Ⅱ型糖尿病患者无症状性心肌缺血及其相关因素分析

目的 了解Ⅱ型糖尿病(T2DM)患者无症状性心肌缺血(SMI)的发病情况,探讨与其相关的主要危险因素.方法 217例无心绞痛(或与心绞痛等同症状)的T2DM患者,根据心电图(静息、动态或负荷试验)诊断有无心肌缺血分为两组,对比观察心肌缺血与临床一股情况及各生化指标的相关性.结果 T2DM患者SMI发病率20.7%,其中女性与男性之比为3∶2,SMI组中年龄、血压、BMI、2hPG、HbAlc、TG、TC、LDL-C均高于时照组,而HDL-C低于对照组,且SMI组中吸烟者所占比例亦高于对照组.结论 T2DM患者中多种危险因子的集簇增加了心血管病变发生的机率,且女性患者心肌缺血的比例超过男性,提示对女性T2DM患者加强控制心血管危险因子的干预甚至比男性更重要.     

Silent myocardial ischemia

ST-segment depression in the absence of symptoms is now a well-defined abnormality in patients with coronary artery disease. ST-segment depression without the occurrence of angina is a marker for myocardial perfusion defects and ischemia. During 24-hour recordings, most episodes of ischemia in patients with coronary artery disease are silent and occur with relatively normal heart rates. The combination of silent ischemia and ischemia associated with angina is referred to as total ischemic burden. Silent ischemia is prognostically important for identifying patients in whom subsequent myocardial events may develop. The episodes of silent ischemia, and thus total ischemic burden, can be reduced by standard antianginal therapy, a measure that may have a favorable influence on patient outcome. Proof that reduction of the total ischemic burden actually improves outcome, however, is not yet available.     

Silent myocardial ischemia: improvement with nisoldipine therapy

Nisoldipine is a new calcium channel blocker of the dihydropyridine family with a high affinity for coronary vessels. We assessed the efficacy of nisoldipine in the treatment of asymptomatic ischemia in 12 patients with chronic, stable angina. Two to four weeks of daily therapy with prn nitroglycerin and placebo was followed by 24-hour ambulatory electrocardiographic recording for ST segment assessment. After two weeks of once-daily nisoldipine, 10 to 20 mg, the ambulatory recording was repeated. A significant difference was seen in ischemia-magnitude products of asymptomatic ischemic episodes in placebo versus active drug periods (P less than .05). When total ischemic burden was considered (ST segment depression during both painless and painful episodes), the difference was even more significant (P less than .02).     

Silent myocardial ischemia. Answers to frequently asked questions

Patients with coronary artery disease and silent myocardial ischemia have a prognosis similar to that of symptomatic patients. Screening of totally asymptomatic patients is not likely to identify many with silent ischemia. However, certain cohorts of patients--middle-aged men with two or more risk factors for coronary arteriosclerosis--are at risk of presenting initially with myocardial infarction or sudden death, and the screening of such persons is advised. Use of radionuclear imaging techniques during exercise stress testing appears to be helpful in identifying patients at high risk, who should then be offered coronary arteriography. An ideal treatment has not been established, but a treatment strategy based on symptom relief alone is suboptimal. Measures used for symptomatic ischemia are just as effective with silent ischemia. Treatment must be individualized, and ambulatory electrocardiographic monitoring appears useful in adjusting antiischemic therapy for a given patient.     

Silent myocardial ischemia: an update

Silent myocardial ischemia is diagnosed by several different techniques and has been documented in all the anginal syndromes. In addition to other factors, its presence may be related to increased pain threshold and increased pain tolerance. Although some patients with painless ischemia may have less extensive coronary artery disease, cumulative evidence indicates that silent myocardial ischemia does not necessarily signify a lesser degree of cardiac ischemia or a less severe coronary abnormality. As judged by ambulatory monitoring studies, it shows circadian variation; occurs more frequently than symptomatic ischemia; and appears to depend, in large part, on activation of the sympathetic nervous system. Frequent silent ischemic events during ambulatory monitoring are worrisome because they reflect the disease "activity" of single or multiple coronary atherosclerotic lesions. Thus, there may be a direct association between the severity of ischemia seen during Holter monitoring, the extent of underlying coronary artery disease or disease activity, and prognosis. When diagnosed by exercise testing, silent myocardial ischemia may be associated with significant coronary involvement. In this regard, patients with three vessel coronary disease, impaired left ventricular function, and silent ischemia during stress testing should benefit from coronary revascularization. Compared with symptomatic patients, other evidence suggests that patients with exercise-induced asymptomatic ischemia have at least the same or perhaps even a worse outlook; this may be related to the lack of symptoms that would prompt evaluation and therapy. Awareness of the possibility of silent myocardial ischemia and use of commonly available tests, both to establish its presence and severity and to guide treatment, are emerging as new clinical goals. Further data, however, are necessary to determine how vigorously this should be pursued in different patient subgroups. In association with unstable angina or post-myocardial infarction, the added risk of silent myocardial ischemia warrants a more aggressive approach.     

Silent myocardial ischemia is associated with altered plasma phospholipids

Timely and accurate confirmation of the occurrence of silent myocardial ischemia (SMI) is critical both for prevention and therapy management. Metabolomics assay may offer an alternative for SMI differentiation and altered biomolecule discovery in addition to traditional measures. In this study, plasma samples were obtained from 14 diagnosed SMI subjects and 25 healthy controls and analyzed by liquid chromatography coupled with quadrupole‐time‐of‐flight mass spectrometry in view of metabolomics. Obtained data were subjected to orthogonal signal correction partialleast‐squares discriminate analysis. Multi‐variate statistic analysis indicated a clear separation between the two studied groups. Plasma concentration fluctuation of four kinds of phospholipids showed tight relationship with the occurrence of SMI, among which 1‐linoleoylglycerophosphocholine (C18:2) was decreased statistically in SMI population (P=0.01). The plasma phospholipids' changes were before enzymatic alteration in SMI, which might be a useful complementary reference to facilitate SMI diagnosis. J. Clin. Lab. Anal. 23:45–50, 2009. © 2009 Wiley‐Liss, Inc.     

Silent myocardial ischemia during rehabilitation for cerebrovascular disease

In asymptomatic patients the importance of silent ischemic ST-T wave changes on Holter monitoring is known to be a significant predictive variable for one-year mortality of postmyocardial infarction patients. This case report represents the uses of ambulatory ECG to detect ischemic ST changes in patients who have had recent strokes. The cases reported here of silent myocardiac ischemia in stroke patients reflect previous reports in which 70% of the ischemic episodes in patients with symptomatic coronary artery disease are not associated with angina and in which approximately 10% to 15% of acute myocardial infarctions are silent. We now believe that the incidence of "silent" ischemia may be precipitated in poststroke patients during their rehabilitation program. This belief is supported by two main factors. First, a high level of personally relevant mental stress exists which activates the sympathoadrenal system, which may lead to myocardial ischemia. Second, some stroke patients become aphasic and are unable to communicate adequately even if they experience angina symptoms. We have found that poststroke, most patients could not undergo exercise treadmill testing secondary to a variety of factors: inability to coordinate limbs, poor endurance, inability to follow directions, and/or lack of attention. We now propose that 24-hour monitoring for ST-T wave changes poststroke should be considered as part of a vigorous investigation for myocardial ischemia during the rehabilitation of these patients because they have an increased risk of cardiac morbidity.     

Silent ischemia in rehabilitation patients: limited clinical utility of electrocardiographic monitoring.

In a prospective blinded trial, 24-hour continuous electrocardiographic monitoring for silent ischemia was used to try to identify rehabilitation patients at risk for cardiac complications. Five of 42 patients had episodes of silent ischemia, none of which occurred during physical therapy sessions. One of these patients had syncope while wearing the Holter; none of the other four patients had significant cardiac complications during their rehabilitation, and all were discharged home. None of the patients without ischemia on the monitor had complications, but two patients of 14 whose ECGs precluded monitoring for ischemia had complications. In addition, six patients had episodes of nonsustained asymptomatic ventricular tachycardia, 12 had episodes of supraventricular tachycardia, and four had significant ventricular ectopy, all without clinical significance. Despite the apparent high sensitivity and specificity of the technique, the positive predictive value of monitoring eligible patients for silent ischemia was 20%. We conclude that ambulatory electrocardiographic monitoring for silent ischemia or ectopy has limited clinical utility in the rehabilitation population.     

"Silent" myocardial ischemia and the activity of the sympathetic-adrenal system in hypertension patients

The aim of the study was to assess the sympathoadrenal activity at the time of silent ischemia event in hypertensive patients. In 15 hospitalized hypertensive patients having silent ischemia event during Holter ECG monitoring while walking, blood samples for catecholamines were taken at the time of silent ischemia event, pointed with alarm by the real time ECG "Q Med" monitor (USA). Control blood samples were taken under the same conditions without ST-segment depression. Plasma noradrenaline (NA) during silent ischemia was significantly higher than the control level without ischemia (458 +/- 71 ng/l vs 717 +/- 95 ng/l) (p less than 0.01). The changes in plasma NA correlated with left ventricular mass assessed by echocardiography (r = 0.70, p less than 0.01). The role of sympathoadrenal hyperactivity in the genesis of silent myocardial ischemia in patients with essential hypertension is discussed.     

Silent myocardial ischemia in long-term ECG with various mani festations of coronary heart disease

Silent myocardial ischaemia seems to be of prognostic value in coronary artery disease. We examined 47 patients with coronary artery disease: 1. 20 patients with a history of myocardial infarction (MI), 2. 15 patients with chronic stable angina pectoris without a history of myocardial infarction (sAP), and 3. twelve patients with unstable angina with or without a history of myocardial infarction (uAP). Horizontal and downsloping ST-segment-depressions greater than or equal to 1 min and greater than or equal to 0.1 mV were defined as significant. There were 132 ST-segment-depressions, the relation between symptomatic and asymptomatic being 1:7.3, in MI 1:6.2, in sAP 1:5.3, in uAP 1:14. Heart rate increased before beginning of ST-segment-depression in 74% in MI, in 86% in sAP, but only in 38% in uAP. In sAP ST-segment-depressions were smaller (14% greater than 0.2 mV, none greater than 0.3 mV) than in patients with MI (42% greater than 0.2 mV, 12% greater than 0.3 mV) and uAP (25% greater than 0.2 mV, 9% greater than 0.3 mV). Mean duration of ST-segment-depression was 15.3 +/- 11.7 min in sAP (2 to 49 min), 28.5 +/- 35.6 min in MI (2 to 168 min), and 41.2 +/- 40 min in iAP (2 to 140 min). ST-segment-depressions in MI and sAP showed a circadian rhythm with a peak at midday and in the early evening and a small amount of ST-segment-depressions at night. In uAP ST-segment-depressions did not show that circadian variation. The number of ST-segment-depressions was higher in uAP than in MI and sAP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Silent cardiac ischemia in cervical spinal cord injury: case study.

The management of ischemic heart disease in patients with chronic spinal cord injury (SCI) will become an increasingly major concern as this population ages. Although silent ischemia has become an important topic in the medical literature, the relationship with cervical SCI has not been adequately explored. A literature search revealed no case reports of documented asymptomatic cardiac ischemia in SCI patients. This is a case report of a 65-year-old patient with chronic C7 incomplete SCI who had multiple risk factors for coronary artery disease and an abnormal electrocardiogram. Despite being completely asymptomatic, the patient was found to have significant myocardial ischemia induced by minimal stress using atrial paced thallium scintigraphy. This finding led to the cancellation of an elective surgical procedure. This case illustrates the importance of suspecting silent myocardial ischemia in cervical SCI patients.     

Peripheral microcirculatory hemodynamic changes in patients with myocardial ischemia

BackgroundPatients with coronary heart disease demonstrate changes in skin microcirculation and a decrease in cutaneous blood mass.ObjectiveThe goal of this study was to assess the feasibility of diagnosing myocardial ischemia based on peripheral microcirculatory variables.MethodsThe skin microcirculatory measurements were monitored using an LPT system comprising a Laser Doppler Flowmeter (LDF), a photoplethysmograph (PPG) and a transcutaneous oxygen tension device (tc-PO₂). Concurrently, heart rate and blood pressure were monitored. Measurements were performed before and after exercise stress test. Subjects were divided into ischemic (20) and nonischemic (27) patients based on myocardial perfusion imaging (MPI).ResultsThe results indicate differences in LPT variables between ischemic and nonischemic patients following exercise, while no differences in the central variable values were observed between the two groups.ConclusionsPeripheral microcirculatory variables may be useful for non-invasive assessment of myocardial ischemia. The system has clinical potential for sensitive and noninvasive monitoring of vital variables during medical procedures in clinics, as well as in home care for patients who suffer from ischemic cardiac diseases.     

门控心肌灌注显像相位分析在2型糖尿病无症状性心肌缺血患者中的应用价值

目的探讨99mTc标记的甲氧基异丁基异腈(99mTc-MIBI)门控静息/运动负荷心肌灌注显像(MPI)相位分析在2型糖尿病无症状性心肌缺血(SMI)患者中的应用价值。方法将符合条件的53例行门控静息/运动负荷MPI扫描的2型糖尿病患者纳入研究,根据心肌灌注结果将其分为灌注正常组和灌注异常组。比较两组门控相关数据及BW、SD异常的发生率。结果灌注异常组左心室BW和SD均高于灌注正常组(P<0.01)。灌注正常组中左心室BW、SD异常的发生率均显著低于灌注异常组(P<0.01)。结论门控静息/运动负荷MPI通过一次检查既可得到患者的心肌血流灌注情况,同时也可以得到患者左室心肌运动同步性等室壁运动的相关数据,对2型糖尿病SMI患者具有重要价值。     

定量组织速度成像技术评价非胰岛素依赖型糖尿病患者心内膜下心肌缺血

目的应用定量组织速度成像(QTVI)技术测定非胰岛素依赖型糖尿病患者左室心肌收缩功能变化,以探讨糖尿病患者是否存在心内膜下心肌缺血。方法利用QTVI技术分别测量46例非胰岛素依赖型糖尿病患者和23例正常人的二尖瓣环收缩期长轴方向峰值运动速度(Sm)和室间隔左室面、右室面、左室后壁内外膜面下心肌短轴方向收缩期峰值运动速度(Vs)、收缩期心肌速度梯度(MVG)。M型超声测量二尖瓣环活动幅度(Dm)、左室射血分数(LVEF)。结果①糖尿病组与正常对照组的Dm、LVEF值均在正常范围,差异无统计学意义(P>0.05);②糖尿病患者Sm值减低[糖尿病组(6.01±1.50)cm/s对正常对照组(6.76±1.63)cm/s,P<0.05];③糖尿病患者室间隔和左室后壁的MVG值均低于正常对照组,差异有统计学意义[前室间隔:(-0.57±0.82)s-1对(-1.10±0.50)s-1;左室后壁:(1.38±0.97)s-1对(2.36±2.22)s-1)]。结论糖尿病患者左室心内膜下心肌收缩功能减低,提示患者存在左室心内膜下心肌缺血。