Impact of asynchronous ventricular activation on pro-inflammatory cytokines and oxidative stress in paced patients.
Explore the source record for details and available documents.
Cardiac Pacing, Artificial↗
Biomedical subjects
M E Marketou
Publications and source records attributed to M E Marketou.
Sensing issues related to the clinical use of implantable loop recorders.
AIMS: The newer insertable loop recorder device (Reveal Plus 9526, Medtronic Inc, Minneapolis MN, U.S.A.) is equipped with auto-activation capabilities. In this study we investigated whether the new device encounters sensitivity problems in the form of oversensing or undersensing. We also tested whether body position changes influence the sensed electrogram's amplitude, therefore affecting the device's autosensing ability. METHODS AND RESULTS: We enrolled 32 patients aged 58.1+/-11.7 years with a loop recorder implanted either in the left parasternal or in the heart's apex area, to investigate undiagnosed syncopal episodes after initial assessment. During the follow-up period (5.7+/-2.7 months), that began 6 months after the device implantation, we analysed 284 auto-recorded episodes (103 undersensed and 181 correctly sensed). No oversensing episodes were recorded. THE RECORDED QRS amplitude in five different body positions: supine, left and right lateral, sitting and standing was measured. No statistically significant changes were observed in the different postures. Even when patients were divided into subgroups according to implant site or the occurrence of undersensing episodes, no significant inter- or intra-group differences of the sensed electrogram were observed. CONCLUSION: Undoubtedly this device is the current gold standard for the diagnosis of unexplained syncope. In the population we studied though, the device faced undersensing problems. Consequently, the device should be equipped with more advanced software for QRS morphology recognition, to improve the diagnostic accuracy of the recorder.
Adult↗
Implantable loop recorder undersensing mimicking complete heart block.
The newer implantable loop recorders recently introduced (Reveal Plus. Medtronic Inc, Minneapolis, MN, U.S.A.). equipped with auto activation capabilities, are expected to expand our diagnostic abilities in the investigation of syncopal episodes. The case presented here is that of a man with pre-syncopal and syncopal episodes, without organic heart disease, in whom the device was auto-activated due to undersensing and the recorded strip imitated complete heart block. Increased attention should be given by the interpreter of the device's recordings to avoid false positive diagnoses that might lead to serious therapeutic actions.
Aged↗
Assessment of myocardial adrenergic innervation in patients with sick sinus syndrome: effect of asynchronous ventricular activation from ventricular apical stimulation.
OBJECTIVE: To investigate ventricular sympathetic innervation in patients with sick sinus syndrome and to detect regional deterioration of adrenergic innervation caused by asynchronous ventricular activation from right ventricular pacing. DESIGN: Prospective controlled study. SETTING: Tertiary cardiac referral centre. PATIENTS: 22 patients with sick sinus syndrome and indications for permanent dual chamber pacing; 20 healthy individuals as controls. INTERVENTIONS: All patients underwent myocardial imaging with planar and single photon emission computed tomography (SPECT) after an intravenous infusion of 5 mCi 123I-meta-iodobenzylguanidine (123I-MIBG) before and after pacemaker implantation. A SPECT thallium201 myocardial study was done during the same week as the 123I-MIBG study in all patients. MAIN OUTCOME MEASURES: The heart to mediastinum (H/M) ratio and washout rate were calculated during the 123I-MIBG study to assess the global cardiac sympathetic activity; the aim of the SPECT study was to investigate the regional distribution of adrenergic innervation. RESULTS: The H/M ratio was significantly smaller in the patients with sick sinus syndrome than in the controls (p < 0.001). In sick sinus syndrome there were regional adrenergic innervation defects, mostly in the inferior and apical walls. After a medium term pacing period, a redistribution of 123I-MIBG uptake was detected, with deterioration of adrenergic innervation in the inferior, apical, and posterior walls. The thallium201 myocardial perfusion study showed no change after three months of permanent pacing. CONCLUSIONS: Patients with sick sinus syndrome have global and regional disturbances of the adrenergic innervation of the left ventricular myocardium. These seem to deteriorate as a result of asynchronous electrical activation. The clinical significance of this finding requires further investigation.
3-Iodobenzylguanidine↗
Electrical storm due to amiodarone induced thyrotoxicosis in a young adult with dilated cardiomyopathy: thyroidectomy as the treatment of choice.
For a patient with idiopathic dilated cardiomyopathy, an implantable defibrillator, and amiodarone induced thyrotoxicosis associated with ventricular fibrillation storm. Medical therapy was ineffective. Thyroidectomy resulted in immediate control of the arrhythmia and permitted reinitiation of amiodarone. At 18-month follow-up, the patient remained euthyroid on amiodarone and ventricular arrhythmia free.
Adult↗
Atrial and ventricular refractoriness in paced patients; circadian variation and its relationship to autonomic nervous system activity.
AIMS: To examine whether atrial and ventricular effective refractory periods exhibit circadian variation and whether the latter is correlated with fluctuations in autonomic nervous system tone. METHODS AND RESULTS: We studied 24 patients aged 67.1 +/- 9.6 years, 11 of whom were paced for complete heart block and 13 for sick sinus syndrome. Atrial and ventricular effective refractory periods were measured bihourly over a 24-h period, using the pacemaker programming capabilities, at basic cycle lengths of 600 ms and 500 ms. During the same time period we evaluated autonomic nervous system activity in patients paced for complete heart block, expressed by spectral power indexes in low frequency and high frequency areas of heart rate variability. Atrial and ventricular effective refractory periods showed significant circadian variation at both basic cycle lengths, with the highest values occurring between 22:00 and 06:00. At times, the atrial and ventricular effective refractory periods of the patients with sick sinus syndrome differed significantly from those with complete heart block. Furthermore, atrial and ventricular effective refractory periods in patients with complete heart block exhibited a strong negative correlation with the low frequency/high frequency ratio. CONCLUSION: Our data show that atrial and ventricular effective refractory periods in DDD paced patients exhibit significant circadian variation that is strongly correlated with variations in autonomic nervous system activity in patients with complete heart block.
Aged↗
Dobutamine- vs exercise-induced ST segment elevation early after Q wave myocardial infarction. Prediction of functional recovery after revascularization.
AIMS: The association between stress-induced ST elevation and functional recovery following revascularization after myocardial infarction remains unclear. We assessed the relative accuracy of dobutamine- and exercise-induced ST elevation in Q wave leads in predicting functional recovery following revascularization, and we investigated the relationship of ST elevation to different wall motion responses to dobutamine. METHODS AND RESULTS: Thirty-nine patients underwent dobutamine stress echo and exercise test 8+/-2 days after Q wave myocardial infarction. All patients underwent angiography and subsequent revascularization. Follow-up echocardiograms were obtained 7+/-4 weeks after revascularization. Functional recovery was assessed by the difference between the baseline and the follow-up asynergy index. Nineteen patients (48%) developed dobutamine- and exercise-induced ST elevation. There was significant agreement between the tests (k=0.58, P<0.001). We found a significant correlation between dobutamine and exercise-induced ST elevation with functional recovery following revascularization (r=0. 45, P<0.005 and r=0.7, P<0.001, respectively). The parameters with the highest predictive value for functional recovery were: (a) the biphasic response during dobutamine infusion, (b) the development of ST elevation in both tests, and (c) the development of exercise-induced ST elevation in more than three leads. CONCLUSION: There is a strong association between dobutamine- and exercise-induced ST elevation with functional recovery following revascularization. Exercise-induced ST elevation in more than three leads and a biphasic response during dobutamine infusion accurately predict functional recovery.
Angioplasty, Balloon, Coronary↗
Autonomic nervous system activity before and during episodes of myocardial ischemia in patients with stable coronary artery disease during daily life.
Spectral analysis of heart rate variability (HRV) was used to assess changes in the autonomic nervous system (ANS) 10 minutes before, during, and 10 minutes after 110 ischemic episodes (IEs) in 38 patients (25 men, age 61 +/- 10 years) with stable coronary artery disease. In 26 of 77 diurnal IEs (07:00-22:59) there were no changes in the spectral indexes (LF and HF) during the study period. In the remainder there was an increase in the LF:HF ratio due to HF withdrawal that started before the onset of the IE. All 33 nocturnal episodes also showed an increase in the LF:HF ratio, which was due not only to HF withdrawal, but also to a simultaneous increase in LF. Although it is not the only cause, the ANS plays a significant role in triggering IEs during daily life in patients with stable coronary artery disease. The common factor in all such episodes is a gradual withdrawal of parasympathetic tone.
Activities of Daily Living↗
Amiodarone, sotalol, or propafenone in atrial fibrillation: which is preferred to maintain normal sinus rhythm?
UNLABELLED: This randomized study compared the efficacy and safety of amiodarone, propafenone and sotalol in the prevention of atrial fibrillation. METHODS: The population consisted of 214 consecutive patients (mean age 64 +/- 8 years, 106 men) with recurrent symptomatic atrial fibrillation. After restoration of sinus rhythm, patients were randomized to amiodarone (200 mg/day), propafenone (450 mg/day) or sotalol (320 +/- 20 mg/day). Follow-up evaluations were conducted at 1, 2, 4 and 6 months, and at 3-month intervals thereafter. The proportion of patients developing recurrent atrial fibrillation and/or experiencing unacceptable adverse effects was measured in the three groups by the Kaplan-Meier method. RESULTS: Recurrent atrial fibrillation occurred in 25 of the 75 patients treated with amiodarone compared to 51 of the 75 patients treated with sotalol and 24 of the 64 patients treated with propafenone. Fourteen patients treated with amiodarone, five with sotalol, and one with propafenone experienced adverse effects while in sinus rhythm, necessitating discontinuation of treatment (P < 0.001 for amiodarone and propafenone vs sotalol). The difference between amiodarone and propafenone was statistically nonsignificant when all events were included in the analysis. However, if the analysis was limited to recurrent atrial fibrillation events, amiodarone was more effective than propafenone (P < 0.05). CONCLUSIONS: Amiodarone and propafenone were superior to sotalol in maintaining long-term normal sinus rhythm in patients with atrial fibrillation. Amiodarone tended to be superior to propafenone, though its long-term efficacy was limited by adverse side effects.
Administration, Oral↗
Low dose amiodarone and sotalol in the treatment of recurrent, symptomatic atrial fibrillation: a comparative, placebo controlled study.
OBJECTIVE: To assess and compare the safety and efficacy of amiodarone and sotalol in the treatment of patients with recurrent symptomatic atrial fibrillation. DESIGN: Prospective, randomised, single blind, placebo controlled study. SETTING: Tertiary cardiac referral centre. PATIENTS: 186 consecutive patients (97 men, 89 women; mean (SD) age, 63 (10) years) with recurrent, symptomatic atrial fibrillation. INTERVENTIONS: 65 patients were randomised to amiodarone, 61 to sotalol, and 60 to placebo. Patients receiving amiodarone were maintained at a dose of 200 mg/day after a 30 day loading phase. The sotalol dose was 160-480 mg daily, as tolerated. MAIN OUTCOME MEASURES: Recurrence of atrial fibrillation or side effects. RESULTS: In the amiodarone group, 31 of the 65 patients developed atrial fibrillation after an average of six months, while 15 (11 in sinus rhythm and four in atrial fibrillation) experienced significant side effects after an average of 16 months. In the sotalol group, relapse to atrial fibrillation occurred in 47 of the 61 patients after an average of eight months; three experienced side effects during the titration phase. In the placebo group, 53 of the 60 patients developed atrial fibrillation after an average of four months (p < 0.001 for amiodarone and sotalol v placebo; p < 0.001 for amiodarone v sotalol). CONCLUSIONS: Both amiodarone and sotalol can be used for the maintenance of normal sinus rhythm in patients with symptomatic atrial fibrillation. Amiodarone is more effective but causes more side effects.
Aged↗
Impact of chronic DDD pacing on time-domain indexes of heart rate variability in patients with hypertrophic obstructive cardiomyopathy.
The aim of this study was to examine whether DDD pacing affects time-domain indexes of heart rate variability (HRV) in patients with hypertrophic obstructive cardiomyopathy (HOCM). We studied 11 patients (7 men, age 52 +/- 8 years) with HOCM refractory to drugs. In all patients a DDD pacemaker was implanted and the atrioventricular delay was programmed to ensure a full ventricular activation sequence. Time-domain indexes of HRV (mean NN, SDANN, SDNN, SD, rMSSD, pNN50) were determined from 24-hour Holter recordings 3 days before and 1 year after pacemaker implantation. The pacemaker was turned off during the second recordings. The same indexes were determined in ten healthy controls at the same time points. The controls showed no significant differences in any of the measured parameters between the two time points. The HOCM patients showed an increase in SD (from 27 +/- 13 to 41 +/- 13 ms, P < 0.001), rMSSD (from 18 +/- 5 to 32 +/- 8 ms, P < 0.001), and pNN50 (from 1.03 +/- 1.06 to 8.52 +/- 4.84%, P < 0.0001). As a result, the values of these three parameters, which were lower in the HOCM patients than in the controls before pacing, were restored to normal levels by the end of the study. In conclusion, our findings indicate that long-term pacing in HOCM patients restores the sympathovagal balance in the heart by increasing vagal activity.
Atrioventricular Node↗
Low-dose amiodarone versus sotalol for suppression of recurrent symptomatic atrial fibrillation.
To compare the safety and efficacy of amiodarone and sotalol in the treatment of patients with recurrent symptomatic atrial fibrillation (AF), 70 patients were entered into a randomized, double-blind study. Of these, 35 received amiodarone and 35 sotalol. There were no significant differences in baseline clinical characteristics between groups. Patients with ejection fraction < 40% or clinically significant heart disease were excluded. Patients randomized to amiodarone began with 800 to 1,600 mg/day for 7 to 14 days orally. After the initial loading phase, the drug dose was tapered to maintenance levels over 7 to 12 days; thereafter, therapy was generally maintained at a dosage of 200 mg/day. The sotalol dosage was 80 to 360 mg twice daily, as tolerated. Follow-up clinical evaluations were conducted at 1, 2, 4, 6, 9, and 12 months. The proportion of patients remaining in sinus rhythm on each agent was calculated for the 2 groups using the Kaplan-Meier method. Ten of the 35 patients who were taking amiodarone developed AF during the 12-month observation period, compared with 21 of the 35 who were taking sotalol (p = 0.008). No significant effect of sex, age, left atrial size, or type of AF could be detected that increased the risk of development of AF. We conclude that both amiodarone and sotalol can be used for the maintenance of normal sinus rhythm in patients with recurrent symptomatic AF but that amiodarone is the more effective of the 2 drugs for this purpose.
Amiodarone↗
Spectral analysis of heart rate variability during tilt-table testing in patients with vasovagal syncope.
Spectral analysis of heart rate variability was used to assess changes in autonomic function in 44 patients with vasovagal syndrome and 20 normal controls before and during postural tilt and to attempt to relate such changes to specific types of haemodynamic response to tilt. Frequency domain measurements of the high (HF) and low (LF) frequency bands and the ratio LF/HF were derived from Holter recordings, computed by Fast Fourier Analysis for 4 min intervals immediately before tilt testing, immediately after tilting and just before the end of the test. In the syncopal patients the mean values of LF and HF decreased significantly in response to tilting, while the LF/HF ratio remained constant. All parameters showed a statistically significant increase just before the onset of syncope. In the control group there was an increase in the LF and LF/HF ratio and a decrease in the HF immediately after tilting. The three subgroups of patients had similar patterns of changes in autonomic activity. The results of this study show that syncopal patients have a different pattern of response to the tilting test. The pathological mechanism leading to vasovagal syncope appears to be independent of the specific type of haemodynamic response to tilt testing.
Autonomic Nervous System↗
Effects of long-term digoxin therapy on heart rate variability, baroreceptor sensitivity, and exercise capacity in patients with heart failure.
We evaluated the effects of long-term digoxin therapy on exercise capacity and on physiological parameters reflecting autonomic tone in 23 patients with mild to moderate heart failure. Before and after maintenance digoxin treatment, all patients underwent cardiopulmonary exercise testing and indexes of heart rate variability (HRV) and baroreceptor sensitivity (BRS) were measured. Long-term digoxin therapy significantly (P < 0.05) increased time domain indexes (rMSSD, pNN50) which reflect parasympathetic activity (from 30 +/- 16 to 37 +/- 14 and from 8 +/- 9 to 12 +/- 7, respectively). High-frequency (HF) and low-frequency (LF) power spectral components also showed a significant increase (from 4.5 +/- 1 to 5.1 +/- 1 and from 5.4 +/- 1 to 5.8 +/- 1, respectively), but the ratio LF/HF decreased, indicating a predominance of vagal activity. The magnitude of these changes exhibited a strong negative Pearson correlation coefficient when compared with initial values before treatment. BRS increased from 2.95 +/- 1.2 to 5.32 +/- 3 ms/mmHg (P < 0.05). Oxygen consumption at peak exercise and at the anerobic threshold increased significantly (from 17 +/- 3 to 19 +/- 3 mL/kg/min and from 14.7 +/- 3 to 16.5 +/- 3 mL/kg/min, respectively). A persistent negative correlation was found between initial values of HRV and the magnitude of changes in exercise capacity. These findings show that long-term digoxin therapy increases vagal activity and improves exercise capacity in patients with mild to moderate heart failure and seems to exert a more marked therapeutic effect on patients with poorer initial autonomic function.
Aged↗
Intravenous propafenone versus intravenous amiodarone in the management of atrial fibrillation of recent onset: a placebo-controlled study.
UNLABELLED: The efficacy and safety of intravenous propafenone, amiodarone, or placebo were compared in the treatment of atrial fibrillation (AF) of recent onset (duration < or = 48 hours). METHODS: 143 patients (77 men, mean age 63 +/- 12 years) were studied, of whom 46 received propafenone (2 mg/kg over 15 minutes followed by 10 mg/kg over the next 24 hours), 48 received amiodarone (300 mg intravenously over 1 hour, followed by 20 mg/kg over the next 24 hours, plus 1,800 mg/day orally, in 3 divided doses), and 49 received placebo (the equivalent amount of saline i.v. over 24 hours). Digoxin was administered to all patients who had not previously received it. RESULTS: Conversion to normal sinus rhythm occurred in 36 of 46 patients (78.2%) receiving propafenone, in 40 of 48 patients (83.3%) receiving amiodarone, and in 27 of the 49 (55.10%) controls (P < 0.02, drug vs placebo, between drugs NS). The mean time to conversion was 2 +/- 3 hours for propafenone, 7 +/- 5 hours for amiodarone, and 13 +/- 9 for placebo (P < 0.05). Patients who converted had smaller atria than those who did not (diameter: 42.7 +/- 5 vs 47.2 +/- 7 mm, P < 0.001 for all). Treatment was discontinued in one patient in the amiodarone group because of an allergic reaction and in two patients in the propafenone group because of excessive QRS widening. No side effects were observed in the placebo group. CONCLUSIONS: Both drugs tested intravenously were equally effective and safe for the rapid conversion of recent-onset atrial fibrillation to sinus rhythm. However, propafenone offered the advantage of more rapid conversion than amiodarone.
Amiodarone↗