无症状心肌缺血阈的临床意义

目的评价无症状心肌缺血阈。方法62例冠心病患者，通过24小时心电监测，检测冠心病患者的心肌缺血阈值(MIT)、MIT的变异度(IV)，以及每阵缺血发作持续时间(TMI)和ST段最大位移(STm)，以及昼夜缺血阵数(IN)。结果共检出506阵心肌缺血，93．5％在ST段压低时心率加快，夜间心肌缺血阈值较低，但缺血时间及ST段压低程度明显重于昼间。结论高心肌缺血阈、低心肌变异率与心肌耗氧增加有关，低心肌缺血阈、高心肌变异率与冠脉痉挛有关。     

74例老年冠心病患者无症状心肌缺血临床探讨

目的 探讨老年冠心病患者无症状心肌缺血(SMl)的临床特点和发生规律。方法：对74例冠心病患者应用24h动态心电图检测(DCG)。按临床特征分为3组：Ⅰ组：单纯SMI；Ⅱ组：心绞痛患者伴有SMI；Ⅲ组：心肌梗死后有SMI发作。结果共检出心肌缺血634阵次，SMI的发生显著高于有症状心肌缺血，占90．22％。发作高峰在上午6～12点，Ⅰ Ⅱ Ⅲ组的SMI发作次数、持续时间、ST段压低幅度依次增加，心肌缺血幅度与病情呈正相关，而与心率变异性(HRV)呈负相关。00—06点最少．但夜间缺血持续时间及ST段压低幅度明显重于自昼。结论SMI是冠心病最常见的表现形式，应和有症状心肌缺血同样给予足够重视。冠心病患者心脏自主神经受损程度随着心肌缺血程度而加重。     

快速心房纤颤时ST段水平压低与冠心病关系的探讨

运动试验时，心电图ST段水平压低提示可能有心肌缺血。临床上快速心房纤颤(房颤)患者常伴有ST段水平压低，其是否合并冠心病临床尚难确定。本文对快速房颤时ST段水平压低患者进行冠状动脉造影，旨在探讨快速房颤时ST段水平压低与冠心病之间的关系。     

阵发性室上性心动过速患者ST段压低诊断冠心病的价值

探讨阵发性室上性心动过速(PSVT)发作时ST段压低是否由冠心病心肌缺血引起。对23例40岁以上窄QRS波的PSVT伴有1个以上导联ST段压低至少1mm的患者的心电图、冠心病危险因素和冠状动脉造影资料进行分析。结果:PSVT发作时ST段压低最大值与年龄、冠心病危险因素积分和心率均无明显相关性。23例患者中仅26%的患者诊断为冠心病;冠心病组与非冠心病组的冠心病危险因素积分有显著性差异,但二组性别、年龄、PSVT发作时心率、胸痛的发生率和ST段压低值均无显著差异。结论:40岁以上PSVT患者发作时ST段压低诊断冠心病的预测值较低,冠心病心肌缺血不是引起PSVT发作时ST段压低的唯一机制。     

异舒吉注射液治疗缺血性心脏病的护理观察

心肌缺血及缺血再灌注损伤的临床谱广泛，常用于各类型冠心病者及其介入性治疗、高血压性心脏病和糖尿病并发的心肌缺血以及各种原因导致的心肌缺血、慢性充血性心力衰竭。心肌缺血的主要症状是：发作性胸骨后疼痛、胸闷、呼吸困难，活动后加重。典型心电图改变为：ST段压低≥0．05mV，T波低平或倒置。有的患者可无症状，但静息时或负荷试验后有典型的ST—T改变。     

13O例无症状性心肌缺血的动态心电图观察

近年来观察冠心病患者无症状性心肌缺血的发生远较心绞痛时为多.本文对诊断明确的130例冠心病患者(其中心绞痛92例、陈旧性心肌梗塞38例)进行24h动态心电图检查发现,无症状性ST段缺血型压低的次数为508次,而伴心绞痛的ST段压低的次数仅为66次,两者有显著性差异(X~2=7.21,P<0.01).我们认为心肌缺血发作不引起疼痛可能与下列因素有关:(1)缺血心肌的范围较小,缺血的时间短促,     

动态心电图对无症状心肌缺血的评价

目的：探讨动态心电图（Holter）一过性ST段压低对无症状心肌缺血的诊断价值。方法：应用Holter监测152例冠心病患者心肌缺血发生阵次、每次缺血发作时间和ST段最大下移，并行冠状动脉造影检查。结果：Holter监测的152例无症状心肌缺血患者中，冠脉造影检查示冠状动脉有意义狭窄者149例（98％）；单纯无痛性心肌缺血（SMI）123例（81％）；伴其他时段典型心绞痛29例（19％）；心肌缺血发作时，快频率依赖者107例（70％）；昼夜发作规律为6：00～12：00发生最高，这期间检出523阵次，占78％。结论：Holter检出的无症状心肌缺血绝大部分为冠脉病变引起．对于冠心病的诊断和疗效评定有重大价值。     

冠心病病人无症状性心肌缺血的临床分析

目的 探讨如何对无症状性心肌缺血（SMI）的冠心病病人进行早诊断及有效防治。方法 对126例冠心病病人进行24h动态心电图监测，据ST段压低情况及其同临床症状、发作时间、持续时间、心率变化及日常活动的关系做定性、定量分析。结果 126例中无症状性心肌缺血者79例，其中单纯性无症状性心肌缺血53例，无症状缺血型ST段压低发生次数是有症状的4.2倍。结论 并非每一位冠心病病人都有胸痛或与心肌缺血相关的主观症状，有一部分病人心电图表现为心肌缺血，但无胸痛或与心肌缺血相关的主观症状。     

100例无症状性心肌缺血的动态心电图观察

据多年来临床实践观察 ,冠心病患者无症状心肌缺血的发生率远较心绞痛为多 ,本文对已确诊的 1 0 0例冠心病患者 (其中心绞痛 72例 ,陈旧性心肌梗死2 8例 )进行 2 4小时动态心电图观察 ,发现无症状性ST段缺血型压低的次数为 40 3次 ,而伴心绞痛的 ST段压低的次数仅为 38次 ,两者之间有显著差异。心肌缺血发作时可引起疼痛 ,但并不是所有的心肌缺血都引起疼痛。本人认为心肌缺血发作不引起疼痛可能与下例因素有关。 1缺血心肌的范围较小 ,缺血的时间短促 ,刺激不足 ;2神经系统疼痛报警系统失灵 ,疼痛传至大脑皮层的径路发生障碍 ;3患者痛阈…     

24 h动态心电图检测冠心病无症状心肌缺血阈的临床分析

目的探讨动态心电图对冠状动脉粥样硬化性心脏病（冠心痛）病人无症状心肌缺血闽值的临床意义。方法53例冠心病病人24h心电图检测其心肌缺血闽值、心肌缺血闽值的变异度、每阵缺血发作持续时间和ST段最大位移，以及昼夜缺血次数。结果共检出468例缺血发作，以心率加快时心肌缺血居多，达91．2％，夜间心肌缺血闽值较低，且缺血持续时间及ST段压低程度明显长于厦重于白昼。心肌缺血阈的变异度为22．3％。与缺血总阵数呈正相关。结论高心肌缺血阈与心肌耗氧量有关，低心肌缺血闽与冠状动脉张力有关。     

冠心病无症状性心肌缺血的动态心电图表现及其诊断价值

目的：应用动态心电图（DCG）检测冠心病（CAD）的无症状性心肌缺血（SMI）,以探讨其发生率、发病规律、病情和预后关系。并由此评价DCG诊断SMI及指导临床治疗的应用价值。方法：采用12导联DCG记录系统,对224例CAD患者连续监测24h,回放分析观察ST段移位值;心肌缺血阈等指标。结果：224例CAD患者中发生心肌缺血204例（91．07％）,共检出694次心肌缺血发作,而其中589次为SMI（84．87％）;心肌缺血性ST段下移发作以6：00～12：00时最为频繁。而0：00～6：00时出现最少;夜间缺血ST段下移持续时间延长,心肌缺血阈变异性值增高;心率越快,诱发的心肌缺血越严重,ST段下移越明显。结论：DCG是较理想的诊断SMI的非创伤性辅助检查方法。     

Role of increases in heart rate in determining the occurrence and frequency of myocardial ischemia during daily life in patients with stable coronary artery disease.

OBJECTIVES. The goal of this study was to investigate the role of increases in heart rate in the development of ischemic episodes recorded during ambulatory electrocardiographic (ECG) monitoring in patients with stable coronary artery disease and to establish the importance of such increases in determining the frequency of ambulatory myocardial ischemia. BACKGROUND. The factors that determine the occurrence and frequency of episodes of myocardial ischemia that patients with stable coronary artery disease experience during daily life have not been clearly defined. In particular, the role of increases in heart rate in the development of myocardial ischemia is controversial. METHODS. To address these issues, 54 patients (42 men and 12 women, mean age 60.5 +/- 8 years) with proved coronary artery disease who had > or = 1 mm ST segment depression during exercise testing underwent an exercise treadmill test with use of the National Institutes of Health combined protocol and a 48-h period of ambulatory ECG monitoring. The exercise ischemic threshold was determined as the heart rate at the onset of ST segment depression during exercise testing. RESULTS. During monitoring, 48 (89%) of the 54 patients had at least one episode of ST segment depression (mean +/- SD 6.6 +/- 5 episodes, range 0 to 22). The majority (320 of 359 or 89%) of ischemic episodes were preceded by an increase in heart rate > or = 10 beats/min; the most significant increase (22.3 +/- 10 beats/min) occurred during the 5-min period before the onset of the episode. An ischemic episode occurred 80% of the times the heart rate reached the exercise ischemic threshold. A strong correlation was observed between the number of times the exercise ischemic threshold was reached during monitoring and both the number and the duration of ischemic episodes (r = 0.90 and 0.71, respectively, p < 0.0001). CONCLUSIONS. Increases in heart rate that exceed the exercise ischemic threshold are commonly observed before the onset of episodes of ambulatory myocardial ischemia in patients with stable coronary artery disease. Moreover, such increases constitute an important determinant of the frequency of myocardial ischemia during daily life. These findings may explain the variability observed in the number of ischemic episodes and may have important implications for the mechanisms that contribute to myocardial ischemia in daily life and for the clinical evaluation of patients with coronary artery disease.     

心绞痛患者528次缺血性ST段下移分析

83例心绞痛患者经24小时动态心电图监测到528次缺血性ST段下移,分析结果表明:1.在心绞痛患者缺血性ST段下移中,无症状性心肌缺血占75％,发生次数是有症状的3倍;2.缺血性ST段下移,85％与活动有关;3.缺血性ST段下移有明显的昼夜分布规律,上午6—10时为发作高峰,占全天总次数32％。提示在冠心病治疗中应重视包括无症状性心肌缺血在内的总缺血负荷,并结合缺血的昼夜分布规律调整给药时间。     

Coronary heart disease and silent myocardial ischemia]

Silent myocardial ischemia was studied in 100 patients with coronary heart disease (CHD), proved by the coronary arteriogram (at least one major coronary artery narrowed by > or = 50%). The study demonstrated that 51 of 100 patients with CHD had episodes of myocardial ischemia by Holter monitoring. In the 51 patients, during daily activities, through 24-hour Holter monitoring, 239 transient episodes of ST depression were detected, 161 of the total were asymptomatic (67.4%). There were no statistically significant differences in the heart rate and the product of heart rate and systolic blood pressure before ST depression between asymptomatic and symptomatic episodes. The heart rate at the time of maximal ST depression during both asymptomatic and symptomatic ischemia increased by 13 and 22 beats/min, respectively, over those before ST depression (P < 0.01); whereas the increase in heart rate during symptomatic ischemia was more significant than during asymptomatic ischemia (P < 0.01). The increase of product of heart rate and systolic blood pressure at the time of maximal ST depression during asymptomatic and symptomatic ischemia were 22.2 and 35.4, respectively, over those before ST depression (P < 0.01). The incidence of silent ischemic episodes in patients with single vessel disease was 81.7% and those with multivessel disease was 61.3% (P < 0.01). The frequency of silent ischemic episodes was maximal (36% of total number of ischemic episodes) between 6 a.m. and 12 a.m. during 24-hour, whereas the incidence of silent ischemic episodes in patients with single vessel disease was similar to that in patients with multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term variation in myocardial ischemia during daily life in patients with stable coronary artery disease: its relation to changes in the ischemic threshold.

Long-term variation in the frequency of myocardial ischemia during daily activity in patients with coronary artery disease who do not experience symptomatic changes has not been documented. Because at one point in time, the magnitude of such ischemia is strongly related to the ischemic threshold measured during exercise testing, this study was undertaken to determine whether patients with stable coronary artery disease show long-term variations in the frequency and duration of myocardial ischemia and to establish whether such variability is related to parallel changes in the ischemic threshold during exercise testing. Forty consecutive patients (mean age 61 +/- 8 years) who showed a stable clinical course over greater than or equal to 12 months were studied with a repeat exercise treadmill test and ambulatory electrocardiographic (ECG) monitoring after withdrawal of antianginal medications. The ischemic threshold was determined as the exercise time at 1 mm of ST segment depression. The mean interval to both follow-up evaluations was 15 +/- 3 months. Among the 23 patients with myocardial ischemia on ambulatory ECG monitoring at initial evaluation, the number and duration of ischemic episodes at follow-up were increased in 5 patients (mean increase 3.6 +/- 2 episodes and 123 +/- 98 min), unchanged in 1 patient and decreased in 17 patients (mean decrease 2.6 +/- 2 episodes and 98 +/- 72 min). Of the 17 patients without ischemic episodes at initial evaluation, 3 had evidence of ischemia on follow-up ambulatory ECG monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitation of transient myocardial ischemia by digital, ambulatory electrocardiography

Transient myocardial ischemia is more frequently silent than accompanied by angina. The frequency of ischemia varies markedly from day to day, so that in order to accurately define the total ischemic burden, it may be necessary to quantitate ischemic episodes for periods longer than 24 hours. Therefore, a programmable, digital device was developed for long-term, interactive, ambulatory monitoring of the electrocardiogram, which uses variations in a time-averaged ST level as an indicator of myocardial ischemia. The electrocardiographic signal is digitized at 256 Hz and analyzed by an algorithm. If ST depression is planar or downsloping and persists for more than 40 seconds, and if the ST depression is equal to or more than a user-programmed threshold, the device marks the onset of an ischemic event and times it. The algorithm has been validated by comparison of its analysis of the ST segment to human and computerized analyses of frequency-modulated Holter recordings and stress tests. To assess the feasibility and utility of long-term monitoring, patients with documented coronary artery disease were monitored continuously for 14-day periods. Of 26 patients enrolled, 8 completed a protocol for individualization of anti-ischemic therapy using transdermal nitroglycerin. Over 90% of ischemic episodes in this group of patients, all of whom had had a previous myocardial infarction, were silent. Treatment with 10 mg of transdermal nitroglycerin reduced the number of ischemic episodes by 59% and the duration of ischemia by 60% (p less than 0.001); there was no diminution in the effectiveness of treatment from week 1 to week 2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic value of total ischemic burden in patients with stable ischemic heart disease.

Patients with stable coronary artery disease commonly have transient myocardial ischemia with or without experiencing angina, but the prognostic implications of this "total ischemic burden" is still a matter of debate. We studied 112 consecutive patients with coronary artery disease, normal left ventricular function at rest and exercise-induced myocardial ischemia, a 24-hour ambulatory EKG was performed after drug withdrawal. The mean exercise duration was 572 +/- 192 seconds, with an ischemic threshold (ST depression = 1 mm) of 390 +/- 190 seconds). By Holter monitoring 30 patients had no ischemia and 82 (73%) had a total of 332 episodes of ST segment changes, the majority of which were asymptomatic (242/332, 73%). Among 82 patients with transient myocardial ischemia, 44 (54%) had only asymptomatic episodes. Nine patients (11%) complained of angina coincident to ST changes. Twenty-nine patients (35%) had both painful and painless ST segment alterations. All patients were prospectively followed-up while on conventional medical therapy. During a mean follow up of 25 +/- 10 months cardiac events occurred in 31 patients; there were 5 cardiac deaths, 3 non-fatal myocardial infarctions, 2 hospitalization for unstable angina and 21 revascularization procedures (PTCA or CABG). By multivariate analysis the number of stenotic vessels on coronary angiography was predictive of the events during the follow-up (p = 0.03), while other demographic, clinical, ergometric and angiographic variables were not influential. Event-free survival was similar for all subsets of transient myocardial ischemia (silent, symptomatic, or none).(ABSTRACT TRUNCATED AT 250 WORDS)     

Transient ST-segment depression as a marker of myocardial ischemia during daily life

Patients with angina and coronary artery disease (CAD) have many episodes of transient ST-segment depression during ordinary daily life, and these are often asymptomatic. To investigate this signal as a marker of myocardial ischemia, 30 patients with chronic stable angina and CAD underwent positron tomography, recording the regional myocardial uptake of rubidium-82, pain and ST-segment changes before, during and after 59 technically satisfactory exercise tests, 35 cold pressor tests and 22 episodes of unprovoked ST depression. Exercise resulted in 53 episodes of ST depression with angina and in 5 episodes without pain. After cold pressor tests, there were 3 episodes of ST depression and pain and 12 of painless ST depression. Only 9 episodes of unprovoked ST depression were accompanied by pain. Tomography showed independent evidence of ischemia in 63 (97%) of the total 65 episodes of ST depression with angina and in all 30 episodes of painless ST depression. In each patient perfusion defects occurred in the same myocardial segment during painful and painless ST depression and responses were significantly different from those in 16 normal subjects studied in the same way. These findings support the use of transient ST depression in continuous monitoring to assess the activity of CAD, but only in patients with typical angina pectoris, ST depression during exercise and proved CAD. They strengthen the evidence derived from ambulatory monitoring for a wider picture of the disease than is generally appreciated, with more frequent episodes of silent myocardial ischemia than of angina pectoris.