Does skeletonization compromise the integrity of internal thoracic artery grafts?

Up-to-Date, Skeletonized or Pedicle Bilateral Internal Mammary Artery; Does It Matter?

PURPOSE

In this article, we reported on the up-to-date literature regarding skeletonized bilateral internal mammary artery (BIMA) flow and the effect on sternal perfusion. We also reviewed the pros and cons of the skeletonization technique versus the conventional pedicle technique for harvesting the BIMA.

METHODS

We performed an up-to-date review using the PubMed database, with a specific focus on the contemporary published literature.

RESULTS

BIMA skeletonization can preserve the sternal microcirculation, minimize tissue damage, and maintain blood supply to the chest wall at the tissue level. This effect is also apparent in diabetics. Deep sternal wound infection (DSWI) rates are significantly less with skeletonization versus the conventional pedicle technique and are comparable to single internal mammary artery harvesting.

CONCLUSIONS

Contemporary large-scale studies demonstrate that skeletonization of the BIMA increases conduit length, provides superior flow, reduces the incidence of DSWIs, and improves late survival. Hopefully, this review will increase awareness of the compelling evidence in favor of using skeletonized internal mammary arteries and stimulate increased uptake of BIMA revascularization surgery.

A non-conventional proximal inflow for the radial artery coronary graft

Despite good outcomes, the use of the radial artery as a coronary graft is not widespread. Concerns regarding its low versatility and the risk of hand ischaemia, as well as the lack of reliable information regarding the best storage solution of the graft, and regarding the treatment for preventing spasms have limited its use. In this manuscript, the (numerous) benefits and (few) drawbacks of the proximal inflow for the radial artery from the in situ right internal thoracic artery proximal stump are discussed. Outcomes are reported from a limited series of patients undergoing totally arterial myocardial revascularization using this composite graft and both internal thoracic arteries.

Clinical Validation of a Coronary Surgery Technique That Minimizes Aortic Manipulation

BACKGROUND

To minimize aortic manipulation and maximize use of arterial conduits are aims of modern coronary surgery.

METHODS

From March 2012 to October 2016, 890 consecutive patients with multivessel coronary disease underwent isolated coronary operations using both internal thoracic arteries (ITAs). In 205 (23%; mean age, 67.6 ± 9.2 years), the right ITA was proximally transected and used as a free graft, while its in situ stump was elongated with a saphenous vein graft. The new arteriovenous I conduit was directed to the inferolateral cardiac wall. Operative data and early outcomes of these patients (I group) were compared with the remaining 685 patients (control [C] group). Early and late outcomes were also compared in 184 pairs identified with propensity score matching.

RESULTS

Between the I and C groups there was no significant difference in expected operative risk (European System for Cardiac Operative Risk Evaluation II, p = 0.28), although diseased ascending aorta (p < 0.0001) and critical preoperative state (p = 0.027) were more frequent in the I group. Despite a higher number of coronary anastomoses (mean, 4 ± 0.9 vs 3.7 ± 1, p < 0.0001), cardiopulmonary bypass time was shorter in the I group both in overall (86.7 ± 23.7 vs 105.7 ± 34.2 minutes, p < 0.0001) and matched series (86.8 ± 24.1 vs 108.8 ± 31.9 minutes, p < 0.0001). In-hospital mortality (1% vs 1.9%, p = 0.54) and the rates of postoperative complications were similar. During the follow-up period, no intergroup difference was found in matched patients in the nonparametric estimates of freedom from all-cause death (p = 0.39) and major adverse cardiac and cerebrovascular events (p = 0.44).

CONCLUSIONS

Surgery using this arteriovenous I conduit is safe, minimizes aortic manipulation, shortens cardiopulmonary bypass time, and aids complete revascularization.

An innovative panel to assess endothelial integrity of pedicled and skeletonized internal thoracic artery used as aortocoronary bypass graft: a randomized comparative histologic and immunohistochemical study

Background

Optimal preservation of endothelial integrity of the vessels used as aortocoronary grafts is a crucial determinant of long-term clinical success of coronary artery bypass grafting (CABG). The purpose of this study was to evaluate an impact of two common techniques to harvest left internal thoracic artery (LITA) on endothelial integrity.

Methods

One hundred twenty consecutive patients (84 males and 36 females) with a mean age of 64.9±8.8 years undergoing CABG were randomized to receive pedicled (group P; n=60) or skeletonized (group S; n=60) LITA grafts. During surgery LITA was harvested by the same experienced cardiac surgeon. The most peripheral surplus segments of LITA were obtained and then analysed histologically under light microscope. Additionally, endothelial expression of CD31, CD34, CD133 and nitric oxide synthase (eNOS) were evaluated by means of immunohistochemistry.

Results

In both groups, no cases of major arterial wall damage such as disruption, dissection, thrombosis or subadventitial hematoma were noted on LITA cross sections. Immunohistochemical assessment of protein expression revealed no differences in endothelial expression of CD133, CD34 antigens (markers of regeneration potential) and eNOS (indicating preserved functional integrity) between studied groups. Contrary to them, endothelial immunoreactivity of CD31, a marker of the morphological integrity of the endothelium, was revealed to be stronger in group P.

Conclusions

The skeletonized method of LITA harvesting may be associated with worse preservation of morphological integrity of endothelium but without compromising functional integrity and potential for tissue regeneration.

Liberal bilateral internal thoracic artery use in people with diabetes neutralizes the negative impact of insulin-requiring status

AIMS

Bilateral internal thoracic artery (BITA) grafts are underused in insulin-dependent diabetic patients because of increased risk of postoperative complications. The impact of the insulin-requiring status on outcomes after routine BITA grafting was investigated in this retrospective study.

METHODS

Skeletonized BITA grafts were used in 3228 (71.6%) of 4508 consecutive patients having multivessel coronary disease who underwent isolated coronary bypass surgery at the authors' institution from January 1999 to August 2015. Among these BITA patients, diabetes mellitus and the insulin-requiring status were present in 972 (30.1%) and 237 (7.3%) cases, respectively. After the one-to-one propensity score-matching, 215 pairs of insulin-dependent/noninsulin-dependent people with diabetes were compared as the postoperative outcomes. The operative risk was calculated for each patient according to the logistic European System for Cardiac Operative Risk Evaluation (logistic EuroSCORE).

RESULTS

As expected, insulin-dependent people with diabetes had higher risk profiles than noninsulin-dependent people with diabetes (median logistic EuroSCORE, 4.1 vs. 3.5%, P = 0.086). However, there were no differences in in-hospital mortality both in unmatched and propensity score-matched series (2.5 vs. 2%, P = 0.65 and 2.8 vs. 1.9%, P = 0.52, respectively). In propensity score-matched pairs, only prolonged invasive ventilation (P = 0.0039) and deep sternal wound infection (P = 0.071) were more frequent in insulin-dependent people with diabetes. No differences were found as the late outcomes.

CONCLUSION

In diabetic patients, the insulin-requiring status is by itself a risk factor neither for in-hospital death nor for poor late outcomes after routine BITA grafting. Only the risk of prolonged invasive ventilation and deep sternal wound infection are increased early after surgery.

Two questions on bilateral internal mammary artery usage

The use of a single internal mammary graft to the left anterior descending artery has been the gold standard in surgical coronary revascularization since its introduction. However, the take-up rate of use of bilateral internal mammary arteries has been slow despite emerging evidence. This has been partly due to the worry of postoperative complications, in particular, sternal wound complications. Skeletonization of the internal mammary has been proposed as a technique that can preserve the sternal microcirculation and therefore reduce this complication. In this article, we examine the evidence comparing the skeletonization technique versus the conventional pedicled technique for harvesting the internal mammary artery.

Randomized flow capacity comparison of skeletonized and pedicled left internal mammary artery

BACKGROUND

The preferential harvesting technique of the internal mammary artery has been periodically debated. This randomized study evaluated the flow outcome of the skeletonized versus pedicled left internal mammary artery.

METHODS

Two hundred patients undergoing surgery for left anterior descending coronary artery revascularization were enrolled and randomized to pedicled (n=100) or skeletonized (n=100) harvesting. Intraoperative baseline flow and post adenosine infusion into the left ventricle, hospital outcome, echocardiographic results, and troponin I leakage were analyzed. Noninvasive periodic evaluation of flow was carried out at rest and during intravenous adenosine infusion by transthoracic Doppler ultrasound, and was stratified according to the harvesting technique. Final angiographic evaluation was performed by 64-slice multidetector computed tomography.

RESULTS

Skeletonized left internal mammary arteries demonstrated better flow capacity at rest and during adenosine recruitment perioperatively and at all time points of follow-up. Troponin I leakage was significantly higher in the pedicled group (59 vs 42, p=0.02). Pedicled harvesting (hazard ratio [HR] 3.6, 95% confidence interval [CI] 2.5 to 6.9, p<0.001); indexed left ventricular mass greater than 150 g/m2 (HR 4.6, 95% CI 3.1 to 7.5, p<0.001); and baseline corrected thrombolysis in myocardial infarction frame count greater than 30 (HR 4.4, 95% CI, 3.8 to 7.2, p<0.001) were the most powerful multivariable predictors of graft flow reserve less than 2.0. Postoperative echocardiographic results and clinical and angiographic outcomes were comparable between the two groups.

CONCLUSIONS

Skeletonization of the left internal mammary artery, beyond traditional proven advantages, provided significantly higher flow capacity and better graft flow reserve.

Usefulness of an ultrasonic scalpel to harvest and skeletonize the superficial temporal artery for extracranial-intracranial bypass surgery

OBJECTIVE

A new method to harvest and skeletonize the superficial temporal artery (STA) using an ultrasonic scalpel is presented. The technique is simple and safe, and reduces bleeding. We also investigated histopathological changes in donor vessels and whether it is possible to shorten the time needed for STA harvesting using the ultrasonic scalpel.

METHODS

Between January 1, 2005, and December 31, 2007, 31 consecutive patients underwent STA and middle cerebral artery anastomosis surgery in our hospital. All patients underwent harvesting of both the frontal and parietal branches of the STA. STA harvesting using an ultrasonic scalpel was performed in 18 of the 31 patients. We compared the time needed for STA harvesting by dividing patients into 2 groups: a non-ultrasonic scalpel group and an ultrasonic scalpel group. We also examined the histopathological changes by application of ultrasonic waves on the STA in the 6 most recent patients.

RESULTS

The mean time needed for STA harvesting was 84.2 +/- 14.1 minutes for the non-ultrasonic scalpel group and 55.1 +/- 15.2 minutes for the ultrasonic scalpel group. The ultrasonic scalpel group showed a significantly shorter harvesting time than the non-ultrasonic scalpel group (P < 0.01). No histopathological change was observed in any layers of the STA.

CONCLUSION

Our data suggest that STA harvesting with the ultrasonic scalpel may be useful for STA-middle cerebral artery anastomosis surgery.

Skeletonization of radial and gastroepiploic conduits in coronary artery bypass surgery

The use of a skeletonized internal thoracic artery in coronary artery bypass graft surgery has been shown to confer certain advantages over a traditional pedicled technique, particularly in certain patient groups. Recent reports indicate that radial and gastroepiploic arteries can also be harvested using a skeletonized technique. The aim of this study is to systematically review the available evidence regarding the use of skeletonized radial and gastroepiploic arteries within coronary artery bypass surgery, focusing specifically on it's effect on conduit length and flow, levels of endothelial damage, graft patency and clinical outcome. Four electronic databases were systematically searched for studies reporting the utilisation of the skeletonization technique within coronary revascularisation surgery in humans. Reference lists of all identified studies were checked for any missing publications. There appears to be some evidence that skeletonization may improve angiographic patency, when compared with pedicled vessels in the short to mid-term. We have found no suggestion of increased complication rates or increased operating time. Skeletonization may increase the length of the conduit, and the number of sequential graft sites, but no clear clinical benefits are apparent. Our study suggests that there is not enough high quality or consistent evidence to currently advocate the application of this technique to radial or gastroepiploic conduits ahead of a traditional pedicled technique.

Intraoperative and Histochemical Comparison of the Skeletonized and Pedicled Internal Thoracic Artery

BACKGROUND

Skeletonization of the internal thoracic artery (ITA) has advantages, but the variation of ITA preparation may be traumatic for the arterial wall. We sought to compare intraoperative results and endothelial nitric oxide synthase (e-NOS) expression on the vessel wall after left ITA harvesting with skeletonization and the conventional technique.

METHODS

A prospective evaluation of 84 consecutive patients undergoing coronary artery bypass grafting was performed: 40 patients with skeletonized and 44 patients with pedicled left ITA. The lengths of ITA and free ITA blood flow were measured. Distal ITA segments were analyzed histopathologically and stained by antibodies against e-NOS.

RESULTS

In the skeletonized group, the length of the ITA were significantly longer than in the pedicled group (15.7 +/- 0.4 cm versus 19.0 +/- 0.6 cm; P = .001). Also, the free-flow capacity of the ITA was significantly higher than in the pedicled group (62.4 +/- 4.8 mL/min versus 88.6 +/- 6.9 mL/min; P = .001). e-NOS expressions on endothelial cells were similar between the groups. Dense e-NOS immunostaining was observed in vaso vasorum of the adventitia in the pedicled group. However, there was not any e-NOS immunostaining in vaso vasorum of the adventitia in the skeletonized group.

CONCLUSIONS

Although skeletonization of the ITA is a more technically demanding procedure, it provides some advantages such as increased available graft length and reduced sternal devascularization. This technique did not have any detrimental effects on the endothelial cell lining and e-NOS expressions on the endothelial layer. To reach a definitive judgment for using skeletonized ITA, we need information about the long-term angiographic patency rates.

Cardiovascular tissue engineering: state of the art

In patients requiring coronary or peripheral vascular bypass procedures, autogenous arterial or vein grafts remain as the conduit of choice even in the case of redo patients. It is in this class of redo patients that often natural tissue of suitable quality becomes unavailable; so that prosthetic material is then used. Prosthetic grafts are liable to fail due to graft occlusion caused by surface thrombogenicity and lack of elasticity. To prevent this, seeding of the graft lumen with endothelial cells has been undertaken and recent clinical studies have evidenced patency rates approaching reasonable vein grafts. Recent advances have also looked at developing a completely artificial biological graft engineered from the patient's cells with surface and viscoelastic properties similar to autogenous vessels. This review encompasses both endothelialisation of grafts and the construction of biological cardiovascular conduits.

Internal Thoracic Artery: To Skeletonize or Not to Skeletonize?

The internal thoracic artery has been the most reliable graft material used in coronary artery bypass grafting with an excellent long-term patency rate. Complete myocardial revascularization with internal thoracic arteries improves long-term survival and decreases the rate of repeat operations compared with vein grafts. Adequate length of the graft in coronary artery bypass graft surgery is essential for providing complete arterial revascularization. In the last decade or so, technique of skeletonization of internal thoracic artery has been proposed to achieve extra length. Skeletonization of the internal thoracic artery allows the preparation of longer conduits with a superior free flow and can reduce the incidence of postoperative pulmonary and sternal complications. However, concerns about vasoreactivity of skeletonized internal thoracic artery grafts, the functional consequences of surgical trauma, the possible loss of innervation, and vasa vasorum perfusion in the skeletonized conduits have prevented this technique from being universally accepted. Presently available evidence from retrospective studies (level 3 evidence) suggests that skeletonization is a safe and effective technique for myocardial revascularization. However, there is a need for conducting multicenter, randomized controlled trials comparing the skeletonized and pedicled internal thoracic arteries with special emphasis on long-term patency to conclusively validate the safety and efficacy of skeletonization technique.

Sternal Nourishment in Various Conditions of Vascularization

BACKGROUND

Early changes in sternal perfusion were studied after midline sternotomy and different methods of mammary artery (MA) harvesting.

METHODS

Our observations were made in the swine model after midline sternotomy. In group 1 (6 animals), after unilateral skeletonized MA harvesting, (99m)Tc particles were injected intravenously. In group 2 (7 animals), after unilateral mammary artery and vein harvesting (semiskeletonized technique), (99m)Tc particles were injected intravenously. In group 3 (5 animals), after skeletonized bilateral MA harvesting, 99mTc particles were injected into the intercostal musculature lateral to the sternal border. In groups 1 to 3, sternal samples were analyzed using gamma counting. In group 4 (6 animals), unilateral skeletonized MA harvesting was performed. In group 5 (5 animals), the MA was harvested unilaterally using the semiskeletonized technique. In groups 4 and 5, sternal blood flow was assessed using thermography. Data were collected in all groups for 5 hours postoperatively.

RESULTS

Both radioactive and thermographic flow measurements showed a statistically significant decrease in sternal blood flow on the side of harvested mammary vessels, regardless of harvesting technique. Radioactivity of the devascularized hemisterni on the side of intramuscular particle injection was substantially higher than in the contralateral half, confirming the role of diffusion in sternal nourishment. The distal sternal segments were least perfused by the MA.

CONCLUSIONS

There is an acute reduction of sternal perfusion during the early postoperative period, even if collaterals are preserved by skeletonized MA harvesting. Diffusion plays an important role in sternal nourishment, particularly of the xiphoid, and even more so after MA harvesting.

[In situ pedicle graft and coronary-coronary bypass grafting using internal thoracic artery in management of multiple lesions of the left anterior descending coronary artery]

INTRODUCTION

Nowadays, coronary-coronary bypass grafting (CCBG) has been applied in patients with heavily calcified ascending aorta or due to lack of graft material.

CASE REPORT

We describe a case in which the patient's large left anterior descending (LAD) coronary artery, running well over the cardiac apex, presented with proximal and distal stenosis. Although the pedicled left internal thoracic artery (ITA) graft is sometimes too short for sequential bypass in cases of distal stenosis of the LAD coronary artery, we used a free, short segment of the pedicled left ITA for coronary-coronary bypass grafting. The in situ remnant of the left pedicled ITA was used to bypass the proximal LAD stenosis. The patient's postoperative course was uneventful. Predischarge angiogram (on the 9th postoperative day) showed an in situ left ITA graft as well as afree coronarycoronary ITA graft. The patient had a regularfollow-up after 3 months, and was classified as New York Heart Association (NYHA) class I.

DISCUSSION

Primarily used in aorto-coronary bypass surgery (termino-terminal interposition of the saphenous vein between two parts of a resected coronary artery), CCBG was revised latter on, and from hemodynamic point of view the physiologic restoration of coronary blood flow has been confirmed CCBG might be an attractive approach for bypassing distal lesions of large coronary arteries (combined with arterial or venous grafting of targeted arteries, if proximal stenoses are also present). The proximal remnant of ITA can be used as an in situ or free graft.

Skeletonized Radial Artery Grafting: One-Year Patency Rate

BACKGROUND

The skeletonized radial artery harvesting technique has routinely been used in our institute. Its clinical outcome is acceptable; however, the graft patency rate at 1 year has not been reported.

METHODS

Between July 1, 2003, and October 31, 2002, 50 consecutive patients underwent isolated coronary artery bypass using skeletonized radial artery grafts in our hospital. There were no hospital deaths or perioperative myocardial infarctions. All patients completed follow-up by November 2003. Twenty of these patients (18 asymptomatic volunteers and 2 symptomatic patients) underwent coronary angiography at 1 year, and the results were analyzed.

RESULTS

At a mean (+/-SD) follow-up period of 1.2 +/- 0.2 years, there were no deaths. Two patients developed angina due to graft occlusion (1 in the radial artery and another in the gastroepiploic artery). Twenty-one radial artery grafts and 36 distal anastomoses with radial artery grafts were evaluated by angiography at 1 year (0.9 +/- 0.1 years). There was 1 radial artery graft occlusion affecting 1 distal anastomosis, giving a perfect graft patency rate of 95.2% (20/21) and a perfect anastomosis patency rate of 97.2% (35/36). The patient with the occluded radial artery graft had a history of peripheral vascular disease and diabetes. There were no graft stenoses or string signs.

CONCLUSION

At our limited follow-up, the results of using skeletonized radial artery grafts are excellent. Extensive skeletonization will not affect the graft patency rate or early graft spasm. Careful examinations of the radial artery grafts in patients with a history of peripheral artery disease and diabetes are mandated.

Should the internal thoracic artery be skeletonized?

Traditionally, the internal thoracic artery is harvested as a pedicle. In contemporary cardiac surgical practice, however, certain surgeons practice the internal thoracic artery-skeletonization technique. A systematic review of clinical studies reporting on the use of skeletonized internal thoracic arteries (SKT-ITA) has not yet been performed. The primary aim of this review article is to examine comprehensively the entire body of evidence regarding the use of SKT-ITA. In particular, we aimed to analyze the effects of skeletonization on sternal blood supply, wall damage and blood flow in the harvested vessel, postoperative graft patency, and clinical outcome. Advantages and disadvantages of the skeletonization technique are highlighted and discussed.

Skeletonized Gastroepiploic Artery for Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

Skeletonized arterial grafting may reduce the risk of graft spasm and may improve graft patency. Previously we reported a pilot study of skeletonized gastroepiploic artery (GEA) grafting with favorable results. Skeletonized GEA harvesting with an ultrasonic scalpel has now become our routine procedure. In this report, we compare the early clinical outcomes of skeletonized versus pedicled GEA grafting to assess the safety and benefit of use of skeletonized GEA in coronary artery bypass grafting.

METHODS

Between July 2002 and October 2003, the GEA was used as a conduit for isolated off-pump coronary artery bypass grafting in 105 patients. Of these, 21 patients (group P) received pedicled GEA and 59 patients (group S) received skeletonized GEA grafts (excluding 25 patients whose results were reported in the pilot study). The perioperative and early follow-up data were prospectively collected and compared.

RESULTS

No graft injury was found in either group. The preoperative characteristics were similar in the two groups except that group S had a smaller body surface area (1.64 +/- 0.16 m 2 in group S versus 1.73 +/- 0.16 m 2 in group P, P <.05) and a significant number of patients with diabetes (36/59, 61.0% versus 7/21, 33.3%, P <.05). The number of distal anastomoses was 4.3 < 1.0 versus 3.9 +/- 0.9 ( P = not significant [NS]). An in situ GEA composite graft was constructed in 8 (13.6%) of the patients in group S and none of the patients in group P ( P = NS). There was one hospital death due to infection in group S. Otherwise, there were no cases of low output syndrome or postoperative myocardial infarction in either group. During early postoperative follow-up, no angina recurrence or myocardial infarction was found.

CONCLUSION

The GEA can be skeletonized safely with an ultrasonic scalpel. Skeletonization enables a wider variety of choices in the use of GEA grafting.