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Amiodarone Therapy (amiodarone + therapy)
Selected AbstractsEffect of Chronic Amiodarone Therapy on Excitable Gap During Typical Human Atrial FlutterJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2004PHILIPPE MAURY M.D. Introduction: Class I antiarrhythmic drugs increase duration of the excitable gap (EG) during typical atrial flutter whereas intravenous class III drugs decrease the EG. The effect of chronic oral amiodarone therapy on the EG is unknown. Methods and Results: EG was prospectively determined by introducing a premature stimulus and analyzing the response pattern during typical atrial flutter in 30 patients without antiarrhythmic drugs and in 20 patients under chronic oral amiodarone therapy. EG was calculated by the difference between the longest coupling interval leading to resetting and the effective atrial refractory period (EARP). A fully EG was defined by the portion of EG where the response curve of the return cycles was flat. A partially EG was defined by the portion of EG where the return cycle increases while coupling interval decreases. A resetting response curve was constructed by plotting the duration of the return cycle against the value of the coupling interval. Cycle length (CL; 222 ± 17 vs 267 ± 20 msec, P < 0.0001), EARP (128 ± 16 vs 152 ± 18 msec, P < 0.0001), and EG (54 ± 19 vs 70 ± 21 msec, P = 0.01) were significantly longer in patients taking amiodarone than in controls. Compared to CL, the relative part of the EARP (57 ± 7 vs 57 ± 6%, P = 0.96) and EG (24 ± 7 vs 26 ± 8%, P = 0.41) were comparable in both groups. The fully EG was larger in patients under chronic amiodarone therapy than in controls (39 ± 21 vs 26 ± 20 msec, P = 0.03). Neither duration of the partially EG (28 ± 15 vs 31 ± 15 msec, P = 0.42) nor slope of the ascending portion of the resetting response curve (1.15 ± 0.5 vs 1.13 ± 0.4 msec/msec, P = 0.71) differed between the two groups. Conclusion: EG in patients under chronic amiodarone therapy is significantly larger than in controls, mainly because of a longer fully EG. This observation may be explained by opposite effects on conduction velocity and refractoriness. [source] Effects of Isoproterenol and Amiodarone on the Double Potential Interval After Ablation of the Cavotricuspid IsthmusJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2003HIROSHI TADA M.D. Introduction: A corridor of double potentials along the ablation line has been recognized to be an indicator of complete cavotricuspid isthmus block. Isoproterenol is used to confirm cavotricuspid isthmus block, but the effects of isoproterenol on the double potential interval (DPI), either in the absence or presence of amiodarone, are unknown. Methods and Results: Thirty-two patients with isthmus-dependent atrial flutter underwent successful ablation of the cavotricuspid isthmus. The procedure was performed in the drug-free state in 23 patients, and 2 to 7 days after discontinuation of chronic amiodarone therapy in 9 patients. Electrograms recorded along the ablation line before and during isoproterenol infusion were analyzed after isthmus block was achieved. Double potentials were recorded along the entire ablation line upon achievement of complete isthmus block in all patients. The DPI in 9 patients treated with amiodarone was longer than in the other patients (147 ± 32 msec vs 119 ± 19 msec, P < 0.001). The DPI increased as the pacing cycle length shortened in patients treated with amiodarone, but not in the other patients. At all pacing cycle lengths, isoproterenol shortened the DPI to a greater extent in the patients treated with amiodarone than in the other patients. Conclusion: Amiodarone results in rate-dependent prolongation of the DPI during coronary sinus pacing after ablation of the cavotricuspid isthmus. Isoproterenol shortens the DPI despite the presence of complete isthmus block, and this effect is accentuated in the presence of amiodarone. (J Cardiovasc Electrophysiol, Vol. 14, pp. 935-939, September 2003) [source] Improved Survival of Cardiac Transplantation Candidates with Implantable Cardioverter Defibrillator Therapy:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2003Role of Beta-Blocker or Amiodarone Treatment Introduction: Survival in patients awaiting cardiac transplantation is poor due to the severity of left ventricular dysfunction and the susceptibility to ventricular arrhythmia. The potential role of implantable cardioverter defibrillators (ICDs) in this group of patients has been the subject of increasing interest. The aims of this study were to ascertain whether ICDs improve the survival rate of patients on the waiting list for cardiac transplantation and whether any improvement is independent of concomitant beta-blocker or amiodarone therapy. Methods and Results: Data comprised findings from 310 consecutive patients at a single center who were evaluated and deemed suitable for cardiac transplantation and placed on the waiting list. Kaplan-Meier actuarial approach was used for survival analysis. Survival analysis censored patients at time of transplantation or death. Of the 310 patients, 111 (35.8%) underwent successful cardiac transplantation and 164 (52.9%) died while waiting; 35 patients remain on the waiting list. Fifty-nine (19%) patients had ICD placement for ventricular arrhythmias prior to or after being listed. Twenty-nine (49.1%) ICD patients survived until cardiac transplantation, 13 (22%) patients died, and 17 (28.8%) remain on the waiting list. Among non-ICD patients, 82 (32.7%) received transplants, 151 (60.2%) died, and 18 (7.2%) remain on the waiting list. Survival rates at 6 months and 1, 2, 3, and 4 years were better for all ICD patients compared to non-ICD patients (log-rankx2, P = 0.0001). By multivariate analysis, ICD therapy and beta-blocker treatment were the strongest predictors of survival. Further, ICD treatment was associated with improved survival independent of concomitant treatment with beta-blocker or amiodarone. Among ICD and non-ICD patients treated with a beta-blocker or amiodarone, survivals at the 1 and 4 years were 93% vs 69% and 57% vs 32%, respectively (log-rankx2, P = 0.003). Conclusion: ICD therapy is associated with improved survival in high-risk cardiac transplant candidates, and ICD benefit appears to be independent of concomitant treatment. (J Cardiovasc Electrophysiol, Vol. 14, pp. 578-583, June 2003) [source] Moricizine Induced Increase in Pacing ThresholdPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p1 2003JOHN P. GIROD GIROD, J.P., et al.: Moricizine Induced Increase in Pacing Threshold. A 72-year-old woman who was experiencing incessant ventricular tachycardia and recurrent automatic implantable cardioverter defibrillator (AICD) firing despite amiodarone therapy was referred to the Cleveland Clinic Foundation. Myocardial ischemia and infarction were ruled out by standard means. Several antiarrhythmic medications were tried previously without success. Moricizine, 200 mg three times daily, was initiated and controlled the ventricular tachycardia. However, after the dose of moricizine was titrated upward, the patient became symptomatically bradycardic and the ECG exhibited 2:1 block of her paced rhythm and an increased ventricular pacing threshold. (PACE 2003; 26[Pt. I]:110,111) [source] Fetal supraventricular tachycardia: a role for amiodarone as second-line therapy?PRENATAL DIAGNOSIS, Issue 2 2003Jean-Marie Jouannic Abstract Objective The aim of this study was to evaluate the role of amiodarone for the prenatal treatment of hydropic fetuses with supraventricular tachycardia. Methods A group of 26 hydropic fetuses with supraventricular tachycardia was studied retrospectively. Results Twenty-five fetuses received transplacental treatment. The overall prenatal conversion rate was 60%. Nine fetuses were converted to sinus rhythm using either flecainide (n = 7) or amiodarone (n = 2) as first line therapy, whilst digoxin alone or in association with sotalol failed to restore sinus rhythm in all cases. After first-line therapy, supraventricular tachycardia persisted in 10 fetuses. Nine fetuses received amiodarone alone or in association with digoxin as second-line therapy, five of whom were converted to sinus rhythm. Among the 11 live neonates treated by amiodarone in utero, 2 (17%) presented an elevated thyroid stimulating hormone at day 3,4. These two infants received thyroid hormone substitution therapy and had a normal outcome. Conclusion When first-line therapy fails to restore sinus rhythm in hydropic fetuses with supraventricular tachycardia, amiodarone therapy should be considered as it allows a substantial number of fetuses to be converted prenatally. Copyright © 2003 John Wiley & Sons, Ltd. [source] Beta-blocker Utilization and Outcomes in Patients Receiving Cardiac Resynchronization TherapyCLINICAL CARDIOLOGY, Issue 7 2010Andrew Voigt MD Introduction Optimal pharmacologic therapy (OPT) is considered a prerequisite to consideration for cardiac resynchronization therapy (CRT). Hypothesis Medications such as beta-blockers (BB) with demonstrated benefit in heart failure (HF) are being under utilized in patients receiving CRT. Methods Consecutive patients receiving a CRT-capable defibrillator in 2004 at a tertiary care center for standard indications were studied. Clinical data and medications upon hospital discharge were recorded. Patients were followed for endpoints of death or transplantation. Results Of 177 patients receiving a CRT device, 129 (73%) received BB therapy (group 1). Of the 48 patients not on BBs (group 2), relative contraindications were documented in 21 (allergy in 3, hypotension or inotrope-dependent HF in 4, chronic obstructive pulmonary disease [COPD] in 6, and amiodarone therapy in 8). The remaining 27 patients (group 3) did not receive BB therapy despite absence of documented justification. Compared to group 1, group 3 patients were similar in terms of clinical characteristics and angiotensin-converting enzyme inhibitor (ACEI) use, but were less likely to be on statin therapy. Patients were followed for a mean of 19.9 ± 9.2 mo. After adjusting for age, QRS duration, creatinine, left ventricular ejection fraction (LVEF), statin use, and presence of ischemic HF etiology, patients not receiving BB therapy in the absence of contraindication had increased risk of death or transplantation (odds ratio [OR]: 3.1, p = 0.043). Conclusions Absence of BB therapy appears to be independently associated with poor outcome in CRT recipients. These results suggest that a crucial component of OPT may be underutilized in a population of HF patients receiving CRT. Copyright © 2009 Wiley Periodicals, Inc. [source] Benzofuran derivatives and the thyroidCLINICAL ENDOCRINOLOGY, Issue 1 2009T. S. Han Summary Amiodarone and dronedarone are two clinically important benzofuran derivatives. Amiodarone has been used widely for treating resistant tachyarrhythmias in the past three decades. However amiodarone and its main metabolically active metabolite desethylamiodarone can adversely affect many organs, including the thyroid gland. Amiodarone-induced thyroid disorders are common and often present as a management challenge for endocrinologists. The pathogenesis of amiodarone-induced thyroid dysfunction is complex but the inherent effects of the drug itself as well as its high iodine content appear to play a central role. The non-iodinated dronedarone also exhibits anti-arrhythmic properties but appears to be less toxic to the thyroid. This review describes the biochemistry of benzofuran derivatives, including their pharmacology and the physiology necessary for understanding the cellular mechanisms involved in their actions. The known effects of these compounds on thyroid action are described. Recommendations for management of amiodarone-induced hypothyroidism and thyrotoxicosis are suggested. Dronedarone appears to be an alternative but less-effective anti-arrhythmic agent and it does not have adverse effects on thyroid function. It may have a future role as an alternative agent in patients being considered for amiodarone therapy especially those at high risk of developing thyroid dysfunction but not in severe heart failure. [source] | ||||||||||