ASSESSMENT OF AORTOCORONARY BYPASS GRAFT PATENCY BY INTRA-ARTERIAL DIGITAL SUBTRACTION ANGIOGRAPHY COMPARED TO SELECTIVE GRAFT ANGIOGRAPHY

The value of digital subtraction angiography (DSA), in assessing aortocoronary bypass graft patency, was evaluated by studying 22 consecutive patients with 54 aortocoronary saphenous vein bypass grafts, who had postoperative angina pectoris. Each patient underwent selective graft angiography and non-gated DSA. The DSA consisted of a run of 15 to 20 frames, taken at 2.3 frames per second during injection of diluted contrast in the ascending aorta, performed after a test exposure was made. Thirty-two of the 54 grafts (59%) were patent. Thirty of the 32 grafts were seen to be patent by both selective graft angiography and DSA. In addition, a further two grafts were found to be patent on DSA, but were not able to be selectively catheterised and were not seen on the conventional aortogram. Selective graft angiography revealed four tight proximal graft stenoses, of which one only was seen on DSA; and poor distal run-off in five grafts, two of which showed up as late filling grafts on DSA. In summary, the accuracy of intra-arterial DSA in assessment of bypass graft patency was excellent. All grafts seen to be patent on selective graft angiography were also seen by DSA alone and in addition two grafts which could not be selectively catheterised were found to be patent. However, in patients with postoperative chest pain, selective graft angiography is probably required as non-gated intra-arterial DSA does not provide sufficient information to assess graft stenoses, distal flow and the native coronary vessels.     

Intraarterial digital subtraction angiography for evaluation of internal mammary artery graft in coronary bypass surgery

Digital subtraction angiography (DSA) was performed to evaluate graft patency in 60 patients who had undergone coronary artery bypass grafting with the internal mammary artery (IMA). Sixty IMA grafts with 62 distal anastomoses, and 84 saphenous vein grafts with 85 distal anastomoses were evaluated by intraarterial DSA with an image frequency of 4 frames/sec. A No. 4 Fr. angiography catheter was introduced percutaneously into the left brachial artery and contrast medium was injected both into the subclavian artery for opacification of the IMA grafts and into the ascending aorta for opacification of aortocoronary saphenous vein grafts. Bypass grafts were defined as patent when grafts were opacified through their entire course, including anastomotic sites. Fifty-nine IMA grafts with 61 distal anastomoses (98%) and 76 saphenous vein grafts with 77 distal anastomoses (91%) were patent. The overall patency rate for total grafts was 94%. In 4 patients, DSA showed a "string sign" in the IMA graft which was patent but narrowed at its distal segment. In 5 patients, large first intercostal branches were opacified. Intraarterial DSA with the retrograde brachial approach is not difficult, and is an excellent low risk method of evaluating the patency of IMA and saphenous vein grafts. DSA provided information about functional patency as well as anatomical patency of the IMA graft.     

Assessment of coronary bypass graft patency by electron-beam computed tomography

Twenty-one patients undergoing coronary artery bypass grafting were prospectively evaluated by conventional selective coronary angiography and electron-beam computed tomography. Eighty bypass grafts (60 saphenous vein and 20 left or right internal mammary artery) were evaluated for patency. The sensitivity and specificity of electron-beam computed tomography were 72% and 100%, respectively; positive and negative predictive values were 100% and 92.5%, respectively. Sensitivity and specificity according to coronary region were: left anterior descending artery, 33% and 100%; diagonal artery, 67% and 100%; circumflex artery, 75% and 100%; right coronary artery, 100% and 100%. Electron-beam computed tomography is relatively accurate and a promising tool for noninvasive evaluation of graft patency after coronary artery bypass graft surgery.     

Value of navigator echo magnetic resonance angiography in detecting occlusion/patency of arterial and venous, single and sequential coronary bypass grafts

Aim of our work was to validate magnetic resonance angiography (MRA) in detecting occlusion/patency of coronary artery bypass grafts. Twenty patients with previous history of bypass surgery and recurrent episodes of chest pain were enrolled. Two patients could not be studied (claustrophobia, erratic breathing). Thus, 18 patients with 51 bypasses were examined using a navigator echo sequence: 21 arterial grafts (six sequential) and 30 saphenous vein grafts (five sequential). All patients had undergone contrast conventional angiography 3–15 days before MRA. The magnetic resonance (MR) data set was analyzed by two independent readers blinded to the results of conventional angiography (occlusion of 12 of 51 grafts). At magnetic resonance, two bypasses of the posterior descending artery, patent at conventional angiography, could not be visualized because of imaging slab malpositioning. Interobserver concordance was 96% (47/49). Magnetic resonance and conventional angiography provided identical answers in 47 out of 49 (96%) of the examined grafts. Eleven out of 12 occluded grafts and 36 out of 37 patent grafts were correctly identified with MR. As far as occlusion is concerned, the sensitivity of MR was 91%, the specificity 97%. To summarize, a 30 min outpatient MR examination is highly reliable in determining occlusion/patency of arterial and venous, single and sequential bypasses.     

Prospective evaluation of ultrafast cardiac computed tomography for determination of coronary bypass graft patency

Twenty-five consecutive patients with 68 independent (single distal anastomosis) saphenous vein aortocoronary and 12 internal mammary bypass grafts (27 to left anterior descending, 10 to diagonal, 23 to left circumflex, 20 to right coronary artery) entered a reader-blinded, prospective, standardized study to establish the accuracy of ultrafast (cine) cardiac computed tomography (CT) for determining graft patency compared with invasive angiography. All patients underwent imaging after injection of 35 to 45 ml of meglumine diatrizoate (Renografin-76; 7 to 9 ml/sec for 5 sec) into an arm vein. Electrocardiographically triggered images were acquired over eight to 16 tomographic levels at 1 cm intervals from aortic arch to mid left ventricle. Criteria for graft patency were contrast opacification on at least two noncontinguous levels and contrast density-time curves morphologically similar to that of the aorta. Ultrafast CT correctly determined that 46 of 48 bypass grafts were patent and 31 of 32 were occluded (sensitivity, specificity, and accuracy 96%, 97%, and 96%); there were no interpretation errors in 23 (92%) of the 25 patients. Accuracy was independent of vessel bypassed and not different for saphenous veins (96%) compared with internal mammary bypasses (100%). This study establishes a 20 min outpatient intravenous injection technique that is highly accurate for determining patency of coronary artery bypass grafts.     

多排螺旋CT冠脉成像与冠脉造影对冠心病诊断的对比研究

目的初步评价多排螺旋CT（MSCT）在冠状动脉成像中的临床应用价值。方法18例疑诊冠状动脉狭窄患者行MSCT扫描,利用影像曲面重建,3D重建,了解冠状动脉病变情况,并与冠状动脉造影（CAG）对比。结果18例76支血管同时经MSCT和CAG成像。CAG发现狭窄27支,其中左前降支（LAD）病变11支,回旋支（LCA）病变3支,左主干（LMA）2支,右冠（RCA）病变9支,桥支病变2支。MSCT发现狭窄24支,其中LAD病变11支,LCA病变3支,LMA病变1支,RCA病变7支,桥支病变2支。MSCT与CAG结果相符的病变血管22支,MSCT成像的敏感性为82%（22/27）,特异性96%（47/49）。结论在控制心率的情况下MSCT可作为冠状动脉狭窄的一种无创筛选检查方法。     

Three-dimensional computed tomography angiography of coronary artery bypass graft with electron beam tomography]

OBJECTIVES: Assessment of coronary artery bypass graft patency by three-dimensional reconstructed computed tomography angiography (3D-CTA) derived from electrocardiography-gated contrast-enhanced electron beam tomography (EBT) was evaluated. METHODS: Thirty-nine patients with 99 grafts (45 arterial grafts and 54 venous grafts) underwent 3D-CTA and selective coronary angiography within a 3-week interval. 3D-CTA images of the coronary bypass grafts were compared with the coronary angiography images used as the control. RESULTS: 3D-CTA defined 42 of 44 arterial grafts as patent (sensitivity: 95%), all 47 venous grafts as patent (sensitivity: 100%) and all 7 venous grafts as occlusive (specificity: 100%). The overall sensitivity and specificity were 98% and 88%, respectively. CONCLUSIONS: 3D-CTA is an useful noninvasive technique with adequate sensitivity and specificity to assess coronary artery bypass graft patency.     

Electrocardiographic changes during selective aortocoronary saphenous vein bypass graft angiography in man

Simultaneous leads I, II, and III of the electrocardiogram were recorded during selective aortocoronary saphenous vein bypass graft angiography in 20 patients. Arrhythmias associated with such graft opacification included sinus bradycardia, sinus arrest, atrial premature beats, ventricular premature beats, ventricular tachycardia and two episodes of ventricular fibrillation. Rhythm disturbances were unrelated to the anatomic location of the grafts. Patent right graft injection effected a mean rightward frontal plane QRS axis shift of 32.7 ° with leftward T wave axis deviation. A majority of subjects with patent aortic-left anterior descending coronary arterial grafts also manifested right axis shift (mean 22.6 °), possibly related to collateral circulation between the left and right coronary arterial systems. Those patients with stenosed and occluded grafts had minimal or no electrocardiographic changes during bypass angiography. It is concluded that electrocardiographic alteration during graft angiography is a physiologic demonstration of aortocoronary bypass efficacy.     

Routine intraoperative angiography improves the early patency of coronary grafts performed on the beating heart

OBJECTIVES: The techniques of performing coronary revascularization without cardiopulmonary bypass are rapidly evolving. However, concern remains regarding the accuracy of coronary artery anastomoses performed on the beating heart. This report reviews the use of intraoperative angiography in the critical appraisal of "off-pump" coronary artery bypass graft (CABG) surgery. PATIENTS: Intraoperative angiography was performed in 24 consecutive patients undergoing CABG surgery without cardiopulmonary bypass. In all, 24 left internal mammary artery (LIMA) grafts and 18 saphenous vein bypass grafts were assessed for patency, anastomosis quality, distal and proximal runoff, and correct placement. RESULTS: All of the saphenous vein-to-coronary artery anastomoses were widely patent, although two patients (8%) required revision of their LIMA grafts on the basis of angiographic findings. CONCLUSION: Intraoperative angiography permits the surgeon to immediately appraise the CABG and to revise, if necessary, any graft abnormality, thus potentially eliminating the need for early repeated surgery. The practice of routine intraoperative angiography is likely to improve the outcome of CABG surgery on the beating heart.     

Dysfunction of aortocoronary bypass. Prognosis]

From 1978 to 1988, 108 patients with at least one occluded or stenosed aorto-coronary bypass graft (over 75% stenosis) underwent coronary angiography on average 31 months after the initial coronary bypass surgery. The occluded or stenosed coronary graft was either a saphenous vein (n = 126 including 9 sequentials) or internal mammary artery (n = 5). The bypassed artery was the left anterior descending (n = 66), right coronary (n = 40), left marginal (n = 25) or diagonal (n = 9). The number of occluded or stenosed grafts by patient was 1.2. The left ventricular ejection fraction was 55% (range 25 to 77%). During a mean follow-up period of 60 months after coronary angiography, there were 14 cardiac deaths and 15 non-lethal myocardial infarctions. Treatment comprised 12 angioplasties, 26 new bypass grafts and 3 cardiac transplantations. The 8 year actuarial survival was 84%. The survival without infarction at 8 years was 69%. Survival was significantly decreased to 72% when the occluded or stenosed graft was located on the left anterior descending artery. The survival without infarction at 8 years was 52% in the patients with dysfunction of left anterior descending artery grafts and 89% when the diseased graft was located on another artery (right coronary, left marginal, diagonal). Therefore, the data of this retrospective study show that coronary graft dysfunction on the right coronary, left marginal or diagonal arteries do not greatly influence life expectancy in the medium term after coronary bypass surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

16排CT对冠状动脉桥血管病变评估的临床应用价值

目的探讨16排计算机断层扫描技术对冠状动脉桥血管病变评估的临床应用价值。方法本研究共入选62例冠状动脉旁路移植术后患者,其中6例因心率控制不佳被排除。对其余56例共152条桥血管(其中内乳动脉桥48条,隐静脉桥104条)分别用16排CT造影(CTA)和常规冠状动脉造影(CAG)进行检查。CTA检查均通过回顾性心电图门控方法进行。患者平均心率(58±6)次/min。在CTA检查过程中以4ml/s速度静脉注入120ml的Visipaque320造影剂。冠状动脉桥血管的通畅和狭窄程度由两位有经验的医师来评估。结果在本研究中,CTA方法能显示所有冠状动脉桥血管;CTA还能显示所有桥血管近端吻合处以及71%的远端吻合处。并且,经CTA检查发现有29条桥血管发生闭塞,13条桥血管有显著狭窄病变。通过CAG检查比较CTA结果证实:在所有42条CTA检查发现闭塞或狭窄的冠状动脉桥血管中,CAG显示有34条桥血管有闭塞或狭窄;在所有110条CTA检查显示正常的冠状动脉桥血管中,CAG显示有108条桥血管正常,有8例假阳性和2例假阴性发生。CTA检查的敏感性94%,特异性95%;阳性预测值86%,阴性预测值99%。结论CTA可提供清晰的冠状动脉桥血管图像以及较高的诊断准确性。CTA可作为评估冠状动脉桥血管病变的一种无创检查方法。     

Complete proximal occlusion of all three main coronary arteries complicated with a left main coronary aneurysm: a case report

A 68-year-old woman with recurrent chest pain was referred to our institution. Coronary angiography showed 100% obstruction of the left main trunk, the proximal right coronary artery with good collaterals to the left anterior descending artery and left circumflex artery along the conus artery. Emergency surgical revascularization was undertaken with two saphenous vein grafts. The saphenous vein grafts were placed in the left anterior descending artery, obtuse marginal branch and the posterolateral and posterior descending coronary arteries with excellent flow. The postoperative course was uneventful and follow-up angiography was obtained 20 days after the surgery. Coronary angiography demonstrated a saccular aneurysm (10 x 9 mm) originating at the distal segment of the left main coronary artery with 90% stenosis, and excellent patency of both saphenous vein grafts. Follow-up angiography was performed 1 and 3 years after the surgery. The size of the left main coronary aneurysm remained unchanged at both examinations. The patient did well with no further cardiac symptoms after 5 years.     

Direct non-invasive techniques for assessing coronary bypass graft patency

Summary Venous digital subtraction angiography (vDSA) and computed tomography (CT) are two non-invasive techniques that allow direct imaging of coronary grafts. Neither of them is 100% accurate when compared to selective angiography.We studied 52 patients with 107 coronary grafts (101 saphenous and 6 mammary artery grafts) by CT and vDSA. Fifty patients had control selective angiography and 2 had control digital arterial aortography. CT correctly diagnosed 88 of the 95 patent grafts and 8 out of the 12 occluded grafts (in 1 patient 3 patent grafts could not be well analyzed owing to artifacts from pacemaker wires). vDSA correctly identified 93 patent grafts and the 12 occluded grafts, allowing the correct diagnosis of the 11 non/or misdiagnosed CT grafts. CT allowed the correct identification of ihe 2 misdiagnosed vDSA grafts.These results show that when there was agreement between CT and vDSA there were no diagnostic errors and that the combination of these two non-invasive techniques may avoid selective angiography for studying coronary bypass graft patency.     

Noninvasive detection of coronary artery bypass graft patency by intravenous electron beam computed tomographic angiography

This study evaluates the usefullness of intravenous electron beam computed tomographic angiography (EBA) for the detection of coronary artery bypass graft patency in 43 patients (33 men and 10 women, mean age, 65 years) who had coronary artery bypass graft surgery. EBA was performed a few days before selective bypass graft angiography (SGA). Forty axial cross-sections of angiographic images of the heart were acquired consecutively by an electrocardiographic trigger signal at 40% of the RR interval, which corresponds to the end-systolic phase. EBA data were reconstructed as a three-dimensional shaded surface display of the heart and bypass grafts. Detectability of the patency of bypass gratis was evaluated, taking selective angiographic images of the bypass grafts as a gold standard. One hundred and nine grafts (96%) out of 114 grafts were subjected to evaluation: 37 grafts were left internal mammary artery grafts (LIMA), 7 were right internal mammary artery grafts (RIMA), 6 were gastroepiploic artery grafts (GEA), 7 were free gastroepiploic artery grafts with venous drainage (free-GEA), 7 were radial artery grafts (RAG), and 45 were saphenous vein gratis (SVG). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EBA were 98%, 100%, 100%, 91%, and 98%, respectively. EBA sampled at the end-systolic period was determined to be useful for the detection of coronary artery bypass graft patency and occlusion.     

Early postoperative occlusion of a left internal mammary artery bypass graft with subsequent restoration of patency.

Total occlusion of a left internal mammary artery (LIMA) bypass graft is a rare complication, and reversal of a documented occlusion has not been reported. This is a case of an early postoperative occlusion of a LIMA graft that was found to be patent 4 months later. A patient with three vessel disease (including a moderate lesion in the proximal left anterior descending artery and a severe lesion in its mid-portion) underwent coronary artery bypass grafting with a LIMA to the mid-left anterior descending artery (LAD) and saphenous vein grafts to the right coronary and left circumflex arteries. Coronary angiography 3 months after surgery revealed a totally occluded internal mammary artery and saphenous vein grafts. The patient then underwent a successful angioplasty of the more distal lesion in the LAD. She subsequently returned with recurrent angina. Repeat coronary angiography revealed rapid progression of the disease in the proximal LAD with the more distal angioplasty site being widely patent. Selective arteriography of the internal mammary artery at that time revealed a patent vessel. Thus, the internal mammary graft is a physiologically active conduit that is dependent on flow dynamics. Competitive flow through the nonobstructive native LAD in combination with impedance of flow through the internal mammary artery due to a severe lesion in the LAD distal to the anastomosis led to a functionally occluded LIMA. When the obstruction in the proximal LAD progressed and the distal obstruction was successfully angioplastied, the flow dynamics in the internal mammary improved, allowing for its dilatation and restoration of patency.(ABSTRACT TRUNCATED AT 250 WORDS)     

Atherosclerosis after coronary artery bypass surgery: results of recent studies and recommendations regarding prevention

Atherosclerosis is the most frequent cause of occlusion of aortocoronary saphenous vein grafts between 5 and 10 years after coronary artery bypass surgery. The typical atherosclerotic plaque appears between 1 and 3 years after operation and, at a mean of 5 years, histologic changes of atherosclerosis are present in 21% of grafts and in 27% of patients. Only approximately 60% of saphenous vein grafts remain patent at repeat angiography between 10 and 12 years after bypass surgery; 45% of patent grafts show atherosclerotic changes at angiography and 43% of patients show evidence of atherosclerosis in one or more saphenous vein grafts. We do not know whether the development or the progression of these atherosclerotic changes can be modified; however, the data currently available suggest that the administration of platelet inhibitors and/or of lipid lowering agents offer two promising avenues of investigation in patients undergoing aortocoronary saphenous vein bypass surgery. Until this has been carefully studied, the internal mammary artery should remain the preferred conduit for aortocoronary bypass grafting, whenever possible.     

Intravascular echocardiography (ICUS) diagnosis of post-traumatic coronary dissection involving the common trunk. A case report and review of the literature]

A case is reported in which a 31-years-old man experienced coronary artery dissection with an acute anterior myocardial infarction following blunt chest trauma in a car accident. Due to ECG signs of acute myocardial infarction a coronary angiography was performed showing an abrupt occlusion of the mid part of the left anterior descending artery and a linear filling defect in the proximal portion of the vessel. Additional detailed intravascular ultrasound was performed, revealing a long intimal tear involving the left anterior descending artery and the left main. The patient underwent immediate coronary artery bypass surgery. Two vein grafts were made from aorta to the left anterior descending artery and the circumflex artery, respectively. Repeat angiography was performed early after the operation; dissection of the left main and the left anterior descending artery was still visible and the grafts to the left descending artery and the circumflex were patent.     

Are metallic markers necessary for coronary artery bypass grafts? A study using X-ray computed tomography and selective graft angiography

Using X-ray computed tomography (CT) and selective graft angiography, the authors studied the necessity of metallic markers in coronary artery bypass grafts on 45 patients (mean age 57.2 years) with 87 saphenous vein grafts. Eight patients had 17 markers. X-ray CT was performed after surgery using an apparatus with a 1-second scanning time. Noncontrast X-ray CT was performed on horizontal sections, at 5-mm intervals, from the lower margin of the aortic arch to the lower left ventricle. A contrast medium was then injected into the antecubital vein (3 ml/second, total 30 ml) in one cross-section at the level of bifurcation of the pulmonary artery. Aortography (60° in the left anterior and oblique positions, 20 ml/second, total 40 ml) was performed concurrently. Selective graft angiography was taken in the same direction, using 4 cm right of the Judkins with reference to the aortographic image and position of five clips on the sternum. Aortography revealed 79 patent and 8 occluded grafts. Selective graft angiography was easily performed even in grafts without markers. A cross-section of the occulded graft could not be seen with X-ray CT. Grafts with markers were often masked by artifacts produced by markers on X-ray CT. The number of observed graft slices (marker-positive grafts) was only 1.2±1.1 slices, significantly (p<0.01) lower than marker-negative grafts (4.1±3.1 slices). In particular, the number of marker-positive right coronary artery grafts was 0.4±0.9 slices. Four of five right coronary artery grafts were unobservable due to artifacts. In grafts without markers, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of X-ray CT to graft patency were 100%, 85.7%, 98.4%, 100%, and 98.6%, respectively. This study suggests that metallic markers may not be necessary for coronary artery bypass grafts.A working version of this report was presented at the 39th Annual Congress of the International College of Angiology, Istanbul, Turkey, June 1997     

Follow-up angiography of 100 revascularizations of the anterior interventricular artery by the left internal mammary artery

One hundred and fifty patients who underwent revascularisation of the left anterior descending artery (LAD) by the left internal mammary artery (LIMA) between 1981 and 1983 were recalled for control coronary angiography one year after surgery. One hundred patients gave consent. The patency rate in these 100 patients was 90 per cent. The presumed causes of the 10 thromboses observed were: for LAD (5 cases), technical problems (3 cases), competitive flow (2 cases). Ten per cent of the patent LIMA grafts were abnormal: moderate stenosis of the anastomosis (5 cases), small LIMA (3 cases), stenosis of the middle segment of the LIMA (1 case). In addition, we observed 7 cases of competitive flows: 3 cases with a LAD which was not sufficiently stenotic, 4 cases with a large saphenous diagonal bypass graft. If a diagonal artery bypass is necessary, it is better to revascularize by either a latero-lateral anastomosis with the LIMA or by using the right IMA. Ninety per cent of the patent grafts were quite satisfactory ar 1 year: regular, supple, and perfectly congruent with the bypassed artery which was injected massively. As a number of North American teams have shown, this good patency rate seems to be maintained at long term, which is not the case with saphenous vein bypass grafts.     

Value of transverse radiotomography in the control of the permeability of aortocoronary bypasses, compared with coronary angiography

The object of this study was to determine whether transverse radiotomography, despite cardiac movement, could be used to visualise aortocoronary bypass grafts to confirm their patency or obstruction. The results were then compared with those of coronary angiography. 20 patients with a total of 38 grafts (18 on the left anterior descending, 8 on the circumflex and 12 on the right coronary artery) underwent tomography. 1 or 2 60 ml boluses of iodide contrast medium were injected into a fore arm vein and 3-5 films were exposed after each injection at 15 sec intervals. Coronary angiography was performed in 16 patients and the results of tomography were identical to those of coronary angiography : 23 patent and 6 occluded grafts. In one case, subtotal proximal stenosis of the left anterior descending artery allowed sufficient flow for the graft to be opacified and considered patent on tomography. The correlation between transverse radiotomography and coronary angiography was excellent. Transverse radiotomography, a non-invasive technique, is very useful in operated patients with atypical chest pain and in those with recurrent angina in whom obstruction of the graft is feared. It does not seem destined to replace control coronary angiography after bypass surgery, but it may be indicated is selected cases.