二硝酸异山梨酯介入99mTc-MIBI心肌显像对梗死后存活心肌的判定及比较

目的:评价二硝酸异山梨酯(Isoket)介入99mTc-甲氧基异丁基异腈(MIBI)心肌断层显像检测心肌梗死后存活心肌的价值,并观察99mTc-MIBI心肌显像评价急性心肌梗死(AMI)与陈旧性心肌梗死(OMI)存活心肌的差异.方法:对16例OMI患者和12例AMI患者,分别进行静息99mTc-MIBI显像和Isoket静脉介入后99mTc-MIBI心肌断层显像.结果:静息99mTc-MIBI显像出现灌注异常185个节段,根据心肌放射性分布情况打分,平均得分为15.1±3.8,Isoket介入99mTc-MIBI显像后出现灌注异常节段为160个,平均得分为10.8±1.6,两者比较差别有显著性(P＜0.01).静息99mTc-MIBI显像出现的185个灌注异常的节段中16例OMI占102个,12例AMI占83个;Isoket介入后87个得到不同程度改善的节段中OMI占40个,AMI占47个,两者比较,P＜0.05.结论:Isoket介入99mTc-MIBI显像与静息99mTc-MIBI显像比较可明显提高对存活心肌检测的灵敏度,并对AMI存活心肌的检出率要明显高于OMI.     

溶栓后联合介入治疗对急性心肌梗死患者心肌组织灌注的影响

目的:探讨溶栓后联合经皮冠状动脉介入治疗(PCI)对急性心肌梗死(AMI)患者心肌组织灌注的影响。方法:采用回顾性分析首次AMI患者94例,发病时间均在12 h以内。36例接受溶栓联合PCI治疗,58例接受直接PCI治疗,并于PCI后测定心肌组织灌注分级,了解二者对AMI患者心肌组织灌注的影响。结果:2组患者自发病至PCI时间比较无明显差异;首次冠状动脉造影显示:溶栓联合PCI组PCI前梗死相关动脉TIMI 3 级血流者明显较直接PCI组增多;溶栓联合PCI组介入治疗成功率高,且术后TIMI 3级血流者、PCI后心肌组织灌注TMP 2级以上者均明显多于直接PCI组;2组比较出血并发症发生率无明显差异。结论:溶栓联合PCI治疗AMI安全有效,早期再通率高,心肌微循环灌注好,心肌梗死面积小,更有利于保护心室功能,且不增加出血并发症。     

99mTc-MIBI心肌灌注显像预测急性心肌梗死患者延迟PCI疗效的临床意义

目的评价^99mTc-MIBI心肌灌注显像在急性心肌梗死（AMI）患者延迟经皮冠状动脉介入治疗（PCI）策略中的意义。方法 55例未行急诊PCI的AMI患者,以术前静息及硝酸甘油介入^99mTc-MIBI心肌灌注显像结果分为有存活心肌组和无存活心肌组,观察两组PCI前后1周静息心肌灌注缺损计分变化及PCI前、PCI后12个月后超声心动图改变。结果有存活心肌组和无存活心肌组静息心肌灌注显像缺损积分PCI前分别为（11.66±0.43）、（12.41±0.64）分,PCI后分别为（7.02±0.56）、（10.09±0.45）分,两组PCI前后心肌血流灌注均有改善（P均<0.05）,有存活心肌组心肌血流灌注改善更显著（P<0.01）。超声心动图检测显示PCI前两组左室射血分数（LVEF）及左室舒张末期内径（LVEDD）比较有统计学差异（P<0.05或<0.01）,PCI后12个月有存活心肌组LVEF、LVEDD改善优于无存活心肌组（P<0.05或<0.01）。结论静息及硝酸甘油介入^99mTc-MIBI心肌灌注显像可作为判断AMI患者延迟PCI疗效的可靠方法。     

选择性冠状动脉99mTc-MIBI介入心肌灌注显像评价心肌梗死后存活心肌的实验研究

目的 探讨选择性冠状动脉99mTc-MIBI介入心肌灌注显像检测心肌梗死后存活心肌的价值。方法 以犬的实验性心肌梗死模型为研究对象,采用自身对照方法,先后行99mTc-MIBI静息心肌灌注显像、硝酸甘油(NTG)静滴99mTc-MIBI。心肌灌注显像和选择性冠状动脉99mTc-MIBI介入心肌灌注显像,采用四点计分法对各节段核素分布进行半定量评价。结果 与NTG静息心肌灌注显像比较,选择性冠状动脉99mTc-MIBI介入心肌灌注显像对心肌梗死后存活心肌有更高的检出率[(5.1±1.5)vs(6.3±1.4)分,P<0.05]。结论 选择性冠状动脉99mTc-MIBI介入心肌灌注显像诊断存活心肌,具有准确、快速、可与冠状动脉造影同步的优点,具有实用价值。     

心肌灌注显像对非ST段抬高的急性冠脉综合征介入治疗心肌再灌注的研究

目的通过心肌灌注断层显像研究急性冠脉综合征(ACS)冠脉介入治疗(PCI)前后心肌再灌注的变化。方法2000-012005-01对中山大学附属第五医院的106例ACS患者用99m锝甲氧基异丁基异腈心肌灌注断层显像测定心肌再灌注后的心肌复活面积情况。结果PCI后心肌显像心肌缺损面积较PCI前缩小,两者相比差异具有显著性[(12·8±4·6)%对(26·7±4·9)%,P<0·05];PCI后冠状动脉造影TIMI血流Ⅲ级者再灌注后心肌缺损面积缩小率明显大于冠状动脉造影TIMI血流≤Ⅱ级者(43·4%对14·6%,P<0·05);PCI后预后不良组心肌缺损面积明显高于预后较好组[(25·81±5·7)%,n=19对(13·6±4·2)%,n=87,P<0·05]。PCI后开通二级以上冠状动脉2支以上血管的心肌缺损面积缩小率明显高于开通1支血管的患者(39·1%,n=31对23·7%,n=71,P<0·05)。结论心肌灌注断层显像可作为ACS无创性心肌再灌注疗效评价较准确的手段。     

急性ST段抬高心肌梗死急诊介入治疗后心肌再灌注不良对近、远期预后的影响

目的 探讨急性心肌梗死急诊经皮冠状动脉介入治疗(PCI)后心肌再灌注状态不良的发生率及其对近、远期临床预后的影响.方法 回顾性收集964例急性ST段抬高心肌梗死(STEMI)行急诊PCI治疗患者的临床资料、冠状动脉造影资料与心电图,以ST段回落程度与心肌梗死溶栓试验心肌灌注(TMP)分级等指标评估心肌再灌注状态.患者分为4组:A组为ST段回落率≥50%并且术后TMP分级为Ⅲ级;B组为ST段回落率<50%并且术后TMP分级为Ⅲ级;C组为ST段回落率≥50%并且术后TMP分级≤Ⅱ级;D组为ST段回落率<50%并且术后TMP分级≤Ⅱ级.以A组代表心肌灌注状态良好者,D组代表心肌灌注状态不良者.分析心肌再灌注不良患者的发生率及其对近远期预后的影响.结果 STEMI急诊PCI术后梗死相关动脉前向血流达到TIMIⅢ级而TMP分级为Ⅱ级以下者占27.3%(237/964),心电图ST段回落小于50%者占30.6%(266/964).11.31%(109/964)的患者发生远端栓塞.A组占总例数的48.9%(425/964),D组占总例数的10.5%(91/964).与A组比较,D组患者在住院期间(RR=64.63,P<0.01)以及随访期间(RR=11.69,P<0.01)均有较高的主要不良心脏事件发生风险.结论 急性心肌梗死急诊PCI后不到50%的患者心肌再灌注良好,心肌再灌注状态与近、远期临床预后显著相关.     

急性心肌梗死经皮冠状动脉介入治疗后心肌灌注的方法评价

目的　联合应用TIMI心肌灌注分级 (TMP)、校正的TIMI画面记帧 (CTFC)、心电图ST段变化 (sumSTR)方法评价急性心肌梗死 (AMI)急诊经皮冠状动脉介入治疗 (PCI)后心肌灌注程度 ,探讨心肌灌注程度对临床预后的影响。方法　 77例AMI患者PCI后即刻采用TMP CTFC、TMP sumSTR、CTFC sumSTR三种联合方法评价心肌灌注程度 ,PCI术后 1个月检查双核素心肌灌注显像 ,记录 6个月心脏事件。结果　评价心肌灌注程度 ,与双核素心肌灌注显像对比 ,TMP sumSTR敏感性 86 7%、特异性 85 7%、准确性 86 2 % ;TMP CTFC敏感性 80 %、特异性 77 1%、准确性 78 5 % ;多变量回归分析TMP 0 / 1级 sumSTR <30 %为 6个月心脏事件的独立危险因子 (OR=2 1 5 ,95 %可信区间 2 7～ 6 5 7,P =0 0 0 3) ;Kaplan Meier分析曲线显示TMP sumSTR方法评价的心肌灌注不良组 6个月心脏事件高于心肌灌注良好组 (P <0 0 5 )。结论　TMP sumSTR、TMP CTFC能更好的评价心肌灌注程度 ;TMP sumSTR可预测 6个月心脏事件。     

老年患者直接冠状动脉介入术后心肌组织灌注的特点及预后分析

目的观察老年急性心肌梗死(AMI)患者接受PCI后的心肌组织水平的灌注特点及预后情况。方法选择因AMI行PCI的患者388例,根据患者年龄分为老年组(≥60岁)187例及中青年组(<60岁)201例。通过观察TIMI心肌灌注(TMP)分级、心肌blush分级(MBG)及术后ST段回落比例,评价2组患者的术后心肌组织灌注及预后。结果中青年组较老年组病变血管数明显降低,梗死相关血管开通时间明显缩短,术后MBG 3级、术后TMP 3级及ST段回落比例及LVEF均明显升高(P<0.05)。结论老年AMI患者冠状动脉病变程度重,PCI术后虽病死率低于中青年,但组织水平灌注和心功能较差,应给予足够的重视。     

心肌声学造影对急性心肌梗死患者经皮冠脉介入术后心肌微循环的影响

目的探讨心肌声学造影对急性心肌梗死(AMI)患者经皮冠脉介入术(PCI)后TIMI血流达Ⅲ级者心肌微循环的影响。方法采用Sequoia512型超声心动仪,应用二次谐波成像和高机械指数超声发射,对30例AMI患者PCI术后进行经静脉声诺维心肌声学造影显像和超声检查。结果共210个节段与梗死相关动脉再灌注有关,灌注正常即心肌造影计分(MCS)1分146段,灌注不良MCS 0.5分53段,无灌注MCS 0分11段。运动正常节段中MCS 1分者明显高于运动异常节段(P<0.05)。根据声学造影记分指数(CSI)将患者分为A组22例(CSI>0.8),B组8例(CSI≤0.8)。A组射血分数(EF)显著大于B组(P<0.05)。结论TIMIⅢ级血流并非再灌注成功的金标准。心肌微循环与心室收缩功能有一定相关性,微循环良好的患者EF值大于微循环较差者。经静脉声诺维心肌声学造影是一种安全无创的检测手段,是反映心肌微循环灌注的有效方法。     

直接经皮冠状动脉腔内成形术中冠状动脉内心电图判定存活心肌的价值

目的 应用99mTc-MIBI心肌断层显像(SPECT)评价冠状动脉内心电图(IC-ECG)判定急性心肌梗死(AMI)存活心肌的价值。方法 56例急性前壁心肌梗死患者，接受了直接经皮冠状动脉腔内成形术(PTCA)，梗死相关动脉前降支(LAD)达到TIMI3级血流后IC-ECG自PTCA导引导丝尾端引出作为参照基线，在进一步球囊扩张时IC-ECG ST段再次抬高大于0．2mV时认为具有判定梗死相关部位有存活心肌的意义。测定并比较急性期及恢复期左心室梗死相关区域节段性缩短率(LVSS)与射血分数(LVEF)，梗死区域存活心肌通过恢复早期静息与硝酸甘油介入两次99mTc-MIBI SPECT量化判定。结果 4l例病人(A组)行直接PTCA时IC-ECG ST段明显抬高，15例(B组)未出现相应变化，A组INSS、INEF。在恢复期均显著大于B组，两次99mTc-MIBISPECT显示，硝酸甘油介入后显像A组梗死缺损区面积明显减少，核素放射性计数百分比亦明显增加，B组则无明显改变，说明A组梗死区域有较多存活心肌，与IC-ECT ST段抬高意义一致。结论 直接PTCA过程中可通过球囊扩张时IC-ECG ST段抬高变化初步判定梗死相关区域的心肌活性。     

Assessment of myocardial blood flow and volume using myocardial contrast echocardiography

The development of new microbubble agents and ultrasound imaging modalities now allows the assessment of myocardial perfusion with echocardiography. Microbubbles also can be administered intravenously as constant infusions, which allows their concentration in blood to reach steady state. If the relation between microbubble concentration and video intensity is within the linear range, then myocardial video intensity will reflect the concentration of microbubbles in that region, which at steady state is the myocardial blood volume. The ability to destroy microbubbles and measure their replenishment into the ultrasound beam provides an opportunity to evaluate microbubble (or red blood cell) velocity. The product of myocardial blood volume and red blood cell velocity represents myocardial blood flow.     

Detection of resting myocardial perfusion defects by SonoVue myocardial contrast echocardiography

BACKGROUND: SonoVue is a new microbubble contrast agent containing sulfur hexafluoride. We assessed the efficacy of SonoVue myocardial contrast echocardiography (MCE) to detect resting perfusion abnormalities. Methods: Nineteen adult patients with a wall motion abnormality in a screening echocardiogram were studied. Each patient received up to four bolus injections of 2.0 mL SonoVue (Bracco Diagnostics, Inc.) during echocardiographic examination using either B-mode(n = 12)or power Doppler(n = 7)imaging. Each patient also had SPECT nuclear perfusion imaging performed. Segmental assessment of myocardial perfusion from SonoVue MCE images were compared with corresponding SPECT nuclear images. RESULTS: Using B-mode imaging, the mean number of views obtained with a single SonoVue injection ranged from 1.4 to 1.9, with 2 or 3 injections required for a complete examination. Ninety-four percent of segments were scored as diagnostic. Agreement between B-mode and SPECT images was 72% for segments with a perfusion defect, 86% for normal perfusion, and 80% for segments with either perfusion defect or normal perfusion (all views combined). Using power Doppler imaging, the mean number of views obtained with a single SonoVue injection ranged from 1.0 to 1.3, with 2 to 4 injections required for a complete examination. Sixty-eight percent of segments were scored as diagnostic. Agreement between power Doppler and SPECT images was 67% for perfusion defects, 53% for segments with normal perfusion, and 59% for segments with either perfusion defect or normal perfusion (all views combined). CONCLUSIONS: SonoVue MCE has the potential to assess myocardial perfusion at rest. B-mode imaging was more accurate than power Doppler imaging when compared with SPECT nuclear imaging.     

CTRP9在心肌梗死后心肌重构中的作用研究进展

心肌梗死后的心肌重构是一个复杂的病理过程,严重影响患者预后。CTRP9是近年来新发现的脂肪因子,大量研究表明CTRP9可抑制心肌梗死后心肌重构,本文就CTRP9对心肌梗死后心肌重构的相关研究作一综述。     

Stent implantation at the site of the myocardial bridge after myocardial infarction. Long-term results

Although myocardial bridge is asymptomatic in most patients, it can lead to myocardial ischemia, myocardial infarction, cardiac arrhythmias, and sudden death. The authors report the case of a symptomatic myocardial bridge treated by classical stenting of the mid left anterior descending artery. The outcome was good. A control coronary angiography performed 36 months later showed no significant restenosis. No recurrence of angina during five years follow-up was observed. (Int J Cardiovasc Intervent 2004; 6: 148-150)     

Assessment of regional myocardial blood flow with myocardial contrast echocardiography: an experimental study

OBJECTIVES: The aim of this study was to verify the accuracy of using myocardial contrast echocardiography (MCE), to quantify regional myocardial blood flow (MBF), and to evaluate myocardial viability in comparison to that measured by radiolabeled microsphere and pathologic examination. METHODS: Epicardial MCE was obtained in five myocardial ischemic dogs with constant microbubble intravenous infusion. After the video intensity (VI, y) versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: y = A(1 - e(-beta t)), the MBF was calculated as the product of A (microvascular cross-sectional area or myocardial blood volume) and beta (mean myocardial microbubble velocity). The MBF was also obtained by radiolabeled microsphere method. RESULTS: The MBF derived by radiolabeled microsphere method in the normal, ischemic, and infarcted region was 1.5 +/- 0.3, 0.7 +/- 0.3, and 0.3 +/- 0.2 ml/min per gram, respectively; P < 0.01. The product of A and beta in those regions was 52.5 +/- 15.1, 24.4 +/- 3.9, and 3.7 +/- 3.8, respectively; P < 0.01. The normalized product of A and beta correlated well with normalized MBF (r = 0.81, P = 0.001). CONCLUSION: Our initial study demonstrated that MCE has an ability to assess MBF in ischemic myocardium in the experimental model. It may provide a potential capability to detect viable myocardium noninvasively after total persistent coronary occlusion in the clinical setting.     

Multislice MR perfusion imaging and regional myocardial function analysis: complimentary findings in chronic myocardial ischemia

Purpose: The purpose of this study is to assess the reliability of multislice MR perfusion imaging in comparison to regional wall function and nuclear medicine and to test different qualitative and quantitative parameters for perfusion assessment. Material and methods: 15 patients with chronic myocardial ischemia underwent CINE and first-pass perfusion MR imaging. Functional myocardial imaging was performed using a segmented CINE FLASH sequence and systolic myocardial wall thickening was assessed after semiautomated segmentation. MR first-pass perfusion studies were performed using a multislice saturation recovery TurboFLASH sequence. Different parameters were calculated for assessment of hypoperfused segments and results of MR imaging compared to ^99mTc-SestaMIBI SPECT. Results: MR perfusion imaging showed a sensitivity of 72% and a specificity of 98%. In combination with MR CINE imaging and wall thickening analysis we calculated a sensitivity of 100% and a specificity of 93%. Qualitative and quantitative perfusion parameter analysis showed significant differences between normal and hypoperfused segments for the signal intensity increase (p < 0.001), the signal intensity upslope (p < 0.001) as well as for the myocardial mean transit time (p < 0.001). Conclusion: The combination of systolic wall thickening analysis and myocardial perfusion can markedly improve the sensitivity of MRI in depiction of LV myocardial perfusion abnormalities. For assessment of hypoperfusion, different quantitative and qualitative parameters can be calculated showing significant differences between normal state and hypoperfusion.     

应用实时心肌超声造影定量评价心功能对急性心肌梗死犬心肌血流量的影响

目的:探讨心功能对心肌梗死犬心肌血流灌注的影响。方法:18只健康杂种犬于前降支分出的第1对角支远端约1cm处结扎3h,应用心肌超声造影(MCE)定量分析左室前壁中间段和下壁中间段心肌血流量(MBF)。结果:17只犬成功建立急性心肌梗死模型。根据结扎3h后左室整体射血分数(EF)分为2组:A组(EF≥50%)7只,B组(EF<50%)10只。B组左室前壁中间段和下壁中间段MBF均低于A组,但2组之间差异无统计学意义;与结扎前相比,2组左室前壁中间段MBF均明显降低,差异有统计学意义(P<0.05),A组左室下壁中间段MBF略升高,B组则降低,但均差异无统计学意义。结论:心功能对MBF有一定的影响,可能会低估冠状动脉血流储备和高估狭窄程度,在以MCE诊断冠心病时应注意心功能对MBF的影响。     

Assessment of myocardial viability with myocardial contrast echocardiography

The application of noninvasive imaging techniques to assess myocardial viability has become an important part of routine management of patients with acute myocardial infarction and chronic coronary artery disease. Information regarding the presence and extent of viability may help identify patients likely to benefit from revascularization or therapy directed at attenuating left ventricular remodeling. Myocardial contrast echocardiography (MCE) is capable of defining the presence and extent of viability by providing an accurate assessment of microvascular integrity needed to maintain myocellular viability. It is especially suited for the spatial assessment of perfusion, even when myocardial blood flow is reduced substantially in the presence of severe epicardial stenoses or in a bed dependent on collateral perfusion. The routine use of MCE to evaluate viability in patients with acute and chronic coronary artery disease is now feasible with the advent of new imaging technologies and microbubble agents capable of myocardial opacification from venous injections. The utility of this technique for determining treatment strategies has not been established but is forthcoming.     

达格列净对急性心肌梗死后大鼠的心肌电活动影响的研究

目的探讨达格列净对急性心肌梗死(acute myocardial infarction,AMI)后大鼠心室结构及心室肌电活动稳定性的影响。方法将健康成年Sprague-Dawley(SD)雄性大鼠24只随机分为三组:正常对照组(NC组,8只)、安慰剂组(PB组,8只)达格列净组(DAPA组,8只)。NC组、PB组给予1 ml·kg^-1·d^-1生理盐水灌胃处理,DAPA组给予1 ml·kg^-1·d^-1达格列净灌胃处理,一天一次。给药14天后,三组大鼠经外科开胸手术,剪开心包,NC组只观察,PB组和DAPA组通过结扎前降支动脉制备AMI模型,建模成功后即行超声心动图测量左心室舒张末期内径(left ventricular end diastolic dimension,LVEDD)、左心室收缩末期内径(left ventricular end-systolic diameter,LVESD)和左心室射血分数(left ventricular ejection fraction,LVEF);通过SiS2程序性刺激评估三组大鼠左心室有效不应期(1eft ventricular effective refractory period,LVERP)、SiS连续刺激测定心室颤动阈值(ventricular fibrllation threshold,VFT);利用Masson染色检测左心室心肌纤维化程度。结果分析比较三组小鼠心动超声各指标变化情况:①LVERP:PB组、DAPA组较NC组明显缩短[PB组比NC组(9.13±1.04)ms比(17.86±2.03)ms,P<0.01;DAPA组比NC组(14.37±1.25)ms比(17.86±2.03)ms,P<0.01];然而DAPA组较PB组增加[(14.37±1.25)ms比(9.13±1.04)ms,P<0.01]。②VFT:PB、DAPA组的VFT较NC组均明显降低[PB组比NC组(2.88±1.29)V比(10.07±0.98)V,P<0.01;DAPA组比NC组(7.44±1.03)V比(2.88±1.29)V,P<0.01]。③LVEDD:PB组LVEDD较NC组明显增加[(10.00±1.12)mm比(6.10±1.79)mm,P<0.05];DAPA组LVEDD较PB组明显降低[(7.98±0.97)mm比(10.00±1.12)mm,P<0.05]。④LVESD:PB组、DAPA组LVESD均较NC组增加[PB组比NC组(8.01±0.76)mm比(3.25±1.82)mm,P<0.05;DAPA组比NC组(5.94±0.82)mm比(3.25±1.82)mm,P<0.05];DAPA组LVESD较PB组明显降低[(5.94±0.82)mm比(8.01±0.76)mm,P<0.05]。⑤LVEF:PB组、DAPA组LVEF均较NC组显著下降[PB组比NC组(23.92±2.04)%比(49.75±2.07)%,P<0.05;DAPA组比NC组(35.85±2.15)%比(49.75±2.07)%,P<0.05];进一步比较发现,DAPA组较PB组增加[(35.85±2.15)%比(23.92±2.04)%,P<0.05]。⑥左心室心肌纤维化程度:PB组、DAPA组左心室心肌纤维化程度均较NC组增加[PB组比NC组(45.69±3.19)%比(30.07±2.19)%,P<0.05;DAPA组比NC组(35.13±2.17)%比(30.07±2.19)%,P<0.05];进一步比较发现,DAPA组较PB组明显减小[(35.13±2.17)%比(45.69±3.19)%,P<0.05]。结论达格列净可以增加AMI大鼠左心室的电活动稳定性,降低左心室纤维化,改善心室重塑。     

Effect of nifedipine on the myocardial and vascular response to myocardial ischemia

Summary Nifedipine reduces reactive hyperemia following brief coronary artery occlusions. To determine whether this is related to improvement in collateral blood flow to ischemic myocardium or alterations in myocardial oxygen consumption, ten chloralose anesthetized dogs were instrumented with coronary sinus catheters, circumflex artery flowmeters, and ultrasonic microcrystals for measurement of myocardial segment shortening. Myocardial oxygen consumption and circumflex coronary artery flow were determined at rest and during incremental infusions of isoproterenol. Myocardial blood flow measured with microspheres and segmental function were assessed during and following 30- and 60-second coronary artery occlusions. Thirty minutes after the intravenous administration of nifedipine, 10 g/kg iv, all measurements were repeated. Nifedipine did not alter myocardial oxygen consumption or the relationship between oxygen consumption and circumflex coronary artery flow either at rest or during isoproterenol infusion. Following 60-second coronary occlusions, nifedipine reduced peak circumflex coronary artery flow (176±99 vs. 128±68 cc/min) and reactive hyperemia debt repayment (221±84 vs. 158±66%; p<0.01). Nifedipine did not alter flow to ischemic segments during coronary artery occlusions (0.16±0.10 vs. 0.19±0.13 ml/min/g mean transmural flow). Furthermore, nifedipine did not affect the severity of ischemic segment dysfunction, nor the rate of recovery of ischemic segment function following release of coronary artery occlusion. We conclude that the reduction in reactive hyperemia induced by nifedipine was not related to alterations in the severity of hypoperfusion in ischemic areas, or alterations in myocardial oxygen consumption. Reductions in reactive hyperemia produced by nifedipine did not impair recovery of mechanical function in postischemic myocardium.This study was supported in part by grants HL01162 and HL20598 from the National Heart, Lung and Blood Institute of the National Institutes of Health, Bethesda, Maryland; and by a grant-in-aid from the American Heart Association, Minnesota Affiliate, Inc. Dr. Homans was a fellow of the American Heart Association, Minnesota Affiliate, and recipient of National Research Service Award (HL06575) from the National Heart, Lung and Blood Institute of the National Institute of Health at the time that this work was performed.