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Biomedical subjects

E Crystal

Publications and source records attributed to E Crystal.

13 recordsLinked to original sources
PubMed2005

Effects of magnesium on atrial fibrillation after cardiac surgery: a meta-analysis.

OBJECTIVES: To assess the efficacy of the administration of magnesium as a method for the prevention of postoperative atrial fibrillation (AF) and to evaluate its influence on hospital length of stay (LOS) and mortality. METHODS: Literature search and meta-analysis of the randomised control studies published since 1966. RESULTS: 20 randomised trials were identified, enrolling a total of 2490 patients. Study sample size varied between 20 and 400 patients. Magnesium administration decreased the proportion of patients developing postoperative AF from 28% in the control group to 18% in the treatment group (odds ratio 0.54, 95% confidence interval (CI) 0.38 to 0.75). Data on LOS were available from seven trials (1227 patients). Magnesium did not significantly affect LOS (weighted mean difference -0.07 days of stay, 95% CI -0.66 to 0.53). The overall mortality was low (0.7%) and was not affected by magnesium administration (odds ratio 1.22, 95% CI 0.39 to 3.77). CONCLUSION: Magnesium administration is an effective prophylactic measure for the prevention of postoperative AF. It does not significantly alter LOS or in-hospital mortality.

Anti-Arrhythmia Agents↗
PubMed2004

Stimulation of unidirectional pulses in excitable systems.

Using a judicious spatial shape of input current pulses (and electrodes), responses of an excitable system (FitzHugh-Nagumo) appear as unidirectional pulses (UDP's) instead of bidirectional ones (in one dimension) or circular ones (in two dimensions). The importance of the UDP's for a possible mechanism for pinpointing the reentry cycle position and for a possible use in tachycardia suppression is discussed.

Action Potentials↗
PubMed2004

Interventions for preventing post-operative atrial fibrillation in patients undergoing heart surgery.

BACKGROUND: Post-operative atrial fibrillation is a common complication of cardiac surgery and has been associated with increased incidence of other complications including post-operative stroke, increased hospital length of stay and increased cost of hospitalisation. Prevention of atrial fibrillation is a reasonable clinical goal and, consequently, many randomised trials have evaluated the effectiveness of pharmacological and non-pharmacological interventions. We systematically reviewed the literature and prepared meta-analyses to better understand the role and effects of various prophylactic therapies against post-operative atrial fibrillation. OBJECTIVES: To assess the effects of pharmacological and non-pharmacological interventions for preventing post-cardiac surgery atrial fibrillation. SEARCH STRATEGY: We searched CENTRAL, MEDLINE, EMBASE and CINAHL from earliest achievable date to June 2003. We hand searched references from reports and earlier reviews. We searched abstract books and CD-ROMs from annual scientific meetings of American College of Cardiology, American Heart Association, North American Society of Pacing and Electrophysiology and European Heart Organization between 1997-2003. No language restrictions were applied. SELECTION CRITERIA: Randomised controlled trials comparing pharmacological interventions or non-pharmacological interventions with control treatment, placebo or usual care for the prevention of post-operative atrial fibrillation in post-coronary artery bypass grafting or combined CABG and valvular surgery. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Fifty eight studies were included with a total of 8565 participants. Interventions included were amiodarone, beta blockers, solatol and pacing. Results favoured treatment for post-operative atrial fibrillation. The data for stroke favoured treatment by a non-significant effect size of 0.81, 95% confidence interval 0.51 to 1.28. Similarly, a positive indication for length of stay was derived but it too was not significant with a weighted mean difference of -0.66, 95% confidence interval -0.95 to -0.37. A positive result for cost of hospitalisation in favour of treatment was achieved, but the statistic is not significant due to low power and large standard deviations: a weighted mean difference of -2717, 95% confidence interval 7518 to 2084. Beta-blockers had the greatest magnitude of effect across 28 trials (4074 patients) with an odds ratio (random) of 0.35, 95% confidence interval 0.26 to 0.49. Across all treatment, the odds ratio favoured treatment with a ratio (random) of 0.43, 95% confidence interval 0.37 to 0.51. REVIEWERS' CONCLUSIONS: Intervention is favoured across the three pharmacological interventions studied and the one non-pharmacological intervention, pacing. The length of stay data favoured treatment (-0.66, 95% confidence interval -0.95 to -0.37).

Adrenergic beta-Antagonists↗
PubMed2004

Physiologic pacing: where pacing mode selection reflects the indication.

Results of recent trials suggest that in patients with left ventricular dysfunction, interventricular synchrony is possibly more important than atrioventricular synchrony. In patients with AV block and conduction system disease, alternatives to right ventricular apical pacing are therefore needed.

Arrhythmias, Cardiac↗
PubMed2002

Improved prognosis of patients presenting with clinical markers of spontaneous reperfusion during acute myocardial infarction.

OBJECTIVE: To describe the clinical features, management, and prognosis of patients presenting with clinical markers of spontaneous reperfusion (SR) during acute myocardial infarction (AMI). DESIGN: Cohort study. SETTING: National registry of 26 coronary care units. PATIENTS: 2382 consecutive patients with AMI. MAIN OUTCOME MEASURES: Patient characteristics, management, and mortality. RESULTS: The incidence of SR was 4% of patients (n = 98) compared with thrombolytic treatment (n = 1163, 49%), primary angioplasty (n = 102, 4%), and non-reperfusion (n = 1019, 43%). SR patients were more likely to develop less or no myocardial damage as indicated by a higher percentage of non-Q wave AMI (58% v 32%, 47%, and 44%, respectively, p < 0.0001), aborted AMI (25% v 9%, 8%, and 12%, p < 0.001), and lower peak creatine kinase (503 v 1384, 1519, and 751 IU, p < 0.0001). SR patients, however, were more likely to develop recurrent ischaemic events (35% v 17%, 12%, and 16%, respectively; p < 0.001) and subsequently were more likely to be referred to coronary angiography (67%), angioplasty (41%), or bypass surgery (16%, p < 0.001). Mortality at 30 days (1% v 8%, 7%, and 13%, respectively, p < 0.0001) and one year (6% v 11%, 12%, and 19%, p < 0.0001) was significantly lower for SR patients than for the other subgroups. By multivariate analysis, SR remained a strong determinant of 30 day survival (odds ratio (OR) 0.16, 95% confidence interval (CI) 0.01 to 0.74). At one year, the association between SR and survival decreased (OR 0.49, 95% CI 0.18 to 1.13). CONCLUSIONS: Clinical markers of SR are associated with greater myocardial salvage and favourable prognosis. The vulnerability of SR patients to recurrent ischaemic events suggests that they need close surveillance and may benefit from early intervention.

Angioplasty, Balloon, Coronary↗
PubMed2000

Patterns of accelerated junctional rhythm during slow pathway catheter ablation for atrioventricular nodal reentrant tachycardia: temperature dependence, prognostic value, and insights into the nature of the slow pathway.

INTRODUCTION: Although accelerated junctional rhythm (AJR) is a known marker for successful slow pathway (SP) ablation sites, AJR may just be a regional effect of the anisotropic conduction properties of this area of the heart. We believe that detailed assessment of the AJR might provide insight into the SP specificity of this AJR and perhaps the nature of the SP itself. METHODS AND RESULTS: Our ablation protocol consisted of 30-second, 70 degrees C temperature-controlled ablation pulses with assessment after each pulse. Serial booster ablations were performed at the original successful site and at least 2 to 3 nearby sites to assess for residual AJR after the procedure in 50 consecutive SP ablations. We defined three distinct patterns of AJR: continuous AJR that persisted until the end of energy delivery (group I, 25 patients); alternating or "stuttering" AJR that persisted throughout energy delivery (group II, 9 patients); and AJR that ended abruptly during energy delivery (group III, 16 patients). Mean ablation temperatures in the three groups was 57 degrees+/-5 degrees C, 54 degrees+/-5 degrees C, and 63 degrees+/-5 degrees C, respectively (P = 0.0002 for groups I and II vs group III). Ten of 34 (29%) patients in groups I and II ("low-temperature ablation") exhibited residual SP (jump and/or single echo beats) despite tachycardia noninducibility, and 25 of 34 (73%) patients had residual AJR during the booster ablations, but neither of these was seen in any group III patients. CONCLUSION: Ablation temperature correlates with the pattern of AJR produced during SP ablation. That higher temperature lesions simultaneously abolish all SP activity as well as the focus of AJR suggests that this AJR is specific for the SP and is not a nonspecific regional effect.

Adult↗
PubMed1999

Contribution of stenting to the results of rescue PTCA.

Failed thrombolysis in acute myocardial infarction (AMI) is associated with increased mortality. Controversial benefit of rescue percutaneous transluminal coronary angioplasty (PTCA) in these setting has been published. The feasibility, safety, and contribution of stenting to the outcome of AMI patients treated with this strategy is unknown. We studied the angiographic result and clinical outcome of 33 patients with failed thrombolysis referred for rescue angioplasty. Twenty-three patients had stenting and 10 patients did not have stenting. Both groups had similar clinical and angiographic characteristics. Stent indications were nonoptimal result, 40%; bailout, 40%; elective, 20%. Angiographic success was 100% with stent vs. 91% with balloon alone (P < 0.8). Postprocedure residual stenosis was 1.5% (0%-10%) with stent vs. 18.05% (0%-30%) with balloon alone (P < 0.01). Thirty-day outcome with and without stent was mortality, 0% vs. 13% (P < 1.0); reinfarction, 10% vs. 0% (P < 0.30); target vessel revascularization, 0% vs. 21% (P < 0.21). The 6-month mortality was 0% with stent vs. 14% (P < 0.5). We conclude that stenting during rescue angioplasty is feasible, safe, and is associated with better immediate angiographic results. Although no obvious clinical benefit was found, a potential decrease in the revascularization rate was suggested.

Angioplasty, Balloon, Coronary↗
PubMed1999

Cardiac output-based versus empirically programmed AV interval--how different are they?

AIMS: To compare empirically programmed and cardiac output-based programming of atrioventricular (AV) interval in patients with dual chamber pacemakers. METHODS AND RESULTS: In 19 patients with implanted dual chamber pacemakers due to AV block but otherwise normal hearts, cardiac output was assessed using an impedance cardiography device. In all patients, the AV interval had been previously programmed empirically by an experienced cardiologist. Cardiac output was estimated at AV intervals from 50 to 250 ms during VDD pacing. AV intervals adjusted by serial cardiac output estimations caused a rise in cardiac output in 84% of patients. The maximal achievable cardiac output was greater by 12% +/- 8% (range 0-32%), P < 0.001, than was observed with empirically programmed AV intervals. CONCLUSIONS: In patients with dual chamber pacemakers due to AV block and otherwise normal hearts, empirically selected AV intervals may lead to compromise of cardiac haemodynamics. Optimal AV intervals may be selected by serial cardiac output measurements.

Atrioventricular Node↗