricular dysplasia-cardiomyopathy in a non-referral hospital. | In a cardiological department of a non-referral hospital responsible for 80,000 inhabitants with 2500 in-hospital patients and 1500 out-hospital patients per year, the prevalence, symptoms and prognosis of arrhythmogenic right ventricular dysplasia-cardiomyopathy (ARVD/C) were examined retrospectively. From 1997 to 2002, ARVD/C was diagnosed in 35 females and 45 males (overall prevalence 1 in 1000 inhabitants) with a mean age of 45.6 years. Symptoms were chest pain (80%), palpitations (60%) and syncopes (30%), and clinical findings were repetitive ventricular premature beats (50%), supraventricular arrhythmias (30%), ventricular tachycardia (20%), aborted sudden death due to ventricular fibrillation (1%), right heart failure (4%), biventricular heart failure (1%) and high grade AV nodal block (4%). Endomyocardial biopsies were not performed. Aborted sudden death occurred in only one patient (0.3%) before the diagnosis was made, annual heart failure rate was 1%. No deaths appeared in a follow-up of 1-5 (mean 2.4) years with clinical assessment as the basis of diagnosis. The prevalence of ARVD/C is much higher and the prognosis better than expected from results of reference centers. |
1,175 | Utility of event loop recorders for the management of arrhythmias in young ambulatory patients. | We evaluated the diagnostic yield of event loop recorders in ambulatory patients referred for palpitations, dizziness or syncopal events and in whom a previous Holter recording was not diagnostic. A total of 96 patients were studied, 50 (52%) were men and 46 (48%) were women with a mean age of 37+/-10 years. Mean duration of the recording was 5.2+/-2.3 days. During the recording period, 24 of the 96 patients (25%) remained asymptomatic. Automatic recordings revealed significant arrhythmias in four (16.7%) patients, which included two (8.3%) cases of atrial fibrillation, one (4.2%) non-sustained ventricular tachycardia (VT) and one (4.2%) second degree atrio-ventricular (AV) block. The manual function of the recorder was used by 72 (75%) patients while they were symptomatic. Palpitations were the most common symptom, which corresponded most frequently to normal sinus rhythm (43.1%), followed by sinus tachycardia (16.7%). An arrhythmic substrate was found in 29 (40.3%) patients, including 13 (18.1%) with isolated ectopic beats of supraventricular and/or ventricular origin, 14 (19.4%) with supraventricular tachycardia (SVT) and 2 (2.8%) with second degree AV block. The data of our study showed that the ambulatory use of an event loop recorder in young patients during a mean period of 5 days was highly useful to elucidate the potential cause of their symptoms. The particular use of the manually triggered function during symptoms allowed to establish a clear correlation between symptoms and arrhythmic events including sinus tachycardia in 75% of patients. |
1,176 | [Myocardial ischemic postconditioning: a brief ischemia causes conversion of resistent reperfusion-induced ventricular fibrillation into the normal rhythm]. | Brief episodes of myocardial ischemia-reperfusion were shown to be protective against reperfusion injury when used during early reperfusion after a prolonged ischemic episode. This phenomenon has been termed myocardial ischemic postconditioning. In this study, an effect of ischemic postconditioning on persistent reperfusion-induced ventricular fibrillation was studied in the rat isolated heart. 2 minutes of global ischemia on the 15th minute of reperfusion after 30 minutes of regional ischemia effectively abolished the persistent ventricular fibrillation. In non-postconditioned hearts, the ventricular fibrillation continued to the end of reperfusion. The ischemic postconditioning seems to exert a strong antiarrhythmic effect protecting the heart against persistent reperfusion-induced ventricular tachyarrhythmias. |
1,177 | Reversible left ventricular dysfunction "takotsubo" cardiomyopathy associated with hyperthyroidism. | Myocardial stunning with hyperthyroidism is rare. A 79-year old woman with hyperthyroidism was admitted to our hospital complaining of palpitations due to paroxysmal atrial fibrillation. An echocardiogram showed akinesis of the apical wall which was not observed 2 weeks before admission. Cardiac catheterization performed in the acute phase showed normal coronary arteries and no evidence of provocative spasms. The wall motion abnormality disappeared entirely after 1 week in hospital. We report a case of transient left ventricular dysfunction, so called "takotsubo" cardiomyopathy, associated with hyperthyroidism. |
1,178 | Severe cardiac arrhythmias in young patients with myotonic dystrophy type 1. | Cardiac tachyarrhythmias have rarely been studied in young patients with myotonic dystrophy type 1 (DM1). The authors observed major cardiac rhythm disturbances in 11 patients aged 10 to 18 years. Tachyarrhythmic events were more frequent than impulse conduction disorders. Wide variations in CTG expansion were observed among the population. Since physical exercise was a prominent arrhythmogenic factor, systematic exercise tests with EKG monitoring may be indicated in young patients with DM1. |
1,179 | Short-term effects of right-left heart sequential cardiac resynchronization in patients with heart failure, chronic atrial fibrillation, and atrioventricular nodal block. | Single-site ventricular pacing in patients with heart failure, atrial fibrillation, and severe atrioventricular (AV) nodal block risks the generation of discoordinate contraction. Whether altering the site of stimulation can offset this detrimental effect and what role sequential right ventricular-left ventricular (RV-LV) stimulation might play in such patients remain unknown.</AbstractText>Nine subjects with heart failure (ejection fraction, 14% to 30%), atrial fibrillation, and AV block were studied by pressure-volume analysis. Ventricular stimulation was applied to the RV (apex and outflow tract), LV free wall, and biventricular (BiV) at 80 and 120 bpm. BiV improved systolic function more than either site alone (dP/dt(max), 810+/-83, 924+/-98, 983+/-102 mm Hg/s for RV, LV, BiV, respectively; P<0.05), although LV pacing was significantly better than RV pacing. However, only BiV improved diastolic function (isovolumic relaxation) over RV or LV alone. Similar results were obtained for both heart rates. RV pacing site did not alter the BiV effect, and concomitant stimulation of both RV sites did not improve function over each alone. Finally, varying RV-LV delay revealed optimal responses with simultaneous pacing.</AbstractText>Simultaneous BiV pacing acutely enhances both systolic and diastolic function over single-site RV or LV pacing in congestive heart failure patients with atrial fibrillation and advanced AV block. Sequential RV-LV stimulation offers minimal benefit on average and should perhaps be considered only in targeted subsets such as nonresponding patients.</AbstractText> |
1,180 | The ALPHA study (T-wave alternans in patients with heart failure): rationale, design and endpoints. | Sudden death and pump failure are the main causes of death in patients with heart failure. Patients with ischemic and non-ischemic cardiomyopathy are at similar risk of arrhythmic mortality; however, standard non-invasive and invasive tests are not routinely available for non-ischemic patients. T-wave alternans (TWA) has been proposed as a potential marker of susceptibility to ventricular tachycardia-fibrillation in several groups of patients.</AbstractText>The ALPHA study was designed to evaluate the independent predictive value of the measurement of microvolt TWA on the combined occurrence, after 18 months of follow-up, of cardiac death and life-threatening arrhythmias in a population of patients with non-ischemic dilated cardiomyopathy and NYHA class II and III. This is a multicenter prospective observational study. A total of 370 patients, with measurable TWA, will be enrolled during routine follow-up for heart failure treatment; a logbook will be used to collect basic information on the whole screened population. Patients will be enrolled during a 2-year period and will be followed up for 18 months. The primary endpoint of the study will be the combined incidence of cardiac death and life-threatening ventricular arrhythmias. The study will complete recruitment by mid 2004 and report in 2006.</AbstractText> |
1,181 | [Implantable cardioverter-defibrillator in the treatment of two patients with an increased risk of sudden cardiac death]. | A 23-year-old female with familial long-QT syndrome and a 48-year-old male with familial dilated cardiomyopathy were given an implantable cardioverter-defibrillator (ICD) as prophylaxis. About half a year after the implantation, there was an appropriate and successful ICD-discharge in both patients in connection with ventricular tachycardia. Treatment with an ICD can be life-saving in patients with cardiac rhythm disorders. The most common indication is ventricular tachycardia or fibrillation due to ischaemic heart disease, but an ICD may also be indicated in patients with cardiomyopathy, congenital heart disease, hereditary arrhythmia or a planned heart transplantation. |
1,182 | [The implantable cardioverter-defibrillator: sometimes necessary]. | The implantable cardioverter-defibrillator (ICD) is used in patients who are at risk for ventricular fibrillation after having suffered from a myocardial infarction. Initially, patient selection was limited to survivors of impending sudden death with coronary artery disease. Later, ICD implantation in high-risk coronary artery disease patients was found to lower cardiovascular mortality. More recently, patients with dilated cardiomyopathy and no coronary artery disease are also potential candidates for implantation of an ICD. In the Netherlands, it is expected that there will be 1-2 ICD-users per 10,000 inhabitants. This means that ambulance personnel, general practitioners and doctors in emergency wards will also be confronted with patients who have had one or more shock treatments. Such medical personnel should have knowledge about the function of the ICD, what to do if several shocks have been given and whom to contact in case problems persist. |
1,183 | Women and the implantable cardioverter defibrillator: a lifespan perspective on key psychosocial issues. | The clinical success of the implantable cardioverter defibrillator (ICD) in reducing mortality suggests that more women will be receiving ICDs in the future. The impact of ICD therapy in women is unique in western societies; the ICDs scar and lump in the pectoral area can lead to body image concerns due to the emphasis on women's physical attractiveness. Social support and roles are challenged because women's reaction to stress has been characterized by a "tend and befriend" response, involving cultivating and utilizing social networks, rather than the "fight or flight" response more typical of men. In addition, a woman's identity as a caretaker and caregiver can be threatened by the actual and perceived activity limitations imposed by the ICD or the underlying heart condition. Finally, reproductive and sexual health are important issues, as 25 to 50% of patients with ICDs report concerns in this area, but also report discomfort in discussing these concerns with their health care providers. The purpose of the present paper is to review the relevant literature and to identify the unique impact of the psychosocial issues of body image, social support and roles, and sexual development and reproductive functioning for women with ICDs across the lifespan. In the absence of complete empirical research data on the impact of these concerns, hypotheses to test in future research are offered. |
1,184 | [Beating heart coronary artery bypass grafting for acute myocardial infarction]. | We consider that off-pump coronary artery bypass grafting (CABG) [OPCAB], which results in local myocardial ischemia, is more effective for patients with acute myocardial infarction (AMI) than conventional CABG under cardiac arrest with global myocardial ischemia. Twenty-one patients (15 males, 6 females) received OPCAB for AMI, among whom surgery was performed following percutaneous coronary intervention (PCI) failure in 4 and PCI was performed prior to OPCAB in 2, while PCI was not performed in the remaining 15. Preoperatively, 16 patients had intraaortic balloon pumping (IABP), and 4 had IABP and percutaneous cardiopulmonary support (PCPS). The mean interval from onset to surgery was 11.7 (range 3 to 40) hours. In 20 cases, a complete revascularization was performed. The mean number of bypasses was 2.3 and OPCAB was carried out in 14 patients. In 2 cases, OPCAB was converted to on-pump beating CABG for complete revascularization. Fourteen patients (67%), each maintained with preoperative left ventricular ejection fraction (EF), were discharged with an elective bypass. Four patients died after on-pump beating CABG, in whom EF was lower than 10%. In addition, 3 died of low cardiac output syndrome (LOS) under PCPS and 1 of ventricular fibrillation. Based on our results, we considered that complete revascularization using OPCAB was effective for cases of AMI with PCI difficulty. However, in shock cases requiring PCPS, cardiac function was not improved even after revascularization. Therefore, it is necessary to study new procedures for shock cases during the period from onset to surgery. |
1,185 | Normal distribution of ventricular pressure-volume area of arrhythmic beats under atrial fibrillation in canine heart. | We previously found the frequency distribution of the left ventricular (LV) effective afterload elastance (E(a)) of arrhythmic beats to be nonnormal or non-Gaussian in contrast to the normal distribution of the LV end-systolic elastance (E(max)) in canine in situ LVs during electrically induced atrial fibrillation (AF). These two mechanical variables determine the total mechanical energy [systolic pressure-volume area (PVA)] generated by LV contraction when the LV end-diastolic volume is given on a per-beat basis. PVA and E(max) are the two key determinants of the LV O(2) consumption per beat. In the present study, we analyzed the frequency distribution of PVA during AF by its chi(2), significance level, skewness, and kurtosis and compared them with those of other major cardiodynamic variables including E(a) and E(max). We assumed the volume intercept (V(0)) of the end-systolic pressure-volume relation needed for E(max) determination to be stable during arrhythmia. We found that PVA distributed much more normally than E(a) and slightly more so than E(max) during AF. We compared the chi(2), significance level, skewness, and kurtosis of all the complex terms of the PVA formula. We found that the complexity of the PVA formula attenuated the effect of the considerably nonnormal distribution of E(a) on the distribution of PVA along the central limit theorem. We conclude that mean (SD) of PVA can reliably characterize the distribution of PVA of arrhythmic beats during AF, at least in canine hearts. |
1,186 | Conversion of atrial fibrillation to sinus rhythm during landiolol infusion. | A 71-year-old woman with a history of persistent atrial fibrillation underwent clipping of a ruptured cerebral artery aneurysm. During the surgery her cardiac rhythm was atrial fibrillation and the ventricular rate increased to 130 beats.min(-1). Administration of landiolol was started with 1-min loading infusion at 0.125 mg.kg(-1).min(-1) and continuous infusion at 0.04 mg.kg(-1).min(-1), which was effective in controlling the ventricular rate without causing hypotension. Approximately 120 min after the landiolol infusion was started, the atrial fibrillation was converted to sinus rhythm. Her sinus rhythm was maintained until she left the operating room, even after discontinuation of landiolol. |
1,187 | Radiofrequency ablation of ventricular fibrillation and multiple right and left atrial tachycardia in a patient with Brugada syndrome. | Brugada syndrome is a well-known form of idiopathic ventricular fibrillation (VF). Few data suggest that this arrhythmia may be triggered by ventricular premature beats (VPBs), and an association with other arrhythmia such as monomorphic ventricular tachycardia (VT) or supraventricular tachycardia (SVT) has been reported. In a highly symptomatic 18-year-old-male patient with this syndrome, frequent episodes of VF, fast polymorphic VT, and fast monomorphic sustained regular tachycardia were observed. The tachycardia episodes were classified as VT or VF and as a consequence received appropriate therapies with the implanted cardioverter defibrillator (ICD). Precipitating VPBs that were stored in the ICD memory and on the electrocardiogram (ECG) exhibited the same morphology as frequent isolated VPBs. During the electrophysiological study, right and left atrial tachycardia (AT) with one-to-one atrioventricular conduction were also induced and successfully ablated. VF was ablated using the same noncontact mapping (NCM) system triggering VPBs from right ventricular outflow tract (RVOT). |
1,188 | Outcome of right ventricular bifocal pacing in patients with permanent atrial fibrillation and severe dilated cardiomiopathy due to Chagas disease: three years of follow-up. | Several studies have shown that heart failure may benefit from cardiac resynchronization therapy (CRT). Studies have demonstrated a beneficial effect of right ventricular (RV) bifocal pacing, using two leads at different positions, in similar patient populations. The aim was to evaluate this approach in Chagas disease patients who developed both severe dilated cardiomiopathy and chronic atrial fibrillation.</AbstractText>The study included 30 patients with a mean age of 52 +/- 6 years (16 male), who had atrioventricular block at functional class II or IV (NYHA). Patients underwent endocardial dual-chamber pacemaker implantation with two RV leads-one placed near the RV outflow tract and the other in the apex. Patients were examined by echocardiography, 24-hour Holter, and New York Heart Association (NYHA) class determination before and 3, 6, 12, 18, 24, and 36 months after CRT.</AbstractText>Compared to the baseline, the left ventricular ejection fraction increased in the first month of CRT, the left ventricular end diastolic diameter decreased, all patients were downgraded to NYHA class I or II, and the incidence of ventricular arrhythmias decreased. However, these could not be maintained and worsened after 6 months CRT. There was a mortality rate of 43.3% during the first year, and only 23.3% of patients remained alive after 3 years. They underwent an electrophysiological study, which revealed complex arrhythmias justifying implantable cardioverter defibrillator (ICD) in six out of seven patients.</AbstractText>The favorable effects of RV bifocal pacing could not be maintained beyond the first 6 months, likely due to the ventricular arrhythmias. Therefore, CRT combined with ICD from the outset may be recommended for this patient group.</AbstractText> |
1,189 | Reverse remodelling of systolic left ventricular contraction pattern by long term cardiac resynchronisation therapy: colour Doppler shows resynchronisation. | To quantify long term effects of cardiac resynchronisation therapy (CRT) by biventricular pacing in patients with heart failure (HF).</AbstractText>Regional changes in left ventricular (LV) contraction patterns effected by CRT in 19 patients with HF (12 with ischaemia; mean (SD) age 66 (9) years) with bundle branch block were examined by colour Doppler tissue velocity imaging (c-TVI). Time differences during main systolic tissue velocity peak (SYS) were compared in the basal and mid LV interventricular septum and in the corresponding LV free wall segments.</AbstractText>From baseline to long term (9.8 (3.0) months) CRT, ejection fraction increased from 21.8 (5.4)% to 30.8 (7.6)%, LV end diastolic diameter decreased from 7.6 (0.9) cm to 7.1 (0.8) cm, and end systolic diameter decreased from 6.4 (1.2) cm to 6.0 (1.2) cm (p < 0.05). LV peak tissue velocities were unchanged during follow up. At baseline, SYS in LV free wall was typically delayed by an average of 29 ms in the basal LV site and by 18 ms in the mid LV site. The regional movements of the LV free wall and interventricular septum were separated by an average of only 14 ms and -4 ms (p < 0.05) at the basal site and by -21 ms and -16 ms at the mid LV site during short term and long term CRT, respectively.</AbstractText>The improved haemodynamic functions observed during CRT may be explained by a significant resynchronisation of the regional LV movement pattern during long term follow up.</AbstractText> |
1,190 | Postprandial variations in ST-segment in a patient with Brugada syndrome and partial gastrectomy. | A 74-year-old man with a history of partial gastrectomy presented with an electrocardiogram consistent with Brugada syndrome and marked meal related fluctuations in the ST segment. ST-segment elevation was prominently attenuated at 30 minutes and increased at 120 minutes after meals. Analysis of heart rate variability revealed a relationship between postprandial heightened parasympathetic activity and increase in Brugada-type ECG abnormality. A rapid postprandial increase in blood glucose may initially stimulate sympathetic nervous activity and secondarily increase parasympathetic tone. Food intake can be associated with fluctuations in ST-segment elevation in patients with the Brugada syndrome. |
1,191 | Direct comparison of a contractility and activity pacemaker sensor during treadmill exercise testing. | There are limited data about the chronotropic capacity of the peak endocardial acceleration (PEA) sensor. This study directly compared the chronotropic function from the PEA and the activity (ACT) sensor. The study included 18 patients (age 73 +/- 7 years) with > or = 75% pacemaker-driven heart rate (HR) and a PEA sensor and 11 healthy controls (age 67 +/- 7 years) underwent a chronotropic assessment exercise protocol (CAEP) exercise test with the pacemaker patients in VVIR mode after programming the sensors in the default setting with adjustment of the upper sensor rate as an age related maximum value (220-age). The ACT sensor was externally strapped on the thorax. Achieved exercise duration for the patients and controls was, respectively, 9.2 +/- 3 vs 18.4 +/- 4 minutes (P <0.001). The maximal achieved HR with the PEA sensor was 124 +/- 25 beats/min, versus the ACT with 140 +/- 23, versus the controls with 153 +/- 26 beats/min (P <0.001 between the groups). For the PEA, ACT, and controls, the time to peak HR was, respectively, 11 +/- 3, 7 +/- 3.6, and 18 +/- 4 (P <0.001 between groups) and HR after 10 minutes recovery was, respectively, 80 +/- 20, 65 +/- 15, and 82 +/- 4 beats/min (P <0.001 between groups). The PEA sensor functions hypochonotroop during exercise programmed as a single sensor system. It is, therefore, preferable to combine the PEA sensor with an activity-based sensor in a dual sensor system. Although both groups had normal left ventricular functions, the exercise capacity of pacemaker patients is significantly lower than in the controls. |
1,192 | Torsadogenic cardiotoxicity of antipsychotic drugs: a structural feature, potentially involved in the interaction with cardiac HERG potassium channels. | Many non-cardiovascular drugs of common clinical use cause, as an unwanted accessory property, the prolongation of the cardiac repolarisation process, due to the block of the HERG (Human Ether-a-go-go Related Gene) potassium channel, responsible for the repolarising I(Kr) current. This delayed cardiac repolarisation process can be often unmasked by a prolongation of the QT interval of the ECG. In these conditions, premature action potentials can generate morphologically anomalous after-polarisations, and trigger a dangerous kind of polymorphic ventricular tachyarrhythmia, known as torsade de pointes, which can evolve in ventricular fibrillation and death. The risk associated with the torsadogenic cardiotoxicity of drugs, which prolong the QT interval has been the topic of documents produced by many health authorities, giving important issues about the preclinical and clinical evaluation of cardiac safety. Besides, public and private research laboratories developed several experimental in vitro or in vivo strategies, aimed to an early recognition of the influence of a drug (or of a drug-candidate) on the HERG channel and/or on the cardiac repolarisation process. Also the identification of a possible pharmacophore model, common in all or at least in numerous torsadogenic drugs, could represent a first step for the development of useful in silico approaches, allowing a preliminary indication about the potential torsadogenic property of a given molecule. In this work, we described the electrophysiological basis of torsade de pointes and listed several pharmacological classes of torsadogenic drugs. Among them, we focused our attention on antipsychotics, with an accurate overview on the experimental and clinical reports about their torsadogenic properties. Moreover, a common structural feature exhibited by these drugs, despite of their remarkable chemical differences, is evidenced by a computational approach and is indicated as a possible "facilitating" requirement for their torsadogenic properties. Together with other remarks, coming from different computational studies, the individuation of a satisfactory "toxicophore" model could be greatly useful, for the theoretical prediction of torsadogenic properties of a given chemical moiety and for the design of new drugs devoid of such an undesired and potentially lethal side-effect. |
1,193 | Aetiology, comorbidity and drug therapy of chronic heart failure in the real world: the EPICA substudy. | Chronic heart failure (CHF) is common and is frequently managed by primary care physicians (PCPs). Despite the European Society of Cardiology (ESC) Guidelines, standard treatments for CHF are frequently underutilised, particularly in primary care.</AbstractText>To evaluate current drug therapy for CHF in adults with HF diagnosed according to ESC guidelines in the context of the EPICA study. Aetiological features and therapy relevant comorbidities were also analysed.</AbstractText>EPICA was a community-based epidemiological study conducted in mainland Portugal. The study involved 365 primary care physicians, who evaluated 6300 primary care attendees aged over 25 years. CHF was diagnosed by clinical and echocardiography criteria according to ESC guidelines.</AbstractText>Total of 551 cases of CHF were identified, with a mean age of 65+/-9 years. The estimated overall prevalence of CHF in the Portuguese population was 4.4%; 1.3% with and 1.7% without left ventricular systolic dysfunction (LVSD). There are 6,280,792 people aged >25 years in Portugal, which extrapolates to 261,400 cases of heart failure. About 80% of patients had a history of hypertension, 39% had a history of coronary artery disease and 15% had atrial fibrillation. Only 58% of patients were on angiotensin-converting enzyme (ACE) inhibitors and 7% on beta-blockers. The type of ventricular dysfunction, age and presence of renal failure had little effect on prescription rates. Diuretics were prescribed in 78%. Thiazides were used more frequently in those with preserved systolic function and frusemide in those with left ventricular systolic dysfunction. Digoxin was prescribed more often to patients with than without left ventricular systolic dysfunction (34% vs. 17%; p=0.02). Long-acting nitrates were prescribed to 20% and amiodarone to 8% of patients.</AbstractText>The EPICA study, as in other studies in primary care in Europe, particularly the IMPROVEMENT study, suggests that greater efforts are required to improve training of primary care teams in the management of CHF.</AbstractText> |
1,194 | Atrial fibrillation after surgical revascularization: is there any difference between on-pump and off-pump? | Postoperative atrial fibrillation (AF) is still frequent complication after cardiac surgery in spite of the improvements in the surgical procedures. There is still controversy whether or not, the absence of cardiopulmonary bypass results in a lower incidence of AF.</AbstractText>Six hundred and seventy patients that underwent revascularization by using in situ LIMA for single vessel disease were included in this retrospective study and the patients were divided in two groups. Group I included 328 patients who underwent complete revascularization with cardiopulmonary bypass and group II consisted of 342 patients who underwent complete revascularization without cardiopulmonary bypass. Then, the incidence and predictive perioperative factors of AF in two groups were determined and compared with each other.</AbstractText>There were no significant differences between two groups with respect to the preoperative demographic characteristics of the patients. The incidence of postoperative AF was determined as 16.1% after on-pump and 14.6% after off-pump revascularization. Avoiding cardiopulmonary bypass did not decrease the incidence of postoperative AF. Sex, age over 65 years, prophylactic beta-blocker usage and left ventricular dysfunction were independent predictive factors in group I (r2=0.51; P<0.001). However, only age over 65 years and prophylactic beta-blocker usage were independent predictive factors in group II (r2=0.59; P<0.01). The rates of AF in both groups were decreased by using prophylactic beta-blocker usage (P=0.05 in group I, P<0.001 in group II).</AbstractText>There is no reduction of AF rate in myocardial revascularization without cardiopulmonary bypass. However, prophylactic beta-blocker usage decreases the incidence of AF after both on-pump and off-pump myocardial revascularization.</AbstractText> |
1,195 | Effects of pre-, peri-, and postmyocardial infarction treatment with losartan in rats: effect of dose on survival, ventricular arrhythmias, function, and remodeling. | Angiotensin receptor blockers (ARBs) reduce adverse left ventricular (LV) remodeling and improve LV function and survival when started postmyocardial infarction (MI). ARBs also reduce ventricular arrhythmias during ischemia-reperfusion injury when started pre-MI. No information exists regarding their efficacy and safety when started pre-MI and continued peri- and post-MI. We evaluated whether the ARB losartan improves the outcome when started pre-MI and continued peri- and post-MI. Male Wistar rats (n = 502) were treated for 7 days pre-MI with losartan at a high dose (30 mg.kg(-1).day(-1)), progressively increasing dose (3 mg.kg(-1).day(-1) increased to 10 mg.kg(-1).day(-1) 10 days and 30 mg.kg(-1).day(-1) 20 days post-MI), or no treatment. Ambulatory systolic blood pressure and Holter monitoring were performed for 24 h post-MI. Echocardiography was done 30 days post-MI, and LV remodeling, cardiac hemodynamics, and fetal gene expression were assessed 38 days post-MI. High-dose losartan reduced 24-h post-MI survival compared with the progressive dose and control (21.9% vs. 36.6% and 38.1%, P = 0.033 and P = 0.009, respectively). This was associated with greater hypotension in the high dose and no change in ventricular arrhythmias in all groups. In 24-h post-MI survivors, the progressive dose group had reduced mortality from 24 h to 38 days (8.5% vs. 28.6% for control vs. 38.9% for high dose, P = 0.032 and P = 0.01, respectively). Survivors of both losartan groups demonstrated improved LV remodeling, cardiac hemodynamics, preserved GLUT-4, and reduced cardiac fetal gene expression. Pretreatment with ARBs does not reduce 24-h post-MI ventricular arrhythmias or survival, and high doses increase mortality by causing excessive hypotension. In 24-h post-MI survivors, progressively increasing doses of losartan have multiple beneficial effects, including improved survival. |
1,196 | High-resolution optical mapping of intramural virtual electrodes in porcine left ventricular wall. | It is believed that shock-induced intramural virtual electrodes (IVE) play a critical role in defibrillation. IVE were recently demonstrated in the porcine left ventricle (LV), but their origin remains unknown. Macroscopic optical mapping showed that strong shocks induce IVE of only one polarity, which contradicts theoretical predictions. It is hypothesized that IVE have a microscopic origin and that microscopic positive and negative IVE are spatially averaged during macroscopic optical mapping. This hypothesis was examined by mapping V(m) responses at the transmural LV surface with increased optical resolution.</AbstractText>Rectangular shocks (strength=2-48 V/cm; duration=10 ms) were applied across isolated coronary-perfused porcine LV preparations (n=7) during the action potential plateau and diastole. Shock-induced V(m) responses were measured at low resolution (LR; 1.2 mm/diode) and high resolution (HR; 0.11 mm/diode).</AbstractText>During plateau shocks with strength > or =20 V/cm, LR recordings demonstrated only negative DeltaV(m) extending to the cathodal preparation edge. In contrast, HR recordings from this area as well as from intramural locations revealed both positive and negative DeltaV(m) at all shock strengths. During diastolic shocks, only positive polarizations were observed at LR, but both positive and negative polarizations were detected at HR. In areas of negative polarization, large activation delays were found at HR, whereas LR recordings at these locations demonstrated fast activation.</AbstractText>High- and low-resolution optical mapping produced radically different patterns of shock-induced polarization and activation. The occurrence of positive and negative polarizations during plateau and diastolic shocks at high but not low resolution provides evidence for microscopic nature of IVE in LV wall.</AbstractText> |
1,197 | Defibrillation shock success estimation by a set of six parameters derived from the electrocardiogram. | It is well known that in some cases defibrillator shocks cannot terminate ventricular fibrillation (VF). Repeated failed shocks often may worsen subsequent response to therapy. This study assesses the ability of six parameters derived from the surface electrocardiogram (ECG) to predict defibrillation shock outcome. Using stepwise discriminant analysis, we obtained several discriminant functions, yielding different combinations of sensitivity and specificity for detection of pre-shock ECG segments corresponding to successful versus unsuccessful shocks. The study was performed consecutively for 3, 4 and 5 s ECG time intervals. The prediction accuracy of 72.3% (61.8% sensitivity and 79.6% specificity) with five parameters and 3 s VF segment analysis prior to defibrillation shock could be considered acceptable for possible practical application in automatic external defibrillators. |
1,198 | Real time detection of ventricular fibrillation and tachycardia. | The automatic external defibrillator (AED) is a lifesaving device, which processes and analyses the electrocardiogram (ECG) and delivers a defibrillation shock to terminate ventricular fibrillation or tachycardia above 180 bpm. The built-in algorithm for ECG analysis has to discriminate between shockable and non-shockable rhythms and its accuracy, represented by sensitivity and specificity, is aimed at approaching the maximum values of 100%. An algorithm for VF/VT detection is proposed using a band-pass digital filter with integer coefficients, which is very simple to implement in real-time operation. A branch for wave detection is activated for heart rate measurement and an auxiliary parameter calculation. The method was tested with ECG records from the widely recognized databases of the American Heart Association (AHA) and the Massachusetts Institute of Technology (MIT). A sensitivity of 95.93% and a specificity of 94.38% were obtained. |
1,199 | Surface ECG vector characteristics of organized and disorganized atrial activity during atrial fibrillation. | The aim of this study was to examine atrial organization from vectorcardiograms (VCGs) derived from the surface ECG of atrial fibrillatory waves.</AbstractText>We retrieved ECGs recorded during ventricular asystole from 22 patients with AF undergoing ablation of the AV junction. The synthesized VCG of each f-wave cycle of each ECG and its plane of best fit, described by azimuth and elevation angles relative to the frontal plane, were computed.</AbstractText>Fifteen of the 22 ECGs had at least 30% of the planes in a single 30-degree region of azimuth angles. Of these 15, 12 had the greatest percentage of planes with azimuth angles within 30 degrees of the sagittal plane; two were near the frontal plane; and one near the right anterior oblique plane.</AbstractText>Varying degrees of organization were observed from VCGs of fibrillatory waves with the more organized examples having planes predominately near the sagittal plane.</AbstractText> |
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