慢性心房颤动患者心室率变化意义的探讨

目的分析探讨慢性心房颤动患者心室率变化的意义，为临如何预防心房颤动患者出现脑栓塞、心功能降低等并发症提供理论依据。方法将入院或门诊就诊病程超过1年的慢性心房颤动患者分为脑栓塞组和非脑栓塞组，各30例，观察比较两组患者临床特征，动态心电图计数比较两组患者最大心室率、平均心室率及最小心室率变化，超声心动图测定两组患者左房内径大小、左室射血分数变化，血浆凝血酶原时间凝固法测定两组患者血浆凝血酶原时间国际标准化比值（INR）变化。结果两组患者一般临床特征、左房内径大小、INR值比较。差异无统计学意义。脑栓塞组最大心室率、平均心室率及最小心室率均明显快于非脑栓塞组，左室射血分数明显低于非脑栓塞组。结论慢性心房颤动患者降低心室率对预防脑栓塞、左心功能降低有重要意义。     

Mental stress-induced myocardial ischemia in coronary artery disease patients with left ventricular dysfunction

Background  Reduced left ventricular ejection fraction (LVEF) is a risk factor for poor outcomes in patients with coronary artery disease (CAD). Mental stress-induced myocardial ischemia (MSIMI) also identifies a subset of CAD patients at increased risk for future cardiovascular events. Susceptibility to MSIMI in patients with CAD and reduced LVEF is unknown. Methods and Results  We enrolled 182 patients (67 women) with a mean age of 64 years and a documented history of CAD in this study. Baseline resting ejection fraction was determined by use of technetium 99m sestamibi gated single photon emission computed tomography. Abnormal LVEF was defined as less than 45% for men and less than 50% for women (based on published norms for our software [Cedars-Sinai Medical Center]). All participants underwent mental stress testing with a public speaking task. Rest/stress myocardial perfusion single photon emission computed tomography was performed via conventional methodology. Images were visually compared for number and severity of perfusion defects by use of a scoring method from 0 to 4. A summed difference score was calculated as the difference between summed stress and rest scores. A score of greater than 3 was considered abnormal. MSIMI developed in 19% of patients with normal LVEF and 31% of those with reduced LVEF. There is no statistically significant difference between the two groups (P=.11). Conclusions  CAD patients with left ventricular dysfunction are equally susceptible to MSIMI as those with normal LVEF. This study was supported by grants HL 070265 and HL 072059 from the National Heart. Lung, and Blood Institute. This material is also the result of work supported by resources and with the use of facilities at the Department of Veterans. Affairs Medical Center, Gainesville, Fla.     

Body mass index, percent body fat, and bone mass in a cohort of Chinese twins aged 6 to 18 years

Introduction This report examines the relationship of body mass index (BMI), percent body fat (%BF), and bone mass in a cohort of male and female twins recruited from Anhui province, China, ages 6–18 years—577 male pairs (mean age = 11.4) and 478 female pairs (mean age = 11.6). Methods Whole body bone mineral content (WBMC) in (g), whole body bone area (WBA) in (cm²), and %BF were measured using DEXA (Lunar Prodigy, USA). Regression analysis of within-pair differences was used to assess the strength of the association, and the analysis was stratified by gender and age group, where age cut-offs were based on ages at spermarche or menarche estimated from large population based studies in China. Males were stratified at ages before 14 and age 14–18, and females at ages prior to 12 and age 12–18. Results Univariately, BMI and %BF were associated with WBMC and WBA in the younger males and females, and in older males; %BF was significant only in older females. Multivariate models included both BMI and %BF. Among the younger males, age < 14, BMI and %BF were significantly associated with WBMC and WBA. In the younger females, age < 12, %BF was only significant to WBA. In the older age group, only BMI was significant to WBMC and WBA in females, but in males, BMI was positively associated, and %BF was negatively associated with both bone measures. Discussion These findings show that association between BMI and %BF and bone mass differ across gender and developmental stages, and %BF appears to be beneficial at younger ages, but detrimental or non-beneficial at older ages of development.     

中国围绝经期妇女体脂含量与骨密度关系的初步研究

目的探讨肌肉、脂肪含量与围绝经期骨质疏松妇女骨密度之间的关系。方法利用双能X线骨密度测量仪(美国,Hologic DiscoveryA型)测量门诊围绝经期妇女(90例,年龄:45~52岁(47.3±8.2))骨密度与体脂含量;同时测量登记受试者的年龄、身高、体重。结果结果显示,21%受试者腰椎和股骨骨量降低,全身脂肪含量(20675.129±5080.44)g与腰椎骨密度(0.91±0.177)g/cm2(P>0.05,r=-0.17)和髋部骨密度(0.99±0.102)g/cm2(P>0.05,r=0.158)没有相关性,肌肉含量(39790.80±6551.54)g与腰椎骨密度没有相关性(P>0.05,r=0.078),但是与髋部骨密度高度正相关(P<0.05,r=0.216)。体重(63.01±9.39)kg和腰椎(P<0.05,r=0.217)和髋部(P<0.05,r=0.305)骨密度高度正相关;BMI指数(24.6751±3.45637)与腰椎(P<0.05,r=0.244)和髋部(P<0.01,r=0.339)骨密度高度正相关。结论研究结果表明BMI指数和肌肉含量与围绝经期妇女髋部骨密度高度相关。     

主动脉内球囊反搏在低射血分数患者非体外循环冠状动脉旁路移植术中应用的必要性探讨

目的探讨对低射血分数患者施行非体外循环冠状动脉旁路移植术(off-pump coronary artery bypass grafting, OPCAB)预防性应用主动脉内球囊反搏(intraaortic balloon pump, IABP)辅助的必要性. 方法 2001 年1 月～2004年10月对64例低射血分数(LVEF≤40%)施行OPCAB,将64例分为2组:术前或术中预防性应用IABP辅助者列为IABP组,共19例;未应用IABP者列为对照组,共45例. 结果 IABP组与对照组在术后并发症手术死亡、脑血管意外、肾功能衰竭衰血滤、围手术期心肌梗死等方面无显著差异(χ2=0.000,P=1.000).IABP组术后需要延长呼吸机带机时间(超过24 h)的比例显著高于对照组(IABP组8例,对照组3例; χ2=9.429,P=0.002);IABP组术后监护时间延长(超过48 h)的比例显著高于对照组(IABP组14例,对照组19例; χ2=4.110,P=0.043). 结论在无IABP辅助的情况下,为低射血分数患者实施OPCAB手术是可行的.     

Mortality risk associated with ejection fraction differs across resting nuclear perfusion findings

Background  Left ventricular ejection fraction (LVEF) is a significant predictor of morbidity and death. The nuclear summed rest score (SRS) measures myocardial perfusion defects and provides prognostic information, but its effects on long-term outcomes are not fully established. Moreover, information regarding the potential interaction between these 2 covariates is limited. The purpose of this study was to determine whether the mortality risk associated with LVEF is the same across all values of SRS in a population undergoing evaluation for ischemic heart disease. Methods and Results  We examined 3,187 patients who underwent cardiac catheterization and perfusion single photon emission computed tomography imaging with a maximum follow-up of 8.1 years and median follow-up of 3.1 years. Cox proportional hazards modeling showed that increasing nuclear SRS and decreasing LVEF were independently associated with a higher long-term mortality rate, with a clinically significant interaction between them (P=.032). Patients with a normal LVEF and a high SRS (greater perfusion abnormality) have a prognosis similar to those with a reduced LVEF. Conclusions  Resting perfusion studies provide prognostic information for long-term survival and significantly impact the interpretition of mortality risk associated with changes in LVEF. Patient prognostication, risk stratification, and future research using these variables should take this interaction into account. Supported by a grant from the Tom & Lynn Royster Foundation. Durham, NC, and a National Institutes of Health Research Fellowship Grant (T5 GM08679-04), Bethesda, Md.     

Bone marrow fat content in relation to bone remodeling and serum chemistry in intact and ovariectomized dogs

Summary It was previously shown that 11 months after ovariectomy the volume fraction of trabecular bone in the spine and 11th rib medullary canal of Beagle dogs (6 control, 9 ovariectomized) was significantly reduced. In this paper it is shown that these changes are accompanied by increased marrow fat volume in the 11th rib (59.0±9.5% vs. 44.3 ±10.0%). Conversely, the volume fraction of functional (hematopoietic) cells in the marrow was reduced by ovariectomy. Additionally, variations in marrow fat volume were tested for correlation with 22 other variables pertinent to bone physiology. Marrow fat volume was significantly positively correlated with serum osteocalcin, rib trabecular bone porosity, rib cross-sectional area, and gains in body weight. It was negatively correlated with serum estrogen concentrations and the extent of rib trabecular surfaces labeled with tetracycline.     

Ejection fraction by combined inverse Fourier analysis and second-derivative technique: Correlation with isocontour method

Summary In order to measure ejection fractions (EFs) from nuclear ventriculograms, we devised a semi-automated edge-detection technique based on a combination of inverse Fourier analysis and second-derivative techniques. Initial clinical studies showed that, for the left ventricle, our method gives EF values statistically identical with those obtained using a conventional isocontour technique. For the right ventricle, however, the values obtained using the two methods were somewhat more at variance. Despite requiring a longer processing time, the results obtained with our method are reproducible because less operator intervention is necessary.     

肝脏外科患者术后输注脂肪乳剂对蛋白质代谢的影响

将32例肝脏外科疾病患者随机分为Ⅰ组（单能源TPN组10例）；Ⅱ组（双能源TPN组11例，其中脂肪乳剂用量为1g·kg－1·d－1）；Ⅲ组（双能，TPN组11例，其中脂肪乳剂用量为2g·kg－1·d－1）。术后按组别给予TPN支持共6天，术前1天、术后第1和第6天测定肝功，糖代谢及蛋白质合成代谢指标。结果：①Ⅱ、Ⅲ组术后第6天肝脏酶学指标明显下降（P＜0．05），而Ⅰ组仍高于术前水平（P＜O．05）；②Ⅱ、Ⅲ组术后糖代谢基本恢复正常，而Ⅰ组出现高血糖症及高胰岛素血症（P＜0．05）；③Ⅱ组肝脏蛋白质合成水平恢复术前水平或略有提高（P＜0．05），而Ⅰ和Ⅲ组术后蛋白质合成功能仍低（P＜0．05）。结果提示：含脂肪乳剂的TPN支持对肝脏外科患者术后的肝功恢复有益，能促进蛋白质合成及肝细胞再生，并且在进行TPN支持时按1g·kg－1·d－1给予脂肪乳剂较为安全合理。     

The estimation of the plasma free fraction of cyclosporine in rabbits and heart transplant patients: The application of a physiological model of renal clearance

We estimated the free fraction (f_u) of cyclosporine (CyA) in the plasma from concentrations of CyA in urine (C_u) and plasma (C_p), urine flow rate (UF), and glomerular filtration rate in rabbits and in heart transplant patients. Following intravenous administration of CyA (5–30 mg kg^?1) in ten NZW rabbits and oral administration of CyA (4.8–12.1 mg kg^?1) in nine heart transplant patients, CyA concentrations in urine and plasma were measured by HPLC. The ratios of C_u to C_p and UF data were fitted to a physiological model of renal clearance using NONMEM. The free fraction of cyclosporine in the rabbits and the heart transplant patients was 0.0122 and 0.14, respectively. Because of the relatively low permeability of CyA across the tubular epithelium, no apparent equilibrium between C_u and C_p at any urine flow rate was reached and, therefore, the C_u to C_p ratio will not be equal to f_u.