Determination of coronary flow measurements by transesophageal echocardiography: dependence of flow velocity reserve on the location of stenosis

Coronary Artery Assessment by Epicardial Pulsed Doppler Ultrasound

An intraoperative method was developed for direct investigation of the coronary arteries using an epicardial high-frequency two-dimensional Doppler ultrasound transducer. This fingertip 7.5-MHz transducer was used in 30 patients undergoing coronary artery bypass surgery to measure blood flow in the coronary arteries and bypass grafts. In all the patients, clear images of the coronary arteries and the bypass grafts were obtained in the beating heart, and coronary blood flow could be measured to evaluate the degree of stenosis. There were no significant differences between the measurements obtained with the Doppler transducer and a transit-time ultrasonic flowmeter of blood flow in the left internal thoracic artery graft to the left anterior descending coronary artery, indicating that the Doppler method produces accurate and reproducible measurements. This method can provide useful intraoperative information about the coronary artery system in emergency operations such as acute aortic dissection.

[Evaluation of vascular function by modern non-invasive methods]

Vascular functional alterations frequently precede morphological changes and, therefore, their recognition may theoretically improve early detection of vascular injury. The aim of this review is to demonstrate recently available non-invasive clinical methods including vascular stiffness examinations, flow-mediated vasodilatation, coronary flow reserve and myocardial flow reserve measurements.

Long-term prognostic value of coronary flow reserve in patients without significant left anterior descending coronary artery stenosis: results from the SZEGED Study

A coronariaáramlási rezerv (CFR) a bal coronaria leszálló szárában (LAD) szignifikáns szűkület hiánya esetén a microvascularis (disz)funkció jellemzésére használható hemodinamikai index. Célkitűzés: Jelen tanulmány célja a LAD-ban mért CFR prognosztikus értékének tisztázása lenne, amennyiben a koronarográfia során a LAD-ban szignifikáns szűkület nem volt igazolható. Módszerek: A jelen tanulmányban 166 olyan beteg eredményeit elemeztük, akiknél a CFR-vizsgálatok idején elvégzett koronarográfia a LAD-ban szignifikáns szűkületet (>50%) nem mutatott ki. Valamennyi esetben transthoracalis és terheléses transoesophagealis echokardiográfia (CFR-mérés), valamint koronarográfia történt. Eredmények: A továbbkövetés átlagos ideje 93±34 hónap volt, sikeressége 75%-osnak bizonyult (124/166). A továbbkövetés időszaka alatt 27 beteg hunyt el, 16 beteg esetén hirtelen szívhalál, 3 esetben akut szívelégtelenség, 2 esetben stroke volt a halál oka, míg 6 beteg pulmonalis, illetve gastrointestinalis tumoros folyamat miatt halt meg. A ROC-analízis során a CFR ≥ 2,13-t találtuk a legnagyobb pontosságú cut-off (határ-) értéknek a túlélés előrejelzésében (szenzitivitás 67%, specificitás 60%, görbe alatti terület 62%, p = 0,046). A 2,13-nál alacsonyabb CFR-rel bíró betegekben a továbbkövetés során szignifikánsan több esemény történt, mint az annál nagyobb értékkel bíróknál (32% vs. 13%, p < 0,05). A multivariáns logisztikus regressziós modell során a CFR [hazard ratio (HR) 2,43, p = 0,04] és a bal kamrai végszisztolés térfogatérték [HR 1,49, p = 0,03] bizonyult a túlélés független prediktorának. Következtetések: Hosszú távú továbbkövetéses vizsgálataink alapján megállapíthatjuk, hogy a CFR a túlélés független prediktora a LAD szignifikáns szűkületét nem mutató betegekben.

The coronary flow velocity reserve measured by stress transoesophageal echocardiography evaluates the success of coronary interventions – Results of a 5-year follow-up

OBJECTIVES

The aim of the present study was to examine the long-term prognostic value of coronary flow velocity reserve (CFR) evaluated by means of stress transoesophageal echocardiography (STEE) in patients who have undergone percutaneous coronary intervention (PCI).

DESIGN

The study comprised 31 patients with significant LAD stenosis who underwent LAD-PCI. In consequence of their clinical signs, 11 subjects required rePCI or coronary artery bypass graft (CABG) operation within six months. The clinical status of the remaining 20 cases improved during the follow-up. STEE examinations were performed before LAD-PCI and after it.

RESULTS

The CFR of patients in a stable clinical condition improved during the follow-up, while the CFR of those who required rePCI or CABG remained unchanged. From this patient population, two subjects died during the 5-year follow-up.

CONCLUSIONS

Most of the patients who displayed an improved CFR after PCI suffered no major clinical events during the 5-year follow-up; in contrast, in those who a priori had a low CFR and did not show any improvement after PCI, major events did occur during this period.

Grade of aortic atherosclerosis: a valuable adjunct to coronary flow velocity reserve in the evaluation of coronary artery disease

BACKGROUND

Atherosclerosis is a generalized disease of the arterial vasculature; among thus it manifests in the descending aorta and the coronary arteries. We tested whether known risk factors, the coronary flow velocity reserve and the grade of aortic atherosclerosis detected by transoesophageal echocardiography in the course of the same semi-invasive examination is able to distinguish between patients with significant left anterior descending coronary artery (LAD) stenosis or with multivessel disease.

METHODS AND RESULTS

The present study involved 125 consecutive patients (mean age: 56 +/- 11 years, range: 22-73) with chest pain undergoing coronary angiography. Grade of aortic atherosclerosis was obtained by means of transoesophageal echocardiography, and the coronary flow velocity reserve was calculated in the left anterior descending coronary artery. The age (ROC area, 63%, p<0.01), the gender (ROC area, 63%, p<0.02) and the grade of aortic atherosclerosis (ROC area, 64%, p<0.01) exhibited good power for the prediction of patients with multivessel disease from among all other patients. Only the grade of aortic atherosclerosis (ROC area, 63%, p<0.05) appears useful to distinguish patients with left anterior descending coronary artery disease from those with multivessel disease.

CONCLUSIONS

These results demonstrate that grade of aortic atherosclerosis furnishes additional help in the prediction of patients with severe coronary artery disease. It can differentiate patients with multivessel disease from those with significant left anterior descending coronary artery stenosis. Coronary flow velocity reserve has no any prognostic power in this evaluation.

Non-invasive measurement of coronary flow reserve in children with Kawasaki disease

OBJECTIVE

To investigate whether transthoracic Doppler echocardiography (TTE) can reliably measure the coronary flow reserve in the left anterior descending coronary artery in children with Kawasaki disease.

DESIGN

Coronary flow velocity in the distal left anterior descending coronary artery was measured by TTE and was compared with that obtained by intracoronary Doppler guide wire. The ratio of maximum hyperaemia (intravenous administration of adenosine triphosphate, 160 microg/kg/min) to baseline peak (mean) diastolic coronary flow velocity in the distal artery was used as an estimate of coronary flow reserve.

SETTING

University hospital.

PATIENTS

10 patients with significant left anterior descending coronary stenosis (> 70% diameter stenosis) (group A) in the proximal or middle portion of the artery and 14 patients (group B) without significant stenosis, all with Kawasaki disease documented by previous coronary angiography.

RESULTS

The reduced hyperaemic coronary flow velocity in group A compared with group B resulted in a markedly lower coronary flow reserve, derived from both peak diastolic velocity and mean diastolic velocity by either technique of investigation. Multivariate analysis identified the best predictor of left anterior descending coronary artery stenosis to be a coronary flow reserve of < or = 2.2, derived from mean diastolic flow velocity measured using TTE (sensitivity 90%, specificity 100%, accuracy 96%). A good correlation was found between diastolic velocity derived values for coronary flow reserve measured using both TTE and Doppler guide wire (r = 0.92, p = 0.0001).

CONCLUSIONS

Coronary flow reserve in the distal left anterior descending coronary artery can be accurately measured using TTE without any intravascular instrumentation in children with Kawasaki disease.

Serial evaluation of coronary flow reserve by transesophageal doppler echocardiography after angioplasty of proximal left anterior descending coronary artery: a 6-month follow-up study

BACKGROUND

Coronary flow reserve can be estimated by transesophageal Doppler echocardiography (TDE).

OBJECTIVE

To evaluate the coronary flow reserve by TDE, serially over 6 months' follow-up, after successful percutaneous transluminal coronary angioplasty (PTCA) of proximal left anterior descending coronary artery (LADA).

METHODS AND RESULTS

We performed TDE examination of 30 patients (mean age 55 +/- 9 years) 72 h, 3 months, and 6 months after PTCA of LADA. Selective angiography of LADA was repeated 72 h and 6 months after PTCA of LADA. Velocity of flow in LADA was measured before and 2 min after cessation of intravenous infusion of dipyridamole (0.56 mg/kg in 4 min). The dipyridamole: rest mean diastolic velocity ratio was considered as an index of coronary flow reserve (CFR). For 20 of 21 patients with CFR > 2 there was no restenosis, whereas coronary angiography revealed restenosis in eight of nine patients with CFR < 2. The sensitivity was 88.9% and the specificity was 95.2%. For the 21 patients without restenosis mean CFR was 2.1 +/- 0.1 72 h after PTCA, had increased to 3.1 +/- 0.3 (P < 0.0001) 3 months after PTCA, and remained stable thereafter (3.0 +/- 0.9).

CONCLUSION

CFR after PTCA of proximal LADA can be evaluated serially by transesophageal Doppler echocardiography. CFR of LADA in patients without restenosis is increased 3 months after PTCA and remains stable thereafter.

Transesophageal Echocardiographic Assessment of Proximal Coronary Artery Stenosis in Elderly Patients With Ischemic Stroke

Coronary artery disease is common in elderly patients with ischemic stroke. Most patients with ischemic stroke undergo transesophageal echocardiography to rule out cardiac sources of cerebral embolism. Transesophageal echocardiography has been shown to be very accurate in diagnosing significant proximal coronary artery stenosis, and may be used to evaluate the coronary arteries for the presence of stenosis in elderly patients with ischemic stroke. Transesophageal echocardiographic detection of these lesions might lead to subsequent coronary angiography and revascularization, dramatically changing the management and outcome of these patients. (c) 2000 by CVRR, Inc.

Definition of flow parameters in proximal nonstenotic coronary arteries using transesophageal Doppler echocardiography

Transesophageal echocardiography (TEE) enables the visualization of proximal coronary arteries. We investigated the feasibility of coronary flow evaluation using TEE, as well as to define flow parameters found in normal proximal coronary arteries. The subgroups of patients with normal proximal segments of coronary arteries were selected from the cohort of 210 patients undergoing routine coronary angiography. The left main coronary artery (LMCA), proximal segment of left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were analyzed separately in 147, 64, 53, and 70 patients, respectively. Proximal coronary arteries were evaluated in the transverse plane using a 5-MHz TEE probe, and the flow in normal arteries was registered using pulsed-wave Doppler. The registration of flow with pulsed-wave Doppler was feasible in 88% of studies for the LMCA, 85% for the LAD, 58% for the LCx, and 65% for the RCA. Normal flow was laminar with distinct phasic character (diastolic predominance). Mean +/- SD values of peak coronary flow velocity were (systole/diastole) for the LMCA, 36 +/- 11/71 +/- 19 cm/sec; the LAD, 31 +/- 9/67 +/- 19 cm/sec; the LCx, 36 +/- 13/75 +/- 24 cm/sec; and the RCA, 25 +/- 8/39 +/- 12 cm/sec. Peak diastolic coronary flow velocity was most significantly correlated with heart rate. Doppler evaluation of proximal coronary flow is feasible using TEE in the majority of patients. The knowledge of normal flow values, which is different for the left and the right coronary artery, provides the background for proper interpretation of flow in diseased coronary arteries.

Usefulness of the response of flow velocity in the left anterior descending coronary artery to the cold pressor test for evaluating endothelium-dependent vascular relaxation in the coronary microvasculature by transesophageal echocardiography in subjects with angiographically normal coronary arteries

Measurement of flow velocity in the left anterior descending coronary artery by transesophageal echocardiography in subjects without risk factors for coronary artery disease (group 1) and in subjects with normal coronary arteries but conditions associated with endothelial dysfunction (group 2) revealed that there was a significantly impaired coronary flow velocity response to the cold pressor test in group 2 subjects. Thus, transesophageal echocardiography provides a minimally invasive tool for the functional assessment of endothelium and can be valuable in evaluating endothelial dysfunction and recovery in a variety of disease states.

Visualization and functional assessment of proximal and middle left anterior descending coronary stenoses in humans with magnetic resonance imaging

BACKGROUND

Coronary artery bypass grafting improves survival in patients with >70% luminal diameter narrowing of the 3 major epicardial coronary arteries, particularly if there is involvement of the proximal portion of the left anterior descending (LAD) coronary artery. Measurement of coronary flow reserve can be used to identify functionally important luminal narrowing of the LAD artery. Although magnetic resonance imaging (MRI) has been used to visualize coronary arteries and to measure flow reserve noninvasively, the utility of MRI for detecting significant LAD stenoses is unknown.

METHODS AND RESULTS

Thirty subjects (23 men, 7 women, age 36 to 77 years) underwent MRI visualization of the left main and LAD coronary arteries as well as measurement of flow in the proximal, middle, or distal LAD both at rest and after intravenous adenosine (140 microgram/kg per minute). Immediately thereafter, contrast coronary angiography and when feasible, intracoronary Doppler assessments of coronary flow reserve, were performed. There was a statistically significant correlation between MRI assessments of coronary flow reserve and (a) assessments of coronary arterial stenosis severity by quantitative coronary angiography and (b) invasive measurements of coronary flow reserve (P<0.0001 for both). In comparison to computer-assisted quantitative coronary angiography, the sensitivity and specificity of MRI for identifying a stenosis >70% in the distal left main or proximal/middle LAD arteries was 100% and 83%, respectively.

CONCLUSIONS

Noninvasive MRI measures of coronary flow reserve correlated well with similar measures obtained with the use of intracoronary Doppler flow wires and predicted significant coronary stenoses (>70%) with a high degree of sensitivity and specificity. MRI-based measurement of coronary flow reserve may prove useful for identification of patients likely to obtain a survival benefit from coronary artery bypass grafting.

Measurement of coronary flow reserve in children by transthoracic Doppler echocardiography

Noninvasive measurement of coronary flow reserve was performed by transthoracic color Doppler echocardiography in 28 children with Kawasaki disease.