J Thorac Cardiovasc Surg 1994;107:323-325
© 1994 Mosby, Inc.
Extent and distribution of the perfusion areas of the coronary artery selected for bypass grafting: Assessment by intraoperative myocardial contrast echocardiography
Nobuaki Hirata, MD,
Susumu Nakano, MD,
Kei Sakai, MD,
Shigehiko Sakaki, MD,
Hikaru Matsuda, MD
First Department of Surgery
Osaka University Medical School
1-1-50. Fukushima, Fukushima-ku
Osaka 553, Japan
To the Editor:
Preliminary experience with intraoperative use of myocardial contrast echocardiography demonstrated that this method had allowed direct real-time evaluation of the magnitude and geometry of regional myocardial perfusion of the native coronary artery selected for bypass grafting
1,2. We thus performed myocardial contrast echocardiography to evaluate the effectiveness of myocardial revascularization during operations. 3,4 The following case study demonstrated that intraoperative myocardial contrast echocardiography could be useful for intraoperative evaluation of the effectiveness of the surgical procedure and concomitant intraoperative decision making.
A 55-year-old man with a history of an inferior wall myocardial infarction was admitted with increasingly severe retrosternal chest pain. Coronary arteriography revealed significant two-vessel disease, including a 100% stenosis of the proximal left anterior descending coronary artery (LAD) with good collaterals from the conus branch of the right coronary artery (RCA) and a 99% stenosis of the mid-RCA (Fig. 1). The patient underwent bypass grafting for these vessels with saphenous vein grafts 1 week after coronary arteriography. A 1.5 mm probe passed distally in the LAD. After termination of cardiopulmonary bypass, myocardial contrast echocardiography was performed by a bolus injection of sonicated 5% human albumin into each saphenous vein graft. Transesophageal echocardiography (model 65A ultrasound system, Toshiba Corporation, Tokyo, Japan) was used with a 5.0 MHz transducer by imaging a cross-sectional view obtained at the papillary muscle level of the left ventricle. The perfusion area of the RCA included the inferoseptal and inferior walls. The perfusion area of the LAD was limited to the anteroseptal region, and its extent, which was expressed by means of the ratio of the circumference between enhanced borders to a full circle, was only 7.2% (Fig. 2), although we had estimated from the preoperative coronary arteriogram that the LAD would perfuse the anteroseptal and anterior regions (Fig. 3). 4 Accordingly, we decided that it was necessary to secure additional blood flow to the distal LAD with a saphenous vein graft. The proximal site was anastomosed to the former saphenous vein graft (Y-shaped graft). Postoperative coronary arteriography revealed obstruction of the mid-LAD (which had not been detected before the operation and may have been induced by insertion of the probe), as well as the successful grafting of the Y-shaped saphenous vein graft to both sides of the obstruction (Fig. 4). The perfusion area of this Y-shaped graft was the anteroseptal and anterior regions of the left ventricle, as determined by transthoracic echocardiography (model 65A ultrasound system, Toshiba Corporation, Tokyo, Japan) (Fig. 4).
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Fig. 1. Preoperative coronary arteriogram revealed total occlusion of proximal LAD with good collateralcirculation from RCA.
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Fig. 2. The perfusion area of LAD was limited to anteroseptal region through transesophagealechocardiography.
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Fig. 3. Extents and distributions of perfusion areas of coronary arteries selected for bypass grafting. PL, Posterolateral;OM, obtuse marginal; Dx, diagonal.
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Fig. 4. A, Postoperative coronary arteriogram revealed the obstruction of the mid-LAD and successful graftingwith a Y-shaped saphenous vein graft to both sides of the obstruction.B,The perfusion area of the Y-shaped graft included the anteroseptal and anterior regions of the leftventricle through transthoracic echocardiography.
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To evaluate the effectiveness of myocardial revascularization, one must grasp the geometry of graft perfusion during the operation. Intraoperative myocardial contrast echocardiography provides immediate information concerning the extent and distribution of the native coronary artery selected for grafting, with no risk. We assessed the extent and distribution of the perfusion area of the 69 coronary arteries (LAD, 19; diagonal branch, 10; obtuse marginal branch, 8; posterolateral branch, 14; RCA, 18) selected for individual bypass grafting on a cross-sectional view obtained at the papillary muscle level of the left ventricle (Fig. 3). The distribution of regional myocardial perfusion was defined from the area of myocardium enhanced by the contrast agent, and the extent of the area of revascularized myocardium was quantified by means of the ratio of its circumference between the enhanced borders to a full circle depicted on the cross-sectional view of the left ventricle. In this case, the geometry of graft perfusion to the RCA was appropriate. However, that to the LAD was small and encompassed only the anteroseptal wall, which indicated that only septal branches were revascularized. Accordingly, we decided that this graft was inappropriate and we regrafted to the LAD, achieving good results.
We think we could estimate the extent and distribution of revascularized myocardium before the operation by comparing the aforementioned results and the findings of the preoperative coronary arteriogram. Such conjecture would be of some help in deciding surgical indications for myocardial revascularization. However, individual architecture of the coronary artery is not always the same and precise assessment is difficult.
Moreover, in this analysis of regional perfusion used cross-sectional views obtained at the papillary muscle, which is the most commonly recorded view. Therefore the perfusion area throughout the whole left ventricle may not be reflected. In the future, we plan to use echo views from all angles in making our assessment.
References
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Kabas JS, Kisslo J, Flick CL, et al. Intraoperative perfusion contrast echocardiography: initial experience during coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1990;99:536-42.[Abstract]
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Mudra H, Zwehl W, Klauss V, et al. Intraoperative myocardial contrast echocardiography for assessment of regional bypass perfusion. Am J Cardiol 1990;66:1077-81.[Medline]
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Hirata N, Nakano S, Taniguchi K, et al. Assessment of regional and transmural myocardial perfusion using myocardial contrast echocardiography during coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1992;104:1158-66.[Abstract]
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Hirata N, Nakano S, Shimazaki Y, et al. Assessment of the size and distribution of the coronary artery selected for bypass grafting using myocardial contrast echocardiography during coronary artery bypass surgery. J Jpn Assoc Thorac Surg 1992;40:13-9.
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N. Hirata, Y. Shimazaki, S. Nakano, K. Sakai, S. Sakaki, and H. Matsuda
Evaluation of regional myocardial perfusion in areas of old myocardial infarction after revascularization by means of intraoperative myocardial contrast echocardiography
J. Thorac. Cardiovasc. Surg.,
December 1, 1994;
108(6):
1119 - 1124.
[Abstract]
[Full Text]
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