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  • 1
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: KOCHIADAKIS, G.E., et al.: Electrocardiographic Appearance of Old Myocardial Infarction in Paced Patients. This study evaluated the possibility of diagnosing chronic myocardial infarction in the presence of the pacing electrocardiogram. Forty-five patients with known myocardial infarction (anterior 23, inferior 22) and 26 healthy controls were studied. After coronary angiography, pacing was applied from the right ventricular apex, and the sensitivity, specificity, and average diagnostic accuracy of five criteria on the paced electrocardiogram were assessed: (1) Notching 0.04 second in duration in the ascending limb of the S wave of leads V3, V4, or V5 (Cabrera's sign); (2) Notching of the upstroke of the R wave in leads I, aVL, or V6 (Chapman's sign); (3) Q waves 〉 0.03 second in duration in leads I, aVL, or V6; (4) Notching of the first 0.04 second of the QRS complex in leads II, III, and aVF; (5) Q wave 〉 0.03 second in duration in leads II, III, and aVF. The most sensitive criteria, for anterior and inferior myocardial infarctions were Cabrera's and Chapman's (91.1 and 86.6%, respectively). All criteria had low specificity (range 42.3–69.2%). The combination of Cabrera's and Chapman's sign decreased the sensitivity to 77.7%, but increased specificity to 82.2%. The sensitivity and specificity of all the criteria were independent of the myocardial infarction site. In paced patients, the application of electrocardiographic criteria, and especially the combination of Cabrera and Chapman, provides useful clinical information in recognizing prior myocardial infarction but not in assigning the specific infarct site.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study examined the acute and long-term effects of DDD pacing on ergospirometric parameters and neurohormonal activity in patients with hypertrophic obstructive Cardiomyopathy (HOCM). We studied eight patients (five males), aged 56 ± 7 years, with HOCM refractory to drugs. In all patients a DDD pacemaker was implanted and programmed with an atrioventricular (AV) delay that insured full ventricular activation. The patients underwent echocardiographic examination and exercise stress testing before and 3 days, 3 months, and 12 months after pacemaker implantation. Oxygen consumption was measured at the anaerobic threshold (VO2AT) and peak exercise (pVO2). Atrial natriuretic peptide (ANP) and cyclic adenosine monophosphate (c-AMP) levels were measured concomitantly. Left ventricular outflow tract (LVOT) pressure gradient decreased significantly from 70 ± 18 to 25 ± 12 mmHg (P 〈 0.05) 3 days after pacing and remained unchanged at 3 and 12 months. pVO2 and VO2AT increased significantly, from 20.1 ± 3 to 23.4 ± 3 mL/kg/min and from 16 ± 3 to 17.8 ± 2 mL/kg/min, respectively (P 〈 0.05). This improvement continued up to 3 months, and then remained stable until the end of the 12-month follow-up period. ANP levels decreased at 3 days from 85.4 ± 5.7 to 75.4 ± 7.3 fmol/mL (P 〈 0.05), and remained unchanged over the 12 months. c-AMP levels did not change significantly after the onset of pacing. DDD pacing in patients with HOCM not only reduces the LVOT pressure gradient but also causes a significant early and long-term improvement in exercise capacity and neurohormonal profile.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The efficacy and safety of intravenous propafenone, amiodarone, or placebo were compared in the treatment of atrial fibrillation (AF) of recent onset (duration ≤ 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 IV 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Pacing and clinical electrophysiology 27 (2004), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Spectral analysis of heart rate variability was used to compare the changes in autonomic function during tilting in young and older patients with vasovagal syncope. Twenty-four young (age 28 ± 8 years) and 31 older (56 ± 5 years) patients with unexplained syncope and a positive tilt test and 25 controls (age 48 ± 12 years) were included in the study. Frequency-domain measurements of the low (LF) (0.06–0.15 Hz) and high (HF) (0.15–0.40 Hz) frequency bands and the ratio of LF to HF were computed from Holter recordings for 4-minute intervals before and immediately after tilting and just before the end in all groups. Syncopal patients showed a different pattern of response to tilting from controls in all spectral indexes. Young and older patients showed the same pattern of changes in all measurements, even though certain differences were observed. The LF after tilting reduced more in the older (-20 ± 7% vs -14 ± 5%, P 〈 0.001), while HF reduced more in young patients (-17 ± 8% vs -8 ± 3%, P 〈 0.001). Young patients showed mainly a cardioinhibitory type (71%) of response whereas a vasodepressor type response predominated (68%) in the older patients. The autonomic nervous system appears to play an important role in the pathophysiological mechanism of vasovagal syncope. This role is similar in young and in older patients and this should be taken into account in the therapeutic approach to the condition. Specific differences between age groups may be related to the type of vasovagal syncope.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148-5018 , U.S.A . : Blackwell Publishing
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this study was to investigate myocardial perfusion and adrenergic innervation in patients with intraventricular conduction disturbances and to detect any changes caused by alteration of the ventricular activation sequence as a result of right ventricular apical pacing. We studied 15 patients with right bundle branch block (RBBB) and left anterior fascicular block (LAFB), while 15 healthy individuals served as controls. All patients underwent planar and single-photon emission computed tomography (SPECT) myocardial imaging after intravenous infusion of 5mCi 123I-metaiodobenzylguanidine (123I-MIBG) and a SPECT thallium201 myocardial perfusion study before and 3 months after pacemaker implantation. The heart to mediastinum ratio was calculated during the 123I-MIBG study in order to assess the global cardiac sympathetic activity and was significantly smaller in patients than in controls (P 〈 0.001). Patients with RBBB and LAFB revealed regional adrenergic innervation defects, mostly in the inferior and posterior walls. After a medium-term pacing period, a redistribution of 123I-MIBG uptake was detected, with aggravation of adrenergic innervation defects in the apical and posterior walls and amelioration in septal and anterior walls. Five patients showed perfusion defects that remained unchanged after pacing. Two others displayed mild myocardial perfusion defects that did not exist before pacing. In conclusion, patients with RBBB and LAFB reveal global and regional disturbances of myocardial adrenergic innervation, which shows redistribution as a result of the altered propagation of the ventricular electrical activation. To a smaller degree these patients reveal myocardial perfusion disturbances in which pacing has a limited medium-term effect. (PACE 2003; 26:1202–1207)
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Spectral analysis of heart rate variability (HR V) 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. AII 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.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: MARKETOU, M.E., et al.: 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.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 23 (2000), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: SIMANTIRAKIS, E.N., et al.: Insertable Loop Recorder in Unmasking the Cause of Syncope. During the last few years closed loop recorders are being used increasingly in the investigation of unexplained syncope. Our patient had a 5-year history of pre- and syncopal episodes in which the usual invasive and noninvasive tests were nondiagnostic. Finally, a loop recorder was implanted that revealed the cause of the syncope a few days after implantation: a fast, sustained, ventricular tachycardia originating from the right ventricular outflow tract. Loop recorders will undoubtedly contribute toward the decrease in the percentage of undiagnosed syncope cases and possibly to the reduction of the investigation cost.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-7241
    Keywords: digoxin ; cardiopulmonary exercise testing ; heart rate variability ; baroreceptor sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
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