Recent progress in coronary interventions--assessment by quantitative coronary angiography

Ultrasound bio-microscopy for measurement of coronary artery flow and estimation of infarct size in a mouse model of acute myocardial infarction

Ultrasound bio-microscopy was used to measure hemodynamic changes in the left main coronary artery after myocardial infarction (MI), and its usefulness in estimating infarct size was evaluated. MI was induced by left anterior descending artery ligation. Diastolic peak velocity (Vd), mean flow velocity (Vmean) and the velocity-time integral (VTI) were measured 2 and 6 h after MI. Serum troponin I levels were assayed 2, 6 and 12 h after MI. At 2 h, Vmean and VTI significantly differed between mice that underwent low and high left anterior descending artery ligation; Vd, Vmean and VTI were correlated with infarct size (r = -0.557, -0.693 and -0.672, respectively; all p < 0.01). Infarct size was more strongly correlated with 2-h ultrasound bio-microscopy measurements than with 2-h serum troponin I level. Measurement of coronary artery blood flow by ultrasound bio-microscopy may be useful for early estimation of infarct size in mice.

Impact of Angiotensin II Receptor Blockers on the Progression and Regression of Coronary Atherosclerosis An Intravascular Ultrasound Study

BACKGROUND

Although angiotensin II receptor blockers (ARB) have been found to reduce the coronary atherosclerotic plaque burden in animal models, it is unknown whether ARB have a similar effect on human coronary arteries.

METHODS AND RESULTS

Serial intravascular ultrasound (IVUS) studies of the left main (LM) coronary artery were performed in 64 patients at baseline and after 7-month follow-up. All patients were divided into 2 groups (ARB group: 23 patients; non-ARB group: 41 patients). Three-dimensional volumetric analysis was done throughout the LM coronary artery, and the volume index (VI; volume/length) was calculated for the vessel (VVI), lumen (LVI), and plaque (PVI). No significant difference was found between the 2 groups in baseline clinical characteristics, including age, gender, blood pressure levels, serum cholesterol levels, the presence of diabetes and smoking status. At baseline VVI, LVI and PVI were similar between the groups. In the non-ARB group, VVI, LVI, and PVI did not change between baseline and follow-up. In the ARB group, PVI significantly decreased during follow-up (9.9 +/-3.1 mm2 vs 9.1+/-2.7 mm2, p<0.01), whereas VVI and LVI were unaffected.

CONCLUSIONS

This preliminary IVUS study suggests that ARB could cause regression of coronary atherosclerosis in humans.

A case report of late coronary stent thrombosis manifested as acute myocardial infarction 19 months after stenting

A 63-year-old Japanese man was readmitted to our hospital due to acute broad-anterior myocardial infarction (AMI). The proximal left anterior descending artery (LAD) at the prior stent, which was implanted 19 months earlier and in which no angiographic restenosis was recognized 13 months before the second study, was totally occluded. After crossing a guide wire and balloon angioplasty, angiographic radiolucency was observed at the prior stent, suggesting that AMI was induced by late coronary stent thrombosis. Intravascular ultrasound performed 19 days after the onset of AMI revealed superficial calcification without significant stenosis and an atherosclerotic plaque distal to the stent that was not significantly changed compared to 19 months previously, consistent with the culprit lesion being an intrastent site. AMI may thus be induced by late coronary stent thrombosis during long-term clinical follow-up without clinical symptoms or angiographic restenosis at the second study.

Impact of the cross-sectional geometry of the post-deployment coronary stent on in-stent neointimal hyperplasia: an intravascular ultrasound study

To establish the relationship between the cross-sectional geometry of the post-deployment stent and the degree of in-stent neointimal hyperplasia (INH), intravascular ultrasound (IVUS) was used to examine cross-sections of the coronary arteries from 23 patients with coronary stents 6 months after implantation. Stent cross-sectional area (Sa) and stent perimeter (Sp) from 200 stent cross-sections, and the stent radius (Sr) and thickness of INH (Id) of 2,880 radial axes, were measured, and the mean degree of roundness (Rd) of stent cross-section was calculated for each stent as Rd=4piSa/Sp2. The degree of deformity (Df) of the stent cross-section was also calculated by comparing it with a hypothetical circle (the area of this hypothetical circle was equal to the Sa): Df=Sr/R, where R is the radius of the hypothetical circle. The area of INH was significantly larger in the Rd<0.87 group (n=84) than in the Rd> or =0.87 group (n=116) (3.83+/-1.26 vs 3.16+/-1.32 mm2, p<0.0005). There were significant differences in the thickness of INH among the 3 groups classified by the value of Df (Df<0.95: n=425, 0.21+/-0.12mm; 0.95< or =Df<1.05: n=2008, 0.29+/-0.15mm; Df> or =1.05: n=447, 0.34+/-0.15mm, overall p<0.0001). These data suggest that in-stent neointimal proliferation is more likely to occur in stented coronary arteries with a more oval than rounded cross-section, and particularly within the more pronounced and curved portion of the oval.

Relation of intraoperative flow measurement with postoperative quantitative angiographic assessment of coronary artery bypass grafting

BACKGROUND

It is critical to evaluate the anastomotic quality of coronary artery bypass grafting (CABG) in the operating room. The aim of this study is to determine the validity of intraoperative flow measurement for predicting the quality of CABG by comparison with the postoperative quantitative angiographic evaluation of the grafts.

METHODS

Eighty-two grafts, including 37 internal thoracic arteries, were examined intraoperatively with a transit-time flowmeter. Coronary angiograms were performed 14 +/- 5 days after CABG to quantify the diameters at the toe, heel, and anastomosis proper of the grafts.

RESULTS

There were significant differences between patent and nonpatent grafts in all intraoperative flow parameters. However, the only cut-off value to distinguish patent from nonpatent was a fast Fourier transformation (FFT) ratio of 1.0. FFT is the ratio of powers of the fundamental frequency and its first harmonic. Postoperative quantitative angiography indicated that the stenosis was greatest at the heel of the anastomosis. The degree of stenosis at the heel of the anastomosis alone correlated significantly with intraoperative mean flow values.

CONCLUSIONS

Fast Fourier transformation analysis of flow measurement may be useful to differentiate patent grafts intraoperatively. Intraoperative flow measurement may predict the most stenotic part of the anastomosis.

Beneficial application of quantitative coronary angiography (edge detection algorithm) in analysis of dissected coronary arteries to predict long-term patency

The present study evaluated the application of quantitative coronary angiography (edge detection algorithm) for the analysis of coronary dissection lesions after balloon angioplasty. Acute and late results were obtained by the edge detection algorithm in 60 patients with 66 dissected lesions (NHLBI types B-C). The edge detection algorithm delineated the border of the true lumen in 32 lesions (group with automated analysis alone, 48.5%) and included the dissection cap in the analysis in 34 lesions in which manual editing was adjuncted (group with manual editing, 51.5%). In both groups, the minimal lumen diameter after balloon angioplasty obtained by initial automated analysis was correlated to that obtained at the 5.3-month follow-up similarly (r=0.554, p=0.0010 for the group with automated analysis alone and r=0.613, p=0.0001 after automated analysis for the group with manual editing). However, additional manual editing reduced the correlation coefficient (r=0.240, p=0.1707) in the latter group. Thus, in terms of predicting long-term patency, it is reasonable to let the edge detection algorithm decide the measurements in types B and C dissected lesions.

Angioplasty-bypass surgery combination therapy: case study of an elderly patient with unstable angina and colon cancer

An 83-year-old man was admitted with refractory unstable angina and severe anemia. Colonofiberscopy revealed hemorrhagic colon cancer in the transverse colon. Coronary angiography showed total occlusion of the right coronary artery (RCA), diffuse, calcified 90% stenosis of the middle portion of the left anterior descending artery (LAD); and fair collaterals from the LAD to the RCA. Coronary revascularization was considered prior to colectomy, but because of the patient's advanced age and hemorrhagic cancer, conventional coronary aorta bypass grafting (CABG) using extracorporeal circulation, as well as coronary stenting requiring antiplatelet therapy, were regarded as inadvisable. Percutaneous transluminal coronary angioplasty (PTCA) for the LAD carried the risk of suboptimal coronary stenting. Thus, the patient was first treated with PTCA for the occluded RCA, followed 7 days later by a left internal thoracic artery graft to the LAD on the beating heart without extracorporeal circulation. The patient was stable thereafter. This approach to coronary revascularization may be suitable for patients for whom anticoagulation or antiplatelet therapy are contraindicated, or when complete revascularization would be difficult with CABG or PTCA alone.

A case of acute myocardial infarction due to primary coronary dissection

A case of acute myocardial infarction associated with primary coronary dissection was followed up angiographically. A 46-year-old woman complained of chest oppression. Electrocardiogram on admission showed ST-segment elevation in V1-5. Urgent coronary angiography was performed under a diagnosis of acute anterior myocardial infarction, and showed a significant stenosis with multiple filling defects in segments 7-8 (99% with severe delay) in the left anterior descending artery. There was no organic lesion in the right coronary artery. Intracoronary thrombolytic therapy was unsuccessful, and thereafter she was treated with aspirin, warfarin and isosorbide dinitrate. Coronary angiography performed 1 month later revealed a long dissection with double lumens in segments 7-8. The septal branches emerged from the smaller lumen. Two months later, the 2 lumens were almost equal in size. These findings indicated that coronary dissection produced a false lumen with an entry in segment 7 and a reentry in segment 8, and that the false lumen was responsible for the greater flow. Four months later, the flow in the true lumen had improved remarkably while that in the false lumen had almost disappeared. She remained in stable condition during the follow-up period of 4 months.