Noninvasive measurement of coronary artery blood flow using combined two-dimensional and Doppler echocardiography

Noninvasive measurement of left anterior descending coronary artery flow was attempted in 20 normal subjects and 80 patients with cardiovascular disease (valvular heart disease in 34, ischemic heart disease in 26, cardiomyopathy in 15 and other diseases in 5) using combined two-dimensional and Doppler echocardiography. A tubular structure about 2 mm in diameter containing Doppler flow signals was identified in the anterior interventricular sulcus in 7 (35%) of the normal subjects and 40 (50%) of the patients with cardiovascular disease. The blood flow within the tubular structure exhibited a biphasic flow pattern, consisting of systolic and diastolic phases with higher velocity during diastole. The highest velocities were observed in early diastole and, in several cases, a small peak was detected during the atrial contraction phase. On the basis of its spatial orientation and characteristic flow pattern, the tubular structure was identified as the midportion of the left anterior descending coronary artery. In a number of cases it was difficult to detect the systolic blood flow. Although blood flow was normally directed from the cardiac base to the apex, it was reversed toward the base in the patients with a bypass graft to the left anterior descending coronary artery. In patients with severe aortic insufficiency, however, flow velocity was lower during diastole than during systole and the duration of diastolic flow was reduced, failing to continue to the end of diastole. Flow velocity was high in patients with a bypass graft to the left anterior descending coronary artery, aortic stenosis or hypertrophic cardiomyopathy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of left internal mammary artery graft patency by transthoracic Doppler echocardiography

BACKGROUND: The successful application of noninvasive Doppler spectrum analysis has been reported for the hemodynamic assessment of LIMA graft after myocardial revascularization. HYPOTHESIS: The objective of this study was to assess the utility of transthoracic Doppler echocardiography (TTE) in providing information on LIMA flow in patients after coronary artery bypass graft surgery. METHODS: In all, 22 patients (aged 62 +/- 8 years) with LIMA graft to the left anterior descending (LAD) coronary artery who underwent coronary angiography were assessed using high-frequency (5 MHz) transthoracic Doppler echocardiography. They were compared with 25 patients with angina (control group A, aged 59 +/- 12 years), in whom an ungrafted LIMA was assessed, and with 17 patients (control group B, aged 59 +/- 9 years) with angiographically normal coronary arteries, in whom the LAD was assessed. RESULTS: A biphasic pattern (systolic and diastolic) was recorded in all cases. In 14 patients with a normal graft or < 70% stenosis (Group 1) and in control group B, blood flow was maximal during diastole. In eight patients with severe graft stenosis > 70% (Group 2) and control group B, blood flow was maximal during systole, with low diastolic flow. The diastolic fraction of the velocity time integrals was 0.81 +/- 0.11 for Group 1 and 0.25 +/-0.06 for Group 2 (p < 0.05). A diastolic velocity time integral fraction < 0.5 predicted > 70% stenosis with a sensitivity and specificity of 100%. The ratio of systolic/diastolic peak velocities was 0.61 +/- 0.31 for Group 1 and 3.21 +/- 0.49 for Group 2 (p < 0.05). A systolic/diastolic peak velocity > 1 predicted stenosis > 70% with a sensitivity and specificity of 100 and 90%, respectively. CONCLUSIONS: High-frequency TTE is a useful noninvasive method for detecting LIMA graft blood flow. Severe graft stenoses exhibited Doppler velocity patterns, which were different from those of patent grafts, or grafts with moderate stenoses.     

Effects of intraaortic balloon pumping on septal arterial blood flow velocity waveform during severe left main coronary artery stenosis

Objectives. We sought to evaluate the effect of intraaortic balloon pumping on the phasic blood velocity waveform into myocardium with severe coronary artery stenosis.Background. In the presence of severe coronary artery stenosis, it is not clear whether intraaortic balloon pumping augments intramyocardial inflow during diastole or changes systolic retrograde blood flow from the myocardium to the extramural coronary arteries.Methods. Using anesthetized open chest dogs (n = 7), we introduced severe stenosis in the left main coronary artery to reduce the poststenotic pressure to approximately 60 mm Hg (>90% diameter stenosis). Septal arterial blood flow velocities were measured with a 20-MHz, 80-channel ultrasound pulsed Doppler velocimeter. Left anterior descending arterial flow, aortic pressure and poststenotic distal coronary pressure were measured simultaneously. The diastolic anterograde flow integral and systolic retrograde flow integral were compared in the presence and absence of intraaortic balloon pumping.Results. Although intraaortic balloon pumping augmented diastolic aortic pressure, this pressure increase was not effectively transmitted through stenosis. Septal arterial diastolic flow velocity was not augmented, and left anterior descending arterial flow was unchanged during intraaortic balloon pumping.Conclusions. In the presence of severe coronary artery stenosis, intraaortic balloon pumping failed to increase diastolic inflow to the myocardium and did not enhance systolic retrograde flow from the myocardium to the extramural coronary artery. Thus, the major effect of intraaortic balloon pumping on the ischemic heart with severe coronary artery stenosis may be achieved by reducing oxygen demand by systolic unloading.     

Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty.

BACKGROUND AND OBJECTIVES. Studies using Doppler catheters to assess blood flow velocity and vasodilator reserve in proximal coronary arteries have failed to demonstrate significant improvement immediately after coronary angioplasty. Measurement of blood flow velocity, flow reserve and phasic diastolic/systolic velocity ratio performed distal to a coronary stenosis may provide important information concerning the physiologic significance of coronary artery stenosis. This study was designed to measure these blood flow velocity variables both proximal and distal to a significant coronary artery stenosis in patients undergoing coronary angioplasty. METHODS. A low profile (0.018-in.) (0.046-cm) Doppler angioplasty guide wire capable of providing spectral flow velocity data was used to measure blood flow velocity, flow reserve and diastolic/systolic velocity ratio both proximal and distal to left anterior descending or left circumflex coronary artery stenosis. These measurements were made in 38 patients undergoing coronary angioplasty and in 12 patients without significant coronary artery disease. RESULTS. Significant improvement in mean time average peak velocity was noted in distal coronary arteries after angioplasty (before 19 +/- 12 cm/s; after 35 +/- 16 cm/s; p less than 0.01). Increases in proximal average peak velocity after angioplasty were less remarkable (before 34 +/- 18 cm/s; after 41 +/- 14 cm/s; p = 0.04). Mean flow reserve remained unchanged after angioplasty both proximal (1.5 +/- 0.5 vs. 1.6 +/- 1; p greater than 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p greater than 0.10) to a coronary stenosis. Before angioplasty, mean diastolic/systolic velocity ratio measured distal to a significant stenosis was decreased compared with that in normal vessels (1.3 +/- 0.5 vs. 1.8 +/- 0.5; p less than 0.01). After angioplasty, distal abnormal phasic velocity patterns generally returned to normal, with a significant increase in mean diastolic/systolic velocity ratio (1.3 +/- 0.5 vs. 1.9 +/- 0.6; p less than 0.01). Phasic velocity patterns and mean diastolic/systolic velocity ratio measured proximal to a coronary stenosis were not statistically different from values in normal vessels (1.8 +/- 0.8 vs. 1.8 +/- 0.5; p greater than 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p greater than 0.10). CONCLUSIONS. Flow velocity measurements may be performed distal to a coronary stenosis with the Doppler guide wire. Phasic velocity measurements made proximal to a coronary stenosis differed from those in the distal coronary artery. Both proximal and distal flow reserve measurements made immediately after angioplasty were of limited utility. Changes in distal flow velocity patterns and diastolic/systolic velocity ratio appeared to be more relevant than the hyperemic response in assessing the immediate physiologic outcome of coronary angioplasty.     

Yield of transthoracic echocardiography with high frequency transducer in the study of the anterior descending coronary artery

INTRODUCTION AND OBJECTIVES: This study was performed to evaluate the feasibility and utility of a transthoracic high frequency transducer to detect and measure the left anterior descending coronary artery flow in patients with lesions in this artery or anterior myocardial infarction. MATERIALS AND METHODS: We studied 11 subjects with lesions greater than 75% and another 10 with anterior myocardial infarction. We compared the results with a control group of 18 subjects. An ATL HDI 5000 ultrasound unit with a 5-8 MHz transducer was used to identify the left anterior descending in the anterior interventricular sulcus from an apical four chamber window. We considered that left anterior descending was detected when a diastolic predominant flow pattern was obtained with pulse Doppler. RESULTS: Left anterior descending was detected in 37/39 of cases (94.4%). Patients with coronary lesions showed a decrease in the limit of significance in the diastolic/systolic peak velocity ratios: 2.5 (SD 0.7) vs 1.8 (SD 0.3) with a p = 0.024. Patients with anterior myocardial infarction obtained lower diastolic/systolic peak velocity ratios than controls: 2.5 (SD 0.7) vs 1.4 (SD 0.3) with a p = 0.001. CONCLUSIONS: Left anterior descending coronary artery flow can be assessed by transthoracic high frequency echocardiography in greater than 90% of the cases. Patients with coronary lesions and those with anterior myocardial infarction have a decreased diastolic/systolic peak velocity ratio.     

经皮冠状动脉内多普勒超声技术对冠状动脉血液动力学的研究

目的 :评价冠状动脉 (冠脉 )内多普勒血流钢丝测量冠脉血流速度和血流储备 (CFR)的应用价值。　　方法 :在 2 1例冠脉狭窄患者 (冠脉狭窄组 )和 12例正常冠脉者 (对照组 )中 ,利用冠脉内多普勒血流钢丝和冠脉内注射罂粟碱测量了冠脉的血流速度和 CFR。　　结果 :左前降支冠脉狭窄远端的平均最大血流速度、舒张期最大血流速度、舒张期与收缩期流速比值和 CFR均显著低于对照组测值。　　结论 :应用冠脉内多普勒超声技术可准确测量正常和冠脉狭窄患者的冠脉血流速度和 CFR,冠脉内注射罂粟碱安全、可靠 ,这一方法的临床应用对冠心病患者冠脉血液动力学的评价提供了可靠的方法。     

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.     

经胸多普勒超声冠状动脉血流储备检查诊断左前降支显著狭窄

目的比较经胸多普勒超声冠状动脉血流储备（CFR）指标诊断左前降支（LAD）显著狭窄的临床价值。方法连续120例怀疑冠心病的患者于冠状动脉造影（CAG）前一天进行双嘧达莫（0．56mg／kg）负荷试验，测定LAD的CFR指标，包括收缩期最大冠状动脉血流储备（SCFRpeak）、收缩期平均冠状动脉血流储备（SCF Rmean）、收缩期流速时间积分储备（SCFRVTI）、舒张期最大冠状动脉血流储备（DCFRpeak）、舒张期平均冠状动脉血流储备（DCFRmean）和舒张期流速时间积分储备（DCFRVTI）。结果82例获得LAD血流频谱，按照CAG结果分为LAD显著狭窄组（A组，≥70％狭窄，n=16）和LAD非显著狭窄组（B组，〈70％狭窄，n=66）。A组患者各项CFR指标均显著低于B组。ROC曲线法分析显示，DCFRmean〈1．825诊断LAD显著狭窄的敏感性和特异性相对较高。结论经胸多普勒超声评价CFR有助于检出LAD显著狭窄，DCFRmean〈1．825是较好的判别指标。     

Profiles of coronary blood flow velocity in patients with aortic stenosis and the effect of valve replacement: a transthoracic echocardiographic study.

OBJECTIVE--To report the first non-invasive assessment by transthoracic Doppler echocardiography of coronary blood flow in patients with aortic stenosis and of the effects of valve replacement. DESIGN--High frequency transthoracic Doppler echocardiography was used to examine resting phasic flow in the left anterior descending coronary artery before and after replacement of the aortic valve in awake, unsedated patients with pure aortic stenosis and normal coronary arteries. SETTING--A tertiary referral cardiothoracic centre. METHODS--Eleven patients with pure aortic stenosis and normal coronary arteries (six men, five women, mean (range) age 69 (50-82) years), were studied the day before and 1 week after replacement of the aortic valve. These patients were selected from a cohort of 15 due to ease of imaging of the left anterior descending coronary artery. Seven had a history of angina. Haemodynamics, peak transvalvar aortic gradient, left ventricular mass index, ventricular dimensions, and profiles of coronary flow velocity were measured. Profiles of coronary flow velocity were also measured in a control population of 10 normal subjects (five men, five women, mean (range) age 58 (34-66) years). RESULTS--The control population showed forward flow throughout systole, but reversed early systolic flow (mean velocity 20.6 (3.6) cm/s) was seen in six patients with aortic stenosis. Only three of these patients had a clinical history of angina. Peak and mean systolic and diastolic forward flow velocities were not significantly different in the control group and in patients with aortic stenosis. The time from the start of systole to the onset of forward systolic flow was significantly longer in patients with aortic stenosis than in the control population (185 (8.5) v 85 (10) ms, p < 0.01). The time from the onset of diastolic flow to peak diastolic velocity was also significantly longer in the aortic stenosis group (146 (16) v 74 (13) ms, p < 0.01). These abnormalities in profiles of coronary flow were reversed by replacement of the aortic valve. There was no correlation between changes in flow profiles in patients with aortic stenosis and preoperative clinical history, transvalvar gradient, left ventricular mass index, or ventricular dimensions. CONCLUSIONS--Coronary flow profiles in patients with aortic stenosis were characterised by reversed early systolic flow and delayed forward systolic flow and attainment of peak diastolic velocity. Reversal of these abnormalities by replacement of the aortic valve may reflect altered left ventricular and aortic haemodynamics and contribute to the relief of angina when left ventricular hypertrophy persists. Further studies may correlate abnormalities of coronary flow with preoperative clinical and haemodynamic state.     

Non-invasive evaluation of coronary reserve. Assessment of coronary reserve in patients with coronary artery disease by transesophageal-Doppler echocardiography

We assessed coronary flow reserve using transesophageal Doppler echocardiography in patients with coronary artery disease. The study included 33 coronary artery disease patients who were undergoing coronary arteriography. The blood flow velocities of the left anterior descending artery before and after intravenous infusion (0.56 mg/min for 4 min) of dipyridamole were recorded using transesophageal Doppler echocardiography. Fourteen normal healthy individuals, matched for age, served as a control group. The index of coronary flow reserve, i.e. the ratio of dipyridamole to baseline maximum diastolic velocity, was calculated. Maximal coronary flow reserve in coronary artery disease patients was significantly lower than in the control group (1.4+/-0.2 vs. 2.8+/-0.3, P<0.001). The coronary artery disease patients were classified into three groups: Group A included 10 patients with <50% left anterior descending artery stenosis; Group B included seven patients with 50-69% left anterior descending artery stenosis; 16 patients with >70% left anterior descending artery stenosis constituted Group C. The maximum coronary flow reserve was significantly different for A vs. B and A vs. C. (A, 1.77+/-0.18; B, 1.51+/-0.1; C, 1.28+/-0.24). A strong and significant correlation was found between the maximum coronary flow reserve and the degree of proximal left anterior descending artery stenosis (r=0.78, P<0.001). Coronary artery disease patients without left anterior descending artery stenosis on the arteriogram exhibited lower maximum coronary flow reserve compared to the control subjects (1.78+/-0.19 vs. 2.8+/-0.3, P=0.000).     

Flow analysis of left internal thoracic artery in myocardial revascularization surgery using y graft

In order to evaluate the left internal thoracic artery flow pattern, when the vessel is used as a graft to supply the left coronary artery system, we evaluated flow by Doppler measurement, both at rest and under dobutamine stress. There were 2 groups of 20 patients each: group A patients received only a left internal thoracic artery graft to the left anterior descending artery, and group B patients received a pedicled left internal thoracic artery graft associated with a vein graft, which together supplied the left anterior descending artery and another branch of the left coronary artery. Angiography showed patent grafts in all patients from both groups. The following characteristics were evaluated: systolic flow, diastolic flow, total flow, total flow under stress/total flow at rest ratio, systolic peak velocity, diastolic peak velocity, and systolic peak velocity/diastolic peak velocity ratio. In group A, the total flow was 45.5 +/- 21.6 mL/min at rest and 68.3 +/- 32.9 mL/min under stress. In group B, the total flow was 98.2 +/- 50.4 mL/min at rest and 175.7 +/- 79.2 mL/min under stress. Comparison between groups showed a total flow increase in group B of 115.8% (P=0.0002) at rest and 157.2% (P <0.0001) under stress. The other characteristics were also statistically significant, except systolic flow, total flow under stress/total flow at rest ratio, and systolic peak velocity. Our results showed that the left internal thoracic artery sufficiently supplies regional myocardium at rest and during exercise (stress), demonstrating its great adaptability in response to demand.     

Angiographical and Doppler flow-derived parameters for assessment of coronary lesion severity and its relation to the result of exercise electrocardiography. DEBATE study group. Doppler Endpoints Balloon Angioplasty Trial Europe.

AIMS: Evaluation of angiographical and intracoronary Doppler-derived parameters of coronary stenosis severity. METHODS AND RESULTS: A total of 225 patients with one-vessel disease were studied before PTCA and at 6 months follow-up. Exercise electrocardiography was performed to document presence (n = 157) or absence (n = 138) of an ST segment shift (> or =0.1 mV). Intracoronary blood flow velocity analysis was performed to determine the proximal/distal flow velocity ratio, the distal diastolic/systolic flow velocity ratio and coronary flow velocity reserve. Receiver operator characteristic curves were calculated to assess the predictive value of these variables compared with the exercise test. The distal coronary flow velocity reserve demonstrated the best linear correlation for both percentage diameter stenosis and minimum lumen diameter (r = 0.67 and r = 0.66; P<0.01), compared to the diastolic/systolic flow velocity ratio (r = 0.19 and r = 0.14; P<0.01) and the proximal/distal flow velocity ratio (r = 0.03 and r = 0.07; not significant). The areas under the curve were 0. 84+/-0.02; 0.82+/-0.03 and 0.83+/-0.03 for diameter stenosis, minimum lumen diameter and coronary flow velocity reserve, respectively. Logistic regression analysis revealed that the percentage diameter stenosis or minimum lumen diameter and coronary flow velocity reserve were independent predictors for the result of stress testing. CONCLUSIONS: The distal coronary flow velocity reserve is the best intracoronary Doppler parameter for evaluation of coronary narrowings. Angiographical estimates of coronary lesion severity and distal coronary flow velocity reserve are good and independent predictors for the assessment of functional severity of coronary stenosis, emphasizing the complementary role of these parameters for clinical decision making.     

Which Variable of Stenosis Severity Best Describes the Significance of an Isolated Left Anterior Descending Coronary Artery Lesion?: Correlation Between Quantitative Coronary Angiography,Intracoronary Doppler Measurements and High Dose Dipyridamole Echocardiography

Objectives. This study sought to investigate the angiographic or intracoronary Doppler variables of stenosis severity that best correlate with the results of dipyridamole echocardiography.Background. Quantitative coronary angiography and intracoronary Doppler flow velocity assessments are the commonly used techniques for the objective identification of significant coronary artery stenosis.Methods. Thirty patients with an isolated lesion of the left anterior descending coronary artery (LAD) were studied by means of on-line quantitative coronary arteriography, intracoronary Doppler flow velocity measurements and dipyridamole echocardiography 6 months after percutaneous transluminal coronary angioplasty. The quantitative arteriographic analyses were performed on-line; post-stenotic Doppler flow velocities were measured at baseline and after adenosine infusion. Angiographic and Doppler measurements were compared with the corresponding dipyridamole echocardiographic data and analyzed by discriminant analysis.Results. The dipyridamole echocardiographic response was positive in 11 patients (37%). The best cutoff values for predicting an abnormal echocardiographic response were 1) stenotic flow reserve of 2.8 (p = 0.0001); 2) 59% diameter stenosis (p = 0.0001); 3) minimal lumen diameter of 1.35 mm (p = 0.001); 4) coronary flow reserve of 2.0 (p = 0.0002); and 5) maximal peak velocity of 60 cm/s during hyperemia (p = 0.04). Multivariate analysis identified stenotic flow reserve as the only independent predictor of ischemia during dipyridamole echocardiography.Conclusions. Stenotic flow reserve is the variable that best describes the functional significance of an isolated LAD lesion, and a value of 2.8 is the best predictor of a positive dipyridamole echocardiographic response. Furthermore, angiographic variables of stenosis severity relate to echocardiographic test results better than intracoronary Doppler variables.     

Effect of intracoronary nitroglycerin administration on phasic pattern and transmural distribution of flow during coronary artery stenosis.

BACKGROUND. Nitroglycerin is effective in relieving myocardial ischemia; however, intracoronary nitroglycerin often fails to relieve angina and has been reported to have deleterious effects on subendocardial blood flow. To understand the mechanisms involved, we evaluated the direct effect of nitroglycerin on coronary circulation of the ischemic hearts. METHODS AND RESULTS. We measured the phasic pattern of intramyocardial coronary arterial flow with an 80-channel, 20-MHz pulsed Doppler ultrasound flowmeter under moderate to severe coronary artery stenosis (distal perfusion pressure approximately 45 mm Hg group 1, n = 6) and transmyocardial blood flow distribution using radioactive microspheres while maintaining coronary pressure at a low constant level (40 mm Hg, group 2, n = 6). In anesthetized open-chest dogs, the left main coronary artery was perfused directly from the right carotid or femoral artery. In this bypass circuit, pressure was controlled with an occluder or a reservoir was connected to the circuit. In group 1, the systolic and diastolic pressures distal to the stenosis decreased significantly after intracoronary administration of nitroglycerin at maximal coronary flow from 66.5 +/- 18.5 to 56.5 +/- 13.8 mm Hg (p less than 0.01) and from 36.6 +/- 14.4 to 27.5 +/- 8.9 mm Hg (p less than 0.01), respectively. The phasic pattern of the septal artery flow was predominantly diastolic and was characterized by systolic reverse flow even in the absence of stenosis. Coronary stenosis increased systolic reverse flow. Nitroglycerin increased diastolic forward flow (p less than 0.05) but augmented systolic reverse flow markedly (p less than 0.001). In group 2, nitroglycerin increased subepicardial flow (p less than 0.05) but failed to increase subendocardial flow. With the administration of nitroglycerin, the subendocardial-to-subepicardial flow ratio decreased significantly from 0.73 +/- 0.19 to 0.32 +/- 0.14 (p less than 0.01). CONCLUSIONS. The increased systolic reverse flow after intracoronary administration of nitroglycerin may be closely related to failure of subendocardial blood flow to increase with increase subepicardial flow.     

Assessing myocardial perfusion with the transthoracic Doppler technique in patients with reperfused anterior myocardial infarction: comparison with angiographic, enzymatic and electrocardiographic indices.

AIMS: Doppler guidewire studies demonstrated that the no-reflow phenomenon in acute myocardial infarction is associated with characteristic coronary blood flow pattern. We investigated the potential of coronary flow measurement with transthoracic Doppler technique to detect the no-flow in the patients with reperfused infarction, and compared it to that of other modalities. METHODS AND RESULTS: We performed intracoronary myocardial contrast echocardiography after successful primary coronary intervention in the 94 patients with first, anterior wall infarction. Coronary blood flow in the left anterior descending artery was detected with transthoracic Doppler echocardiography within 24 h after reperfusion in 83 patients (88.3%). Twenty-two patients with the no-reflow had significantly lower systolic peak velocity (5.1 +/- 4.2 vs. 8.1 +/- 6.2 cm/s, p = 0.04), higher diastolic peak velocity (38.2 +/- 10.3 vs. 30.8 +/- 15.7 cm/s; p = 0.04), and shorter diastolic deceleration time (134 +/- 41 vs. 424 +/- 202 ms; p < 0.0001) than those with good-reflow. Systolic flow reversal was more frequently observed in those with no-reflow (18.2% vs. 3.3%, p = 0 .02). Diastolic deceleration time < 185 ms detected the no-reflow with far higher sensitivity/specificity (95.5%/95.1%) than TIMI frame count (45.5%/91.8%), ST resolution (54.5%/73.8%) and creatinine kinase-MB (54.5%/88.5%). CONCLUSION: Analysing coronary blood flow pattern can detect the no-reflow after anterior infarction better than other angiographic, electrocardiographic and enzymatic modalities.     

Evaluation of flow characteristics of the left internal thoracic artery graft: perioperative color Doppler ultrasonography versus intraoperative free-bleeding technique

From October 2000 through April 2001, we prospectively evaluated the flow characteristics of the left internal thoracic artery (LITA) graft in a homogenous group of 44 men with isolated severe proximal left anterior descending coronary artery stenosis who underwent elective coronary artery bypass grafting with cardiopulmonary bypass. We performed transthoracic color Doppler ultrasonography preoperatively and repeated this examination in each patient between the 5th and 7th postoperative days, obtaining cross-sectional area, total flow volume, diastolic velocity, systolic velocity, mean velocity, pulsatility index, and resistance index. These results were compared with those of the intraoperative free-bleeding technique. Good-quality Doppler images of the LITA were easily obtained with a combined supraclavicular-parasternal approach. After surgery, systolic flow velocity, pulsatility index, and resistance index decreased significantly, but diastolic flow velocity and mean flow velocity increased significantly. The intraoperative flow volume obtained by the free-bleeding technique (32.42 +/- 12.33 mL/min) was significantly less than both pre- and postoperative ultrasonographic values (42.22 +/- 10.77 mL/min and 45.36 +/- 19.52 mL/min, respectively). No significant difference was found when changes in LITA values were compared between patients with (n=19) and without (n=25) normal anterior wall motion. We conclude that color Doppler ultrasonography is a reliable noninvasive technique for preoperative evaluation of the LITA as a graft and for postoperative long-term follow-up of graft function. However the intraoperative free-bleeding technique is not reliable for flow-volume measurement due to anesthesia-related hemodynamic changes and vasospasm. Color Doppler can prevent useless LITA harvesting and decrease the need for postoperative LITA angiography.     

Effect of left ventricular hypertrophy secondary to systemic hypertension on left coronary artery flow dynamics.

STUDY OBJECTIVE--The aim was to clarify the characteristics of the phasic blood velocity pattern and their possible causes in left ventricular hypertrophy secondary to systemic hypertension. DESIGN--Measurements of blood velocities in the left anterior descending coronary artery were made with a 20 MHz Doppler catheter with a top mounted annular crystal. All patients had normal coronary arteriograms. PATIENTS--23 hypertensive patients [systolic/diastolic pressure: 181(SD 15)/100(4) mm Hg)] with left ventricular hypertrophy, and 13 atypical chest pain patients without left ventricular hypertrophy or any abnormal haemodynamic findings (normal controls) entered the study. MEASUREMENTS AND MAIN RESULTS--The left anterior descending coronary artery blood velocity waveform in pressure overloaded left ventricular hypertrophy was characterised by delayed early diastolic inflow. The diastolic rise time of coronary flow (TDR), ie, the time from the beginning of diastole to peak velocity, was higher in patients with hypertensive left ventricular hypertrophy than in normal controls, at 145(56) v 66(15) ms, p less than 0.001. In patients with hypertensive left ventricular hypertrophy, TDR correlated well with the degree of hypertrophy (r = 0.83, p less than 0.01) and also with peak left ventricular systolic pressure (r = 0.62, p less than 0.01). The coronary flow reserve, calculated from the ratio of the diastolic mean velocity after intracoronary injection of papaverine to the resting flow velocity, decreased with prolongation of TDR (r = 0.58, p less than 0.02). CONCLUSIONS--(1) Impairment of early diastolic coronary arterial inflow is the most remarkable characteristic in pressure overloaded left ventricular hypertrophy; (2) preceding systolic vascular compression and impaired left ventricular relaxation correlate with the delayed early diastolic inflow; (3) the delayed inflow is an important possible cause of the decreased coronary flow reserve in the hypertensive left ventricular hypertrophy.     

Comparison of the postoperative blood flow waveforms of the bypassing grafts in patients following minimally invasive direct coronary artery bypass

PURPOSE: To use Doppler ultrasound velocimetry to detect and compare the postoperative flow characteristics of the bypassing grafts in patients following minimally invasive direct coronary artery bypass surgery (MIDCAB). MATERIALS AND METHODS: From January 1997 to June 1999, 34 patients underwent MIDCAB with the left internal thoracic artery (LITA) to the left anterior descending coronary artery (LAD) [n = 23], with the right gastroepiploic artery (RGEA) to the right posterior descending artery (RPD) [n = 3], or with the LITA with a saphenous vein graft extension to the LAD (n = 6), the diagonal coronary artery (n = 1), or the right acute coronary artery (n = 1). There were two patients with LITA to the LAD and RGEA to the RPD. Patients underwent MIDCAB due to coronary artery stenosis (100% occlusion, n = 10; 90 to 99% stenosis, n = 18; < 90% stenosis, n = 5) or unsuccessful percutaneous transcoronary angioplasty with dissection (n = 1). All patients underwent flow velocity measurement by Doppler ultrasound velocimetry in the immediate postoperative period, and at 6-month and 12-month intervals; graft flows were quantified based on Doppler velocimetric data. RESULTS: The results showed that in a patient with a totally occluded LAD or RPD, typical biphasic velocity waveforms were consistently observed. However, a delayed diastolic wave was noted in RGEA grafts. In patients with less-occluded stenotic lesions or with strong back flows, the flow velocity patterns showed biphasic waveforms but systolic reversal was observed in the area closest to the anastomotic site. CONCLUSION: The presence of an LAD or RPD stenosis proximal to the anastomotic site significantly affects the LITA or RGEA graft flow volume. The biphasic flow pattern proves that an LITA or RGEA graft transports the blood primarily to coronary arteries during the diastolic phase.     

Comparison of transthoracic Doppler echocardiography to intracoronary Doppler guidewire measurements for assessment of coronary flow reserve in the left anterior descending artery for detection of restenosis after coronary angioplasty

Transthoracic Doppler echocardiography (TDE) has been described as a feasible and accurate technique to noninvasively assess coronary flow reserve (CFR) in the left anterior descending artery (LAD). This study was designed to evaluate whether serial assessment of CFR in the LAD using TDE allows detection of restenosis after previously performed angioplasty. Thirty-three consecutive patients with single-vessel coronary artery disease of the LAD scheduled for angioplasty underwent assessment of coronary flow velocity at rest and during adenosine-induced hyperemia in the distal LAD using high-frequency TDE. CFR was calculated as the ratio of hyperemic to basal systolic/diastolic mean velocity. Investigations were performed before and immediately after angioplasty, and at the time of control angiography after 3 months. CFR results by TDE were compared with intracoronary Doppler guide wire measurements. Adequate pulse-wave Doppler signals to measure CFR were obtained in 30 patients (91%) using TDE. There was close correlation between echocardiographically and intracoronary derived CFR results (r = 0.80, 0.79, and 0.87 before angioplasty, early after, and at 3- month control angiography, respectively; p <0.001). Using a cut-off value of CFR < or =2.0 to identify significant coronary artery disease, TDE detected LAD restenosis with a sensitivity of 89% and specificity of 90%. Thus, high-frequency TDE is a feasible technique to noninvasively assess CFR in the LAD with results closely corresponding to invasive measurements. Defining a cut-off value of CFR < or =2.0, the technique has the potential to reliably detect LAD stenosis after coronary intervention.     

Acute effect of atorvastatin on coronary circulation measured by transthoracic Doppler echocardiography in patients without coronary artery disease by angiography

Thirty-two patients were randomly assigned to treatment with placebo or atorvastatin. The time-averaged peak diastolic velocity (APDV) of the left anterior descending artery without stenosis was measured by transthoracic Doppler echocardiography at rest and under hyperemic conditions before and 1 hour after treatment. APDV increased significantly in the atorvastatin group, at rest and under hyperemic conditions, and coronary flow velocity reserve also increased in the atorvastatin group compared with patients given placebo. Atorvastatin improved the blood flow velocity of the normal coronary artery <1 hour after administration in patients without coronary artery disease by angiography.