Changes of coronary blood flow in vasospastic angina under cold stimulation by transthoracic Doppler echocardiography

This study was done to evaluate changes of microvascular function under cold stimulation by measuring coronary flow velocities (CFVs) in vasospastic angina (VA) patients using transthoracic Doppler echocardiography (TTDE). 14 patients with VA and 15 healthy controls were included. CFVs were measured at the distal left anterior descending coronary artery by TTDE at baseline and under cold stimulation. Hyperemia was induced by intravenous adenosine infusion (140 microg/kg/min). At baseline, CFVs and coronary flow reserve (CFR) were not different between controls and VA patients. Under cold stimulation, the degree of increment of CFV with adenosine was lower in VA patients than in controls. Comparing baseline with cold stimulation, coronary flow reserve (CFR) increased (3.1+/-0.7 to 3.8 +/-1.0, p=0.06) in controls. In contrast, in VA patients, CFR was decreased (2.8 +/-0.9 to 2.6 +/-0.7, p=0.05) and coronary vascular resistance index markedly increased (0.35 to 0.43, p=0.01). Throughout the study, no patient experienced chest pain or ECG changes. In VA patients, CFR was preserved at baseline, but coronary blood flow increase in response to cold stimulation was blunted and CFR was decreased. These findings suggest that endothelial dependent vasodilation is impaired at the coronary microvascular and the epicardial artery level in VA under cold stimulation.     

川崎病患儿冠状动脉血流储备测定与影像形态学诊断的对照研究

目的评价持续冠状动脉病变对川崎病（KD）患儿冠状动脉血液动力学的影响,探讨冠状动脉血流储备（CFR）检测在KD患儿冠状动脉病变远期随访中的应用价值。方法选择因胸痛、心悸以及各类偶发早搏的患儿为对照组,KD并发持续左冠状动脉病变患儿为KD组,均予以ATP160μg·kg^-1·min^-1持续静脉注射,共6min。运用经胸多普勒超声心动图（TTDE）检测冠状动脉左前降支（LAD）在ATP注射前后的舒张期峰值流速（PDV）及平均流速（MDV）,并通过计算比值得出相应CFR（PDV）和CFR（MDV）值。结果对照组纳入25例,CFR（PDV）和CFR（MDV）值均与年龄呈显著正相关（r=0.596,0.591,P=0.002,0.002）;〈2岁、-8岁和〉8岁组的CFR（PDV）95%参考值范围分别为≥1.22、≥1.94和≥2.22。KD组纳入8例,静息状态下PDV和MDV值分别为（50.0±15.07）cm.s^-1和（35.16±11.52）cm.s^-1,显著高于对照组（P=0.004,0.015）;而CFR（PDV）和CFR（MDV）值明显降低,分别为（1.67±0.38）cm.s^-1和（1.69±0.47）cm.s^-1（P=0.002,0.018）。与对照组比较,KD组7/8例（87.5%）患儿CFR（PDV）值显著降低。结论持续冠状动脉病变可导致KD患儿CFR值显著降低,TTDE检测患儿CFR具无创、安全和便捷的优点,对于KD冠状动脉病变的长期随访与临床诊断治疗策略的选择具有指导意义。     

Coronary flow reserve: measurement with transthoracic Doppler echocardiography is reproducible and comparable with positron emission tomography.

Detection of early vascular changes indicated by lowered coronary flow reserve (CFR) would allow early treatment and prevention of atherosclerosis. The purpose of this study was to test whether it is possible to reproducibly measure CFR with transthoracic Doppler echocardiography (TTE) in healthy volunteers. We measured CFR using dipyridamole infusion in ten healthy male volunteers with two methods: TTE and positron emission tomography (PET) with oxygen-15-labelled water (group A). However, CFR was assessed twice with TTE in eight healthy male volunteers (group B) to study the reproducibility of this method. We compared CFRs obtained using TTE flow measurements in the left anterior descending coronary artery (LAD) and PET flow measurements in the corresponding myocardial area. Coronary flow in LAD could be measured in all subjects using TTE. By TTE, an average CFR based on peak diastolic flow velocity (PDV) was 2.72 +/- 1.16, mean diastolic flow velocity (MDV) 2.56 +/- 1.06 and velocity time integral (VTI) 1.87 +/- 0.49. The results were reproducible in two repeated TTE studies (coefficient of variation in MDV 6.1 +/- 4.3%, n=8). By PET, CFR was 2.52 +/- 0.84. CFR assessed by TTE correlated closely with that measured by PET (MDV r=0.942, P<0.001; PDV r=0.912, P<0.002 and VTI r=0.888, P<0.006) and intraclass correlation was 0.929 (MDV) and tolerance limits for differences of CFRs was -0.78 to 0.72. We show that CFR measured by TTE has an excellent correlation with CFR measured by PET. We also found that TTE measurements of CFR were highly reproducible.     

Nearly automated analysis of coronary Doppler flow velocity from transthoracic ultrasound images: validation with manual tracings

Coronary flow velocity reserve is obtained by manual tracings of transthoracic coronary Doppler flow velocity profiles as the ratio of stress versus baseline diastolic peak velocities. This approach introduces subjectivity in the measurements and limits the information which could be exploited from the Doppler velocity profile. Accordingly, our goals were to develop a technique for nearly automated detection of Doppler coronary flow velocity profile, and automatically compute both conventional and additional amplitude, derivative and temporal parameters, and validate it with manual tracings. A total of 100 patients (17 normals, 15 patients with severe coronary stenosis, 41 with connective tissue disease and 27 with diabetes mellitus) were studied. Linear correlation and Bland–Altman analyses showed that the proposed method was highly accurate and repeatable compared to the manual measurements. Comparison between groups evidenced significant differences in some of the automated parameters, thus representing potentially additional indices useful for the noninvasive diagnosis of microcirculatory or coronary artery disease.     

冠脉造影数字跟踪法测定冠脉血流速度与Doppler血流速度相关分析

目的研究冠脉造影数字跟踪技术测定冠脉血流速度与Doppler血流速度之间的相关性。方法入选住院冠脉造影病人40例,包括左前降支(LAD)单支病变行介入治疗(PCI)10例,诊断性冠脉造影30例(冠脉造影正常、心肌桥、轻-中度狭窄病变)。所有病例采用冠脉造影数字跟踪技术测定LAD平均血流速度(CFVm),其中15例用冠脉造影TIMI计帧法测定LAD血流速度(帧.f)。另15例使用Doppler导丝测定LAD平均峰值血流速度(APV),并与CFVm作相关分析。结果冠脉造影数字跟踪法测定LAD的CFVm(18.58±6.46)与Doppler导丝测得的LAD近端(17.42±5.99)和远端(17.93±5.78)的APV显著相关(r=0.79.r=0.64);而与TIMI计帧法血流速度呈弱相关(r=-0.47)。PCI治疗成功后,随着狭窄最小腔径增加,跟踪法血流速度加快(P<0.01),CFVm≥20cm/s。结论冠脉造影数字跟踪技术测定冠脉血流速度与Doppler血流速度显著相关,两者表达单位一致,方法简便易行,重复性好,可以用作常规冠脉造影血流速度定量指标。     

Coronary hemodynamics during hemopump left-intraventricular assistance.

Hemopump left intraventricular pumping (HP) can permit percutaneous transluminal angioplasty (PTCA) in high-risk patients. Benefits may be related to left ventricular unloading or myocardial perfusion improvement, or both. Direct ultrasonic measurements of coronary blood flow were made in the dilated vessel after a successful PTCA in five patients. A 3 Fr intracoronary Doppler catheter was placed in the coronary artery to measure flow velocities (maximal or diastolic velocity; minimum or systolic velocity and mean velocity). A SwanGanz catheter was used to measure the cardiac index and pulmonary capillary wedge pressure. Mean aortic pressures were monitored through an 8 Fr guiding catheter. Measurements were made after a 5-min period of minimal speed (T0) of the HP to avoid retrograde regurgitation through the turbine; during the increase from minimum to maximal speed (T1); after a 5-min period of maximal HP flow (3l/min) (T2) and after HP was pulled back (T3). From T0 to T2, cardiac index rose from 1.93 +/- 0.38 to 3.26 +/- 0.35 l/min/m2 and capillary wedge pressure decreased from 18 +/- 6 to 13 +/- 5 mmHg (p less than 0.05); from T2 to T3, cardiac index decreased to 2.4 +/- 0.4 while capillary wedge pressure increased to 17 +/- 5 (p less than 0.05). Mean arterial pressure and heart rate did not change significantly throughout the study. When the hemopump flow was raised to high speed, coronary blood flow increased immediately but returned shortly to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Technical achievement: transthoracic Doppler echocardiography can be used to detect LAD restenosis after coronary angioplasty.

We investigated the capability of transthoracic Doppler echocardiography (TTE) to detect and quantify the severity of restenosis in the left anterior descending coronary artery (LAD) after percutaneous transluminal coronary angioplasty (PTCA). We studied 10 consecutive patients assigned for quantitative coronary angiography (qCA) due to a recurrent angina pectoris after PTCA of the LAD. The LAD was visualized by TTE, and the presence of local turbulence and an increase in the blood flow velocity was regarded to indicate coronary stenosis. To assess the severity of the stenosis, the increase of blood flow velocity was measured. Angiography showed stenoses of various degrees (27-100%) in all patients. All stenoses were detectable using TTE. Moreover, the ratio of maximal blood flow velocity at the site of stenosis to the pre-stenotic blood flow velocity (M/P-ratio) correlated significantly with the reduction of the luminal diameter of LAD (r = 0.85, P < 0.003). A M/P-ratio higher than 3.0 predicted a diameter reduction of 50% or higher with sensitivity and specificity of 100% in patients with a subtotal stenosis (n = 9). Our results indicate that stenoses in the LAD could be found and the severity of the stenoses could be quantified reliably with TTE. This approach is totally non-invasive and less expensive than coronary angiography and can be used clinically in clarifying restenosis after coronary angioplasty.     

Practical assessment using transmitral Doppler echocardiography for the evaluation of left ventricular filling pressure in patients with systolic ventricular dysfunction

Transmitral flow velocity profiles by Doppler echocardiography are strongly related to left ventricular diastolic properties. The aim of this study was to address the assessment of left ventricular filling pressures by transmitral flow velocity curves in patients with impaired systolic function. 90 patients (23 female, 67 men, age 60.0 +/- 9,9 a) with an ejection fraction < or = 45% either due to coronary artery disease (n = 67) or dilated cardiomyopathy (n = 23) were investigated by Doppler echocardiography prior to left heart catheterization. Early diastolic deceleration time (DT) and ratio of early to late diastolic peak velocities (VE/VA) were measured. Both, DT and VE/VA showed a significant correlation to left ventricular enddiastolic pressures (r = -0.79 respectively r = 0.73, p < 0.001 for all). According to DT three different transmitral flow patterns were identified. All patients with restrictive filling patterns (DT < 160) had elevated left ventricular filling pressures, whereas impaired relaxation (DT > 210) was a strong predictor of normal filling pressures. In patients with pseudonormal transmitral flow patterns (DT 160 to 210) filling pressures could not be predicted. Furthermore DT was strongly related to clinical signs of left heart failure. Doppler echocardiography gives useful additional information on left ventricular filling pressures in patients with systolic dysfunction.     

Doppler continuous-wave analysis of grafted mammary artery as a non-invasive technique for static and dynamic assessment of coronary flow in man

Summary In this paper, Doppler continuous-wave analysis of blood velocity in the internal mammary artery, anastomosed to the left coronary vascular bed in humans who have undergone myocardial revascularization, is proposed as a non-invasive technique to study coronary blood flow during physiological procedures which cause it to change. Blood velocity curves obtained in normal and anastomosed internal mammary arteries were compared during hyperventilation and the Valsalva manoeuvre. During hyperventilation, blood velocity increased in the normal mammary but not in the anastomosed artery. During the expiratory effort of the Valsalva manoeuvre, the mean blood velocity decreased in the normal mammary artery but it did not change significantly in the anastomosed artery. Variations in the mean velocity were largely prevented by simultaneous and well-balanced increases and decreases in the diastolic and systolic velocities, respectively.     

Adenosine infusion to patients with ischaemic heart disease may provoke left ventricular dysfunction detected by echocardiography

Infusion of the endogenous vasodilator adenosine to patients with ischaemic heart disease (IHD) frequently provokes myocardial ischaemia, possibly caused by a coronary steal. The aim of this study was to detect the occurrence and incidence of disturbances in left ventricular (LV) wall motion and Doppler indices of altered LV function during infusion of adenosine. Thirty-seven patients (six female) aged 37-74 years with IHD, verified by coronary angiography, were given up to 200 micrograms kg-1 min-1 (mean 155 +/- 5) adenosine i.v. for 18 +/- 1 min. LV wall motion was monitored by two-dimensional echocardiography (2D-echo). Doppler spectral signal was obtained from the mitral blood flow. All but six of the patients experienced angina pectoris of habitual character in connection with the adenosine infusion. Heart rate increased by 22 +/- 1 beats min-1, systolic blood pressure was unchanged, but diastolic blood pressure decreased slightly. 2D-echo revealed severe regional LV wall motion disturbances already in the basal state in 17 patients. During infusion of adenosine, these abnormalities were aggravated and disturbances also occurred in another 15 patients. Thus, adenosine increased the sensitivity for IHD in this selected material from 49 to 89%. In all, the mean index of wall motion abnormalities increased from 5.1 +/- 1.1 to 10.1 +/- 1.4 (P less than 0.001). The diastolic LV filling characteristics, as evaluated by the Doppler A/E ratios, were of limited value for determination of IHD grade. It is concluded that infusion of adenosine to patients with IHD frequently elicits myocardial ischaemia with disturbances in LV function, and offers an alternative to exercise for stress echocardiography.     

Use of vascular Doppler ultrasound to detect acute estradiol vascular effect in postmenopausal women

OBJECTIVES: To report on a simple practical test for assessing acute estradiol vascular effects on healthy and unhealthy postmenopausal women. INTRODUCTION: Estradiol acts in the endothelium to promote vasodilatation through genomic and non-genomic mechanisms, but its vascular action may be impaired in diabetes mellitus, hypertension, smoking and obesity. METHODS: Nineteen postmenopausal women (nine healthy and 10 with two or more of the above factors) of similar age and time since menopause were examined with vascular Doppler ultrasound. Resistance indexes and systolic and diastolic flow velocities were determined for the brachial and internal carotid arteries at baseline and 20 minutes after administration of a nasal estradiol formulation, available on the market, which reaches 1,200-1,500 pg/ml in the serum in 10-30 minutes. Estradiol blood levels were measured at 30 minutes. RESULTS: The carotid resistance index increased 14.2% (vasoconstriction) in the unhealthy group after estradiol, from a mean +/- S.E. of 0.56 +/- 0.016 at baseline to 0.64 +/- 0.05 (p=0.033), and remained unchanged in healthy women. Brachial diastolic flow velocity increased 19.7% (vasodilatation) in healthy women, from 16.2 +/- 1.93 to 19.4 +/- 0.64 cm/s (p=0.046), and did not change in the unhealthy subjects. Estradiol levels were similar in both groups. DISCUSSION: Healthy postmenopausal women showed brachial vasodilatation while unhealthy postmenopausal women displayed vasoconstriction at the carotid artery. Vascular responses to estradiol were divergent between the groups. CONCLUSIONS: The acute estradiol test, coupled with Doppler ultrasound, seemed to be able to differentiate women with normal and abnormal endothelial function in a simple, non-invasive manner.     

Comparison of blood velocity measurements between ultrasound Doppler and accelerated phase-contrast MR angiography in small arteries with disturbed flow

Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broadening errors by applying a previously published algorithm. The method was tested in a canine aneurysm model by determining velocities in small arteries (3-4 mm diameter) near the aneurysm where there was moderately disturbed flow. Doppler results were compared to velocity measurements in the same arteries acquired with a rapid volumetric phase contrast MR angiography technique named phase contrast vastly undersampled isotropic projection reconstruction magnetic resonance angiography (PC-VIPR MRA). After correcting for intrinsic spectral broadening, there was a high degree of correlation between velocities obtained by the real-time UD and the accelerated PC-MRA technique. The peak systolic velocity yielded a linear correlation coefficient of r = 0.83, end diastolic velocity resulted in r = 0.81, and temporally averaged mean velocity resulted in r = 0.76. The overall velocity waveforms obtained by the two techniques were also highly correlated (r = 0.89 ± 0.06). There were, however, only weak correlations for the pulsatility index (PI: 0.25) and resistive index (RI: 0.14) derived from the two techniques. Results demonstrate that to avoid overestimations of peak systolic velocities, the results for UD must be carefully corrected to compensate for errors caused by intrinsic spectral broadening.     

Transthoracic measurement of left coronary artery flow reserve improves the diagnostic value of routine dipyridamole-atropine stress echocardiogram

Introduction

We hypothesized that coronary flow reserve (CFR) in the left anterior descending artery (LAD) can be effectively measured during an accelerated dipyridamole-atropine stress echocardiography (DASE) protocol to improve the diagnostic performance of the test.

Material and methods

In 64 patients with suspected or known coronary artery disease scheduled for coronary angiography DASE with concomitant CFR measurement in LAD was performed.

Results

Coronary flow reserve measurement and calculation were feasible in 83% of patients. The positive predictive value of undetectable LAD flow was 81% for severe LAD disease. Measured values of CFR were in the range 1.3–4.1 (mean: 2.2 ±0.7). Significantly lower CFR was found in patients with LAD disease (1.97 ±0.62 vs. 2.55 ±0.57, p = 0.0015). The optimal cutoff for detecting ≥ 50% stenosis was CFR ≤ 2.1 (ROC AUC 0.776), corresponding with 68% sensitivity and 84% specificity. In patients with negative DASE results 67% of patients with LAD disease had abnormal CFR, whereas in patients with a positive DASE result 92% of patients with normal LAD had normal CFR. The DASE diagnostic accuracy for the detection of coronary artery disease (CAD) increased from 75% to 85% when CFR measurement was added to wall motion abnormality (WMA) analysis. No test with both abnormalities was false positive for the detection of coronary disease.

Conclusions

Incorporation of CFR measurement into WMA-based stress echocardiography is feasible even in an accelerated DASE protocol and can be translated into an approximate gain of 10% in overall test accuracy.     

The role of echocardiographic techniques in connective tissue diseases

Connective tissue diseases (CTD) lead to a high prevalence of common cardiac manifestations (pericarditis and myocarditis) and of ischemic coronary events with a considerable increase in cardiac mortality related to premature atherosclerosis. Although there are several techniques able to detect cardiac involvement in CTD patients, the most useful and non-invasive technique is echocardiographic exam which is able to detect not only valvular abnormalities, pericardial diseases and pulmonary hypertension but also left ventricular (LV) systolic or diastolic (regional or global) wall motion dysfunction. It is also well known that transesophageal echocardiography (TEE) can better identify cardiac abnormalities, vegetations and embolic sources. Symptomatic patients with positive stress echocardiographic exam or dipyridamole thallium imaging test should be referred for possible cardiac catheterization, especially if a large ischemic territory is involved. Until now, the echocardiographic evaluation of coronary artery tree consisted of assessing regional and global left ventricular systolic and diastolic function at rest and during pharmacological stress test. Recently, a new echocardiographic noninvasive method that allows direct assessment of coronary flow velocity in the mid-distal portion of left anterior descending artery (LAD) has been developed and validated. Advanced ultrasound technology (high-frequency broadband transducer with second harmonic capability) has now made possible a direct arterial visualization and measurement of coronary artery flow in left anterior descending in CTD patients with the assessment of coronary flow reserve (CFR).     

Impaired flow-mediated vasodilation of epicardial coronary artery in vasospastic angina.

To evaluate whether the flow-mediated vasodilation and coronary flow reserve are impaired or not in patients with vasospastic angina (VA), we measured the changes of epicardial coronary artery diameter and flow reserve in spasm related-left anterior descending coronary artery (LAD). The flow mediated-response of epicardial coronary arteries in 15 VA were compared with 15 controls. Using quantitative coronary angiography, we measured the diameter of proximal (pLAD) and middle segment (mid-LAD) of LAD under baseline conditions, during increased blood flow after distal adenosine injection and after proximal administration of nitroglycerin. An increased fraction of average peak velocity after injection of adenosine was similar in both groups [control 340 (mean)+/-24 (SEM)%; VA 330+/-19%]. Flow-mediated vasodilation was preserved in all controls (pLAD 13.1+/-1.4%; mid-LAD 15.8+/-2.5%) but it was significantly impaired in patients with VA (pLAD -1.0+/-1.8%; mid-LAD 0.1+/-3.5%). The vasodilator response to nitroglycerin was comparable in controls (pLAD 25.8+/-2.8%; mid-LAD 27.2+/-2.8%) and VA (pLAD 26.2+/-5.2%; mid-LAD 26.7+/-3.5%). Coronary flow reserve is preserved in patients with VA. However, the flow-mediated response of spasm related-epicardial coronary artery is impaired. This may play an important role in the pathogenesis of coronary artery spasm.     

Characterizing Vortex Ring Behavior During Ventricular Filling with Doppler Echocardiography: An in Vitro Study

Doppler ultrasound color M-mode imaging (CMM) has been proposed as a noninvasive means of quantifying diastolic function by measuring flow propagation into the left ventricle. However, the relationship between CMM-derived parameters and underlying fluid dynamics is still unclear. The purpose of this study was to couple high-resolution velocimetry measurements with ultrasound Doppler and CMM measurements in order to shed light on the relationship between CMM flow propagation and inflow dynamics using a simple yet highly reproducible in vitro model of left ventricular inflow. Two Reynolds number conditions were analyzed: 4000 and 6000. Both conditions produced starting jets that formed vortex rings. Average (N = 5) CMM centerline velocities were in agreement with DPIV centerline velocities, although large uncertainty in CMM data was present (uncertainty +/- 10 cm s(-1)). Two flow propagation parameters were extracted from the CMM data: the first utilized an isovelocity as the marker of flow propagation; the second used local peak velocity as the marker. The isovelocity technique followed the flow proximal to the vortex (wavefront) while the peak velocity method followed peak vorticity, and therefore vortex propagation, closely. We conclude that CMM imaging, while limited in measuring absolute velocities, can be utilized to assess inflow vortex ring properties, and thereby provide useful information on diastolic function.     

Effect of exercise on coronary endothelial function in patients with coronary artery disease

BACKGROUND: Studies of the cardioprotective effects of exercise training in patients with coronary artery disease have yielded contradictory results. Exercise training has been associated with improvement in myocardial perfusion even in patients who have progression of coronary atherosclerosis. We therefore conducted a prospective study of the effect of exercise training on endothelial function in patients with coronary artery disease. METHODS: We randomly assigned 19 patients with coronary endothelial dysfunction, indicated by abnormal acetylcholine-induced vasoconstriction, to an exercise-training group (10 patients) or a control group (9 patients). To reduce confounding, patients with coronary risk factors that could be influenced by exercise training (such as diabetes, hypertension, hypercholesterolemia, and smoking) were excluded. In an initial study and after four weeks, the changes in vascular diameter in response to the intracoronary infusion of increasing doses of acetylcholine (0.072, 0.72, and 7.2 microg per minute) were assessed. The mean peak flow velocity was measured by Doppler velocimetry, and the diameter of epicardial coronary vessels was measured by quantitative coronary angiography. RESULTS: In the initial study, the two groups had similar vasoconstrictive responses to acetylcholine. After four weeks of exercise training, coronary-artery constriction in response to acetylcholine at a dose of 7.2 microg per minute was reduced by 54 percent (from a mean [+/-SE] decrease in the luminal diameter of 0.41+/-0.05 mm in the initial study to a decrease of 0.19+/-0.07 mm at four weeks; P<0.05 for the comparison with the change in the control group). In the exercise-training group, the increases in mean peak flow velocity in response to 0.072, 0.72, and 7.2 microg of acetylcholine per minute were 12+/-7, 36+/-11, and 78+/-16 percent, respectively, in the initial study. After four weeks of exercise, the increases in response to acetylcholine were 27+/-7, 73+/-19, and 142+/-28 percent (P<0.01 for the comparison with the control group). Coronary blood-flow reserve (the ratio of the mean peak flow velocity after adenosine infusion to the resting velocity) increased by 29 percent after four weeks of exercise (from 2.8+/-0.2 in the initial study to 3.6+/-0.2 after four weeks; P<0.01 for the comparison with the control group). CONCLUSIONS: Exercise training improves endothelium-dependent vasodilatation both in epicardial coronary vessels and in resistance vessels in patients with coronary artery disease.     

冠脉轻度狭窄患者内皮功能和冠脉血流储备的临床观察

目的:观察冠脉轻度狭窄患者血管内皮功能和冠脉血流储备(CFR)的变化。方法:常规冠脉造影显示冠脉狭窄<50%患者56例,根据冠脉内注射乙酰胆碱(Ach)反应结果分为Ach阳性组与阴性组;运用数字跟踪技术软件测算两组患者CFR,并采血检测超敏C-反应蛋白(hs-CRP)水平。结果:Ach阳性组CFR低于阴性组(P<0.05),hs-CRP高于阴性组(P<0.01)。结论:早期冠心病患者存在内皮功能异常且伴有CFR降低。     

QT interval dispersion changes according to the vessel involved during percutaneous coronary angioplasty

Increased QT dispersion (QTd) is a noninvasive marker of an electrophysiologic abnormality associated with high mortality in coronary artery disease. The purposes of this study were to measure changes in QTd and ST-segment changes immediately before, during and after intracoronary balloon inflation and to determine whether the coronary artery vessel involved and/or the duration of inflation affect(s) QTd. A total of 45 patients (32 men, 13 women, mean age 58 +/- 11 years) who were referred for elective percutaneous transluminal coronary angioplasty were included. The mean QT interval dispersions for all patients before the inflation, during the balloon inflation at 60 sec and after the balloon deflation at 5 min were 68 +/- 13 ms, 82 +/- 16 ms and 71 +/- 13 ms, respectively. There was no significant difference between baseline and 5 min after deflation. The increase in QTd during the balloon inflation was significant (p<0.01). There was no significant QTd change in patients with left circumflex artery (Cx) lesions during inflation and after deflation compared with baseline. The differences were statistically significant only in patients with left anterior descending (LAD) lesions and right coronary artery (RCA) lesions at 60 sec during balloon inflation (p=0.001 vs. p=0.04). Acute reversible myocardial ischemia induced by balloon inflation causes an increase in QTd limited to the LAD and RCA vessels. Therefore, when using QTd as a marker of myocardial repolarization abnormality due to acute reversible ischemia, the involved coronary artery vessel must be taken into account.     

Changes in left ventricular ejection fraction and coronary flow reserve after coronary microembolization

Introduction

Although coronary microembolization (CME) is a frequent phenomenon in patients undergoing percutaneous coronary intervention, few data are available on the changes in left ventricular ejection fraction (LVEF) and coronary flow reserve (CFR) after CME.

Material and methods

In this study, six miniature swine of either sex (body weight 21-25 kg) were used to prepare a CME model. After coronary angiography, 1.2 × 10⁵ microspheres (42 µm) were selectively infused into the left anterior descending artery via an infusion catheter. Left ventricular ejection fraction was evaluated using transthoracic echocardiography; myocardial blood flow was measured using coloured microspheres; and CFR and coronary pressure were measured using Doppler and a pressure wire.

Results

Left ventricular ejection fraction was 0.77 ±0.08 at baseline, 0.69 ±0.08 at 2 h, 0.68 ±0.08 at 6 h, and 0.76 ±0.06 at 1 week (2 h vs. baseline p < 0.05; 6 h vs. baseline p < 0.01). After CME, left ventricular end systolic volume (LVESV) and end diastolic volume (LVEDV) were significant larger 1 week later (p < 0.01 for both), while CFR was significantly reduced at 6 h (1.24 ±0.10 at 6 h vs. 1.77 ±0.30 at baseline, p < 0.01) and myocardial blood flow remained unchanged. Serum ET-1 level was significantly higher only at 6 h after CME (6 h vs. baseline p < 0.05).

Conclusions

Reduction of CFR and LVEF is significant at 6 h after CME and recovers 1 week later with left ventricular dilation.