- Email: [email protected]
Angiographic demonstration of no-flow anatomical patency of internal thoracic-coronary artery bypass grafts
Angiographic Demonstration of No-Flow Anatomical Patency of Internal Thoracic-Coronary Artery Bypass Grafts Soichiro Kitamura, MD, Kanji Kawachi, MD, Toshio Seki, MD, Noriyoshi Sawabata, MD, Ryuichi Morita, MD, and Tetsuji Kawata, MD Department of Surgery 111, Nara Medical College, Nara, Japan
To clarify the no-flow situation of the stringlike internal thoracic artery graft, we angiographicallyexamined such grafts by temporarily occluding the recipient coronary artery with a percutaneous transluminal coronary angioplasty balloon and were able to reveal anatomical patency of the internal thoracic artery graft in 2 patients l year and 3 years after the operations. Thus, there is a possibility that internal thoracic artery grafts may con-
tinuously maintain anatomical patency even under noflow situations just like nonfunctioningcollateral vessels and may function properly later as a graft when the native coronary flow decreases. Also, this angiographic technique can be a new method for detecting anatomical patency of no-flow and functionally closed internal thoracic artery grafts. (Ann Thoruc Surg 2992;53:256-9)
I
both patients after the operation, stenosis of the LAD was apparently improved (less than 25% in each case) with substantial regression of atheromatous plaque, and ITA grafts showed thinning longitudinally, a string sign, as shown in Figures l a and 2a. Flow of the contrast material from the ITA to the LAD was not demonstrable in either patient, and the grafts were judged at least functionally closed. At this moment, we explained the situation to the patients and obtained full consent for further angiographic examinations with the use of a percutaneous transluminal coronary angioplasty balloon. Native flow in the LAD was temporarily interrupted by occluding the LAD with a percutaneous transluminal coronary angioplasty balloon, then ITA angiography was repeated. As shown in Figures l b and 2b, the flow from the stringlike ITA into the LAD was now clearly observable. When native flow was intercepted, the bloodstream from ITA to LAD increased and the anatomical patency of ITA grafts could be demonstrated on angiographic images.
t is known that some internal thoracic artery (ITA) grafts become very thin and exhibit a so-called string sign with no demonstrable flow of the contrast material into the recipient coronary artery. However, the question how such an ITA graft will change with time or whether the graft can maintain its anatomical patency continuously for a long time has not yet been answered. We angiographically demonstrated anatomical patency of the ITA graft in spite of its string sign with no-flow situation in 2 patients 1 and 3 years after the operations by virtue of temporary occlusion of native coronary blood flow using the balloon of a percutaneous transluminal coronary angioplasty catheter. Two male patients, 64 and 50 years old, underwent coronary artery bypass grafting with an ITA in situ anastomosed to the left anterior descending coronary artery (LAD). Preoperatively, they had angina pectoris and their coronary arteriography was judged to show 95% and 75% stenosis in the LAD. Single left ITA grafting was performed to the LAD in 1patient and quadruple grafting including a right ITA to the LAD was carried out in the other patient. The internal diameter of the ITA was approximately 2.0 mm in each patient. After the operation, the patients have not been aware of any angina pectoris, and myocardial ischemia in the LAD region was not observed by exercise electrocardiography or 201thalium scintigraphic examinations. Three years and 1 year after the operations, coronary arteriography was repeated to confirm patency of each graft, although the patients were both asymptomatic. In Accepted for publication July 24, 1991 Address reprint requests to Dr Kitamura, Department of Surgery 111, Nara Medical College, 840 Shijo-cho, Kashihara, Nara, Japan634.
0 1992 by The Society of Thoracic Surgeons
Comment Various causes of ITA graft longitudinal thinning have been put forth as follows: (1)competitive flow phenomenon in which ITA flow decreases because of flow competition with unimpeded native coronary flow [la];(2) steal phenomenon in which, if a large branch of the ITA remains undivided, the flow after bifurcation of this branch decreases and the ITA becomes thinned [4]; (3) ITA spasm [5]; (4) circumferentialinflammation of the ITA in postpericardiotomy syndrome [5]; and (5) bums of the ITA caused by electrocautery [5]. Among them, we consider the thinning of ITA graft to be mainly caused by flow competition when a stenotic lesion of the recipient vessel is mild or regressed, and also when myocardial ischemia 0003-4975/92/$3.50
CASE REPORT KITAMURAET AL NO-FLOW ANATOMICAL PATENCY OF ITA G M
Ann Thorac Surg 1%2;53156-9
157
e
m
.5 3
Anterior View
Lateral View
Fig 1. (Patient 1.) (a) Postoperative (3 years) left internal thoracic arteriography showed a string sign of the graft with no inflow of contrast medium into the left anterior descending artery (no-flow situation). (b) With temporary occlusion of the proximal left anterior descending artery (LAD) by a percutaneous transluminal coronary angioplasty balloon (BC), left internal thoracic arteriography now demonstrated inflow of the contrast material into the coronary artery, revealing anatomical patency of the no-flow internal thoracic artery graft (IMA).
158
Ann Thorac Surg 1992;53:156-9
CASE REPORT KITAMURA ET AL NO-FLOW ANATOMICAL PATENCY OF ITA GRAFT
Fig 2. (Patient 2.) (a) A stringlike left internal thoracic artey graft with no-flow into the left anterior descending artery. (b) Repeated left internal thoracic arteriography now showing anatomical patency of the graft, demonstrated by temporay occlusion of the recipient left anterior descending artey with a percutaneous transluminal coronay angioplasty balloon.
in the relevant region is absent. Dincer and Barner [ l ] reported a case wherein the ITA graft became patent again in the angiographic examination 4 years after the operation when the LAD lesion had progressed from 80% to 95%, although it was not angiographically patent 1 year after the operation. Aris and co-workers [2] and we [6] also reported similar cases in that ITA grafts were judged nonpatent in the early postoperative angiograms, but late after the operation, the ITA graft became patent in accordance with the progressing stenosis of the bypassed coronary artery. In our 2 patients, it is thought that blood flow of the ITA graft was markedly reduced due to unimpeded native LAD flow (flow competition between ITA and LAD) resulting in the so-called string phenomenon. Because inflow of contrast medium from the ITA to the LAD was not able to be proved by usual angiography, these ITA grafts were considered to be closed. However, we could demonstrate the anatomical patency of the no-flow ITA graft by angiography when we temporarily occluded native coronary artery flow with a percutaneous transluminal coronary angioplasty balloon. Therefore, the ITA graft involved was apparently in the situation where antegrade graft flow was hardly present; namely, the graft was functionally closed (no-flow situation) but anatomically patent just like a regressed collateral vessel. We believe that this angiographic technique can be a new method for detecting anatomical patency of the functionally closed ITA graft, although it should be carried out with caution. Our present cases showed regression of LAD lesions postoperatively. Regression of coronary artery stenotic lesions has been demonstrated by repeated angiography in 15 of 317 patients (4.7%)in one series [7] and in 7 of 227 patients (3.1%)in another series [8]. We have seen ITA grafts in no-flow situations in 5 of the 142 (3.5%)consec-
utive grafts evaluated by postoperative angiography. This incidence was quite similar to that reported for regression of coronary lesions [7, 81. Because we have not performed angiography with temporary closure of the recipient coronary artery in all patients, we do not know the true incidence of no-flow but anatomically patent ITA grafts. However, two of the three grafts thus tested maintained anatomical patency. Therefore, we believe that the incidence of no-flow but anatomically patent ITA grafts is not low. No signs of ischemia in the relevant region were observed either in clinical symptoms or by myocardial scintigraphic examinations. Thus, the blood flow through the native coronary artery that showed regression of a stenotic lesion was considered sufficient to make the ITA graft unnecessary and make the ITA graft undergo the string phenomenon. It should be stressed from our observation that the no-flow ITA graft maintained its anatomical patency for a period of 3 years in patient l and l year in patient 2. As previously described [I, 2, 61 it is possible that stringlike and no-flow ITA grafts can enlarge and become functionally patent again when stenosis of the bypassed coronary artery is advanced in certain patients in whom technical problems of anastomosis including graft injury during dissection [5] can be ruled out. The ITA graft in situ is thought to have functioned as an operatively prepared collateral vessel.
References 1. Dincer B, Barner HB. The "occluded" internal mammary artery graft. Restoration of patency after apparent occlusion associated with progression of coronary disease. J Thorac Cardiovasc Surg 1983;85:318-20. 2. Aris A, Borras X, Ramio J. Patency of internal mammary artery grafts in no flow situations. J Thorac Cardiovasc Surg 1987;93: 624.
Ann Thorac Surg 1W2;53156-9
3. Bamer HB. Double internal mammary-coronary artery bypass. Arch Surg 1974;109:627-30. 4. JA. Internal mammary artery-coronary artery mt anastomosis. Influence of the branches on surgical result. J Thorac Cardiovasc Surg 1981;82:909-14. 5. Mills NL, Ochsner JL. Technique of internal mammary-tocoronary artery bypass. Ann Thorac Surg 1974;1723746. 6. Kitamura S, Seki T, Kawachi K, et al. Excellent patency and growth potential of internal mammary artery grafting in
CASE REPORT KITMURA ET AL NO-FLOW ANATOMICAL PATENCY OF ITA GRAW
159
pediatric coronary artery bypass surgery: new evidence for a live conduit. Circulation 1988;78(Suppl 1):129-39. 7. Bruschke AVG, Wijers TS, Kolster W, et al. The anatomic evolution of coronary artery disease demonstrated corenary arteriography in 256 nonoperated patients’ 1981;63:527-36. 8. Ishikawa H, Uwatoko M, Watabe S , et al. Analysis of the evolution of coronary artery disease. Jpn Circ J 1986;50:57586.
INVITED COMMENTARY This report further corroborates previous observations suggesting the physiologic potential of the internal thoracic artery to dilate and contract depending on demand. If corroborated, this should reduce the surgeon’s concern about using the internal thoracic artery grafts in competitive flow situations. Further, it should encourage angiographers to investigate the potential of this test for evaluating patients with a string sign before reoperation. It is conceivable that a substantial proportion of the patients with a string sign do not need to have the conduit replaced at the time of reoperation or may not need the reoperation at all. Such observations could have major
implications on the angiographic indications for and the planning and the execution of a reoperation. It is hoped that the angiographers will further evaluate the usefulness of this technique. Delos M . Cosgrove Ill, M D Department of Thoracic and Cardiovascular Surgery The Cleveland Clinic Foundation One Clinic Center 9500 Euclid Ave Cleveland, OH 441 95-5066
To clarify the no-flow situation of the stringlike internal thoracic artery graft, we angiographicallyexamined such grafts by temporarily occluding the recipient coronary artery with a percutaneous transluminal coronary angioplasty balloon and were able to reveal anatomical patency of the internal thoracic artery graft in 2 patients l year and 3 years after the operations. Thus, there is a possibility that internal thoracic artery grafts may con-
tinuously maintain anatomical patency even under noflow situations just like nonfunctioningcollateral vessels and may function properly later as a graft when the native coronary flow decreases. Also, this angiographic technique can be a new method for detecting anatomical patency of no-flow and functionally closed internal thoracic artery grafts. (Ann Thoruc Surg 2992;53:256-9)
I
both patients after the operation, stenosis of the LAD was apparently improved (less than 25% in each case) with substantial regression of atheromatous plaque, and ITA grafts showed thinning longitudinally, a string sign, as shown in Figures l a and 2a. Flow of the contrast material from the ITA to the LAD was not demonstrable in either patient, and the grafts were judged at least functionally closed. At this moment, we explained the situation to the patients and obtained full consent for further angiographic examinations with the use of a percutaneous transluminal coronary angioplasty balloon. Native flow in the LAD was temporarily interrupted by occluding the LAD with a percutaneous transluminal coronary angioplasty balloon, then ITA angiography was repeated. As shown in Figures l b and 2b, the flow from the stringlike ITA into the LAD was now clearly observable. When native flow was intercepted, the bloodstream from ITA to LAD increased and the anatomical patency of ITA grafts could be demonstrated on angiographic images.
t is known that some internal thoracic artery (ITA) grafts become very thin and exhibit a so-called string sign with no demonstrable flow of the contrast material into the recipient coronary artery. However, the question how such an ITA graft will change with time or whether the graft can maintain its anatomical patency continuously for a long time has not yet been answered. We angiographically demonstrated anatomical patency of the ITA graft in spite of its string sign with no-flow situation in 2 patients 1 and 3 years after the operations by virtue of temporary occlusion of native coronary blood flow using the balloon of a percutaneous transluminal coronary angioplasty catheter. Two male patients, 64 and 50 years old, underwent coronary artery bypass grafting with an ITA in situ anastomosed to the left anterior descending coronary artery (LAD). Preoperatively, they had angina pectoris and their coronary arteriography was judged to show 95% and 75% stenosis in the LAD. Single left ITA grafting was performed to the LAD in 1patient and quadruple grafting including a right ITA to the LAD was carried out in the other patient. The internal diameter of the ITA was approximately 2.0 mm in each patient. After the operation, the patients have not been aware of any angina pectoris, and myocardial ischemia in the LAD region was not observed by exercise electrocardiography or 201thalium scintigraphic examinations. Three years and 1 year after the operations, coronary arteriography was repeated to confirm patency of each graft, although the patients were both asymptomatic. In Accepted for publication July 24, 1991 Address reprint requests to Dr Kitamura, Department of Surgery 111, Nara Medical College, 840 Shijo-cho, Kashihara, Nara, Japan634.
0 1992 by The Society of Thoracic Surgeons
Comment Various causes of ITA graft longitudinal thinning have been put forth as follows: (1)competitive flow phenomenon in which ITA flow decreases because of flow competition with unimpeded native coronary flow [la];(2) steal phenomenon in which, if a large branch of the ITA remains undivided, the flow after bifurcation of this branch decreases and the ITA becomes thinned [4]; (3) ITA spasm [5]; (4) circumferentialinflammation of the ITA in postpericardiotomy syndrome [5]; and (5) bums of the ITA caused by electrocautery [5]. Among them, we consider the thinning of ITA graft to be mainly caused by flow competition when a stenotic lesion of the recipient vessel is mild or regressed, and also when myocardial ischemia 0003-4975/92/$3.50
CASE REPORT KITAMURAET AL NO-FLOW ANATOMICAL PATENCY OF ITA G M
Ann Thorac Surg 1%2;53156-9
157
e
m
.5 3
Anterior View
Lateral View
Fig 1. (Patient 1.) (a) Postoperative (3 years) left internal thoracic arteriography showed a string sign of the graft with no inflow of contrast medium into the left anterior descending artery (no-flow situation). (b) With temporary occlusion of the proximal left anterior descending artery (LAD) by a percutaneous transluminal coronary angioplasty balloon (BC), left internal thoracic arteriography now demonstrated inflow of the contrast material into the coronary artery, revealing anatomical patency of the no-flow internal thoracic artery graft (IMA).
158
Ann Thorac Surg 1992;53:156-9
CASE REPORT KITAMURA ET AL NO-FLOW ANATOMICAL PATENCY OF ITA GRAFT
Fig 2. (Patient 2.) (a) A stringlike left internal thoracic artey graft with no-flow into the left anterior descending artery. (b) Repeated left internal thoracic arteriography now showing anatomical patency of the graft, demonstrated by temporay occlusion of the recipient left anterior descending artey with a percutaneous transluminal coronay angioplasty balloon.
in the relevant region is absent. Dincer and Barner [ l ] reported a case wherein the ITA graft became patent again in the angiographic examination 4 years after the operation when the LAD lesion had progressed from 80% to 95%, although it was not angiographically patent 1 year after the operation. Aris and co-workers [2] and we [6] also reported similar cases in that ITA grafts were judged nonpatent in the early postoperative angiograms, but late after the operation, the ITA graft became patent in accordance with the progressing stenosis of the bypassed coronary artery. In our 2 patients, it is thought that blood flow of the ITA graft was markedly reduced due to unimpeded native LAD flow (flow competition between ITA and LAD) resulting in the so-called string phenomenon. Because inflow of contrast medium from the ITA to the LAD was not able to be proved by usual angiography, these ITA grafts were considered to be closed. However, we could demonstrate the anatomical patency of the no-flow ITA graft by angiography when we temporarily occluded native coronary artery flow with a percutaneous transluminal coronary angioplasty balloon. Therefore, the ITA graft involved was apparently in the situation where antegrade graft flow was hardly present; namely, the graft was functionally closed (no-flow situation) but anatomically patent just like a regressed collateral vessel. We believe that this angiographic technique can be a new method for detecting anatomical patency of the functionally closed ITA graft, although it should be carried out with caution. Our present cases showed regression of LAD lesions postoperatively. Regression of coronary artery stenotic lesions has been demonstrated by repeated angiography in 15 of 317 patients (4.7%)in one series [7] and in 7 of 227 patients (3.1%)in another series [8]. We have seen ITA grafts in no-flow situations in 5 of the 142 (3.5%)consec-
utive grafts evaluated by postoperative angiography. This incidence was quite similar to that reported for regression of coronary lesions [7, 81. Because we have not performed angiography with temporary closure of the recipient coronary artery in all patients, we do not know the true incidence of no-flow but anatomically patent ITA grafts. However, two of the three grafts thus tested maintained anatomical patency. Therefore, we believe that the incidence of no-flow but anatomically patent ITA grafts is not low. No signs of ischemia in the relevant region were observed either in clinical symptoms or by myocardial scintigraphic examinations. Thus, the blood flow through the native coronary artery that showed regression of a stenotic lesion was considered sufficient to make the ITA graft unnecessary and make the ITA graft undergo the string phenomenon. It should be stressed from our observation that the no-flow ITA graft maintained its anatomical patency for a period of 3 years in patient l and l year in patient 2. As previously described [I, 2, 61 it is possible that stringlike and no-flow ITA grafts can enlarge and become functionally patent again when stenosis of the bypassed coronary artery is advanced in certain patients in whom technical problems of anastomosis including graft injury during dissection [5] can be ruled out. The ITA graft in situ is thought to have functioned as an operatively prepared collateral vessel.
References 1. Dincer B, Barner HB. The "occluded" internal mammary artery graft. Restoration of patency after apparent occlusion associated with progression of coronary disease. J Thorac Cardiovasc Surg 1983;85:318-20. 2. Aris A, Borras X, Ramio J. Patency of internal mammary artery grafts in no flow situations. J Thorac Cardiovasc Surg 1987;93: 624.
Ann Thorac Surg 1W2;53156-9
3. Bamer HB. Double internal mammary-coronary artery bypass. Arch Surg 1974;109:627-30. 4. JA. Internal mammary artery-coronary artery mt anastomosis. Influence of the branches on surgical result. J Thorac Cardiovasc Surg 1981;82:909-14. 5. Mills NL, Ochsner JL. Technique of internal mammary-tocoronary artery bypass. Ann Thorac Surg 1974;1723746. 6. Kitamura S, Seki T, Kawachi K, et al. Excellent patency and growth potential of internal mammary artery grafting in
CASE REPORT KITMURA ET AL NO-FLOW ANATOMICAL PATENCY OF ITA GRAW
159
pediatric coronary artery bypass surgery: new evidence for a live conduit. Circulation 1988;78(Suppl 1):129-39. 7. Bruschke AVG, Wijers TS, Kolster W, et al. The anatomic evolution of coronary artery disease demonstrated corenary arteriography in 256 nonoperated patients’ 1981;63:527-36. 8. Ishikawa H, Uwatoko M, Watabe S , et al. Analysis of the evolution of coronary artery disease. Jpn Circ J 1986;50:57586.
INVITED COMMENTARY This report further corroborates previous observations suggesting the physiologic potential of the internal thoracic artery to dilate and contract depending on demand. If corroborated, this should reduce the surgeon’s concern about using the internal thoracic artery grafts in competitive flow situations. Further, it should encourage angiographers to investigate the potential of this test for evaluating patients with a string sign before reoperation. It is conceivable that a substantial proportion of the patients with a string sign do not need to have the conduit replaced at the time of reoperation or may not need the reoperation at all. Such observations could have major
implications on the angiographic indications for and the planning and the execution of a reoperation. It is hoped that the angiographers will further evaluate the usefulness of this technique. Delos M . Cosgrove Ill, M D Department of Thoracic and Cardiovascular Surgery The Cleveland Clinic Foundation One Clinic Center 9500 Euclid Ave Cleveland, OH 441 95-5066