Simple detection of severe coronary stenosis using transthoracic doppler echocardiography at rest

Differences in coronary artery blood velocities in the setting of normal coronary angiography and normal stress echocardiography

Background

Normal left anterior descending (LAD) coronary artery as determined by coronary angiography is considered not only to reflect normal angiography but also to correlate with normal anatomy and function. However, subjects who undergo coronary angiography may differ from those who do not need to have invasive evaluation even if their functional noninvasive studies like dobutamine stress echocardiography (DSE) were normal.

Aim

LAD velocities in subjects with normal angiography and those with normal DSE are equal.

Methods

A total of 244 subjects were evaluated, 78 had normal LAD by angiography and 166 had normal LAD by DSE. All had Doppler sampling of LAD velocities by transthoracic echocardiography.

Results

Velocity was higher in the angiographic subgroup in diastole 41 ± 23 vs 33 ± 14 cm/s, p = 0.0078; systole 18 ± 14 vs 13 ± 7 cm/s, p = 0.012; diastolic integral 12.6 ± 5 vs 9.8 ± 3.8 cm, p = 3.15 × 10^-5; systolic velocity integral 4 ± 2.9 vs 2.8 ± 1.9, p = 0.0014. While heart rate was similar in both groups, the product of diastolic velocity integral and heart rate of the LAD in the angiographic group was higher: 902 ± 450 vs 656 ± 394, p = 0.00599. Diastolic velocity deceleration time was similar in both groups. Coronary flow reserve defined as diastolic velocity ratio before and immediately after DSE correlated negatively with baseline velocity, r = -0.4.

Conclusions

Mode of defining normality of coronary artery affects velocity behavior of the vessel, reflecting functional differences possibly related to microvasculature and vasodilatation.

Acceleration time of systolic coronary flow velocity to diagnose coronary stenosis in patients with microvascular dysfunction

BACKGROUND

The aim of this study was to test whether acceleration time of systolic coronary flow velocity could contribute to the diagnosis of coronary stenosis in patients with microvascular dysfunction, on the basis of the hypothesis that systolic coronary flow is less influenced by microvascular function because of compressed myocardium.

METHODS

Coronary flow velocity was assessed in the left anterior descending coronary artery during hyperemia with intravenous adenosine by echocardiography in 502 patients who were scheduled for coronary angiography because of coronary artery disease and significant valvular disease. Coronary flow velocity reserve (CFVR) and the percentage acceleration time (%AT), as the percentage of the time from the beginning to the peak of systolic coronary flow over systolic time during hyperemia, were calculated. The diagnostic ability of CFVR and %AT for angiographic coronary artery stenosis was then analyzed. As invasive substudies, fractional flow reserve and %AT by a dual-sensor (pressure and Doppler velocity) guidewire were measured simultaneously with %AT on transthoracic echocardiography (n = 14).

RESULTS

Patients with coronary stenosis had significantly lower CFVR (1.7 ± 0.4) and greater %AT (65 ± 9%) compared with those without stenosis (2.6 ± 0.6 and 50 ± 13%, respectively). Percentage acceleration time by Doppler echocardiography was in good agreement with %AT (r = 0.98) and fractional flow reserve (r = 0.74) invasively measured by dual-sensor guidewire. Cutoff values of CFVR and %AT were determined as 2.0 and 60% in receiver operating characteristic curve analysis. The sensitivity, specificity, and accuracy of CFVR to detect coronary stenosis were 71.1%, 77.3%, and 75.4%, while those of %AT were 83.4%, 71.8%, and 75.4%, respectively. In addition, %AT provided high accuracy to detect coronary stenosis, especially in patients with previous myocardial infarctions, valvular disease, and left ventricular hypertrophy (81.1%, 84.1%, and 73.4%, respectively).

CONCLUSIONS

The %AT of systolic coronary flow velocity is a promising marker to diagnose coronary stenosis in patients with microvascular dysfunction.

[Interest of coronary flow reserve of the LAD during dobutamine stress echocardiography]

AIM OF THE STUDY

To assess the value of the coronary flow reserve (CFR) in the left anterior descending artery (LAD) during dobutamine stress echocardiography in the diagnosis of significant LAD stenosis (more than 70%).

METHOD

Retrospective study of 81 patients with a positive stress echocardiography who underwent a coronarography.

RESULTS

Measurement of coronary flow reserve was able in half echocardiographic exams. Medium Pic diastolic velocity was 0.33 m/s (SD 0.20), medium maximal diastolic velocity during stress was 0.62 m/s (SD 0.20), medium CFR was 2.25 (SD 0.65). In 50 patients LAD was not seen; in five of them LAD was occluded. The predictive positive value (PPV) of a low coronary flow reserve to detect LAD stenosis is 66.7% and the negative predictive value (NPV) is 65.4%. An abnormal anterior contraction during stress echo with a low reserve has a PPV of 75% for the diagnosis of significant IVA stenosis and a normal contraction during stress with normal coronary flow reserve means a NPV of 65%. We did not show a significant correlation between low coronary flow and abnormal contraction during stress echocardiography (kappa 0.51).

CONCLUSION

Coronary flow reserve of LAD during stress echo is feasible but does not really improve exam performance to detect significant IVA stenosis. This measurement remains to be clear in coronary patients management.

Coronary Flow Reserve of the Non-Ischemia Related Coronary Artery During Dobutamine Stress Echocardiography

Background

Incorporation of analysis of coronary velocities in stress studies adds diagnostic value to both clinical variables and dobutamine echocardiography. Micorcirculatory abnormalities may precede obstructive corornary disease. Therefore the aim of this study was to assess Doppler derived coronary velocity and flow of the left anterior descending coronary artery (LAD) during dobutamine stress echocardiography (DSE) in patients without LAD-related ischemia.

Methods

Sixty nine patients with chest pain underwent DSE studies to evaluate myocardial ischemia. All had trans-thoracic Doppler interrogation of the distal LAD before and just after termination of the DSE. Coronary velocity reserves (CFR) were calculated as the ratios of post-DSE/baseline diastolic velocities. Volumetric flow in the distal LAD was calculated from the diameter of LAD color jet and velocity integral. Volumetric flow reserve was calculated as the ratio of post-DSE baseline LAD flows.

Results

At rest all subjects had left ventricular wall motion score index (WMSI) = 1, while in 28, wall motion abnormality appeared in non-LAD territory with WMSI = 1.17 ± 0.08. Peak diastolic velocity after DSE increased form 28.5 ± 13.6 to 52.4 ± 23.7 cm/sec, P = 9.5 × 10^-11, and velocity-CFR was 2.08 ± 0.7. Diastolic LAD flow increased from 36.5 ± 23.8 to 75.75 ± 48.7 mL/min, P = 1.21 × 10^-7 and volumetric-CFR was 2.6 ± 2.8. Peak diastolic velocity-CFR in patients without LV wall motion abnormality was 2.4 ± 0.7 while in those with motion abnormality 1.77 ± 0.56, P = 0.00008. Flow-derived LAD-CFR was 3.3 ± 3.7 in those without compared to 1.88 ± 0.57 in patients with wall motion abnormality, P < 0.05.

Conclusion

LAD velocity and flow reserves are reduced in patients with remote myocardial ischemia, which may indicate early atherosclerotic involvement.

Detection of severe left anterior descending coronary artery stenosis by transthoracic evaluation of resting coronary flow velocity dynamics

In the presence of severe stenosis, coronary artery flow may be reduced at rest. Recent advances in echocardiography have made non-invasive sampling of velocities in the left anterior descending coronary artery (LAD) possible. The aim of our study was to evaluate feasibility and capability of transthoracic Doppler to detect severe stenosis of the LAD. The study population consisted of 42 subjects with suspected coronary artery disease scheduled for coronary angiography. All had complete transthoracic echocardiography and Doppler sampling of LAD velocities. Quantitative coronary angiography was performed within 24 hours of the echocardiogram. Correlations between LAD velocity profile, measurements and calculations, and the angiographic results were performed. Six subjects had LAD occlusion, 10 had severe (>80% diameter) LAD stenosis, and 26 had normal or non-occlusive LAD disease. In all six subjects with LAD occlusion, distal LAD velocities were not detectable, while in the other 36 subjects, LAD velocities were recorded indicating the vessels were patent. In the 10 subjects with severe LAD stenosis, the diastolic/systolic velocity ratio was <1.5, while in those with non-significant LAD disease, the diastolic/systolic velocity ratio was >1.5 (P<0.005). Diastolic LAD flow was 21.8±13 mL/min in the presence of severe stenosis as compared to 48.5±20 mL/min in subjects without severe stenosis (P<0.0013). LAD velocities had high sensitivity and specificity for the prediction of severe angiographic stenosis. Thus transthoracic Doppler measurement of LAD velocities is feasible and can predict the presence of severe LAD stenosis or occlusion.

Detection of severe stenosis and total occlusion in the left anterior descending coronary artery with transthoracic Doppler echocardiography in the emergency room

BACKGROUND

The noninvasive measurement of coronary flow velocity in the left anterior descending artery (LAD) has recently been realized by using the transthoracic Doppler echocardiography (TTDE). A couple of investigations demonstrated that the diastolic-to-systolic peak velocity ratio (DSVR) by TTDE is a simple and noninvasive method for the detection of severe stenosis in the elective settings. However, the usefulness of DSVR by TTDE in the emergency settings has not been evaluated.

OBJECTIVE

The purpose of this study was to assess the clinical feasibility to document the LAD flow by TTDE in emergency patients who complained of chest pain.

METHODS

We studied 49 consecutive patients with acute coronary syndrome who were going to undergo emergency coronary angiography (CAG) for the anatomical diagnosis and the facilitated percutaneous coronary intervention (PCI). Prior to CAG, we recorded the LAD flow by TTDE and measured the diastolic peak velocity (DVp), systolic peak velocity (SVp), and their ratio, DSVR (DVp/SVp) of LAD flow.

RESULTS

By CAG, the culprit lesions actually resided in the proximal LAD in 36 patients. Among the 36 patients, we detected the Doppler LAD flow in 29. Five out of 7 patients who were unable to detect the LAD flow revealed total occlusions by CAG. DSVR of the LAD is significantly lower in 17 patients who showed severe stenoses (>90%) than those in the rest of 12 patients who did not show such critical stenoses (1.44 +/- 0.16 vs 2.10 +/- 0.26, P < 0.0001).

CONCLUSION

In the emergency settings, a noninvasive assessment of the LAD flow by TTDE accurately estimates the critical stenotic lesions of the LAD.

Non-invasive assessment of coronary flow and coronary flow reserve by transthoracic Doppler echocardiography: a magic tool for the real world

Transthoracic Doppler echocardiography, introduced in the echo-lab in recent last years, to measure coronary flow and coronary flow reserve, is a very attractive tool, totally non-invasive, and easily available at bedside. This review summarizes the actual possibilities of this tool, its multiple potential clinical applications and diagnostic insights, and its arising prognosis value, in coronary artery disease as in various settings affecting the coronary microcirculation.

Ultrasonographic assessment of basal coronary flow as a screening tool to exclude significant left anterior descending coronary artery stenosis

OBJECTIVE

Coronary blood flow exhibits a biphasic pattern at rest with a higher diastolic and a smaller systolic component. In the present investigation, we evaluated whether a decreased diastolic to systolic velocity ratio of basal coronary flow may be useful in the identification of subjects with significant left anterior descending coronary artery (LAD) stenosis.

METHODS

One hundred and twenty-nine consecutive patients (62 with unstable angina, 25 with acute myocardial infarction and 42 with chronic coronary artery disease) were included in the study. Blood flow velocities were recorded in the mid-distal portion of the LAD using an ATL 5000 CV HDI ultrasound system. All patients underwent coronary angiography and were divided into two groups according to the absence (group 1) or the presence (group 2) of significant LAD stenosis (lumen narrowing > or = 70%). In 60 of the 129 patients, coronary flow reserve was evaluated non-invasively.

RESULTS

Adequate Doppler recordings in the LAD were obtained by transthoracic echocardiography in 113 patients. There were no differences between groups with regard to sex, cardiovascular risk factors, left ventricular mass and volumes, ejection fraction, whereas the diastolic to systolic velocity ratio of basal coronary flow was significantly lower in group 2 patients (1.41 +/- 4.7 vs. 2.08 +/- 0.64, P < 0.00001). The receiver operating characteristic curve showed that a diastolic to systolic velocity ratio < 1.6 had a sensitivity of 77%, a specificity of 91%, a positive predictive value of 77%, a negative predictive value of 97%, and a diagnostic accuracy of 84% for the presence of significant LAD stenosis. In 55/60 patients, results of basal coronary flow and coronary flow reserve were concordant. On multivariate logistic regression analysis, the diastolic to systolic velocity ratio was a strong independent predictor of LAD stenosis > or = 70% (odds ratio 4.90, 95% confidence interval 1.65-7.30).

CONCLUSIONS

The present findings suggest that assessment of basal coronary flow in the LAD may be useful to rule out the presence of significant stenosis.

Noninvasive diagnosis of ischemic and nonischemic cardiomyopathy using coronary flow velocity measurements of the left anterior descending coronary artery by transthoracic Doppler echocardiography

OBJECTIVES

The purpose of this study was to assess the feasibility and usefulness of coronary flow velocity measurements of the left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography (TTDE) to differentiate ischemic cardiomyopathy (ICM) from non-ICM in patients.

BACKGROUND

ICM and non-ICM have similar 2-dimensional echocardiographic features, left ventricular dilatation, and diffuse wall-motion abnormalities. TTDE may be useful to differentiate ICM from non-ICM by detecting significant LAD stenosis based on LAD flow signal analysis.

METHODS

TTDE was performed in 52 consecutive patients with left ventricular dilatation and diffuse wall-motion abnormalities of unknown origin. Peak and averaged systolic and diastolic flow velocities of the distal LAD flow could be recorded and measured from 44 patients (85%). Peak and mean diastolic/systolic velocity ratio (DSVR) were calculated.

RESULTS

By coronary angiogram, 13 patients were given the diagnosis of ICM and 31 of non-ICM. Left ventricular end-diastolic and end-systolic volumes and ejection fraction were similar between ICM and non-ICM. On the other hand, peak DSVR (1.47 +/- 0.38 vs 2.34 +/- 0.67, P < .0001) and mean DSVR (1.40 +/- 0.42 vs 2.24 +/- 0.61, P < .0001) were significantly lower in patients with ICM than non-ICM. Either peak DSVR less than 1.8 or mean DSVR less than 1.8 had a sensitivity of 77% and a specificity of 77% for detecting the presence of severe LAD stenosis and, therefore, the diagnosis of ICM.

CONCLUSION

TTDE is a useful noninvasive method to differentiate ICM from non-ICM.

Evaluation of Left Anterior Descending Coronary Artery Stenosis of Intermediate Severity Using Transthoracic Coronary Flow Reserve and Dobutamine Stress Echocardiography

BACKGROUND

The physiologic significance of left anterior descending coronary artery (LAD) stenosis of intermediate angiographic severity is of clinical importance and difficult to assess. Assessment of coronary flow reserve (CFR) by Doppler transthoracic echocardiography (TTE) is a new tool and could allow rapid, noninvasive evaluation of stenosis severity in this setting.

OBJECTIVE

We sought to evaluate the value of CFR measurement determined by TTE, compared with dobutamine stress echocardiography (DSE), in the setting of LAD stenosis of intermediate angiographic severity.

METHODS

A total of 51 consecutive stable patients in sinus rhythm (33 men; age 65 +/- 12 years; left ventricular ejection fraction 59 +/- 7%) with no previous anterior myocardial infarction and with an angiographic proximal LAD stenosis of intermediate severity (56 +/- 8% quantitative coronary angioplasty) were prospectively studied. Coronary flow velocity was measured in the distal part of the LAD by TTE at rest and during continuous infusion of 0.14 mg/kg/min of adenosine over 2 minutes, using a multifrequency transducer, in the modified parasternal or 3-apical view. CFR was calculated as the ratio of hyperemic to basal mean (mean CFR) and peak (peak CFR) diastolic flow velocity. DSE was performed immediately after the adenosine test to assess ischemia in the LAD territory (percent maximum predicted heart rate = 94 +/- 8).

RESULTS

Adequate recording of CFR was possible in 46 patients. Of the 35 patients with a CFR of 2 or more (peak CFR = 2.7 +/- 0.6), DSE was normal in 34. Of the 11 patients with a CFR less than 2 (peak CFR = 1.7 +/- 0.2), 7 had an abnormal response with DSE in the LAD territory. In this range of intermediate stenosis, there was a poor correlation between percent LAD diameter stenosis and CFR. For patients with positive DSE, CFR was 1.6 +/- 0.2 compared with 2.7 +/- 0.6 for patients with normal DSE (P < .05). The sensitivity, specificity, and the positive and negative predictive values of TTE CFR for detecting ischemia on DSE were 88%, 89%, 64%, and 97%, respectively, with an overall agreement of 89% between the two tests.

CONCLUSION

Given its high negative predictive value, noninvasive CFR could be a useful aid in reaching clinical decisions promptly at the bedside in patients with moderately severe lesions of the proximal LAD.

Physiologic Assessment of Coronary Artery Stenosis without Stress Tests: Noninvasive Analysis of Phasic Flow Characteristics by Transthoracic Doppler Echocardiography

We evaluated the significance of the diastolic-to-systolic blood flow velocity ratio (DSVR) determined by transthoracic Doppler echocardiography, for a physiologic assessment of the severity of coronary stenosis without stress tests, as compared with thallium 201 single photon emission computed tomography. In 95 patients undergoing thallium 201 single photon emission computed tomography for coronary artery disease, the flow velocity in the distal left anterior descending coronary artery was obtained with transthoracic Doppler echocardiography. The mean and peak DSVR values were calculated using mean and peak coronary flow velocity. DSVR was successfully measured for 82 patients (86.3%), including 33 patients with reversible perfusion defects in the left anterior descending coronary artery territories. For predicting reversible perfusion defects in thallium 201 single photon emission computed tomography, the best cut-off points were 1.5 for mean DSVR (sensitivity 81.8%, specificity 85.7%) and 1.6 for peak DSVR (sensitivity 75.7%, specificity 83.6%). Noninvasive measurement of DSVR with transthoracic Doppler echocardiography provides physiologic estimation of the left anterior descending coronary artery stenosis severity at high success rate, without stress tests.

Impact of ostial stenosis on the Doppler flow profiles in internal thoracic artery graft

As ostial stenoses of internal thoracic artery (ITA) grafts rarely occur after coronary artery bypass grafting, little is known about their Doppler flow profile. This report describes changes in the Doppler flow of ITA grafts with ostial stenosis after surgical repair of the stenosis. A 54-year-old male underwent coronary artery bypass grafting (CABG) in which the left ITA was anastomosed to the left anterior descending coronary artery. The follow-up coronary angiography revealed an ostial 90% stenosis of the ITA. The patient underwent elective surgery during which the radial artery was interposed between the left subclavian artery and the ITA. Intraoperative ultrasonography was performed immediately before cut down of the ITA graft and again immediately after completion of all anastomoses. Both diastolic and systolic velocities and the velocity time integral increased more than 2-fold after the repair. Neither the diastolic-to-systolic peak velocity ratio nor the diastolic velocity time integral fraction showed remarkable change. These profiles were different from those reported previously for distal stenosis.

[Measurement of coronary flow and flow reserve with transthoracic echocardiography: an old concept, a new tool, a lot of applications]

Non invasive evaluation of coronary flow and flow reserve by using transthoracic echocardiography is a promising method for evaluating coronary disease. Left anterior descending and right posterior descending coronary flow are accessible in the majority of patients. This technique is useful in various settings: detection of coronary artery stenosis, coronary occlusion, follow up after percutaneous coronary intervention, evaluation of the significance of coronary stenosis of intermediate severity, evaluation of the microcirculation, study of reperfusion and no reflow in the acute phase of myocardial infarction, evaluation of bypass grafts, improvement of the diagnostic accuracy during stress echocardiography. After a period of training, it's possible to change an old concept, formerly not easily accessible in clinical practice, into a useful and modern tool for evaluating coronary artery disease.

Changes in left anterior descending coronary artery flow profiles after coronary artery bypass grafting examined by means of transthoracic Doppler echocardiography

OBJECTIVE

We sought to investigate the changes of velocity profiles in the left anterior descending coronary artery after coronary artery bypass grafting using transthoracic Doppler echocardiography.

METHODS

Forty-five patients who received a bypass graft to the left anterior descending coronary artery were studied. Before coronary artery bypass grafting, Doppler velocity profiles of the distal left anterior descending coronary artery were recorded with transthoracic Doppler echocardiography. Peak systolic velocity, mean systolic velocity, peak diastolic velocity, mean diastolic velocity, total velocity time integral, systolic velocity time integral, and diastolic velocity time integral were measured. Three weeks after coronary artery bypass grafting, left anterior descending coronary artery antegrade flow in the distal portion of the anastomosis was obtained by using the same method. Coronary angiography was performed before and 3 weeks after coronary artery bypass grafting.

RESULTS

The overall success rate of measuring the left anterior descending coronary artery flow was 60.0% preoperatively and 80.0% postoperatively. In 25 patients, in whom all parameters were obtained both before and after coronary artery bypass grafting, the following increased significantly after coronary artery bypass grafting: peak systolic velocity (14.86 +/- 7.50 vs 25.07 +/- 17.02 cm/s, P =.0045), mean systolic velocity (9.86 +/- 5.42 vs 18.03 +/- 12.94 cm/s, P =.0026), peak diastolic velocity (24.26 +/- 12.54 vs 48.28 +/- 31.66 cm/s, P =.0021), mean diastolic velocity (14.94 +/- 6.65 vs 30.36 +/- 20.71 cm/s, P =.0022), diastolic velocity time integral (7.22 +/- 2.88 vs 15.55 +/- 10.39 cm, P =.0009), total velocity time integral (10.50 +/- 4.48 vs 19.27 +/- 12.63 cm, P =.0034), and diastolic-to-systolic velocity time integral ratio (3.09 +/- 1.53 vs 4.97 +/- 2.75, P =.0044). Angiography showed graft patency and no significant change in left anterior descending coronary artery stenosis in all patients.

CONCLUSIONS

Transthoracic Doppler echocardiography showed a significant increase in some parameters in left anterior descending coronary artery flow after coronary artery bypass grafting. Measurement of left anterior descending coronary artery flow by means of transthoracic Doppler echocardiography might be a noninvasive method to evaluate the effect of bypass grafting on the left anterior descending coronary artery.