Interactive Cardiovascular and Thoracic Surgery 1:52-54(2002)
© 2002 European Association of Cardio-Thoracic Surgery
Real-time three-dimensional echocardiography evaluation of graft anastomoses during coronary artery bypass grafting: preliminary experience
Yoshihiro Suematsu*,
Shinichi Takamoto and
Toshiya Ohtsuka
Department of Cardiothoracic Surgery, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8655, Japan
* Corresponding author. Tel.: +81-3-5800-8654; fax: +81-3-5684-3989
suematsu{at}aurora.dti.ne.jp
Received March 27, 2002;
received in revised form July 12, 2002;
accepted July 15, 2002
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Abstract
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Three-dimensional echocardiography has been intensively developed recently, and it is expected to overcome the limitations of two-dimensional echocardiography. We describe the usefulness of our original real-time three-dimensional system for evaluating graft anastomoses during coronary artery bypass grafting operations.
Key Words: Coronary artery bypass; Three-dimensional echocardiography; Graft anastomose
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1. Introduction
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We previously demonstrated that two-dimensional echocardiography (2DE) provides meaningful information on the target coronary artery and enables detection of technical errors and inadequacies during bypass surgery [1]. However, the imaging technique of 2DE is time-consuming, because all planes are not imaged simultaneously. Moreover, sonographers need additional technical skills to be able to acquire and evaluate the two-dimensional images. Over the last few decades, three-dimensional echocardiography (3DE) has been intensively developed, with several different approaches having used to acquire and reconstruct ultrasound data in three dimensions, and 3DE is now expected to overcome the limitations of 2DE [2]. Recently, we developed an original real-time 3DE system that reconstructs the power Doppler signals obtained from 2DE into three-dimensional image data sets without any time delay. In this paper, we describe the usefulness of this novel system for evaluating graft anastomosis during coronary artery bypass grafting.
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2. Technique
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An original real-time imaging system using 3DE that has a specific high-speed image rendering unit for three-dimensional data has been developed. The system provides three-dimensional images at the rate of 25 images per second and allows organs to be observed from any direction desired. A magnetic sensor system (Ascension Technology Corporation, VT, USA) is used to detect the position of the ultrasonic transducer. The sensor system consists of a transmitter to generate a magnetic field and a receiver to detect the position. The receiver is mounted on the transducer, and the transmitter is placed under a surgical operating table. The distance between the receiver and the transmitter affects the accuracy of position detection, with shorter distances yielding greater accuracy. Several sectional images obtained by ultrasound power Doppler with ultrasound machine SSD-5500 (Aloka Co., Ltd., Tokyo, Japan) and information on three-dimensional positions from the magnetic sensor are simultaneously transferred to the three-dimensional system and used to produce 3DE images in real time. The imaging probe is 39mm long and has a 36x10mm2 contact surface and a scanning frequency of 13MHz. It has a depth of field of 2.0cm and a two-point phantom resolution of 0.1mm, and it can be sterilized by standard ethylene oxide techniques.
We assessed 12 saphenous vein grafts among 16 bypass grafts in five consecutive patients who underwent conventional coronary artery bypass grafting with cardiopulmonary bypass (three patients), or off-pump coronary artery bypass grafting (two patients). The left internal mammary artery was used in four patients. Quadruple bypass was performed in one of the patients, and triple bypass in four of the patients. The average age of the patients was 64.2±9.3 years (range: 54–79 years); there was one female and four males. All proximal anastomoses except the left internal mammary artery were evaluated with our 3DE system under water-filled conditions after the completion of all anastomoses.
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3. Results
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High quality echocardiographic images were easily obtained within 3min in patient studies by using the approach described above. After all of the data had been obtained, the operator could evaluate the 3D images on the display from any directions desired. As a result, there were no blind spots, all grafts could be evaluated, and the spatial relations of each graft were clearly understood. Fig. 1 shows images of the four saphenous vein grafts anastomosed to the ascending aorta in the quadruple bypass patient, and Fig. 2 shows the same image from a different angle. No graft failure was observed on the 3D images, and the success of the grafts was confirmed by postoperative angiography. No complications related to epicardial imaging occurred, such as coronary vessel injury or compromise, hemodynamic disturbances, infection, or electrical or mechanical injuries.
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Fig. 1 Three-dimensional echocardiographic image showing four saphenous vein grafts (1–4) anastomosed to the ascending aorta (Asc. Ao) during coronary artery bypass grafting.
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Fig. 2 The same three-dimensional echocardiographic image from a different angle. Saphenous vein grafts (1–4); Asc. Ao, ascending aorta.
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4. Comments
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Since technical errors during graft anastomosis may play a role in early graft occlusion after coronary artery bypass surgery, it is important to devise a reliable method of assessing anastomoses. Coronary angiography is generally considered the ‘gold standard’ for detecting technical errors in graft anastomoses, but it is invasive, costly, time consuming, and not always readily available in the operating room. Other methods such as thermal coronary artery imaging with an infrared camera [3] or flow measurement techniques [4], have frequently been employed for intraoperative assessment of the quality of anastomoses during bypass surgery, but their sensitivity and quality are still not acceptable. Hiratzka et al. [5] and the authors [1] previously demonstrated that intraoperative high-frequency epicardial echocardiography is a powerful tool that allows accurate measurement of coronary arterial bypass graft anastomoses and has been found to enable detection of technical errors during conventional and off-pump coronary artery bypass operations. This 2DE imaging technique is a promising approach, but it is time-consuming because all planes are not imaged simultaneously. In addition, sonographers need additional technical skills to aquire and evaluate the two-dimensional images. 3DE is therefore expected to overcome these limitations of 2DE. On the other hand, this technique does have some limitations. Three-DE images are based on power Doppler, and the evaluation of distal anastomoses in off-pump coronary artery bypass grafting is difficult because of the beating heart. Therefore, the time resolution must be improved to enable the visualization of distal anastomoses. Such technical improvements would make the 3DE imaging system an even more powerful tool for use during coronary artery bypass grafting.
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Appendix A
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ICVTS on-line discussion
Author: Dr. Carlos-A Mestres Cardiovascular Surgery, Hospital Clinico. University of Barcelona, Villarroel 170, Barvelona, Spain
Date: 12-Aug-2002 00:54
Message: The authors should be congratulated in their efforts looking for an accurate method of intraoperative visualization of coronary grafts. No doubt all of us practising surgeons wish to have intraoperative evidence that the grafts we have constructed are actually working before leaving the operating room. We also know that it is almost impossible to have a postoperative predischarge angiographic evidence of how the grafts work. Although just a handful of teams are able to perform any kind of so-called "hybrid procedures" with or without intraoperative angiography, a solution like 3D-echo could be considered an interesting and promising approach. The experience reported by the authors is still scanty but it may open the door for future technological refinement that could lead to a routine intraoperative assessment of coronary grafts.
PII: S1569929302000117
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References
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- Suematsu Y, Takamoto S, Ohtsuka T. Intraoperative echocardiographic imaging of coronary arteries and graft anastmoses during coronary artery bypass grafting without cardiopulmonary bypass. J Thorac Cardiovasc Surg. 2001;122:1147–1154[Abstract/Free Full Text]
- Keller AM. Positional localization: three-dimensional transthoracic echocardiographic techniques for the measurement of cardiac mass, volume, and function. Echocardiography. 2000;17:745–748[Medline]
- Suma H, Isomura T, Horii T, Sato T. Intraoperative coronary artery imaging with infrared camera in off-pump CABG. Ann Thorac Surg. 2000;70:1741–1742[Abstract/Free Full Text]
- Jaber SF, Koenig SC, Bhasker Rao B, Van Himbergen DJ, Cerrito PB, Ewert DJ, Gray LA Jr, Spence PA. Role of graft flow measurement technique in anastomotic quality assessment in minimally invasive CABG. Ann Thorac Surg. 1998;66:1087–1092[Abstract/Free Full Text]
- Hiratzka LF, McPherson DD, Brandt B 3rd, Lamberth WC Jr, Sirna S, Marcus ML, Kerber RE. The role of intraoperative high-frequency epicardial echocardiography during coronary artery revascularization. Circulation. 1987;76:V33–V38
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Abstract
1. Introduction