Transthoracic Doppler assessment of coronary flow velocity reserve in children with Kawasaki disease: comparison with coronary angiography and thallium-201 imaging

OBJECTIVES: The purpose of this study was to determine the feasibility of coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) in children with Kawasaki disease (KD). BACKGROUND: Doppler-derived CFVR is a reliable marker predicting the presence of myocardial ischemia. METHODS: We studied 49 patients (median age 11 years) with KD. The CFVR was calculated as the ratio of hyperemic to basal peak (peak CFVR) and mean (mean CFVR) diastolic flow velocities in the posterior descending coronary artery (PD) and left anterior descending coronary artery (LAD). The CFVR measurements by TTDE were compared with the results of coronary angiography, thallium-201 (Tl-201) single-photon emission computed tomography (SPECT), and intracoronary Doppler study. RESULTS: The CFVR measurements by TTDE were obtained in 92 (94%) of 98 vessels of the PD and LAD in 49 study patients. Both peak and mean CFVRs for 21 stenotic vessels were significantly smaller than those for 35 normal vessels and for 20 vessels with aneurysmal lesions (p < 0.0001). Peak and mean CFVR <2.0 predicted significant coronary stenosis, as determined by coronary angiography, with sensitivities and specificities of 89% and 96% and 89% and 97%, respectively. Also, both peak and mean CFVRs were correlated with reversible perfusion defects on Tl-201 SPECT (agreement 80%; kappa 0.4). The correlation between peak and mean CFVRs determined by the TTDE and intracoronary Doppler studies in 36 vessels of 23 patients were 0.76 and 0.80, respectively. CONCLUSIONS: The CFVR measured by TTDE predicts the presence of significant coronary stenosis of either the right coronary artery or LAD, as well as myocardial ischemia of these territories in children with KD.     

Using transthoracic Doppler echocardiography to diagnose reduced coronary flow velocity reserve in the posterior descending coronary artery in children with elevated right ventricular pressure.

BACKGROUND: Advances in transthoracic Doppler echocardiography enable noninvasive measurements of coronary flow velocity and coronary flow velocity reserve (CFVR) in the posterior descending coronary artery (PD). METHODS AND RESULTS: To evaluate CFVR in the PD of children with elevated right ventricular (RV) pressure, 19 children with RV pressure overload and 13 age-matched controls with normal RV pressure were studied using transthoracic Doppler echocardiography. Average peak flow velocity (APV) was measured at rest and in hyperemic conditions (intravenous administration of adenosine of 0.16 mg.kg(-1).min(-1)). Compared with controls, the PD CFVR was significantly reduced in the patients with elevated RV pressure (1.87+/-0.42 vs 2.49+/-0.55, p<0.01) because their mean baseline APV was significantly greater (27+/-6 vs 19+/-4 cm/s, p<0.01), although hyperemic APV was not significantly different (49+/-10 vs 48+/-14 cm/s, p=NS). CONCLUSIONS: PD CFVR is limited in patients with elevated RV pressure because of elevation of the baseline resting flow velocity.     

Cut-off value of coronary flow velocity reserve by transthoracic Doppler echocardiography for diagnosis of significant left anterior descending artery stenosis in patients with coronary risk factors

The purpose of this study was to evaluate the adequate cut-off value of coronary flow velocity reserve (CFVR) with transthoracic Doppler echocardiography for diagnoses of significant left anterior descending (LAD) artery stenosis in a large study population with various coronary risk factors. CFVR, which has been used for evaluation of significant coronary artery stenosis, can be reduced despite angiographically normal coronary arteries in patients with various coronary risk factors. However, the adequate cut-off value of CFVR for diagnosing significant LAD stenosis has not been fully established in patients with coronary risk factors. We examined 138 consecutive patients who underwent coronary angiography. Clinical histories of coronary risk factors were determined from interviews or medical records. CFVR assessment in the LAD artery by transthoracic Doppler echocardiography was performed in all patients. Of the 138 patients, 30 had significant stenosis, and the remainder had no stenotic lesions in the LAD artery. Receiver-operating characteristic curves for detection of significant LAD stenosis showed that a cut-off value of <2.0 was extremely precise. A cut-off value <2.0 of CFVR had a sensitivity of 90%, a specificity of 93%, a positive predictive value of 77%, and a negative predictive value of 97% for the presence of significant LAD stenosis. A cut-off value <2.0 of CFVR by transthoracic Doppler echocardiography was adequate for the diagnosis of significant LAD stenosis in a population that included patients with coronary risk factors.     

Noninvasive assessment of coronary flow velocity and coronary flow velocity reserve in the left anterior descending coronary artery by Doppler echocardiography: Comparison with invasive technique

Objectives. The purpose of this study was to evaluate whether transthoracic Doppler echocardiography (TTDE) can reliably measure coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) in the left anterior descending coronary artery (LAD) in the clinical setting.Background. Coronary flow velocity measurement has provided useful clinical and physiologic information. Advancement in TTDE provides noninvasive measurement of CFV and CFVR in the distal LAD.Methods. In 23 patients, CFV in the distal LAD was measured by TTDE (5 or 3.5 MHz) under the guidance of color Doppler flow mapping at the time of Doppler guide wire (DGW) examination. Coronary flow velocity in the distal LAD were measured at baseline and hyperemic conditions (intravenous administration of adenosine 0.14 mg/kg/min) by both TTDE and DGW techniques. Coronary flow velocity reserve was defined as the ratio of peak hyperemic to basal averaged peak velocity in the distal LAD.Results. Clear envelopes of basal and hyperemic CFV in the distal LAD were obtained in 18 (78%) of 23 study patients by TTDE. There were excellent correlations between TTDE and DGW methods for the measurements of CFV (averaged peak velocity: r = 0.97, y = 0.94x + 0.40; averaged diastolic peak velocity: r = 0.97, y = 0.94x + 0.69; systolic peak velocities: r = 0.97, y = 0.91x + 0.87; diastolic peak velocity: r = 0.98, y = 0.95x + 1.10). Coronary flow velocity reserve from TTDE correlated highly with those from DGW examinations (r = 0.94, y = 0.95x + 0.21).Conclusions. Noninvasive measurement of CFV and CFVR in the distal LAD using TTDE accurately reflects invasive measurement of CFV and CFVR by DGW method.     

Noninvasive coronary flow velocity reserve measurement in the posterior descending coronary artery for detecting coronary stenosis in the right coronary artery using contrast-enhanced transthoracic Doppler echocardiography

BACKGROUND: Coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) has been found to be useful for assessing left anterior descending coronary artery (LAD) stenosis. However, this method has been restricted only for the LAD. The purpose of this study was to detect severe right coronary artery (RCA) stenosis by CFVR measurement using contrast-enhanced TTDE. METHODS: In 60 consecutive patients with angina pectoris (mean (SD) age: 60 (11), 18 women), coronary flow velocities in the RCA were recorded in the postero-descending coronary artery by contrast-enhanced TTDE at rest and during hyperemia induced by intravenous infusion of adenosine triphosphate (140 mcg/ml/kg). CFVR was calculated as the ratio of hyperemic to basal peak and mean diastolic flow velocity. CFVR measurements by TTDE were compared with the results of coronary angiography performed within 1 week. RESULTS: Coronary flow velocity was successfully recorded in 49 (82%) of the 60 patients with contrast agent. CFVR (mean (SD)) was 1.4 (0.4) in patients with, and 2.6 (0.6) in patients without significant stenosis in the RCA (%diameter stenosis > 75%, P < 0.001). Using the cutoff value 2.0 for CFVR in the RCA, its sensitivity and specificity in detecting significant stenosis in the RCA were 88% and 91%, respectively. CONCLUSION: CFVR measurement in the postero-descending coronary artery by contrast enhanced TTDE is a new, noninvasive method to detect significant stenosis in the RCA.     

Effect of azithromycin therapy on coronary circulation in patients with coronary artery disease

This study examined the effect of azithromycin therapy on the coronary microcirculation using measurement of coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography in 35 patients with coronary artery disease. CFVR increased significantly after azithromycin therapy (3.0 +/- 0.7 vs 3.5 +/- 0.7, p <0.001). The changes in CFVR were negatively correlated with changes in high-sensitivity C-reactive protein levels in patients receiving azithromycin.     

Evaluation of improved coronary flow velocity reserve using transthoracic Doppler echocardiography after single LDL apheresis

The purpose of this study was to clarify whether coronary flow velocity reserve (CFVR), evaluated by adenosine 5'-triphosphate-induced hyperemia, is improved by single low-density lipoprotein (LDL) apheresis. Lipid lowering therapy is known to improve endothelium-dependent vasodilatation in forearm or coronary resistant vessels. However, few reports have studied the effect of acute LDL reduction on CFVR. Methods: Seven patients with familial hypercholesterolemia and significant coronary stenosis except in the left anterior descending artery (LAD) were enrolled in this study. Coronary flow velocity reserve was estimated before and after LDL apheresis using transthoracic Doppler echocardiography (TTDE), which detects the flow velocity at the distal site of the LAD. Although the averaged diastolic peak velocity (ADPV) during ATP-induced hyperemia was similar before and after LDL apheresis, the ADPV at baseline decreased from 30.69 to 25.56 cm/s, resulting in an increased CFVR from 1.78 to 2.10 (P < 0.001). Plasma bradykinin and 6 keto PGF1alpha increased while fibrinogen and plasma viscosity decreased after apheresis. Single LDL apheresis improves CFVR according to TTDE analysis because of the decreasing ADPV at baseline, which is thought to be induced by epicardial coronary artery dilatation and improved microvessel function. This is the result of various factors, such as changes in plasma LDL cholesterol, bradykinin and PGI2 levels with LDL apheresis.     

Evaluation of coronary flow velocity and coronary flow reserve before and after coronary angioplasty using transthoracic Doppler echocardiography and Doppler guide wire

Evaluation of left anterior descending coronary (LAD) blood flow before and after coronary angioplasty was carried out non-invasively by ultrasonic Doppler echocardiography with a newly developed digital, high-frequency, high-resolution transthoracic ultrasonic Doppler flowmeter and a 7.5 MHz probe. The results were compared with those obtained using an intracoronary Doppler guide wire. Sixteen patients, 12 males and 4 females (mean age 57 +/- 14 years) with old myocardial infarction (8 patients) and angina pectoris (8 patients) were studied. Coronary flow reserve was compared following intravenous administration of adenosine triphosphate in 12 patients. The LAD blood flow was detected in 15 of 16 patients. There was a significant increase in the diastolic peak velocity from 22.2 +/- 10.6 to 29.4 +/- 14.6 cm/sec (mean +/- SD) and the coronary flow reserve from 1.8 +/- 0.3 to 2.8 +/- 0.6 (mean +/- SD). There was a good correlation between the data obtained using transthoracic flow measurement and intracoronary flow measurement (r = 0.61, p < 0.05). LAD blood flow can be easily detected parasternally using a digital, high frequency, high-resolution ultrasonic Doppler flowmeter. This method may be applicable for judging the efficacy of coronary angioplasty by measuring coronary flow reserve and for observing the clinical course of the patient non-invasively.     

Value of preoperative echocardiography in the prediction of postoperative atrial fibrillation following isolated coronary artery bypass grafting

The value of echocardiography, especially tissue Doppler imaging (TDI), in the assessment of risk of postoperative atrial fibrillation (AF) after coronary artery bypass grafting (CABG) is not clear. One hundred two consecutive patients (80 men; mean age 61 +/- 10 years) who underwent elective isolated CABG were included in the study. All patients underwent conventional transthoracic echocardiography and TDI of the left and right heart before surgery. Also, 24-hour Holter recordings were obtained for all patients. The study end point was the development of postoperative AF. The surgical mortality rate was 2%. Postoperative AF occurred in 18 patients (18%). Patients with postoperative AF have been significantly older than patients without postoperative AF (73 +/- 7 vs 58 +/- 9 years, respectively; p <0.001). Compared with patients without postoperative AF, a significantly higher proportion of patients with postoperative AF experienced paroxysmal AF before surgery (6% vs 33%, respectively; p = 0.001). Patients with postoperative AF had a significantly larger mean left atrial diameter compared with patients without postoperative AF (37 +/- 3 vs 35 +/- 3 mm, respectively; p = 0.012). Multivariate logistic regression analysis identified age as the most significant predictor of postoperative AF (odds ratio 1.254, 95% confidence interval 1.127 to 1.396; p <0.001). Of the echocardiographic variables, only left atrial diameter was identified as a significant predictor of postoperative AF (odds ratio 1.250, 95% confidence interval 1.055 to 1.562; p = 0.047). In conclusion, in the prediction of postoperative AF after isolated CABG, preoperative transthoracic echocardiography, including both conventional echocardiography and TDI, is of little value.     

Assessment of flow velocity reserve by transthoracic Doppler echocardiography and venous adenosine infusion before and after left anterior descending coronary artery stenting.

OBJECTIVES: We sought to evaluate whether coronary flow velocity reserve (CFR) (the ratio between hyperemic and baseline peak flow velocity), as measured by transthoracic Doppler echocardiography during adenosine infusion, allows detection of flow changes in the left anterior descending coronary artery (LAD) before and after stenting. BACKGROUND: The immediate post-stenting evaluation of CFR by intracoronary Doppler has shown mixed results, due to reactive hyperemia and microvascular stunning. Noninvasive coronary Doppler echocardiography may be a more reliable measure than intracoronary Doppler. METHODS: Transthoracic Doppler echocardiography during 90-s venous adenosine infusion (140 microg/kg body weight per min) was used to measure CFR of the LAD in 45 patients before and 3.7 +/- 2 days after successful stenting, as well as in 25 subjects with an angiographically normal LAD (control group). RESULTS: Adequate Doppler spectra were obtained in 96% of the patients. Pre-stent CFR was significantly lower in patients than in control subjects (diastolic CFR: 1.45 +/- 0.5 vs. 2.72 +/- 0.71, p < 0.01; systolic CFR: 1.61 +/- 1.02 vs. 2.41 +/- 0.68, p < 0.01) and increased toward the normal range after stenting (diastolic CFR: 2.58 +/- 0.7 vs. 2.72 +/- 0.75, p = NS; systolic CFR: 2.43 +/- 1.01 vs. 2.41 +/- 0.52, p = NS). Diastolic CFR was often damped, suggesting coronary steal in patients with > or =90% versus <90% LAD stenosis (0.86 +/- 0.23 vs. 1.69 +/- 0.43, p < 0.01). Coronary stenting normalized diastolic CFR in these two groups (2.45 +/- 0.77 and 2.64 +/- 0.69, respectively, p = NS), even though impaired diastolic CFR persisted in three of four patients with > or =90% stenosis. Stenosis of the LAD was better discriminated by diastolic (F = 49.30) than systolic (F = 12.20) CFR (both p < 0.01). CONCLUSIONS: Coronary flow reserve, as measured by transthoracic Doppler echocardiography, is impaired in LAD disease; it may identify patients with > or =90% stenosis; and it normalizes early after stenting, even in patients with > or =90% stenosis.     

应用经胸冠状动脉血流显像技术评价支架术前后冠脉血流储备

目的采用经胸多普勒超声心动图冠状动脉血流显像技术观察支架术前后冠状动脉血流速度的变化,评价其对冠状动脉血流储备（CFR）的影响。方法22例冠心病患者(男18例,女4例),平均年龄（53.2±6.7）岁。对狭窄的冠状动脉行经皮冠状动脉腔内成形术（PTCA）后各置入一枚支架。分别于木前、术后72h内采用经胸多普勒冠状动脉血流显像技术记录狭窄远端静息舒张期血流峰速(r-Vd)、注射潘生丁及等长握力实验时最大舒张期血流峰速(d-Vd)及CFR。结果22例患者行支架术均获成功,狭窄率由术前(83.5±8.9)%,降至术后(5.2±9)%(P<0.05)。20支冠脉获得理想多普勒频谱（检出率90.9％）;支架术后r-Vd较术前r-Vd有增加趋势,但无统计学意义;术后静脉注射潘生丁后最大d-Vd及CFR均较术前明显增加［（0.92±0.22)m/svs(0.52±0.18)m/s,2.94±1.16vs1.88±0.40,P均<0.01］。30％患者术后CFR仍<2.0,此组与CFR≥2.0患者组比较,支架术后r-Vd明显增高［(0.45±0.19)m/svs(0.27±0.12)m/s,P<0.05］。少数患者(约18%,4／22)术前出现心绞痛,头昏等不适,静注氨茶碱或(和)含化硝酸甘油可迅速缓解。结论支架术能明显增加冠状动脉血流储备。采用经胸多普勒冠脉血流显像技术结合潘生丁、握力试验是一可行的无创性评价冠心病患者冠脉血流储备及介入治疗疗效的新方法。     

Transthoracic Doppler echocardiographic coronary flow imaging in identification of left anterior descending coronary artery stenosis in patients with left bundle branch block

Background: Conventional noninvasive methods have well‐known limitations for the detection of coronary artery disease (CAD) in patients with left bundle branch block (LBBB). However, advancements in Doppler echocardiography permit transthoracic imaging of coronary flow velocities (CFV) and measurement of coronary flow reserve (CFR). Our aim was to evaluate the diagnostic value of transthoracic CFR measurements for detection of significant left anterior descending (LAD) stenosis in patients with LBBB and compare it to that of myocardial perfusion scintigraphy (MPS). Methods: Simultaneous transthoracic CFR measurements and MPS were analyzed in 44 consecutive patients with suspected CAD and permanent LBBB. Typical diastolic predominant phasic CFV Doppler spectra of distal LAD were obtained at rest and during a two‐step (0.56–0.84 mg/kg) dipyridamole infusion protocol. CFR was defined as the ratio of peak hyperemic velocities to the baseline values. A reversible perfusion defect at LAD territory was accepted as a positive scintigraphy finding for significant LAD stenosis. A coronary angiography was performed within 5 days of the CFR studies. Results: The hyperemic diastolic peak velocity (44 ± 9 cm/sec vs 62 ± 2 cm/sec; P=0.01) and diastolic CFR (1.38 ± 0.17 vs 1.93 ± 0.3; P=0.001) were significantly lower in patients with LAD stenosis compared to those without LAD stenosis. The diastolic CFR values of <1.6 yielded a sensitivity of 100% and a specificity of 94% in the identification of significant LAD stenosis. In comparison, MPS detected LAD stenosis with a sensitivity of 100% and a specificity of 29%. Conclusions: CFR measurement by transthoracic Doppler echocardiography is an accurate method that may improve noninvasive identification of LAD stenosis in patients with LBBB.     

Black tea increases coronary flow velocity reserve in healthy male subjects

Epidemiologic studies suggest that tea consumption decreases the risk for cardiovascular events. However, there has been no clinical report examining the effects of tea consumption on coronary circulation. The purpose of this study was to evaluate the effects of black tea on coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography (TTDE). This was a double-blind crossover study of 10 healthy male volunteers conducted to compare the effects of black tea and caffeine on coronary circulation. The coronary flow velocity of the left anterior descending coronary artery was measured at baseline and at hyperemia during adenosine triphosphate infusion by TTDE to determine CFVR. The CFVR ratio was defined as the ratio of CFVR after beverage consumption to CFVR before beverage consumption. All data were divided into 2 groups according to beverage type: group T (black tea) and group C (caffeine). Two-way analysis of variance showed a significant group effect and interaction in CFVR before and after beverage consumption (p = 0.001). CFVR significantly increased after tea consumption in group T (4.5 +/- 0.9 vs 5.2 +/- 0.9, p <0.0001). The CFVR ratio of group T was larger than that of group C (1.18 +/- 0.07 vs 1.04 +/- 0.08, p = 0.002). Acute black tea consumption improves coronary vessel function, as determined by CFVR.     

Coronary Artery Imaging with Transthoracic Doppler Echocardiography

Coronary artery imaging with transthoracic Doppler echocardiography is a simple and useful technique to diagnose significant coronary artery stenosis. The visualization of mosaic flow in the proximal left coronary artery provides a direct indication of the presence of significant stenosis at the corresponding site during routine echocardiography. Coronary flow velocity reserve (CFVR) has a high diagnostic accuracy and feasibility in detecting the presence of functionally significant coronary stenosis in the left anterior descending coronary artery (LAD) and in the right coronary artery. The measurement of CFVR in the LAD also provides prognostic information in patients with intermediate coronary stenosis. This review summarizes the utility of transthoracic coronary artery imaging.     

Optimum hypoglycemic therapy can improve coronary flow velocity reserve in diabetic patients: demonstration by transthoracic doppler echocardiography.

The purpose of this study was to determine whether the elimination or the alleviation of hyperglycemia would improve coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography (TTDE). CFVR was measured by TTDE in the left anterior descending coronary artery in 49 poorly controlled diabetic patients before and after antidiabetic treatment and 15 well controlled diabetic patients also underwent the same measurements. The fasting blood glucose level in the poorly controlled patients reduced from 270 +/-106 mg/dl to 116+/-39 mg/dl at 20+/-15 days after the intensive treatment. Although baseline coronary flow velocity (CFV) did not change between the 2 measurements (19.9+/-6.9 cm/s vs 19.0+/-5.4 cm/s, p=NS), the hyperemic CFV increased significantly after the treatment (47.3+/-13.4 cm/s vs 55.4+/-13.2 cm/s, p<0.001). Thus, the CFVR improved significantly after the treatment (2.47+/-0.55 vs 2.98+/-0.56, p<0.001). Although there was minimal improvement in the control group (2.37+/-0.38 vs 2.50+/-0.37, p<0.05), the improvement in CFVR was significantly greater in the poorly controlled patients with intensive treatment (0.51+/-0.33 vs 0.12+/-0.19, p<0.001) than that in the control group. These results suggest that optimal hypoglycemic therapy is important to improve the CFVR in poorly controlled diabetic patients.     

Usefulness of coronary flow velocity measurement by transthoracic Doppler echocardiography in patients with acute coronary syndrome

OBJECTIVES: To evaluate the usefulness of left anterior descending coronary artery (LAD) flow measured by transthoracic Doppler echocardiography (TTDE) in patients with acute coronary syndrome. METHODS: Thirty consecutive patients with acute coronary syndrome in the LAD territory and unstable angina or non-ST-segment elevation myocardial infarction required decisions on the need for emergency coronary angiography. The diastolic peak flow velocity was measured in the distal segment of the LAD under guidance of color Doppler echocardiography in the emergency room. If LAD flow was not detected within 10 min, the coronary flow was judged as under the detection limit. The results of TTDE were compared with the Thrombolysis in Myocardial Infarction (TIMI) grade of LAD determined by coronary angiography, which was performed within 1 week (mean 2.5 +/- 1.5 days) in all patients. RESULTS: Coronary flow was not detected by TTDE in six patients who had TIMI grade 1 or 0. The diastolic peak flow velocity in 19 patients with TIMI 3 was higher than that in 5 patients with TIMI 2 (20.1 +/- 4.1 vs 10.9 +/- 2.3 cm/sec, p = 0.0001). A diastolic peak flow velocity of 14 cm/sec was the optimal cut-off value for the prediction of TIMI 3, with a sensitivity of 95% and a specificity of 100%. CONCLUSIONS: Coronary flow velocity measured by TTDE closely reflected the TIMI grade. Coronary flow measurement by TTDE is useful to decide the treatment strategy for patients with acute coronary syndrome in the emergency room.     

Non-invasive assessment of coronary arterial tone using trans-thoracic Doppler echocardiography.

BACKGROUND: As coronary flow velocity (CFV) is inversely related to the luminal size that exists for the myocardial bed, the elevated arterial tone can be assessed as the higher flow velocity in the epicardial artery. We examined the usefulness of transthoracic Doppler echocardiography (TTDE) for the assessment of coronary arterial tone. METHODS AND RESULTS: A total of 32 patients underwent TTDE and angiography. The luminal diameter (LD) in the left anterior descending artery (LAD) was measured by using quantitative coronary angiography before and after nitroglycerin (NTG) administration. The ratio of post NTG LD to the control (LD(NTG/Pre)) was assessed as a standard parameter of coronary arterial tone. We also measured CFV and CFV reserve (CFVR) at the LAD by TTDE. We evaluated the change of CFV (CFV(NTG/Pre)) and CFVR (CFVR(NTG/Pre)) following NTG administration. The LD increased from 1.98+/-0.46 to 2.51+/-0.34 mm (p<0.001), while the CFV decreased from 23.9+/-10.0 to 16.3+/-5.6 cm/s (p<0.03), and the CFVR increased from 2.39+/-0.65 to 3.56+/-1.12 (p<0.001). There were significant correlations between CFV(NTG/Pre) and LD(NTG/Pre) (p<0.0001, R2 = 0.532), and between the CFVR(NTG/Pre) and LD(NTG/Pre) (p<0.0001, R2 = 0.715). CONCLUSION: TTDE can assess the coronary arterial tone by measuring the responses of CFV and CFVR to NTG administration.     

Assessment of intermediate stenosis in the left anterior descending coronary artery with contrast-enhanced transthoracic Doppler echocardiography

BACKGROUND: Visual or quantitative assessment of coronary angiography may not exactly predict the physiological significance of intermediate (40-70%) coronary stenosis. Coronary flow reserve is a well-established marker of the functional significance of coronary stenosis. OBJECTIVES: The aim of this study was to compare the coronary flow velocity reserve (CFVR) using contrast-enhanced transthoracic Doppler echocardiography (CE-TTDE) with thallium-201 imaging in assessment of intermediate lesions in the left anterior descending coronary artery (LAD). METHODS: A consecutive series of 50 patients with intermediate stenosis in the LAD underwent pharmacological stress thallium-201 imaging and CFVR measured by CE-TTDE. RESULTS: CFVR could be measured in 49 of 50 patients by the present method. A CFVR <2.0 predicted the presence of a stress thallium defect in 12 of 14 patients (agreement=90%, kappa=0.76, P < 0.001). The sensitivity and specificity of CFVR for stress thallium-201 results were 86 and 91%, respectively. In contrast, significant stenosis (>50% by diameter) showed fair agreement for stress thallium defects (agreement=59%, kappa=0.28, P < 0.05). CONCLUSIONS: In the evaluation of intermediate lesions in the LAD, CFVR as assessed by CE-TTDE could accurately predict the presence of ischemia on stress thallium imaging, whereas angiographic stenosis did not yield reliable results.     

Noninvasive coronary flow reserve assessed by transthoracic coronary Doppler ultrasound in patients with left anterior descending coronary artery stents

Noninvasive measurement of coronary flow reserve (CFR) (hyperemic/flow velocity ratio at rest) by transthoracic Doppler echocardiography showed normalization of flow in the left anterior descending (LAD) coronary artery early after stenting. We hypothesized that noninvasive CFR may reveal in-stent restenosis at follow-up. Therefore, we studied 134 patients, 0 to 72 months after successful proximal-middle LAD stenting, and 38 controls. LAD flow velocity was measured by transthoracic Doppler echocardiography during 90 seconds venous adenosine infusion (140 microg/kg/min). CFR was measured in diastole. According to angiography, patients who received stents were divided into 3 groups: group I, <50% LAD in-stent restenosis (n = 83); group II, nonsignificant (50% to 69%) LAD in-stent restenosis (n = 17); and group III, significant (> or = 70%) LAD in-stent restenosis (n = 34). LAD CFR was similar in group I and controls (2.90 +/- 0.58 vs 3.05 +/- 0.81; p = NS), it was slightly lower in group II (2.42 +/- 0.33) compared with controls and group I (p <0.001 vs both), and clearly abnormal (<2) in group III (1.38 +/- 0.48) compared with controls, and groups I and II (p <0.001). A CFR <2 had 91% sensitivity, 95% specificity, and 96% positive and 97% negative predictive values to detect significant stenosis in patients with LAD stents. Our data show that noninvasive Doppler assessment of CFR allows identification of significant LAD in-stent restenosis, based on a cut-off value of <2.     

Detection of patency of internal mammary artery grafts to the left anterior descending artery by transthoracic Doppler echocardiography

BACKGROUND: To determine whether a coronary artery bypass graft (CABG) is patent, we examined the flow of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE). PATIENTS AND METHODS: Eighty-seven patients with CABG (LIMA to distal LAD) were enrolled in the study. The flows from each subject were analyzed by three criteria: mosaic flow at the anastomosis site, distal anterograde flow (ante flow), and proximal retrograde flow (retro flow). RESULTS: On angiography, 79 grafts were patent and eight were not. TTDE study of 79 patent grafts demonstrated mosaic, ante, and retro flow in 63 (79.7%), 74 (93.7%), and 35 grafts (49.4%), respectively. The averaged diastolic peak velocity of ante flow was 26.3 +/- 11.0 cm/sec, significantly higher than that (4.8 +/- 7.1 cm/sec, P < or = 0.0001) in eight patients without patent grafts. These eight patients had no mosaic or retro flow and only three had ante flow. The accuracies to predict patency were 81.6%, 90.8%, and 49.4% for mosaic, ante, and retro flows, respectively. CONCLUSIONS: The existence of mosaic, retro, or sufficient ante flows strongly indicated the patency of LIMA to the LAD. When symptoms are possible to be derived from the occlusion of CABG to LAD, TTDE is a promising method to examine whether a LIMA to LAD bypass is patent.