Effect of target stenosis and location on radial artery graft patency.

OBJECTIVE: The purpose of this study was to evaluate the effect of target vessel characteristics on radial artery patency when used as a composite T graft. METHODS: Between October 1993 and March 2001, 1022 patients underwent coronary bypass with the internal thoracic artery-radial artery composite T graft. Of these, angiography has been performed on 109 patients at a mean 27.1 months (range, 2-70 months) postoperatively for symptoms of ischemia. By means of Cox proportional hazard models, the relationships between anastomotic patency and target vessel location, proximal stenosis, target diameter, and quality were assessed. RESULTS: A total of 231 radial artery anastomoses were evaluated. The mean stenosis for patent anastomoses was 82% compared with 71% for occluded anastomoses (P <.001). Anastomotic patency for targets with moderate stenosis (< or = 70%) was worse than that for vessels with critical stenosis (> or = 90%; relative risk, 1.7; 95% confidence interval, 1.3-2.2; P <.001). Patency for targets of the right coronary artery was statistically inferior to that for targets of the left anterior descending artery (relative risk, 1.8; 95% confidence interval, 1.2-2.9; P =.01) and bordered on significance versus that for the circumflex artery distribution (relative risk, 1.6; 95% confidence interval, 1.0-2.8; P =.06). When directed toward critically stenosed targets of the left anterior descending or circumflex arteries, radial artery patency was not statistically different that that of the internal thoracic artery (P =.19). CONCLUSION: Radial artery patency is sensitive to both target location and proximal target stenosis. Selective use of the radial artery to targets of the left anterior descending and circumflex distributions remains encouraging. Radial artery grafts to targets of the right coronary artery or those with moderate stenosis appear to be at particularly high risk of failure.     

Effect of coronary artery bypass grafting on native coronary artery stenosis. Comparison of internal thoracic artery and saphenous vein grafts

BACKGROUND: The purpose of this study was to investigate the influence of coronary artery bypass grafting on the degree of stenosis of the native coronary artery. METHODS: Experimental design: retrospective data analysis. Setting: University hospital. Patients: consecutive patients undergoing coronary artery bypass grafting (n=52). Bypasses using internal thoracic artery grafts (n=26) and saphenous vein grafts (n=37) to incompletely occluded coronary arteries were studied. Interventions: coronary artery bypass grafting using internal thoracic artery or saphenous vein grafts. Measures: stenosis of the native coronary artery on angiography. RESULTS: Three recipient coronary arteries bypassed with internal thoracic artery grafts (12%) and 14 recipient coronary arteries bypassed with saphenous vein grafts (38%) showed progression of narrowing (p=0.024). Two recipient coronary arteries bypassed with internal thoracic artery grafts (8%) and 13 recipient coronary arteries bypassed with saphenous vein grafts (35%) showed total occlusion (p=0.016). Hypertension, hyperlipidemia, diabetes mellitus, and smoking history did not correlate with progression of stenosis of the native coronary arteries. Graft flow measured during surgery in the saphenous vein grafts was not significantly different between the group that exhibited progression of the native stenosis and the group that did not. CONCLUSIONS: Coronary artery bypass grafting with saphenous vein grafts may result in progression of stenosis of the recipient coronary artery. This is less likely after coronary artery bypass grafting with internal thoracic artery grafts. This difference may be due to the ability of the pedicled internal thoracic artery graft to regulate flow. Thus competitive flow in the native coronary artery is minimized. This has significant clinical implications.     

T grafts with the right internal thoracic artery to left internal thoracic artery versus the left internal thoracic artery and radial artery: flow dynamics in the internal thoracic artery main stem.

OBJECTIVE: Complete arterial coronary artery bypass grafting with 2 grafts can be achieved even in triple vessel disease by use of a T configuration. There is still uncertainty whether the coronary flow reserve in the main stem of the left internal thoracic artery is sufficient to supply more than 1 anastomosed coronary vessel. METHODS: Between March 1996 and February 1999, 251 patients with multivessel coronary artery disease underwent complete arterial revascularization with T grafts, using either the left internal thoracic artery with the free right internal thoracic artery graft (n = 73, group I) or the left internal thoracic artery and radial artery (n = 178, group II). A mean of 4.0 (group I) versus 4.3 (group II) coronary vessels were anastomosed per patient. One week (n = 92) and 6 months (n = 28) after the operation, flow was measured in the proximal left internal thoracic artery with a Doppler guide wire. Maximum flow was determined after injection of adenosine (30 microg). RESULTS: The in-hospital mortality was 2.7% (group I) versus 2.3% (group II). At angiography (n = 142, 56.6%) the patency rate was 96.3% (group I) versus 98.2% (group II). There was no significant difference between baseline flow, maximum flow, and coronary flow reserve between the 2 groups. Coronary flow reserve increased in both groups within the first 6 postoperative months (group I, 1.85 +/- 0.31 vs 2.77 +/- 0.77, P =.0002; group II, 1.82 +/- 0.4 vs 2.53 +/- 0.73, P =.009). CONCLUSION: Both variants of T grafts allow for complete arterial revascularization with good perioperative results. The flow reserve of the proximal internal thoracic artery is adequate for multiple coronary anastomoses irrespective of the choice of the second arterial graft.     

Failure of internal thoracic artery grafts: conclusions from coronary angiography mid-term follow-up

BACKGROUND: The objective of this study was to identify causes of the failures of internal thoracic artery bypass grafts according to operative technique, the internal thoracic artery used, and the coronary artery grafted. METHODS: This retrospective study concerns 302 follow-up angiographies performed in patients treated with 512 internal thoracic artery bypass grafts: 115 single grafts, 78 sequential grafts, and 109 grafts with two internal thoracic arteries (61 Y grafts). Postoperative angiography was performed after a mean period of 17.3 +/- 4.1 months. RESULTS: Failures consisted of 11 (2%) occluded grafts and 19 (4%) nonfunctioning grafts (threadlike internal thoracic artery). There was no difference in patency among the various types of left anterior descending artery bypass grafts anastomosed with the left internal thoracic artery. The failure rate was higher with the right internal thoracic artery (13%) than with the left internal thoracic artery (4%; p < 0.05). The failure rate of the left anterior descending artery bypass grafts (3%) was lower than that for the branches of circumflex artery bypass grafts (13%; p < 0.05). The 19 cases of nonfunctioning grafts did not include significant anastomotic stenosis: 14 were related to competitive blood flow, 4 to a poor recipient coronary arterial bed, and 1 to significant distal coronary stenosis. CONCLUSIONS: At least two thirds of failures of bypass grafts could have been avoided by more objective analysis of the coronary stenosis on preoperative coronary angiography and better mastery of the surgical technique.     

Revascularization with bilateral internal thoracic artery grafts in patients with left main coronary stenosis.

Left main occlusive disease (LMD) is a potentially fatal lesion which is optimally treated with surgical revascularization. Although the internal thoracic artery (ITA) is recognized as having superior long term patency, there has been concern regarding possible flow limitation. Because of this concern, there may be reluctance to use only this conduit in patients with LMD in whom high graft flows are desirable. From 1985 to 1990, 45 patients (38 males, 7 females) with LMD ranging in age from 37 to 75 years (mean 55.9 +/- 8.7) underwent revascularization using bilateral ITA grafts placed to the left anterior descending and circumflex arteries. The right ITA was used as a free graft in 19 of 45 (42%) patients and the left ITA was used as a free graft in 3 of 35 (7%). No saphenous vein grafts were placed to the left coronary system in any patient. Over half of these patients (24 patients, 53%) also had occlusive disease in the right coronary artery. A saphenous vein graft was placed to the right coronary artery in 22 of 45 (49%) patients. Ventricular function in this patient subset was good (mean LV score 7.1 +/- 2.1). Intra-operative ITA graft flows were 49.7 +/- 29.1 ml/min for grafts to the left anterior descending and 45.5 +/- 31.7 ml/min for circumflex grafts. There were no perioperative deaths. Morbidity included myocardial infarction, stroke and reoperation for bleeding in 1 patient each (2.2%). Low cardiac output occurred in 2 patients (4.4%). No patient had a mediastinal wound infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vasoreactivity of arterial grafts in the patient with diabetes mellitus: investigations on internal thoracic artery and radial artery conduits.

OBJECTIVE: Arterial revascularization with either internal thoracic artery (ITA) or radial artery (RA) appears to be particularly attractive in diabetic patients. Previous investigations have shown that endothelial dysfunction and artherosclerosis are seen more often in these patients. The aim of this study was to compare the vasoreactive properties of ITA and RA grafts in diabetic and non-diabetic patients. METHODS: Arterial rings were harvested from 57 patients who underwent complete arterial revascularization. The patients were divided into a non-diabetic group (I: n = 30) and patients with diabetes mellitus (II: n = 27). Arterial rings of the ITA (I: n = 30; II: n = 27) and RA (I: n = 28; II: n = 19) were mounted on a strain gauge in oxygenated, normothermic Krebs's--Henseleit solution at optimal resting tension. With KCL (80 mM) serving as the control, assessment of force of contraction (norepinephrine), endothelium-dependent relaxation (acetylcholine) and smooth muscle-dependent relaxation (glyceroltrinitrate) were obtained. RESULTS: After KCL, the RA showed a trend to lower maximum contraction forces in diabetics (I: 76 +/- 25 mN; II: 69 +/- 29 mN), which was pronounced in patients with diabetes of more than 10 years duration (55 +/- 23 mN; P = 0.1). Maximum contraction force of the ITA was similar in both groups (I: 41 +/- 20 mN; II: 34 +/- 19 mN) and not influenced by the duration of diabetes. The two groups showed no significant differences of the relative vasoconstriction after norepinephrine in RA (I: 53 +/- 18%; II: 61 +/- 19%) and ITA rings (I: 70 +/- 23%; II: 69 +/- 25%). Also, endothelium-dependent relaxation with acetylcholine in RA (I: 53 +/- 14%; II: 57 +/- 16%) and ITA rings (I: 42 +/- 17%; II: 44 +/- 20%), and smooth muscle relaxation with glyceroltrinitrate of RA (I: 72 +/- 8%; II: 73 +/- 12%) and ITA rings (I: 64 +/- 12%; II: 58 +/- 20%) was comparable in both groups. No influence of duration of the diabetic disease was noted. CONCLUSIONS: Although RA rings of patients with a long duration of diabetes have decreased maximum contraction forces, their relative vasoconstriction after norepinephrine, endothelium-dependent relaxation and smooth muscle relaxation was similar to non-diabetic patients. We thus conclude that the RA is an adequate arterial conduit in the patient with diabetes mellitus.     

Does Doppler echography have a diagnostic role in patency assessment of internal thoracic artery grafts?

The amount of literature published over the past decade comparing coronary angiography with transthoracic Doppler echocardiography assessment of internal thoracic artery graft patency after CABG is substantial. There has been no review of the available literature, and conflicting reports of diagnostic accuracy have prevented routine use of transthoracic Doppler in graft patency assessment. Thus, this article reviews the available literature on diagnostic accuracy of transthoracic Doppler echocardiography of coronary bypass grafts. Relevant studies were identified and meta-analysis of diagnostic accuracy was performed. Study quality was assessed. Quantitative data synthesis included calculation of sensitivity, specificity, summary receiver operating characteristic curve analysis, pooled analysis and meta-regression of accuracy against study quality, publication date, angina, probe frequency and diagnostic criteria. Twenty studies of 929 patients produced 26 results included for analysis. Grafts were not visualized in 93 (10%) patients. Pooled sensitivity (85%) and specificity (94%) and diagnostic odds ratio (100.7) were high. SROC analysis showed an area under the curve of 0.96. Heterogeneity of results was due to variations in diagnostic criteria and study size. Subgroup analysis showed best performance in patients with postoperative angina (p = 0.014). Study quality did not affect results. Diastolic fraction less than 0.5 (sensitivity 89%, specificity 94%) was shown to be the best criterion for prediction of stenosis. Performance was lower using peak diastolic to systolic velocity ratio less than 1 (sensitivity 85%, specificity 86%). Transthoracic Doppler echography is effective in first-line assessment of left internal thoracic artery graft patency. It shows high specificity, prevents invasive investigations and improves in patients with postoperative angina. TDE is best used in combination with other non-invasive tests due to its inability to visualize the graft. The potential for use in postoperative coronary bypass patients is high.     

Skeletonized harvesting improves the early-term and mid-term perfect patency of a radial artery graft

Objective A radial artery (RA) graft is frequently used for coronary artery bypass grafting (CABG), but little information exists regarding the early- and mid-term patency associated with the harvesting procedure. The objective of this study is to compare the early- and midterm patency of the RA graft obtained using non-skeletonized and skeletonized harvesting. Methods Altogether, 131 patients and 159 anastomoses were studied. In 85 patients the RA was harvested non-skeletonized (group A: procedures between September 2000 and November 2002), whereas in 46 patients the RA was harvested skeletonized (group B: procedures between November 2002 and April 2004). Angiography results were analyzed before discharge [A: postoperative day (POD) 14.7 ± 2.9, 75 patients, 90 anastomoses; B: POD 13.7 ± 1.9, 38 patients, 47 anastomoses], and after 1 year (A: POD 386.8 ± 149.3, 44 patients, 51 anastomoses; B: POD 267.1 ± 148.7, 11 patients, 13 anastomoses). Results There was no difference in patency between the two groups (group A vs group B, 96.7% vs 100%, P = not significant [NS], in the early-term, 96.2% vs 100%, P = NS, in the mid-term). However, the perfect patency rates for groups A and B were 86.7% and 98.1%, respectively, in the early-term (P = 0.034) and 77.5% and 100%, respectively, in the mid-term (P = 0.048). The location and severity of the target vessel did not influence the angiographic results. Conclusion The early- and mid-term patency of RA grafts was excellent, and skeletonized harvesting improved the perfect patency rates at both time points.     

Myocardial revascularization with multiple arterial grafts: comparison between the radial artery and the right internal thoracic artery

Background. Bilateral internal thoracic artery (ITA) harvesting is significantly underused, whereas the radial artery is being used with increasing frequency. We have retrospectively analyzed perioperative and short-term outcomes of patients receiving a radial artery versus those receiving a right ITA as a second arterial graft.

Methods. Between February 1999 and May 2000, 250 patients underwent coronary artery bypass grafting using the radial artery (156 patients) or the right ITA (94 patients) in combination with the left ITA and, when required, the saphenous vein.

Results. There was a higher prevalence of risk factors in the radial artery group. More coronary artery bypass graftings (p < 0.001) were performed with the radial artery. Operative mortality was not different (p = not significant). In the right ITA group there was more bleeding (p < 0.001) and a longer hospital stay (p < 0.001). Mean follow-up was 8.1 ± 3.9 months. The probability of survival was similar (p = not significant).

Conclusions. The radial artery can extend the benefits of multiple arterial grafting to those patients who are usually excluded from bilateral ITA harvesting because of multiple risk factors. Perioperative and short-term results are good.     

Angiographic demonstration of no-flow anatomical patency of internal thoracic-coronary artery bypass grafts.

To clarify the no-flow situation of the stringlike internal thoracic artery graft, we angiographically examined 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 1 year and 3 years after the operations. Thus, there is a possibility that internal thoracic artery grafts may continuously maintain anatomical patency even under no-flow situations just like nonfunctioning collateral 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.     

Free flow capacity of skeletonized versus pedicled internal thoracic artery grafts in coronary artery bypass grafts.

OBJECTIVE: The internal thoracic artery (ITA) is the ideal conduit for coronary artery bypass grafting (CABG). The skeletonization technique of this arterial conduit has been proposed to reduce chest wall trauma, increase graft length and facilitate construction of sequential anastomoses. Nevertheless, some surgeons decline this technique because of potentially increased trauma to the ITA with impairment of flow. In this investigation we compared the free flow of skeletonized with that of pedicled ITA grafts. METHODS: Two surgeons operated on 80 consecutive patients with coronary artery disease for elective CABG. In group I (n = 40), the left ITA was dissected using the skeletonization technique. In group II (n = 40), it was harvested as a pedicled graft. In 23 patients of group I both ITA's were dissected in skeletonized fashion for complete arterial revascularization. Diluted papaverine was instilled into the lumen of the ITA after distal transection of the vessel in both groups. Free flow of the ITA was registered before and 15 min after intraluminal application of diluted papaverine. Mean arterial pressure was maintained at 70 mmHg. RESULTS: Before the application of papaverine, free flow of skeletonized and pedicled ITA grafts was identical between the two groups. After treatment with papaverine maximum free flow was significantly higher in the skeletonized ITA's (group I 197.2 (+/-66.6) ml/min; group II 147.1 (+/-70.5) ml/min; P < 0.05). There was no significant difference between free flow after dilatation of the left and right ITA in group I (left 197.2 (+/-66.6) ml/min; right 198.9 (+/-61.8) ml/min). CONCLUSIONS: Preparation of the ITA with the skeletonization technique results in significantly, higher free flow capacity than in pedicled grafts. This may increase the safety of arterial revascularization by reducing the risk of ITA hypoperfusion syndrome.     

Early and mid-term results of all arterial graft coronary artery bypass grafting using bilateral internal thoracic and radial arterial conduits

From March 1996 to May 2000, 41 patients [age 39-78 (mean 63.5 +/- 8.8) years, 90.2% male] underwent all arterial multiple coronary artery bypass grafting (CABG) using bilateral internal thoracic (BiITA) and radial (RA) arterial conduits. The reason for using RA was that the right gastroepiploic artery (RGEA) was small or occluded on preoperative angiography, a history of upper abdominal surgery or disease, or the right coronary arterial lesion was proximal and mild. The BiITA were used as in situ grafts and the proximal anastomosis of RA was to the ascending aorta in all cases. All patients underwent conventional elective CABG with median sternotomy using cardiopulmonary bypass. The mean number of anastomoses was 3.3 +/- 0.5 branches and complete revascularization rate was 80.5%. Postoperative follow-up averaged 20 months and the longest was 50 months. There was no early death, and overall graft patency 2-3 weeks after surgery was 96.2% (LITA 94.0%, RITA 97.6%, RA 97.6%). Four-year actuarial survival rate was 96.4 +/- 3.5% (1 patient: 9 months, no cardiac death), and cardiac event-free rate after surgery was 89.7 +/- 4.9% [4 patients: percutaneous transluminal coronary angioplasty (PTCA)]. However, once patients were discharged from hospital, cardiac event-free rate was 100%. These excellent results suggest that all arterial graft CABG was satisfactory, and RA can be used as a third suitable arterial bypass conduit, if RGEA cannot be used or is unsuitable for use.     

Carbon monoxide induces relaxation of human internal thoracic and radial arterial grafts

Carbon monoxide is produced by the degradation of heme by intracellular heme-oxygenase. The aim of our study was to evaluate, in vitro, the vasodilating effect of carbon monoxide and its mechanisms of action on human internal thoracic and radial artery grafts. Segments of human internal thoracic artery and radial artery, obtained from isolated coronary artery bypass surgery patients, were studied in organ chambers. The arterial rings were precontracted with norepinephrine then submitted to carbon monoxide. Inhibitors of nitric oxide synthase and of soluble guanylate cyclase were added to some arterial rings. Carbon monoxide induced significant relaxation in precontracted human internal thoracic artery and radial artery rings. This relaxation was independent of the presence of functional endothelium in internal thoracic artery. Blocking soluble guanylate cyclase partially inhibited this relaxation, while blocking nitric oxide synthase had no effect. Carbon monoxide has a relaxing effect on human internal thoracic artery and radial artery grafts in vitro, partially via cyclic guanylate monophosphate (cGMP) pathway activation. Inducing carbon monoxide production at the cellular level in vivo in human arterial grafts might help prevent vasospasm.