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Factors affecting patency of internal thoracic artery graft: clinical and angiographic study in 1434 symptomatic patients operated between 1982 and 2002.

OBJECTIVE: The purpose is to define factors influencing long-term patency of the internal thoracic artery (ITA) to optimize the operative strategy. METHODS: 1482 left internal thoracic artery (LITA) and 636 right internal thoracic artery (RITA) symptom-directed angiograms were studied in 1434 patients. Data were prospectively collected from patients who had primary coronary artery bypass surgery during the period 1982-2002. The mean age of patients was 59 years; 85% were male. The mean period from operation to re-angiogram was 80 months. LITA was grafted to left anterior descending coronary artery (LAD) in 82% of cases, RITA to right coronary artery (RCA) in 40% and circumflex artery in 35% of cases. Graft failure was defined as > or =80% stenosis. RESULTS: 96.3% of LITA and 88.1% of RITA grafts were patent. No patient variables were significantly associated with graft patency (age, gender, diabetes, hypertension, LVEF, NYHA, AMI). Target coronary artery was associated with patency of both LITA and RITA grafts with maximum patency when grafted to LAD (P = 0.02) RITA had the worst patency to RCA, patency for the left system was identical to LITA. Proximal anastomosis to aorta (free RITA) had significantly better patency when compared with in situ RITA to RCA system (P = 0.005) while similar patency when grafted to left system. ITA diameter and target artery diameter were not associated with graft patency. Recent operations had better RITA patency (P = 0.03). The interval from operation to angiogram was not associated with ITA patency (96% patency for LITA and 88% patency for RITA, remained stable when studied at <1, 1-4, 5-9, 10-14 and >15 years). CONCLUSIONS: Even in a patient cohort that had adverse symptoms, excellent LITA and RITA patency was achieved which almost remained constant through all time intervals studied.

Aged↗

Analysis by early angiography of right internal thoracic artery grafting via the transverse sinus : predictors of graft failure.

BACKGROUND: There has been debate regarding whether technically demanding right internal thoracic artery (RITA) grafting via the transverse sinus can be extensively applied to patients in high-risk groups, such as patients with a small body size, elderly patients, and woman with relatively smaller coronary artery and internal thoracic artery (ITA) diameters. METHODS AND RESULTS: Of the 1456 patients who underwent isolated coronary artery bypass grafting between January 1989 and December 1998 at Kumamoto Central Hospital, 393 patients (mean age, 62.4+/-9.0 years) with the RITA anastomosed to the major branches of the circumflex artery were studied. Left ITA grafting was performed in 384 patients, and in 369, the in situ left ITA was anastomosed to the left anterior descending coronary artery using standard methods. Early postoperative angiography was performed in 381 patients. The RITA was occluded in 4 patients, and string-like artery and significant stenosis were present in 11 and 7 patients, respectively; RITA graft patency was thus 94.1%. Of the preoperative variables and angiographic data, simple and multiple logistic regression analyses identified decreased severity of native stenosis, diffuse sclerosis of native vessels, and residual side branches of the ITA as independent predictors of nonfunctional grafts. The method of ITA grafting did not influence the patency of the graft. CONCLUSIONS: The excellent patency rate demonstrated by this study, the largest angiographic study to date of RITA grafting via the transverse sinus, indicates that this technique can provide reliable revascularization of the left ventricle and that it has the potential to be applied to a wide variety of patients with diseased circumflex arteries.

Adolescent↗

The right internal thoracic artery graft--benefits of grafting the left coronary system and native vessels with a high grade stenosis.

OBJECTIVE: The left internal thoracic artery (LITA), when grafted to the left anterior descending artery (LAD), is generally accepted as the conduit of choice for coronary artery bypass grafting (CABG). In contrast, the role and efficacy of the right internal thoracic artery (RITA), despite its long-term use as a coronary artery graft, is relatively less understood. Accordingly, in this study, we sought to assess the utility of the RITA as a coronary conduit by examining the long-term patency of both in situ and free RITA grafts and analyzing the association between intraoperative graft and coronary artery variables. METHODS: Nine hundred and sixty-two patients (LITA 962, RITA 432) who had CABG between 1985 and 1998 and underwent re-angiography for evidence of myocardial ischemia were included in this observational analysis. The diameter of the internal thoracic artery (ITA), the presence of a proximal anastomosis with the aorta, the location of the anastomosis with the coronary artery, and the coronary artery diameter, were recorded at the initial procedure. The follow-up was 67.0+/-39.4 months (mean+/-SD, range 0.1-169.5). The relationship between intraoperative variables and graft patency was assessed using Cox proportional hazard models. RESULTS: Highest RITA failure rates were associated with grafting a native coronary artery with a stenosis of less than 60% compared with 80-100% (RR 3. 8 (95% CI, 1.9-7.2) P=0.0001). Grafts to non-LAD arteries had a higher risk of failure, the highest risk ratio being associated with grafting the right coronary artery (RR 4.0 (95% CI, 0.9-17.4) P=0.06)). Free compared with in situ grafts were also associated with a higher risk of failure with this result bordering on statistical significance (RR 1.9 (95% CI, 1.0-6.0) P=0.06)) CONCLUSION: Preference should be given to grafting arteries with a high grade stenosis or occlusion, to grafting left rather than right coronary arteries, and to using in situ rather than free ITA grafts. Passing the RITA to the left, either anterior to the aorta or through the transverse sinus, did not influence patency.

Coronary Angiography↗

Comparative study between the gastroepiploic and the internal thoracic artery as a coronary bypass graft. Size, flow, patency, histology.

Ninety-two gastroepiploic artery (GEA) and 322 internal thoracic artery (ITA) grafts which underwent postoperative angiography (0.5-24 postoperative months, mean 2.0 months) were compared. The sites of GEA anastomosis were 5 left anterior descending, 3 diagonal, 16 circumflex and 68 right coronary arteries and for ITA grafts, 241 left anterior descending, 40 diagonal, 36 circumflex and 5 right coronary arteries. Patency rates were 96% (88/92) of GEA and 98% (314/322) of ITA, respectively. No focal stenosis in the graft trunk was found in both GEA and ITA except occasional spasm in GEA. Six (6%) GEAs were opacified via the superior mesenteric artery. Mean diameter of grafts just proximal to the anastomosis measured by angiogram was 2.3 mm in GEA and 1.9 mm in ITA (P less than 0.01). Free flow after intraluminal papaverine injection was 90.6 ml/min (50-300 ml/min) in 48 GEAs and 81.3 ml/min (50-150 ml/min) in 98 ITAs. Histology showed normal to mild intimal sclerotic changes in 58 of 63 (92%) GEAs and in 94 of 95 (99%) ITAs. From these results, we concluded that GEA is a suitable conduit and good long term patency similar to ITA grafting can be expected in coronary artery bypass grafting.

Arteries↗

Histology and morphology of 59 internal thoracic artery grafts and their distal anastomoses.

BACKGROUND: The left internal thoracic artery (LITA) is accepted as a superior graft for the left coronary system because of its better long-term patency rate than saphenous grafts. The postsurgical histomorphometric changes at the distal anastomosis of LITA grafts are not well documented. METHODS: The cellular changes within the intima of 59 LITA grafts were analyzed by light microscopy. RESULTS: Grafts implanted 1 week or less (n = 34) showed no postsurgical tissue proliferation. Of the 7 grafts implanted 1 to 8 weeks, only the suture sites exhibited intimal thickening (6 of 7 grafts, 0.08 +/- 0.07 mm). The remaining grafts (n = 18), aged 2 months to 10 years, showed significant intimal thickening at the suture sites (0.39 +/- 0.17 mm) and on the hood (0.29 +/- 0.25 mm), with variable thickening on the floor (10 of 18 left anterior descending coronary arteries, 0.11 +/- 0.12 mm). The graft body showed insignificant intimal changes (10 of 18, 0.03 +/- 0.04 mm), with mild focal atherosclerotic lesions in 2 of 18 late LITA grafts. CONCLUSIONS: Left internal thoracic artery grafts develop fibromuscular intimal hyperplasia primarily around the anastomosis. The response on the hood appears to be a hemodynamic response, secondary to that of the suture sites.

Aged↗

Adrenoceptors of the human internal thoracic artery.

Adrenoceptor function in the human internal thoracic artery (ITA) was characterized in vitro using segments of the artery obtained during coronary bypass operations. Specimens were prepared as isolated arterial rings mounted in a tissue bath, and mechanical activity (isometric tension) was measured in response to drugs. The ITA responded to phenylephrine (PE), epinephrine, and norepinephrine with concentration-dependent contractions. The PE-induced contractions were antagonized by phenoxybenzamine, prazosin, and high concentrations of yohimbine. The ITA was not effectively contracted by clonidine in the concentration range normally associated with alpha 2-adrenoceptor stimulation. The beta-adrenoceptor agonist, isoproterenol, had a weak and variable effect on the ITA; samples from 9 out of 12 subjects did not respond to isoproterenol, whereas samples from 3 subjects responded with relaxations of between 33 and 42%. These in vitro studies indicate that the most important adrenoceptors of the human ITA are alpha-adrenoceptors; this may be relevant for the pharmacologic management of patients undergoing coronary bypass surgery using the ITA.

Adrenergic alpha-Antagonists↗

Chylothorax as a complication of harvesting the left internal thoracic artery in coronary artery bypass surgery.

A patient is described with chylothorax after harvesting the left internal thoracic artery for coronary artery bypass surgery. Conservative treatment with a medium chain triglycerides diet and tube thoracostomy was not only unsuccessful, but also resulted in the complications of malnutrition and empyema. We recommend early surgical treatment of chylothorax after coronary bypass surgery with the use of an internal thoracic artery.

Adult↗

Effect of chronic native flow competition on internal thoracic artery grafts.

Residual competitive flow from the native coronary artery has been proposed as a mechanism that reduces flow in an internal thoracic artery graft (ITA), resulting in narrowing and ultimately failure of the graft. Results from acute experiments have indicated that competitive flow from a fully patent native artery did not abolish ITA graft flow. The present study was designed to examine the consequences of dynamic flow competition between the native vessel and the ITA graft in a chronic model. Fifteen mongrel dogs underwent coronary artery bypass grafting using the pedicled left ITA anastomosed to the normal, fully patent circumflex (CFX) coronary artery. The procedure was performed through a sterile thoracotomy, without systemic cardiopulmonary bypass, using a brief local occlusion to construct the anastomosis. Intraoperatively, ITA flow was measured in situ on the chest wall, before the pedicle was mobilized. Internal thoracic artery graft and distal CFX flow were measured after the anastomosis was completed, with and without brief occlusion of the proximal CFX. Angiography was performed 72 hours, 4 weeks, and 8 weeks later; graft patency and diameter were evaluated. After 8 weeks, open-chest direct flow measurements comparable with the intraoperative assessment were obtained. Two grafts (13%) occluded early, the technical result of poor anastomotic construction. In the 13 remaining animals, all grafts were widely patent at all time points. Internal thoracic artery flow in situ averaged 10.9 +/- 7.8 mL/min (mean +/- standard deviation), and was maintained after grafting (11.5 +/- 4.4 mL/min; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

What is the mortality and recuperative difference of bilateral versus single thoracic artery coronary revascularization in patients with reoperation or over 80 years of age?

BACKGROUND: We examined whether bilateral internal thoracic artery revascularization (BITA) is safe for reoperative coronary revascularization (reop CABG) or primary CABG at age > or = 80 (CABG > or = 80 yrs) as, these two groups are thought to be at higher risk for death or sternal infection. METHODS: We analyzed 329 such patients between January 1, 1993 and March 31, 2002. These are subgroups of 3200 prospectively New York State risk stratified patients for BITA or SITA (single internal thoracic artery revascularization) of equivalent preoperative risk. In 37/39, BITA > or = 80 since 1996 (1996 > or = 80) the microscope was used and the free right internal thoracic artery was anastomosed to the aorta. Long-term survival was analyzed by Kaplan-Meier curves and in particular among the 36 patients between 1996 and 1997, who were operated five and six years ago (1997 > or = 80). CONCLUSIONS: Mortality and recuperative difference of BITA versus SITA in the reop CABG and CABG > or = 80 years are negligible, as there was no significant difference in hospital mortality, sternal infections, LOS, or Kaplan-Meier survival curves and average long-term survival. However BITA appears to have long-term advantage over SITA in the newer period and beyond 48 months (1996-1997 > or = 80).

Aged↗

[Normal values for the internal thoracic artery by Doppler ultrasound and modification of the Doppler curve after bypass to the left anterior descending artery].

AIM: In coronary heart disease, the surgical therapy of choice is the construction of an artenal bypass of the left anterior descending artery (LAD) using the internal thoracic artery 8ITA). We define age dependent normal values for the ITA such as diameter of the lumen (LD), peak systolic (Vs) and diastolic (Vd) flow velocity and the ratio of these two values (SDR) measured by duplex ultrasound. Furthermore, the modification and pathological changes of the Doppler curve after minimal invasive bypass of the LAD (MIDCAB) are described. MATERIAL AND METHODS: 96 people, age 18 - 87 years, subdivided into 6 age groups were examined by duplex to define the normal values of the ITA, and 55 patients (mean age 63 +/- 10 years, 48 men, 7 women) were evaluated after MIDCAB-surgery to describe the postoperative modification of the Doppler curve. The examinations were performed using a 4 - 7 MHz linear ultrasound transducer in the right and left 1. or 2. intercostal space parasternally. RESULTS: In all 96 people, the ITA was detectable on both sides presenting a typical bi- or triphasic Doppler flow profile. A linear age dependent increase in the LD of 1.95 +/- 0.15 mm (right ITA) and 1.93 +/- 0.27 mm (left ITA) respectively to 2.65 +/- 0.48 mm and 2.55 +/- 0.43 mm was found. No significant side difference was found for Vs and Vd, nor were there any age dependent differences for Vs. The SDR showed an age dependent linear increase on the right side from 3.5 +/- 1.1 to 6.1 +/- 2.2, p < 0.0012, and on the left from 3.9 +/- 1.2 to 6.7 +/- 1.7, p < 0.0001. Postoperatively, the Doppler spectrum was modified into a mono- or biphasic Doppler curve with a reduced Vs and an increased Vd resulting in a significantly decreased SDR on the left side compared with the right side (1.3 +/- 0.8 vs. 5.4 +/- 2.0, p < 0.00001). Three patients with angiographically proven graft failure had an SDR of 2.6 - 5.2 (mean 3.8), as opposed to a value of < 2.0 in case of a patent bypass. An SDR > 2.0 has a sensitivity of 100 % and a specificity of 97 % in the detection of a haemodynamically relevant (>70 %) ITA-graft-stenosis. CONCLUSIONS: With rising age, there is an increase in the LD of the ITA and the peripheral resistance, expressed as SDR. After MIDCAB surgery the former triphasic Doppler flow curve changes into a mono- or biphasic curve corresponding to the coronary blood flow. An SDR >2.0 is a strong indicator of bypass failure.

Adolescent↗

Does potassium channel opening contribute to endothelium-dependent relaxation in human internal thoracic artery?

Opening of potassium channels can cause hyperpolarization and relaxation of vascular smooth muscle cells. The aim of this work was to investigate the contribution of potassium channel activation to vasorelaxation in internal thoracic artery taken from patients undergoing coronary artery bypass graft surgery. Relaxations to carbachol and sodium nitroprusside were studied in isolated rings of internal thoracic artery in the absence and presence of nitric oxide synthase inhibitors and potassium channel blockers. The nitric oxide synthase inhibitors Nomega-nitro-L-arginine methyl ester and NG-monomethyl-L-arginine abolished relaxations to carbachol. Relaxations to both carbachol and sodium nitroprusside were attenuated in the presence of raised extracellular potassium and the potassium channel blockers charybdotoxin, iberiotoxin and tetraethylammonium. Neither apamin nor glibenclamide modified relaxation. ODQ (1H-[1,2,4]oxadiazolol-[4,3a] quinoxalin-1-one), an inhibitor of soluble guanylate cyclase, abolished relaxation to carbachol in rings from some but not all subjects. These results suggest that potassium channel opening may make a small contribution to endothelium-dependent vasorelaxation in internal thoracic artery. The potassium channels had characteristics consistent with those of large-conductance calcium-dependent potassium channels.

Aged↗

Isolated bypass grafting of the left internal thoracic artery to the left anterior descending coronary artery: late consequences of incomplete revascularization.

OBJECTIVE: Multiple strategies to achieve some degree of myocardial revascularization are available. In some, less complete revascularization is accepted to limit invasiveness. To examine the issues of incomplete revascularization, we assessed the long-term impact of additional non-left anterior descending coronary artery stenoses in patients undergoing only grafting of the left internal thoracic artery to the left anterior descending coronary artery. METHODS: A total of 2067 patients underwent primary isolated grafting of the left internal thoracic artery to the left anterior descending coronary artery from 1971 to 1997. Of these, 26% and 13% had 2- and 3-system disease, respectively. Multivariable analyses of survival and reintervention were performed in the hazard function domain for 27,683 patient-years of follow-up (mean 14 +/- 6.7). RESULTS: Survival was 99%, 88%, and 62% at 1, 10, and 20 years. Right coronary artery or left circumflex system disease of 50% or more (P =.02) and particularly high-grade (>/=70%) left circumflex (P =.01) and proximal right coronary artery disease (P =.01), as well as any degree of left main trunk stenosis (P <.0001), were associated with reduced long-term survival. Compared with 75% 20-year survival in patients with no non-left anterior descending disease, those with either left circumflex or left main trunk disease experienced a 44% survival, and those with proximal right coronary artery disease, 42%. The most common stated reason for incomplete revascularization was small vessel size. Freedom from reintervention was 89% and 65% at 10 and 20 years, respectively. High-grade left main trunk disease, but, in contrast, mid or distal disease of the right coronary artery, and not left circumflex disease, were risk factors for reintervention. CONCLUSIONS: These findings call into question the long-term appropriateness of interventions whose strategy includes leaving unrevascularized segments in territories not in the distribution of the left anterior descending coronary artery.

Adult↗

[Macroscopic vascularization of the adult sternum. Implications of removal of the internal thoracic arteries].

The most of the arterial vascularisation of the adult sternum is on the dependence of the internal thoracic arteries. The best results of the aorto-coronary by-pass starting from this arteries are however subjected to more infectious complications. The study of this arterial supply, in "surgical" conditions, after sternotomy and ablation of one or two internal thoracic arteries show this devascularization. The residual arterial supply is only constituted by thin branches coming from intercostal arteries.

Adult↗

Internal thoracic artery grafts for the entire heart at a mean of 12 years.

BACKGROUND: There is consensus today that the long-term results of bypassing the left anterior descending artery with an internal thoracic artery (ITA) graft are superior to those of a saphenous vein graft. Our hypothesis for this study was that three-vessel revascularization with only ITA grafts would also give excellent results. METHODS: Using our previously described techniques to enhance the length of ITA grafts by skeletonization and high mediastinal mobilization, we were able to perform tension-free, three-vessel revascularization using only ITA grafts in 125 (83%) of a consecutive series of 150 patients with three-vessel occlusive coronary disease. We followed 100% of these 125 exclusive ITA graft patients (average of 3.9 anastomoses per patient) to their time of death (59; 47.2%) or current living status (66; 52.8%). RESULTS: Combined intraoperative graft flows averaged 225 mL/min. Of the 125 patients in this study (average age, 63.5 years), 121 (96.8%) lived beyond 40 days. Of these 121 patients, 55 (45%) died at a mean of 7 years postoperatively and 66 (55%) are still living at a mean of 12.1 years. Of these 121 patients, 112 (93%) had angina at baseline. Of these 112, 92 (85%) were angina free at a mean of 9.1 years postoperatively. Freedom from infarction was 100% at 5 years and 97% at 10 years. Freedom from reintervention was 90% at a mean of 9.8 years. CONCLUSIONS: Use of ITA grafts for three-vessel coronary revascularization provides excellent results and is both practical and appropriate for many patients.

Aged↗

Aortic valve replacement after midline-crossed internal thoracic artery grafting.

In the presence of a midline-crossed internal thoracic artery graft, a median sternotomy may jeopardize the graft and compromise hemodynamics. We report successful aortic valve replacement using a "staircase" thoracotomy and hypothermic axillary perfusion with balloon aortic occlusion in 2 men who had patent right internal thoracic artery grafts that was previously anastomosed to the left anterior descending coronary artery.

Aortic Valve↗

Midterm results of free internal thoracic artery grafting for myocardial revascularization.

BACKGROUND: This study investigated the midterm results after free internal thoracic artery (FITA) grafting for coronary artery bypass grafting. METHODS: Between 1988 and 1995, coronary artery bypass grafting and postoperative graft angiography were performed in 337 patients, of whom 56 patients were treated with 57 FITA grafts. We examined the postoperative graft patency of FITA grafts compared with in situ internal thoracic artery (IITA) grafts, and the late results in the patients receiving at least one FITA graft (FITA group) were compared with those in the patients receiving only IITA graft (IITA group). RESULTS: The early postoperative graft patency rate was 93.2% for the FITA grafts and 96.0% for the IITA grafts (not significant [NS]). Patients underwent sequential graft angiography at 29.5 months postoperatively (25 FITA and 89 IITA). The late graft patency rate was 100% and 92.1%, respectively (not significant). The cardiac death-free survival rate at 5 years was 93.5% in the FITA group and 96.6% in the IITA group (not significant), and the angina-free survival rate at 5 years was 80.6% and 83.2%, respectively (not significant). CONCLUSIONS: The FITA provides late results comparable with those attained with IITA.

Anastomosis, Surgical↗