Graft Preservation Solution DuraGraft® Alleviates Vascular Dysfunction Following In Vitro Ischemia/Reperfusion Injury in Rats

Vascular ischemia/reperfusion injury (IRI) in patients undergoing coronary artery bypass grafting can result in graft failure and the need for repeat revascularization procedures. DuraGraft® has been shown to protect structure and function in saphenous vein grafts against IRI. We compared the effect of DuraGraft® to saline solution on arterial grafts submitted to IRI. Rat thoracic aortic rings were harvested and immediately mounted in organ bath chambers (control, n = 7 rats) or underwent cold ischemic preservation either in saline (IR, n = 9 rats) or DuraGraft® (IR+Dura, n = 9 rats). Vascular function was measured ex vivo and immunohistochemistry was performed. Impaired maximum vasorelaxation (Rmax) to ACh in the IR-group compared to controls was ameliorated by DuraGraft®, indicating an improvement in endothelial function (Rmax to ACh (%): IR + Dura 73 ± 2 vs. IR 48 ± 3, p < 0.05). Additionally, decreased aortic ring sensitivity to ACh (pD2-value: -log 50% maximum response) seen after IR in the saline group was increased by DuraGraft® (pD2 to ACh: IR+Dura 7.1 ± 0.1 vs. IR 6.3 ± 0.2, p < 0.05). Impaired maximum contractile response to phenylephrine and high potassium chloride concentrations in the IR group compared to controls was significantly improved by DuraGraft®. DuraGraft® alleviates vascular dysfunction following IRI by reducing nitro-oxidative stress and the expression of ICAM-1, without leukocytes engagement.

Never again. Once used for cardiac catherization the Radial Artery cannot be used for CABG.

The use of the Radial Artery (RA) as a conduit in coronary artery bypass grafting (CABG) has been steadily increasing since the early 1990’s and based on the most recent data may well become the standard of care for patients with multi-vessel coronary artery disease (CAD) requiring multiple arterial grafts. The TRA approach for cardiac catherization has also increased steadily in use by interventional cardiologists owing to its reduction in bleeding and vascular complications when compared with the femoral approach and is now considered the preferred arterial access. However, prior use of transradial access (TRA) for cardiac catherization is a contra-indication for the use of the RA for CABG because of high rates of structural damage to the vascular wall and potential for graft failure. In this issue of the Journal of Cardiac Surgery Clarke et al. examine the RA of two patients who had TRA for coronary angiography 8 and 12 years prior and note that both patients had chronic injury with dissection and obstruction of the lumen secondary to fibrosis suggesting that TRA causes long-term and irreversible damage rendering them unsuitable as conduits for CABG.

Does Age Affect the Short- and Long-Term Outcomes of Coronary Bypass Grafting?

The etiology of coronary artery disease (CAD) is multifactorial, stemming from both modifiable and nonmodifiable risk factors such as age. Several studies have reported the effects of age on various outcomes of coronary artery bypass grafting (CABG). This article reviews age-related outcomes of CABG and offers direction for further studies in the field to create comprehensive, evidence-based guidelines for the treatment of CAD. Ninety-two primary sources were analyzed for relevance to the subject matter, of which 17 were selected for further analysis: 14 retrospective cohort studies, 2 randomized clinical trials, and 1 meta-analysis. Our review revealed four broad age ranges into which patients can be grouped: those with CAD (1) below the age of 40 years, (2) between the ages of 40 and 60 years, (3) between the ages of 60 and 80 years, and (4) at or above 80 years. Patients below the age of 40 years fare best overall with total arterial revascularization (TAR). Patients between the ages of 40 and 60 years also fare well with the use of multiarterial grafts (MAGs) whereas either MAGs or single-arterial grafts may be of significant benefit to patients at or above the age of 60 years, with younger and diabetic patients benefitting the most. Arterial grafting is superior to vein grafting until the age of 80 years, at which point there is promising evidence supporting the continued use of the saphenous vein as the favored graft substrate. Age is a factor affecting the outcomes of CABG but should not serve as a barrier to offering patients CABG at any age from either a cost or a health perspective. Operative intervention starts to show significant mortality consequences at the age of 80 years, but the increased risk is countered by maintenance or improvement to patients' quality of life.

Whatever happens, two mammary is better than one

It is well known that the left internal mammary artery (LIMA) should be the first conduit of choice. Similarly, especially in patients younger than 70 years, other conduits should be search among arterial grafts such as right internal mammary artery (RIMA) or radial artery (RA). If the RA can be harvested in the meanwhile of LIMA harvesting without time consuming, it is well established that former one has to be grafted only on presence of a good run-off. One of the main criticisms moved to the use of RIMA are linked to technical difficulties in its harvesting it. Edgar Aranda-Michel and coworkers tried to answer to the age-old question is “RIMA has to be used in situ or free-graft?” In a retrospective study on 667 patients (442 had free RIMA and 245 had free RIMA) that were also matched through propensity analysis (202 patients per group), they did not find any differences between the two groups in the major outcomes, including heart failure specific readmissions. This finding is consistent with the literature, hence the take-home message is whatever happens, two mammary is better than one.

Radial artery as a second conduit gains momentum: The RAPCO trial

In coronary artery bypass grafting (CABG), the use of an internal mammary artery (IMA) to graft the left anterior descending coronary artery (LAD) improves survival and reduces the need for repeat revascularization. The other IMA, radial artery (RA), and saphenous vein (SV) have contested to complete the surgical revascularization. For that purpose, SV remains the most commonly used conduit despite current evidence in favor of arterial grafts. To determine which conduit is best for grafting the second most important coronary artery, Buxton and colleagues have recently published the long term results of their “Radial Artery Patency and Clinical Outcomes (RAPCO)” trial.

Heparin-Eluting Tissue-Engineered Bioabsorbable Vascular Grafts

The creation of small-diameter tissue-engineered vascular grafts using biodegradable materials has the potential to change the quality of cardiovascular surgery in the future. The implantation of these tissue-engineered arterial grafts has yet to reach clinical application. One of the reasons for this is thrombus occlusion of the graft in the acute phase. In this paper, we first describe the causes of accelerated thrombus formation and discuss the drugs that are thought to inhibit thrombus formation. We then review the latest research on methods to locally bind the anticoagulant heparin to biodegradable materials and methods to extend the duration of sustained heparin release. We also discuss the results of studies using large animal models and the challenges that need to be overcome for future clinical applications.