老年冠心病患者的动态心电图观察

对97例老年冠心病患者进行动态心电图观察,共检出97例患者缺血性ST段发作347阵,心率减慢时发生缺血48例(49.5％),全程无症状者75例(77.4%),缺血时有无胸痛与ST段下降程度无必然联系。     

Reperfused myocardial infarctions on T1- and susceptibility-enhanced MRI: Evidence for loss of compartmentalization of contrast media

The purpose of this study was to characterize the contrast caused by a susceptibility MRI contrast agents, on spin echo T₂-weighted imaging of reperfused myocardial infarction. Our interest in this model focused on the expected requirement that such agents be compartmentalized in the tissue to cause signal loss on spin echo images, a condition which may not be present in reperfused infarcted myocardium. Accordingly, nine rats were subjected to 2 h of left coronary artery occlusion followed by 3 ± 0.5 h of reperfusion prior to administration of contrast media. Three sets of MR images were acquired: (a) baseline axial images at the midventricle, both T₁-weighted (TR/TE = 300/20) and T₂-weighted (TR/TE = 1500/60); (b) T₁-weighted images after administering a T₁-enhancing agent, Gd-DTPA-BMA (0.2 mmol/kg), to document that contrast media is delivered to the reperfused infarction; and (c) T₂-weighted images after administering the susceptibility agent, Dy-DTPA-BMA (1.0 mmol/kg). Gadolinium-enhanced T₁ images depicted reperfused infarction as regions with greatly enhanced signal intensity compared with unin-farcted myocardium, indicating that contrast agent was delivered to the infarcted zone. Dysprosium-enhanced T₁ images depicted the injury as a region of persistent signal intensity relative to depletion of signal in normal myocardium, consistent with failure of the contrast agent to cause signal loss. Similar infarction sizes were observed for unenhanced T₂-weighted images (33 ± 5%), gadolinium-enhanced T₁ weighted images (36 ± 5%) and postmortem staining (30 ± 6%); strong correlations (r > 0.9) were noted in comparisons of these data. Dysprosium-enhanced images exhibited a smaller region of differential signal presumed to be infarction (20 ± 5%, P < 0.05) and weak correlations (r < 0.75) with the other measurements. We conclude that the smaller infarction depicted on dysprosium-enhanced images is a subregion of the true infarction in which myocardial necrosis is sufficiently advanced that the agent is homogeneously distributed throughout all tissue compartments, preventing T₂*-dependent phase loss on spin echo images.     

三七皂甙对心肌腺苷三磷酸酶的影响(英文)

三七总皂甙(PNS)能抑制心肌总ATP酶活力,但对Na~( )-K~( )-ATP酶无明显影响。三七皂甙单体Rb_1及Rg_1对心肌总ATP酶活力均有抑制作用,但Rb_1的抑制效力显著大于Rg_1·Rb_1能抑制豚鼠离体心房肌的自律性和收缩性,Rg_1也能抑制豚鼠离体心房肌的自律性,但对心房肌的收缩性却无明显影响。提示PNS抑制心肌收缩力这一作用的主要有效成份是Rb_1·     

~(99m)Tc-MIBI心肌灌注显像结合门电路心血池显像对高血压患者心肌缺血诊断的评价

本文对40例住院高血压患者作了静息相及负荷相99mTc－MIBI心肌单光子发射计算机断层（SPECT）显像并采用门电路心血池显像（MGBP）评价室壁运动。结果显示：本组病例心肌灌注显像放射性稀疏缺损（MPD）发生率高达87．5％（35／40），其中可逆性（RPD）57．1％；有MPD者在MPD节段室壁运动异常发生率91．4％（32／35），但RPD组与非RPD组间无显著差异。文中对高血压患者心肌缺血及其导致MPD的机制进行了探讨，认为99mTc－MIBI心肌SPECT显像出现MPD是反映高血压患者心肌缺血的敏感方法，MGBP多指标评价室壁运动可揭示绝大多数MPD节段的室壁运动异常。     

Phase-sensitive cardiac tagging--REALTAG.

Fully inverting spins, instead of merely saturating them, provides superior contrast for tagging procedures. The resulting improvement in tag contrast-to-noise ratio (CNR) yields higher-precision tag detection. Also, thinner slices and hence reduced tag separations can be employed, providing displacement and strain measurements with better spatial resolution. Alternatively, the improved tag contrast can be used to obtain cine images covering a greater portion of the cardiac cycle. The use of standard magnitude reconstruction for images of these inversion tags causes rectification of the negative-valued signals from the tags, confounding the image interpretation. Therefore, a phase-sensitive reconstruction scheme of the inverted tags must be employed. Here we demonstrate the implementation of inverted tags with phase-sensitive reconstruction in a ramped-flip-angle, steady-state free precession (SSFP) sequence.     

A Bayesian iterative transmission gradient reconstruction algorithm for cardiac SPECT attenuation correction

Background  High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data. Methods and Results  The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients (mean SD, 0.005 cm⁻¹ vs 0.011 cm⁻¹; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP. Conclusion  This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum of patient BMI values and significantly improves attenuation-corrected perfusion images.     

Three-dimensional magnetic resonance myocardial motion tracking from a single image plane.

Three-dimensional imaging for the quantification of myocardial motion is a key step in the evaluation of cardiac disease. A tagged magnetic resonance imaging method that automatically tracks myocardial displacement in three dimensions is presented. Unlike other techniques, this method tracks both in-plane and through-plane motion from a single image plane without affecting the duration of image acquisition. A small z-encoding gradient is subsequently added to the refocusing lobe of the slice-selection gradient pulse in a slice following CSPAMM acquisition. An opposite polarity z-encoding gradient is added to the orthogonal tag direction. The additional z-gradients encode the instantaneous through plane position of the slice. The vertical and horizontal tags are used to resolve in-plane motion, while the added z-gradients is used to resolve through-plane motion. Postprocessing automatically decodes the acquired data and tracks the three-dimensional displacement of every material point within the image plane for each cine frame. Experiments include both a phantom and in vivo human validation. These studies demonstrate that the simultaneous extraction of both in-plane and through-plane displacements and pathlines from tagged images is achievable. This capability should open up new avenues for the automatic quantification of cardiac motion and strain for scientific and clinical purposes.     

纤溶酶原激活剂抑制物-1及其基因多态性与急性心肌梗死的相关性研究

目的：研究纤溶酶原激活剂抑制物－1（PAI－1）活性及其等位基因多态性与急性心肌梗死（AMI）之间的关系，从基因水平揭示AMI发病的危险因素。方法：AMI组55例、对照组48例健康者分别应用特异性寡核苷酸点膜杂交技术，进行PAI－1启动子区4G／5G多态性分析，用发色底物法测定血浆PAI－1活性。结果：AMI组和对照组中4G／4G基因型的血浆PAI－1活性水平最高，与4G／5G基因型、5G／5G基因型比较有显著性差异（P＜0．01）。AMI组中4G／4G纯合子基因型频率明显高于对照组（P＜0．05）。结论：血浆PAI－1活性增高是AMI发病的危险因素之一，4G／4G纯合子基因型是AMI发病的危险基因型。     

老年急性心肌梗塞病人PTF_(v1)的分析

本文分析91例60岁以上急性心肌梗塞(AMI)病人的心电图 V_1导联上 P 波的终末电势(PTFv_1)由 V_1导联的负向 P 波深度×宽度求得,单位为 mm·s。正常值≥-0.03mm·s,本组 PTFv_1异常者共44例,占48.4%,与 AMI 病人的年龄、梗塞部位、面积扩大及泵衰竭的增重有很大关系。经过治疗,随着病情的好转 PTFv_1可恢复正常。因此,PTFv_1对老年 AMI 的预后判断具有很大的意义。     

Felodipine or Hydrochlorothiazide/Triamterene for Treatment of Hypertension in the Elderly: Effects on Blood Pressure, Hypertensive Heart Disease, Metabolic and Hormonal Parameters

Trenkwalder P, Plaschke M, Aulehner R, Lydtin H. Felodipine or Hydrochlorothiazide/Triamterene for Treatment of' Hypertension in the Elderly: Effects on Blood Pressure, Hypertensive Heart Disease, Metabolic and Hormonal Parameters.

The aim of the study was to compare the antihypertensive efficacy of either felodipine or the diuretic combination hydrochlorothiazide/triamterene in a group (n = 65) of elderly (≥70 years) hypertensives (office blood pressure ≥ 60/95 mmHg) with special regard to ambulatory blood pressure monitoring, hypertensive heart disease and metabolic parameters. This was a randomized, double-blind study with a treatment period of 6 months. Reduction of office and 24-hr ambulatory blood pressure was comparable with both treatment regimens; after 6 months, 18 of 29 patients in the felodipine group (62%) and 20 of 27 patients in the diuretic group (74%; p = 0.4) were controlled. While episodes of ischemic type ST-segment depression were significantly reduced in the felodipine group (from 49 to 9 episodes), there was no significant change in the diuretic group (from 24 to 21 episodes). Both regimens decreased left ventricular wall thickness, but the decline in left ventricular muscle mass index was significant only for felodipine. Felodipine did not induce any change in metabolic or hormonal parameters; the diuretic combination significantly increased serum creatinine, uric acid, plasma renin activity, and plasma prorenin. Thus, the antihypertensive efficacy of felodipine and the diuretic combination was comparable in elderly hypertensives; only felodipine, however, improved parameters of hypertensive heart diesease and showed a neutral metabolic and hormonal profile.