Routine use of unilateral and bilateral radial arteries for coronary artery bypass graft surgery

Using bilateral radial arteries in coronary artery bypass grafting is safe

BACKGROUND

Recent studies have revealed that radial artery grafts have excellent patency rates. However, harvesting of the radial artery is generally limited to the non-dominant forearm. We would like to demonstrate the effectiveness and safety of bilateral radial artery harvesting.

METHODS

We enrolled 173 patients undergoing coronary artery bypass. Bilateral RA were used in 64 cases and unilateral in 109. The primary endpoint was post-harvest forearm and hand complications.

RESULTS

Forearm and hand complications occurred immediately postoperatively in 28.1% of the bilateral radial artery group, significantly more than in the unilateral radial artery group (8.3%). During follow-up, no overall difference was found in post-harvest forearm and hand complications. However, the forearm and hand perception score in the bilateral radial artery group was higher: 8.78 ± 1.45 vs. 8.35 ± 0.84 in the unilateral radial artery group. Subgroup analysis in the bilateral radial artery group revealed no significant difference in forearm and hand perception score between the dominant and non-dominant donor forearms (8.78 ± 1.45 in non-dominant and 8.66 ± 1.00 in dominant forearms). The bilateral radial artery group had more arterial coronary anastomoses, longer operative times, and longer cardiopulmonary bypass times. However, a backward multiple linear regression model revealed that only two factors related to operative time, these were the number of arterial distal coronary anastomosis and cardiopulmonary bypass time.

CONCLUSIONS

This study demonstrated that bilateral radial artery conduits can be used effectively and safely with no difference in persistent complications related to the hands and forearms.

Radial Artery Versus Saphenous Vein Grafts in Coronary Artery Bypass Surgery: a Literature Review

PURPOSE OF REVIEW

Coronary artery bypass grafting is a preferred strategy for complete coronary revascularization in patients who have multi-vessel coronary artery disease, left ventricular dysfunction, and/or diabetes. Both arterial (internal thoracic artery/radial artery) and venous grafts are utilized to bypass the obstruction in native vessels. Despite having radial arterial grafts as a preferred second conduit for bypass, venous grafts are more commonly used.

RECENT FINDINGS

We review the existing literature and report the preferred conduit based on a recently published meta-analysis of 6 randomized controlled trials. The analysis concluded that radial artery grafts are associated with fewer adverse cardiac events and better graft patency at 5 years of follow-up. Although saphenous vein grafting is the most commonly used conduit in addition to ITA, current data suggests that total arterial bypass (using RA conduit in addition to ITA) may be the better strategy. Both the US and European consensus guidelines advocate for the use of arterial over SV grafting for most patients.

A Prospective Randomized Study of Endoscopic Versus Conventional Harvesting of the Radial Artery

OBJECTIVE

The aims of the study were to determine whether endoscopic harvesting of the radial artery (RA) reduces morbidity due to pain, infection, and disability with improvement in satisfaction and cosmesis compared to the conventional technique and (2) to compare the 6-month angiographic patency of the RA harvested conventionally and endoscopically.

METHODS

In a prospective randomized study, 119 patients undergoing coronary artery bypass grafting using the RA were randomized to have RA harvested either conventionally (n = 59) or endoscopically (n = 60).

RESULTS

Radial artery harvest time (open wound time) was significantly reduced in the endoscopic group (36.5 ± 9.4 vs 57.7 ± 9.4 minutes, P < 0.001). Only one patient developed wound infection (1.6%) in the endoscopic group compared with six patients (10.2%), P = 0.061, in the conventional group. Although this was not statistically significant, clinically this was relevant in terms of reduction in postoperative morbidity. Postoperative pain in the arm incision was significantly lower in the endoscopic group at postoperative day 2 (P < 0.001) and at discharge (P < 0.001) and similar to the conventional open group at 6 weeks' follow-up (P = 0.103). Overall patient satisfaction and cosmesis were significantly better in the endoscopic group at postoperative day 2 (P < 0.001), at discharge (P < 0.001), and at 6 weeks' follow-up (P < 0.001). There was no difference in the arm disability postoperatively (P = 0.505) between the two groups. Six-month angiographic assessment of 23 patients (12 endoscopic and 11 open) revealed no difference in the patency rate (10/12 in endoscopic and 9/11 in open group).

CONCLUSIONS

Endoscopic RA harvesting reduced the incidence of postoperative wound infection and wound pain and improved patient satisfaction and cosmesis compared with conventional harvesting technique. There was no difference in the 6-month angiographic patency of the RA harvested conventionally and endoscopically.

Relaxant effect of the prostacyclin analogue iloprost on isolated human radial artery: An approach for the reversal of graft spasm

Radial artery graft spasm in the perioperative or postoperative period of coronary bypass surgery necessitates urgent treatment due to risk of graft failure and mortality. Herein, we evaluated the effect of iloprost, a prostacyclin (PGI₂) analogue, against the contractions produced by noradrenaline and potassium chloride on isolated human radial artery. Following the determination of endothelial and vascular relaxing capacities of the arteries, iloprost (10^-9M-10^-6M) was cumulatively applied on rings precontracted submaximally with the spasmogens. In some rings, the response to iloprost was assessed following pretreatment with nitric oxide (NO) synthase inhibitor, l-NAME (3×10^-4M,30min). Iloprost produced complete relaxations on radial artery rings precontracted with noradrenaline whereas, only moderate relaxations against the contractions induced by potassium chloride. Notably, the relaxation to iloprost was remarkably blunted in radial arteries with impaired endothelial function. Moreover, the relaxation to iloprost was unchanged in rings pretreated with l-NAME. Our results demonstrated that iloprost could be a potent relaxant agent in reversing radial artery spasm, particularly initiated by noradrenaline, possibly acting via an endothelium-mediated mechanism unrelated to NO.

Radial artery as graft for coronary artery bypass surgery: Advantages and disadvantages for its usage focused on structural and biological characteristics

Radial artery (RA) is the most popular arterial graft after the left internal thoracic artery in both low- and high-risk patients undergoing coronary artery bypass grafting. Various arterial grafts such as the right internal thoracic artery, the right gastroepiploic artery, and the inferior epigastric artery have also gained ground over the past 30 years because of the intimal hyperplasia and atherosclerosis of the saphenous vein leading to late graft occlusion. In this review article we would like to present the utility of the RA as a graft, focused mainly on its structural and biological characteristics.

Arterial grafts: clinical classification and pharmacological management

In comparison with standard saphenous vein grafts, use of the internal mammary artery (IMA) as a coronary artery bypass graft has achieved superior long-term results. This is related to the differences in the biological characteristics between the venous and arterial grafts. However, even arterial grafts are not uniform in their biological characteristics. The variation in the perioperative behavior of the grafts and in their long-term patency may be related to different characteristics. These factors should be taken into account in the use of arterial grafts, some of which are subjected to more active pharmacological intervention during and after the operation to obtain satisfactory results. To better understand the biological behavior of the grafts, their common features and their differences, a clinical classification may be useful for a practicing surgeon. Based on experimental studies of their vasoreactivity combined with anatomical, physiological and embryological considerations, we have proposed a functional classification for arterial grafts that may be useful clinically. Our classification suggests that there are three types of arterial grafts: Type I-somatic arteries; Type II-splanchnic arteries; and Type III-limb arteries. Type I arteries have enhanced endothelial function and release more nitric oxide and other relaxing factors. Type II arteries, such as the gastro-epiploic artery, and Type III arteries, such as the radial artery (RA), have higher pharmacological reactivity to vasoconstrictors. This classification explains why the IMA has the best long-term patency. Because Type II and III arteries are prone to spasms due to higher contractility, they require more active pharmacological interventions. Furthermore, the harvesting technique of the conduits, including the saphenous vein and IMA, are described and discussed in this article. Prevention of spasms using two cocktails of medications (verapamil + nitroglycerin and nicardipine + nitroglycerin) during harvesting of the conduits is described. These solutions have been demonstrated to be clinically effective.

Transcarpal cardiac catheterization

INTRODUCTION

Even though the performance of coronary diagnostic and therapeutic procedures through the distal forearm arteries has become a well-established practice, only a small minority of procedures employ transcarpal approach. The aim of this review is to describe the state of art in cardiac catheterization through distal forearm arteries, to point out the advantages and disadvantages of this approach, and to discuss the specific aspects in which it differs from the transfemoral approach.

METHODS

A Medline search up to January 2009 and the articles retrieved were selectively evaluated. Practical recommendations are given based on the authors' experience.

RESULTS

The following advantages of the transcarpal approach to the coronary arteries, as compared to the transfemoral approach, were evident in 23 prospective randomized studies and registries: a lower risk of complications at the site of access (0.05% and 0.3% versus 2.3% and 2.8%), lower mortality (2.8% versus 3.9%), greater patient comfort, lower cost (14% and 15% lower), and a shorter hospital stay (1.5 days and 3 days versus 1.8 days and 4.5 days). Its disadvantages include the potential need for conversion to a transfemoral procedure, higher radiation exposure of the physician, and an extended learning curve, so that procedure times are longer and rates of technical failure are higher until about 400 procedures have been performed.

CONCLUSIONS

The current data give a favorable view of this procedure as long as its specific requirements in terms of pretreatment, choice of materials, technique, post-procedural care, and expertise of the physician are taken into account.

Retrospective analysis of local sensorimotor deficits after radial artery harvesting for coronary artery bypass grafting

OBJECTIVES

The radial artery (RA) has gained widespread acceptance as a conduit for coronary artery bypass. We analyze patient-based data to determine risk factors for long-term upper limb morbidities associated with RA harvest for coronary artery bypass grafting.

STUDY DESIGN/METHODS

Between April 1997 and March 2004, a total of 1030 patients underwent RA harvesting for coronary artery bypass grafting for a total of 1704 harvest sites. Patients were contacted by telephone and asked to report any ongoing severe sensory and functional motor deficits for each harvest site since surgery. Retrospective chart review was performed and preoperative risk factors were evaluated. Patient-based risk factors were evaluated for development of significant long-term local sensorimotor deficits including gender, elderly age (>70 y), diabetes, smoking, and whether the RA was harvested from the dominant hand.

RESULTS

Successful evaluation of 629 patients for a total of 1048 RA harvest sites was completed. The mean follow-up time was 48.3 mo (range, 2 to 86 mo). The mean age of the patients analyzed was 62.2 y. On statistical analysis, diabetics and elderly did not report significantly greater functional or sensory deficits than nondiabetics and nonelderly, respectively. There was a significantly higher incidence of sensory deficits in smokers compared with nonsmoker patients (4.2% versus 1.4%; P = 0.005) but no difference in their functional impairment was noted. Harvesting from the dominant hand did not influence the occurrence of sensory or motor functional deficits.

CONCLUSIONS

RA harvesting for coronary artery bypass grafting can be done with minimal serious long-term upper limb morbidity in higher risk patients. Based on our findings, harvesting of the RA from the dominant hand is not contraindicated in these patients.

Intraindividual comparison of human radial and internal thoracic arteries in vitro and the effect of preoperative calcium blocker therapy

The patency rate of radial artery (RA) conduits is considerably lower than that of internal thoracic artery (ITA) grafts and the evidence suggests that this is due to a clinically suspected higher incidence of vasospasm. The aim of this study was, therefore, to compare intraindividually the pharmacological reactivity of RA with that of ITA. Both RA and ITA were taken from the same patients and investigated in parallel. Changes in tone were monitored isometrically on ring preparations from both arteries in organ baths with modified Krebs-Henseleit solution containing 1.25 mm calcium chloride at 1 g passive preload. In intraindividual comparisons maximal receptor-mediated contractile responses to noradrenaline and endothelin-1 and endothelium-dependent acetylcholine-induced relaxant responses revealed no differences between both arteries. By contrast, depolarization-induced contractions to potassium chloride (KCl) appeared to be significantly higher in RA than in ITA. Further analysis, however, revealed that this difference was due to preoperative calcium entry blocker (Ca(2+)eB) therapy. Compared with control tissues, maximal responses to KCl were significantly attenuated in the ITA but unchanged in RA when arteries were obtained from patients with preoperative Ca(2+)eB therapy. The present results suggested that functional responses to pharmacological stimuli of both RA and ITA were quite similar. Preoperative Ca(2+)eB therapy, however, attenuated markedly responses to KCl of the ITA leaving those of RA unchanged. These results, demonstrating a lower sensitivity to Ca(2+)eB of RA, therefore suggested that in addition to Ca(2+)eB other classes of drug may be more effective at reducing the propensity of RA conduits to vasospasm.

Efficacy of Physiologic Temperature on the Spasm of Harvested Radial Artery

BACKGROUND

The potential disadvantage of using the radial artery for coronary artery bypass grafting is its increased tendency to vasospasm. Therefore, different antispastic agents are being used in the perioperative and postoperative period. During the preparation of the radial artery, normal local and systemic temperatures are lost.

METHODS

We investigated the effects of topical normal saline solution at 20 degrees C (group SI), normal saline solution at 36 degrees C (group SII), diltiazem at 20 degrees C (group DI), and diltiazem at 36 degrees C (group DII) on radial artery free flow. Each group contained 10 patients undergoing coronary bypass surgery. Free flow and local temperature were measured at 3 stages: after the exploration and preparation of the distal 3 cm of the radial artery, after total preparation of the radial artery, and a median of 12 minutes after the pedicle had been sprayed with one of the agents.

RESULTS

Parallel to the significant decrease of the second local temperatures (P < .001), the second flow of the 4 groups decreased significantly (P < .001).

CONCLUSION

Hypothermia plays an important role in radial artery vasospasm, and normothermia may be the best perioperative vasodilating agent since the normal radial artery flows were reached with normothermia.

Harvesting radial artery and neurologic complications

BACKGROUND

Determination of the incidence, mechanisms, and diagnosis of hand complications after radial artery (RA) harvesting in coronary surgery (CABG).

METHODS

The study group (RA group) includes 54 patients who underwent RA harvesting in CABG operation. The control group (noRA group) consists of 131 patients who underwent CABG without the use of RA graft. The average follow-up time was 16.36 +/- 5.13 months. The patients were examined clinically, (a) for motor function abnormalities associated with radial and median nerve damage and (b) for sensory abnormalities, and the function of radial nerve was determined by eliciting the brachioradialis reflex. They answered in a formal scripted questionnaire to elicit symptoms and clinical points attributable to nerve damage during RA harvest, such as hand weakness, thumb weakness, sensation abnormalities on the back and on the palm side of the forearm, hand numbness, hand-reversible paresis or forearm infection postoperatively, and any other upper limb abnormality.

RESULTS

Of the patients in the RA group, 34.09% reported left-hand abnormality after operation. On the other hand, in the noRA group left-hand abnormality was reported in 18.68% of patients. In the RA group sensation abnormality was reported in 34.09% of patients and thumb weakness alone was reported in 6.82% of patients. There was a statistically significant difference between the two groups. Low EuroSCORE was the predicting factor for motor abnormalities.

CONCLUSIONS

More knowledge has been added about the neurologic complications after RA harvesting lately. We demonstrated the rate of motor and sensory abnormality, the potential mechanisms of these complications caused by surgical trauma or devascularization, and any predictive factors of complications. Optimal surgical techniques to avoid the damage of the responsible nerves are recommended.

Extrafascially harvested radial artery in CABG: technique of harvest, complications, and mid-term angiographic patency

BACKGROUND

The initial use of radial artery (RA) for myocardial revascularization was abandoned due to high incidence of early occlusion. The revival of radial artery graft use was attributable to the improved harvesting techniques as well as the introduction of antispasm prophylaxis by calcium channel blockers. Various techniques of harvesting RA have been described and extrafascial harvest is one of the techniques to minimize trauma during harvest. The immediate arm complications and mid-term angiographic patency of the radial artery grafts harvested using extrafascial no-touch technique and used as a conduit for myocardial revascularization were not documented well in the literature.

METHODS

Between January 1997 and February 2003, 385 patients were operated for coronary artery bypass grafting using radial artery graft as one of the conduits. We used extrafascial no-touch technique and a coagulation current cautery at a strength of 10 to 15 W to control the bleeding during the blunt dissection of the radial artery. The complications related to the radial artery harvest were prospectively recorded and analyzed. This conduit was used as a free graft in 272 patients, left internal mammary artery and radial artery Y graft in 61 patients, Right internal mammary artery, and radial artery composite in situ graft in 52 patients. The radial artery donor arm in these patients was evaluated for complications. Angiographic evaluation of the radial artery graft was carried out randomly in 51 patients and angiography was done after an interval of 6 to 72 months (mean 29.55 +/- 21.77 months).

RESULTS

In two patients, although the preoperative Allen test was negative, the radial artery was not harvested after completion of the dissection and was left in situ because the pulse could not be felt in the radial artery distal to the clamp after trial occlusion of the mid part of RA. The arm complications noticed were cutaneous parasthesias in 9 patients (2.33%), which subsided in 4 weeks, stitch abscess and superficial wound infection in 4 patients (1.03%), hematoma/seroma treated with drainage in outpatient department in 3 patients (0.78%), and wound infection requiring open drainage in an operating room in one patient (0.76%). Angiographically radial artery was patent in 48 of 51 patients (94.11%).

CONCLUSIONS

The extrafascial technique of radial artery harvest is safe and an easily reproducible method with minimal arm complications and good mid-term clinical and angiographic results. The mid-term angiographic patency rates of RA harvested using this technique are comparable to that of the published results of intrafascially harvested radial artery grafts and left internal mammary artery grafts.

Endoscopic Radial Artery Harvest for Coronary Artery Bypass Surgery

BACKGROUND/PURPOSE

Coronary artery bypass grafting (CABG) provides better long-term patency than percutaneous intervention in patients with significant coronary artery disease. The radial artery is the second most common arterial conduit used for CABG in Western countries. However, radial artery harvesting necessitates a large surgical wound and has gained few patients' acceptance in subtropical areas. This study investigated the use of the minimally invasive approach of endoscopic radial artery harvest for CABG, and the surgical results at the harvest site.

METHODS

An endoscopic harvest program for radial arteries was implemented in this hospital in September 2003. During the first 12 months of the program until September 2004, 122 patients underwent the procedure. Preoperative evaluation included Allen's test and the modified palmar arch perfusion test. The age of patients ranged from 32 to 88 years old. Patients were excluded from participation if they had undergone recent transradial catheterization, had end-stage renal disease or documented peripheral artery occlusive disease. The VasoView system was utilized for the procedure. Details of the surgical techniques used were recorded and analyzed.

RESULTS

Using the endoscopic technique, 122 radial arteries were harvested successfully. The mean resting length of the harvested radial artery was 15.7 cm. No obvious arterial injury was visually confirmed. All radial arteries were used for CABG, except for two which were noted to have atherosclerotic plaques causing stenoses. Forty-seven patients presented with mild numbness over the dorsum of the thumb base, which improved significantly during the 3-month follow-up. No arterial insufficiency in the forearms or hands was noted.

CONCLUSION

Endoscopic harvest of the radial artery is technically demanding, but excellent results can be achieved. The endoscopic approach can provide suitable conduits in a less invasive way than the open harvest technique.

Comparative Effects of Tolazoline and Nitroprusside on Human Isolated Radial Artery

BACKGROUND

The radial artery is increasingly being used in coronary revascularization as an alternative conduit to a saphenous vein graft. Its perfect endothelial capacity provides a high patency rate comparable with the internal mammary artery (IMA). However, its spastic characteristics cause difficulties during its intraoperative preparation and may lead to early postoperative graft failure. Thus, treatment and/or prevention of radial artery spasm with an effective vasodilator agent is essential for its longevity. Endogenous vasoconstrictors, including noradrenaline, endothelin-1, and thromboxane A2, are likely to play a role in the pathogenesis of graft spasm. In the present study, we evaluated the vasorelaxant effect of tolazoline, a nonselective alpha-adrenoceptor blocker, against the contractions induced by various spasmogenic agents in an isolated human radial artery.

METHODS

Tolazoline (10(-9)-10(-4) M) or sodium nitroprusside (SNP, 10(-9)-10(-4) M) were cumulatively applied on radial artery rings precontracted submaximally with noradrenaline, endothelin-1, thromboxane analogue, U46619, or potassium chloride. In addition, some rings were pretreated with tolazoline (4 x 10(-6) M) for 30 minutes and the contractile response curve to noradrenaline was assessed in its presence.

RESULTS

Tolazoline effectively reversed noradrenaline-induced contractions in the radial artery, whereas it failed to produce remarkable relaxations on rings contracted with other spasmogenic agents, while SNP overcame the contractions induced by all spasmogens to a similar extent. In addition, brief pretreatment of radial artery rings with tolazoline significantly inhibited the contractions to noradrenaline.

CONCLUSIONS

Tolazoline is not as broadly effective as SNP against all spasmogens investigated; however, it may be effective in counteracting alpha-adrenoceptor-mediated vasospasm in human radial arteries.

Radial Artery Graft for Coronary Artery Bypass Surgery: Biological Characteristics and Clinical Outcome

The radial artery (RA) is gaining popularity as a bypass conduit for coronary artery bypass grafting, and its impact on clinical practice has been extensively explored. In the present article, we provide a review of postoperative hand circulation, vascular biological characteristics of the RA graft, the efficacy of vasodilator therapies, and mid-term clinical results of use of the RA graft. Fundamental studies revealed excellent vascular biological characteristics of the RA graft as a living arterial conduit, making it almost equivalent to the internal thoracic artery (ITA) graft. Clinical studies have yielded encouraging mid-term results. Most studies reported in favor of the RA graft over the saphenous vein graft with regard to patency rate, freedom from cardiac events, and survival. However, superiority of either the RA or right ITA graft has not been conclusively determined. The long-term results of RA grafts remain unknown, but at present, supplementary use of an RA graft with a left ITA graft appears feasible for CABG.

Transulnar versus transradial artery approach for coronary angioplasty: The PCVI-CUBA study

OBJECTIVES

To compare in terms of efficacy and safety the transulnar to the transradial approach for coronary angiography and angioplasty.

BACKGROUND

Opposite to the transradial approach, which is now widely used in catheterization laboratories worldwide, the ulnar artery approach is rarely used for cardiac catheterization.

METHODS

Diagnostic coronarography, followed or not by angioplasty, was performed by transulnar or transradial approach, chosen at random. A positive (normal) direct or reverse Allen's test was required before tempting the radial or the ulnar approach, respectively. MACE were recorded till 1-month follow-up. Doppler ultrasound assessment of the forearm vessels was scheduled for all the angioplastied patients.

RESULTS

Successful access was obtained in 93.1% of patients in the ulnar group (n = 216), and in 95.5% of patients in the radial group (n = 215), P = NS. One hundred and three and 105 angioplasty procedures were performed in 94 and 95 patients in ulnar and radial group, with success in 95.2% and 96.2% of procedures in ulnar and radial group, respectively (P = NS). Freedom from MACE at 1-month follow-up was observed in 93 patients in both groups (97.8% for ulnar group and 95.8% for radial group), P = NS. Asymptomatic access site artery occlusion occurred in 5.7% of patients after transulnar and in 4.7% of patients after transradial angioplasty. A big forearm hematoma, and a little A-V fistula were observed, each in one patient, in the ulnar group.

CONCLUSION

The transulnar approach for diagnostic and therapeutic coronary interventions is a safe and effective alternative to the transradial approach, as both techniques share a high success rate and an extremely low incidence of entry site complications. The transulnar approach has the potential to spare injury to the radial artery in anticipation of its use as a coronary bypass conduit.

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

BACKGROUND

The purpose of this research was to investigate the in vivo morphofunctional changes induced in the radial artery (RA) by its use as coronary artery bypass conduit by comparing the morphological features and vasoreactivity of the native RA versus the coronary RA graft in the same patient.

METHODS AND RESULTS

Ten years after surgery, 10 patients were submitted to intravascular ultrasound examination of the RA graft of the controlateral (in situ) RA and of the internal thoracic artery (ITA) graft and to vasoactive challenges with acetylcholine and serotonin. Quantitative angiographic assessment showed that the mean diameter of the RA coronary grafts was significantly larger than that of the in situ RA and of the ITA (2.89+/-0.40 mm RA grafts, 2.14+/-0.52 mm in situ RA, 2.25+/-0.53 mm ITA grafts; P<0.001). The in situ RA demonstrated a typical muscular architecture, whereas RA coronary grafts showed a clear reduction of the thickness of the medial layer and had a less well-defined muscular component of the media with interposition of elastic tissue. Serotonin endovascular infusion elicited a strong spastic reaction in in situ RAs; the same challenge induced only moderate constriction in RA and ITA coronary grafts.

CONCLUSIONS

Implantation in the coronary circulation leads to major anatomic and vasoreactive modifications of the RAs that tend to lose the morphofunctional features of a muscular conduit and assume those of an elastomuscular artery, such as the ITA.

Midterm Angiographic Patency and Vasoreactive Profile of Proximal Versus Distal Radial Artery Grafts

BACKGROUND

No data are available on the different angiographic results and the in vivo vasoreactivity of radial artery (RA) grafts obtained from different parts of the conduit, although it is known that the distal segment of the artery has a more pronounced muscular component. This study was conceived to evaluate the angiographic patency and tendency to spasm of proximal versus distal RA grafts.

METHODS

In 29 patients, at the time of surgical myocardial revascularization, the radial artery was divided into two separate conduits, so that these patients received a total of 58 radial grafts (29 from the proximal and 29 from the distal portion of the artery). All cases were submitted to midterm angiography and vasoactive challenges to verify angiographic patency and vasoreactive profile.

RESULTS

Radial artery patency rate was 28 of 29 for both groups. Nine cases of string sign were reported, all in the distal series (p = 0.001). The perfect patency rate of distal grafts was markedly lower than that of proximal grafts (19 of 29 versus 27 of 29; p = 0.02). Vasoactive challenges testified to a higher vasospastic attitude of distal grafts.

CONCLUSIONS

Radial artery grafts obtained from the distal portion of the artery have a higher vasospastic tendency, greater incidence of string sign, and lower midterm perfect patency rate than graft taken from the more proximal part of the artery. The proximal part of the RA should be preferred for use as a conduit for surgical myocardial revascularization.

Role of Radial Artery Graft in Coronary Artery Bypass Grafting

The use of the radial artery (RA) as a coronary artery bypass graft has assumed a revival and thus a multitude of issues have arisen surrounding the routine and widespread use of this conduit in myocardial revascularization. There has been no uniformity regarding harvest techniques, assessment of the adequacy of hand collateral circulation, antispasm protocols, selection of target vessels, and the site of proximal anastomosis. It is widely believed and practiced that the RA should be harvested as a pedicle graft and preferably be used to bypass critically stenosed (>70% stenosis) coronary arteries. It is used either as a free graft with proximal anastomosis to the ascending aorta or as a composite arterial graft along with the left or right internal thoracic artery. The patency of RA grafts depends on the severity of the target coronary artery stenosis and target artery location rather than its use as an aortocoronary conduit or composite graft. In this article, we reviewed the current knowledge regarding the use of RA grafts as a coronary bypass conduit in an attempt to suggest a few acceptable strategies concerning the above issues in a given clinical scenario.

Effects of the Postoperative Administration of Diltiazem on Renal Function After Coronary Artery Bypass Grafting

BACKGROUND

Radial artery grafts are used for coronary artery bypass grafting (CABG), and postoperative antispasm therapy with diltiazem is performed widely. Some investigators have warned that diltiazem administration after cardiac surgery is harmful to renal function. We designed a retrospective study to investigate the renal and hemodynamic effects of the postoperative administration of diltiazem in patients undergoing CABG.

METHODS

Subjects were 90 consecutive CABG patients. All were treated with diltiazem during surgery (a 0.1 mg/kg bolus injection followed by continuous infusion at 2 microg x kg(-1) x min(-1)). In the 50 patients (diltiazem group) with a radial artery graft, intravenous diltiazem administration was continued until the oral intake of diltiazem (90 mg/d) was begun to avoid graft spasms. In the remaining 40 patients without a radial artery graft, diltiazem was not continued postoperatively (control group). Postoperative renal function, assessed by serum creatinine level and creatinine clearance, and hemodynamic variables (heart rate, arterial pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index) was compared between the two groups.

RESULTS

Renal function: Serum creatinine concentrations on postoperative days 1 through 7 were lower, and the endogenous creatinine clearance in the early postoperative period was higher in diltiazem group than in control group, although the differences were not significant. Hemodynamics: Heart rate was lower in diltiazem group than in the control group, but blood pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index, and urinary output were similar between the groups.

CONCLUSIONS

Our results confirmed that intravenous diltiazem treatment in patients undergoing CABG is not harmful to renal function.

Is postoperative calcium channel blocker therapy needed in patients with radial artery grafts?

BACKGROUND

Chronic calcium channel blocker therapy has traditionally been considered necessary in patients carrying a radial artery graft, even in the absence of objective data to support it. This report was conceived to evaluate the angiographic and clinical effects of calcium channel blocker therapy during the first postoperative year.

PATIENTS AND RESULTS

A total of 100 consecutive patients who received a radial artery graft at our institution were randomly assigned to receive (n = 53) or not receive (n = 47) calcium channel blocker therapy with oral diltiazem 120 mg/daily started in the early postoperative period. At 1-year follow-up, all patients were reassessed clinically and by Tl 201 myocardial scintigraphy, and 83 of them underwent control angiography. In 12 cases we also evaluated the response of the radial artery to the endovascular infusion of serotonin. No difference in terms of clinical outcome, scintigraphic results, and patency rate was found between patients who received or did not receive calcium channel blocker therapy. Endovascular serotonin infusion evoked an evident spastic reaction of radial artery grafts, not attenuated by calcium channel blocker therapy.

CONCLUSION

Calcium channel blocker therapy started immediately after surgery and continued for the first postoperative year does not affect radial artery graft patency and clinical and scintigraphic outcomes. On the basis of these data, the prophylactic use of calcium channel blocker therapy in patients with radial artery grafts seems unsubstantiated.

Intravascular Ultrasound Analysis of the Radial Artery for Coronary Artery Bypass Grafting

BACKGROUND

The radial artery has become a popular conduit for coronary artery bypass surgery. However, limited information has been provided regarding the atherosclerotic nature of this artery, which may affect both the immediate intraoperative difficulties and long-term graft patency.

METHODS

We examined intravascular ultrasound (IVUS) images of the radial artery in patients with coronary artery diseases. Cross sections of the radial artery were assessed using the following factors: lumen diameter, lumen area, vessel diameter, vessel area, plaque area, percent plaque area, and extent of calcium deposition.

RESULTS

The IVUS images were obtained from radial arteries of 58 patients (47 men, average 67 +/- 9 years) during transradial procedures; ie, transradial coronary angiography and/or transradial coronary intervention. Mean luminal diameter was 3.28 +/- 0.69 mm and 3.00 +/- 0.70 mm at the proximal and distal segments, respectively, and 2.58 +/- 0.73 mm at the minimal lumen cross section. A percent plaque area greater than 50% was seen in five radial arteries (8.6%) whose average plaque length was 26.4 +/- 30.8 mm. Of these, one showed a plaque length greater than 50 mm, and another showed vessel caliber less than 2.0 mm. Five of 58 radial arteries (8.6%) showed calcium deposition, two of which showed diffuse calcification (> 50 mm). Thus, among 58 radial arteries, four (6.9%: one with diffuse arteriosclerosis, one small radial artery, two with diffuse calcification) were considered unsuitable for bypass conduit.

CONCLUSIONS

Preoperative evaluation of the radial artery is recommended in order to prevent unnecessary exploration of the forearm and to improve graft patency.

Digital blood flow after radial artery harvest for coronary artery bypass grafting

BACKGROUND

Despite widespread use of radial artery as a bypass conduit in coronary artery bypass surgery, flow readjustment that takes place in the hands and fingers after the removal of the radial artery is poorly understood.

METHODS

Using pulse volume recording plethysmography, a semiquantitative measurement of digital blood flow was carried out in 24 patients 7 days after harvesting of radial artery for coronary artery bypass grafting. Measurements taken from the fingers of the operated arms were evaluated and compared with those taken from the opposite or the control arms.

RESULTS

Postoperatively, there was an overall decrease in blood flow to all the fingers of the operated arms. At the same time, there was evidence of redistribution of digital blood flow favoring the first two fingers over the last two, the same distribution pattern as seen in the fingers of the control arms. The pulse amplitude studies, likewise, showed a significant drop in all fingers of the operated arms, with the decrease most pronounced in the fourth and fifth fingers. None of the patients showed signs of digital ischemia postoperatively.

CONCLUSIONS

The study showed that there was an overall decrease in digital blood flow after radial artery harvesting. The resulting blood supply by way of the remaining ulnar artery still provided more flow to the first two fingers over the last two fingers, indicating the existence of an autoregulatory mechanism operating to satisfy the physiologic needs of the fingers.

Pharmacological assessment of composite arterial conduits using angiography early in the postoperative period

OBJECTIVES

Muscular arteries are vulnerable to vasospasm unlike elastic arteries. Having developed experimental models of composite arterial grafts, we assessed and compared the responses of the grafts with different pharmacological agents using angiography early in the postoperative period.

SUBJECTS AND METHODS

We harvested the internal thoracic artery (ITA) and brachial-median artery (BMA) from 10 sheep. BMA was used as an alternative to the radial artery. Each vessel was assessed histologically and morphologically. Then, a serial composite graft was constructed so that BMA was interposed. On postoperative day one or two, angiography was performed on the composite graft to measure the diameter of each vessel in response to phenylephrine (alpha-adrenergic receptor agonist), nitroglycerin+phenylephrine, and milrinone+phenylephrine.

RESULTS

The BMA had a wide media layer which consisted of abundant smooth muscle cells. The combined intima and media were thicker in BMA than in ITA (p<0.01). After injection of phenylephrine, the BMA diameter decreased (2.5+/-0.4 mm to 1.9+/-0.3 mm, p<0.01), while the ITA diameter remained unchanged (3.7+/-0.2 mm to 3.6+/-0.2 mm). Continuous infusion of nitroglycerin or milrinone prevented phenylephrine-induced vasoconstriction of the BMA (p<0.05).

CONCLUSIONS

These results suggest that muscular arteries have a more pronounced vasoconstrictive response to alpha-adrenergic receptor agonists than the elastic arteries. To avoid potential decrease in graft flow of muscular artery, it is advisable to use a vasodilator nitroglycerin or milrinone early in the postoperative period.

Radial artery patency: are aortocoronary conduits superior to composite grafting?

BACKGROUND

The radial artery (RA) can be used as either an aortocoronary (RA-Ao) or composite graft (T graft). Optimum use for the RA has yet to be established. We compared RA patency with these two techniques.

METHODS

Between October 1993 and June 2001, 1505 patients underwent coronary artery bypass grafting using the RA as either a composite (n = 1022) or RA-Ao graft (n = 483). Angiograms performed on 203 (13.5%) patients with signs or symptoms of ischemia at an average of 26.1 +/- 18.5 months postoperatively were reviewed.

RESULTS

Patients with RA-Ao grafts had a greater incidence of postoperative angiography versus patients with composite grafts (19% versus 11%; p < 0.01). Patients receiving T grafts had a greater number of anastomoses per patient (4.1 +/- 0.6 versus 3.0 +/- 1.0; p < 0.01) and a higher incidence of total arterial revascularization (100% versus 41%; p < 0.01). Regardless of grafting strategy, patency was significantly worse for targets of the right coronary artery (58% T graft; 67% RA-Ao; p < 0.01 for both) and for targets with less than or equal to 70% stenosis (59% T graft; 57% RA-Ao; p < 0.01 for both). The site of proximal anastomosis failed to effect RA patency (relative risk, 1.2; 95% confidence interval, 0.7 to 1.8; p = 0.50).

CONCLUSIONS

The site of the proximal anastomosis does not appear to influence patency. Both RA-Ao and composite conduits are sensitive to target location and stenosis. Advantages of composite grafting include greater conduit length and minimizing aortic manipulation at the expense of increased complexity and the potential for hypoperfusion. These factors should be considered when choosing an RA grafting strategy.

Pretreatment with phenoxybenzamine attenuates the radial artery's vasoconstrictor response to α-adrenergic stimuli

BACKGROUND

Although the radial artery bypass conduit has excellent intermediate-term patency, it has a proclivity to vasospasm. We tested the hypothesis that brief pretreatment of a radial artery graft with the irreversible adrenergic antagonist phenoxybenzamine attenuates the vasoconstrictor response to the vasopressors phenylephrine and norepinephrine compared with the currently used papaverine/lidocaine.

METHODS

Segments of human radial artery grafts were obtained after a 30-minute intraoperative pretreatment with a solution containing 20 mL of heparinized blood, 0.4 mL of papaverine (30 mg/mL), and 1.6 mL of lidocaine (1%). The segments were transported to the laboratory and placed into a bath containing Krebs-Henseleit solution and 10, 100, or 1000 micromol/L phenoxybenzamine or vehicle. The segments were tested in organ chambers for contractile responses to increasing concentrations of phenylephrine and norepinephrine (0.5-15 micromol/L).

RESULTS

Contractile responses to 15 micromol/L phenylephrine in control radial artery segments averaged 44.2% +/- 9.1% of the maximal contractile response to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated contraction to 15 micromol/L phenylephrine (32.1% +/- 5.9%; P =.22), but 1000 micromol/L phenoxybenzamine completely abolished radial artery contraction (-7.2% +/- 4.4%; P <.001). The effect of 10 and 100 micromol/L phenoxybenzamine on attenuating vasocontraction was intermediate between 1000 micromol/L phenoxybenzamine and papaverine/lidocaine. Responses to 15 micromol/L norepinephrine in control radial artery segments averaged 54.7% +/- 7.5% of maximal contraction to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated the contraction response of radial artery segments (35.6% +/- 5.1%; P =.04). In contrast, 1000 micromol/L phenoxybenzamine showed the greatest attenuation of norepinephrine-induced contraction (-10.5% +/- 2.0%; P <.001).

CONCLUSIONS

A brief pretreatment of the human radial artery bypass conduit with 1000 micromol/L phenoxybenzamine completely attenuates the vasoconstrictor responses to the widely used vasopressors norepinephrine and phenylephrine. Papaverine/lidocaine alone did not block vasoconstriction to these alpha-adrenergic agonists.

Long-term results of the radial artery used for myocardial revascularization

BACKGROUND

No information is available on the long-term results of radial artery (RA) grafts used as coronary artery bypass conduits.

METHODS AND RESULTS

In this report, we describe the long-term (105+/-9 months) angiographic results of a series of 90 consecutive patients in whom the RA was used as a coronary artery bypass conduit directly anastomosed to the ascending aorta. The long-term patency and perfect patency rates of the RA were 91.6% and 88%, respectively, versus 97.5% and 96.3% for internal thoracic artery grafts. The severity of stenosis of the target vessel clearly influenced long-term RA patency, whereas location of the target vessel and long-term use of calcium channel blockers did not influence angiographic results. Preserved endothelial function and absence of flow-limiting, fibrous, intimal hyperplasia were also documented.

CONCLUSIONS

Ten years after surgery, RA grafts have excellent patency and perfect patency rates. Appropriate surgical technique and correct indication are the key factors for long-term RA patency.

Percutaneous interventions in radial artery grafts: clinical and angiographic outcomes

In the modern era, radial artery graft is being used with increasing frequency to replace saphenous vein as a conduit for coronary artery bypass surgery. Several reports have shown encouraging early results of radial grafts compared to saphenous grafts. Despite these advantages, radial artery graft failure requiring revascularization does occur. We report on the clinical, angiographic, and technical characteristics and the follow-up results of 22 patients who underwent percutaneous intervention of radial grafts.

Radial artery patency and clinical outcomes: five-year interim results of a randomized trial

OBJECTIVE

This study was undertaken to compare elective angiographic patency and cardiac event-free survival of the radial artery graft with that of the free right internal thoracic artery or saphenous vein during a 10-year period after primary coronary artery bypass surgery.

METHODS

This prospective, randomized, single-center trial was conducted on two groups of patients undergoing primary coronary artery bypass surgery. In a younger group (group 1, n = 285, <70 years), the radial artery was compared with the free right internal thoracic artery. In an older group (group 2, n = 153, >/=70 years), the radial artery was compared with the saphenous vein. The trial conduit was grafted to the largest available coronary artery other than the left anterior descending coronary artery. Angiography was scheduled at intervals between 0 and 10 years according to a second random assignment. Patients were followed up at yearly intervals to assess clinical outcomes. Clinical outcomes were analyzed on an intent-to-treat basis during the 10-year follow-up with time-related analyses. This interim study reports angiographic and clinical outcome results during the first 5 years.

RESULTS

Graft patency estimates were as follows: 0.95 (95% confidence interval 0.85-0.99) in 39 radial arteries versus 1.0 in 29 right internal thoracic arteries (P =.4) in group 1, and 0.86 (95% confidence interval 0.67-0.99) in 24 radial arteries versus 0.95 (95% confidence interval 0.83-0.99) in 22 saphenous veins (P =.5) in group 2. Cardiac event-free survival estimates were as follows: 0.91 (95% confidence interval 0.76-0.99) for the radial artery versus 0.82 (95% confidence interval 0.63-0.99) for the right internal thoracic artery (P =.7) in group 1, and 0.84 (95% confidence interval 0.64-0.99) for the radial artery versus 0.89 (95% confidence interval 0.72-0.99) for the saphenous vein (P =.9) in group 2.

CONCLUSION

The 5-year interim results do not support the hypothesis that the radial artery has superior patency to or is associated with fewer clinical events than free right internal thoracic artery or saphenous vein grafts.

Radial artery use is safe in patients with moderate to severe left ventricular dysfunction

BACKGROUND

Using radial artery grafts in patients with moderate to severe left ventricular dysfunction (LVD; ejection fraction < 35%) has been discouraged for the fear that postoperative vasopressor support may cause graft spasm and lead to ischemic complications. We, therefore, examined the safety of radial grafts in aortocoronary bypass (ACB) patients with LVD.

METHODS

Data were collected from 5,455 patients who underwent isolated ACB between January 1995 and September 2001. One thousand eight hundred three patients received a radial artery graft (RadACB), and 3,652 patients did not (NoRadACB). Three hundred seven RadACB, and 819 NoRadACB operations were performed in LVD patients. A matched (age, sex, urgency of operation, diabetes, and renal insufficiency) cohort analysis was performed in LVD patients. Univariate and logistic regression analyses were performed in the entire population and the unmatched RadACB and NoRadACB patient subgroups to examine the effect of radial artery use on postoperative death or myocardial infarction rate.

RESULTS

The matched cohort analysis revealed a similar rate of death or myocardial infarction (RadACB, 11 of 242 patients; NoRadACB, 16 of 242 patients; p = 0.32). Left ventricular dysfunction was associated with a higher rate of death or myocardial infarction in both unmatched groups (RadACB, odds ratio, 2.36; 95% confidence interval, 1.38 to 4.58; p = 0.004; NoRadACB, odds ratio, 1.62; 95% confidence interval, 1.18 to 2.24; p < 0.001) and in the entire population (odds ratio, 1.77; 95% confidence interval, 1.32 to 2.35; p = 0.003). An interaction term for patients with LVD and a radial artery graft, which was forced into the logistic regression model for the entire population, was not predictive of death or myocardial infarction (odds ratio, 1.52; 95% confidence interval, 0.75 to 3.10; p = 0.25).

CONCLUSIONS

Left ventricular dysfunction carries similar risk for postoperative death or myocardial infarction in RadACB and NoRadACB patients. The presence of LVD in isolation is not a contraindication to the use of radial grafting.

Can ulnar artery velocity changes be used as a preoperative screening tool for radial artery grafting in coronary artery bypass?

Radial artery harvesting for coronary revascularization may result in digit ischemia if collateral circulation is inadequate. The purpose of this study was to compare changes in ulnar artery flow velocity during radial artery compression (RAC) with changes in first- and second-digit pressures during RAC, a previously validated predictor of digital ischemia. Photoplethysmography was used to measure first- and second-digit arterial pressures before and during RAC on 80 extremities. Color flow duplex imaging was used to measure distal ulnar artery peak systolic velocity before and during RAC. Seventy-eight of eighty extremities had a slight increase in ulnar artery velocity with RAC. There was no correlation between ulnar artery velocity changes and digit pressure changes. Measurement of ulnar artery velocity during RAC is not a useful predictor of digit pressure changes. Measurement of segmental upper extremity pressures with first- and second-digit pressure measurement during radial artery compression should remain the preferred preoperative screening tool for radial artery harvest prior to CABG.

Is vitamin C superior to diltiazem for radial artery vasodilation in patients awaiting coronary artery bypass grafting?

OBJECTIVES

We aimed to measure the vasodilating effects of vitamin C on the radial arteries of healthy subjects and to assess whether vitamin C is superior in this regard to diltiazem, a commonly used vasodilator in coronary artery bypass using radial conduits.

METHODS

In a case-control study (study 1) oral single-dose vitamin C (2 g) was given to 15 healthy nonsmokers and 15 matched otherwise healthy smokers. In a randomized double-blind study (study 2) oral single-dose vitamin C (2 g, n = 15) and diltiazem (180 mg, n = 15) were compared in preoperative patients with coronary artery disease. We examined the dilation of the radial artery with high-resolution ultrasonography and measurement of the lumen surface and color Doppler images of the nondominant radial artery just before and 2 hours after drug administration.

RESULTS

In study 1 both smokers and nonsmokers showed a significant increase in the lumen surface at 2 hours compared with at baseline (P <.001 and P =.013, respectively). The increase was larger in smokers (median, 37.5% vs 14.3%; P =.004). In study 2 both groups showed statistically significant increases in the lumen surface at 2 hours compared with at baseline (P <.001 and P =.008 for vitamin C and diltiazem, respectively). Vitamin C achieved a larger increase than diltiazem (median, 33.3% vs 18.2%; P =.016). In multivariate modeling the increase in lumen surface was independently predicted by use of vitamin C over diltiazem (+21.2%, P =.007), diabetes mellitus (+14.5%, P =.085), increased cholesterol (+26.2%, P =.001), and smoking history (+20.8%, P =.017).

CONCLUSIONS

Vitamin C is a potent acute vasodilator in both smokers and nonsmokers and is superior to diltiazem in preoperative coronary patients who need protection from vasospasm of the radial conduit.

Coronary revascularization in the 21st century. Emphasis on contributions by Japanese surgeons

The first three decades of coronary artery surgery have provided the foundation for the next century of this evolution. It is apparent that a multitude of events including the development of cardioplegia, improving surgical instrumentation, technological advances including endoscopic approaches and computer assisted robotics and biologic discoveries such as the role of the endothelium have provided the underpinnings for improved surgical outcomes. However, the single most important determinant of late results is the type of bypass conduit used for grafting. Thus, use of the left internal thoracic artery (ITA) grafted to the left anterior descending coronary is a more important determinant of survival than is any other factor (progression of coronary artery disease, increased age, poor left ventricular function, diabetes, female gender and off-pump operations). Use of two ITAs provides further benefit and it is likely that three or more arterial conduits will be shown to be advantageous in this regard in due time. Japanese cardiothoracic surgeons have made significant contributions to the continuing evolution of coronary bypass surgery and particularly to the advance of arterial conduits. This report will address those contributions to this evolution.

Effect of target stenosis and location on radial artery graft patency

OBJECTIVE

The purpose of this study was to evaluate the effect of target vessel characteristics on radial artery patency when used as a composite T graft.

METHODS

Between October 1993 and March 2001, 1022 patients underwent coronary bypass with the internal thoracic artery-radial artery composite T graft. Of these, angiography has been performed on 109 patients at a mean 27.1 months (range, 2-70 months) postoperatively for symptoms of ischemia. By means of Cox proportional hazard models, the relationships between anastomotic patency and target vessel location, proximal stenosis, target diameter, and quality were assessed.

RESULTS

A total of 231 radial artery anastomoses were evaluated. The mean stenosis for patent anastomoses was 82% compared with 71% for occluded anastomoses (P <.001). Anastomotic patency for targets with moderate stenosis (< or = 70%) was worse than that for vessels with critical stenosis (> or = 90%; relative risk, 1.7; 95% confidence interval, 1.3-2.2; P <.001). Patency for targets of the right coronary artery was statistically inferior to that for targets of the left anterior descending artery (relative risk, 1.8; 95% confidence interval, 1.2-2.9; P =.01) and bordered on significance versus that for the circumflex artery distribution (relative risk, 1.6; 95% confidence interval, 1.0-2.8; P =.06). When directed toward critically stenosed targets of the left anterior descending or circumflex arteries, radial artery patency was not statistically different that that of the internal thoracic artery (P =.19).

CONCLUSION

Radial artery patency is sensitive to both target location and proximal target stenosis. Selective use of the radial artery to targets of the left anterior descending and circumflex distributions remains encouraging. Radial artery grafts to targets of the right coronary artery or those with moderate stenosis appear to be at particularly high risk of failure.

Endothelin receptors in cultured and native human radial artery smooth muscle

In human vascular smooth muscle cells endothelin-1, acting at both endothelin A and endothelin B receptors, has been demonstrated to be both a potent vasoconstrictor and mitogen. Our aim was to study the functional expression of endothelin receptors in human radial artery smooth muscle using both native tissue and cultured cells (RASMCs). Radial artery smooth muscle cells were cultured from arterial explants and loaded with the calcium fluorescent dye fura-2. Cells responded to endothelin-1 and a variety of other vasoconstrictors with rises in cytoplasmic calcium ([Ca2+]c). Arterial rings responded to endothelin-1 with an increase in tension. The response of both cells and arterial rings to endothelin-1 was characterized using the selective endothelin A receptor antagonist BQ123 and the endothelin B receptor antagonist BQ788. The RASMCs were found to express [Ca2+]c responses consistent with the expression of only the endothelin A receptor. Endothelin-1-mediated vasoconstriction in radial artery rings was unaffected by BQ788 but was completely blocked by BQ123. Using the selective radioligands [125I]-PD151242 and [125I]-BQ3020 and a combination of in vitro receptor autoradiography and isolated cell preparations, endothelin A receptors were confirmed to be present on RASMCs and on arterial sections, whereas endothelin B binding was barely detectable on native smooth muscle and on RASMCs.

Subjective patient outcomes following coronary artery bypass using the radial artery: results of a cross-sectional survey of harvest site complications and quality of life

OBJECTIVES

To assess patient-based outcomes following radial artery harvesting for coronary artery bypass surgery (CABG).

METHODS

A cross-sectional telephone survey of 127 patients who underwent radial artery grafting was undertaken. The parameters assessed included symptoms related to the radial artery harvest site (functional impairment, sensory symptoms, and wound infection) and health related quality of life.

RESULTS

A high percentage of patients (67.7%) reported altered sensation, in the hand, in particular around the thenar eminence, in the forearm, or in relation to the incision; this was self-limiting and clinically insignificant in the vast majority of patients. Twelve patients reported residual insignificant symptoms after a median follow-up of 17.5 months. Four patients reported a subjective decrease in grip strength. Patients reported a good quality of life, and there was no association between this and the presence or absence of symptoms related to radial artery harvest. Some patients volunteered a 'preference' for the radial artery harvest site when compared with concomitantly harvested long saphenous vein (LSV), and there was a lower wound infection rate at radial artery harvest sites compared with vein harvest sites (6 vs. 15%).

CONCLUSIONS

Sensory symptoms following radial artery procurement occur more frequently than previously reported, but are largely self-limiting and are usually clinically insignificant. Patients appear to have a good quality of life following CABG using the radial artery. Radial artery harvest may be associated with lower wound infection rates and greater patient satisfaction than LSV harvest, however, the presence of residual sensory symptoms may be of relevance when obtaining informed consent.

Predictors of radial artery patency for coronary bypass operations

BACKGROUND

Few data exist regarding angiographic predictors of radial artery patency for coronary bypass grafting, and the benefit of calcium antagonists is not clear.

METHODS

One hundred fifteen patients were studied who had myocardial revascularization with the radial artery plus internal mammary and vein grafts with 3.5 +/- 1.1 grafts per patient. Sixty-three patients received diltiazem and 52 patients did not. Base line and follow-up angiographies were analyzed 1 year postoperatively in 50 of these patients with a quantitative computerized method.

RESULTS

One hundred fourteen patients survived and were followed for 30.1 +/- 12.6 months. Patency for mammary grafts was 100%, for radial grafts it was 80%, and for saphenous vein grafts it was 68%. Patent radial artery grafts had significantly greater degree of stenosis in the native vessels than occluded grafts (73% +/- 14% vs 40% +/- 24%), (p = 0.0007; confidence interval = 95%). Radial artery patency increased to 92% when arteries with 70% or more stenosis were considered. No differences were observed for clinical and angiographic end points in the patients that received diltiazem compared with the rest who had not.

CONCLUSIONS

The degree of stenosis in the native coronary artery significantly influences the patency rate of radial artery grafts, independent of diltiazem.

Midterm results of complete arterial revascularization in more than 1,000 patients using an internal thoracic artery/radial artery T graft

OBJECTIVE

To report the authors' 7-year experience with the internal thoracic artery/radial artery (ITA/RA) T graft as the only conduits for myocardial revascularization in two- and three-vessel disease.

SUMMARY BACKGROUND DATA

One and two arterial conduits provide increasing survival benefit for coronary grafting and reduce the need for reintervention. Exclusive use of arterial conduits may provide further benefit.

METHODS

From October 1993 to November 2000, 1,020 patients underwent complete arterial revascularization with the ITA/RA T graft. The authors focus on the 909 having initial bypass, with a mean age of 60 and 20% age 70 or older. The incidence of triple-vessel disease was 73%, female gender 28%, diabetes mellitus 27%, peripheral vascular disease 11%, cerebrovascular disease 10%, and chronic obstructive pulmonary disease 6%; ejection fraction was less than 35% in 11%. Perioperative data were collected prospectively. Follow-up information was obtained at a mean of 35.4 months (range 1-88) and was 95% complete.

RESULTS

There were seven (0.08%) deaths within 30 days of surgery. The incidence of perioperative infarction was 3.3%, low cardiac output 2.7%, stroke 2.2%, reoperation for bleeding 3.8%, and deep sternal infection 0.8%. The actuarial survival rate was 90% at 5 years, freedom from infarction was 94%, freedom from catheterization was 83%, and freedom from reintervention (angioplasty or reoperation) was 93%.

CONCLUSION

The ITA/RA T graft for complete arterial revascularization is associated with a low rate of perioperative death and complications and 5-year survival and freedom from reintervention values consistent with other revascularization strategies.

Gadolinium-enhanced elliptically reordered three-dimensional MR angiography in the assessment of hand vascularization before radial artery harvest for coronary artery bypass grafting: first experience

RATIONALE AND OBJECTIVES

To assess the suitability of contrast-enhanced magnetic resonance angiography (MRA) in the preoperative evaluation of hand vasculature in potential candidates for radial artery bypass grafting.

METHODS

In 21 patients, gadobenate dimeglumine-enhanced, three-dimensional gradient-echo sequences of both hands were performed, as well as a Doppler ultrasound study with radial artery compression. Doppler findings were correlated with MRA, focusing on the assessment of anastomoses between the vascular bed of the ulnar and radial arteries.

RESULTS

One individual had to be excluded because of accidentally disclosed metal foreign bodies. Sufficient depiction of the hand vasculature was achieved in the remainder. Seventeen patients had evidence of adequate collateral flow between the ulnar and radial artery supply on Doppler ultrasound. Three patients exhibited inadequate collateral flow, with angiographic signs of vessel occlusion or missing collaterals between the palmar arches. Two patients presented with stenosis or occlusion of the radial artery. Magnetic resonance angiograms displayed great variations in hand vasculature and collateral formation, with no mismatch compared with Doppler ultrasound results.

CONCLUSIONS

Contrast-enhanced MRA displays vascularization of the hand in detail and supplies ultrasound flow measurements for radial artery harvest, with high-resolution angiographic data about possible vessel variations and the presence of anastomoses between the radial or ulnar artery supply.

Radial artery for myocardial revascularization: long-term clinical and angiographic results

BACKGROUND

To evaluate the long-term clinical and angiographic results of the radial artery (RA) as a graft in coronary artery bypass surgery.

METHODS

One hundred sixty-four patients had a RA graft from July 1992 to July 1994. In 128 (group A) the RA was connected end to side (115) or end to end (13) to the left internal mammary artery. In 36 (group B) the proximal anastomosis was on the ascending aorta.

RESULTS

Early mortality was 1.8% (group A 1.6% and group B 2.8%). Eight-year survival was 83.2%+/-3.2% (group A 82.1%+/-3.8% and group B 86.7%+/-6.2%, p = not significant [NS]), and event free survival was 80.1%+/-3.5% (group A 79.9%+/-4.4% and group B 80.2%+/-7.3%, p = NS). Sixty-one patients (37.2%) had an early angiography within 90 days from the operation. Patency rate of RA distal anastomoses were 98.9% (88 of 89), 98.7% in group A (77 of 78), 100% in group B (11 of 11; p = NS). After a mean of 48+/-27 months (6 to 96), 72 patients (51.1% of the survivors) had a new angiography. Patency rate of RA distal anastomoses was 95.6% (87 of 91), 93.8% in group A (61 of 65) and 100% in group B (26 of 26; p = NS). All the intermediate RA-LIMA anastomoses were patent at the early and late control. Patency rate for RA and IMAs was similar both early (88 of 89 versus 82 of 82; p = NS) and after 48+/-27 months (87 of 91 versus 93 of 93; p = NS).

CONCLUSIONS

Long-term clinical results after RA grafting are satisfying. Angiographic patency rate, both early and after 48 months, is higher than 90% and is similar to that obtained with internal mammary arteries. The site of the proximal anastomosis does not influence early and late patency.

Arm complications after radial artery procurement for coronary bypass operation

BACKGROUND

Radial arteries are being used frequently for coronary artery bypass conduits, and surgeons are appropriately concerned about the risks of ischemia, infection, and neurologic dysfunction of the "donor" arm. We present our record of donor site complications, with emphasis on the safety of radial usage in patients older than 65 years of age.

METHODS

A total of 343 radial arteries were removed from 217 patients, aged 37 to 83 years. Forty-nine (23%) of the patients were women; 126 of the radial arteries were from patients aged 65 years or older. Four patients died. In the remaining 213 patients, 338 donor arms were examined for at least 6 weeks postoperatively for evidence of infection, ischemia, hematoma, seroma, or paresthesia.

RESULTS

No donor arms developed symptoms of 'ischemia or motor dysfunction. Two of 338 (0.6%) arms developed hematomas requiring operative drainage. Relatively minor complications of stitch abscesses, skin dehiscence, superficial infection, and small hematomas or seromas affected another 14 arms (4.1%). Cutaneous paresthesias in the radial distribution of the lateral antebrachial cutaneous nerve or superficial branch of the radial nerve were noted postoperatively in 36 arms (10.7%). The risk of any arm complication occurring was 13% in the 65 and older group and 17% in those less than 65 years old (p = NS).

CONCLUSIONS

The risk of a major arm complication from radial artery harvesting for coronary bypass is low, even in patients of advanced age.

Myocardial revascularization with multiple arterial grafts: comparison between the radial artery and the right internal thoracic artery

BACKGROUND

Bilateral internal thoracic artery (ITA) harvesting is significantly underused, whereas the radial artery is being used with increasing frequency. We have retrospectively analyzed perioperative and short-term outcomes of patients receiving a radial artery versus those receiving a right ITA as a second arterial graft.

METHODS

Between February 1999 and May 2000, 250 patients underwent coronary artery bypass grafting using the radial artery (156 patients) or the right ITA (94 patients) in combination with the left ITA and, when required, the saphenous vein.

RESULTS

There was a higher prevalence of risk factors in the radial artery group. More coronary artery bypass graftings (p < 0.001) were performed with the radial artery. Operative mortality was not different (p = not significant). In the right ITA group there was more bleeding (p < 0.001) and a longer hospital stay (p < 0.001). Mean follow-up was 8.1 +/- 3.9 months. The probability of survival was similar (p = not significant).

CONCLUSIONS

The radial artery can extend the benefits of multiple arterial grafting to those patients who are usually excluded from bilateral ITA harvesting because of multiple risk factors. Perioperative and short-term results are good.