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.     

Quantification of transmural gradient of blood flow in myocardial ischemia with real-time myocardial contrast echocardiography and dipyridamole stress test

Transmural redistribution of myocardial blood flow (MBF) is the earliest sign of myocardial ischemia. We aimed to evaluate the ability of real-time myocardial contrast echocardiography (MCE) combined with dipyridamole stress to quantify the transmural gradient of MBF during graded coronary stenosis. Real-time MCE was performed in 14 open-chest dogs at seven experimental stages: baseline; hyperemia induced by 6-min infusion of dipyridamole; 50%, 75% and 90% reduction of hyperemic flow after constriction in each stage for 10 min; reperfusion for 10 min; and subtotal occlusion of the left anterior descending coronary artery (LAD) for 90 min. We obtained MCE perfusion parameters from subendocardial (A-endo, beta-endo and A x beta-endo) and subepicardial (A-epi, beta-epi and A x beta-epi) layers of the ventricular septum and calculated their transmural gradients (A-EER, beta-EER and A x beta-EER) and systolic wall thickening (SWT). The sensitivity and specificity of each parameter for predicting 75% reduction of hyperemic flow, which was defined as mild myocardial ischemia, were derived by receiver operating characteristic (ROC) curve analysis. No transmural gradients were found at baseline; during maximal hyperemia and 50% reduction of hyperemic flow. beta-endo, A x beta-endo, beta-EER and A x beta-EER decreased significantly when the hyperemic flow was reduced by 75% or more. In contrast, SWT remained unchanged until the hyperemic flow was reduced by 90%. Among all parameters measured, beta-EER and A x beta-EER had the highest and SWT the lowest sensitivity and specificity in predicting mild myocardial ischemia. In conclusion, real-time MCE combined with dipyridamole stress allows for quantification of the transmural gradient of MBF. beta-EER and A x beta-EER are more sensitive than SWT and other MCE parameters in detecting mild myocardial ischemia.     

经胸多普勒超声无创检测冠心病患者冠状动脉各主要分支血流储备

目的 评价经胸多普勒超声心动图(TTDE)检测冠状动脉各主要分支血流储备的可行性和准确性.方法 临床疑诊冠心病拟行冠状动脉造影的439例患者,在进行冠状动脉造影前1周内进行TTDE检查,检测左前降支(LAD)、左旋支(LCx)和右冠状动脉后降支(PDA)远端的血流储备.在基础状态和持续静脉注射腺苷(140μg·kg-1·min-1)情况下分别测定其血流速度,计算血流储备(CFR)及其诊断冠状动脉狭窄的准确性.结果 439例患者中28支LAD、12支LCx和21支PDA闭塞.LAD的CFR检测成功率为96.8%(395/411),LCx的CFR检测成功率为74.9%(320/427),PDA的CFR检测成功率为83.0%(347/418).以CFR≤2.0和CFR≤1.7分别作为判断冠状动脉狭窄(≥50%)和显著狭窄(≥75%)的标准,诊断LAD、LCx和PDA狭窄的灵敏度和特异度分别为81%和87%,64%和82%,79%和85%,诊断显著狭窄的灵敏度、特异度分别为86%和81%,70%和85%,81%和82%.结论 经胸多普勒超声心动图检测冠状动脉各主要分支血流储备的成功率和判断冠状动脉狭窄的准确性均较高,具有一定临床应用价值.     

静脉弹丸注射氟碳造影剂对冠脉狭窄程度和心肌灌注声学密度定量相关性的研究

目的　探讨静脉弹丸注射氟碳造影剂后心肌显影强度与冠脉狭窄程度的相关性。方法　检测１０条犬冠状动脉左旋支（ＬＣＸ）不同程度狭窄时, 静脉弹丸注射全氟显后左室后壁心肌声学密度。结果　基础状态到ＬＣＸ轻、中、重度狭窄左室后壁心肌声学造影（ＭＣＥ）时间－强度曲线的峰值强度（ＰＩ）和曲线下面积（ＡＵＣ）均逐渐减低, 但相邻两组间差别不显著, ＬＣＸ完全阻断时, ＰＩ、ＡＵＣ均显著减低。结论　ＭＣＥ所测得参数与冠脉狭窄程度呈非线性相关, 但尚不能用于准确区分狭窄程度。     

实时心肌声学造影定量评价不同程度心肌缺血的实验研究

目的：探讨实时心肌声学造影定量诊断不同程度心肌缺血的可行性。方法：12只开胸犬以冠脉缩窄器造成左前降支轻，中，重不同程度狭窄，狭窄前后静滴“全氟显”（速度5ml/min)进行实时心肌声学造影。左室乳头肌中段短轴观察左室前壁心肌显影，室壁厚度和运动，采用动态图像单帧转化法以图像软件分析造影结果。结果：轻度缺血时，心肌显影的视频亮度峰值（VBP）及再灌注速度与狭窄前比较无显著差异，药物负荷状态下差异增大；中，重度缺血时二者明显减低。心肌缺血时，舒张期与收缩期VBP比值正常减低。结论：结合药物负荷，实时心肌声学造影可以定量诊断不同程度心肌缺血。     

双嘧达莫与多巴酚丁胺负荷心肌超声造影探测冠脉狭窄的对比研究

目的对比双嘧达莫和多巴酚丁胺负荷心肌超声造影(MCE)探测静息状态下无心肌血流限制性冠脉狭窄的能力.方法用放置"水膨胀”式缩窄器于冠脉主干近端的方法,建立15只慢性多支冠脉狭窄闭胸犬模型.术后7～10d进行静息、双嘧达莫和多巴酚丁胺的小剂量微泡弹丸式注射法MCE,并同步用放射性标记微球测量心肌血流(MBF).以MBF储备≥3为正常和＜3为异常供血区.结果两种药物引起MBF增加,在正常和异常供血区均相近.两种药物负荷时,MCE示异常供血区灌注缺损的范围和程度相同.两种药物作用下异常供血区的峰值声强度(VI)均较正常供血区低(P＜0.05),异常和正常供血区峰值VI比值非常接近;且双嘧达莫和多巴酚丁胺的峰值VI比值均与相应的MBF比值呈良好的线性正相关(r=0.90和0.87,P＜0.0001).结论双嘧达莫和多巴酚丁胺负荷MCE探测冠脉狭窄的能力相近.因此,两者均可用于慢性冠脉狭窄的诊断.     

Quantification of myocardial perfusion and determination of coronary stenosis severity during hyperemia using real-time myocardial contrast echocardiography

Although regional myocardial perfusion can be currently quantified with myocardial contrast echocardiography (MCE) by using intermittent harmonic imaging (IHI), the method is tedious and time-consuming in the clinical setting. We hypothesized that regional myocardial perfusion can be quantified and the severity of coronary stenosis determined during hyperemia with MCE using real-time imaging (RTI) where microbubbles are not destroyed. Six open-chest dogs were studied during maximal hyperemia induced by adenosine in the absence or presence of coronary stenoses varying from mild to severe. Myocardial blood flow (MBF) was measured at each stage by using radiolabeled microspheres. MCE was performed using both IHI and RTI. Data for the latter were acquired in both end-systole and end-diastole. No differences were found between myocardial flow velocity (MFV) derived from IHI and RTI when end-systolic frames were used for the latter. MFV was consistently higher for RTI (P <.01) when end-diastolic frames were used. A linear relation was noted between MFV and radiolabeled microsphere-derived MBF ratios from the stenosed and the normal beds when end-systolic frames were used for RTI (r = 0.78, P <.001), whereas no relation was found when end-diastolic frames were used (r = 0.08, P =.78). The scatter for assessing MBF (A.beta) was minimal for IHI and RTI (9%-10%) with end-systolic frames, whereas that for RTI with end-diastolic frames was large (30%). Furthermore the correlation with radiolabeled microsphere-derived MBF was significantly (P <.01) weaker with RTI when end-diastolic frames were used (r = 0.53) than when end-systolic frames (r = 0.94) or IHI was used (r = 0.99). Data acquisition for IHI was 10 minutes, whereas it was 8 seconds for RTI. Thus, RTI can be used to quantify regional myocardial perfusion and stenosis severity during MCE. Only end-systolic frames, however, provide accurate data. RTI offers a rapid and easy means of assessing regional myocardial perfusion with MCE.     

A comparison of video and digital data in the assessment of myocardial perfusion abnormalities by myocardial contrast echocardiography

Objective: The objective of the present study was to compare the digital and video data of myocardial contrast echocardiography (MCE) to assess altered myocardial blood flow produced by graded coronary stenoses. Methods: Three grades of left anterior descending (LAD) coronary artery stenosis and occlusion were created in eight open-chest canine models. MCE was performed with BR1 infusion by harmonic power Doppler with ECG gated intermittent triggered imaging at pulsing intervals ranging from 1:1 to 1:10. For images that were recorded simultaneously on both a videotape (video data) and an optical disk (digital data), myocardial signal intensity in the LAD region was plotted vs. pulsing intervals and was fitted to an exponential function:y=A(1 − e^−bt ), where A is the peak plateau signal intensity, and b is the rate of signal intensity rise for quantification of myocardial blood flow. Results: Both values for A and b progressively decreased with a greater level of stenosis. The correlation of A with myocardial blood flow (determined by use of fluorescent microspheres) was weak with digital data (r= 0.38, p= 0.037), and was insignificant with video data (r= 0.16, p= 0.38). The correlation of b with microsphere-derived myocardial blood flow was better than that of A with both video and digital data, and was similar between the two kinds of data (video:r= 0.69, p < 0.0001; digital:r= 0.68, p < 0.0001). Conclusions: Video and digital MCE data are equivalent in their ability to quantify altered myocardial blood flow produced by graded coronary stenoses.     

Thrombosis in one coronary artery causes generalized coronary vasoconstriction in a dog model of unstable angina

We investigated the effect of thrombosis in one coronary artery upon the vascular resistance of another coronary artery. In previous investigations, using an animal model of unstable angina, we have observed increased resistance downstream from thrombus within a left circumflex coronary artery (LCx) stenosis and vasoconstriction of collateral vessels from the left anterior descending artery (LAD) supplying the distal LCx vascular bed. In the present paper, we induced thrombosis within a stenosis of the LCx of 16 beagle dogs, and observed the changes in blood flow to the myocardium supplied by the LAD using the radioactive microsphere technique. This blood flow decreased with thrombosis (P = 0.005) in these animals, whereas it did not do so in three time-control experiments. The pressures across the coronary vascular bed, i.e. arterial pressure to coronary venous pressure (coronary sinus catheter), did not change. Thus the vascular resistance of the LAD bed increased significantly from 147 +/- ll.5 mmHg/ml/sec/g of tissue to 172 +/- 13.4 mmHg/ml/sec/g of tissue (P = 0.02). As the LAD territory is not perfused with blood from the artery containing thrombus, we conclude that the effect observed is caused either by release of vasoconstrictors from the thrombus into the general circulation, or by activation of a neural reflex vasoconstriction. The study suggests that unstable angina involving thrombosis in one coronary artery is a global coronary vascular disease.     

Measurement of coronary flow velocity reserve in the posterior descending coronary artery by contrast-enhanced transthoracic Doppler echocardiography.

BACKGROUND: Although the measurement of coronary flow velocity (CFV) reserve (CFVR) in the left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography has been established, its success rate in the posterior descending coronary artery (PD) is still limited. OBJECTIVE: This study reports the feasibility and diagnostic accuracy of measuring CFVR in the PD by transthoracic Doppler echocardiography. METHODS: CFVR in both the distal LAD and the PD was measured in 151 consecutive patients before coronary angiography. PD flow was investigated under the guidance of a nondirectional Doppler color flow map with harmonic imaging in the modified apical 2-chamber view. Intravenous contrast agent, Levovist, was injected to enhance the CFV envelope at baseline and during hyperemia. RESULTS: CFVR was obtained in 145 patients in the LAD and 126 patients in the PD (P <.001). The success rate of CFVR measurement in the PD was significantly higher in the last 50 patients (88%) than it was in the first 50 patients (72%) (P <.05). CFVR in the PD was significantly lower for patients with significant stenosis of the artery supplying the PD than it was in those without stenosis (1.58 +/- 0.59 vs 2.45 +/- 0.72, P <.001). CFVR in the distal LAD was 1.40 +/- 0.62 in patients with significant LAD stenosis and 2.45 +/- 0.80 in those without stenosis (P <.001). If a cut-off value of CFVR < 2 was used, sensitivity, specificity, and accuracy for the diagnosis of significant (>50%) stenosis of the artery supplying the PD were 84%, 83%, and 83%, respectively, whereas for the LAD they were 91%, 75%, and 80%, respectively. CONCLUSIONS: Noninvasive measurement of CFVR in the PD could be obtained in the majority of unselected patients using a nondirectional Doppler color flow map and contrast-enhanced harmonic imaging. The diagnostic accuracy of CFVR in the PD is similar to that of the LAD and, hence, has a potential clinical use.     

二次谐波显像评价冠脉血流储备和狭窄程度的实验研究

目的：探讨二次谐波显像在定量评价冠脉血流储备和冠脉狭窄程度的价值。方法：采用二次谐波显像技术对１１条冠脉不同狭窄程度的动物模型进行心肌声学造影。结果：正常或狭窄冠脉灌注区心肌的造影时间－强度曲线的曲线下面积（ＡＵＣ）在罂粟碱介入前后的相对变化率与用电磁流量计测定的冠脉血流量的相对变化率即冠脉血流储备的相关性良好（ｒ＝０．７７,Ｐ＝０．０００２）;而且狭窄冠脉支配的心肌缺血区在罂粟碱介入前后ＡＵＣ的相对变化率与冠脉狭窄程度也有一定的相关性（ｒ＝０．７２,Ｐ＝０．０２。结论：二次谐波显像技术可以定量评价冠脉狭窄后冠脉血流储备的变化,并且在一定范围内定量反映冠脉狭窄程度     

Assessment of flow mismatch with pharmacologic stress test on myocardial contrast echocardiography in a model of critical stenosis: adenosine triphosphate and dipyridamole.

Although adenosine triphosphate (ATP) is a favorable vasodilator because of its short-acting duration, the agent's effectiveness in facilitating the diagnosis of myocardial ischemia with myocardial contrast echocardiography (MCE) is not fully understood. The goal of this study was to examine the efficacy of intravenous ATP administration (0.15 to 0.30 mg/kg/min for 5 minutes) in diagnosing the flow mismatch with MCE. To achieve this, a critical stenosis was produced in the left circumflex artery in 10 anesthetized dogs. The peak intensity ratio of risk area to control area was reduced by ATP from 0.51 +/- 0.19 to 0.31 +/- 0.12 (P <.05). Systolic wall thickening of the risk area did not change significantly (32.8% +/- 9.8% to 27.5% +/- 12.8%). These changes did not differ from those obtained after dipyridamole. We conclude that MCE with intravenous ATP administration is as useful as the dipyridamole method for diagnosing critical coronary stenosis.     

Noninvasive assessment of coronary flow reserve with transthoracic signal-enhanced Doppler echocardiography.

OBJECTIVES: The feasibility of noninvasive assessment of coronary flow reserve (CFR) in the distal left anterior descending artery (LAD) with echocardiography-enhanced transthoracic pulsed wave Doppler guided by high-resolution transthoracic color Doppler (TTCD) was investigated. The results were compared with the degree of coronary diameter stenosis obtained during cardiac catheterization. BACKGROUND: Assessment of CFR has proven to be useful in the selection of patients undergoing invasive treatment of coronary artery disease and in estimating their prognosis. However, CFR could only be determined invasively in everyday practice during catheterization procedures. Recent development of high-resolution TTCD allows transthoracic visualization of distal LAD and supra-apical intramyocardial perforator branches and noninvasive measurement of CFR with pulsed wave Doppler technique. METHODS: CFR was determined by measuring the ratio of pulsed wave Doppler time velocity integral during adenosine-induced hyperemia (140 microgram/kg/min intravenously) to baseline value. If the baseline Doppler signal of LAD flow was insufficient, an echocardiography (echo) enhancer (Levovist) was used. Forty-five patients were examined by TTCD (7-MHz B-mode, 5-MHz color Doppler, and 3.5-MHz pulsed wave Doppler) after coronary angiography had been performed. Group 1 consisted of 15 patients without heart disease, group 2 of 15 patients with 50% to 85% isolated LAD diameter stenosis, and group 3 of 15 patients with >85% LAD diameter stenosis. RESULTS: Peripheral LAD coronary flow at baseline condition was assessed in 40 (88%) patients with TTCD. CFR could be quantified in 36 (80%) of the 45 patients: in 18 patients without echo enhancer, and in 18 patients with echo-enhancing agent. CFR could not be assessed in 9 (20%) patients. CFR in the various groups was as follows: group 1, 3. 13 +/- 0.57; group 2, 2.23 +/- 0.20 (vs group 1: P <.01); and group 3, 1.64 +/- 0.30 (vs group 2: P <.02). CONCLUSION: CFR in the LAD can be determined in 80% of patients with pulsed wave Doppler guided by high-resolution TTCD combined with intravenously administered echo-enhancing agent.     

Noninvasive vessel-selective perfusion imaging with intravenous myocardial contrast echocardiography.

BACKGROUND: Intravenous myocardial contrast echocardiography (MCE) cannot identify each perfusion area of coronary vessels separately. However, by destroying microbubbles passing through a specific vessel using high-power ultrasound during intravenous MCE, vessel-selective perfusion imaging (VSPI) may be feasible. METHODS: In 10 open-chest dogs, intermittent short-axis images were obtained during contrast agent infusion using an ultrasound system. For VSPI, a probe coupled to another ultrasound machine was placed on the proximal left circumflex coronary artery (LCx). High-power ultrasound pulses were transmitted to destroy bubbles passing through the LCx. A negative contrast area on VSPI was considered to represent the perfusion area of the LCx (LCx-VSPI). A negative contrast area on conventional MCE during LCx occlusion and a region without staining by Evans blue dye were used as gold standards for defining the LCx perfusion area. LCx-VSPI was compared with a negative contrast area on conventional MCE during LCx occlusion and a region without staining by Evans blue dye. RESULTS: Despite lack of LCx occlusion, high-power destructive pulses produced a definite area of negative contrast on the LCx region. Decreased power of ultrasound pulses resulted in disappearance of the negative contrast area. An excellent relationship was demonstrated between both LCx-VSPI and a negative contrast area on conventional MCE during LCx occlusion (r = 0.93, P <.0001), and LCx-VSPI and a region without staining by Evans blue dye (r = 0.92, P =.0002). CONCLUSION: VSPI during intravenous MCE may be feasible for noninvasive assessment of perfusion areas associated with specific vessels.     

声学造影诊断无血流限制性冠脉狭窄的新方法

目的探讨应用声学造影(MCE)在非负荷状态下诊断无血流限制性冠脉狭窄(NFLS)的可行性.方法分别在犬的前降支(LAD)无狭窄及两种不同程度的NFLS状态,MCE 采用高机械指数连续脉冲成像方法;比较不同状态下心脏收缩末声学造影强度(VIS)与舒张末造影强度(VID)的比值,探讨应用MCE在非负荷状态下诊断NFLS的可行性.结果随着冠脉狭窄程度的加重,VIS与VID比值进行性增大(P＜0 .05) .结论测量心脏收缩期与舒张期声学造影强度比值可用于非负荷状态下诊断无血流限制性的冠脉狭窄.     

静脉心肌声学造影定量评价冠脉微循环血流灌注

目的　评价静脉心肌声学造影定量评估冠脉微循环血流灌注的可行性。方法　对 12条犬于左前降支 (LAD)狭窄前后行静脉心肌声学造影。结果　时间 强度曲线参数中峰强度和曲线面积较基础状态明显降低 (P <0 .0 1) ,两种状态下以峰强度和曲线下面积 (AUC)与冠脉微循环血流 (CBF)有显著的相关性 (峰强度 :r =0 .940 5～ 0 .9666,P =0 .0 0 0 5～ 0 .0 0 0 1;AUC :r =0 .82 3 9～ 0 .9761,P =0 .0 10 3～0 .0 0 5 6)。)结论　静脉心肌声学造影可定量评价冠脉微循环血流灌注     

Real-Time Myocardial Contrast Echocardiography in Rat: Infusion Versus Bolus Administration

To compare the feasibility of real-time myocardial contrast echocardiography (MCE) in rats with infusion and bolus administration of a second-generation ultrasound contrast agent BR1. B-mode real-time MCE was performed in 12 Sprague Dawley rats following the BR1 infusion or bolus injection. The myocardium signal intensity (SI) was plotted against time and was fitted to exponential functions. The plateau SI (A) and rate of SI increase (β) for the infusion study and peak signal intensity (PSI) for the bolus study were obtained. ^99mTc-Sestamibi and Evans blue were used to assess myocardial blood perfusion and to calculate the myocardium perfusion defect area ex vivo. High-quality real-time MCE images were successfully obtained using each method. At baseline, all LV segments showed even contrast distribution. Following left anterior descending coronary artery (LAD) ligation, significant perfusion defect was observed in LAD beds with a significantly decreased A* β and PSI values compared with LCx beds (Infusion: A*β _LAD: 5.42 ± 1.57dB, A*β _LCx: 46.52 ± 5.32dB, p < 0.05; Bolus: PSI _LAD: 2.11 ± 0.67dB, PSI _LCx: 20.68 ± 0.72 dB, p < 0.05), which was consistent with ^99mTc-Sestamibi distribution findings. Myocardial perfusion defect areas, assessed by both methods, showed no differences and showed good correlation with Evans blue staining. ED frames were more favorable for imaging analysis. Both infusion and bolus administration of the contrast agent combined with real-time MCE technique can provide a reliable and noninvasive approach for myocardial perfusion assessment in rats and the infusion method was more suitable for quantitative analysis of myocardial blood flow. (E-mail: suhaili@fmmu.edu.cn)     

Assessment of Left Atrial Work During Acute Coronary Occlusion

Left atrial (LA) work can be measured through speckle tracking echocardiography by calculating LA pressure–strain loop area, which includes two distinct phases of active contraction/relaxation (A-work) and passive dilation/emptying (V-work). Echocardiographic and hemodynamic data were acquired at baseline and during occlusions of left anterior descending (LAD: n?=?7) and left circumflex (LCx: n?=?9) coronary arteries in dogs. Left ventricular (LV) circumferential strain was decreased and mean LA pressure was increased in both occlusions. Doppler-derived stroke volume was maintained during LAD occlusion, but it decreased during LCx occlusion. A-work increased during LAD occlusion, but it did not change during LCx occlusion. V-work decreased during LCx occlusion more than during LAD occlusion. The compensatory mechanism of LA function was limited during LCx occlusion, but this occurred during LAD occlusion. This study provided insight into a role of LA function in variable hemodynamic consequences in acute myocardial infarction.     

Incidental renal artery stenosis among a prospective cohort of hypertensive patients undergoing coronary angiography

OBJECTIVE: To determine the feasibility, safety, and clinical yield of angiographic screening among hypertensive patients undergoing coronary angiography. PATIENTS AND METHODS: This study was a prospective cohort analysis of hypertensive patients who underwent cardiac catheterization at a tertiary care referral center from July 1998 to March 1999. Abdominal aortography was performed to screen for renal artery stenosis, the percentage of which was measured. RESULTS: The mean +/- SD age of the 297 study patients was 64.9+/-10.2 years; 58.6% were male, and 98.0% were white. Mean +/- SD systolic/diastolic blood pressure was 142.8+/-22.5/79.6+/-11.4 mm Hg. Aortography required a mean incremental dose of 62+/-9 mL of nonionic contrast agent. No complications were attributable to aortography. Of 680 renal arteries, 611 (90%) were visualized adequately. Also, 53% of patients had normal renal arteries, 28% had stenoses less than 50%, and 19.2% had stenoses of 50% or more. Renal artery stenosis was bilateral in 3.7% of patients and high grade (>70% stenosis) in 7%. Patients with renal artery stenosis were more likely to have had a previous coronary intervention. In multivariate analysis, systolic blood pressure (odds ratio [OR], 1.2; 95% confidence interval [CI], 1.03-138; P=.02), history of stroke or transient ischemic attack (OR, 2.7; 95% CI, 1.27-5.78; P=.01), and cancer (OR, 2.0; 95% CI, 1.02-3.82; P=.04) independently correlated with renal artery stenosis of 50% or more. CONCLUSION: The prevalence of incidental renal artery stenosis among hypertensive patients undergoing coronary catheterization is significant. Therefore, screening abdominal aortography should be considered in these patients to better define their risk of cardiovascular complications.     

Quantification of myocardial blood flow and assessment of its transmural distribution with real-time power modulation myocardial contrast echocardiography.

BACKGROUND: The purpose of this study was to examine the ability of real-time myocardial contrast echocardiography (MCE) with power modulation to quantitate myocardial blood flow (MBF) and to assess its transmural distribution in open-chest dogs undergoing partial or total coronary stenoses. METHODS AND RESULTS: MBF was measured in 12 dogs instrumented with a cuff occluder around the left anterior descending coronary artery at rest, during partial coronary stenosis (during infusion of adenosine), and during coronary occlusion. The MCE-derived rate of microbubble velocity, beta, and myocardial blood volume, A, were obtained by curve fitting of videointensity versus time plots, after the transient destruction of microbubbles by high-energy ultrasound. The data were compared with MBF measured with radiolabeled microspheres. Significant correlations were found between radiolabeled microsphere-derived MBF and both beta (r = 0.93) and the product of A x beta (r = 0.91). MCE beta reserve also correlated well with microsphere-derived flow reserve. Comparing endocardial/epicardial MCE ratios and microsphere-derived MBF ratios, significant correlation was also found between endomicropsheres/epimicrospheres MBF ratio and both endo/epi beta (r = 0.90) and endo/epi A x beta (r = 0.88). CONCLUSIONS: Real-time power modulation MCE allows for an accurate quantification of MBF and of its transmural distribution in open-chest dogs undergoing partial or total coronary stenoses.