ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—Minimally invasive coronary artery bypass (MIDCAB) is a new surgical technique by which the left internal mammary artery is anastomosed under direct visualization to the left anterior descending artery without cardiopulmonary bypass.Methods and Results—We followed all 274 patients who underwent MIDCAB from the time it was introduced at a single center. In-hospital and 1-year clinical events were source-documented and adjudicated. The in-hospital major acute cardiac event rate was 2.2%; this included a 1.1% mortality rate. At 1 year, the respective rates were 7.8% and 2.5%. When compared with the initial 100 procedures, the subsequent 174 procedures had shorter vessel occlusion times (10±5 versus 14±6 minutes;P=0.009), times to extubation (6±3 versus 14±10 hours;P<0.001), and lengths of hospital stay (2.1±1.9 versus 3.2±3.1 days;P=0.04). Cumulative 1-year adverse cardiac events were 11% in the initial 100 cases and 6% in the subsequent 174 cases (P=0.17).Conclusions—Excellent clinical results can be achieved with the MIDCAB technique. The clinical adverse event rate may decrease with accumulated experience.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—The basis for progressive attenuation of the effects of organic nitrates during long-term therapy (nitrate tolerance) remains controversial; proposed mechanisms include impaired nitrate bioconversion resulting in decreased release of nitric oxide (NO) from nitrates and/or increased NO clearance through a reaction with incrementally generated superoxide (O2–).Methods and Results—Patients undergoing elective coronary artery bypass were randomized to receive 24 hours of intravenously infused nitroglycerin (NTG; nitrate group) or no nitrate therapy (control group). Discarded segments of the internal mammary artery and saphenous vein were used to examine (1) vascular responsiveness to NTG, sodium nitroprusside, and the calcium ionophore A23187; (2) bioconversion of NTG to 1,2- and 1,3-glyceryl dinitrate; and (3) the generation of O2–. Responses to NTG were reduced 3- to 5-fold in vessels from the nitrate group compared with control vessels (P<0.01 for both types of segments), whereas responses to sodium nitroprusside and A23187 were unchanged. Tissue content of 1,2-glyceryl dinitrate was lower (P=0.012) in the saphenous veins from the nitrate group than in those from the control group. O2–generation was greater (P<0.01) in internal mammary artery samples from the nitrate group than in those from the control group. However, incremental O2–generation induced by an inhibitor of superoxide dismutase did not affect NTG responses.Conclusions—NTG tolerance in patients with coronary artery disease is nitrate-specific and is associated with evidence of impaired NTG bioconversion. Tolerance was associated with incremental O2–generation, but short-term elevation of O2–did not affect NTG responsiveness, suggesting increased NO clearance by O2–has a minimal contribution to tolerance.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—This study sought to assess whether novel markers of hemostatic activity are predictive of coronary heart disease (CHD) and improve risk assessment.Methods and Results—Conventional CHD risk factors, the activation peptides of factor IX and factor X, factor VII activity and antigen, activated factor XII, prothrombin fragment 1+2, fibrinopeptide A, and fibrinogen were measured in 1153 men aged 50 to 61 years who were free of myocardial infarction at recruitment. Activated factor VII (VIIa) was measured in 829 men. During 7.8 years of follow-up, 104 had a CHD event. Baseline status was related to outcome by logistic regression by using a modified nested case-control design. Screening performance was judged from receiver operating characteristic curves. A high activated factor XII was associated with increased CHD risk, but low levels were not protective. Plasma VIIa and factor X activation peptide were independently and inversely related to risk. Plasma factor IX activation peptide and fibrinogen were positively associated with risk, but the relations were no longer statistically significant after adjustment for other factors, including VIIa and apoA-I. Other hemostatic markers were not associated with CHD risk.Conclusions—Hemostatic status did not add significant predictive power to that provided by conventional CHD risk factors yet was able to substitute effectively for these factors.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—We investigated the applicability and image quality of contrast-enhanced coronary artery visualization by multislice spiral CT using retrospective ECG gating.Methods and Results—Twenty-five patients in sinus rhythm (significant coronary artery stenoses ruled out by invasive angiography) were studied with a multislice spiral CT (Siemens SOMATOM Volume Zoom). In inspiration (mean breathhold, 37 seconds), a volume data set of the heart was acquired (intravenous contrast agent; 4×1-mm slice thickness; 500-ms rotation; table feed, 1.5 mm/360°). Simultaneous recording of the ECG permitted retrospective reconstruction of contiguous cross sections in intervals of 1 mm at any desired interval of the cardiac cycle. The mean duration of the image reconstruction window was 185 ms. Next to 3-dimensional reconstructions of the heart and coronary arteries, multiplanar reconstructions were rendered to determine the visualized length of the coronary arteries, the contrast-to-noise ratio, and the correlation of coronary artery diameters to quantitative coronary angiography.Conclusions—The coronary arteries could be visualized over long segments (left main, 9±4 mm; left anterior descending, 112±34 mm; left circumflex, 80±29 mm; right coronary artery, 116±33 mm). On average, 78±16% of these distances were visualized free of motion artifacts. The mean contrast-to-noise ratio was 9.3±3.3. Coronary artery diameters in multislice spiral CT showed close correlation to quantitative coronary angiography (CT, 3.3±1.0 mm; angiography, 3.2±0.9 mm; mean difference, 0.38 mm;r=0.86). Contrast-enhanced multislice spiral CT permits visualization of the coronary artery lumen. Further studies are necessary to determine whether image quality is sufficient to reliably detect coronary artery stenoses.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—Clinical manifestations of acute myocarditis, with distinct onset, vary from asymptomatic to fatal. The predictors of the course of the disease in patients with acute myocarditis at initial presentation have not yet been established. In this study, we examined the predictive values of various parameters in the disease course of patients with myocarditis.Methods and Results—Twenty-one consecutive patients who had been diagnosed as having acute myocarditis by histological examinations were analyzed. The patients with myocarditis were divided into the survival group (n=13) and the fatal group (n=8). We examined the parameters of the clinical state, hemodynamic variables, required therapies, biochemical laboratory data, and cytokines. The control groups were composed of 23 patients with old myocardial infarction and 20 healthy volunteers. The fatal group had lower blood pressure and higher pulmonary capillary wedge pressure compared with those values in the survival group. Mechanical ventilation support was more frequently required in the fatal group. Serum levels of soluble Fas (sFas) and soluble Fas ligand (sFasL) were significantly higher in the myocarditis group than in the 2 control groups. Furthermore, levels were significantly higher in the fatal group than in the survival group for sFas (13.93±4.77 versus 3.77±0.52 ng/mL, respectively;P<0.001) and sFasL (611.4±127.7 versus 269.5±37.3 pg/mL, respectively;P<0.05). Other clinical states, hemodynamic variables, required therapies, and biochemical laboratory parameters were not different between the 2 groups.Conclusions—Elevation of sFas and sFasL levels at initial presentation appear to be a good serological marker to predict the prognosis of acute myocarditis.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—Serotonergic medications with various mechanisms of action are used to treat psychiatric disorders and are being investigated as treatments for drug dependence. The occurrence of fenfluramine-associated valvular heart disease (VHD) has raised concerns that other serotonergic medications might also increase the risk of developing VHD. We hypothesized that fenfluramine or its metabolite norfenfluramine and other medications known to produce VHD have preferentially high affinities for a particular serotonin receptor subtype capable of stimulating mitogenesis.Methods and Results—Medications known or suspected to cause VHD (positive controls) and medications not associated with VHD (negative controls) were screened for activity at 11 cloned serotonin receptor subtypes by use of ligand-binding methods and functional assays. The positive control drugs were (±)-fenfluramine; (+)-fenfluramine; (−)-fenfluramine; its metabolites (±)-norfenfluramine, (+)-norfenfluramine, and (−)-norfenfluramine; ergotamine; and methysergide and its metabolite methylergonovine. The negative control drugs were phentermine, fluoxetine, its metabolite norfluoxetine, and trazodone and its active metabolitem-chlorophenylpiperazine. (±)-, (+)-, and (−)-Norfenfluramine, ergotamine, and methylergonovine all had preferentially high affinities for the cloned human serotonin 5-HT2Breceptor and were partial to full agonists at the 5-HT2Breceptor.Conclusions—Our data imply that activation of 5-HT2Breceptors is necessary to produce VHD and that serotonergic medications that do not activate 5-HT2Breceptors are unlikely to produce VHD. We suggest that all clinically available medications with serotonergic activity and their active metabolites be screened for agonist activity at 5-HT2Breceptors and that clinicians should consider suspending their use of medications with significant activity at 5-HT2Breceptors.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—Congenital long-QT syndrome (LQTS) is caused by mutations of genes encoding the slow component of the delayed rectifier current (LQT1, LQT5), the rapid component of the delayed rectifier current (LQT2, LQT6), or the Na+current (LQT3), resulting in ST-T–wave abnormalities on the ECG. This study evaluated the spectrum of ST-T–wave patterns and repolarization parameters by genotype and determined whether genotype could be identified by ECG.Methods and Results—ECGs of 284 gene carriers were studied to determine ST-T–wave patterns, and repolarization parameters were quantified. Genotypes were identified by individual ECG versus family-grouped ECG analysis in separate studies using ECGs of 146 gene carriers from 29 families and 233 members of 127 families undergoing molecular genotyping, respectively. Ten typical ST-T patterns (4 LQT1, 4 LQT2, and 2 LQT3) were present in 88% of LQT1 and LQT2 carriers and in 65% of LQT3 carriers. Repolarization parameters also differed by genotype. A combination of quantified repolarization parameters identified genotype with sensitivity/specificity of 85%/70% for LQT1, 83%/94% for LQT2, and 47%/63% for LQT3. Typical patterns in family-grouped ECGs best identified the genotype, being correct in 56 of 56 (21 LQT1, 33 LQT2, and 2 LQT3) families with mutation results.Conclusions—Typical ST-T–wave patterns are present in the majority of genotyped LQTS patients and can be used to identify LQT1, LQT2, and possibly LQT3 genotypes. Family-grouped ECG analysis improves genotype identification accuracy. This approach can simplify genetic screening by targeting the gene for initial study. The multiple ST-T patterns in each genotype raise questions regarding the pathophysiology and regulation of repolarization in LQTS.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Background—We report the first successful slow pathway ablation using a novel catheter-based cryothermal technology for the elimination of atrioventricular nodal reentrant tachycardia (AVNRT).Methods and Results—Eighteen patients with typical AVNRT underwent cryoablation. Reversible loss of slow pathway (SP) conduction during cryothermy (ice mapping) was demonstrated in 11 of 12 patients. Because of time constraints, only 2 sites were ice mapped in 1 patient. Seventeen of 18 patients had successful cryoablation of the SP. One patient had successful ice mapping of the SP, but inability to cool beyond −38°C prevented successful cryoablation. A single radiofrequency lesion at this site eliminated SP conduction. No patient has had recurrent AVNRT over 4.9±1.7 months of follow-up. During cryoablation, accelerated junctional tachycardia was not seen and was therefore not available to guide lesion delivery. Adherence of the catheter tip during cryothermy (cryoadherence) allowed atrial pacing to test for SP conduction. Cryoablation in the anterior septum produced inadvertent transient PR prolongation consistent with loss of fast pathway conduction in 1 patient and transient (6.5 seconds) 2:1 AV block in another. On rewarming, the PR interval returned to normal, and the AV nodal effective refractory period was unchanged in both. Accelerated junctional tachycardia was seen on rewarming in both but not during cryothermy.Conclusions—Cryothermal ablation of the SP was achieved in patients with this novel technique. Successful ice mapping of both the SP and fast pathway was demonstrated. The ability to test the functionality of specific ablation sites before production of a permanent lesion may eliminate inadvertent AV block.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundThe matrix-degrading activity of matrix metalloproteinases (MMPs), required for cell migration and general tissue reshaping, is thought essential for pathological arterial remodeling in atherosclerosis and restenosis.Methods and ResultsWe triggered remodeling of the carotid artery in C57BL/6 mice by blood flow cessation to study the relationship with gelatinases MMP-9 and MMP-2. Ligated and contralateral carotid arteries from ligated and sham-operated mice were harvested fresh, for biochemical analyses, or were perfusion-fixed, for histological studies, at 0, 1, 3, 7, 14, and 28 days after ligation. An early statistically significant (P<0.01) 4- to 5-fold increase in MMP-9 expression detected by SDS-PAGE zymography and Western blotting in tissue homogenates of ligated carotid arteries 1 day after flow cessation was maintained through day 7, after which expression gradually fell. Maximal MMP-9 levels were higher than MMP-2 levels, which became significantly increased 7 days after ligation. Proliferating cells, identified by bromodeoxyuridine incorporation, were detectable at day 1 in the adventitia and subsequently throughout the wall. Neointima was visible in 3-day specimens of ligated arteries. Suggested by morphology and predicted by theoretical considerations, maximal MMP-9 expression coincided with cell migration into the neointima, supporting its enabling role. Morphological measurements also demonstrated positive lumen remodeling up to 7 days after ligation.ConclusionsMMP-9 induction is associated with the formation of intimal hyperplasia and does not require frank mechanical injury. Our data also show that a significant increase in MMP-9 expression preceded the positive geometrical remodeling of arteries, suggesting a potentially beneficial role for this matrix-degrading enzyme.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID