Two-dimensional echocardiographic analysis of proximal left main coronary artery in humans

Recent-onset of rheumatoid arthritis leads to increase in wall thickness of left anterior descending coronary artery. An evidence of subclinical coronary artery disease

OBJECTIVES

To explore the atherosclerotic changes of the left anterior descending coronary artery (LADCA) in patients with early onset of rheumatoid arthritis (RA).

METHODS

Transthoracic echocardiographic scans were performed on 15 early RA patients and 20 control subjects, free of rheumatological diseases, diabetes mellitus (DM), and cardiovascular disease (CVD). Out of 15 RA patients, 10 were matched for age and gender with control. Left anterior descending coronary artery wall thickness was compared between RA subjects and their matched control. Among early RA patients, correlation was assessed between LADCA wall thickness and the demographic features, RA activity features, and cardiovascular risk factors.  Results: Left anterior descending coronary artery wall thickness was significantly increased (p=0.001) in early RA compared to controls, as it was reported to be 0.61±0.04 mm (CI: 0.52-0.7); and 0.48±0.08 mm (CI: 0.44-0.51) respectively. Within early RA, LADCA wall thickness was related to the disease activity score (p=0.025, ß-coefficient 0.066, CI: 0.01-0.122) as well as to the patient global assessment of disease activity (PGADA) at RA onset (p=0.006, ß-coefficient 0.003, CI: 0.001-0.005), in a positive linear relationship. Left anterior descending coronary artery  wall thickness was found to be thicker among RA patients with rheumatoid factor (RF) positive (p=0.015, CI: 0.53-0.66). Conclusion: Early RA patients have increased coronary arteries atherosclerotic burden compared to healthy subjects matched for age, and gender. Rheumatoid factor positivity, high disease activity score and PGADA were found to be associated with coronary artery wall thickness.

Significance of the distal to proximal coronary flow velocity ratio by transthoracic Doppler echocardiography for diagnosis of proximal left coronary artery stenosis

OBJECTIVE

This study was designed to evaluate the significance of accelerated coronary flow velocity in the proximal left coronary artery by transthoracic Doppler echocardiography for detecting coronary stenosis.

METHODS

Seventy subjects with suspected coronary artery disease underwent successful coronary flow velocity measurement in both proximal and distal lesions by transthoracic Doppler echocardiography and coronary angiography.

RESULTS

On the basis of the coronary angiography results, 23 patients had significant (> or =50%) stenosis in the proximal left coronary artery (Group S) and 47 patients had no stenosis (Group N). The distal averaged diastolic peak velocity to proximal averaged diastolic peak velocity ratio (DAPAR) in Group S was significantly lower than that in Group N. A cutoff value of DAPAR < or = 0.5 for DAPAR predicted significant coronary stenosis with a sensitivity of 91% and a specificity of 72%.

CONCLUSION

Measurement of the DAPAR by transthoracic Doppler echocardiography is a promising method in the noninvasive diagnosis of stenosis in the proximal left coronary artery lesion.

Vasodilation of epicardial coronary artery can be measured with transthoracic echocardiography

Transthoracic Doppler echocardiography (TTE) has been introduced as a noninvasive tool to measure coronary flow velocity reserve (CFVR). Velocity measurement, however, fails to take into account epicardial coronary artery vasodilation during hyperemia and this may cause underestimation of CFVR measurements. Therefore, we sought to determine whether the vasodilation of epicardial coronary artery can be measured during cold pressor test (CPT) and adenosine infusion simultaneously with the flow velocity measurement using TTE. We studied 41 healthy nonsmoking men with a linear high-frequency 8.0-MHz transducer. The CPT and adenosine infusion dilated the diameter of the distal left anterior descending coronary artery (LAD) from 1.4 +/- 0.4 mm to 1.5 +/- 0.4 mm (14 +/- 13%, p < 0.01) and from 1.4 +/- 0.4 mm to 1.8 +/- 0.5 mm (31 +/- 19%, p < 0.01), respectively. The CPT increased flow velocity and calculated coronary blood flow rate (velocity time integral x cross-sectional area) from 0.23 +/- 0.05 m/s to 0.36 +/- 0.13 m/s (31 +/- 34%, p < 0.01) and from 8.1 +/- 4.2 mL/min to 11.4 +/- 6.0 mL/min (47 +/- 51%, p < 0.01). CFVR and calculated coronary blood flow rate reserve were 3.9 +/- 1.0 and 6.0 +/- 1.9, respectively. In Bland-Altman analysis, velocity measurements underestimated the vasodilation response of the CPT and adenosine compared with the measurements where epicardial diameter dilation was taken into account. Intra- and interobserver variability of diameter measurements was low (coefficient of variation [CV] 2.6 to 6.5%). Day-to-day, within-day and intersonographer variabilities were of similar magnitude (CV 4.6 to 8.2%), suggesting good reproducibility. This study demonstrates that TTE can be used to assess changes in both epicardial coronary artery diameter and flow velocity simultaneously in the distal LAD artery.

Comparison of high-frequency two-dimensional transthoracic echocardiography versus intravascular ultrasound for evaluation of the left anterior descending coronary artery

The purpose of this study was to evaluate the feasibility of high-frequency transthoracic echocardiography for measuring the wall thickness and luminal area of the left anterior descending coronary artery (LAD). Fifteen patients underwent simultaneous high-frequency transthoracic echocardiography and intravascular ultrasound (IVUS) examinations. There were good agreements for wall thickness (0.38 +/- 0.05 vs 0.38 +/- 0.06 mm, p = 0.0004) and luminal area (3.24 +/- 1.05 vs 3.32 +/- 1.34 mm2, p <0.0001) between high-frequency transthoracic echocardiography and IVUS measurements. High-frequency transthoracic echocardiography was reliable in the measurement of the wall thickness and luminal area of the LAD.

Pattern of exercise-induced ST change is related to coronary flow reserve in patients with chest pain and normal coronary angiogram

OBJECTIVE

To evaluate the usefulness of exercise treadmill test in determining the true microvasculature-induced ischemia, we compared the pattern of ST depression with coronary flow reserve (CFR) using transthoracic Doppler echocardiography (TTE) in patients with chest pain and normal coronary angiogram.

DESIGN

Fifty-nine subjects (M/F=21:38, mean age 55+/-9 years) with chest pain and normal coronary angiogram underwent maximal symptom-limited exercise treadmill test (ETT). CFR was estimated with TTE and dipyridamole. Patients with a history of acute myocardial infarction, regional wall motion abnormalities, hypertrophic cardiomyopathy, ejection fraction less than 50%, or primary valvular heart disease were excluded from this study.

RESULTS

No ST change was observed in 20 of 59 (34%) patients, up slope depression was observed in 20 (34%), flat depression in 13 (22%), and down slope depression in 6 (10%). Eleven of thirty nine (28%) exercise positive patients had decreased CFR <2.1. CFR was 3.1+/-0.6 in group with no ST change, 3.1+/-0.6 in group with up slope depression, 2.1+/-0.6 in group with flat depression (p<0.05 versus group with no change and group with upslope depression, respectively), and 2.0+/-0.4 in group with down slope depression (p<0.05 versus group with no change and group with up slope depression, respectively). Flat to down slope depression of ST change during ETT had sensitivity of 58% and specificity of 95% for predicting CFR <2.1.

CONCLUSION

Flat and down slope depression of ST segment during ETT might increase the sensitivity and specificity to detect the true microvasculature-induced ischemia that is defined as CFR less than 2.1 in patients with chest pain and normal coronary angiogram.

Potential use of high-resolution two-dimensional transthoracic echocardiography for visualization of the left anterior descending coronary artery

High-resolution, two-dimensional transthoracic echocardiography (HR-2DTTE) can detect the difference in the left anterior descending coronary artery (LAD) wall thickness between patients with coronary artery disease and patients with normal coronary arteries. However, HR-2DTTE measurements of the LAD wall thickness are larger than measurements obtained by intravascular ultrasound and histology. This difference may be due to the inclusion of adventitia by HR-2DTTE. We evaluated the contribution of adventitia to the wall thickness of the normal and atherosclerotic LAD by comparing HR-2DTTE with high-frequency epicardial echocardiography. The LAD wall thickness was significantly greater in patients with coronary artery disease by both HR-2DTTE and high-frequency epicardial echocardiography. Both an increase in the intima plus media thickness and an increase in the thickness of adventitia contributed to the increase in the LAD wall thickness in patients with coronary artery disease. Adventitia represents a significant portion of the LAD wall thickness imaged by HR-2DTTE and its thickness increases significantly with the development of atherosclerosis.

Coronary artery diameter can be assessed reliably with transthoracic echocardiography

We studied whether diameters of coronary arteries can be measured accurately with the use of transthoracic echocardiography (TTE). By knowing the anatomic diameter of the coronary artery together with coronary flow velocity it is possible to measure coronary flow volume more precisely by TTE. However, the suitability of TTE for measurement of diameters of all main epicardial coronary arteries has not been systematically validated. We measured the diameters of the left main (LM), left anterior descending (LAD), left circumflex (LCX), and right coronary arteries (RCA) with the use of TTE [manual two-dimensional (2D), color-Doppler, and automated 2D analysis] in 30 patients who had normal coronary anatomy. We compared these diameters to those measured with quantitative coronary angiography (QCA). We could measure diameters of LM, LAD, LCX, and RCA by TTE in up to 37%, 63%, 7%, and 60% of patients, respectively. The overall correlation coefficients between TTE and QCA measurements were 0.83 ( P < 0.01) with manual 2D analysis, 0.82 ( P < 0.01) with automated 2D analysis, and 0.94 ( P < 0.01) with a color-Doppler-based analysis. Interobserver variability of TTE measurements was low (coefficient of variation 5.4 ± 4.6–7.5 ± 8.8%). TTE is an accurate method to evaluate coronary artery diameter in patients with healthy coronary arteries.

Detection of subclinical coronary atherosclerosis using two-dimensional, high-resolution transthoracic echocardiography

OBJECTIVES

We evaluated whether two-dimensional high-resolution transthoracic echocardiography (HR-2DTTE) can detect changes in arterial wall thickness and size associated with subclinical coronary artery disease (CAD).

BACKGROUND

Arterial wall thickening, compensatory arterial enlargement and a preserved arterial lumen characterize subclinical atherosclerosis. Detection of these changes during the asymptomatic stage of CAD may allow early treatment and prevention of acute coronary events.

METHODS

Twenty-six patients with angiographically proven CAD and 29 normal volunteers underwent HR-2DTTE evaluation of the left anterior descending coronary artery (LAD) using an ATL 5000 echograph (Advanced Technology Laboratories, Bothell, Washington) with a 4 to 7 MHz transducer. Significant (>70%) LAD stenosis was present in 15 patients (mean 82%); 11 patients did not have significant LAD stenosis (mean 26%) and represented a surrogate for subclinical LAD disease. Wall thickness, maximal luminal diameter and external diameter of the LAD were measured.

RESULTS

Left anterior descending coronary artery wall thickness was larger in patients (1.9 +/- 0.4 mm) than it was in volunteers (0.9 +/- 0.1 mm, p < 0.001). The external diameter of the LAD was (6.0 +/- 1.1 mm) in patients and (3.9 +/- 0.7 mm) in volunteers (p < 0.001). Luminal diameter was 2.2 +/- 0.5 mm in patients and 2.1 +/- 0.6 mm in volunteers (p = NS). There was no difference in wall thickness (1.9 +/- 0.4 mm vs. 2.0 +/- 0.4 mm), luminal diameter (2.2 +/- 0.5 mm vs. 2.2 +/- 0.4 mm) and external diameter (5.9 +/- 1.0 mm vs. 6.2 +/- 1.2 mm) between the patients with <70% and >70% LAD stenosis.

CONCLUSIONS

Left anterior descending coronary artery wall thickness and external diameter are significantly increased in patients with CAD as compared with normal subjects, and HR-2DTTE is sensitive enough to detect these differences. Wall thickness and external diameter are increased to the same extent in patients with obstructive and subclinical LAD disease.

Value of acceleration flow and the prestenotic to stenotic coronary flow velocity ratio by transthoracic color Doppler echocardiography in noninvasive diagnosis of restenosis after percutaneous transluminal coronary angioplasty

OBJECTIVES

The study evaluated the value of coronary flow velocity measurement by transthoracic color Doppler echocardiography (TTCDE) for the noninvasive diagnosis of restenosis after percutaneous transluminal coronary angioplasty (PTCA) for left anterior descending coronary artery (LAD) lesions.

BACKGROUND

Recent advances in TTCDE provide coronary flow velocity measurements in the LAD under the guidance of color flow mapping.

METHODS

We studied 53 patients who underwent successful PTCA for LAD lesions and follow-up coronary angiography (18 patients with restenosis [Group-R], 35 patients without restenosis [Group-N]). We searched localized color aliasing corresponding to local flow acceleration to obtain coronary flow velocity at PTCA sites in the LAD. When localized aliasing was detected, we measured coronary flow velocity at the aliasing (stenotic site) and the prestenotic site.

RESULTS

Using TTCDE, it was possible to measure mean diastolic velocity (MDV) in the LAD in 41 (77%) of 53 patients (14 of 18 patients in Group-R; 27 of 35 patients in Group-N). Localized aliasing was displayed by color flow mapping in 14 (100%) of 14 patients in Group-R, and 15 (56%) of 27 patients in Group-N. Stenotic MDV in Group-R was significantly higher than that in Group-N (60.3 +/- 21.1 vs. 35.1 +/- 7.6 cm/s, p < 0.01), although prestenotic MDV did not differ between Group-R and Group-N (20.2 +/- 3.0 vs. 19.6 +/- 2.3 cm/s). There were significant differences in the prestenotic to stenotic MDV ratio between Group-R and Group-N (0.36 +/- 0.10 vs. 0.57 +/- 0.09, p < 0.001). Localized aliasing with the prestenotic to stenotic MDV ratio <0.45 as the optimal cutoff value had a sensitivity of 86% and a specificity of 93% for the presence of restenosis in LAD lesions.

CONCLUSIONS

Detection of localized color aliasing and measurement of the prestenotic to stenotic MDV ratio in the LAD by TTCDE are useful in the noninvasive diagnosis of restenosis after PTCA for LAD lesions.

Coronary artery aneurysms: A 25-patient study

Coronary artery aneurysm is a rare disorder, characterized by abnormal dilatation of a localized portion or diffuse segments of the coronary artery. We studied clinical demographics, catheterization findings, and clinical outcomes in an Asian patient cohort with documented coronary artery aneurysms. Compared to a Caucasian adult population, our patient cohort had a lower incidence of coronary artery aneurysm (0.25% vs. 2.6%), and more patients with nonobstructive coronary artery aneurysms (70%); age, gender, and coronary distribution were comparable. The initial presentation of myocardial infarction occurred in five patients (5/17, 30%) with nonobstructive coronary artery aneurysms; however, none who were receiving preventive medications consisting of anticoagulant and antiplatelet agents subsequently developed myocardial infarction. We conclude that the incidence of coronary artery aneurysms with or without associated significant coronary stenosis seems to be lower in the Asian population. In contrast, the incidence of nonobstructive coronary artery aneurysms is considerably high and should not be thought of as a relatively benign disease entity if not treated with preventive medications. Rheumatoid arthritis-related vasculitis might be a cause of coronary artery aneurysm. Surgical intervention is based on the severity of coronary artery stenosis. The result of medical treatment has been compatible with long-term survival. Cathet. Cardiovasc. Intervent. 48:31-38, 1999.

Coronary artery aneurysm: a review

Coronary artery aneurysm is defined as coronary dilatation which exceeds the diameter of normal adjacent segments or the diameter of the patient's largest coronary vessel by 1.5 times. This is an uncommon disease which has been diagnosed with increasing frequency since the advent of coronary angiography. The incidence varies from 1.5% to 5% with male dominance and a predilection for the right coronary artery. Atherosclerosis accounts for 50% of coronary aneurysms in adults. Reported complications include thrombosis and distal embolization, rupture and vasospasm. The natural history and prognosis remains obscure. Controversies persist regarding the use of surgical or medical management. The authors recommend surgery based on the severity of associated coronary stenosis rather than the mere presence of aneurysm. Medical therapy is indicated for the majority of patients and consists of antiplatelet and anticoagulant medication.

Transthoracic echocardiographic detection of coronary atherosclerosis

Coronary atherosclerosis is a pathologic process that produces thickening of the walls of the coronary arteries to the point that flow through those vessels may be impaired. This study attempts to use transthoracic echocardiography to detect coronary atherosclerosis. Eighty-nine patients undergoing coronary angiography were examined with a broad-band ultrasonic transducer with a frequency between 3 and 5 MHz. A modified short axis examination was utilized to identify left main and proximal left anterior descending arteries. The examination was recorded digitally and displayed in a 32-cell, quad screen cine loop. Fifty-six of the 89 patients (63%) had obstructive coronary artery disease (CAD) (i.e, at least 1 vessel with 50% obstruction). There were 14 patients with CAD but no vessel had > or = 50% obstruction. Nineteen patients (21%) had angiographically normal arteries. The coronary echograms were judged qualitatively for brightness, uniformity, and persistence (defined as the ability to see segments of the artery walls in more frames than other segments). The length of the coronary artery visualized, the width of the left main coronary artery, and the width of the thickest segment of the coronary artery walls were quantitatively measured. More than 2 cm of the left coronary artery was seen in almost all patients. Segmental changes were noted in 52 of the 56 patients with obstructive CAD, 12 of the 14 patients with nonobstructive CAD, and 3 of the 19 patients with normal arteries. Persistence greatly enhanced the ability to judge the segmental changes. Forty-six patients with obstructive disease had wall thickness > or = 1.5 mm. Only 6 patients with nonobstructive coronary arteries had this wall thickness, and only 1 normal subject had thick walls. The ultrasonic findings were useful in predicting the presence or absence of coronary atherosclerosis to varying degrees of sensitivity and specificity based on the segmental findings and wall thickness measurements. The results of this study indicate that a transthoracic ultrasonic examination of the proximal left coronary artery could be a clinically valuable tool in the qualitative identification of coronary atherosclerosis.

Echocardiographic visualization of anomalous left main coronary arteries originating from the right sinus of Valsalva

We report on two patients in whom the anomalous left main coronary artery arising from the right sinus of Valsalva with a septal course could be visualized by transthoracic echocardiography. It appeared as a small echo-free space, anterior to the aorta in the short parasternal axis. If the left main coronary artery arises anomalously from the right sinus of Valsalva, it can take four different courses until it branches into the left anterior descending and the circumflex coronary artery. The course between aorta and pulmonary trunk can be differentiated into an interarterial and a septal course using angiographic criteria. The interarterial course is a potentially life-threatening anomaly due to a high rate of myocardial infarction and sudden cardiac death. Echocardiography alone seems not to be able to distinguish between the potentially life-threatening interarterial and the benign septal course, as in our patients.

Anatomy, histology, and pathology of coronary arteries: a review relevant to new interventional and imaging techniques--Part IV

In the last 15 years, intense interest has focused on various interventional pharmacologic and mechanical forms of therapy for the treatment of atherosclerosis coronary artery disease. Many techniques and devices (dilating balloons, perfusion catheters, thermal probes and balloons, lasers, atherectomy devices, stents, intravascular ultrasound) have been used or are under study for future use. Many of these techniques and devices require an understanding of histologic and pathologic features of the coronary arteries and diseases which affect them. This article reviews selective areas of anatomy, histology, and pathology relevant to the use of various new interventional techniques. Part IV of this review will focus on congenital coronary artery anomalies, myocardial bridges, coronary aneurysm, emboli, and dissection and clinical implications regarding echocardiographic imaging techniques.

Coronary artery aneurysms--a case study and literature review

Coronary artery aneurysms are detected with increasing frequency owing to the advent of coronary angiographies. Although most patients with coronary artery aneurysms are asymptomatic, manifestations of myocardial ischemia may occur. The case described herein serves as a basis for a discussion of the pathogenesis, clinical manifestations, detection, and treatment of coronary artery aneurysms.

Anomalous origin and course of coronary arteries in adults: identification and improved imaging utilizing transesophageal echocardiography

Anomalous origin of a coronary artery is rare, but may represent a clinically significant abnormality, since some anomalies are associated with myocardial ischemia, infarction, and sudden death. Diagnosis may elude routine screening procedures, and even when an anomalous vessel is identified angiographically, it may be difficult to delineate its true course on the basis of angiography alone. The purpose of this study was to determine whether transesophageal echocardiography (TEE) is of value in making the diagnosis and outlining the course of anomalous coronary arteries. Five adult patients with anomalous origin of a coronary artery were studied by monoplane TEE and selective coronary angiography. Transthoracic echocardiography (TTE) was also performed in four of these five patients. Anomalous coronary ostia were visualized in four of five patients utilizing TEE, but in none of four patients by TTE. A proximal segment of the anomalous coronary vessel was identified in all five patients by TEE, and in only two of four patients by TTE. TEE images were consistently of superior diagnostic quality. TEE is a valuable tool for the echocardiographic identification of anomalous coronary arteries, and is superior to TTE in adult patients.

Transthoracic ultrasonic visualization of coronary atherosclerosis

Although transthoracic ultrasonic visualization of the coronary arteries is technically demanding, many groups of investigators have demonstrated the feasibility of recording the proximal coronary arteries. Technical advances such as the introduction of anular array transducers and digital recording techniques have improved the prospect of obtaining this examination in a reasonable number of patients. It is now possible to detect atherosclerotic disease in the left main and the proximal left anterior descending coronary artery in 70% to 80% of all patients. This echocardiographic technique appears to be a sensitive means of detecting coronary atherosclerosis. Preliminary data suggest that this examination may be helpful in making the differential diagnosis of ischemic cardiomyopathy and idiopathic dilated cardiomyopathy.

Imaging of the coronary arteries by transesophageal echocardiography

Detection of the proximal left and right coronary arteries is possible by transesophageal echocardiography with rather high frequencies. The proximal left coronary artery can be detected in 86% of patients and the proximal right in 82%. Precise identification of obstructive disease is possible but is confounded by heart movement and as yet inadequate criteria for its presence to make this routinely clinically possible. It is also possible to detect flow within these vessels with conventional pulsed or Doppler color flow methods. Given recent improvements in system performance, it is likely that adequate descriptors of proximal coronary anatomy and obstruction will be likely with these approaches.

Anatomy, histology, and pathology of the major epicardial coronary arteries relevant to echocardiographic imaging techniques

We are at the threshold of a new era of coronary artery imaging with the use of transthoracic, transesophageal, and intravascular ultrasound. Echocardiographic imaging has the capability of assessing changes of the lumen and walls of major epicardial coronary arteries. This article reviews certain anatomic, histologic, and pathologic observations of the major epicardial coronary arteries relevant to these various echocardiographic imaging techniques.

Transesophageal echocardiography

Two-dimensional transesophageal echocardiography generally has superior sensitivity and image quality compared with precordial echocardiography. Its unique anatomic perspective posterior to the heart often provides important clinical information not obtainable by other imaging approaches and technologies. It is particularly useful in the diagnosis of mitral valve disease, left atrial masses, endocarditis and its sequelae, and aortic dissections. It is also useful for examination of the left main coronary artery, left ventricular outflow tract, atrial and ventricular septa, and congenital defects. In addition to its application as a diagnostic tool in conscious patients, it can be employed intraoperatively to evaluate and guide surgical intervention. Detection of ventricular wall motion abnormalities by transesophageal echocardiography has been shown to be the most sensitive indicator of myocardial ischemia available in the clinical setting. It has potential for wide application for safely monitoring left ventricular function in patients in intensive care or under anesthesia.