Implantation in coronary circulation induces morphofunctional transformation of radial grafts from muscular to elastomuscular

Clinical and financial outcomes associated with the utilization of right internal mammary artery versus radial artery in multivessel coronary artery bypass grafting

BACKGROUND

Multi-arterial coronary bypass grafting with the left internal mammary artery as a conduit has been shown to offer superior long-term survival compared to single-arterial coronary bypass grafting. Nevertheless, the selection of a secondary conduit between the right internal mammary artery and the radial artery remains controversial. Using a national cohort, we examined the relationships between the right internal mammary artery and the radial artery with acute clinical and financial outcomes.

METHODS

Adults undergoing on-pump multivessel coronary bypass grafting with left internal mammary artery as the first arterial conduit were identified in the 2016 to 2020 Nationwide Readmissions Database. Patients receiving either the right internal mammary artery or the radial artery, but not both, were included in the analysis. Multivariable regression models were fitted to examine the association between the conduits and in-hospital mortality, as well as additional secondary outcomes.

RESULTS

Of an estimated 49,798 patients undergoing multi-arterial coronary bypass grafting, 29,729 (59.7%) comprised the radial artery cohort. During the study period, the proportion of multi-arterial coronary bypass grafting utilizing the radial artery increased from 51.3% to 65.2% (nptrend <0.001). Following adjustment, the radial artery was associated with reduced odds of in-hospital mortality (adjusted odds ratio 0.44), prolonged mechanical ventilation (adjusted odds ratio 0.78), infectious complications (adjusted odds ratio 0.69), and 30-day nonelective readmission (adjusted odds ratio 0.77, all P < .05).

CONCLUSION

Despite no definite endorsement from surgical societies, the radial artery is increasingly utilized as a secondary conduit in multi-arterial coronary bypass grafting. Compared to the right internal mammary artery, the radial artery was associated with lower odds of in-hospital mortality, complications, and reduced healthcare expenditures. These results suggest that whenever feasible, the radial artery should be the favored conduit over the right internal mammary artery. Nevertheless, future studies examining long-term outcomes associated with these vessels remain necessary.

Long-term observational angiographic patency and perfect patency of radial artery compared with saphenous vein or internal mammary artery in coronary bypass surgery

OBJECTIVES

It is uncertain if the long-term biological behavior of the radial artery as a conduit for coronary bypass surgery has a similar resistance to the development of atherosclerosis as for the internal mammary artery. We aimed to examine long-term angiographic patency and disease-free patency (perfect patency) for internal mammary artery, radial artery, and saphenous vein grafts.

METHODS

A retrospective, single-center, individual patient cohort study of angiographic observations from patients' latest postoperative angiogram from 1997 to 2020 was performed. Analysis was per anastomosis and assessed for patency and perfect patency. A generalized linear mixed model premised upon logistic regression was used to minimize confounding bias.

RESULTS

A total of 983 patients with 3064 grafts were included, with a median follow-up of 8.6 (interquartile range, 4.4-12.6) years after the operation. Multivariable analysis revealed differences for radial (patency, 86.9%; perfect patency, 86.4%) and internal mammary artery (patency, 93.9%; perfect patency, 93.5%) versus saphenous vein graft (patency, 72.8%; perfect patency, 46.2%). There were no differences between the 2 arterial conduits for patency (odds ratio, 1.40; 95% CI, 0.85-2.33; P = .189) and perfect patency (odds ratio, 1.14; 95% CI, 0.71-1.84; P = .578). If a conduit was patent, then 99.4% of radial artery, 99.6% of internal mammary artery, and 63.5% of saphenous vein graft were reported as perfectly patent.

CONCLUSIONS

Radial artery and internal mammary artery had similar patency and perfect patency while both were superior to saphenous vein graft.

Diagnostic radiology methods for assessing coronary artery bypass graft viability

The review describes available modern radiological methods which are currently applied for a detailed and comprehensive anatomical and functional assessment of the viability of various coronary artery bypass grafts. In addition, it presents some aspects of the implementation of these methods and clinical interpretation of the results.

Radial artery versus saphenous vein versus right internal thoracic artery for coronary artery bypass grafting

OBJECTIVES

We used individual patient data from 4 of the largest contemporary coronary bypass surgery trials to evaluate differences in long-term outcomes when radial artery (RA), right internal thoracic artery (RITA) or saphenous vein graft (SVG) are used to complement the left internal thoracic artery-to-left anterior descending graft.

METHODS

Primary outcome was all-cause mortality. Secondary outcome was a composite of major adverse cardiac and cerebrovascular events (all-cause mortality, myocardial infarction and stroke). Propensity score matching and Cox regression were used to reduce the effect of treatment selection bias and confounders.

RESULTS

A total of 10 256 patients (1510 RITA; 1385 RA; 7361 SVG) were included. The matched population consisted of 1776 propensity score-matched triplets. The mean follow-up was 7.9 ± 0.1, 7.8 ± 0.1 and 7.8 ± 0.1 years in the RITA, RA and SVG cohorts respectively. All-cause mortality was significantly lower in the RA versus the SVG [hazard ratio (HR) 0.62, 95% confidence interval (CI): 0.51-0.76, P = 0.003] and the RITA group (HR 0.59, 95% CI 0.48-0.71, P = 0.001). Major adverse cardiac and cerebrovascular event rate was also lower in the RA group versus the SVG (HR 0.78, 95% CI 0.67-0.90, P = 0.04) and the RITA group (HR 0.75, 95% CI 0.65-0.86, P = 0.02). Results were consistent in the Cox-adjusted analysis and solid to hidden confounders.

CONCLUSIONS

In this pooled analysis of 4 large coronary bypass surgery trials, the use of the RA was associated with better clinical outcomes when compared to SVG and RITA.

Radial artery or saphenous vein for Coronary artery bypass grafitng

Coronary artery disease (CAD) is the most common cardiovascular disease worldwide, affecting over 18 million American adults. Coronary artery bypass grafting (CABG) is the standard of care for patients with left main or triple vessel CAD. Historically, the saphenous vein (SV) has been utilized to bypass the majority of the coronary vessels in patients undergoing CABG, but more recent data suggest that the use of the radial artery (RA), rather than the SV, is associated with improved cardiac outcomes and better survival. The aim of this review is to summarize the current literature on the use of RA and SV for CABG in patients with multivessel CAD.

Effect of Calcium-Channel Blocker Therapy on Radial Artery Grafts After Coronary Bypass Surgery

BACKGROUND

Few studies have evaluated the effect of chronic calcium-channel blocker therapy (CCB) on the angiographic and clinical outcome of radial artery (RA) grafts used for coronary bypass surgery.

OBJECTIVES

The purpose of this study was to evaluate if CCB influences midterm clinical and angiographic outcomes of RA grafts.

METHODS

Patient-level data of 6 angiographic randomized trials evaluating RA graft status at midterm follow-up were joined in this observational analysis. Cox regression and propensity score methods were used to evaluate the effect of CCB on the incidence of a composite of major adverse cardiac events (MACE) (death, myocardial infarction, and repeat revascularization) and graft occlusion.

RESULTS

The study population included 732 patients (502 on CCB). The median clinical follow-up was 60 months. The cumulative incidence of MACE at 36, 72, and 108 months was 3.7% vs. 9.3%, 13.4% vs. 17.6%, and 16.8% vs. 20.5% in the CCB and no CCB groups, respectively (log-rank p = 0.003). Protocol-driven angiographic follow-up was available in 243 patients in the CCB group and 200 in the no CCB group. The median angiographic follow-up was 55 months. The cumulative incidence of RA occlusion at 36, 72, and 108 months was 0.9% vs. 8.6%, 9.6% vs. 21.4%, and 14.3% vs. 38.9% in the CCB and no CCB groups, respectively (log-rank p < 0.001). After controlling for known confounding, CCB therapy was found to be consistently associated with a significantly lower risk of MACE (multivariate Cox hazard ratio: 0.52; 95% confidence interval: 0.31 to 0.89; p = 0.02) and RA graft occlusion (multivariate Cox hazard ratio: 0.20; 95% confidence interval: 0.08 to 0.49; p < 0.001).

CONCLUSIONS

In patients with RA grafts CCB is associated with significantly better midterm clinical and angiographic RA outcomes.

Right internal thoracic or radial artery as the second arterial conduit for coronary artery bypass surgery

PURPOSE OF REVIEW

To summarize the available evidence on the use of the right internal thoracic artery (RITA) and the radial artery as the second arterial graft in coronary artery bypass surgery.

RECENT FINDINGS

The current data support the equipoise of the two conduits in terms of clinical and angiographic outcomes. Both RITA and radial artery have better patency than saphenous vein grafts. The use of the RITA carries an increased risk of deep sternal wound infection (DSWI) if the artery is harvested as pedicle. Bilateral internal thoracic artery grafting is more technically demanding than radial artery use and there is a volume-outcome relationship in terms of mortality and incidence of DSWI. The radial artery is preferable over RITA in right-sided or distal circumflex artery targets with high-degree stenosis and in patients at higher risk for DSWI, whereas it is not recommended to graft vessels with moderate stenosis and in cases of insufficient collateralization from the ulnar artery or previous transradial procedures.

SUMMARY

The patency rate and clinical outcomes of radial artery and RITA are similar. The use of one or the other should be based on a careful evaluation of the patient's coronary anatomy and comorbidities, the conduit availability and the surgeon's and center's experience.

Technical Aspects of the Use of the Radial Artery in Coronary Artery Bypass Surgery

BACKGROUND

The radial artery has been used for coronary artery bypass surgery for more than 25 years. The recent confirmation of the clinical benefits associated with the use of the artery is likely to drive a new interest toward this conduit in the next few years.

METHODS

A group of surgeons with extensive experience in the systematic use of the radial artery summarize here the key technical aspects of the use of the conduit for coronary bypass operations.

RESULTS

Preoperative evaluation of the ulnar collateral circulation and attention to the characteristics of the target vessel are keys for the successful use of the radial artery. Open or endoscopic harvesting can be used, preferentially with the aid of the harmonic scalpel. The use of vasodilatory and antispastic protocols is probably important but poorly supported by the current evidence. The radial artery can be used for multiple grafting strategies with a variable degree of technical complexity.

CONCLUSIONS

With attention to few technical key points, the radial artery is a versatile conduit that can be easily introduced in the everyday practice of coronary artery bypass surgery.

Long term outcomes of radial artery grafting in patients undergoing coronary artery bypass surgery

Single arterial left internal thoracic artery (LITA) based coronary artery bypass surgery (LITA-SABG) has been the principal revascularization strategy for over 25 years across all patient demographics. In line with the current emphasis being placed on personalized medicine, which tailors individual, patient-specific therapy to optimize outcomes, coronary artery bypass grafting (CABG) techniques have also evolved to achieve enhanced results among specific groups of patients with coronary artery disease. Most notable has been the development of multi-arterial bypass grafting (MABG) techniques, using either the radial artery (RA) or the right internal thoracic artery (RITA) in conjunction with the LITA, as both techniques have been shown to enhance long term survival of CABG patients. This article reviews the latest data on the long-term outcomes of RA-MABG and considers its impact in various sub-cohorts of CABG that are increasingly being treated by cardiac surgeons. The primary aim of this review is to highlight the advantages of RA-MABG over LITA-SABG and thereby potentiate its adoption into clinical practice. Our secondary aim is to summarize the results of RA-MABG in specific CABG sub-cohorts, to more closely align CABG surgery with the emerging consensus that personalized medicine enhances healthcare value.

Optimal management of radial artery grafts in CABG: Patient and target vessel selection and anti-spasm therapy

The current literature on radial artery grafting is reviewed focusing on the optimal deployment of radial artery grafts in coronary artery bypass surgery with specific attention to the selection of patients and target vessels for radial artery grafting.

Worldwide Trends in Multi-arterial Coronary Artery Bypass Grafting Surgery 2004-2014: A Tale of 2 Continents

Recent evidence shows that multi-arterial coronary artery bypass grafting (MABG) based on bilateral internal thoracic (BITA) or left internal thoracic (LITA) and radial artery (RA) improves long-term outcomes compared with single arterial coronary artery bypass grafting (SABG) (LITA + saphenous vein graft). How this evidence affected the worldwide use of MABG, if at all, is not well defined. Accordingly, we report 10-year temporal trends of MABG utilization from 2 continents. A study population of 1,683,434 non-emergent, primary, isolated LITA-based coronary artery bypass grafting (CABG) (≥2 grafts) patients was derived from the Society of Thoracic Surgeons (STS) (1,307,528 (79.5%) of 1,644,388 isolated CABG; total 1179 centers) and the Australia New Zealand Cardiothoracic (ANZ) Databases (34,213 (87%) of 39,046 isolated CABG; 24 centers) between 2004 and 2014. Patients were excluded based on the following: (1) no LITA, (2) if arterial grafts were other than RA or ITA, or (3) if grafting data were missing. The 3 MABG groups were LITA + RA, BITA, and BITA + RA, each with or without supplemental vein grafts. Grafting trends and their associated patient demographics were analyzed. SABG (89.3% STS, 51.4% ANZ) was the most common grafting strategy. MABG was most frequently accomplished by LITA + RA: (STS: 6.1%; ANZ: 42.6%), followed by BITA: (STS: 4.1%; ANZ: 4.3%), while ≥3 (BITA + RA) was rare in the STS (0.5%), but more common in ANZ (5.9%). In the STS, between 2004 and 2014, SABG rates systematically increased from 85.2% to 91.7%, BITA grafting was essentially unchanged from 3.6% to 4.3%, while RA use decreased systematically from 10.5% to 3.7%. In the ANZ, SABG rates increased from 17.3% to 51.4%, BITA grafting decreased from 6.3% to 3.6%, while RA grafting decreased from 65.8% to 39.0%. Compared with SABG patients, BITA patients were younger (STS: median age 59 vs 66, P < 0.001; ANZ: mean age 62 vs 68, P < 0.001), predominately male (STS: 84% vs 73%, P < 0.001; ANZ: 86% vs 79%, P < 0.001), less obese (body mass index >30 kg/m²) in STS (37% vs 42%, P < 0.001), more obese in ANZ (33% vs 32%, P = 0.001), and less diabetic (STS: 26% vs 43%, P < 0.001; ANZ: 25% vs 37%, P < 0.001), whereas RA patients were intermediate in age (STS: 61; ANZ: 65), in male sex (STS: 82%; ANZ: 81%), in the prevalence of diabetes (STS: 40%; ANZ: 34%), and were most obese (STS: 47%; ANZ: 34%). A decade-long analysis of STS data reveals a counterintuitive decline in the use (driven by decreasing RA use) of MABG: a potentially superior grafting strategy compared with SABG. In contra distinction, the smaller but growing ANZ data document a distinctly different CABG practice pattern, with a higher MABG utilization rate, but a similarly declining RA use. The reasons for these practice patterns and declining MABG are likely diverse and require further assessment.

The Surgical Treatment of Coronary Artery Occlusive Disease: Modern Treatment Strategies for an Age Old Problem

Coronary artery disease remains a formidable challenge to clinicians. Percutaneous interventions and surgical techniques for myocardial revascularization continue to improve. Concurrently, in light of emerging data, multiple practice guidelines have been published guiding clinicians in their therapeutic decisions. The multidisciplinary Heart Team concept needs to be embraced by all cardiovascular providers to optimize patient outcomes.

Radial Artery as a Coronary Artery Bypass Conduit: 20-Year Results

BACKGROUND

There is a lack of evidence for the choice of the second conduit in coronary surgery. The radial artery (RA) is a possible option, but few data on very-long-term outcomes exist.

OBJECTIVES

This study describes 20-year results of RA grafts used for coronary artery bypass grafting and the effects of RA removal on forearm circulation.

METHODS

We report the results of the prospective 20-year follow-up of the first 100 consecutive patients who received the RA as a coronary bypass conduit at our institution.

RESULTS

Follow-up was 100% complete. There were 64 deaths, 23 (35.9%) from cardiovascular causes. Kaplan-Meier 20-year survival was 31%. Of the 36 survivors, 33 (91.6%) underwent RA graft control at a mean of 19.0 ± 2.5 years after surgery. The RA was found to be patent in 24 cases (84.8% patency). In the overall population, probability of graft failure at 20 years was 19.0 ± 0.2% for the left internal thoracic artery (ITA), 25.0 ± 0.2% for the RA, and 55.0 ± 0.2% for the saphenous vein (p = 0.002 for RA vs. saphenous vein, 0.11 for RA vs. ITA, and p < 0.001 for ITA vs. saphenous vein). Target vessel stenosis >90%, but not location of distal anastomosis, significantly influenced long-term RA graft patency. No patients reported hand or forearm symptoms. The ulnar artery diameter was increased in the operated arm (2.44 ± 0.43 mm vs. 2.01 ± 0.47 mm; p < 0.05) and correlated with the peak systolic velocity of the second palmar digital artery (Pearson coefficient: 0.621; p < 0.05).

CONCLUSIONS

The 20-year patency rate of RA grafts is good, and not inferior to the ITA, especially when the conduit is used to graft a vessel with >90% stenosis. RA harvesting does not lead to hand or forearm symptoms, even at a very-long-term follow-up.

Long-term morphofunctional remodeling of internal thoracic artery grafts: a frequency-domain optical coherence tomography study

BACKGROUND

Internal thoracic arteries (ITAs) are frequently anastomosed to the coronary circulation for bypass grafting. The purpose of this research was to investigate in vivo the long-term morphofunctional changes of ITAs after their use as coronary artery bypass conduits, by comparing the morphological features and vasoreactivity of the grafted left ITA (LITA) with the native, nonharvested right ITA (RITA) in the same patient.

METHODS AND RESULTS

At least 10 years after surgery, in 10 patients, LITA graft and nonharvested RITA were assessed by quantitative angiography and frequency-domain optical tomography. Endothelium-dependent and independent vasodilation was tested by selective infusion of acetylcholine and isosorbide dinitrate. Quantitative angiography showed that baseline mean diameter of LITA graft was significantly smaller than that of RITA (2.59 mm [2.29-3.04] versus 3.05 mm [2.75-3.32]; P=0.01). LITA showed a significant intimal thickening (P=0.05) and a nonsignificant medial thinning (P=0.22) compared with RITA, leading to an increased intima-media ratio (intima-media ratio, 0.72 [0.53-0.91] versus 0.23 [0.12-0.38]; P=0.02). The intima-media ratio correlated inversely with the vasodilatatory response in RITA (r=-0.68, P=0.03 for acetylcholine and r=-0.62, P=0.05 for isosorbide dinitrate) but not in LITA (r=-0.18, P=0.63 for acetylcholine and r=-0.11, P=0.75 for isosorbide dinitrate).

CONCLUSIONS

Ten years after implantation to the coronary circulation, LITA grafts show intimal thickening, increased intima/media ratio, and maintained endothelium-derived vasodilation. These changes are likely to be an adaptive answer to the different flow dynamics typical of coronary circulation.

Characteristics of the actions by which 5-hydroxytryptamine affects electrical and mechanical activities in rabbit jugular vein graft

BACKGROUND AND PURPOSE

The vasomodulating actions of 5-HT in vein grafts, and the underlying mechanisms, remain to be fully clarified. Here, we characterized the actions by which 5-HT affects electrical and mechanical activities in rabbit autologous jugular vein grafts.

EXPERIMENTAL APPROACH

Smooth muscle cell (SMC) membrane potential and isometric tension were measured in vein grafts 4 weeks after implantation into carotid arteries. Changes in the expression of 5-HT receptor subtypes and in myosin heavy chain isoforms (SM1, SM2 and SMemb) were examined by immunohistochemistry and Western blot analysis.

KEY RESULTS

The walls of grafted veins displayed massive increases in the number of SM1- and SM2-positive SMCs. 5-HT induced a large depolarization and contraction that were each reduced by both 5-HT(2A) - and 5-HT(1B/1D) -receptor antagonists. The 5-HT-induced contraction was not modified by a 5-HT₇ -receptor antagonist. The 5-HT₇ -receptor-selective agonist AS 19 did not induce relaxation during the contraction to prostaglandin F(2α) . Immunohistochemical and Western blot analyses revealed that immunoreactive responses against 5-HT(2A) and 5-HT(1B/1D) receptors were increased in the vein graft.

CONCLUSIONS AND IMPLICATIONS

5-HT is able to induce a large contraction in rabbit autologous jugular vein grafts through (i) an increased number of differentiated contractile SMCs; (ii) an increased number of SMCs expressing contractile 5-HT(2A) - and 5-HT(1B/1D) receptors; and (iii) a down-regulation of the function of the relaxant SMC 5-HT₇ receptors. These changes in the vein graft may help it to resist the higher pressure present on the arterial side of the circulation.

Low-level-laser irradiation induces photorelaxation in coronary arteries and overcomes vasospasm of internal thoracic arteries

BACKGROUND AND OBJECTIVE

As low-level laser irradiation (LLLI) seems to induce vasodilation besides many other known biological effects, LLLI has been increasingly used in therapy of medical conditions with various irradiation parameters. The aim of this study was to investigate the effect of LLLI on photorelaxation of human coronary and internal thoracic arteries (ITA).

MATERIALS AND METHODS

Thirty vessel segments of ITA used for routine coronary artery bypass grafting as well as left anterior descending coronary arteries (LAD) of patients undergoing cardiac transplantation were cut into 4-mm rings stored in a modified Krebs-Henseleit solution and evaluated in a myograph. Both types of vessel segments were irradiated by a semiconductor non-thermal GaAs diode laser operating at a wavelength of 680 nm. After precontraction with thromboxane agonist U44619, respective relaxation responses were evaluated and compared to pharmacological dilatation induced by substance P.

RESULTS

Mean pharmacological vasodilation by substance P was 22.6 ± 3.3%, 12.8 ± 1.4%, and 20.4 ± 3.2% in macroscopic healthy LAD, LAD with atheromatous plaque, and ITA, respectively. Average photorelaxation induced by LLLI was 16.5 ± 2.0%, 1.9 ± 1.7%, and 6.8 ± 4.7%, accordingly. Vasodilatatory responses induced either by substance P or administration of LLLI were significantly decreased in LAD with atheromatous plaque (P < 0.0001). Vasospasms of ITA segments occurring during experiments could be abandoned when LLLI was administered.

CONCLUSION

Macroscopic healthy LAD exposed to LLLI revealed significant photorelaxation. With the administration of LLLI, 73% of the maximal obtainable effect by an endothelium-dependent vasodilator could be reached. Furthermore, LLLI has the potential to overcome vasospasms of ITA.

Decellularized, xenogeneic small-diameter arteries: transition from a muscular to an elastic phenotype in vivo

Reports regarding the biocompatibility of xenogeneic, decellularized bioprosthetic implants differ between bioinertness and complete graft degradation. We investigated heparin-crosslinked and nonheparinized, xenogeneic vascular substitutes in a rat model. Porcine arteries (15 x 1.5 mm) were decellularized by multistep detergent and enzymatic techniques, which were followed by heparin-crosslinking in 50% of the implants. Prostheses were implanted into the abdominal aorta of 76 rats for 1 day and up to 6 months. Retrieved specimens were evaluated by histology, immunohistochemistry, laser scanning, and scanning electron microscopy. Graft patency did not differ between groups (97.3%). Heparinized grafts showed a statistically significant lower rate of aneurysm formation (p = 0.04 %). Implants revealed infiltration with granulocytes and macrophages up to 3 months. Recellularization with endothelial cells and myofibroblasts was detectable within 1 month. After 6 months elastin biosynthesis and complete graft remodeling toward an elastic vessel was evident. These results indicate that temporary inflammation does not interfere with long-term vascular remodeling.