Coronary flow velocity reserve measurement in three major coronary arteries using transthoracic Doppler echocardiography

BACKGROUND: Measurement of the coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) has been reported to be useful for the noninvasive assessment of significant coronary artery stenosis or myocardial ischemia. The purpose of this study was to evaluate the value of this method in three major coronary arteries for detecting myocardial ischemia in the clinical setting. METHODS: We studied 89 consecutive patients who were referred to our outpatient clinic because of chest pain. We measured CFVR using TTDE in three major coronary arteries. We defined CFVR<2.0 in at least one vessel as being positive for myocardial ischemia. The accuracy of CFVR measurements for detecting myocardial ischemia was determined in comparison with exercise thallium-201 (Tl-201) single photon emission computed tomography (SPECT) as a reference standard. RESULTS: CFVR in at least one vessel was successfully measured in 87 of 89 patients (98%). The sensitivity and specificity of CFVR<2.0 in at least one coronary vessel, in any of the coronary territories, was 86% and 89%, respectively. In terms of assessing myocardial ischemia in each coronary artery territory, the agreement between CFVR<2.0 and Tl-201 SPECT for the left anterior descending coronary artery, the posterior descending coronary artery, and the left circumflex coronary artery territories was 95%, 81%, and 73%, respectively. CONCLUSION: Noninvasive CFVR measurement by TTDE may be useful for detecting myocardial ischemia, as well as for identifying ischemic territories in the clinical setting.     

Measurement of coronary flow velocity with Doppler catheter: evaluation of coronary flow reserve in successful angioplasty

To assess the therapeutic effect of percutaneous transluminal coronary angioplasty (PTCA) on coronary flow reserve, coronary flow velocity (CFV) was measured with a Doppler catheter before and immediately after PTCA in 11 patients, who underwent elective PTCA for critical stenosis in proximal or mid portion of the left anterior descending artery (LAD). A Doppler catheter was positioned at the proximal portion of the LAD and the CFV was measured at rest and after intracoronary injection of 6 ml of contrast material (Iopamidol), 6 ml of saline or 3 mg of Isosorbide Dinitrate (ISDN). Peak to resting velocity ratio (PRVR) was calculated as an estimate of coronary flow reserve. Percent diameter stenosis (%S) was measured from cineangiogram. A translesional pressure gradient was obtained with an angioplasty catheter. These parameters measured in PTCA candidates were compared with those in 11 patients whose LAD had no critical stenosis. After PTCA, %S was decreased (94.2 +/- 1.4 vs 34.1 +/- 5.1%; mean +/- SEM). Pressure gradient was also decreased (59.5 +/- 4.9 vs. 25.1 +/- 3.3 mmHg). There was no difference between mean CFV at rest in patients before PTCA and that in patients without stenosis (4.52 +/- 0.63 vs. 5.46 +/- 0.61 cm/sec). By successful PTCA, CFV at rest was increased (7.39 +/- 1.32, p less than 0.05 vs. before PTCA). PRVRs in patients before PTCA were smaller than those in patients without stenosis (1.5 +/- 0.1, 1.4 +/- 0.1, 1.6 +/- 0.2 vs. 2.8 +/- 0.1, 2.5 +/- 0.2, 2.8 +/- 0.2, p less than 0.01; by contrast material, saline, ISDN, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

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)     

Quantitating coronary collateral flow velocity in patients during coronary angioplasty using a Doppler guidewire

Quantitation of coronary collateral flow in patients has been limited to angiographic techniques, which are subject to well-known methodologic limitations. The use of a Doppler-tipped angioplasty guidewire permits measurement of both antegrade and retrograde flow distal to totally or subtotally occluded vessels that may be supplied with acutely recruitable or angiographically mature collateral condults. Using coronary flow velocity as an indicator of collateral flow, retrograde flow velocity was quantitated in 17 patients. Mean collateral flow velocity was approximately 30% of normal postangioplasty antegrade flow velocity. The phasic pattern of collateral flow was highly variable, but the retrograde diastolic and systolic flow velocity integrals were 20% and 40% (respectively) of post-procedure antegrade flow velocity. Preliminary studies with pharmacologic stimulation of the contralateral supply artery suggests that collateral flow is not increased by intracoronary nitroglycerin (200 μg) or adenosine (12 μg), but may be markedly augmented during mechanical stimulation of balloon occlusion. These data represent the first in a series of quantitative observations on control of the coronary collateral circulation in humans. Future investigations using the Doppler Flowire (Cardiometrics) will enhance understanding of factors modulating ischemia through collateral supply.     

Transcranial Doppler sonography for blood flow velocity measurement during pharmacological tests

Transcranial Doppler sonography, using a 2 MHz pulsed Doppler system, is suitable for non-invasive continuous monitoring of middle cerebral artery blood flow velocity during pharmacological studies. Methodological problems, and factors affecting cerebral blood flow have to be discussed (vasomotor spontaneous changes, intracranial blood pressure, blood viscosity, heart rate, vascular risk factors, etc.). Arguing from a previous study in 28 subjects (11 healthy volunteers, 8 hypertensive patients, 9 patients with middle cerebral artery stenosis), showing the hypotensive action of Nifedipine, without significant decrease of cerebral blood flow in 83% of cases, we emphasize the advantages and limits of this new non-invasive method for cerebral blood flow monitoring.     

Coaxial laser energy delivery using a steerable catheter in canine coronary arteries

Intracoronary delivery of argon laser energy was studied in eight anesthetized mongrel dogs. A No. 4.5 French single lumen catheter, with steerable guidewire and an optical fiber, was introduced through a Judkins-type femoral-coronary guiding catheter into three left anterior descending and eight left circumflex coronary arteries. A total of 65 laser energy exposures were made coaxially at 24 sites in the 11 arteries. At five sites, angiographically evident arterial perforation occurred with the first laser exposure, while at seven sites multiple laser exposures were made without angiographically evident perforation. All eight dogs remained hemodynamically stable, and were electively killed 5 +/- 1 hours following the procedure. Sections of myocardium from territories supplied by treated arteries demonstrated minimal or no pathology in 10 cases, while one territory had a small zone of early myocardial necrosis. This study suggests that standard coronary artery catheterization techniques can be used to introduce and position a steerable guidewire and an optical fiber in canine coronary arteries. Laser energy can repeatedly be delivered coaxially. Short-term deleterious effects may be reduced or eliminated, and exposure of blood elements to argon laser energy does not appear to create debris.     

Percutaneous transluminal coronary angioplasty using a steerable guiding catheter: a new technique

A new type of steerable guiding catheter is described for use in percutaneous transluminal coronary angioplasty (PTCA). It is simple to use and externally steerable. The catheter incorporates a steering system by means of which the catheter tip can be made to assume the form of either a right or left Judkins catheter or to be fixed in any intermediate configuration, entirely through external manipulation. We used this new guiding catheter to perform PTCA on 15 patients. Single lesions were found in the left anterior descending branch in seven patients, in the right coronary artery in four, and in the circumflex artery in two, whereas stenosis of a coronary bypass graft was found in two patients. Angioplasty was successful in all cases. There were no complications, during either the procedure or the postoperative hospitalization. The steerable guiding catheter described here may prove useful for PTCA in cases where a conventional catheter cannot be placed accurately or in cases with multi-vessel coronary disease.     

Validation of a Doppler guide wire for intravascular measurement of coronary artery flow velocity.

BACKGROUND. An improved intravascular ultrasonic Doppler device could aid the clinical assessment of coronary hemodynamics. We evaluated a new device consisting of a 12-MHz piezoelectric transducer integrated onto the tip of a 0.018-in. flexible, steerable angioplasty guide wire. METHODS AND RESULTS. Doppler spectra were recorded in model tubes with pulsatile blood flow and in-line electromagnetic flowmeter. In four straight tubes (i.d., 0.79-4.76 mm), the time average of spectral peak velocity (APV) was linearly related to blood flow (QEMF) (r2 greater than or equal to 0.98 for each tube). A Doppler-derived quantitative flow estimate (QD) was calculated as the product of vessel cross-sectional area and mean velocity, with mean velocity estimated as 0.5 x APV. The slope of QD versus QEMF for the four tubes was near unity. APV was less accurate in a 7.94-mm straight tube and in tortuous segments. In four dogs, the left circumflex coronary artery (LCx) was perfused from the femoral artery via a cannula with in-line electromagnetic flowmeter. Good-quality signals were obtained in proximal and distal LCx vessels 3.3-1.2 mm in diameter. APV varied linearly with QEMF (r2 greater than or equal to 0.99 in the cannula, r2 = 0.93-0.99 in proximal LCx, and r2 = 0.86-0.99 in distal LCx). QD was calculated by quantitative angiography to determine proximal LCx diameter. For all dogs combined, the slope of QD versus QEMF was 0.95 in the cannula and 0.85 in the proximal LCx. CONCLUSIONS. The Doppler guide wire measures phasic flow velocity patterns and linearly tracks changes in flow rate in small, straight coronary arteries. It should facilitate measurement of phasic coronary flow velocity during coronary angiography and angioplasty.     

Effects of smoking on coronary blood flow velocity and coronary flow reserve assessed by transthoracic Doppler echocardiography

BACKGROUND: Smoking is a well-known risk factor for cardiovascular disease. Coronary blood flow velocity (CFV) can be measured directly with transthoracic Doppler echocardiography (TTDE) which is conducted immediately after smoking. PURPOSE: The purpose of this study was to evaluate the chronic and acute effects of smoking on coronary blood flow and coronary flow reserve (CFR) by the use of TTDE. METHODS: Healthy volunteers (11 smokers and 9 nonsmokers) with a mean age of 27 +/- 3 years were included. Smoking was abstained for at least 4 hours before the study. CFV was measured at the distal left anterior descending coronary artery by TTDE at baseline and during intravenous adenosine infusion (140 microg/kg per minute) in all participants. For smokers, CFV was measured immediately after consecutively smoking two cigarettes and during adenosine infusion. RESULTS: CFR and coronary vascular resistance index (CVRI) showed no significant difference between nonsmokers and smokers (CFR: 3.5 +/- 0.8 vs 3.6 +/- 0.6, P = ns, CVRI: 0.28 vs 0.28, P = ns) at baseline. CFR significantly decreased (3.6 +/- 0.6 to 2.8 +/- 0.7, P = 0.008) and CVRI markedly increased (0.28 to 0.35, P = 0.012) after smoking. CONCLUSION: After 4 hours of abstinence from smoking, CFR and CVRI in smokers were similar to those of nonsmokers. However, consecutively smoking two cigarettes acutely reduced CFR and increased CVRI. These findings suggested that smoking could reduce coronary blood flow immediately, even in healthy people.     

Measuring blood flow velocity in the coronary sinus with Doppler catheters]

Measurements of the coronary sinus blood flow velocity with Doppler catheters (Medtronic Floscan; Millar DC201) were performed to assess coronary flow reserve and significance of coronary artery stenosis. In seven patients with normal coronary angiogram coronary sinus blood flow velocity (Doppler catheters) and coronary sinus blood flow volume (thermodilution) were simultaneously recorded. Coronary flow reserve was calculated as the quotient of the peak flow velocity (peak flow volume) and resting flow velocity (resting flow volume) after infusion of 0.5 mg/kg dipyridamole intravenously. The correlation coefficient was r = 0.88. Coronary sinus blood flow velocity was measured in 31 patients at resting conditions and after injection of contrast media during coronary angiography. At resting conditions blood flow velocity was 3.6 +/- 1.5 cm/s (n = 31), 3.5 +/- 1.8 cm/s (n = 9; controls), and 3.6 +/- 1.1 cm/s (n = 9; significant stenosis of the left anterior descending; not significant). After injection of contrast media flow velocity amounted to 2.2-fold resting flow in controls and to 1.5-fold resting flow in patients with stenoses of the left anterior descending artery (p less than 0.01). Measurement of coronary sinus blood flow velocity with Doppler catheters is a valuable adjunct for determination of coronary flow reserve and for assessment of stenosis severity of the left anterior descending artery. Continuous on-line monitoring of phasic flow velocity provides important information of the myocardial perfusion, e.g., during angioplasty.     

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.     

Coronary artery blood flow velocity non-invasively measured using a vessel-tracking pulsed Doppler system

A newly-developed noninvasive method was used to measure left coronary blood flow during phantom experiments. Two techniques were used in which: (1) the sample position can always be set in a fluctuating vessel using a wall echo-tracking method with a phase-locked-loop, and (2) the Doppler reference signal was generated separately synchronous with the wall echo signal. These techniques were combined, using a commercially available pulsed Doppler apparatus (SSH-40B: Toshiba). Basic experiments were performed using a blood vessel phantom to verify the validity of these systems. Blood flow velocity in the fluctuating tube could be measured clearly using a vessel-tracking method. The blood flow velocity of the left anterior descending artery was measured in three normal subjects and in seven patients from the third intercostal space along the left sternal border. The velocity pattern was characterized by a crescendo-decrescendo shape in diastole. The peak velocity which appeared in diastole ranged from 19 to 69 cm/sec, with no difference by disease entity. However, in all cases, the blood flow velocity signals were marred by extraneous signals, making it impossible to measure blood flow velocity during systole. Further improvement of the system is mandatory in order to use this flowmeter clinically.     

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.     

Doppler measurement of phasic continuous left ventricular blood flow velocity during ventricular arrhythmias

Phasic instantaneous left ventricular blood velocity was continuously measured by means of the Doppler ultrasonic flowmeter catheter radiotelemetry system in 68 patients with ventricular arrhythmias. Ventricular premature depolarizations reduced peak left ventricular blood velocities in relation to their respective coupling intervals, with R-R intervals less than 0.5 second producing the greatest decline. Ventricular tachycardia in 18 subjects produced a 62 per cent mean decrease in left ventricular blood velocity. In a single subject, performance of the Valsalva maneuver effected ventricular tachycardia and a concomitant marked diminution of phasic left ventricular blood velocity. These findings demonstrate the untoward influence of ventricular extrasystoles and tachycardia on left ventricular blood velocity and provide the underlying basis for reductions of blood velocity previously demonstrated in the regional circulations of man during similar arrhythmias.     

Real-time coronary blood flow measurement in patients with atrial fibrillation: a study using a catheter-tip Doppler velocimeter]

To clarify the influence of changes in the cardiac cycle length (R-R) and aortic pressure on the coronary blood flow, a catheter-tip Doppler velocimeter was applied for 16 patients with chronic atrial fibrillation (11 with valvular heart disease, 2 with coronary artery disease, 2 with cardiomyopathy and one with atrial septal defect). An area under the coronary flow velocity curve during systole (integral of S), diastole (integral of D) and one cardiac cycle (integral of T) for the proximal portion of the left anterior descending artery (LAD: 12 cases) or the right coronary artery (RCA: 10 cases) was calculated in beat-by-beat. Then, the correlations between each area and the R-R, systolic period (S), diastolic period (D) and aortic pressure were assessed. In both the LAD and RCA, prolongation of R-R associated with prolonged D increased integral of D, which caused an increase of integral of T. Integral of D correlated with D (p < 0.05), but integral of S did not correlate with S, and the degree of change in integral of S or S was much less than that in integral of D or D. R-R or D of the preceding beat correlated inversely (p < 0.05) with integral S in 11 of 12 LAD cases. In the RCA, positive correlations between R-R or D of the preceding beat and integral of S were observed in cases with mitral stenosis (n = 6) or coronary heart disease (n = 1), but not in other cases; a case with aortic regurgitation or hypertrophic cardiomyopathy, negative, and dilated cardiomyopathy, no correlation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of the human coronary circulation using a Doppler catheter

Arteriographic estimates of stenosis severity can fail to reflect the impact of an individual stenosis on delivery of blood to the myocardium. Whether a coronary stenosis is truly flow-limiting can be determined by measuring hyperemic blood flow or coronary flow reserve; however, until recently, the tools needed to measure coronary flow reserve in humans--namely, a method of quantitating coronary blood flow in individual arteries and another method for producing maximal microvascular vasodilation--were not available. Over the last 8 years, our laboratory group has developed a catheter for measuring coronary blood flow velocity in humans, using the Doppler principle, and studied the effects of microvascular vasodilators. These studies have enabled us to measure coronary flow reserve in humans and to characterize some of the effects of focal and diffuse atherosclerosis on the coronary circulation. In addition, we have used flow reserve measurements in the diagnosis of microvascular dysfunction in patients with chest pain and normal coronary arteries and as a means of assessing noninvasive methods for detecting focal coronary artery disease.     

不同多普勒取样容积对血流速度测量的影响

为探讨脉冲波多普勒不同取样容积（ＳＶ）对最大血流速度（Ｖｍａｘ）测量的影响，我们用内径５．０ｍｍ模拟血管和肝素化人全血，分别以不同血泵流率和ＳＶ为１．５ｍｍ，５．０ｍｍ及１０．０ｍｍ，在仪器其它条件不变的情况下，进行体外模拟脉动血流速度频谱实验。当流率为２００ｍｌ／ｍｉｎ至５００ｍｌ／ｍｉｎ时，ＳＶ为１．５ｍｍ与ＳＶ为５．０ｍｍ和１０．０ｍｍ所测多普勒频谱的Ｖｍａｘ值间差异显著（Ｐ＜０．０１），而ＳＶ为５．０ｍｍ与ＳＶ为１０．０ｍｍｒ测值间差异不显著（Ｐ＞０．０５）。提示在临床工作中，根据所测血管内径，尽可能增大ＳＶ长度，以减少通过时间效应所致频谱增宽，更能准确获得血流速度信息。     

Differentiation of abnormal blood flow patterns in coronary arteries based on Doppler catheter recordings

Abnormal arterial blood flow patterns have been implicated as etiologic factors in thrombosis and atherosclerosis. Intravascular pulsed Doppler ultrasound techniques with fast-Fourier transform analysis offer the opportunity to measure these abnormalities. The authors hypothesized that statistical analysis of radial-directed beam spectra could be used to distinguish disturbed from non-disturbed flow and that analysis of conventional axial-directed beam spectra could then be used to distinguish laminar high-shear from laminar low-shear flow. They developed a scaled-up in-vitro model of coronary flow consisting of a glycerol/H2O test fluid flowing through an acrylic cylinder at Reynolds numbers spanning the typical physiologic range within the coronary arteries. A scaled-up Doppler catheter with the capacity for 90 degrees reflection of the beam was placed centrally. Disturbed flow was created by introducing a flow screen, and altered shear rates were produced by changing the Reynolds number. For the radial-directed beam studies, the coefficients of variation of the Doppler spectra for the disturbed flow states were significantly greater than for the nondisturbed flow states (p less than 0.01). For the axial-directed beam studies, the coefficients of variation of the Doppler spectra for the laminar high-shear flow states were significantly greater than for the laminar low-shear flow states (p less than 0.01). They conclude that abnormal blood flow patterns can be differentiated by the selective use of radial-directed and axial-directed Doppler catheter recordings.