HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Beat H. Walpoth Thierry P. Carrel Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Walpoth, B. H. Articles by Carrel, T. P. Search for Related Content PubMed PubMed Citation Articles by Walpoth, B. H. Articles by Carrel, T. P.

Eur J Cardiothorac Surg 1999;15:795-802
© 1999 Elsevier Science NL

Evaluation of coronary bypass flow with color-Doppler and magnetic resonance imaging techniques: comparison with intraoperative flow measurements

Department of Cardiovascular Surgery, Radiology and Cardiology, University Hospital Insel, Bern, Switzerland

Received 19 October 1998; received in revised form 17 February 1999; accepted 11 March 1999.

Corresponding author. Tel.: +41-31-632-23-73/632-23-75; fax + 41-31-632-97-66/382-02-79
e-mail: beat.walpoth{at}insel.ch

	Abstract

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
Objectives: After coronary artery bypass surgery, patency and flow assessment is based on invasive methods such as angiography and intravascular ultrasound or flow wire techniques. The aim of the study was to compare intraoperative transit time flow measurements of coronary bypass grafts with early postoperative color-Doppler and MR-imaging assessment. Methods: In 22 patients (62±8.5 years) undergoing elective coronary bypass surgery the flow was measured in all internal mammary artery grafts (IMA) and saphenous vein grafts using the transit time flow technique. Postoperatively (days 5–7) all patients had a color-Doppler IMA graft assessment followed by a MR-angiography and flow measurement (navigator echo phase contrast technique with and without contrast bolus application) to determine patency and graft flow. Results: Data are expressed as the mean±SD). (1) In all patients the left IMA graft to the left anterior descending coronary artery (LAD) could be identified and flow could be assessed with both color-Doppler and MRI. Venous grafts could only be visualized by MRI. The use of an intravenous contrast bolus enhanced the visualization of coronary artery bypass grafts. (2) The mean IMA to LAD flow was 33±17 ml/min intraoperatively by transit time and postoperatively 36±25 ml/min by MR respectively 66±54 ml/min by color-Doppler technique. (3) The systolic/diastolic flow ratio was 0.44±0.12 intraoperatively and 0.43±0.17 postoperatively by MR respectively 0.67±1.0 by color-Doppler. (4) A statistically significant correlation could be demonstrated between intraoperative transit time and postoperative MR flow measurements (r=0.57; P<0.04), whereas the correlations to color-Doppler flow were poor. Postoperatively MR and color-Doppler showed a good correlation of systolic/diastolic flow ratio (r=0.88; P<0.008). Conclusions: The color-Doppler method during echocardiography and MR-imaging are useful non-invasive techniques to visualize postoperative IMA grafts for patency assessment. The quantification of IMA flow is still difficult with either technique, but MR flow measurements showed the best correlation to the intraoperatively measured transit time flow. The MR technique is the most promising non-invasive method for postoperative evaluation of coronary bypass grafts, since it allows visualization and reliable flow quantification.

Key Words: Coronary graft • Blood flow • Color-Doppler • Transit time • MR angiography • MR flow

	1. Introduction

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
Low coronary flow in coronary artery bypass graft (CABG) represents a major problem for perioperative infarction and postoperative survival [1–4]. Thus, measurements of coronary bypass flow during CABG may be helpful to detect technical failures, coronary vasospasm or graft insufficiency for correction of the low flow situation while the chest is still open [5–8].

Non-invasive flow measurements in the early postoperative phase are difficult and associated with a low sensitivity and a high variability such as color-Doppler flow measurements and MR-phase contrast flow mapping [9–15]. Thus, the purpose of the present study was to determine intraoperative flow by the transit time flow technique and to compare these measurements to postoperative (days 5–7) flow measurements obtained by color-Doppler echocardiography and phase contrast MR-flow measurements.

	2. Method and patients

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
In 22 male patients, mean age 62±8.5 years, scheduled for elective CABG, intraoperative flow measurements were performed. All patients had a normal or slightly reduced ejection fraction (64±12%) and were non-diabetic. All received a left internal mammary artery (IMA) graft to the left anterior descending artery (LAD) using standard cardiopulmonary bypass techniques with mild hypothermia and cold blood cardioplegia. In all patients additional saphenous vein grafts were implanted. The total number of distal venous and arterial grafts was 2.8±0.4 per patient. All patients had an uneventful postoperative course. Informed consent was obtained from all patients.

2.1. Intraoperative flow measurements
Transit time volume flow measurements (CardioMed 4008, Medi-Stim, Norway) were carried out 15 min after weaning from cardiopulmonary bypass (CPB) before chest closure [5,6]. No vasocative drugs were given before the measurements. The size of the flow probe was either 4 or 5 mm in diameter. Occasionally a 3 mm flow probe was used for measuring the IMA on its partly skeletonized segment. All IMA to LAD grafts and saphenous vein grafts were investigated (n=62). In addition the flow of the native right IMA was determined in three patients as a control measurement. Mean and phasic graft flow as well as arterial blood pressure were measured in all patients (Fig. 1) and systolic/diastolic flow ratio was calculated.

View larger version (48K): [in this window] [in a new window]   Fig. 1. (Patient R.H., 1920) Intra operative transit time flow measurement of the left IMA to LAD graft. The upper panel shows the phasic flow curve with a mean flow of 91 ml/min. The lower panels show curves of the arterial pressure, ECG and the calculated resistance.

View larger version (109K): [in this window] [in a new window]   Fig. 2. (Patient R.H., 1920) Postoperative color-Doppler examination of the left IMA to LAD graft. The curve shows a good signal with a peak velocity (v max) of 0.47 m/s and a mean velocity of 0.20 m/s.

1. Localization of the graft position was performed with a single shot turbo spin echo (HASTE) sequence (5 mm slice thickness) in breath hold technique and ECG triggering (n=16).
   
2. Then, MR-angiography was carried out using a 3D gradient echo fast low angle shot (FLASH) sequence with a section thickness of 1.5 mm after administration of gadolinium-DTPA contrast bolus injection (0.2 mmol/kg BW) (n=10 with contrast and n=6 without contrast). Postprocessing with use of the maximum intensity algorhythm (MIP) allows visualization of the graft in any plane.
   
3. At the end of the examination graft flow measurements were preformed with a navigator echo 2D phase contrast (PC) sequence with about 30 time points (velocity measurements always perpendicular to the graft). The navigator echo tracking allowed to compensate for respiratory motion artifacts by tracking the variations of the dome of the right diaphragm (TR=65, TE=5.0 ms, section thickness 6 mm; VENC=75 cm/s) (n=16). A region of interest (ROI) was placed on the individual grafts and followed (repositioned) in each time point.
   

Patency was assessed visually by a radiologist blinded to the patient' data. Identification of the distal anastomosis was performed from 3D FLASH with MIP reconstruction in all patients. Flow was measured in the midportion of the left IMA to LAD graft. The right IMA flow was measured in the midportion in situ of the right chest wall. The absolute flow was calculated by the multiplication of flow velocity (PC) by the vascular cross-sectional area (Fig. 3) .

View larger version (84K): [in this window] [in a new window]   Fig. 3. (Patient R.H., 1920) Postoperative MR phase contrast flow measurement of the left IMA to the LAD graft. The left panel shows a cross-section through the upper chest from a 2D phase contrast magnitude image after gadolinium DPTA bolus injection (0.2 mmol/kg BW). The left IMA shows a bright flow signal and is circled for area measurement (arrow 1). Note, on the opposite side of the sternum (arrow 2), the native right IMA artery (lateral) and vein (medial). The right panel shows the flow curve of the IMA with 30 time points. A biphasic systolic/diastolic flow curve with a higher diastolic component is shown with a mean flow of 65 ml/min.

	3. Results

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
3.1. Hemodynamics
Intraoperative heart rate was significantly higher than that registered during postoperative MR and color-Doppler flow measurements (Table 1). Mean aortic pressure was slightly lower during bypass surgery although significantly. The rate–pressure product was not significantly different between the three groups in the ANOVA test for repeated measurements. Whereas it was increased significantly intraoperatively when compared to color-Doppler measurements, but not to MR-measurements in a multiple comparison test.

View larger version (38K): [in this window] [in a new window]   Fig. 5. Systolic/diastolic flow ratio in grafted (left columns) and ungrafted (right columns) IMA according to the measuring technique used: intraoperative transit time, postoperative color-Doppler and MR phase contrast. A higher systolic/diastolic flow ratio is measured with all three techniques in the ungrafted native right IMA artery as compared to the left IMA grafted to the LAD showing more diastolic flow due to coronary anastomosis. Color-Doppler yields a relatively high systolic flow pattern probably due to the proximal measurements (2nd intercostal space).

View larger version (126K): [in this window] [in a new window]   Fig. 4. MIP reconstruction of a 3D FLASH sequence after gadolinium injection showing clearly the left IMA to LAD graft, 2 saphenous vein grafts originating at the anterior border of the ascending aorta going to the circumflex coronary artery (left panel: sagital view). The right panel (coronal view) shows one SVG anastomosed to the right coronary artery and the right IMA in situ.

3.5. Correlations
There was a significant correlation between intraoperative direct flow measurements and postoperative MR-flow measurements (r=0.57; P<0.04). A similar but not significant correlation was observed between postoperative MR and color-Doppler flow measurements (r=0.44; P<0.02). However, no correlation existed between intraoperative and color-Doppler measurements. Systolic/diastolic flow ratios correlated between the postoperative color-Doppler and MR-flow measurements (r=0.88; P<0.008). There was a poor correlation between intraoperative and postoperative MR respectively color-Doppler systolic/diastolic flow ratio (Table 3).

	4. Discussion

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

4.1. Intraoperative flow measurements
Intraoperative transit time volume flow measurements have been shown to be accurate and were easy to perform without complications [5,7]. Experimental and clinical studies have shown a close correlation to true blood flow measurements [5,16]. They represent the best quality assessment of the revascularization procedure since technical errors or severe vasospasm can easily be detected and treated [6]. The results of intraoperative flow measurements are not directly comparable with the postoperative results due to the fact that they are not taken simultaneously; however, there is a fair significant correlation of the IMA graft flow between the intraoperative transit time and the postoperative MR techniques. In the few right IMA arteries measured in situ a low flow and high resistance, probably due to vasospasm during preparation, was noted [5,6].

4.2. Color-Doppler flow measurements
Assessment of flow velocity is well established by the color-Doppler method and used routinely for cardiac and vascular evaluations. In measuring coronary bypass flow using color-Doppler technique the main problem is signal penetration, insonation angle and spatial resolution [12,13,17,18].

Color-Doppler flow showed higher values than the other two techniques due to the difficulty in assessing the graft diameter (pixel blurring for vascular area) and the large variation between patients.

There is a high systolic/diastolic flow ratio even in the grafted left IMA, probably due to the fact that the measurements were performed very proximally in the left IMA close to the aorta showing mainly systolic flow characteristics. This may explain the different findings of other authors with predominantly diastolic flow in the IMA grafts [5,6,19].

4.3. MR angiography and flow measurements
MR angiography and flow measurements seem to be the noninvasive technique of choice, especially when using contrast agents since excellent visualization of all grafts and often the distal anastomosis was possible. Flow quantification can be performed at different and multiple levels which is an advantage compared to the color-Doppler technique. Systolic/diastolic flow ratio is comparable to measurements carried out during surgery and shows a higher diastolic than systolic flow, probably due to the fact that measurements were carried out in the mid or the distal portion of the left IMA graft. Measurements performed on native coronary arteries have shown limitations due to the small diameter, motion and tortuosity of native coronary arteries [20]. In contrast, when measuring flow in coronary artery bypass graft, especially saphenous vein grafts, several authors have shown good correlation to other techniques and are confident of such measurements due to the larger size of the vessels. Several authors have shown that such measurements are possible and that flow curves can be obtained reliably [11,14,21].

4.4. Limitations of the study
One major problem of the present study was the non-simultaneous assessment of coronary flow from intraoperative to early postoperative measurements. This fact is reflected by the differences in heart rate, mean aortic pressure and rate–pressure product (Table 1). However, simultaneous assessment of coronary flow by MR-imaging and color-Doppler flow techniques is not possible at the moment because intraoperative MR-possibilities are not available, metallic structures of the flow probes interfere with the MR-signal and because of the patient’s instrumentation (ventilation, multiple perfusors, etc.), monitoring and catheter access in the MR-unit. These limitations apply also for the Doppler flow wire techniques. Thus, a true simultaneous assessment of bypass flow is not possible in the patient and influences the conclusion of this study.

MR-flow measurements are limited by their low temporal and spatial resolution. Motion artifact induced by cardiac contraction and respiration may have affected MR-flow measurements and, thus, its reliability. Despite these motion artifacts MR-measurements showed a significant correlation to the intraoperative flow measurements, whereas the color-Doppler did not (Table 3).

Color-Doppler flow measurements may have been influenced by pixel blurring. As a result vascular area could not be measured exactly and might have led to overestimation of flow.

	5. Summary

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
Comparison of intra, and early postoperative flow measurements indicate the superiority of MR over color-Doppler techniques for assessing IMA graft flow. Color-Doppler flow measurements are associated with considerable over estimation of bypass flow although graft patency could be assessed in all patients.

Intraoperative and early postoperative flow measurements may be helpful for assessing bypass patency and detecting early graft failures and its related morbidity and mortality. Current non-invasive technologies are, however, limited by several problems and may provide information on graft patency rather than quantitative flow measurements.

	Acknowledgments

 
The authors would like to thank the staff of cardiology and radiology for their expert help. This work was partly supported by a grant from the Swiss Heart Foundation.

	Footnotes

 
Presented at the 12th Annual Meeting of the European Association for Cardio-thoracic Surgery, Brussels, Belgium, September 20–23, 1998.

	Appendix A. Conference discussion

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 
Dr Friedrich Mohr (Leipzig, Germany): Does the MR allow for an anastomotic judgment also? It does not look like it on the image, although the images are very nice.

Dr Walpoth: We have even better images, but I just took a random image. Your question is a very important one and we looked at this. Actually, we used only one injection of contrast agent, trying to obtain all the necessary information in one single exam in order to reduce cost and time; in about half of the patients you can see the LIMA to LAD anastomosis. This needs some postprocessing because you have to rotate the heart to be multiplanar and otherwise you have the overlap of the contrast in the left ventricle.

Dr Olaf Wendler (Homburg, Germany): I think you may have a systematic mistake because of correlating the flow measurements intraoperatively with postoperatively. It is known that low peripheral resistance or anemia may cause higher flow rates in the postoperative period.

Dr Walpoth: Well, I agree with you. I mentioned that there is a limitation on trying to compare intra with postoperative flow measurements. I think you cannot compare it since the patients are in a different hemodynamic situation. Nevertheless, we recorded the pressure–rate product, and there was no significant difference between intra and postoperative measurements. However, I cannot make any comment on the peripheral resistance. Thus, there is no way of comparing these two measurements. However, our aim was mainly to see whether we could visualize the graft and whether we could measure flow: those are possible and it turned out that flow values were comparable between intraoperative and postoperative measurements.

Dr Yves Louagie (Mont Yvoir, Belgium): Do you have contraindications to the use of the MRI and gadolinium injection in some patients? Particularly, do you consider that the large clips used to achieve hemostasis of LIMAs and gastroepiploic arteries contraindicate the use of MRI?

Dr Walpoth: Small metallic clips on a IMA or vein grafts are no major problem. Mostly you will have a blackout where your clip is located but can visualize the graft and measure flow above or below that region. Regarding the gadolinium: there are a few contraindications, which are, for instance, renal insufficiency, but otherwise it is used as a single shot and is well tolerated by the patient.

	References

Top Abstract 1. Introduction 2. Method and patients... 3. Results 4. Discussion 5. Summary Appendix A. Conference... References

 

1. Barner H.B. Coronary flow reserve: physiologically important, operatively altered, and clinically emerging. Ann Thorac Surg 1988;45:469-470.[Medline]
2. Alderman E.L. Angiographic correlates of graft patency and relationship to clinical outcomes. Ann Thorac Surg 1996;62(5):S22-S25.
3. Carrel T., Kujawski T., Zünd G., Schwitzer J., Amann F.W., Gallino A., Bertel O., Jenni R., Turina M. The internal mammary artery malperfusion syndrome: incidence, treatment, and angiographic verification. Eur J Cardiothorac Surg 1995;9:190-197.[Abstract]
4. Huddleston C.B., Stoney W.S., Alford J.r., W C., Burrus G.R., Glassford D.M., Jr, Lea J.W., Petracek M.R., Thomas C.S., Jr Internal mammary artery grafts: technical factors influencing patency. Ann Thorac Surg 1986;42:543-549.[Abstract]
5. Walpoth B.H., Mohadjer A., Gersbach P., Rogulenko R., Walpoth B.N., Althaus U. Intraoperative internal mammary artery transit-time flow measurements: comparative evaluation of two surgical pedicle preparation techniques. Eur J Cardio-thorac Surg 1996;10:1064-1070.[Abstract]
6. Walpoth B.H., Bosshard A., Genyk I., Kipfer B., Berdat P.A., Hess O.M., Althaus U., Carrel T.P. Transit time flow measurement for detection of early graft failure during myocardial revascularization. Ann Thorac Surg 1998;66:1097-1100.[Abstract/Free Full Text]
7. Canver C.H.C., Dame N.A. Ultrasonic assessment of internal thoracic artery graft flow in the revascularized heart. Ann Thorac Surg 1990;58:135-138.[Abstract]
8. Louagie Y.A., Haxhe J.P., Buche M., Schoevaerdts J.C. Intraoperative electromagnetic flowmeter measurements in coronary artery bypass grafts. Ann Thorac Surg 1994;57(2):357-364.[Abstract]
9. Caretta Q., Voci P., Bilotta F., Mercanti C., Marino B. Intraoperative detection of coronary artery graft occlusion by myocardial contrast echocardiography. J Cardiothorac Vasc Anesth 1994;8(2):206-208.[Medline]
10. Vrachliotis T.G., Bis K.G., Aliabadi D., Shetty A.N., Safian R., Simonetti O. Contrast-enhanced breath-hold MR angiography for evaluating patency of coronary artery bypass grafts. Am J Roentgenol 1997;168(4):1073-1080.[Abstract/Free Full Text]
11. Hoogendoorn L.I., Pattynama P.M., Buis B., van der Geest R.J., van der Wall E.E., de Roos A. Noninvasive evaluation of aortocoronary bypass grafts with magnetic resonance flow mapping. Am J Cardiol 1995;75(12):845-848.[Medline]
12. Segadal L., Matre K., Engedal H., Resch F., Grip A. Estimation of flow in aortocoronary grafts with a pulsed ultrasound Doppler meter. Thorac Cardiovasc Surg 1982;30(5):265-268.[Medline]
13. Bilgen F., Alhan C., Alhan S., Idiz M., Demiray E., Ozler A. Use of color Doppler imaging in assessment of preoperative and postoperative flow characteristics of internal thoracic artery in myocardial revascularization. Angiology 1996;47(6):589-594.
14. Rebergen S.A., van der Wall E.E., Doornbos J., de Roos A. Magnetic resonance measurement of velocity and flow technique validation and cardiovascular applications. Am Heart J 1993;126(6):1439-1456.[Medline]
15. Rubinstein R.I., Askenase A.D., Thickman D., Feldman M.S., Agarwal J.B., Helfant R.H. Magnetic resonance imaging to evaluate patency of aortocoronary bypass grafts. Circulation 1987;76(4):786-791.[Abstract/Free Full Text]
16. Laustsen J., Pedersen E.M., Terp K., Steinbrüchel D., Kure H.H., Paulsen P.K., Jorgensen H., Paaske W.P. Validation of a new transit time ultrasound flowmeter in man. Eur J Vasc Endovasc Surg 1996;12:91-96.[Medline]
17. DeBono D.P., Samani N.J., Spyt T.J., Hartshorne T., Thrush A., Evans D.H. Transcutaneous ultrasound measurement of blood-flow in internal mammary artery to coronary artery grafts. Lancet 1992;339:379-381.[Medline]
18. Crowley J.J., Shapiro L.M. Noninvasive assessment of left internal mammary artery graft patency using transthoracic echocardiography. Circulation 1995;92(II):II25-II30.
19. Louagie Y.A.G., Haxhe J.P., Jamart J., Gurne O., Buche M., Schoevaerdts J.C. Perioperative hemodynamic study of left internal mammary artery grafts. Thorac Cardiovasc Surg 1995;43:27-34.[Medline]
20. Mueller M.F., Fleisch M., Kroeker R., Chatterjee T., Meier B., Vock P. Proximal coronary artery stenosis: three-dimensional MRI with fat saturation and navigator echo. J Magn Reson Imaging 1997;7(4):644-651.[Medline]
21. Galjee M.A., van Rossum A.C., Doesburg T., Hofman M.B., Falke T.H., Visser C.A. Quantification of coronary artery bypass graft flow by magnetic resonance phase velocity mapping. Magn Reson Imaging 1996;14(5):485-493.[Medline]

This article has been cited by other articles:

				W. Hassanein, A. A. Albert, B. Arnrich, J. Walter, I. C. Ennker, U. Rosendahl, S. Bauer, and J. Ennker Intraoperative Transit Time Flow Measurement: Off-Pump Versus On-Pump Coronary Artery Bypass Ann. Thorac. Surg., December 1, 2005; 80(6): 2155 - 2161. [Abstract] [Full Text] [PDF]

				J.M. Hartman, J.C. Kelder, R.G.A. Ackerstaff, F.E.E. Vermeulen, and A.J.J.C. Bogers Differences in LIMA Doppler characteristics for different LAD perfusion areas Eur. J. Cardiothorac. Surg., December 1, 2001; 20(6): 1135 - 1141. [Abstract] [Full Text] [PDF]

				P. Massoudy, A. Szabo, H. J.C.M. van de Wal, and H. Jakob Intraoperative flow measurement of native coronary artery can help decision making before CABG Eur. J. Cardiothorac. Surg., December 1, 2001; 20(6): 1261 - 1263. [Abstract] [Full Text] [PDF]

				N. Ishida, H. Sakuma, B. P. Cruz, T. Shimono, T. Tokui, I. Yada, K. Takeda, and C. B. Higgins MR Flow Measurement in the Internal Mammary Artery-to-Coronary Artery Bypass Graft: Comparison with Graft Stenosis at Radiographic Angiography Radiology, August 1, 2001; 220(2): 441 - 447. [Abstract] [Full Text] [PDF]

				T. Hirotani, T. Kameda, S. Shirota, and Y. Nakao An evaluation of the intraoperative transit time measurements of coronary bypass flow Eur. J. Cardiothorac. Surg., June 1, 2001; 19(6): 848 - 852. [Abstract] [Full Text] [PDF]

				G. D'Ancona, M. Ricci, J. Bergsland, T. A. Salerno, and H. L. Karamanoukian Graft Patency Verification in Coronary Artery Bypass Grafting: Principles and Clinical Applications of Transit Time Flow Measurement Angiology, September 1, 2000; 51(9): 725 - 731. [Abstract] [PDF]

				G. D'Ancona, H. L. Karamanoukian, M. Ricci, S. Schmid, J. Bergsland, and T. A. Salerno Graft revision after transit time flow measurement in off-pump coronary artery bypass grafting Eur. J. Cardiothorac. Surg., March 1, 2000; 17(3): 287 - 293. [Abstract] [Full Text] [PDF]

				L. Wiklund, M. Johansson, G. Brandrup-Wognsen, M. Bugge, G. Radberg, and E. Berglin Difficulties in the interpretation of coronary angiogram early after coronary artery bypass surgery on the beating heart Eur. J. Cardiothorac. Surg., January 1, 2000; 17(1): 46 - 51. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Beat H. Walpoth Thierry P. Carrel Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Walpoth, B. H. Articles by Carrel, T. P. Search for Related Content PubMed PubMed Citation Articles by Walpoth, B. H. Articles by Carrel, T. P.