心肌灌注造影在多巴酚丁胺负荷前后早期诊断冠心病的临床研究

目的探讨心肌灌注造影(MCE)技术在大剂量多巴酚丁胺负荷前后早期诊断冠心病的价值.方法 对临床疑为冠心病患者38例,进行大剂量多巴酚丁胺负荷超声心动图试验,分别在静息状态和多巴酚丁胺负荷超声心动图试验终止时即刻行MCE检查.以冠状动脉造影为金标准将大剂量多巴酚丁胺负荷超声心动图前后心肌灌注状态目测法对冠心病的检出率进行比较.结果 多巴酚丁胺负荷超声心动图检查的38例患者中,9例(24%,9/38)达到峰值负荷水平,22例(58%,22/38)达到中级负荷水平.其中通过冠状动脉造影诊断的27例冠心病患者在多巴酚丁胺负荷前后,通过心肌灌注状态目测法诊断心肌缺血患者的例数分别为10例(37%,10/27)及24例(89%,24/27,χ2=15.565,P＜0.01).结论 大剂量多巴酚丁胺负荷超声心动图结合MCE可提高缺血心肌的检出率,发现隐匿性心肌缺血,为临床无创性诊断早期冠心病患者提供新方法.     

The higher likelihood of developing cardiomegaly during follow-up in patients with syndrome X and abnormal thallium-201 myocardial perfusion SPECT

`Syndrome X' describes patients with exertional chest pain and a normal coronary arteriogram. In some patients, acute myocardial ischemia can be demonstrated by regional myocardial perfusion defects on thallium-201 exercise test. However, some patients with typical angina have normal perfusion on thallium-201 heart scintigraphy. It is not clear whether there are different prognoses for patients with normal and abnormal thallium studies. In this study, the clinical features, long term follow-up and clinical results of syndrome X patients with normal and abnormal thallium studies were evaluated to determine the differences between these two groups. Fifty-nine patients (52 males, seven females, mean age 62 ± 6 years) with syndrome X were enrolled and divided into two groups on the basis of results of thallium-201 heart scintigraphy. Group I was comprised of 22 patients with normal thallium-201 perfusion scan and group II was comprised of 37 patients with abnormal thallium-201 heart scan. All subjects received coronary arteriography, exercise test, thallium-201 myocardial SPECT, ejection fraction of left ventricle, echocardiography, blood analysis and long term follow-up with questionnaire for 10 years. Lower maximal rate–pressure product and higher angina scores were found in group II. More patients developed cardiomegaly (nine of 33 patients) in group II than in group I (one of 21 patients). Both groups, however, were at low risk for cardiac events (cardiac death or myocardial infarction).     

Diagnostic value of ischaemia-modified albumin for predicting myocardial ischaemia during myocardial perfusion scintigraphy

During acute ischaemia the N-terminal site of albumin is altered, reducing its binding capacity; the modified protein is termed ischaemia-modified albumin (IMA). IMA is a sensitive marker of acute myocardial ischaemia but its diagnostic value in chronic angina pectoris patients is unclear. We investigated changes in blood levels of IMA during myocardial perfusion scintigraphy in patients with chronic angina pectoris in a study including 26 male and 20 female patients, with mean age 60 years. Technetium 99m perfusion imaging detected myocardial ischaemia in 26 patients. Coronary angiography was carried out in these 26 ischaemic patients. Mean IMA values at rest and peak exercise were significantly higher in the ischaemic than the nonischaemic group. All IMA values were considered negative for cardiac ischaemia. Peak exercise IMA was significantly lower than the pre-exercise level only in the non-ischaemic group. IMA measurements during myocardial perfusion scintigraphy are not helpful in the diagnosis of myocardial ischaemia in patients with stable angina pectoris.     

心肌梗死患者超急性期心肌超声背向散射参数检测及其意义

目的 应用心肌组织超声背向散射积分(IBS)分析健康人及心肌梗死患者超急性期的心肌运动变化及其意义.方法 将38例急性心肌梗死(AMI)患者于超急性期(梗死时间在2 h内)及急性期(梗死时间＞2 h,有典型的心电图改变)进行心肌超声背向散射参数检测,另设健康对照组25例.分别测量心肌梗死区域和非梗死区域心肌组织的心动周期时间平均背向散射积分(IBS),并将其与心包IBS的比值作为心肌IBS的校正值(IBS%),舒张末期与收缩末期的IBS差值即IBS的周期变化幅度(CVIB),并将其与心包IBS的比值作为心肌CVIB的校正值(CVIB%).同期作心电图、心肌酶谱及心肌肌钙蛋白I检测.结果 当AMI超急性期患者心电图还无典型变化时,心肌梗死部位的IBS值已经明显大于健康对照组[(43.7±10.8)dB比(22.6±4.6)dB,P＜0.01],而CVIB 明显小于健康对照组[(10.2±2.6)dB比(13.2±3.8)dB,P＜0.01].急性期患者其IBS明显高于健康对照组及患者非梗死部位,而CVIB明显小于健康对照组及患者本身非梗死部位.且与心电图变化完全一致.结论 心肌超声背向散射参数有助于AMI超急性期诊断,并可判断心肌病变的范围和程度.     

多巴酚丁胺负荷超声心动图结合心肌灌注造影早期诊断冠心病的价值

目的 探讨大剂量多巴酚丁胺负荷超声心动图(DSE)结合心肌灌注造影(MCE)技术早期诊 断冠心病的价值。方法 对临床可疑冠心病的38例患者进行大剂量多巴酚丁胺负荷试验,分别在静息状态和试验终止的即刻实行MCE检查。并在静息状态及各级负荷状态下观察室壁运动(WM)情况;对每次MEC后各心肌节段灌注状态进行评估。大剂量DSE时,以冠状动脉造影为金标准比较WM目测法和心 肌灌注状态目测法诊断冠心病的敏感性和特异性。结果 DSE时,9例(24％)患者达到峰值负荷水平,22 例(58％)达到中级负荷水平。DSE终止时,通过心肌灌注状态目测法及WM目测法诊断有心肌缺血患者 的例数分别为24例(89％)及15例(52％)(P＜0.01)。同时,通过上述两组方法评估心肌缺血,并根据相应缺血心肌节段所对应冠脉分支准确判断病变血管的敏感性分别为71％及41％(P ＜0.01)。结论 大剂量DSE结合心肌灌注造影可以提高检出缺血心肌的敏感性,发现隐匿性心肌缺血,为临床诊断早期冠心 病患者提供了无创性新方法。     

Clinical experience with technetium-99m teboroxime scintigraphy in patients referred for myocardial perfusion evaluation

A series of 30 patients (25 males, 5 females, age=28–73 years) with a clinical indication of thallium-201 stress/4 hours redistribution scintigraphy has been studied using stress/rest (n=7) or rest/stress (n=23) protocols with technetium-99 m teboroxime (CARDIOTEC, Squibb Diagnostics) in order to assess the clinical usefulness of this new molecule and to compare it to thallium. In all cases coronary artery disease was known or highly suspected, with a history of myocardial infarction in 18 cases (subacute n=6, remote n=12) and/or previous by-pass surgery or PTC A in 5 cases. Medical treatment was not discontinued at the time of stress testing. Coronary angiography was available for 27 patients. Exercise tests for both tracers were carried out on an ergometric bicycle during the same day and the levels of exercise achieved for the thallium studies were very similar to those achieved for teboroxime. Imaging was performed in three planar projections and sudies were evaluated using a model with 4 territories: septal and anterior assumed to correspond to the LAD artery, lateral and latero-posterior (=LCX), inferior and posterior (=RCA) and apex. Classification of results was: normal, ischemic, infarcted and infarcted with ischemia. With reference to the thallium-201 results, agreement was found in 86% (37/43) of normal regions and in 82% (63/77) of abnormal regions. Relative to documented coronary artery lesions (27 patients) sensitivity and specificity of thallium and teboroxime for exact correspondence between arteries and territories were, respectively: thallium, se=71%, sp=64%, teboroxime, se=67%, sp=75%. These results indicate the ability of Cardiotec to evaluate myocardial perfusion with an important time saving since the complete study durations (stress and rest) were: thallium=4h 34 min ?22 min and teboroxime=1 h 57 min ?41 min.     

Pathology of cardiac transplantation: recipient hearts (chronic heart failure) and donor hearts (acute and chronic rejection).

Pathologic examination of both the recipient and the donor heart is critical to the success of cardiac transplantation. Idiopathic dilated cardiomyopathy and end-stage ischemic heart disease are still the most common diagnoses for which cardiac transplantation is performed in the United States. After transplantation, the donor heart is susceptible to immunologic (acute and chronic rejection), infectious, and ischemic injury. Other long-term changes, such as hypertrophy of the myocytes and interstitial fibrosis, may also affect the function of the transplanted heart. Periodic endomyocardial biopsies are important for monitoring the status of the transplanted heart. In patients treated with cyclosporine, the clinical signs of rejection may be minimal, and routine biopsy is the only means of detecting early rejection.     

The effect of captopril on thallium 201 myocardial perfusion in systemic sclerosis

In systemic sclerosis, abnormalities of myocardial perfusion are common and may be caused by a disturbance of the coronary microcirculation. We evaluated the long-term effect of captopril (75 to 150 mg per day) on thallium 201 myocardial perfusion in 12 normotensive patients with systemic sclerosis. Captopril significantly decreased the mean (+/- SD) number of segments with thallium 201 myocardial perfusion defects (6.5 +/- 1.9 at baseline and 4.4 +/- 2.7 after 1 year of treatment with captopril; p less than 0.02) and increased the mean global thallium score (9.6 +/- 1.7 at baseline and 11.4 +/- 2.1 after captopril; p less than 0.05). In a control group of eight normotensive patients with systemic sclerosis who did not receive captopril, no significant modification in thallium results occurred. Side effects with captopril included hypotension (six patients), taste disturbances (one patient), and skin rash (one patient). These side effects subsided when the dosage was reduced. These findings demonstrate that captopril improves thallium 201 myocardial perfusion in patients with systemic sclerosis and may therefore have a beneficial effect on scleroderma myocardial disease.     

Prognostic value of real time dobutamine stress myocardial contrast echocardiography in patients with chest pain syndrome

The aims of this study were (1) to evaluate the prognostic value of negative wall motion (WM) and myocardial perfusion during contrast-dobutamine stress echocardiography (DSE), (2) to determine whether WM-myocardial contrast echocardiography (MCE) had incremental prognostic value over just WM during DSE in patients with chest pain in the emergency room (ER), and (3) to compare the prognostic value of negative DSE-WM, and DSE-WM-MCE to nuclear-myocardial perfusion imaging (N-MPI) in a similar patient population over the same time period. We retrospectively studied 569 patients with real time contrast DSE, and 147 patients underwent N-MPI for evaluation of chest pain. Follow-up for cardiac events was obtained between 12 and 25 months. The cumulative cardiac event-free survival was 94.5% in negative DSE-WM, 97.1% in negative DSE-WM-MCE and 96.7% in negative N-MPI group. Cardiac event-free survival of the negative DSE-WM-MCE group was significantly higher than the DSE-WM group (log rank P < 0.01), and similar in the DSE-WM-MCE group compared to the N-MPI group. Combined WM and perfusion during DSE was the strongest independent predictor for cardiac events. The negative predictive power of DSE-WM-MCE is superior to that of just negative DSE-WM and is comparable to that of N-MPI. Myocardial perfusion and WM analysis during DSE provide independent information for predicting cardiac events in patients with chest pain syndrome in the ER.     

多普勒组织显像在冠心病诊断中的应用研究

本研究应用多普勒组织显像技术以正常人检测结果为基础,评价心绞痛、急性和陈旧性心肌梗塞病人的心肌缺血和梗塞的部位及程度。同时将其应用于多巴酚丁胺药物负荷试验。以上评价结果均与ECT~(99m)Tc心肌血流灌注显像结果进行比较。结果发现:多普勒组织显像显示缺血和硬塞部位心肌存在与正常心肌不同的异常速度和加速度分布,此分布有明显边界。多普勒组织显像在较低药物负荷剂量下显示了轻微的室壁异常运动及其变化。多普勒组织显像所示心肌缺血和梗塞部位与ECT检测心肌缺血和梗塞部位的吻合率分别为67%和80%;辅助多巴酚丁胺药物负荷试验所示心肌缺血和梗塞部位与后者的吻合率为86%。结果表明:多普勒组织显像能够较为准确、直观地反映心肌缺血和梗塞的部位和程度,从而提高了超声心动图评价冠心病的准确性和效率。进一步控制多普勒组织显像的影响因素是提高诊断质量的关键。     

Mechanisms of regional wall motion abnormalities in contrast-enhanced Dobutamine Stress Echocardiography

BACKGROUND: In the diagnosis of coronary artery disease (CAD) with Dobutamine Stress Echocardiography (DSE), regional wall motion abnormalities (RWMA) are assumed to indicate a perfusion deficit. METHODS AND RESULTS: For a more particular examination of RWMAs, we compared simultaneous echo-contrast (Optisone)-enhanced DSE (0-40 microg/kg Dobutamine, 16-segment- model) and MiBi-SPECT in a prospective double-blinded study design in 69 non-selected consecutive patients (44 male, 25 female, age 64+/-12 years). Additionally, all patients were examined by coronary-angiography. The prevalence of significant CAD (stenosis >50% lumen diameter) was 52%. DSE had a sensitivity of 78% and a specificity of 66% for the detection of significant CAD with a positive and negative predictive value of 72 and 73%, respectively. Among 28 patients with significant CAD and positive DSE study (true positive), 78% displayed a corresponding perfusion deficit in MiBi-SPECT. Among 11 patients with a positive DSE study but no current significant coronary stenosis (false positive), 82% showed stress-induced RWMAs in the inferior/posterior region, 73% displayed left ventricular hypertrophy, 54% resting-ECG abnormalities and 45% resting-RWMA (3 previous MI, 2 previous CABG surgery). Among 8 patients with negative DSE study but significant coronary stenosis (false negative), 75% had a stenosis of the LCX, 63% displayed resting- WMA, 63% displayed left bundle branch block or ST-segment depression, 50% displayed only peripheral coronary stenosis, and DSE visualization was suboptimal in 38%. CONCLUSION: This prospective study in non-selected patients shows that the majority of RWMAs in DSE are matched to a perfusion deficit detectable by nuclear imaging. Nevertheless, pre-existing cardiac abnormalities may also lead to stress-induced RWMA not associated with a perfusion deficit or mask a perfusion deficit upon DSE. Particularly in patients with LV hypertrophy, resting-RWMA, bundle branch block or ST segment depression, the predictive value of DSE may, therefore, be limited.     

原发性高血压患者心肌灌注显像的影像表现

目的:对59例原发性高血压患者进行心肌灌注显像,分析其影像特点。方法:对59例患者进行SPECT负荷心肌灌注显像,由3位医生分别进行读片(双盲法),分析其影像表现,以6壁段方式分别判断是否有左心室心肌肥厚、灌注异常等征象,有2位以上判断相同者为有效,并记录备用。结果:59例原发性高血压患者负荷心肌灌注显像的影像表现为灌注异常和节段性心肌肥厚,具有多壁段、多病灶的特点。本文47/59例患者呈现灌注异常,检出率为79·7%;37/59例患者呈现节段性心肌肥厚,检出率为62·7%;在37例节段性心肌肥厚者中有26例同时存在灌注异常,节段性心肌肥厚者并发灌注异常的发生率为70·3%。结论:原发性高血压患者负荷心肌灌注显像常常表现为灌注异常和节段性心肌肥厚,具有多壁段、多病灶的特点,而这些表现与高血压患者冠状动脉血流储备能力的改变有关。     

Evaluation of myocardial perfusion in patients with hypertrophic cardiomyopathy in comparison with clinical and echocardiographic data

AIM: To study peculiarities of myocardial perfusion in patients with hypertrophic cardiomyopathy (HCMP) in correlation with clinical and echocardiographic data. MATERIAL AND METHODS: 62 patients with HCMP (23 females and 39 males, mean age 44.4 +/- 11.2 years, the disease duration 13.0 +/- 10.4 years) have undergone ECG, 24-h ECG monitoring, echocardiography, perfusion scintigraphy of the myocardium with 99m-TcMIBI at rest and in combination with bicycle ergometry. The patients were divided into two groups: 35 patients of group 1 had moderate left ventricular hypertrophy (the septal thickness in diastole under 20 mm; 27 patients of group 2 had severe hypertrophy (the thickness was over 20 mm). RESULTS: Dyspnea and syncopal states occurred more frequently in patients from group 2. They also had a higher functional class of heart failure (2.0 +/- 0.8 and 1.2 +/- 0.7 for group 1 and 2, respectively, p < 0.05). Cardiac performance was significantly higher in patients of group 1. The size of the left atrium, left ventricular myocardium mass, the septal thickness and thickness of posterior wall of the left ventricle, gradient of pressure in the outflow tract of the left ventricle proved higher in patients of group 2. Deep stable defects of myocardial perfusion were detected in 5 (15%) patients of group 1 and 10 (37%) patients of group 2. Transient defects of myocardial perfusion were found in 9 (26%) patients of group 1 and 12 (44%) patients of group 2. The index of myocardial ischemia in group 1 patients was significantly lower than in patients of group 2 (3.5 +/- 2.2 and 8.3 +/- 2.5, respectively, p < 0.05). CONCLUSION: Patients with severe hypertrophy of the left ventricle had severe clinical picture, low exercise tolerance, marked hemodynamic changes, more frequent defects of left ventricular perfusion defects compared to patients with moderate hypertrophy of the left ventricular myocardium.     

小剂量多巴酚丁胺负荷超声心动图试验对可逆性功能障碍心肌预测的新指标

目的：探讨小剂量多巴酚丁胺负荷超声心动图（DSE）试验中左心室功能EF值的变化,即ΔEF这一量化指标预测急性心肌梗死（AMI）后患者的功能障碍心肌是否可逆及其可恢复程度。方法：入选患者25例, 接受小剂量DSE检查,测定负荷试验各阶段的收缩功能EF值,25例患者亦接受冠脉造影,并择期行经皮经腔太动脉成形术（PTCA）治疗,根据病变血管的情况植入支架,在术后3．5－13个月之间复查小剂量DSE试验。结果：以小剂量DSE过程中EF增加值,即ΔEF大于等于15％作为衡量标准,预测可逆性功能障碍心肌的敏感性,特性和准确性分别为70．6％,75％和72％,此预测改善值与无改善值之间的差异有显著性意义（P＜0．05）,结论：ΔEF可以作为准确评价可逆性功能障碍心肌的指标,并且是一种定量测定方法。     

腺苷负荷心肌核素显像在冠心病诊断与介入治疗中的作用

目的探讨腺苷负荷心肌核素显像在冠心病诊断及介入治疗中的作用。方法冠心病的可疑患者,行腺苷负荷心肌核素显像,部分患者进行冠脉造影和介入治疗,介入治疗前后进行腺苷负荷心肌核素显像检查对比。腺苷负荷心肌核素显像采用单光子发射断层显像图像采集系统,腺苷总量为840μg/kg静脉泵入,3 min后静脉推注99mTc-MBI925 MBq,90 min后进行心肌断层显像,如果发现心肌显像异常,次日再行静息心肌显像。结果134例冠心病患者,年龄21~85(63.3±14.8)岁,男90例,女44例,进行腺苷负荷心肌核素显像,109例提示有心肌缺血现象,25例正常,诊断阳性率达81.3%。12例患者经过冠状动脉造影,有冠脉狭窄的患者行PCI,前后复查腺苷心肌核素显像,介入后心肌核素血流灌注较介入前明显改善(P<0.01)。结论腺苷负荷心肌核素显像在冠心病的诊断中起着重要的作用,其敏感性与特异性较高,同时在冠心病介入治疗前后疗效评价方面有一定的临床意义。     

背向散射积分、组织多普勒与核素扫描对心肌缺血和存活的相关性临床研究

目的:进一步探讨组织多普勒和组织定征技术临床应用的可行性。方法:12例超声发现节段性室壁运动失常患者分别进行多巴酚丁胺负荷超声心动图、超声组织多普勒、背向散射积分及核素扫描检查。结果:有收缩储备节段背向散射积分曲线形态评分较无收缩储备节段明显降低,背向散射积分周期变异幅度(CVIB)、T波顶点时心内膜运动速度(Vendo)、心肌中部心动周期中最大运动速度(TVC)、收缩期心肌运动速度峰值跨壁梯度(MVGm+)及放射性核素摄取率均较无收缩储备节段显著增高,有收缩储备节段背向散射积分平均值(AII)与无收缩储备节段的差别无显著性。心肌收缩期运动指标与CVIB正相关,与AII负相关。放射性核素摄取率与TVC、Vendo、MVGm+正相关,与AII负相关,与CVIB相关呈临界状态。结论:背向散射积分和组织多普勒指标在判断心肌缺血与存活的临床应用方面有很大潜力。     

Dipyridamole stress ultrasonic myocardial tissue characterization in patients with Kawasaki disease.

Dipyridamole stress integrated backscatter (IBS) was used for evaluation of myocardial ischemia or damage in 31 children with coronary artery lesions caused by Kawasaki disease, in comparison with thallium-201 myocardial imaging. All patients underwent echocardiography at rest and after dipyridamole stress at the anterior interventricular septum, posterior wall (PW), and inferior wall (INF). At rest, no significant difference was seen in cyclic variation (CV) of IBS in the regions with normal or abnormal distribution on Tl-201 imaging. But in the regions showing abnormal distribution after stress, CV decreased significantly. A delayed study after stress showed the recovery of CV to the level at rest in all patients. Sensitivity of abnormal cyclic variation integrated backscatter was 75% in the PW and 91% in the INF, and specificity was 91% in the PW and 90% in the INF, compared with the results of thallium-201 imaging. Dipyridamole stress IBS can provide sensitive detection of myocardial ischemia or damage in Kawasaki disease.     

Detection of residual tissue viability within the infarct zone in patients with acute myocardial infarction: ultrasonic integrated backscatter analysis versus dobutamine stress echocardiography.

OBJECTIVES: The goals of this study were to analyze temporal changes in cardiac cyclic variation of integrated backscatter (CVIB) in acute myocardial infarction (AMI) and to investigate the predictive value of CVIB normalization compared with that of dobutamine stress echocardiography (DSE) in the assessment of functional recovery after revascularization. BACKGROUND: The normal CVIB is blunted by ischemia and recovers early after reperfusion, faster than wall motion improvement. Analysis of CVIB has been widely investigated for its potential to detect viable myocardium in the early stage of infarction. No studies have compared CVIB analysis with other techniques for viability assessment in patients with acute ischemic. Methods and Results: Integrated backscatter images were obtained in 12 patients with AMI on days 1, 3, and 7 after admission and 1 month after revascularization. On day 7, DSE was performed in all patients. On admission, 22 of 144 segments were dyssynergic. On day 1, CVIB was abnormal in all 22 infarcted segments, on day 3, in 16, and on day 7, in only 10 infarcted segments. Eight of 10 segments nonviable by CVIB (CVIB-nonviable) were also nonrespondent by DSE; whereas 12 of 14 segments viable by DSE (DSE-viable) were also CVIB-viable. At follow-up, 10 CVIB-viable segments and 1 CVIB-nonviable segment showed functional recovery; whereas 10 of 14 DSE-viable segments showed functional recovery. Thus the positive predictive value of CVIB and DSE was 83% and 72%, respectively, with a diagnostic agreement between techniques in 77% of segments. CONCLUSIONS: Our data suggest that the normalization in CVIB in the first week after AMI accurately predicts residual tissue viability within the infarct zone. We also observed that the initial pattern of cyclic variation may be predictive of functional recovery. Finally, we found a good correlation between the recovery of a normal CVIB in segments that were still dysfunctional and a more validated method to assess tissue viability, such as the dobutamine test.     

Diltiazem versus nitroglycerin for myocardial protection following coronary artery bypass grafting as assessed by dobutamine stress echocardiography

BACKGROUND: Perioperative infusion of the calcium channel antagonist diltiazem reduces the occurrence and extent of postoperative myocardial ischemia. However, recent reports also mention nitroglycerin as the drug of choice to prevent conduit spasm after coronary bypass grafting. The diagnosis of myocardial ischemia in the perioperative setting is still problematic. Dobutamine stress echocardiography (DSE) is an established technique that combines inotropic stimulation with real-time myocardial imaging and delineates normal and abnormal regional contraction patterns. We assessed the perioperative anti-ischemic effects of diltiazem and nitroglycerin during hemodynamic stress using DSE. METHODS: 50 adult patients were included in a prospective randomized study. Diltiazem or nitroglycerin was used from the onset of extracorporeal circulation until 24 h postoperatively. Dobutamine stress echocardiography was performed in a stepwise fashion 2 to 3 h after elective coronary artery bypass grafting. RESULTS: In 42 of 49 patients, dobutamine stress echocardiography either reached a level of 40 micrograms/kg/min dobutamine or achieved the target heart rate. One patient improved in terms of segmental wall motion abnormalities and three patients developed new abnormalities without corresponding electrocardiographic changes. Analysis of ischemia-sensitive parameters showed lower creatine kinase MB (p = 0.032) and troponin I levels (p = 0.1) in the diltiazem group 24 h postoperatively. Heart rate was significantly lower in the diltiazem group (p = 0.0003). CONCLUSIONS: Under conditions of hemodynamic stress, DSE revealed no significant difference between diltiazem and nitroglycerin with regard to renewed ischemia.     

Bioenergetic abnormalities associated with severe left ventricular hypertrophy.

Transmurally localized 31P-nuclear magnetic resonance spectroscopy (NMR) was used to study the effect of severe pressure overload left ventricular hypertrophy (LVH) on myocardial high energy phosphate content. Studies were performed on 8 normal dogs and 12 dogs with severe left ventricular hypertrophy produced by banding the ascending aorta at 8 wk of age. Spatially localized 31P-NMR spectroscopy provided measurements of the transmural distribution of myocardial ATP, phosphocreatine (CP), and inorganic phosphate (Pi); spectra were calibrated from measurements of ATP content in myocardial biopsies using HPLC. Blood flow was measured with microspheres. In hypertrophied hearts during basal conditions, ATP was decreased by 42%, CP by 58%, and the CP/ATP ratio by 32% in comparison with normal. Increasing myocardial blood flow with adenosine did not correct these abnormalities, indicating that they were not the result of persistent hypoperfusion. Atrial pacing at 200 and 240 beats per min caused no change in high energy phosphate content in normal hearts but resulted in further CP depletion with Pi accumulation in the inner left ventricular layers of the hypertrophied hearts. These changes were correlated with redistribution of blood flow away from the subendocardium in LVH hearts. These findings demonstrate that high energy phosphate levels and the CP/ATP ratio are significantly decreased in severe LVH. These abnormalities are proportional to the degree of hypertrophy but are not the result of persistent abnormalities of myocardial perfusion. In contrast, depletion of CP and accumulation of Pi during tachycardia in LVH are closely related to the pacing-induced perfusion abnormalities and likely reflect subendocardial ischemia.