[Single versus bilateral internal thoracic artery grafts for multi vessel coronary artery bypass grafting: mid-term results]

BACKGROUND

The issue of superiority of single internal thoracic artery grafting versus bilateral internal thoracic artery grafting remains unresolved.

AIM

The aim of this study was to compare the early results and midterm outcome of single and bilateral internal thoracic artery grafting for multivessel coronary artery bypass grafting.

METHODS

Between January 2005 and March 2010, 196 patients underwent primary coronary artery bypass grafting with at least one internal thoracic artery grafts. Early results and Outcomes of patients undergoing single internal thoracic artery (SIMA) plus saphenous vein grafting (n=145) and bilateral internal thoracic artery (BIMA) plus saphenous vein grafting (n=51) were obtained at a mean followup of 29 months.

RESULTS

Patients with bilateral internal thoracic artery grafting were younger, had less hypertension, higher left main disease and better Euroscore than patients undergoing single internal thoracic artery grafting. In-hospital mortality was similar for the two groups: 6.9 % for patients undergoing SIMA versus 5.9 % for those undergoing BIMA (p=0.8). Sternal wound infection was also similar (2.8% versus 3.9% p=0.68). Mid-term mortality was (4% VS 4.8% p=0.71) and event free survival probability at 28 months was 75% for the single-graft group compared with 85.7% for the bilateral-graft group (P =0.46).

CONCLUSION

Our study found similar early and mid-term clinical outcomes for patients undergoing SIMA plus saphenous vein grafting and those undergoing BIMA plus saphenous vein grafting for multivessel coronary artery bypass grafting.

'No-touch' saphenous vein harvesting improves graft performance in patients undergoing coronary artery bypass surgery: a journey from bedside to bench

The saphenous vein is the most commonly used conduit in patients undergoing coronary artery bypass surgery yet its patency is inferior to the internal thoracic artery. Vascular damage inflicted to the vein when using conventional harvesting techniques affects its structure. Endothelial denudation is associated with early vein graft failure while damage of the outermost vessel layers has adverse long-term effects on graft performance. While many in vitro and in vivo experimental studies aimed at improving vein graft patency have been performed to date no significant 'bench to bedside' advances have been made. Among experimental strategies employed is the use of pharmacological agents, gene targeting and external stents. A 'no-touch' technique, where the saphenous vein is removed with minimal trauma and normal architecture preserved, produces a superior graft with long term patency comparable to the internal thoracic artery. Interestingly, many experimental studies are aimed at repairing or replacing those regions of the saphenous vein damaged when harvesting conventionally. 'No-touch' harvesting is superior in coronary artery bypass patients with long-term data published 5years ago. Here we describe a 'bedside to bench' situation where the mechanisms underlying the improved performance of 'no touch' saphenous vein grafts in patients have been studied in the laboratory.

Short-term complications after bilateral internal mammary artery grafting--a retrospective study

OBJECTIVES

To analyze our experience of conducting Bilateral Internal Mammary Artery (BIMA) grafting, using both pedicled and free grafts for coronary revascularization, assessing the safety and efficacy of the procedure and comparing any differences observed between the two techniques of harvesting the grafts.

METHODS

A retrospective cross sectional study was conducted in July 2010 in which all 48 patients undergoing bilateral internal mammary artery grafting for coronary bypass surgery at the Aga Khan University Hospital from 1996 to 2010 were reviewed and evaluated. The main outcome measures were perioperative mortality and early morbidity with particular reference to cerebrovascular accidents, sternal wound complications and re-opening for bleeding. Chi-square test was used to elicit any meaningful associations between patient characteristics and post-operative outcomes.

RESULTS

Of the 48 patients undergoing bilateral IMA grafting, 46 were males and 2 females. The mean age was 48 +/- 9.4 years. Dyslipidaemia and smoking were the most common identifiable risk factors for coronary vascular disease. Following the 40 elective and 8 emergent surgeries, there was one hospital death. The most common post-operative complications were arrhythmias and wound infection. Diabetes and obesity were not observed to be associated with an increased risk of developing surgical site infection.

CONCLUSIONS

Our study suggests that the short-term efficacy and the safety profile of bilateral IMA grafting for coronary revascularization is clinically acceptable. Long-term follow-up studies should be done to assess the cardiac event-free survival of these individuals evaluating its applicability as a routine for coronary artery bypass grafting in Pakistan.

Role of internal mammary artery bypass grafts in retrograde chronic total occlusion interventions

The role of internal mammary artery grafts in facilitating retrograde chronic total occlusion interventions is controversial. We describe two cases demonstrating: (a) retrograde wiring via a left internal mammary artery graft; and (b) using the left internal mammary graft for vessel visualization while retrograde crossing to the right coronary artery was achieved via the native left main coronary artery (triple arterial access). The internal mammary artery grafts can facilitate retrograde chronic total occlusion interventions, but should be used with caution to minimize the risk of injury.

How to use the left internal thoracic artery which has been damaged during harvesting?

The established superiority of the internal thoracic artery as a coronary arterial conduit has led to its mandatory use in coronary artery bypass grafting surgery. Therefore, the damage of the internal thoracic artery during harvesting is an abysmal complication, after which the conduit is usually discarded. An alternative approach is presented here, which has allowed us to use the distal two thirds of the proximally damaged left internal thoracic artery as an in situ (with retrograde blood supply from superior epigastric and musculophrenic arteries), reversed arterial conduit to revascularize the left anterior descending coronary artery.

Effect of the degree of LAD stenosis on "competitive flow" and flow field characteristics in LIMA-to-LAD bypass surgery

The long-term patency of the left internal mammary artery (LIMA) in left anterior descending (LAD) coronary stenosis bypass surgery is believed to be related to the degree of competitive flow between the LAD and LIMA. To investigate the effect of the LAD stenosis severity on this phenomenon and on haemodynamics in the LIMA and anastomosis region, a numerical LIMA-LAD model was developed based on 3D geometric (obtained from a cast) and hemodynamic data from an experimental pig study. Proximal LAD pressure was used as upstream boundary condition. The model counted 13 outlets (12 septal arteries and the distal LAD) where flow velocities were imposed in systole, while myocardial conductance was imposed in diastole via an implicit scheme. LAD stenoses of 100 (total occlusion), 90, 75 and 0 % area reduction were constructed. Low degree of LAD stenosis was associated with highly competitive flow and low wall shear stress (WSS) in the LIMA, an unfavourable hemodynamic regime which might contribute to WSS-related remodelling of the LIMA and suboptimal long-term LIMA bypass performance.

Are two internal thoracic artery grafts as safe as one? Experience from Green Lane Hospital

AIM

To compare short-term mortality and major morbidity between patients undergoing elective primary isolated CABG with bilateral internal thoracic artery (BITA) or single internal thoracic artery (SITA) grafts at Green Lane Hospital (Auckland, New Zealand).

METHODS

We conducted a retrospective study of short-term outcomes in 5955 patients receiving SITA and 637 patients receiving BITA grafts between 1990 and 2004. Only patients undergoing elective primary isolated coronary artery surgery were included. The primary outcome was a composite end-point (early death, perioperative MI, reoperation for sternal wound complications or significantly prolonged hospital stay). Patients receiving BITA grafts were case-matched with patients receiving SITA grafts for confounding factors and comparison was made between perioperative outcomes in the two groups.

RESULTS

After case-matching, no statistically significant difference was found in the incidence of our primary endpoint between patients receiving BITA versus SITA grafts [odds ratio 0.84 (95% CI 0.59, 1.21)]. Furthermore, there was no difference in rates of reoperation for sternal wound complications between the two groups [odds ratio 1.00 (95% CI 0.29, 3.44)].

CONCLUSIONS

Given the potential long-term clinical advantages of BITA grafting, our results support the increased use of BITA grafts in selected patients.

Anterograde flow compromise of a patent left internal mammary artery graft from a proximal subclavian artery stenosis. Myocardial ischemia not driven by the coronary-subclavian steal syndrome mechanism

A 54-year male with previous triple vessel coronary artery and aorto-bi-femoral bypass graft surgeries complained of crescent angina. Stress induced myocardial ischemia on echocardiography was demonstrated. We performed direct stenting of a saphenous vein graft to the right coronary artery, via right radial approach. Subsequently stenting of a severe left subclavian artery proximal stenosis was performed via right brachial approach in order to relieve an overt myocardial ischemia in the territory supplied by a patent left internal mammary artery graft originated distally to the left subclavian stenosis. The finding of a total left axillary artery occlusion complement the pathogenesis of myocardial ischemia produced by limited anterograde flow and not driven by the common flow reversal mechanism of a typical coronary-subclavian steal syndrome.

Sternal neoangiogenesis following internal mammary artery devascularization: an experimental model

AIM

The use of bilateral internal thoracic arteries (BIMA) for coronary artery revascularization is associated with better long-term survival and longer freedom from reoperation. Concerns of deep sternal wound infections and mediastinitis have constantly emerged with the utilization of BIMA grafts on a routine basis, especially in diabetic patients.

METHODS

We performed a quantitative evaluation of sternal bone healing and angiogenesis after left (LIMA) or bilateral internal mammary artery (BIMA) ligation two and four weeks after sternotomy in normal and diabetic Sprague-Dawley rats.

RESULTS

The BIMA group showed a significant increase in neoangiogenesis two weeks after surgery compared to LIMA and control groups (control: 38.3 ± 5.1 vessels/mm², LIMA: 31.4 ± 3.6 vessels/mm², BIMA: 81.6 ± 7.7 vessels/mm²; P=0.047 and P=0.04, respectively). Four weeks after the procedure, bilateral devascularization was associated with lower microvessel formation when compared to LIMA or control groups (control: 50.4 ± 5.2 vessels/mm², LIMA: 64.6 ± 4.9 vessels/mm²; BIMA: 31.5 ± 4.4 vessels/mm²; P=0.006 and P=0.02, respectively). Diabetic animals showed similar results with lower four weeks microvessel formation. However, there were no significant differences when animals with induced diabetes were compared to the normal euglycemic groups for each procedure performed.

CONCLUSION

BIMA ligation promotes an early increase in neoangiogenesis. Progressive sternal consolidation is associated with a significant lower level of capillaries and arterioles in the BIMA group four weeks after ligation. Diabetes did not influence the extent of neoangiogenesis between groups with similar procedures. More important clinical determinants could explain the increase incidence of sternal infection in this specific population.

Cell-free collagen-based scaffolds used for making blood vessels in cardiovascular surgery

The present article deals with the technology of obtaining decellularized cell-free collagen-based scaffolds from arterial vessels and surgical assessment of the possibility of experimentally implanting them into the blood system of laboratory animals for experimental purposes. The study was performed on arterial vessels (n=60) and fragments of the human internal thoracic artery (n=20). Described herein is a method of obtaining a connective-tissue matrix of a blood vessel by means of vessel's perfusion for 2-3 hours with detergent solutions. Cell-free collagen-based conduits were implanted to a total of ten dogs. After the operation, the blood flow remained functional. The anastomoses established turned out to be leak-proof and the acellular vessels were able to withstand the haemodynamic load of the arterial blood flow.

Atresia of the left internal mammary artery graft following percutaneous intervention of the left main

Because of its durability and patency, the left internal mammary artery (LIMA) is preferentially used to bypass obstructive lesions in the left main coronary artery (LMCA) and/or the left anterior descending coronary artery (LAD). The long-term patency of the LIMA graft is determined by several factors, principal among them being the dynamic competition between flow through the internal mammary artery graft and the LAD. We report a patient with LMCA stenosis and a well-functioning and mature LIMA graft, who after percutaneous intervention of the LMCA and normalized antegrade flow in the LAD, developed atresia of a large caliber LIMA graft.

Off-pump sequential bilateral internal mammary artery grafting combined with selective arterialization of the coronary venous system

BACKGROUND

Off-pump coronary artery bypass surgery (OPCAB) has been widely applied in recent years as a less invasive method of myocardial revascularization. This study evaluated the sequential bilateral internal mammary artery grafting combined with selective arterialization of the coronary venous system during OPCAB.

METHODS

From April 2004 to August 2010, patients with diffuse right coronary lesions were studied retrospectively and divided into two groups. Group 1 included seventeen patients who underwent this surgery while group 2 included twenty-one patients without right coronary artery surgical therapy. All patients presented with symptoms of angina. Blood flow of bridged vessels was measured. The perioperative ventricular parameters including left ventricular ejection fraction and end diastolic diameter were compared. During follow-up, myocardial nuclide imaging and coronary angiography were carried out.

RESULTS

Off-pump coronary artery bypass was performed with an average of 3.6 grafts per patient. Hospital mortality was zero. At the time of follow-up, the patients in group 1 recovered better than in group 2 (P < 0.05). In both groups, the mean New York Heart Association (NYHA) class and ejection fraction increased significantly (P < 0.001) and the mean left ventricular end-diastolic diameter decreased significantly (P < 0.05). Myocardial blood supply of inferior wall in group 1 was obviously improved by myocardial nuclide imaging. Coronary angiography for eight patients in group 1 verified that there was blood flow to myocardium in the arterialized vein.

CONCLUSIONS

Sequential bilateral internal mammary artery grafting combined with selective arterialization of the coronary venous system can be performed during OPCAB. A postoperative improvement in the cardiac functions and the quality of life was documented, increasing our expectation for extensive application.

The internal mammary artery perforator (IMAP) breast-flap harvested from an asymmetric hyperplastic breast for correction of a mild funnel chest deformity

Pectus excavatum deformity is the most frequent congenital anomaly of the thoracic wall. If the invasive surgical procedures of thoracoplasty are not indicated or the patient refuses them, alternative treatment options should be considered. In such cases, local or distant transposition of autologous tissue could be appropriate. This report presents a selected case of funnel chest deformity and concomitant unilateral breast hyperplasia. Both deformities were corrected simultaneously using a pedicled internal mammary artery perforator (IMAP) flap dissected from the hyperplastic breast. This is a safe, reliable, low-morbidity, one-stage option for adult women that uses an easy-to-harvest flap for simultaneous correction of mild funnel chest deformity and concomitant breast hyperplasia with a single resulting scar.

Occlusion of a left internal mammary artery graft side branch during attempts to deliver an amplatzer vascular plug

We present a case of angina in a patient with a left internal mammary artery graft that had a large side branch. Closure was attempted using an Amplatzer vascular plug but during attempts to position the device, the side-branch occluded, likely due to dissection, obviating the need for device deployment.

Collateralization of an occluded left internal mammary artery coronary bypass graft

The left internal mammary artery (LIMA) is frequently utilized in coronary artery bypass grafting (CABG); adequate visualization of the LIMA bypass graft during diagnostic angiography is critical for determination of myocardial blood supply. We present a novel case of angiography via a left transradial approach demonstrating an occluded LIMA coronary bypass graft with antegrade flow maintained via a collateral branch from the ipsilateral thyrocervical trunk. Given the prevalence of LIMA use in CABG, it is critical to be aware of unusual configurations, including collateralization of a proximally occluded LIMA graft as described in this report.

Patency of internal thoracic artery and vein grafts according to revascularized coronary artery properties

Long-term results of surgical myocardial revascularization are determined by the quality of grafts and the progression of atherosclerosis in coronary arteries. The aim of the study was to evaluate the patency rate of internal thoracic artery and great saphenous vein grafts in relation to the hemodynamic properties of revascularized coronary artery. The patency of internal thoracic artery and great saphenous vein grafts was analyzed in relation to the degree of coronary stenosis estimated by angiography and the diameter of distal portion of coronary artery assessed intra-operatively. The long-term patency of great saphenous grafts depends on the distal coronary artery diameter but not on the degree of coronary artery stenosis. The patency of internal thoracic artery graft depends on the degree of coronary artery stenosis but not on the distal coronary artery diameter. The internal thoracic artery is the superior graft in coronary surgery, but the low patency rate in case of moderate coronary artery stenosis emphasizes the importance of selective approach.