Radial Artery Conduits Research Articles

Safety of the Extended Radial Artery Conduit in Performing Complete Arterial Revascularization

We have developed a technique to elongate the radial artery (RA) with the distal segment of the left internal thoracic artery. This study investigated the safety and durability of this extended conduit compared with the composite Y-grafts. From January 1998 through December 2010, 750 patients underwent complete arterial revascularization with the use of the left internal thoracic artery (LITA) and RA. Out of these patients, 362 patients were operated on with the use of either RA-LITA extension conduit (n = 103), or a composite LITA-RA Y-graft (n = 259) and were included in this study. Cox regression analyses and Kaplan-Meyer survival curves were used to identify the predictive value of the RA-LITA extension technique on both survival and incidence of re-intervention. Cox regression analysis showed that the use of RA-LITA extension conduit was not a significant predictor of re-intervention (p = 0.600) or total survival (p = 0.930).Kaplan-meier curves showed no significant difference between the two groups concerning total survival and re-intervention-free survival (p = 0.600). Our alternative technique of extending the RA with the distal segment of the LITA is a safe alternative for patients undergoing total arterial revascularization. The long-term survival and incidence of re-intervention is comparable with the composite LITA-RA Y-grafts.

Comparative study on the histomorphology and molecular biology of radial artery conduits in patients with diabetes mellitus who underwent coronary bypass surgery

We studied the impact of diabetes mellitus (DM) on the radial artery (RA) in 30 patients with DM and 30 non-diabetic patients undergoing coronary artery bypass grafting with autologous RA. RAs were recorded as normal if there was no cellular or stromal tissue between the endothelium and the internal elastic lamina. The RA was normal in 26.7% of diabetic and 76.7% of non-diabetic patients (p = 0.000298). Intimal thickness index and intima:media ratio were higher in the former than in the latter (p < 0.05; p < 0.05), with no significant difference in luminal narrowing (p > 0.05). Electron microscopy scores were lower in the non-diabetic group (p < 0.001); endothelial nitric oxide synthase (eNOS) protein expression and optical density were higher (p < 0.001). Von Willebrand factor and endothelin-1 messenger RNA (mRNA) levels were higher in the DM patients (p < 0.001). The quality of the RA in patients with DM was thus inferior to that in non-diabetic patients. Care should be taken when selecting RA as a conduit in patients with DM.

Intraoperative Administration of Clevidipine to Prevent Vasospasm After Radial and Internal Mammary Artery Grafts During Coronary Artery Bypass Grafting

During coronary artery bypass graft surgery, various arterial and venous conduits have been used to carry blood flow from the aorta to the coronary vasculature. Arterial conduits provide certain advantages over the saphenous vein, including superior long-term patency, relative resistance to the development of atherosclerosis, and greater endothelium-dependent relaxation. However, the perioperative release of catecholamines and thromboxane A, mechanical manipulation, and underlying endothelial cell dysfunction may result in vasoconstriction or vasospasm of the arterial conduit and a compromise of myocardial perfusion. Given these issues, pharmacologic therapy is frequently initiated intraoperatively to prevent vasospasm. Clevidipine is a rapidly acting calcium channel antagonist. Like nicardipine, it is a member of the dihydropyridine subgroup. Its rapid metabolism by tissue and plasma esterases results in an effective half-life of 1 to 3 minutes. We report, for the first time, the perioperative use of clevidipine to prevent vasospasm after coronary artery bypass graft surgery with the use of internal mammary artery and bilateral radial artery conduits. Its potential application in this scenario and advantages when compared with other commonly used agents is discussed.

Comparison of the Radial Artery and Saphenous Vein as Composite Grafts in Off-Pump Coronary Artery Bypass Grafting in Elderly Patients: A Randomized Controlled Trial

Background and ObjectivesArterial grafts have a better long-term patency rate than saphenous vein (SV) when used in off-pump coronary artery bypass surgery (OPCAB). However, arterial grafts in elderly patients are often diseased. We sought to compare the early outcomes achieved by using the two different types of composite grafts.Subjects and MethodsWe conducted a randomized trial to compare radial artery (RA) and SV composite grafts based on the in situ left internal mammary artery in 60 elderly (>70 years old) patients, who were scheduled to undergo OPCAB. Clinical outcomes and 1-year postoperative CT angiography results were compared. The quality of the conduit was evaluated by employing vascular ultrasonography, optical coherence tomography (OCT), and histologic examination.ResultsNo differences in immediate postoperative morbidity and mortality were observed between the two groups. Early postoperative CT angiography revealed a SV patency rate of 100%, which was not different from that of RA composite grafts (99.1%). CT angiography after a year showed an overall patency rate of 96.3%. The overall patency rate of the SV group at 1 year was 94.7%, which was similar to that of the RA group (97.4%). Also, there was no difference in overall survival rate between the two groups. Vascular ultrasonographic images showed strong correlations between OCT and histopathology.ConclusionOur analysis of early outcomes revealed that the SV could be used as an alternative composite graft to the RA in elderly patients. Vascular ultrasonography is an accurate, real-time, and reproducible method for assessing the quality of the RA conduit.

Reappraisal of a 20-year experience with the radial artery as a conduit for coronary bypass grafting

This study aimed at evaluating the clinical and angiographic results of the radial artery (RA) used as a coronary bypass graft over 20 years. Clinical follow-up was obtained in 563 patients at 9.2 years. Angiographic follow-up was obtained in 351 patients with opacification of 1427 conduits, including 629 RA at 7.0 years. At 9.2 years, freedom from overall and cardiovascular death was 80.3% and 92.7%, respectively. Symptoms were: acute myocardial infarction: 2.1% (n=12); angina: 17.4% (n=98), and congestive heart failure 10.6% (n=60). Percutaneous revascularization was required in 13.5% (n=76) of cases on: native coronary (n=77), RA conduit (n=21), and other graft (n=7). Reoperation was needed in 2.3% (n=13) of cases for valve replacement (n=10) and redo coronary artery bypass grafting (CABG) (n=3). At 7.0 years, RA patency was 82.8% (521/629) and was lower than that of left internal mammary artery (IMA), 95.5% (491/514) (p<0.001); similar to right IMA, 87.9% (51/58, p=0.32); free IMA, 80.0% (44/55, p=0.60); and vein, 81.9% (140/171, p=0.77). RA patency was lower in the case of myocardial ischemia: 74.0% (174/235) versus 88.1% (347/394) in asymptomatics (p<0.001). RA patency was higher for diagonal (93.1% (95/102)) compared to circumflex (82.5% (274/332, p<0.01)) and right coronary (77.6% (146/188, p<0.001)). Calcium channel blockers had no impact on RA patency. Separating four groups at successive follow-up intervals, RA patency was: 86.2%, 81.9%, 81.4%, and 81.6% at 1.0, 5.4, 8.3, and 13.1 years, respectively. CABG with the RA offered long-lasting clinical benefit. Beyond the first postoperative year during which some attrition was observed, RA patency was remarkably stable for up to 20 years.

Effect of External Compression Bandage on Forearm Swelling, Discomfort, and Pain Following the Removal of a Radial Artery Conduit for CABGS

PURPOSE: Studies highlight the effectiveness of the radial artery (RA) as a conduit for CABGS however scant evidence describing management of the harvest site in the postoperative context exists. The purpose of this study was to determine whether a compression dressing effectively reduces forearm swelling, discomfort and pain in order to identify the optimal dressing choice for RA harvest site.

Vascular antispastic medication should take priority over other antihypertensives after coronary artery bypass grafting using a radial artery conduit

Radial artery conduits have recently been used more often in coronary artery bypass grafting because of their potentially better long-term patency than saphenous vein conduits. However, vasospasm of the radial artery conduit due to its nature as a muscular artery has always been of concern and a variety of vasodilators have empirically been used to reduce the risk of spasm. When a patient who was preoperatively taking antihypertensive agents undergoes coronary artery bypass using a radial artery graft, and if he/she is not hypertensive postoperatively, it is not always easy to decide what medication to start with. We report a case of a patient with a radial artery graft who did not receive vasodilators after surgery due to hypotension. The patient developed vasospasm of the radial artery conduit which did not respond to direct injection of vasodilators into the conduit but recovered after taking oral vasodilators for four weeks.

Endoscopic versus open radial artery harvesting for coronary artery bypass grafting

Background and aim of the study. The radial artery has become the artery of choice after both internal thoracic arteries for coronary artery bypass grafting (CABG). This study compares wound healing and arm complications after endoscopic versus open radial artery harvesting. Methods. From January 2002 to July 2004, 509 patients underwent CABG including a radial artery conduit. Thirty-nine had endoscopic and 470 conventional open radial artery harvesting. A propensity score was used to obtain 1:3 matching of all endoscopic to 117 open-harvesting patients. Postoperative wound healing, local neurologic deficits, wound infection, and pain scores were compared. Results. Wound healing: 34 of 39 endoscopic wounds exhibited a perfect Hollander score versus 339 of 470 open-harvest wounds (p = 0.01). Wound appearance was better for endoscopic harvesting (p = 0.004). Three incomplete neurologic deficits were observed after open harvesting versus one complete neurologic deficit after endoscopic harvesting that recovered prior to hospital discharge. Incidence of wound infection was similar in both groups (p = 0.7), although infection was more severe with open harvesting. Pain score was lower (p = 0.006) with endoscopic harvesting. Conclusions. Endoscopic radial artery harvesting was associated with better wound appearance and less pain. Occurrence of neurologic deficits and wound infection was infrequent in both groups.

Rare Bleeding Complication of the Radial Artery Conduit after Coronary Artery Bypass Grafting with Endoscopic Harvesting

A 79-year-old man with unstable angina developed localized left atrial tamponade after conventional coronary artery bypass grafting (CABG) with endoscopic radial artery harvesting (ERAH). Hemodynamic instability developed several hours after the systemic heparinization. Transthoracic and later intraoperative transesophageal echocardiography revealed a large, isolated hematoma compressing the left atrium. The radial artery for the circumflex artery bled during an emergent re-sternotomy. Incomplete hemostasis of the radial artery by ERAH was the likely cause of this serious complication. Surgeons, especially those who are new to ERAH, should examine the harvested radial arterial conduit carefully and confirm complete hemostasis before performing the procedure.

Persistent sensitivity disorders at the radial artery and saphenous vein graft harvest sites: a neglected side effect of coronary artery bypass grafting procedures

The use of radial artery conduits in coronary artery bypass grafting (CABG) surgery is associated with improved long-term patency and patient survival rates as compared with saphenous vein conduits. Despite increasing popularity, relative incidence of local harvest-site complications and subjective perception of adverse long-term sequelae remain poorly described. To allow for direct comparison, we investigated a consecutive series of patients in whom both the radial artery and the saphenous vein had been harvested for isolated CABG during a 36-month period. Patients were identified from a prospective database that collects baseline clinical information. The patients' own perceptions were assessed by a standardized direct telephone survey regarding any persistent functional impairment from their arm and leg operation sites. Out of 1756 CABG patients during the study period, 168 (10%) were eligible (78% men, median age: 60.1 ± 9.6 years, range: 29.6-82.4 years). Of these, 123 (73%) could be contacted and interviewed at a median follow-up time of 2.5 ± 0.9 years. Surgical wound complications at harvest sites (arms and legs) had occurred in 3% and 12%, respectively, and persistent symptoms (arms and legs) were self-reported as follows: chronic pain (5% and 8%), numbness (32% and 34%) and paresthesia/dysesthesia (14% and 7%). Overall, 39% of the patients reported persistent discomfort at the arm and 39% at the leg. Both sites were simultaneously affected in 21% (P = n.s., paired testing). Logistic regression modeling showed that patients with adverse long-term sequelae were younger (P < 0.005), had a higher body mass index (P < 0.05) and a lower EuroSCORE (P < 0.001) at the time of operation (EuroSCORE, European System for Cardiac Operative Risk Evaluation). Perioperative wound complications, however, did not predict persistence of symptoms. Persistent harvest-site discomfort occurs with astonishing frequency after CABG surgery and affects arms and legs equally. Although usually considered a minor complication, long-term limitation to quality of life may be substantial, particularly in younger and relatively healthy patients. Thus, harvest-site discomfort clearly belongs to the list of possible post-CABG complications of which patients need to be aware.

Radial artery versus saphenous vein conduits for coronary artery bypass surgery: forty years of competition — which conduit offers better patency? A systematic review and meta-analysis

The internal thoracic artery is the most effective conduit for coronary artery bypass surgery; however, most patients have multivessel disease and require additional saphenous vein or radial artery grafts. In this systematic review of the literature and meta-analysis, we aim to compare reported patency rates for these conduits and explore if differences are homogeneous across follow-up intervals. A literature search was performed using Embase, Medline, Cochrane Library, Google Scholar and randomised controlled trial databases to identify studies published between 1965 and October 2009. All studies reporting angiographic comparison of saphenous vein and radial artery conduit patency were included, irrespective of language. The end point was angiographic graft patency stratified over different follow-up intervals. Meta-analysis was performed according to recommendations from the Cochrane Collaboration and Meta-analysis Of Observational Studies in Epidemiology guidelines. We used a random-effect model and the odds ratio as the summary statistic. A total of 35 studies were identified. They reported early patency (≤ 1 year, 6795 grafts), medium-term patency (1-5 years, 3232 grafts) and long-term patency (>5 years, 1157 grafts). Significant variation of comparative patency existed across different follow-up intervals. Early saphenous vein patency was similar to radial artery patency with odds ratio of 1.04 (95% confidence interval 0.68-1.61). Medium-term saphenous vein patency, however, deteriorated significantly (odds ratio 2.06, 95% confidence interval 1.29-3.29). Similarly, long-term patency was better for radial artery conduits (odds ratio 2.28, 95% confidence interval 1.32-3.94). Heterogeneity was due to angiographic patency characteristics and related to risk of bias. In conclusion, the findings of this systematic review of the published literature and meta-analysis support the use of radial artery in preference to saphenous vein conduits for coronary artery bypass surgery.

Predictive Value of IntraoperativeIn SituRadial Artery Conduit Flow Assessment Prior to Harvesting during Coronary Artery Bypass Surgery

Radial artery (RA) is increasingly preferred as the second best conduit in coronary artery bypass grafting (CABG). Harvesting techniques affect the integrity of the RA with implications for the immediate and late outcome. The aim of this study was to describe a simple intra-operative technique that allows the quality of the RA to be assessed prior to its harvesting during CABG. The study group consisted of 54 patients who underwent CABG. A 2-cm vertical incision was made over the nondominant RA pulse. A limited pedicle of the RA was positioned inside the metal cradle of the flexible flow probe. Baseline transit-time ultrasonic flow and pulsatility index (PI) were measured. Average IN SITU RA flow was 18.6 ml/min (range 4-51 ml/min). Of 14 IN SITU RAs, all but three RAs were found to have adequate flow characteristics and were used as conduits. In the three unsuitable RAs, one had complete obliteration and no flow; one had visible calcifications and very low flow and the third one had a weak pulse, low flow and high PI. Routine assessment of IN SITU RA flow characteristics via a 2-cm incision provides useful information about RA conduit quality prior to its formal harvesting during CABG. Despite considerable skepticism about the use of the radial artery due to its vasospastic potential, this technique may increase utilization rates of the RA as a conduit during CABG, in particular in many young diabetic patients.

Radial Artery Conduits Improve Long-Term Survival After Coronary Artery Bypass Grafting

The second best conduit for coronary artery bypass graft surgery (CABG) is unclear. We sought to determine if the use of a second arterial conduit, the radial artery (RA), would improve long-term survival after CABG using the left internal thoracic artery (LITA) and saphenous vein (SV). We compared the 14-year outcomes in propensity-matched patients undergoing isolated, primary CABG using the LITA, RA, and SV versus CABG using the LITA and only SV. In all, 826 patients from each group had similar propensity-matched demographics and multiple variables. The primary endpoint was all-cause mortality obtained using the Social Security Death Index. Perioperative outcomes including in hospital mortality (0.1% for the RA patients and 0.2% for the SV patients) were similar. Kaplan-Meier survival at 1, 5, and 10 years was 98.3%, 93.9%, and 83.1% for the RA group versus 97.2%, 88.7%, and 74.3% for the SV group (log rank, p = 0.0011). Cox proportional hazards models showed a lower all-cause mortality in the RA group (hazard ratio 0.72, confidence interval: 0.56 to 0.92, p = 0.0084). Ten-year survivals showed a 52% increased mortality for the SV patients (25.7%) versus the RA patients (16.9%; p = 0.0011). For symptomatic patients, RA patency was 80.7%, which was not different than the LITA patency rate of 86.4% but was superior to the SV patency rate of 46.7% (p < 0.001). Using the LITA, SV, and a RA conduit for CABG results in significantly improved long-term survival compared with using the LITA and SV. The use of two arterial conduits offers a clear and lasting survival advantage, likely due to the improved patency of RA grafts. We conclude that RA conduits should be more widely utilized during CABG.

Invited Commentary

Invited Commentary

Total Arterial Myocardial Revascularization Using New Composite Graft Techniques for Internal Mammary and/or Radial Arteries Conduits

Total arterial myocardial revascularization (TAMR) is feasible because of the excellent long-term patency of the arterial conduits. We present five new surgical configurations for TAMR. Between December 1998 and July 1999, 34 patients with triple vessel disease underwent TAMR. All patients were in CCS III or IV. Sketelonized internal mammary arteries (IMAs) were used. The surgical techniques for TAMR consisted of Y or T composite grafts constructed between the in situ RIMA and free LIMA graft or radial artery (RA) conduit in three different configurations. Other techniques uses included a T graft constructed between the RA conduit and free LIMA graft in two configurations. Twenty-six (76%) patients underwent contrast-enhanced TTE color Doppler before and after adenosine provocative test, and seven (20%) patients had postoperative coronary angiography. Overall, 144 anastomoses (average number per patient, 4.2) were completed. One (2.9%) patient undergoing an inverted T graft technique died on postoperative day 2. Another patient (2.9%) undergoing the right Y graft technique using IMAs and RA suffered perioperative AMI due to RA conduit vasospasm. Contrast-enhanced TTE color Doppler before and after the adenosine provocative test and at 1 week postoperation revealed a coronary flow reserve (CFR) of 2.1 +/- 0.2 in the LIMA stem, and in the RIMA stem, a CFR of 2.3 +/- 0.3 (P < 0.007). In one patient undergoing the right Y graft technique using IMAs, we found only anomalous flow dynamic parameters of RIMA, suggesting a partial graft closure. The angiographic examination revealed a free LIMA graft closure. At 6 +/- 2.4 months after operation 33 patients were alive and free of angina. The IMAs stem evaluation by TTE color Doppler at follow-up revealed a 2.45 +/- 0.1 mm LIMA diameter and 2.6 +/- 0.2 mm RIMA diameter, which was more than early postoperative data of P < 0.001 and P < 0.007, respectively. These data indicate that TAMR in young patients perhaps offers a better postoperative outcome and perhaps should be part of the surgical armamentarium. These techniques apply the "nontouch" principle and should be taken into consideration in patients with a heavily calcified aorta. Contrast-enhanced TTE color Doppler is a safe, accurate, and noninvasive test, which allows assessment of IMA patency and CFR evaluation. The flow reserve of the IMAs seems to be adequate for multiple coronary anastomoses.

Effects of Trimetazidine on Endothelial Dysfunction After Sheath Injury of Radial Artery

Transradial coronary artery angiography (TRCAG) can have harmful effects on the radial artery as a conduit for coronary artery bypass graft surgery. The aim of this study was to evaluate the effects of trimetazidine (TMZ) on the functional recovery of the radial artery in patients who underwent TRCAG with flow-mediated dilation (FMD). Sixty patients, who underwent TRCAG using a 5Fr sheath were randomly assigned to the TMZ group or the control group. Baseline, post-TRCAG (<24 hours after TRCAG), and 10-week follow-up FMD were performed. In the control group of the cannulated arm, the baseline FMD was 11.4 +/- 3.5%, but the post-TRCAG FMD was significantly decreased to 4.2 +/- 2.9% (p <0.01). At 10-week follow-up, FMD was still decreased compared to baseline FMD (11.4 +/- 3.5% vs 5.9 +/- 3.3%, p <0.01). In the TMZ group of the cannulated arm, the difference in FMD between baseline and post-TRCAG was also significant (11.3 +/- 3.5% vs 6.3 +/- 4.0%, p <0.01). However, at 10-week follow-up, FMD was improved to 10.4 +/- 3.4%, and there was no difference in FMD between baseline and 10-week follow-up (11.3 +/- 3.5% vs 10.4 +/- 3.4%, p = 0.26). Repeated-measures analysis of variance confirmed the significance of the differences in FMD between the TMZ group and the control group (p <0.01). In conclusion, TMZ therapy after TRCAG reduced the endothelial dysfunction of the radial artery. This could contribute to positive effects for the radial artery conduit after coronary artery bypass graft surgery.

Long-Term Patency of 1108 Radial Arterial-Coronary Angiograms Over 10 Years

To avoid late vein graft atheroma and failure, we have used arterial grafts extensively in coronary operations. The radial artery (RA) is the conduit of second choice. This study determined the long-term patency of the RA as a coronary graft. Two independent observers evaluated 1108 consecutive postoperative RA conduit angiograms performed between January 1997 and June 2007 for cardiac symptoms. Mean time to postoperative angiography was 48.3 months (range, 1 to 132 months). An RA graft was considered failed (nonpatent) if there was stenosis exceeding 60%, string sign, or occlusion. Patency was determined over time, by coronary territory grafted and by the degree of native coronary artery stenosis (NCAS). At a mean of 48.3 months, 982 of the 1108 RA grafts (89%) were patent. RA patencies for the left anterior descending were 96% (24 of 25), diagonal/intermediate, 90% (121 of 135); circumflex marginal, 89% (499 of 561); right coronary, 83% (38 of 46); posterior descending, 89% (253 of 286); and left ventricular branch/posterolateral, 86% (47 of 55). Patency was 87.5% (56 of 64) for NCAS of less than 60% compared with 89% (926 of 1044; p = 0.89) for NCAS exceeding 60%. Of 318 RAs in place more than 5 years, 294 (92.5%) were patent, and for 107 RAs in place for more than 7 years, 99 were patent (92.5%). Patency was consistent through each year of the decade. Mechanisms of failure did not involve development of atherosclerosis. Patent RA grafts were smooth, with no angiographic evidence of atheroma. Late patencies of RA grafts are excellent and justify continuing use of the RA in coronary operations.

Sequential Radial Artery Grafts for Multivessel Coronary Artery Bypass Graft Surgery: 10-Year Survival and Angiography Results

Increasing the number of arterial grafts for coronary artery bypass grafting (CABG) has been linked to improved late survival. Currently, it is not known if these long-term benefits are also true when sequential radial artery (RA) grafts are the primary means to maximizing arterial revascularization. We compared late survival of 532 consecutive patients receiving sequential RA grafts (sequential RA group: 438 men; 462 with three-vessel disease) with that of a 4,131 contemporaneous internal thoracic artery (ITA) with saphenous vein (SV) multivessel CABG cohort (conventional group). Graft failure rates were determined from symptom-driven repeat angiography films in 122 sequential RA patients performed 2 to 4,317 days after surgery. Median survival sequential RA follow-up was 5.3 years (range, 0.5 to 12.3). The sequential RA patients received a total of 1,181 RA grafts (538 sequential [30 triple] and 75 single) along with 636 SV and 533 ITA. Overall RA graft failure (80 of 272; 29%) was intermediate to that for ITA (7 of 121; 5.8%; p < 0.001) and vein (54 of 133, 41.6%; p = 0.032) grafts. Sequential versus nonsequential RA failure did not differ (77 of 252 [31%] versus 3 of 20 [15%]; p = 0.202), while failure of the proximal (36 of 123; 29%) and distal (40 of 129; 31%) components of sequential RA grafts were essentially identical. A total of 69 deaths (6 operative; 1.1%) have occurred in the sequential RA cohort. Unadjusted 10-year sequential RA cohort survival was 76.2% overall, and 79.0% for the 454 primary isolated CABG subgroup. The risk-adjusted 10-year survival using a logit propensity score was substantially better for the sequential RA cohort versus the conventional CABG cohort (risk ratio [95% confidence interval] 0.61 [0.44 to 0.85]; p = 0.003). Sequential RA grafting is a safe method for maximizing arterial revascularization and is associated with excellent 10-year survival that seems to be superior to conventional or ITA/SV CABG results. Also, the similar proximal and distal sequential RA patency mitigates concerns of a clinically significant effect of increased vasoreactivity of distal segments of RA conduits.

Letter by Nežić et al Regarding Article, “The Impact of Diabetic Status on Coronary Artery Bypass Graft Patency: Insights From the Radial Artery Patency Study”

HomeCirculationVol. 119, No. 22Letter by Nežić et al Regarding Article, “The Impact of Diabetic Status on Coronary Artery Bypass Graft Patency: Insights From the Radial Artery Patency Study” Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBLetter by Nežić et al Regarding Article, “The Impact of Diabetic Status on Coronary Artery Bypass Graft Patency: Insights From the Radial Artery Patency Study” Duško Nežić, MD, PhD, FETCS, Aleksandar Knežević, MD, BcS, Miomir Jović, MD, PhD and Petar Vuković, MD, BcS Duško NežićDuško Nežić “Dedinje” Cardiovascular Institute, Belgrade, Serbia Search for more papers by this author , Aleksandar KneževićAleksandar Knežević “Dedinje” Cardiovascular Institute, Belgrade, Serbia Search for more papers by this author , Miomir JovićMiomir Jović “Dedinje” Cardiovascular Institute, Belgrade, Serbia Search for more papers by this author and Petar VukovićPetar Vuković “Dedinje” Cardiovascular Institute, Belgrade, Serbia Search for more papers by this author Originally published9 Jun 2009https://doi.org/10.1161/CIRCULATIONAHA.108.832063Circulation. 2009;119:e559To the Editor:We read with great interest the article by Singh and associates1 that was recently published in Circulation. We respect all subsequent analysis arising from an excellent, prospective, randomized basic study presented by Desai and colleagues2 a few years ago that compared the angiographic patency of radial artery (RA) grafts with that of saphenous vein (SV) grafts 1 year after surgery. Although that study demonstrated significantly better angiographic patency of RA conduits compared with SV grafts (occlusion rate of 8.2% for RA conduits versus 13.6% for SV conduits), the existence of a string sign was assigned to 7% of RA grafts and to only 0.9% of SV grafts. Subsequent analysis of those data3 showed that 48.4% (15 out of 31) of the RA conduits with a string sign presented with thrombolysis in myocardial infarction (TIMI) 1 flow. A significantly higher rate of postoperative angina has been registered in patients whose RA conduits were found to have a string sign and TIMI 1 flow.3The primary end point of the study by Singh et al1 was to determine overall study graft failure, and the secondary objective was to compare graft failure of the study RA conduits versus the study SV conduits within nondiabetic and diabetic patients. All RA conduits with a string sign were considered to be patent. In our opinion, if we are discussing the failure and occlusion of study grafts, RA grafts with an angiographic string sign should be included in the category of failed conduits (at least those with TIMI 1 flow because TIMI 1 flow has been defined as some penetration of contrast material beyond the point of obstruction but without perfusion of the distal coronary bed4). Although only the perioperative use of α-adrenergic agonists and target vessels stenosis <90% were pointed out as significant factors for a string sign3 appearance of RA conduits, we assume that RA conduits with a string sign and TIMI 1 flow were similarly distributed among diabetic and nondiabetic patients. Some of the authors’ conclusions are based on the border level of statistical significance (ie, RA protectiveness against graft failure compared with SV grafting in both diabetic and nondiabetic cohorts). It is possible that, with the inclusion of all RA conduits that have definitely failed (36 occluded, 15 with a string sign and TIMI 1 flow), the findings of the study would no longer be statistically significant.DisclosuresNone. References 1 Singh S, Desai N, Petroff S, Deb S, Cohen E, Radhakrishnan S, Schwartz L, Dubbin J, Fremes S, for the Radial Artery Patency Study Investigators. The impact of diabetic status on coronary artery bypass graft patency: insights from the radial artery patency study. Circulation. 2008; 118: S-222–S-225.Google Scholar2 Desai N, Cohen E, Naylor D, Fremes E, for the Radial Artery Patency Study Investigators. A randomized comparison of radial artery and saphenous vein coronary bypass grafts. N Engl J Med. 2004; 351: 2302–2309.CrossrefMedlineGoogle Scholar3 Miwa S, Desai N, Koyama T, Chan E, Cohen E, Fremes S, from the Radial Artery Patency Study Investigators. Radial artery angiographic string sign: clinical consequences and the role of pharmacologic therapy. Ann Thorac Surg. 2006; 81: 112–119.CrossrefMedlineGoogle Scholar4 Appleby MA, Michaels AD, Chen M, Gibson CM. Importance of the TIMI frame count: implications for future trials. Curr Control Trials Cardiovasc Med. 2000; 1: 31–34.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails June 9, 2009Vol 119, Issue 22 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCULATIONAHA.108.832063PMID: 19506121 Originally publishedJune 9, 2009 PDF download Advertisement

Histopathologic changes of the radial artery wall secondary to transradial catheterization

The immediate effects of transradial access on the radial artery wall are unknown. In this study we sought to assess the histological changes induced by catheterization on the radial artery. Thirty-four patients undergoing coronary artery bypass grafting (CABG) had radial arteries harvested to serve as bypass conduits. The proximal and distal ends of the radial artery conduits were sectioned and embedded in paraffin. Both ends of all specimens were evaluated by a blinded pathologist for intimal hyperplasia, medial inflammation, medial calcification, periarterial tissue or fat necrosis, adventitial inflammation, adventitial necrosis, and adventitial neovascularization. Fisher's exact test was used for statistical analysis. Fifteen previously catheterized radial arteries (TRA group) were compared with 19 noncatheterized arteries (NCA group). The distal ends of the TRA group showed significantly more intimal hyperplasia (73.3% vs 21.1%; p = 0.03), periarterial tissue or fat necrosis (26% vs 0%; p = 0.02), and more adventitial inflammation (33.3% vs 0%; p = 0.01) than the distal ends of the NCA group. The distal ends of the TRA group also showed significantly more intimal hyperplasia (73.3% vs 26.6%; p = 0.03) and adventitial inflammation (33.3% vs 0%; p = 0.01) than the proximal ends of the same arteries. There were no histological differences in the proximal ends of the two groups. Transradial catheterization induces significant histological changes suggestive of radial artery injury limited to the puncture site in the form of intimal hyperplasia, medial inflammation, and tissue necrosis. Both the proximal and distal ends of the radial artery show a spectrum of atherosclerotic changes independent of its use for transradial catheterization.