ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundAtrial fibrillation (AF) causes substantial morbidity. It is uncertain whether AF is associated with excess mortality independent of associated cardiac conditions and risk factors.Methods and Results-We examined the mortality of subjects 55 to 94 years of age who developed AF during 40 years of follow-up of the original Framingham Heart Study cohort. Of the original 5209 subjects, 296 men and 325 women (mean ages, 74 and 76 years, respectively) developed AF and met eligibility criteria. By pooled logistic regression, after adjustment for age, hypertension, smoking, diabetes, left ventricular hypertrophy, myocardial infarction, congestive heart failure, valvular heart disease, and stroke or transient ischemic attack, AF was associated with an OR for death of 1.5 (95% CI, 1.2 to 1.8) in men and 1.9 (95% CI, 1.5 to 2.2) in women. The risk of mortality conferred by AF did not significantly vary by age. However, there was a significant AF-sex interaction: AF diminished the female advantage in survival. In secondary multivariate analyses, in subjects free of valvular heart disease and preexisting cardiovascular disease, AF remained significantly associated with excess mortality, with about a doubling of mortality in both sexes.ConclusionsIn subjects from the original cohort of the Framingham Heart Study, AF was associated with a 1.5- to 1.9-fold mortality risk after adjustment for the preexisting cardiovascular conditions with which AF was related. The decreased survival seen with AF was present in men and women and across a wide range of ages. (Circulation. 1998;98:946-952.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundUncontrolled studies have suggested that atrioventricular junction ablation and pacemaker implantation have beneficial effects on quality of life in patients with chronic atrial fibrillation (AF).90 bpm on 3 standard ECGs recorded at rest during stable clinical conditions on different days. Before completion of the study, withdrawals occurred in 8 patients of the drug group and in 4 patients of the Abl+Pm group. At the end of the 12 months, the 28 Abl+Pm patients who completed the study showed lower scores in palpitations (-78%; P=0.000) and effort dyspnea (-22%; P=0.05) than the 26 of the drug group. Lower scores, although not significant, were also observed for exercise intolerance (-20%), easy fatigue (-17%), chest discomfort (-50%), Living with Heart Failure Questionnaire (-14%), New York Heart Association functional classification (-4%), and Activity scale (-12%). The intrapatient comparison between enrollment and month 12 showed that in the Abl+Pm group, all variables except easy fatigue improved significantly from 14% to 82%. However, because an improvement was also observed in the drug group, the difference between the 2 groups was significant only for palpitations (P=0.000), effort dyspnea (P=0.01), exercise intolerance (P=0.005), easy fatigue (P=0.02), and chest discomfort (P=0.02). Cardiac performance, evaluated by means of standard echocardiogram and exercise test, did not differ significantly between the 2 groups and remained stable over time.ConclusionsIn patients with heart failure and chronic AF, Abl+Pm treatment is effective and superior to drug therapy in controlling symptoms, although its efficacy appears to be less than that observed in uncontrolled studies because some improvement can also be expected in medically treated patients. Cardiac performance is not modified by the treatment. (Circulation. 1998;98:953-960.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundRegional cardiac sympathetic hyperactivity predisposes to malignant arrhythmias in nondiabetic cardiac disease. Conversely, however, cardiac sympathetic denervation predicts increased morbidity and mortality in severe diabetic autonomic neuropathy (DAN). To unite these divergent observations, we propose that in diabetes regional cardiac denervation may elsewhere induce regional sympathetic hyperactivity, which may in turn act as a focus for chemical and electrical instability. Therefore, the aim of this study was to explore regional changes in sympathetic neuronal density and tone in diabetic patients with and without DAN.Methods and Results-PET using the sympathetic neurotransmitter analogue11C-labeled hydroxyephedrine ([(11) C]-HED) was used to characterize left ventricular sympathetic innervation in diabetic patients by assessing regional disturbances in myocardial tracer retention and washout. The subject groups comprised 10 diabetic subjects without DAN, 10 diabetic subjects with mild DAN, 9 diabetic subjects with severe DAN, and 10 healthy subjects. Abnormalities of cardiac [(11) C]-HED retention were detected in 40% of DAN-free diabetic subjects. In subjects with mild neuropathy, tracer defects were observed only in the distal inferior wall of the left ventricle, whereas with more severe neuropathy, defects extended to involve the distal and proximal anterolateral and inferior walls. Absolute [(11) C]-HED retention was found to be increased by 33% (P<0.01) in the proximal segments of the severe DAN subjects compared with the same regions in the DAN-free subjects (30%; P<0.01 greater than the proximal segments of the mild DAN subjects). Despite the increased tracer retention, no appreciable washout of tracer was observed in the proximal segments, consistent with normal regional tone but increased sympathetic innervation. Distally, [(11) C]-HED retention was decreased in severe DAN by 33% (P<0.01) compared with the DAN-free diabetic subjects (21%; P<0.05 lower than the distal segments of the mild DAN subjects).ConclusionsDiabetes may result in left ventricular sympathetic dysinnervation with proximal hyperinnervation complicating distal denervation. This combination could result in potentially life-threatening myocardial electrical instability and explain the enhanced cardioprotection from beta-blockade in these subjects. (Circulation. 1998;98:961-968.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundThe role of the L-type calcium channel in human heart failure is unclear, on the basis of previous whole-cell recordings.Methods and Results-We investigated the properties of L-type calcium channels in left ventricular myocytes isolated from nonfailing donor hearts (n=16 cells) or failing hearts of transplant recipients with dilated (n=9) or ischemic (n=7) cardiomyopathy. The single-channel recording technique was used (70 mmol/L Ba2+). Peak average currents were significantly enhanced in heart failure (38.2 +/- 9.3 fA) versus nonfailing control hearts (13.2 +/- 4.5 fA, P=0.02) because of an elevation of channel availability (55.9 +/- 6.7% versus 26.4 +/- 5.3%, P=0.001) and open probability within active sweeps (7.36 +/- 1.51% versus 3.18 +/- 1.33%, P=0.04). These differences closely resembled the effects of a cAMP-dependent stimulation with 8-Br-cAMP (n=11). Kinetic analysis of the slow gating shows that channels from failing hearts remain available for a longer time, suggesting a defect in the dephosphorylation. Indeed, the phosphatase inhibitor okadaic acid was unable to stimulate channel activity in myocytes from failing hearts (n=5). Expression of calcium channel subunits was measured by Northern blot analysis. Expression of alpha1C-and beta-subunits was unaltered. Whole-cell current measurements did not reveal an increase of current density in heart failure.ConclusionsIndividual L-type calcium channels are fundamentally affected in severe human heart failure. This is probably important for the impairment of cardiac excitation-contraction coupling. (Circulation. 1998;98:969-976.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundThe dynamic autonomic processes leading to vasovagal syncope are poorly understood.Methods and Results-We used complex demodulation to continuously assess changes in respiration, R-R interval, and arterial pressure (blood pressure) variability during 60 degree head-up tilt in 25 healthy subjects with tilt-induced vasovagal syncope and 25 age-matched nonsyncopal control subjects. Coherence and transfer function analyses were used to examine the relation between respiration and R-R interval variability before syncope. Baseline blood pressure, R-R, and ventilation were similar between syncope subjects and control subjects. Syncope subjects experienced an increase in tidal volume and decrease in BP beginning 3 minutes before impending syncope (systolic blood pressure <80 mm Hg) necessitated termination of tilt. Approximately 90 seconds before syncope there was a sudden prolongation of R-R interval and increase in amplitude of high and low frequency R-R interval variability, indicating an abrupt enhancement of vagal tone. The increase in respiratory amplitude between 180 and 90 seconds before syncope was not accompanied by changes in R-R interval or R-R variability, suggesting a dissociation between respiration and the respiratory sinus arrhythmia. The coherence analysis showed fewer syncope subjects with coherence between respiratory and R-R interval variabilities and lower transfer magnitudes in syncope subjects compared with control subjects. Nonsyncopal subjects had no change in respiratory, R-R interval, or blood pressure dynamics during matched time periods before the time of syncope.ConclusionsVasovagal syncope is preceded by a period of hyperpnea and cardiorespiratory decoupling followed by an abrupt increase in cardiovagal tone. Respiratory pumping without inspiratory cardiac slowing may partially counteract preload reduction until sudden bradycardia precipitates syncope. (Circulation. 1998;98:977-983.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundFor the detection of atherosclerotic lesions of the extracranial cerebral arteries, duplex ultrasonography (US) is an established operator-dependent method, whereas arteriography is associated with the not-insignificant risk of embolic complications. Spiral CT is a promising novel diagnostic tool that allows noninvasive, operator-independent diagnosis of obstruction of extracranial cerebral arteries. The aim of our prospective study was to evaluate in a clinical setting the complementary role of duplex US and spiral CT.Methods and Results-We compared the results obtained independently by spiral CT and duplex US in 59 consecutive patients with clinical suspicion of an obstructive lesion affecting the carotid arteries. We analyzed a total of 354 segments from the extracranial carotid arteries, including the common, internal, and external carotid arteries. A total of 4 complete occlusions, 38 severe stenoses (70% to 99%), and 32 moderate stenoses (30% to 69%) were concordantly identified by means of duplex US and spiral CT. In 5 cases in which duplex US did not allow sufficient evaluation of the carotid artery because of a poor US window or severe calcification, spiral CT allowed identification and correct measurement of the stenotic lesion. The comparison of the percentage of stenosis with both methods was good (r=0.91, P=0.024).ConclusionsOur results indicate that spiral CT of the extracranial cerebral arteries is a promising noninvasive complementary and non-operator-dependent examination. Its application is particularly attractive in cases in which duplex US is not reliable (ie, severe kinking, severe calcification, short neck, and high bifurcation) and particularly when an overall view of the vascular field is required. (Circulation. 1998;98:984-989.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundAlthough coronary artery lesions are critical complications of Kawasaki disease, their long-term outcome is still unclear. It is sometimes difficult to monitor progressive changes from aneurysms to stenotic lesions because coronary angiography (CAG) cannot be repeated very often, especially in infants. Our prospective study was designed to evaluate the prognostic value of dipyridamole-thallium single-photon-emission CT (SPECT) in the long-term follow-up of patients with Kawasaki disease.or=to8 years. During the follow-up interval, there were 15 cardiac events (1 death, 5 infarctions, 2 coronary artery bypass graft operations, and 7 occurrences of unstable angina). Of patients who had some event, thallium redistribution was found on SPECT in 14 (93%, P<0.001). Of the various clinical and scintigraphic image variables, the presence of thallium redistribution was the best multivariate independent predictor of a late cardiac event (chi squared=57.8, P<0.0001). The number of aneurysms detected on CAG added minimal statistical improvement to the model (chi squared=1.9, P=0.0009).ConclusionsDipyridamole-thallium SPECT is safely performed and is useful and important for risk stratification in the long-term follow-up of patients with Kawasaki disease. (Circulation. 1998;98:990-996.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundThe outcome of patients with corrected transposition of the great arteries (CTGA) is variably affected by associated intracardiac defects, tricuspid valve competence, and systemic right ventricular (RV) function. The relative importance of these factors in long-term outcome has not been evaluated.Methods and Results-Since 1958, 40 patients with CTGA were studied to determine risk factors for poor outcome, including age, open heart surgery, tricuspid insufficiency (TI), cardiac rhythm, pulmonary overcirculation, and RV dysfunction. Follow-up ranged from 7 to 36 years (mean 20 years). Intracardiac repair was performed in 21 patients; 19 were unoperated or had closed heart procedures. For the purposes of this study the designation TIsrefers to at least moderately severe TI as delineated by echocardiogram and/or angiography. TIswas the only independently significant factor for death (P=0.01), and in turn, only the presence of a morphologically abnormal TV predicted TIs(P=0.03). Twenty-year survival without TIswas 93%, but only 49% with TIs. Poor long-term postoperative outcome was due to TIsin all but 1 patient; 20-year survival rates for operated patients with and without TIswere 34% and 90%, respectively (P=0.002). Similarly, 20-year survival rates for unoperated patients with and without TIswere 60% and 100%, respectively, whether or not attempts to repair the TI were made (P=0.08).ConclusionsTIsrepresents the major risk factor for CTGA patients; RV dysfunction appears to be almost always secondary to long-standing TI. Decisions related to surgical interventions with or without associated lesions must be strongly influenced by the status of the tricuspid valve. (Circulation. 1998;98:997-1005.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID