Validation of a new noninvasive method (contrast-enhanced transthoracic second harmonic echo Doppler) for the evaluation of coronary flow reserve: comparison with intracoronary Doppler flow wire.

OBJECTIVES: We tested the hypothesis that coronary flow reserve (CFR) in the left anterior descending coronary artery (LAD) as assessed by a new noninvasive method (contrast-enhanced transthoracic second harmonic echo Doppler) is in agreement with CFR measurements assessed by intracoronary Doppler flow wire. BACKGROUND: Contrast-enhanced transthoracic second harmonic echo Doppler is a novel noninvasive method to detect blood flow velocity and reserve in the LAD. However, it has not yet been validated versus a gold-standard method. METHODS: Twenty-five patients undergoing CFR assessment in the LAD by Doppler flow wire were also evaluated by contrast-enhanced transthoracic Doppler to record blood flow in the distal LAD at rest and during hyperemia obtained by adenosine i.v. infusion. In five patients CFR was evaluated twice (before and after angioplasty). RESULTS: As a result of the combined use of i.v. contrast and second harmonic Doppler technology, feasibility in assessing coronary flow reserve equaled 100%. The agreement between the two methods was high. In fact, in all but five patients the maximum difference between the two CFR measurements was 0.38. Overall, the prediction (95%) interval of individual differences was -0.69 to +0.72. Reproducibility of CFR measurements was also high. The limits of the agreement (95%) between the two measurements were -0.32 to +0.32. CONCLUSIONS: Coronary flow reserve in the LAD as assessed by contrast-enhanced transthoracic echo Doppler along with harmonic mode concurs very closely with Doppler flow wire CFR measurements. This new noninvasive method allows feasible, reliable and reproducible assessment of CFR in the LAD.     

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)     

Estimation of coronary flow reserve by intracoronary Doppler flow probes and digital angiography

This prospective study investigated two different methods used clinically to estimate coronary flow reserve during cardiac catheterization. First, the relationship between simultaneous digital angiography and intracoronary Doppler velocity measurements was determined in 61 patients. The correlation coefficient for 233 simultaneous pairs of papaverine-induced flow reserve was 0.70 (Doppler = 0.41 digital + 0.93, P less than 0.0001). Repeated basal flow determinations showed little variability (Doppler: 2 +/- 5% (mean +/- 95% confidence intervals); digital: 3 +/- 10%). Repeated hyperemic flow estimates by the Doppler technique were more reproducible (10 +/- 2%) than those by the digital method (26 +/- 6%). Second, estimates of coronary flow reserve by side-mounted and end-mounted Doppler catheters were compared in vitro and in patients. In vitro measurement of blood velocity was linear for both catheter designs and was highly correlated with volume flow determined by electromagnetic flow meter (r = 0.99 side-mounted; r = 0.96 end-mounted). In patients (n = 20), average coronary flow reserve for the side-mounted Doppler crystal was 2.64 +/- 0.15 and for the end-mounted Doppler crystal was 2.40 +/- 0.14 (P less than 0.02). When flow reserve was determined twice for each catheter, there was greater variability in repeated measurements using the side-mounted Doppler crystal (21 +/- 10%, n = 14) than using the end-mounted Doppler crystal (12 +/- 4%, n = 32).(ABSTRACT TRUNCATED AT 250 WORDS)     

Value and limitations of intracoronary adenosine for the assessment of coronary flow reserve

An ideal coronary vasodilator for studying coronary flow reserve should rapidly produce a maximal hyperemic response, be short acting to permit repeated measurements, and not alter systemic hemodynamics. We measured with a Doppler tip balloon catheter, in 12 patients before and/or after percutaneous transluminal coronary angioplasty the hyperemic response following 12.5 mg intracoronary papaverine and following gradually incremental bolus injections of intracoronary adenosine, starting from 0.05 mg until a maximal hyperemic response or side effects. The mean dose (+/- SD) of adenosine needed to produce maximal hyperemia was 0.23 (+/- 0.20 mg). Coronary blood flow velocity after adenosine increased to 1.6 +/- 0.3 times resting coronary blood flow velocity, comparable in magnitude to the hyperemia following intracoronary papaverine. The time from injection to peak effect after adenosine was 7.4 (SD +/- 2.2) sec and after papaverine 26 (SD +/- 7) sec. Adenosine resulted in a bradyarrhythmia in three patients. Intracoronary adenosine is a potent and very short acting vasodilator for studying coronary flow reserve, but the side effects and unpredictability of the dosage needed to produce maximal hyperemia may limit its applicability.     

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.     

Contrast-enhanced transthoracic second harmonic echo Doppler with adenosine: a noninvasive, rapid and effective method for coronary flow reserve assessment.

OBJECTIVES: The purpose of this study is to evaluate the feasibility in detecting blood flow in the left anterior descending coronary artery (LAD) using transthoracic color Doppler (CD) imaging (in both second harmonic and fundamental mode) along with contrast enhancement and to verify if this new noninvasive method along with adenosine is safe, rapid and effective in assessing coronary flow reserve (CFR). BACKGROUND: Feasibility of contrast-enhanced transthoracic Doppler recording (in both second harmonic and fundamental mode) of blood flow velocity in the LAD has not been assessed. Adenosine has a greater vasodilator potency and more favorable kinetics than dipyridamole and thus it can be more suitable for assessing CFR in conjunction with this method. METHODS: Sixty-one patients with angiographically patent LAD underwent CD (both in fundamental and harmonic mode) as well as color-guided pulsed wave (PW) Doppler recording of blood flow velocity in the distal LAD before and after intravenous contrast injection. A second group of patients (n = 77), undergoing coronary angiography, was submitted to transthoracic contrast-enhanced PW Doppler recording of blood flow velocity in the LAD using harmonic CD as a guide, at rest and during adenosine-induced hyperemia. RESULTS: Harmonic CD along with echo contrast consistently improved blood flow detection in the LAD; the success rate in detecting flow of optimal quality was 88% with this approach, whereas it was 11% and 16% with CD in fundamental mode, respectively, before and after contrast. Pulsed wave Doppler results paralleled those of harmonic CD (p < 0.001 contrast harmonic vs. fundamental). In the second group of patients coronary angiography revealed 0% to <40% stenosis in 24 patients (group I), > or =40% to < or =75% in 17 patients (group II) and >75% stenosis in 34 patients (group III). There was a significant difference in CFR among the three groups of patients; CFR for peak diastolic velocity was (mean +/- SD): 2.88+/-0.7 (group I), 2.09+/-0.5 (group II) and 1.51+/-0.5 cm/s (group II) (p < 0.05 group I vs. both group II and group III; p < 0.05 group II vs. group III). The whole examination took less than 10 min. CONCLUSIONS: Contrast-enhanced second harmonic Doppler recording of blood velocity in the LAD is highly feasible and in combination with adenosine it is a rapid, safe and effective method for assessing CFR ratio.     

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.     

Simultaneous measurement of coronary flow reserve by left anterior descending coronary artery Doppler and great cardiac vein thermodilution methods.

OBJECTIVES. The objective of this study was to compare left anterior descending coronary artery Doppler blood flow velocity and great cardiac vein thermodilution blood flow measurements of coronary flow reserve and submaximal coronary vasodilation in humans. BACKGROUND. Reported maximal coronary flow reserve values obtained with the coronary venous thermodilution method are lower than those obtained with other measurement methods. METHODS. Thermodilution measurements of great cardiac vein flow in 11 subjects were compared with simultaneous Doppler measurements of changes in left anterior descending coronary flow velocity after intracoronary administration of papaverine, nitroglycerin, iohexol and intravenous administration of dipyridamole. RESULTS. Coronary flow reserve (papaverine peak/rest flow ratio) was 3.7 +/- 1.7 (mean +/- SD) by the Doppler method and 2.0 +/- 0.7 by the thermodilution technique (p less than 0.001). Thermodilution flow changes were also smaller than Doppler-measured changes during submaximal vasodilation and during prolonged coronary dilation after dipyridamole administration. CONCLUSIONS. Coronary flow reserve and submaximal flow increases measured with the thermodilution method were consistently and substantially smaller than Doppler-derived measurements. This discrepancy has important implications for the comparison of coronary flow reserve measurements performed with the use of different techniques.     

Physiologic assessment of coronary artery stenosis by coronary flow reserve measurements with transthoracic Doppler echocardiography: comparison with exercise thallium-201 single piston emission computed tomography

OBJECTIVES: We evaluated the value of coronary flow reserve (CFR), as determined by transthoracic Doppler echocardiography (TTDE), for physiologic assessment of coronary artery stenosis severity, and we compared TTDE measurements with those obtained by exercise thallium-201 (Tl-201) single-photon emission computed tomography (SPECT). BACKGROUND: Coronary flow reserve measurements by TTDE have been reported to be useful for assessing angiographic left anterior descending coronary artery (LAD) stenosis. However, discrepancies exist between angiographic and physiologic estimates of coronary lesion severity. METHODS: We studied 36 patients suspected of having coronary artery disease. The flow velocity in the distal LAD was measured by TTDE both at rest and during intravenous infusion of adenosine. Coronary flow reserve was calculated as the ratio of hyperemic to basal peak (peak CFR) and mean (mean CFR) diastolic flow velocities. The CFR measurements by TTDE were compared with the results of Tl-201-SPECT. RESULTS: Complete TTDE data were acquired for 33 of 36 study patients. Of these 33 patients, Tl-201-SPECT confirmed reversible perfusion defects in the LAD territories in 12 patients (group A). Twenty-one patients had normal perfusion in the LAD territories (group B). Peak CFR and mean CFR (mean value +/- SD) were 1.5 +/- 0.6 and 1.5 +/- 0.7 in group A and 2.8 +/- 0.8 and 2.7 +/- 0.7 in group B, respectively. Both peak and mean CFR < or = 2.0 predicted reversible perfusion defects, with a sensitivity and specificity of 92% and 90%, respectively. CONCLUSIONS: Noninvasive measurement of CFR by TTDE provides data equivalent to those obtained by Tl-201-SPECT for physiologic estimation of the severity of LAD stenosis.     

Noninvasive assessment of coronary flow reserve in the left anterior descending artery by transthoracic echocardiography before and after stenting

BACKGROUND: Noninvasive assessment of coronary flow reserve in the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE) has been already validated as a new method for determining the degree of stenosis over the proximal flow. OBJECTIVES: The aim of the study is to determine, by TTDE, the feasibility and the value of the coronary flow reserve (CFR) (defined as the maximal increase in coronary blood flow above its basal pressure for a given perfusion pressure when coronary circulation is maximally dilated) in the mid-to-distal LAD before and after percutaneous angioplasty and to demonstrate the early recovery of microvascular tone immediately after stenting. METHODS: The study population consisted of 36 patients with significant isolated LAD stenosis (70-90%) identified by coronary angiography. CFR was recorded in the mid-to-distal LAD at rest and during hyperemia obtained after adenosine intravenous infusion before and after stenting. RESULTS: Adequate visualization of the LAD was obtained in 25 out of 36 patients (70%). At rest the mean CFR was 1.5132 +/- 0.33 (1.1-2.58). However, after stenting the mean CFR was significantly higher: 2.18 +/- 0.55 (1.3-3.8), with P <0.01. CONCLUSIONS: CFR can be easily determined by TTE in approximately 70% of patients. Noninvasive Doppler echocardiography shows impaired CFR in patients with LAD disease. After stenting CFR is restored, demonstrating early recovery of microvascular tone. These results are comparable to those published in the same conditions. Larger series with a long-term follow-up may allow identifying patients at high risk for restenosis after stenting.     

Assessing coronary blood flow dynamics with the TIMI frame count method: comparison with simultaneous intracoronary Doppler and ultrasound.

This study compared the TIMI frame count (TFC), which has been proposed as a method for quantifying coronary blood flow, with coronary flow and microvascular function measured with intracoronary Doppler and intracoronary ultrasound. Coronary blood flow volume was calculated from coronary blood velocity (by intracoronary Doppler) and lumen area (by intracoronary ultrasound) in the LAD in 46 post-heart transplant patients at baseline and after intracoronary adenosine. TFC correlated significantly with average peak coronary blood velocity (r = -0.42; P = 0.004) and coronary lumen area (r = 0.39; P = 0.008), but not with coronary blood flow volume (r = -0.01; P = 0.96) or the coronary flow reserve response to adenosine (r = 0.09; P = 0.58). In conclusion, TFC is a simple method of assessing coronary blood velocity but not volumetric flow. While TFC does not predict coronary flow reserve, as a measure of velocity it does provide an assessment of basal microvascular tone, information that is complementary to that afforded by flow reserve measurements.     

Second harmonic imaging of an intravenously administered echocardiographic contrast agent: Visualization of coronary arteries and measurement of coronary blood flow

Objectives. This study sought to evaluate the potential of second harmonic contrast echocardiography to assess coronary vasculature.Background. Newer transpulmonary ultrasound contrast agents capable of resonance phenomena detected by harmonic imaging may theoretically be able to demonstrate blood flow in the myocardium.Methods. Transthoracic B-mode images and Doppler were obtained using a prototype second harmonic ultrasound system after femoral vein injection of AFO145 (10 to 40 mg) in 13 closed chest dogs (mean weight 25.6 kg). Coronary Doppler flow was simultaneously invasively measured using an intracoronary flow wire and visually compared with transthoracic Doppler flow. “Noninvasive” coronary vasodilator reserve was determined by measuring the ratio of the Doppler time velocity integral after adenosine to the baseline value and compared with the “invasive” intracoronary determination.Results. Harmonic imaging showed heterogeneous opacification of the myocardium characterized by linear branching structures consistent with intramyocardial coronary arteries, which were not clearly visible during conventional ultrasound imaging. In nine dogs, transthoracic Doppler was performed, and characteristic coronary Doppler flow was observed, identical to the simultaneously observed intracoronary Doppler flow. Intracoronary adenosine (120 to 150 μg) equally increased intracoronary and transthoracic Doppler flow velocities. The calculated “noninvasive” and “invasive” coronary vasodilator reserve ratios were similar ([mean ± SD] 3.3 ± 1.0 and 3.6 ± 1.2, p = NS), with excellent correlation (r = 0.95, p = 0.0012).Conclusions. These findings indicate that noninvasive assessment of intramyocardial coronary vasculature and measurement of coronary blood flow reserve are possible using second harmonic contrast echocardiography.     

Impaired coronary flow reserve immediately after coronary angioplasty in patients with acute myocardial infarction.

OBJECTIVE--To examine coronary flow reserve immediately after emergency coronary angioplasty in patients with acute myocardial infarction. DESIGN--A 3 F coronary Doppler catheter was used to measure coronary blood flow velocity in the infarct artery and in the non-infarct artery. Maximal hyperaemia was produced by 10 mg of intracoronary papaverine and coronary flow reserve was calculated. PATIENTS--11 patients with acute myocardial infarction undergoing both emergency coronary angioplasty (4.7 (3.6) h after the onset of chest pain (mean (SD))) and at follow up catheterisation 16 (4) days after angioplasty. SETTING--Hiroshima City Hospital. RESULTS--There was no stenosis of > or = 50% in the coronary artery of interest. Immediately after coronary angioplasty the mean (1 SD) coronary flow reserve of the infarct artery was significantly less than that of the non-infarct artery (1.4 (0.4) v 2.8 (0.8), p < 0.001). At follow up catheterisation the coronary flow reserve of the infarct artery increased almost to the value of the non-infarct artery (2.8 (1.2) v 3.1 (0.8) p = NS). CONCLUSION--The coronary flow reserve in the infarct region was severely impaired immediately after reperfusion, even with a widely patent infarct artery. This could restrict the beneficial effects of reperfusion therapy, especially when there is a severe residual stenosis.     

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.     

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.     

Abnormal vasomotor function of the epicardial coronary arteries in children five to eight years after arterial switch operation: an angiographic and intracoronary Doppler flow wire study.

OBJECTIVES: This study sought to test the vasoreactivity of the translocated coronary arteries after arterial switch operation (ASO) using quantitative angiographic analysis and intracoronary Doppler flow wire velocimetry. BACKGROUND: Late coronary artery events occur in 3% to 8% of patients after the ASO. Previous studies of coronary flow reserve have yielded disparate results. METHODS: Nineteen children previously underwent ASO (13 boys, age 5.4 +/- 3.2 years, weight 22.3 +/- 10.6 kg), and six control patients were enrolled in the study. Each patient underwent quantitative angiographic assessment of the epicardial coronary arteries before and after administration of nitroglycerin and coronary blood flow volume assessment before and after administration of adenosine and acetylcholine. The results were compared between groups. RESULTS: Epicardial coronary artery dilation in response to intracoronary nitroglycerin was significantly less in the ASO group than in the control group (left anterior descending [LAD], 5.0 +/- 0.05% vs. 18.0 +/- 4.5%, p = 0.0009; right coronary artery [RCA], 4.0 +/- 0.07% vs. 32.7 +/- 12.7%, p = 0.006). Moreover, the coronary blood flow volume reserve was reduced in ASO patients compared with control patients after intracoronary infusion of acetylcholine (2.3 +/- 0.9 vs. 4.9 +/- 1.7, p = 0.0003) or adenosine (2.7 +/- 1.5 vs. 5 +/- 0.5, p = 0.002). CONCLUSIONS: Epicardial coronary arteries fail to dilate normally in children after ASO, and the calculated coronary flow volume reserve is consequently reduced.     

Flow velocity and predictors of a suboptimal coronary flow velocity reserve after coronary balloon angioplasty.

AIMS: This study was conducted to analyse flow velocity parameters and predictors of a suboptimal coronary flow reserve (<2.5) following balloon angioplasty. METHODS: Two hundred and twenty-five patients underwent sequential intracoronary Doppler as part of the DEBATE I study. Of these, 183, with complete angiography and Doppler at the 6-month follow-up, were included. Univariate and multivariate logistic analysis was performed to identify independent predictors of post-procedural suboptimal coronary flow reserve, defined as coronary flow reserve <2.5. RESULTS: Forty-eight per cent (n=88) of the patients achieved a suboptimal coronary flow reserve. These patients had higher baseline velocities (cm.s(-1)) before balloon angioplasty (18+/-9 vs 14+/-6, P=0.004), after balloon angioplasty (22+/-11 vs 14+/-5, P<0.001) and at follow-up (19+/-9 vs 16+/-6, P=0.011) than the optimal coronary flow reserve group. Although the suboptimal group had lower hyperaemic velocities (cm.s(-1)) after balloon angioplasty than the optimal group (42+/-17 vs 49+/-16, P=0.008), these velocities became similar at follow-up. Increasing age (odds ratio, OR 1.071, P=0.0002), female gender (OR 2.52, P=0.014) and increasing pre-procedural baseline average peak velocities (OR 1.056, P<0.001) were found to be independent predictors of a suboptimal coronary flow reserve following balloon angioplasty. CONCLUSION: A suboptimal coronary flow reserve was associated with (1) a chronically elevated baseline average peak velocity (2) a transient deficit in the hyperaemic average peak velocity (3) the elderly, and female gender.     

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.     

Coronary Doppler intensity changes during handgrip: a new method to detect coronary vasomotor tone in coronary artery disease.

OBJECTIVES: This study evaluates whether a quantitative measurement of Doppler intensity during handgrip may disclose coronary vasomotor dysfunction in patients with coronary artery disease (CAD). BACKGROUND: Atherosclerotic coronary segments show an exaggerated constrictive response to handgrip. The intensity of the scattered Doppler signal is proportional to the number of blood cells flowing through the vessel, and should be reduced during vasoconstriction. Therefore, changes in coronary flow during handgrip may be detected by measuring Doppler intensity rather than velocities. METHODS: The distal left anterior descending coronary artery (LAD) was imaged by high-resolution transthoracic color Doppler echocardiography during handgrip in 47 patients: 15 with normal coronary arteries and 32 with significant CAD involving the LAD. The Doppler signal was acquired at 70 dB dynamic range at baseline, 30-s handgrip and 5 min recovery. Peak and mean flow velocity, pressure half-time, deceleration time (ms), deceleration rate (cm/s2) and mean gray level intensity (intensity units [IU]) of the Doppler spectrum were measured in diastole. RESULTS The velocity parameters did not change significantly during handgrip both in normal and CAD patients. The Doppler intensity significantly decreased during handgrip (from 87.0 +/- 32.8 to 57.7 +/- 35.3 IU; p < 0.001) in patients with CAD, and it increased or remained unchanged in normals (from 74.1 +/- 27.3 to 85.1 +/- 31.2 IU; p = NS). The sensitivity of Doppler intensity in detecting CAD was 84.4%, specificity 93.3%, negative predictive value 73.7% and positive predictive value 96.4%. CONCLUSIONS: Doppler intensity measured by transthoracic echocardiography during handgrip allows the detection of CAD and coronary vasomotor dysfunction.     

A simplified method to measure coronary blood flow velocity in patients: validation and application of a Judkins-style Doppler-tipped angiographic catheter

To facilitate more rapid and safe measurement of coronary flow velocity reserve in patients, we developed a Judkins-style angiographic catheter tipped with a 20 MHz Doppler crystal. In 19 patients without coronary artery disease, resting and hyperemic (10 mg intracoronary papaverine) mean and phasic coronary flow velocity signals were measured with the Judkins-style and 2.5F intracoronary Doppler catheters at identical coronary loci. Mean coronary flow velocity at rest was similar (14 +/- 8, 10 +/- 7 cm/sec, p = ns), but was higher during hyperemia for the Judkins-Doppler (41 +/- 8 versus 32 +/- 14 cm/sec, p less than 0.05). Coronary flow velocity reserve, calculated as the ratio of mean velocity at rest to mean velocity following papaverine, was 3.3 +/- 1.4 and 3.7 +/- 1.2 units (p = ns) for the Judkins and intracoronary Doppler techniques, respectively (r = 0.801, p less than 0.001). The Judkins-style Doppler catheter technique permits flow velocity and coronary flow velocity reserve measurements that correlate strongly with those of the intracoronary catheter technique, facilitating safe, quick, and accurate assessment of coronary physiology.