Patency of conduits in patients who received internal mammary artery, radial artery and saphenous vein grafts

Comparison of the mechanical properties of bypass grafts: Experimental assays

OBJECTIVE

One prevalent therapeutic strategy for addressing atherosclerosis is using an alternative blood supply route to the heart, referred to as bypass surgery. In these surgeries, the saphenous vein, radial artery, and internal mammary artery are commonly used to create this bypass route. Unfortunately, due to negligence regarding the compatibility of the graft with the host tissue, reoperation is often required after several years. One method that can aid in selecting a suitable vein for bypass is simulating the solid-fluid interaction, and performing such simulations requires knowledge of the mechanical properties of bypass grafts. Therefore, extracting the mechanical properties of bypass grafts is essential.

METHODS

In this study, human bypass grafts were subjected to uniaxial tensile testing, and their elastic modulus was extracted and compared. Additionally, the hyperelastic properties of these grafts were extracted using the Mooney-Rivlin model for use in numerical software.

RESULTS

The average elastic modulus in the circumferential direction for radial artery, mammary artery, and saphenous vein samples were determined to be 1.384 ± 0.268 MPa, 3.108 ± 1.652 MPa, and 7.912 ± 2.509 MPa, respectively. Based on the results of uniaxial tests, the saphenous vein exhibited the highest stiffness among the three vascular tissues.

CONCLUSION

The mechanical characterization results of the bypass vessels can be applied to the clinical studies of heart diseases. They may help develop an appropriate treatment approach.

Application of the radial artery after angiography in patients undergoing total arterial coronary revascularization

OBJECTIVE

There is growing evidence supporting the utilization of the radial artery as a secondary arterial graft in coronary artery bypass grafting (CABG) surgery. However, debates continue over the recovery period of the radial artery following angiography. This study aims to evaluate the clinical outcomes and experiences related to the use of the radial artery post-angiography in total arterial coronary revascularization.

METHODS

A retrospective analysis was performed on data from patients who underwent total arterial CABG surgery at the University of Hong Kong Shenzhen Hospital from July 1, 2020, to September 30, 2022. Preoperative assessments included ultrasound evaluations of radial artery blood flow, diameter, intimal integrity, and the Allen test. Additionally, pathological examinations of the distal radial artery and coronary artery CT angiography were conducted, along with postoperative follow-up to assess the safety and efficacy of using the radial artery in patients undergoing total arterial CABG.

RESULTS

A total of 117 patients, compromising 102 males and 15 females with an average age of 60.0 ± 10.0 years, underwent total arterial CABG. The internal mammary artery was used in situ in 108 cases, while in 4 cases, it was grafted to the ascending aorta due to length limitations. Bilateral radial arteries were utilized in 88 patients, and bilateral internal mammary arteries in 4 patients. Anastomoses of the proximal radial arteries to the proximal ascending aorta included 42 cases using distal T-anastomosis and 4 using sequential grafts. The interval between bypass surgery and coronary angiography ranged from 7 to 14 days. Pathological examination revealed intact intima and continuous elastic membranes with no significant inflammatory infiltration or hyperplastic lumen stenosis in the radial arteries. There were no hospital deaths, 3 cases of perioperative cerebral infarction, 1 secondary thoracotomy for hemorrhage control, 21 instances of intra-aortic balloon pump (IABP) assistance, and 2 cases of poor wound healing that improved following debridement. CT angiography performed 2 weeks post-surgery showed no internal mammary artery occlusions, but 4 radial artery occlusions were noted.

CONCLUSION

Ultrasound may be used within 2 weeks post-angiography to assess the recovery of the radial artery in some patients. Radial arteries with intact intima may be considered in conjunction with the internal mammary artery for total arterial coronary CABG. However, long-term outcomes of these grafts require further validation through larger prospective studies.

From a Position of Known Angiographic Perfect Patency: What Happens Next?

BACKGROUND AND AIM

The biological behaviour of coronary graft conduits over time may be considered by serial angiography.

METHODS

A single institution retrospective cohort received mostly clinically indicated angiography between 1997 and 2020, following coronary bypass surgery. Only perfectly patent grafts (absence of any lumen irregularity) for each conduit type at the first postoperative angiogram were selected for a later comparison. The latest angiograms were at least 5 years postoperatively, and at least 1 year after first postoperative angiogram. Analysis was done according to each graft (anastomosis). Comparisons used generalised estimating equations, adjusted for binary logistic regression.

RESULTS

Of 143 patients, there were 410 of 468 (87.6%) perfectly patent grafts at the first angiogram, analysed at 6.8±4.0 years postoperative, of which 157 were internal mammary arteries, 228 were radial arteries, and 25 were saphenous veins. At the latest angiogram (12.2±3.8 years postoperative), comparison with the first angiogram for each individual graft found preserved perfect patency for internal mammary arteries, 156 of 157 (99.4%), and for radial arteries, 227 of 228 (99.6%) but saphenous veins deteriorated considerably, 13 of 25 (52.0%). The two arterial grafts (internal mammary and radial) were superior to vein grafts (odds ratio 163; 95% confidence interval [CI] 22-1,211; p<0.001), but not different from each other (odds ratio 0.95; 95% CI 0.78-1.16; p=0.584).

CONCLUSIONS

From a position of known angiographic perfect patency post-CABG, internal mammary artery and radial artery grafts retained their perfect patency in the longer term, but saphenous vein grafts did not.

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.

Early and Mid-Term Outcomes of Coronary Artery Bypass Grafting in Adults With Congenital Heart Disease

Atherosclerotic coronary artery disease (CAD) is well-studied in acquired cardiac diseases; however, little data exist regarding outcomes of adult congenital heart disease (ACHD) with CAD. This study examined patients who underwent coronary artery bypass grafting (CABG) during repair of ACHD. This was a retrospective study of patients who underwent CABG for CAD concomitant with ACHD repair 1972-2021. Demographic information, ACHD diagnosis, surgical history, operative details, and outcomes were analyzed. Data are presented as median (interquartile range [IQR]). 157 patients were identified with a median age of 63 (IQR 17) years. Left anterior descending (LAD) was the predominant diseased artery (109 patients [69%]); of those 83 (76%) were treated with mammary artery. 90 (57.3%) patients had 1 bypass, 42 (26.7%) 2, 19 (12%) 3, and 6 (3.8%) had 4. There has been no early mortality since 1988. There was no long-term survival difference between the patients with LAD disease treated with mammary compared to vein (P = 0.68), but early mortality was higher in those treated with vein (10.3% vs 0%, P = 0.018). Late recurrent angina was found in 18 patients (12%) and recurrent CAD found in 17 patients (11%), with 16 patients (10%) requiring CAD reintervention. At most recent follow-up (7.2 [IQR 11.4] years), 101 (64.3%) patients were deceased at 10 (IQR 13.1) years after surgery. Surgical revascularization for CAD may be necessary during the treatment of ACHD, most commonly for LAD disease. Early mortality was low in recent decades. Continued surveillance for recurrent CAD is required.

Small Diameter Cell-Free Tissue-Engineered Vascular Grafts: Biomaterials and Manufacture Techniques to Reach Suitable Mechanical Properties

Vascular grafts (VGs) are medical devices intended to replace the function of a blood vessel. Available VGs in the market present low patency rates for small diameter applications setting the VG failure. This event arises from the inadequate response of the cells interacting with the biomaterial in the context of operative conditions generating chronic inflammation and a lack of regenerative signals where stenosis or aneurysms can occur. Tissue Engineered Vascular grafts (TEVGs) aim to induce the regeneration of the native vessel to overcome these limitations. Besides the biochemical stimuli, the biomaterial and the particular micro and macrostructure of the graft will determine the specific behavior under pulsatile pressure. The TEVG must support blood flow withstanding the exerted pressure, allowing the proper compliance required for the biomechanical stimulation needed for regeneration. Although the international standards outline the specific requirements to evaluate vascular grafts, the challenge remains in choosing the proper biomaterial and manufacturing TEVGs with good quality features to perform satisfactorily. In this review, we aim to recognize the best strategies to reach suitable mechanical properties in cell-free TEVGs according to the reported success of different approaches in clinical trials and pre-clinical trials.

Aortic Coarctation Effect on Atherosclerosis of the Left Internal Mammary Artery: A Case Presentation and Literature Review

Atherosclerosis of the internal mammary artery (IMA) is an uncommon disease. We present a case report of a patient with stable angina who had a history of coarctation repair. After meticulous investigation and discussion, a coronary artery bypass graft (CABG) was planned. During the surgery, we found that the left internal mammary artery (LIMA) was severely atherosclerotic without any blood flow, and a fragment of LIMA was taken for histopathological examination for further insight into pathogenesis. Vein grafts were alternatively used. Furthermore, relevant literature review and management were discussed for the use of LIMA in patients with a history of aortic coarctation.

Diagnostic and Prognostic Value of miRNAs after Coronary Artery Bypass Grafting: A Review

MiRNAs are noncoding, 21-24 nucleotide-long RNA particles that control over 60% of genes. MiRNAs affect gene expression through binding to the 3'-untranslated region of messenger RNA (mRNA), thus inhibiting mRNA translation or inducing mRNA degradation. MiRNAs have been associated with various cardiovascular diseases, including heart failure, hypertension, left ventricular hypertrophy, or ischemic heart disease. In addition, miRNA expression alters during coronary artery bypass grafting (CABG) surgery, which could be used to predict perioperative outcomes. CABG is an operation in which complex coronary arteries stenosis is treated by bypassing atherosclerotic lesions with venous or arterial grafts. Despite a very low perioperative mortality rate and excellent long-term survival, CABG is associated with postoperative complications, including reperfusion injury, graft failure, atrial fibrillation and perioperative myocardial infarction. So far, no reliable diagnostic and prognostic tools to predict prognosis after CABG have been developed. Changes in the perioperative miRNA expression levels could improve the diagnosis of post-CABG myocardial infarction and atrial fibrillation and could be used to stratify risk after CABG. Herein, we describe the expression changes of different subtypes of miRNAs during CABG and review the diagnostic and prognostic utility of miRNAs in patients undergoing CABG.

Comparative study of coronary artery bypass graft materials: reduced contraction and ADMA levels in internal mammary artery versus saphenous vein

BACKGROUND

Vasospasm and atherosclerosis due to low endothelial capacity are the most important causes of coronary artery bypass graft failure observed in internal mammary artery (IMA) and saphenous vein (SV). Vasospasm can be mimicked in in vitro studies by inducing vasoconstriction of graft materials. In the present study, we aimed to compare the vascular contraction induced by several spasmogens including prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2α), phenylephrine (PE), leukotriene C4 (LTC4), LTD4, potassium chloride (KCl), and arachidonic acid between IMA and SV preparations. Furthermore, endothelial capacity, nitrite and asymmetric dimethylarginine (ADMA) levels were compared between two grafts.

METHODS

By using organ bath, contractile responses induced by different spasmogens were compared between IMA and SV preparations derived from patients underwent coronary artery bypass surgery (n=35). The endothelial capacity was determined by acetylcholine (ACh) -induced relaxation in PE-precontracted vessels. Nitrite and ADMA levels were measured in organ culture supernatant of IMA and SV preparations.

RESULTS

Contractile responses induced by PGE2, PGF2α, PE, LTC4, LTD4, KCl and arachidonic acid were significantly lower in IMA preparations versus SV preparations. ACh-induced relaxation was significantly more prominent in IMA than SV preparations. Nitrite levels were greater and ADMA levels were lower in IMA versus SV preparations.

CONCLUSIONS

IMA has reduced capacity to constrict to several vasoconstrictor agents. Furthermore, IMA has greater endothelial capacity associated with higher nitrite levels and lower ADMA levels. Our results support the greater patency rate observed in IMA versus SV preparations.

The relationship between dual antiplatelet treatment (DAPT) score and saphenous venous grafts patency after coronary artery bypass grafting surgery

BACKGROUND

Coronary artery bypass grafting (CABG) remains the gold standard treatment for mutivessel and left main coronary artery disease (CAD). Saphenous vein graft (SVG) patency is still a problem in CAD patients after CABG surgery. The Dual Antiplatelet Treatment (DAPT) score is a clinical prediction tool that predicts ischaemic and bleeding risk in CAD patients. The aim of this study is to investigate the relationship between DAPT score and SVG patency in CABG patients.

METHOD

This retrospective study enrolled a total of 398 patients (68 female; mean age 65.8 ± 9.1 years) with a history of CABG surgery. The study population was divided into two subgroups according to SVG patency. The DAPT score was calculated for each patients and compared between the two groups.

RESULTS

Coronary angiography revealed SVG disease in 212 patients and SVG patency in 186 patients. The rates of diabetes mellitus and hypertension, red cell distribution width values, DAPT Score, time interval after CABG and number of SVGs were significantly higher while LVEF was significantly lower in patients with SVG disease. The presence of diabetes mellitus, high DAPT score, long time interval after CABG and high number of SVGs were found to be independent predictors of SVG patency. DAPT score above 2.5 predicted SVG disease with a sensitivity of 77.1% and a specificity of 87.1% (AUC: 0.873; 95%CI: 0.823-0.924; p < 0.001).

CONCLUSION

The DAPT score may provide useful information for SVG patency in CABG patients. Patients with high DAPT score should be followed up closely for SGV occlusion. DAPT score may be useful prior to CABG in determining the duration of dual anti-platelet therapy and in encouraging the use of arterial grafts with better patency.

Early cardiac contractility outcome of reoperative coronary artery bypass grafting using right gastroepiploic artery

BACKGROUND AND AIM OF THE STUDY

Reoperative coronary artery bypass grafting (redo CABG) still carries higher mortality and increased morbidity compared with primary CABG. In this study, we retrospectively reviewed our operative outcome of redo CABG to evaluate the impact of the left anterolateral thoracotomy approach using the right gastroepiploic artery (RGEA).

METHODS

Between 1994 and 2020, 11 patients (mean age 60.3 ± 13.1 years; nine men, two women) underwent isolated redo CABG using the RGEA via the left anterolateral thoracotomy.

RESULTS

The mean duration from the initial CABG was 128.3 ± 88.4 months. Redo CABG was performed because of graft occlusion in six patients (54.5%), graft stenosis in one patient (9.1%), and progressive disease of previously ungrafted vessels in four patients (36.4%). The total number of bypasses using RGEA (including Y-composite vein grafts) was 16 (four left anterior descending branches, two diagonal branches, five circumflex branches, five right coronary arteries). No residual graft injury, major comorbidity, or in-hospital death was observed. Changes in echocardiographic values before and after redo CABG were 210.9 ± 48.2 ml and 175.0 ± 41.4 ml in left ventricular end-diastolic volume, 130.2 ± 49.2 ml and 94.4 ± 33.0 ml in left ventricular end-systolic volume, and 45.6 ± 11.0% and 52.2 ± 10.7% in left ventricular ejection fraction, respectively. These parameters significantly improved after redo CABG.

CONCLUSIONS

Redo CABG with RGEA grafting via the left anterolateral thoracotomy approach is a safe and effective surgical procedure especially in improving cardiac contractility in patients who required revascularization.

The use of free versus in situ right internal mammary artery in coronary artery bypass grafting

INTRODUCTION

Coronary artery bypass grafting (CABG) continues to be the most commonly performed cardiac surgical procedure in the world. The use of multiarterial grafting may confer a long-term survival benefit over the use of vein grafts. However, there is a paucity of data comparing the use of in situ versus free right internal mammary artery (RIMA) in isolated CABG.

METHODS

Patients that underwent isolated CABG between 2010 and 2018 where RIMA was used in addition to a left internal mammary artery graft. Patients with prior cardiac surgery or percutaneous coronary intervention were excluded. Propensity matching was used for subanalysis. Mortality and major adverse cardiac and cerebrovascular events (MACCE) were analyzed with Kaplan-Meier survival curves and Cox multivariable regression. Heart failure-specific readmissions were assessed with cumulative incidence curves with Fine and Gray competing risk regression.

RESULTS

A total of 667 patients underwent isolated CABG. Of those, 422 had free RIMA and 245 had in situ RIMA utilized. Mortality was similar between cohorts (p = 0.199) with 5-year mortality rates of 6.6% (free) and 4.1% (in situ). MACCE was similar between cohorts, with 5-year event rates of 33.6% and 33.9% (p = 0.99). RIMA style was not a significant predictor of any outcome.

CONCLUSION

There was no difference in long-term mortality, complications, MACCE, or heart failure readmissions when comparing a contemporary cohort of patients undergoing isolated CABG utilizing RIMA as a conduit. These data may allow surgeons to consider using RIMA either as an in situ or a free conduit.

Plateletcrit may predict no-reflow after saphenous vein graft interventions in patients with non-ST elevation myocardial infarction

Saphenous vein graft (SVG) percutaneous coronary interventions (PCIs) are procedures with potential complications such as distal embolization, slow or no-reflow phenomenon. Platelets are the main factors in development of thrombus and no-reflow phenomenon. There have been multiple studies that identified the association between plateletcrit (PCT) and cardiovascular outcomes. The aim of the study was to investigate whether PCT can predict the development of no-reflow in patients with non-ST elevation myocardial infarction (NSTEMI) undergoing PCI for SVG disease. A total of 181 patients who underwent PCI for SVG disease with NSTEMI were included retrospectively. Platelet indices on admission were recorded. Patients were divided into two groups according to the development of no-reflow during the procedure: no-reflow (n = 32; 18%) and normal reflow (n = 149; 82%). PCT and platelet count were higher in the no-reflow group (0.254 vs. 0.224, P = 0.020; 265.4 vs. 233, P = 0.011, respectively). The PCT cut-off value for predicting no-reflow was calculated as 0.230 by ROC curve analysis with 68.8% sensitivity and 51.0% specificity. Multivariate logistic regression analysis showed that PCT was an independent predictor of no-reflow (odds ratio: 5.091, confidence interval: 1.356-19.116, P = 0.016). PCT may be useful in identifying patients at risk for developing no-reflow in patient with NSTEMI undergoing SVG PCI.