Evaluation of an internal thoracic artery as a coronary artery bypass graft by intercostal duplex scanning ultrasonography

OBJECTIVES: Although angiography is often used to determine whether the internal thoracic artery is appropriate as a coronary bypass graft, but use of duplex scanning ultrasonography for this purpose is not yet widespread. METHODS: The internal diameter and flow of the internal thoracic artery were measured using intercostal duplex scanning in 100 patients during April 1995. The ultrasonographic device (sonos 2000, Hewlett Packard) used had a linear probe delivering a frequency of 7.5 MHz. Bilateral internal thoracic arteries and their blood flow were imaged clearly in all subjects. Diameter was compared by angiography and duplex scanning ultrasonography in 20 patients. RESULTS: The average internal diameter of internal thoracic artery was 2.19 +/- 0.46 mm (right) or 2.13 +/- 0.32 mm (left) in men and 2.05 +/- 0.44 mm (right) or 2.09 +/- 0.42 mm (left) in women. The gender difference was statistically significant (p = 0.05). The maximum systolic blood flow velocity through the internal thoracic artery was 0.85 +/- 0.34 m/s (right) or 0.84 +/- 0.36 m/s (left) in men and 0.87 +/- 0.28 m/s (right) or 0.82 +/- 0.28 m/s (left) in women. The average internal thoracic arterial blood flow (F) was 54.6 +/- 29.0 ml/min (right) or 50.9 +/- 28.8 ml/min (left) in men and 56.8 +/- 38.2 ml/min (right) or 58.2 +/- 33.4 ml/min (left) in women. Duplex scanning ultrasonography using an intercostal approach enables easy imaging of bilateral internal thoracic arteries and visualizes entire internal thoracic artery structure by simply changing the probe position. CONCLUSION: Intercostal duplex scanning ultrasonography is thus recommended for reliable evaluation of the internal diameter and blood flow of the internal thoracic artery.     

Evaluation of the flow characteristics of an internal thoracic artery graft after coronary artery bypass grafting by intercostal Duplex scanning ultrasonography

AIM: We previously reported intercostal duplex scanning ultrasonography to be a reliable technique for the evaluation of the internal thoracic artery (ITA). The purpose of this study was to determine the flow characteristics of the ITA graft using this technique. METHODS: We evaluated the flow characteristics of 69 ITA grafts who underwent coronary artery bypass grafting by this technique. The internal diameter, mean systolic and diastolic velocity, total flow volume and diastolic fraction were all thus obtained. RESULTS: One occluded graft was found during the follow-up. The mean systolic velocity significantly decreased after the operation (P=0.0001) and the mean diastolic velocity significantly increased both just after the operation (P=0.0002) and 1 year later (P=0.0283). The average diameter of the ITA graft after the operation (1.70+/-0.39), at 1 year (1.73+/-0.29) and at 2 years thereafter (1.66+/-0.27 mm) all significantly decreased in comparison to the preoperative value (2.30+/-0.35 mm) (P=0.0001). The average total flow volume after the operation (35.8+/-22.2), and at 1 year (29.4+/-16.5) and 2 years thereafter (23.4+/-12.7), respectively, were significantly decreased in comparison to the preoperative value (59.4+/-28.6 mL/min) (P=0.0001). However, the average diastolic fraction which was 25.1+/-10.5% before the operation significantly increased after the operation (54.5+/-12.0, 53.2+/-11.2 at 1 year and 50.4+/-9.3 at 2 years) (P=0.0001). CONCLUSION: This technique is thus considered to be a useful noninvasive for the postoperative follow-up of the graft function. A significant increase in the diastolic fraction is thought to be important for maintaining long term graft patency.     

Postoperative mediastinitis after the coronary artery bypass grafting using internal thoracic artery graft

It has been pointed out in general that the resistance against infection is decreased in the diabetic patients. This problem is very important in patients undergoing major surgery. In cardiovascular surgery, the median wound infection may result in life threatening sequelae. We have used the internal thoracic artery as the appropriate graft for its excellent long-term patency. In this series of the diabetic patients who underwent coronary artery bypass grafting with bilateral internal thoracic artery grafts, the incidence of postoperative mediastinitis was significantly higher than other cases. Therefore the use of bilateral internal thoracic artery grafts should be avoided, if possible in the diabetic patients.     

Bovine internal thoracic artery graft. Successful use at urgent coronary bypass surgery

Bovine internal thoracic artery grafts (Bioflow) were successfully utilized in two patients for emergency coronary artery bypass grafting (CABG). One patient was an 80-year-old man with severe varicose veins and a calcified ascending aorta. Heart failure occurred after triple CABG with bilateral internal thoracic and gastroepiploic arteries. The addition of a Bioflow graft to the circumflex artery restored good cardiac function. The second case was a 54-year-old man whose patent old saphenous vein graft was accidentally injured at reoperation. Emergency use of the Bioflow to bypass the right coronary artery in combination with the right gastroepiploic artery graft to the anterior descending artery resulted in an excellent outcome. The two Bioflow grafts were patent at the 20th and 10th postoperative days, respectively. These cases strongly suggest the efficacy of Bioflow during emergency situations in CABG.     

Off-pump coronary artery bypass grafting using in-situ right internal thoracic artery extended with radial artery as I-composite graft

OBJECTIVE: The purpose of this study is to assess the feasibility of utilizing the proximal right internal thoracic artery (RITA) extended with the radial artery (RA) as I-composite graft (RITA-RA graft) in off-pump coronary artery bypass grafting (OPCAB), which preserves the left internal thoracic artery to the left anterior descending artery as an isolated graft and the ascending aorta no-touch technique. METHODS: Between January 2002 and August 2006, 37 patients (aged 67.4+/-7.5 years, 86.5% male) underwent OPCAB using RITA-RA graft. All grafts were harvested in a skeletonized fashion. RITA transected at the middle portion was extended with entirely dissected RA. RITA-RA graft was anastomosed to 1 or 2 lateral artery in a parallel sequential pattern. RESULTS: The total number of distal anastomoses of RITA-RA graft was 48. The early graft patency rate was 97.9%. Five cases (13.5%) needed intra-aortic balloon pumping support during operation. Only 1 patient (2.7%) required ventilator support longer than 24 hours. The percentage of patients requiring homologous blood transfusion was 13.5%. There was no cerebrovascular accident or mediastinitis in the postoperative course. All patients were discharged from hospital. CONCLUSIONS: OPCAB using RITA-RA graft is feasible and safe. It provides satisfactory early clinical and angiographic outcomes.     

The left internal thoracic artery and radial artery composite graft in off-pump coronary artery bypass grafting.

Arterial multivessel bypass grafting without extra corporeal circulation and manipulation of the ascending aorta should be a good surgical option for the treatment of coronary artery disease. An internal thoracic artery (ITA)-radial artery (RA) composite graft was used for this purpose. Between July 2000 and October 2001, we employed the LITA-RA composite graft for off-pump coronary artery bypass in 15 cases. Mean patient age was 71.3 +/- 5.8 years old. Left main trunk disease was present in six patients and triple-vessel disease in four patients. Preoperative concomitant disease was renal dysfunction in three cases, cerebrovascular disease in four and diabetes mellitus in five cases. Two patients had a so-called bad aorta. Twelve elective operations and three urgent operations were carried out for unstable angina. Two to four (mean 2.6 +/- 0.7) anastomoses were performed per patient. Complete revascularization was achieved in 12 out of 15 patients. Mean operating time was 335 +/- 53 min. Mean intraoperative blood loss was 595 +/- 375 ml and nine patients underwent the operation without blood transfusion. There was no PMI, no brain disorder, and no death. Postoperative coronary angiography in all patients documented a good patency rate (LITA 15/15, RA 21/21, right gastroepiploic artery (RGEA) 2/2, and saphenous vein graft (SVG) 0/2). LITA-RA composite grafting in off-pump coronary artery bypass enables arterial multivessel revascularization using an aortic no touch technique. This can be done with minimum postoperative complications and without risk of cerebral infarction even in patients at high risk for extracorporeal circulation (ECC).     

Anterior intercostal nerve damage after coronary artery bypass graft surgery with use of internal thoracic artery graft

BACKGROUND: The prevalence of intercostal nerve damage associated with coronary artery bypass graft-internal thoracic (mammary) artery surgery is unknown. METHODS: A total of 37 consecutive patients with coronary artery bypass graft surgery (all with left internal thoracic artery graft) who were attending a cardiac-related exercise program underwent a thorough examination. Nerve damage was considered to be "definite" in the presence of two consistent and well-demarcated sensory abnormalities over the anterior chest wall within the T1 to T6 anterior intercostal nerve territory, and was considered "possible" in the presence of one such abnormality. RESULTS: Definite nerve damage was detected in 73% of the subjects, and possible nerve damage was found in another 11% at the site of internal thoracic artery harvesting. Protracted postoperative pain or unpleasant sensations, usually subsiding by 4 months, were reported by recollection by 81% of the subjects. Overall, the prevalence of persistent pain in those with definite nerve damage 5 to 28 months after surgery was 15%. CONCLUSIONS: Intercostal nerve damage seems to occur in three-quarters of all patients undergoing coronary artery bypass graft-internal thoracic artery surgery. A significant minority may continue to experience bothersome chronic chest wall pain.     

Redo coronary artery bypass grafting using the patent left internal thoracic artery graft as an in flow with composite internal thoracic artery Y grafting; report of a case

In redo coronary artery bypass grafting (CABG), graft selection and revascularization methods are major problems. We experienced a redo-CABG with occluded previous vein grafts. These grafts were to the circumflex artery and right coronary artery. We conducted operation using cardiopulmonary bypass. We at this operation, chose right internal thoracic artery (RITA) as a conduit and anastomosed it to the side of functioning left internal thoracic artery (LITA) graft, and then diogonal branch, posterolateral branch, and atrioventricular branch were revascularized with the RITA. Post operative course was uneventful. Internal thoracic artery (ITA) is superior to vein graft and other arterial graft as to long term patency. We believe composite Y graft with the use of bilateral ITA can be one of the revascularization strategy in redo CABG.     

Assessment of internal thoracic artery grafts using duplex scanning]

In an effort to develop a noninvasive method to evaluate flow characteristics of the internal thoracic artery grafts (ITAG) after coronary artery bypass grafting, we performed duplex scanning of ITAGs of 51 patients who underwent bypass grafting. The ITAG was visualized with a duplex scanner of 7.5 MHz through the first or second left intercostal space. The visualization of the ITAG was adequate to make reliable measurements in 47 patients (92.2%). The diameter of the vessel, systolic peak velocity, and diastolic peak velocity were recorded, and systolic flow volume, diastolic flow volume, velocity ratio, flow volume ratio, and diastolic flow volume fraction were calculated. The velocity ratio, flow volume ratio, and diastolic flow volume fraction were markedly higher in the unstenotic subjects than in the stenotic subjects. In the group in which severe LAD stenosis were recognized preoperatively, both systolic and diastolic flow volumes were increased compared with moderately stenotic group. No differences in flow characteristics could be demonstrated between the subjects with old anterior myocardial infarction and without it. In 10 patients in whom flow pattern was abnormal or not identified, angiography revealed graft stenosis or predominant native coronary arterial flow. Duplex scanning is thought to be a reliable, sensitive, and noninvasive technique for the assessment of the ITAG.     

A quantitative study of postoperative luminal narrowing of the internal thoracic artery graft in coronary artery bypass surgery.

We used quantitative angiography to determine the postoperative diameter of the internal thoracic artery graft at the point close to the anastomosed site in 147 patients who received the graft for the left anterior descending coronary artery. We performed generalized multiple linear regression analysis (Type I quantification method) to assess the effects of the following factors on the internal thoracic artery graft diameter: age, gender, time of angiography, laterality of the internal thoracic artery used, presence of an undivided major side branch of the internal thoracic artery, presence of a saphenous vein graft having blood flow competition with an internal thoracic artery graft, presence of distal stenosis of the recipient left anterior descending coronary artery, severity of postoperative left anterior descending coronary artery stenosis, and presence of coronary risk factors. The standardized category scores for 25% left anterior descending coronary artery stenosis, 50% left anterior descending coronary artery stenosis, and presence of a saphenous vein graft having blood flow competition with an internal thoracic artery graft were -1.418, -0.767 and -0.622, respectively. Thus, the internal thoracic artery diameter was smaller in patients with well-preserved flow of the recipient coronary artery. The internal thoracic artery diameter had a particularly strong correlation with the degree of left anterior descending coronary artery stenosis (partial correlation coefficient: 0.670). The other factors seemed to have little or no correlation with the postoperative internal thoracic artery diameter. With the criterion that the internal thoracic artery diameter below 1.0 mm represents the "string sign" of internal thoracic artery graft, this phenomenon was observed in nine patients (6.1%). In all of these patients, left anterior descending coronary artery flow was well-preserved, and no ischemia was disclosed in the left anterior descending coronary artery-perfused area. These results indicate that internal thoracic artery grafts have flow adaptability responding to the flow demand of the recipient coronary artery and that the string sign of internal thoracic artery grafts is mainly an outcome of its physiologic characteristics.     

Midterm results of coronary artery bypass graft surgery with internal thoracic artery under low free-flow conditions

Background

We use the left internal thoracic artery (LITA) even when flow is very low. In this study, we investigated midterm outcome of coronary artery bypass graft surgery with low free-flow LITA.

Methods

One hundred patients undergoing coronary artery bypass graft surgery using LITA with a free flow of less than 20 mL/min were reviewed. The mean follow-up duration was 47.4 months, ranging from 1 to 65 months. Graft angiography was performed postoperatively. The diameter of the LITA was assessed angiographically. Cumulative graft patency, cardiac-related event-free rate, and actuarial survival rate were calculated by the Kaplan-Meier method.

Results

An early postoperative Doppler study showed that the diastolic-to-systolic ratio in the LITA was 1.76 ± 0.33. A 1-month postoperative angiography revealed LITA string sign in 2 patients. One had a percutaneous coronary intervention, whereas string sign was not detected in the second patient, and LITA patency showed a marked improvement in 1-year postoperative angiogram. One month postoperatively the LITA diameter was 1.6 ± 0.4 mm, and significantly enlarged in the second angiogram (1.9 ± 0.4 mm, p = 0.0003). There was a significant correlation between the diameter of the LITA and the left anterior descending coronary artery (r = 0.889, p = 0.0001). The cumulative graft patency rate at 1 and 4 years was 99.0% and 94.3%, respectively. The cardiac-related event-free rate at 1 and 5 years was 97.0% and 93.3%, respectively. The actuarial survival rate at 5 years was 97.1%.

Conclusions

Even with a very low LITA free flow, graft function improves with LITA growth, if there was no mechanical damage that impedes recovery.     

The internal mammary bypass graft: a superior second coronary artery.

In a study of the initial 1,004 consecutive patients who had direct coronary artery bypass at Ochsner Medical Institutions, computer methods of data processing were used to compare the clinical results between patients who had saphenous vein (SV) grafts and those who had internal mammary artery (IMA) grafts. The factors compared were the long-term mortality rates, nonfatal myocardial infarction rates, relief or persistence of angina, and the percentage of patients who acquired congestive heart failure. A simple comparison showed the patients with IMA grafts did better in all four categories; however, in a subsequent analysis in which maldistributed factors were removed, the rates of anginal relief and congestive heart failure were not significantly improved. The major benefit appears to be an increase in longevity among patients who had IMA bypasses.     

Right gastroepiploic artery as a coronary bypass graft

Between November 1987 and April 1988, the right gastroepiploic artery (GEA) was used as a coronary artery bypass graft in 11 patients, 9 men and 2 women. In 1 of them, the GEA was used because no veins were available; in the others, the GEA was used to avoid the use of vein grafts. The GEA was anastomosed to the right coronary artery in all patients, and internal mammary artery grafts were used to bypass the left anterior descending and circumflex coronary arteries. All patients survived the operation. There were no early and, to date, there have been no late complications of the abdominal component of the operation. Postoperative coronary angiography showed a patent right GEA in 9 patients (82%). In 1 patient the GEA was occluded, probably because of an enlarged liver. If the long-term patency of right GEA grafts is similar to that of internal mammary artery grafts, wider use of this viable graft is indicated.     

Thoracodorsal artery as a free graft for coronary artery bypass grafting.

Arterial myocardial revascularization using different arterial conduits as mammary, radial, gastroepiploic, subscapular and epigastric arteries are well documented. This report describes a preparation and use of thoracodorsal artery as a free graft for coronary artery bypass grafting. The preparation and removal of thoracodorsal artery were performed through right axilla. The artery was used as a free conduit for left anterior descending artery (LAD) in a 58-year-old female for the second revascularization. The saphenous veins, mammary arteries, right radial artery and epigastric artery were not available. The perioperative course was uneventful and we can recommend the graft as an alternative for such cases.