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Patency of internal thoracic artery grafts: comparison of right versus left and importance of vessel grafted.

BACKGROUND: The early and late patency of the left internal thoracic artery (LITA) has been studied thoroughly, but less is known about coronary artery bypass grafts constructed from the right internal thoracic artery (RITA). METHODS AND RESULTS: Between January 1984 and March 1991, 413 patients on two surgical services had bilateral arteries or RITAs used as conduits for coronary artery revascularization. Sixty-seven patients (16%; 57 male and 10 female; mean age, 59 years) had graft angiography performed up to 97 months after operation (average, 27 months). In 38 patients, angiography was performed because of angina or other objective evidence of myocardial ischemia. For all 67 patients evaluated, patency of RITA grafts was 86% (58/67), and patency of LITA grafts was 89% (57/64). For grafts to the left anterior descending (LAD) coronary artery, overall patency was 90% (58/64), and there was little difference in patency of the RITA (93%, 28/30) versus the LITA (88%, 30/34). In contrast, the overall patency rate for internal thoracic arteries used to bypass vessels other than the LAD was 76% (45/59, P < .03 versus LAD); for these bypasses to arteries other than the LAD, RITA patency was 74% (26/35), and the patency of LITA grafts was 79% (19/24). Patency of RITA grafts routed through the transverse sinus was similar to patency of other bypasses to non-LAD vessels. Among 12 free grafts that used segments of the RITA, 10 were patent (83%). Of additional saphenous vein grafts, 69% (39/56) were patent at restudy. CONCLUSIONS: This study supports the continued use of the RITA as a conduit for coronary artery revascularization. In our experience, the position of the target vessel is a more important determinant of graft patency than the side of the internal thoracic artery selected for use as a bypass graft.

Coronary Angiography↗

Protamine induces vasorelaxation of human internal thoracic artery by endothelial NO-synthase pathway.

BACKGROUND: Protamine is commonly used in cardiac surgery to reverse the anticoagulant effects of heparin. We investigated the role of different nitric oxide synthase pathways in the response of the human internal thoracic artery to protamine and evaluated whether heparin could prevent this effect. METHODS: A tension-recording method was used to obtain baseline measurements of contractions of human internal thoracic artery rings achieved with norepinephrine. Isolated internal thoracic artery rings were suspended in two organ chambers. One contained Krebs-Henseleit solution and served as control. The other contained a heparin or Nomega-Nitro-L-arginine (L-NAM, an inhibitor of both endothelial and inducible nitric oxide synthase) or a specific inhibitor of inducible nitric oxide synthase, aminoguanidine. Increasing doses of protamine were added to both chambers and dose-response curves were obtained. RESULTS: Protamine was found to relax contracted internal thoracic arteries 56% +/- 4.7% of baseline measurements in a concentration-dependent manner. When L-NAM was added, protamine caused only a slight decrease of tension. There were no differences in the relaxing effect of protamine in the presence of aminoguanidine or heparin. CONCLUSIONS: Protamine induces nitric oxide-dependent relaxation of the internal thoracic artery by activation of endothelial nitric oxide synthase pathway. Heparin could not prevent this relaxing effect of protamine.

Coronary Artery Bypass↗

Comparative histological and biometric study of the coronary, radial and left internal thoracic arteries.

In an attempt to elucidate the causes of occlusion of radial arteries used for coronary artery bypass grafts and to improve the results of these procedures, we studied the biometry and histology of the coronary, radial and left internal thoracic arteries. These arteries were harvested from 20 cadavers (13 males, 7 females). The specimens were calibrated to the various bypass graft sites using coronary calibrators, and were then submitted to histological examination to determine the structure and innervation of the vessel wall. No correlation was observed between the internal calibers of these various arteries, with the exception of the anterior interventricular and right coronary arteries. Intimal changes and the presence of atheromatous plaque were observed in coronary and radial arteries, but never in the internal thoracic artery. Like the coronary arteries and their branches, the radial artery is a muscular artery. Aging of muscular arteries results in thickening of the intima, which becomes fibrotic due to migration of myocytes from the media and duplication of the internal elastic lamina. The media becomes fibrous, hypertrophic or atrophic. The walls of the radial and coronary arteries contain several adventitial nerves (sympathetic and parasympathetic nerve fibers), but these nerve fibers were not observed in the wall of the left internal thoracic artery. In contrast, the internal thoracic artery, like the aorta, is an elastic artery. Aging of elastic arteries is first observed between the ages of 20 and 29 years and is characterized by loss of one or several elastic laminae of the media and more marked intimal thickening, over a variable length. Even if a radial artery's caliber is similar to that of the coronary artery, histological evolution and graft patency depend on its muscular identity.

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Arterial myocardial revascularization with in situ crossover right internal thoracic artery to left anterior descending artery.

BACKGROUND: The extra length obtained by skeletonizing the internal thoracic arteries (ITAs) enables versatile use of in situ bilateral ITAs for coronary artery bypass grafting, as the longer skeletonized right ITA more easily reaches the anastomotic site on the left anterior descending coronary artery. METHODS: Between April 1996 and November 1999, 365 consecutive patients underwent revascularization with bilateral in situ ITAs (29% of 1,250 grafting procedures performed with both ITAs in our department during this period). The right ITA was routed anterior to the aorta to graft the left anterior descending coronary artery, and the in situ left ITA was used to graft circumflex branches. Right coronary artery branches were grafted with right gastroepiploic artery or saphenous vein graft. The right ITA crossed the midline above the aorta at the most cranial point to avoid damage in case of a repeat sternotomy in the future. RESULTS: The operative mortality rate was 2.2% (8 patients). Postoperative morbidity included seven strokes (1.9%), eight sternal wound infections (2.2%), and four perioperative myocardial infarctions (1.1%). Follow-up (6 to 49 months) of 97% of hospital survivors showed a return of angina in 3%. Postoperative coronary angiography (22 patients) revealed a 95% patency rate of both ITAs. One-year and 4-year survival rates (Kaplan-Meier) were 95% and 92.4%, respectively. Important predictors of an early unfavorable event were chronic obstructive pulmonary disease, old age (> or = 70 years), emergency operation, and diabetes. Chronic obstructive pulmonary disease was the only independent predictor of sternal wound infection (odds ratio, 15; 95% confidence interval, 2.8 to 80). It also predicted decreased late survival (hazard ratio, 8.3; 95% confidence interval, 3 to 21.5). CONCLUSIONS: With skeletonized dissection of ITAs, the right ITA easily reaches the left anterior descending coronary artery for left-sided arterial revascularization with in situ bilateral ITAs. This procedure is safe, but we recommend avoiding its use in patients with chronic obstructive pulmonary disease.

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Total arterial off-pump coronary revascularization with only internal thoracic artery and composite radial artery grafts.

OBJECTIVE: Total arterial off-pump coronary artery bypass (OPCAB) grafting with only internal thoracic artery (ITA) and composite radial artery (RA) grafts has been applied extensively to avoid cerebral complications and late vein graft failure. We evaluated the initial experience with this method by clinical and angiographic study. METHODS: Between April 2000 and May 2002, 257 patients underwent OPCAB grafting with this technique. The range of ages at operation was 42 to 86 years (mean, 66.1 +/- 8.6 years). On average, 3.28 +/- 0.86 grafts per patient were completed. More than 4 distal anastomoses were performed in 88 patients (34%). For coronary revascularization, 289 ITA and 555 RA grafts were used. The RA was used as a Y graft in 211 patients, as an I graft (for ITA extension) in 52 patients, and as a K graft (the side of the RA attached to the side of the left ITA) in 28 patients. Sequential bypass grafting was performed with 190 RA and 7 ITA grafts. The sites of distal anastomoses were 256 left anterior descending arteries (30%), 236 posterolateral branches (28%), 144 posterior descending arteries (17%), 106 diagonal branches (13%), 82 obtuse marginal branches (10%), and 19 right coronary arteries (2%). RESULTS: There were 1 operative death (0.4%) due to cerebral hemorrhage and 2 episodes of stroke (0.8%) during postoperative angiography. There were no clinical underperfusion syndromes or new intra-aortic balloon pump insertions. Perioperative myocardial infarction occurred in 12 patients (4.7%), sternal dehiscence in 5 (1.9%), and early coronary intervention in 4 (1.6%). There was no deep wound infection, reexploration for bleeding, or hand ischemia. The actuarial survival rate and the cardiac event-free rate at 2 years were 98.6% +/- 2.4% and 94.2% +/- 0.8%, respectively. Early postoperative angiography revealed a 97.8% (264/270) graft patency of ITAs and 97.9% (512/523) graft patency of RAs in 238 patients. Flow competition of the RA graft was recognized in 22 patients and, as indicated by follow-up angiographic study, did not cause late graft occlusion. CONCLUSIONS: OPCAB grafting with ITAs and composite RAs provides excellent early and intermediate clinical results and graft patency.

Adult↗

[The propriety of bilateral internal thoracic artery grafting in women].

In our institution, the exclusion criteria of the bilateral internal thoracic artery (BITA) grafting include age over 70 years old, obesity, severe diabetes, renal dysfunction and poor preoperative physical activity. The objective of this study is to evaluate propriety of the use of bilateral internal thoracic artery for coronary artery bypass grafting (CABG) in women. Clinical outcome of female patients who underwent BITA grafting (group B-F; n = 50) was compared with that of female patients who underwent single internal thoracic artery grafting (group S; n = 50). In addition, clinical outcome of the male patients who underwent BITA grafting (group B-M; n = 50) was compared with that of group B-F. Between group B-F and S, the age, prevalence of obesity and that of renal dysfunction were significantly different, which was predictable because of the group selection according to the criteria. However, the prevalence of previous myocardial infarction and that of left ventricular dysfunction and the extent of coronary artery disease were not significantly different. Whereas, between group B-F and B-M, preoperative factors were not significantly different except the body size. Intraoperative technical factors, such no of grafts, aortic cross clamp time, cardiopulmonary bypass time, rate of complete revascularization, were not significantly different. In comparison of group B-F with group B-M, the site of anastomosis with arterial grafts were not significantly different. Patency rate of arterial and venous grafts two week after operation was not significantly different. Either postoperative complications, such as reoperation for bleeding, wound complication, low output syndrome, renal dysfunction etc, were not significantly different. One patient (2%) in group B-F and 1 patient (2%) in group B-M died in the hospital (p > 0.05). In summary, BITA can be a viable conduit of choice for CABG in female patients as well as that in male patients. Criteria of the use of BITA is recommended to exclude preoperative risk factors above-mentioned.

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Protecting the endothelial integrity of internal thoracic arteries.

BACKGROUND: Previous functional studies on human internal thoracic arteries, comparing the effect of the traditional harvesting method (occlusion with a clip) with a method leaving the artery perfused, revealed considerably impaired endothelial function associated with enhanced contractility after clipping. We have now investigated whether these observations could be correlated (1) with plasma markers of endothelial dysfunction, and (2) with structural changes in the endothelial layer. METHODS: 32 patients were randomly distributed into groups of clipped and perfused arteries. Arterial blood samples were obtained from both the artery and extracorporeal circulation to determine sP-selectin, sE-selectin, sL-selectin, and thrombomodulin using enzyme-linked immunosorbent assay. Arteries from three patients were examined by scanning electron microscopy. RESULTS: Concentrations of sP-selectin and thrombomodulin were significantly higher in plasma from clipped arteries compared to perfused arteries, whereas sE-selectin and sL-selectin concentrations were similar within the groups. Scanning electron microscopy revealed significant structural changes and loss of endothelial cells in clipped arteries. CONCLUSION: Biochemical and structural results support our findings that leaving the internal thoracic artery perfused preserves endothelial function in the arterial graft.

Biomarkers↗

In situ right internal thoracic artery graft via transverse sinus for revascularization of posterolateral wall: early results in 116 cases.

The in situ right internal thoracic artery graft brought through the transverse sinus was used to revascularize the posterolateral wall in 116 patients. Its advantages were assessed retrospectively. The graft was anastomosed to the circumflex marginal branch in 70 patients (60%) or to the posterolateral branch in 41 patients (35%). One patient died (mortality rate 0.9%). Perioperative myocardial infarction occurred outside the territory of the right internal thoracic artery graft in 10 patients, four of whom required mechanical support for hemodynamic deterioration. Postoperative early angiography in 114 patients found the graft to be patent in 97.4%. The ratio of the diameter of the right internal thoracic artery to that of the recipient marginal branch was 0.94 +/- 0.18 (n = 69), and that to the posterolateral branch was 0.88 +/- 0.18 (n = 37) (not significantly different). Results of a postoperative stress test were abnormal in one patient (1/96 tested patients). This retrospective study suggests that the right internal thoracic artery brought through the transverse sinus to revascularize the posterolateral wall provided excellent early patency and good clinical results, even to the most distally located branches. This continues to be our procedure of choice for patients with multivessel coronary disease.

Adolescent↗

Partial right internal thoracic artery harvesting is sufficient for obtuse marginal branch bypass grafting.

My colleagues and I present a method for revascularizing the left anterolateral myocardial wall by using an in situ left internal thoracic artery to left anterior descending coronary artery system and a short proximal segment (3 to 5 cm) of the right internal thoracic artery in Y fashion anastomosed to the in situ left internal thoracic artery to revascularize the obtuse marginal branches. With this technique the left ventricular anterolateral wall can be revascularized with both internal thoracic arteries, leaving a consistent residual blood supply to the right hemisternum.

Anastomosis, Surgical↗

Decreased sternal vascularity after internal thoracic artery harvesting resolves with time: an assessment with single photon emission computed tomography.

OBJECTIVE: We sought to prospectively evaluate the long-term effect of left internal thoracic artery harvesting on sternal vascularity. METHODS: Twelve consecutive patients undergoing primary coronary artery bypass grafting were studied. In all patients a pedicled left internal thoracic artery was harvested. Each patient underwent a preoperative technetium-99m methylene diphosphonate bone scan with single photon emission computed tomography. The ratio of the mean counts per pixel for each side of the sternum was obtained. All patients had early repeat bone scans 6 plus minus 2.4 days postoperatively and late repeat bone scans 18.6 plus minus 3.5 months after the operation. Ratios of unilateral sternal uptakes were compared between the different scans. One patient died during follow-up and was excluded from the study. RESULTS: There was a significant decrease in flow to the left hemisternum in the early postoperative scan compared with that in the preoperative scan (P <.001). At late follow-up scans, flow to the left hemisternum had returned to normal (P =.119). Midterm clinical follow-up demonstrated 3 superficial wound infections. No musculoskeletal pain existed at the time of follow-up, but 3 patients had numbness or tingling at the skin area corresponding to the site from which the left internal thoracic artery was harvested. CONCLUSIONS: Acute postoperative sternal ischemia caused by harvesting of a pedicled left internal thoracic artery is temporary and resolves with time.

Aged↗

A technique to protect the left internal thoracic artery.

The natural tendency of the harvested in-situ left internal thoracic artery is to assume a position near the anterior midline of the mediastinum, adjacent to the posterior sternal table. This repositioning of the left internal thoracic artery makes sternal reentry for redo myocardial revascularization (or other open cardiac procedures) hazardous. A technique of posterior and lateral repositioning of the mobilized in-situ left internal thoracic artery by creating a thymic flap and a pleuromediastinal groove is presented.

Humans↗

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.

Aged↗

Off-pump coronary artery bypass grafting for the circumflex coronary artery via the left thoracotomy in redo CABG with the patent left internal thoracic artery graft to the left anterior descending artery.

Five patients had undergone off-pump coronary artery bypass grafting (CABG) as redo CABG via the left thoracotomy for the lesions of the left circumflex coronary arteries. In all patients, the internal thoracic artery (ITA) grafts to the LAD were well patent and acting significantly important in coronary circulation, however, ischemia due to the lesion of the LCX was significant. The saphenous vein grafts or the radial artery grafts were used as the materials of the grafts. The proximal ends of these grafts were anastomosed to the descending aorta. The procedures were completed successfully in all the patients and the excellent patency was shown angiographycally even in the long-term period after the surgery. Necessity of graft surgery only for the LCX lesion would be a rare occasion for a surgeon; however, these results suggest that the procedure is simple and less risky, which would encourage the surgeon to perform it in clinical situation.

Aged↗

Routine use of bilateral skeletonized internal thoracic artery grafts in middle-aged diabetic patients.

BACKGROUND: The purpose of this study was to determine whether middle-aged diabetic patients aged less than 70 years could have routine use of bilateral skeletonized internal thoracic artery grafting without an increased surgical risk. METHODS: Between January 1997 and December 2003, 712 consecutive patients aged less than 70 years underwent bilateral internal thoracic artery grafting. Among these, 164 were diabetic and underwent bilateral internal thoracic artery grafting without other preoperative selection than age. The postoperative results of these 164 nonselected consecutive diabetic patients were compared to these of the 548 nondiabetic patients. RESULTS: The operative mortality rate was 4.3% (7 patients) in the diabetic group and 2.4% (13 patients) in the nondiabetic group (p = not significant [NS]). Deep sternal wound infection was observed in 2 patients (1.1%) in the diabetic group and in 6 patients (1.2%) in the nondiabetic group (p = NS). There were no significant difference in the morbidity rate between the two groups except for renal failure without dialysis (6.7% in the diabetic group vs 2.0% in the nondiabetic group, p < 0.01). CONCLUSIONS: Routine use of bilateral internal thoracic artery grafting was performed in nonselected middle-aged diabetic patients without increased morbidity. The low rate of deep wound infections could be related to the skeletonized technique of internal thoracic artery harvesting.

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Passing the right internal thoracic artery through the transverse sinus.

We describe a simple reliable method to pass the right internal thoracic artery safely through the transverse sinus. At first, a 4-mm-wide vascular tape is passed through the transverse sinus. The cut end of the right internal thoracic artery is then attached to the right end of the tape with a hemoclip. Pulling the left end of the tape leftwards can ensure the passage of the right internal thoracic artery without any risk of twisting.

Humans↗

[Comparative assessment of the use of skeletonized and un-skeletonized internal thoracic artery for myocardial revascularization].

BACKGROUND: Skeleting of internal thoracic artery widens possibilities of a surgeon during mammary-coronary bypass grafting but this procedure is associated with augmented risk of damage of internal thoracic artery (ITA). MATERIAL AND METHODS: ITA was used for creation of anastomosis with anterior interventricular artery in 151 patients. It was harvested on pedicle in 82 (group 1) and subjected to skeleting in 69 (group 2) patients. All operations were performed with cardiopulmonary bypass. In group 2 ITA conduits were more frequently used for grafting distal anterior interventricular artery. RESULTS: There were 3 and 0 deaths in groups 1 and 2, respectively. Rates of nonfatal postoperative complications were similar in both groups. Spasms of ITA grafts were more frequent in group 1. CONCLUSION: Skeleting of ITA for mammary coronary bypass grafting compared with its harvesting on pedicle was not associated with increased risk of complications or elevated mortality in early postoperative period.

Blood Flow Velocity↗

Effect of skeletonizing dissection on the internal thoracic artery.

BACKGROUND: Skeletonization of the internal thoracic artery (ITA) produces greater length for coronary bypass grafting. We studied the effect of skeletonization on the morphology, histology, and tissue viability of the ITA wall. METHODS: Six mongrel dogs underwent unilateral ITA dissection; the contralateral ITA was the control. Study periods were 3 weeks (n=3) and 12 weeks (n=3). At sacrifice, the entire anterior chest wall was removed and dynamically fixed with formalin. Extensive histologic comparisons were performed on three tissue blocks taken from each ITA, 2, 8, and 24 cm from their origin. RESULTS: Flows at the end of the study were comparable to measurements taken during operation, immediately after skeletonization. Grossly, the ITA wall was not injured by skeletonization and there was no adventitial hematoma or bleeding from the sealed branch ends. Microscopic observations showed intact, normal wall structures. Histologic data showed no major significant difference between controls and skeletonized ITAs. CONCLUSIONS: Careful skeletonizing dissection is not detrimental to the integrity of ITAs, which justifies their use for myocardial revascularization.

Animals↗

Myocardial revascularization using both attached internal thoracic arteries. Mid-term clinical evaluation of 117 cases.

The current trend in myocardial revascularization is to use arterial grafts in most, if not all cases. The right internal thoracic artery was a logical choice once the left internal thoracic artery patency on the LAD was known. This study presents our experience of using both attached internal thoracic arteries (ITA). Between January and October 1990, 159 myocardial revascularizations were performed in our department. In 117 cases, bilateral ITA grafting was used with non exclusion criteria. There were 100 male and 17 female patients, with a mean age of 61 +/- 8. The LITA was anastomosed to the LAD in 44 cases, and to the marginal artery in 74. The RITA was anastomosed to the LAD in 68 cases, to the marginal artery in 47 and to the right coronary artery in 2. An average of 3.5 bypasses per patient, including saphenous vein grafts, were performed. Six patients (5%) died within 30 days. Four patients (3.4%) were diagnosed as having periperative myocardial infarcts. There were no reoperations for bleeding. One patient (0.9%) presented a sternal wound infection. Mean follow-up was 18 +/- 7 months. Six patients died during the follow-up and the survival rate was 91%. Ninety-five patients (91%) were symptom-free, 9 patients had a recurrent angina. Postoperative coronary angiography was performed in 11 patients (10%).(ABSTRACT TRUNCATED AT 250 WORDS)

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