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

Palmar microcirculation does not deteriorate 2 years after radial artery harvesting—implications for reconstructive free forearm flap transfer

BACKGROUND

The functional consequences after radial artery-based forearm flaps for hand microcirculation remain unclear. We hypothesized that palmar microcirculation is compromised after radial artery removal in arteriosclerotic patients.

MATERIALS AND METHODS

A total number of 114 patients were included undergoing elective coronary revascularization using the radial artery of the nondominant forearm with non-pathological Allen's test. Palmar microcirculatory mapping with 1596 measurements was applied 2 years after removal of the radial artery regarding capillary flow, finger tip oxygenation, as well as postcapillary venous filling pressures throughout both hands using combined noninvasive real-time laser Doppler flowmetry and spectrophotometry.

RESULTS

Only 2/56 positions revealed a difference beyond a 5% threshold 25 +/- 5 months after radial artery removal. Superficial capillary blood flow decreased by 13% at the hypothenar eminence (242.0 +/- 153.6 vs 275.6 +/- 169.2, p = 0.009). Deep postcapillary venous filling pressure (8 mm) was significantly increased by 9% only at the fingertip of the fifth finger (112.4 +/- 49.7 vs 103.0 +/- 25.0, p = 0.033). No clinical signs of malperfusion were found after radial artery removal, and no patient was impaired in his daily palmar motor activity.

CONCLUSIONS

Pedicled removal of the radial artery does not compromise superficial or deep palmar capillary blood flow, finger tip oxygenation, or postcapillary venous filling pressures in a long-term perspective in arteriosclerotic patients. No clinical relevant signs of malperfusion or any deterioration of palmar motor function was encountered. The blood flow via the ulnar artery and the interosseal artery compensates palmar perfusion without microcirculatory deterioration even more than 2 years after removal of the radial artery.

Radial artery graft use and off-pump coronary artery bypass surgery outcome

Radial artery is commonly used as a conduit for surgical revascularization. There is scarce data on the effect of radial artery use on outcome following off-pump coronary artery bypass. We prospectively evaluated 591 patients undergoing off-pump coronary artery bypass. Radial artery grafts were used in 398 of these patients (mean age, 67.6 +/- 10.4 years; mean follow-up, 37.7 +/- 13.4 months). Symptom recurrence (angina, congestive heart failure), adverse cardiac events (myocardial infarction, coronary re-intervention, sudden cardiac death), and overall mortality were recorded. Multivariate Cox regression analysis was used to evaluate predictors of endpoints. Patients with and without radial artery grafts were similar with respect to preoperative risk factors. Recurrent angina developed in 29 patients, congestive heart failure in 5, and myocardial infarction in 9. Coronary arteriography was performed in 27 patients, and 23 underwent re-intervention. Radial artery graft was an independent predictor of increased symptom recurrence and adverse cardiac events. Patients with radial artery grafts also had a tendency towards more angina recurrence, coronary re-intervention, and sudden cardiac death.

Coronary artery bypass surgery in elderly people

An increasing number of elderly individuals are now undergoing coronary artery bypass surgery. Elderly patients, compared with patients of a younger age group, present for surgery with a greater burden of risk factors and reduced functional levels. Short-term outcomes are hence poorer in them. But symptom relief occurs in most survivors and is accompanied by excellent rates of long-term survival and a good quality of life. Therefore, an individualised risk-benefit profile must be carefully constructed by clinicians, taking into account several different factors and not just age alone. This review summarises the current concepts of coronary artery bypass surgery from the perspective of the very old.

Impact of radial artery cannulation for coronary angiography and angioplasty on radial artery function

The radial artery is commonly used as a conduit in coronary artery bypass grafting. No data exist on the effects of radial sheath insertion on radial artery function. Because many patients considered for coronary artery bypass grafting have had previous radial procedures, it is important to understand any effects radial sheath insertion may have on radial artery function. Twenty-two patients who underwent elective coronary angiography or angioplasty with a 6Fr sheath through the right radial artery were studied. Radial artery function was assessed using ultrasound to measure flow-mediated dilation (FMD). Reactive hyperemia was produced by 5-minute cuff inflation on the arm to suprasystolic pressures. Radial artery diameter was measured at rest and 1 minute after cuff deflation. FMD was expressed as percent change in radial diameter compared with at rest. In all cases, the left radial artery was studied as a control. Patients were studied before sheath insertion, immediately after sheath insertion, and 6 weeks after sheath insertion. The FMD of the cannulated arm was 13.2% before sheath insertion versus 3.6% immediately after sheath insertion (p <0.01) and 0.2% (p <0.01) 9 weeks after sheath insertion. In contrast, there were no significant changes in the noncannulated arm at either time point. In conclusion, radial artery sheath insertion for coronary angiography or angioplasty results in immediate and persistent blunting of FMD, suggesting severe vasomotor dysfunction. Radial artery sheath insertion has important effects on radial artery function that must be considered when selecting radial conduits for coronary artery bypass grafting.

Radial Artery Graft Treatment With Phenoxybenzamine is Clinically Safe and May Reduce Perioperative Myocardial Injury

BACKGROUND

Phenoxybenzamine effectively reduces radial artery (RA) spasm in vitro, but clinical data supporting its use during coronary revascularization are lacking. Therefore, the purpose of this study was to evaluate the clinical safety and efficacy of RA treatment with phenoxybenzamine.

METHODS

Data were collected prospectively on 698 patients who underwent coronary artery bypass grafting with a RA between 1997 and 2005. Of these, 311 patients received RA grafts incubated in 2 mg/mL phenoxybenzamine for 15 minutes, and 387 patients received RA grafts treated with verapamil and nitroglycerin (VG solution). Demographic, operative, and postoperative data were compared retrospectively using multivariate regression techniques.

RESULTS

The incidence of perioperative myocardial events (defined as either low cardiac output syndrome or perioperative myocardial infarction) was significantly reduced in the phenoxybenzamine group (6.8% vs 11.9%, phenoxybenzamine vs VG solution; p = 0.03). Perioperative myocardial enzyme release, as measured by postoperative maximum creatine kinase, was also reduced in the phenoxybenzamine group (743.0 +/- 677.9 vs 937.2 +/- 1236.8 U/L, phenoxybenzamine vs VG solution; p = 0.014). After adjusting for patient and procedural factors, the use of phenoxybenzamine was independently associated with reductions in peak creatine kinase (by -343.0 +/- 136.7 U/L; p = 0.012) and peak troponin T level (by -0.50 +/- 0.19 ng/mL; p = 0.010). No differences in vasopressor support, length of stay, or other complications were observed.

CONCLUSIONS

Treatment of RA grafts with phenoxybenzamine was associated with a reduction in perioperative myocardial injury and adverse cardiac events in this study population. Investigations to further evaluate the potential benefits of phenoxybenzamine in randomized settings are warranted.

Use of radial artery for coronary revascularization

Techniques of harvesting, strategies and techniques of implantation are presented. The radial artery, along with the internal thoracic artery, has wide application in coronary artery bypass grafting. The radial artery is implanted as a standard aorto-coronary, Y graft or extension graft. The application is extended by the use of sequential techniques.

Temperature Changes Stimulate Contraction in the Human Radial Artery and Affect Response to Vasoconstrictors

BACKGROUND

Radial artery conduits are increasingly used in coronary artery bypass grafting as an additional arterial graft to the internal thoracic artery. Their reactive nature remains a concern, often necessitating the routine use of topically applied vasodilators, such as glyceryl trinitrate, papaverine, phenoxybenzamine, or calcium channel antagonists, in theatre. During preparation prior to surgery and grafting, radial artery conduits are exposed to cooling and rewarming. We investigated how these temperature changes would affect radial artery contractility and how commonly used topical treatments might be used to prevent this.

METHODS

Human radial artery was obtained excess to surgery and arterial sections used in organ bath tension experiments or for the culture of smooth muscle cells from medial explants.

RESULTS

The radial artery responded to rapid cooling by the addition of 22 degrees C buffer with contraction. Gradual cooling, over a 20 to 30 minute period, reduced basal tension and the response to potassium chloride (KCl) and noradrenaline. Subsequent rewarming from 22 degrees C to 37 degrees C reestablished contraction at precooled levels and led to an elevation of the basal tension. Increases in tension measured in the radial artery were paralleled by increases in intracellular calcium in smooth muscle cells. Contraction induced by rapid temperature changes could be blocked by glyceryl trinitrate but not by phenoxybenzamine. Papaverine and calcium channel blockers had only limited activity.

CONCLUSIONS

Temperature changes commonly encountered in theatre during the preparation of radial artery grafts are likely to cause contraction. If rapid temperature change cannot be avoided during graft preparation, then topically applied glyceryl trinitrate will block these responses.

Skeletonized harvesting improves the early-term and mid-term perfect patency of a radial artery graft

OBJECTIVE

A radial artery (RA) graft is frequently used for coronary artery bypass grafting (CABG), but little information exists regarding the early- and mid-term patency associated with the harvesting procedure. The objective of this study is to compare the early- and mid-term patency of the RA graft obtained using non-skeletonized and skeletonized harvesting.

METHODS

Altogether, 131 patients and 159 anastomoses were studied. In 85 patients the RA was harvested non-skeletonized (group A: procedures between September 2000 and November 2002), whereas in 46 patients the RA was harvested skeletonized (group B: procedures between November 2002 and April 2004). Angiography results were analyzed before discharge [A: postoperative day (POD) 14.7 +/- 2.9, 75 patients, 90 anastomoses; B: POD 13.7 +/- 1.9, 38 patients, 47 anastomoses], and after 1 year (A: POD 386.8 +/- 149.3, 44 patients, 51 anastomoses; B: POD 267.1 +/- 148.7, 11 patients, 13 anastomoses).

RESULTS

There was no difference in patency between the two groups (group A vs group B, 96.7% vs 100%, P = not significant [NS], in the early-term, 96.2% vs 100%, P = NS, in the mid-term). However, the perfect patency rates for groups A and B were 86.7% and 98.1%, respectively, in the early-term (P = 0.034) and 77.5% and 100%, respectively, in the mid-term (P = 0.048). The location and severity of the target vessel did not influence the angiographic results.

CONCLUSION

The early- and mid-term patency of RA grafts was excellent, and skeletonized harvesting improved the perfect patency rates at both time points.

Radial artery diameter and vasodilatory properties after transradial coronary angiography

BACKGROUND

The radial artery is proposed as an alternative conduit in coronary revascularization. During the last years the transradial approach has, in many centers, emerged as the preferred technique in percutaneous diagnostic and interventional coronary procedures. This induces a trauma to the radial artery that possibly could influence its suitability as a bypass graft. In this study we assessed by ultrasound the long-term effects of transradial coronary angiography on the radial artery diameter and vasodilatory properties.

METHODS

Thirty patients were examined with high resolution ultrasound 10 to 14 months after a transradial coronary angiography. Radial artery baseline diameter and response to flow-mediated (FMD) and nitroglycerin-mediated vasodilation (NMD) were examined in the right radial artery with the unexposed left radial artery as control.

RESULTS

Right radial artery diameter was reduced compared with the left radial artery (2.58 +/- 0.38 vs 2.71 +/- 0.32 mm, p < 0.01). Both FMD and NMD were preserved in the exposed artery (FMD 8.4 +/- 8.0 vs 8.0 +/- 6.1%, NMD 15.5 +/- 6.8 vs 16.7 +/- 6.6%, both ns). Due to the reduced baseline diameter, the right radial lumen diameter remained significantly smaller after vasodilatory stimuli. Large interindividual differences were demonstrated.

CONCLUSIONS

The radial artery diameter is diminished one year after transradial coronary angiography while vasodilatory properties are preserved. The preserved vasodilatory capacity could favorably influence the suitability of the artery as bypass graft. However, with the long-term structural changes induced by transradial angiography, use of a catheter-exposed radial artery as a conduit in coronary artery revascularization should not be strongly recommended. With ultrasound, both structure and vasodilatory properties of a catheterization-exposed radial artery may be assessed in case the artery is considered as bypass material.

Patients With In-Stent Restenosis Have an Increased Risk of Mid-Term Venous Graft Failure

BACKGROUND

This study was designed to evaluate if patients in whom in-stent restenosis developed had an higher risk of early venous graft failure compared with normal patients.

METHODS

The study cohort comprised 120 patients (60 with previous in-stent restenosis and 60 controls) who received a total of 165 complementary venous grafts on the circumflex or right coronary artery system (84 in the restenosis group and 81 in the control group). All patients were prospectively followed-up and underwent reangiography at 5-years follow-up.

RESULTS

In the restenosis group, 28 venous grafts (33.%) were perfectly patent, 10 showed major irregularities, and 46 were occluded. In the control patients, 50 grafts (61.7%) were perfectly patent (p < 0.001 compared with the restenosis series), 12 showed major irregularities (p = .74), and 19 were occluded (p < 0.0001). In contrast, the 5-year outcome of internal thoracic artery grafts was not affected by history of in-stent restenosis.

CONCLUSIONS

Patients who developed in-stent restenosis have an higher risk of early venous graft failure compared with the control patients. Arterial grafts should probably be preferred in these patients.

Revascularization using satellite vein after radial artery harvested for coronary artery bypass grafting

The radial artery has been increasingly used for coronary artery bypass grafting and has excellent long-term patency rates. Hand claudication is one of the adverse effects after radial artery harvest. We reconstructed a radial artery using the satellite vein to prevent hand claudication. Pulsating blood flow at 35 cm/sec was evaluated using color Doppler echocardiography three months after surgery. This method makes it possible to use a radial artery in patients with a positive Allen test.

Noninvasive Midterm Follow-Up of Radial Artery Bypass Grafts With 16-Slice Computed Tomography

BACKGROUND

The standard invasive procedure to evaluate graft patency is selective coronary angiography. The recent introduction of a new generation of multidetector row computed tomography made possible the noninvasive study of grafts with excellent results in terms of visualization and resolution. We used computed tomography to study all patients with a radial artery graft operated on in 2002.

METHODS

Between April and October 2005, we reviewed all patients operated on by coronary artery bypass grafting at our institution between January and December 2002. A total of 62 patients received a radial artery graft. Of these, 22 were lost at the time of follow-up. The other 40 patients were enrolled for a multidetector row computed tomography study. Demographic and instrumental data were collected for all the patients. A total number of 145 grafts were studied, with complete and excellent visualization.

RESULTS

The scans revealed a 97.77% (44 of 45) patency rate for left internal mammary arteries, 90.57% (48 of 53) for vein grafts, and 73.91% (34 of 46) for radial arteries (mammary artery plus vein grafts versus radial artery patency, p < 0.001). If analyzed for target vessel, we found the poorest result of radial grafts when placed on the right coronary artery (40% [2 of 5] patency rate).

CONCLUSIONS

Noninvasive control of previously bypassed patients is feasible, with no discomfort for them and excellent visualization of grafts. The use of the radial artery as a conduit for bypass graft can be achieved with good results, after a careful choice of the target vessel.

Thromboxane Receptor Stimulation Suppresses Guanylate Cyclase-Mediated Relaxation of Radial Arteries

BACKGROUND

The internal mammary artery (IMA) and the radial artery (RA) are routinely used in coronary artery bypass grafting. However, RA grafts have a higher incidence of postoperative vasospasm and comparatively poor patency rates. The present study was undertaken to investigate the signaling pathways mediating contraction and relaxation in the IMA and RA with the aim of better understanding the mechanism underlying the propensity of RA grafts to spasm.

METHODS

We examined the contractile responses of the IMA and RA to KCl (a depolarizing agent), phenylephrine (an alpha-adrenergic agonist), and U46619 (a thromboxane analogue).

RESULTS

Contractions induced by KCl or U46619 did not significantly differ in IMA and RA. By contrast, phenylephrine evoked significantly greater contraction of the IMA than the RA. Contractions induced by both phenylephrine and U46619 were dose-dependently inhibited by nifedipine (an L-type calcium channel blocker). Estimation of thromboxane A2 (TxA2) and prostacyclin (PGI2) synthesis revealed that the TxA2 to PGI2 ratio in the RA was twice that in the IMA. Moreover, acetylcholine-induced and nitroglycerin-induced relaxation of RA precontracted with U46619 was significantly impaired, as compared with RA precontracted with phenylephrine. These data suggest that inhibition of nitroglycerin-induced soluble guanylate cyclase activity by U46619 was at least partially responsible for the diminished vasodilatory response of RA to nitric oxide.

CONCLUSIONS

Our findings suggest that by reducing nitric oxide-stimulated soluble guanylate cyclase activity, the higher TxA2 to PGI2 ratios in RA, and the elevated serum TxA2 levels seen during coronary artery bypass grafting operations, may underlie the vasospasm and poor patency rates seen with the RA.

Long-term palmar microcirculation after radial artery harvesting: an observational study

BACKGROUND

The aim of this study was to assess palmar microcirculation in a long-term follow-up after radial artery harvesting for coronary revascularization.

METHODS

One hundred fourteen patients (100 male; aged 61.7 +/- 6.7 years; preoperative New York Heart Association 2.3 +/- 0.6, ejection fraction 61.4% +/- 13.9%) were included after undergoing elective coronary revascularization using the radial artery of the nondominant forearm with a nonpathologic Allen's test. Superficial and deep tissue oxygen saturation (SO2), postcapillary venous filling pressure (rHb), capillary blood flow, and capillary blood flow velocity were determined at a mean 25 +/- 5 months after surgery using a combined laser Doppler spectrophotometry system.

RESULTS

At 2-mm tissue depth, there was a small, but significant, decrease of 3% of superficial SO2 at the thumb and the thenar eminence (D1: 75.3% +/- 8.9% versus 77.6% +/- 9.7%, p = 0.003; thenar: 71.5% +/- 10.5% versus 73.2% +/- 8.2%, p = 0.027). Deep palmar SO2 was changed significantly at 5 of 7 positions by 3%. Deep postcapillary venous filling pressure (8 mm) was significantly increased by 9% only at the fingertip of the fifth finger (112.4 +/- 49.7 versus 103.0 +/- 25.0, p = 0.033), while superficial capillary blood flow decreased by 13% at only 1 of 7 positions at the hypothenar eminence (242.0 +/- 153.6 versus 275.6 +/- 169.2, p = 0.009). Overall, only 2 of 56 positions exceeded a given threshold of 5% change of microcirculation. No clinical signs of malperfusion were found (postoperative New York Heart Association 1.1 +/- 0.4, p < 0.05), and no patient was impaired in daily palmar motor activity.

CONCLUSIONS

Long-term objective evaluation of superficial and deep palmar microcirculation confirms that radial artery harvesting for coronary revascularization does not compromise palmar microcirculation.

Vascular-wall remodeling of 3 human bypass vessels: organ culture and smooth muscle cell properties

OBJECTIVES

Late graft occlusions after coronary artery bypass grafting have been ascribed to neointimal hyperplasia. Given the pivotal role of smooth muscle cells in the pathogenesis of neointimal hyperplasia and the phenotypic heterogeneity of smooth muscle cells across vessels, we hypothesized that differences in long-term graft patency are at least partly related to differences in smooth muscle cell properties. The aim of the present study was to compare the vascular-wall remodeling of human internal thoracic artery, radial artery, and saphenous vein bypass conduits.

METHODS

We evaluated the intimal thickening of the human graft segments in organ cultures (histopathology, morphometric, and immunofluorescence analyses) and assessed the properties of cultured smooth muscle cells isolated from these vessels in terms of cell proliferation (tritiated thymidine incorporation), migration (modified Boyden chamber), and collagen synthesis (tritiated proline incorporation).

RESULTS

The total vessel-wall growth index and the intimal growth index were significantly higher for saphenous vein rings than for radial artery and internal thoracic artery rings. Immunofluorescence analyses showed predominant involvement of smooth muscle cells in neointimal growth induced by organ culture of saphenous vein rings. Cell proliferation was significantly higher in saphenous vein smooth muscle cells than in radial artery smooth muscle cells and significantly higher in radial artery smooth muscle cells than in internal thoracic artery smooth muscle cells. Migration of smooth muscle cells from saphenous vein grafts was significantly greater than from internal thoracic artery or radial artery grafts. Collagen synthesis was similar in smooth muscle cells from internal thoracic artery, radial artery, and saphenous vein grafts.

CONCLUSIONS

Ex vivo vascular-wall remodeling and smooth muscle cell intrinsic growth and migratory properties are dissimilar between arterial and venous grafts and might shed light on reported angiographic patency rates of these grafts.

The role of vessel wall physiology in predicting coronary bypass graft patency

Not applicable.

Arterial versus venous bypass grafts in patients with in-stent restenosis

BACKGROUND

In patients who develop in-stent restenosis, successful revascularization can be difficult to achieve using percutaneous methods. This study was designed to verify the surgical results in this setting and to evaluate the potential beneficial role of arterial bypass conduits.

METHODS AND RESULTS

Sixty consecutive coronary artery bypass patients with previous in-stent restenosis and 60 control cases were randomly assigned to receive an arterial conduit (either right internal thoracic or radial artery; study group) or a great saphenous vein graft (control group) on the first obtuse marginal artery to complete the surgical revascularization procedure. At a mean follow-up of 52+/-11 months, patients were reassessed clinically and by angiography. Freedom from clinical and instrumental evidence of ischemia recurrence was found in 19 of 60 subjects in the study group versus 45 of 60 in the control series (P=0.01). The results of the arterial grafts were excellent in both the study and control groups (right internal thoracic artery patency rate, 19 of 20 for both, and radial artery patency rate, 20 of 20 versus 19 of 20; P=0.99). Saphenous vein grafts showed lower patency rate than arterial grafts in both series and had extremely high failure rate in the study group (patency rate, 10 of 20 in the study group versus 18 of 20 in the control group; P=0.001). Use of venous graft was an independent predictor of failure in the study group, whereas hypercholesterolemia was associated with graft failure in both series.

CONCLUSIONS

Venous grafts have an high incidence of failure among cases who previously developed in-stent restenosis, whereas the use of arterial conduits can improve the angiographic and clinical results. Arterial grafts should probably be the first surgical choice in this patient population.

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.

Radial artery grafting

After its recent reintroduction in coronary surgery the radial artery is gaining wide acceptance as complementary arterial conduits for surgical myocardial revascularization. The main technical aspects of radial artery harvesting, the biological and vasoactive characteristics of radial artery grafts as well as the mid- to long-term angiographic results and the role of the antispatic therapy are reviewed.

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.

Treatment of Unprotected Left Main Coronary Artery Stenosis in the Drug-Eluting Stent Era

Coronary angiography is often inadequate for estimating the severity of ambiguous left main coronary artery (LMCA) stenoses. Our assessment of these lesions can be improved by the techniques of intravascular ultrasound and fractional flow reserve which provide indices of stenosis severity to enable the prediction of future events and planning of treatment. For patients requiring LMCA revascularization, coronary artery bypass graft (CABG) surgery has been gold standard for decades. However, this technique continues to be limited by factors such as periprocedural mortality, prolonged hospital stay and rehabilitation, and long-term graft patency. LMCA stenosis remains one of the few serious challenges for the interventional cardiologists and, in the bare metal stent era, the long-term results were not sufficient to replace CABG surgery, mainly because of the high restenosis rate. Drug-eluting stents (DES) have dramatically reduced the restenosis rate and early results in small series (approximately 300 patients in total) treated with DES in LMCA have been encouraging, especially for lesions at the ostium and in the left main shaft. Before changes are made in the guidelines for treatment, we must wait for a refinement in the technique and stent design used for bifurcational left main lesion and the results of randomized, specific multicenter studies (SYNTAX trial). It is likely that, for selected patients, LMCA stenosis will be regarded as an indication for PCI.

Graft harvesting for revascularization in the head and neck

The techniques for revascularization in the neurocranium, skull base, and neck continue to evolve at an exciting pace. In this body of literature, however, techniques for harvesting radial artery and saphenous vein grafts are mainly reported using traditional open techniques. Minimally invasive procedures are fast becoming an alternative to open techniques in many fields and have the potential to become the standard of care. The cardiovascular literature is replete with reports of endoscopically harvested vascular grafts. This article reviews both methods, since the current state of the art involves knowledge of open and endoscopic harvesting techniques.

Do Angiographic Results From Symptom-Directed Studies Reflect True Graft Patency?

BACKGROUND

Coronary artery graft patency results have been obtained from repeat angiograms in patients who presented with evidence of ischemia. The purpose of this study is to compare protocol-directed angiographic results from a randomized clinical trial with symptom-directed angiography in nontrial patients.

METHODS

Repeat angiography after primary isolated coronary artery bypass grafting was performed in 337 of 2,259 patients between July 1996 and September 2004. Patients were divided into two groups: 596 graft angiograms in 192 trial patients were compared with 389 graft angiograms in 142 nontrial patients. The mean interval from surgery was 1,306 +/- 800 days versus 1,119 +/- 777 days, respectively. Grafting techniques were similar in both groups except that the right internal thoracic artery was used almost exclusively as a free graft in the trial patients. Angiographic outcomes were defined as patent (stenosis <80%) or failure (stenosis > or =80%, occlusion, or the string sign). Comparisons of trial versus nontrial grafts were made using a generalized linear mixed model. Five-year estimates of graft patency were made using survival analyses accounting for interval censoring.

RESULTS

The odds ratio for graft failure for nontrial compared with trial patient grafts was 2.6 (95% confidence interval, 1.6 to 4.3; p < 0.001). Cumulative patency estimates for all grafts at 5 years were trial 91% versus nontrial 83%, p = 0.004. Five-year estimates for individual conduits were left internal thoracic artery, 99% versus 92%, p = 0.002; right internal thoracic artery, 86% versus 87%, p = 0.8; radial artery, 87% versus 86%, p = 0.6; and saphenous vein, 86% versus 56%, p = 0.003.

CONCLUSIONS

Graft patency rates were superior in the trial compared with nontrial patients. Symptom-directed graft failure rates were approximately double those of trial patients.

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.

Radial artery grafts in women: utilization and results

BACKGROUND

Despite a known survival benefit with the use of the left internal mammary artery, it is used less frequently in women when compared with men. This study evaluated the hypotheses that the radial artery graft is used less frequently in women compared with men, that the radial artery is smaller in women compared with men, and that the use of the radial artery influences operative mortality and long-term survival in women.

METHODS

The use of a radial artery graft was evaluated in 2,633 patients who underwent isolated coronary artery bypass. Radial artery size and flow were compared in 207 patients who had intraoperative radial artery diameter and flow measurements. Propensity scoring was utilized to compare short- and long-term outcomes in a matched cohort of 588 women.

RESULTS

Of 862 women (33%) who had isolated coronary artery bypass grafting, only 301 (35%) received a radial artery graft versus 44% of men (786 of 1,771, p < 0.001). Radial artery size and flow were significantly less in women. Operative mortality was not different between women with a radial artery graft and women without; however, 5-year survival was significantly better in women with a radial artery graft than in those without.

CONCLUSIONS

Women received fewer radial artery grafts than men. Radial artery size and flow were significantly less in women than in men. Use of a radial artery graft did not influence operative mortality among women. However, 5-year survival among women who received a radial artery graft was significantly better than among women who did not.

Chronic compensatory increase in ulnar flow and accelerated atherosclerosis after radial artery removal for coronary artery bypass

BACKGROUND

Only scant information is available on the chronic consequences of radial artery removal for coronary artery bypass surgery on forearm circulation.

METHODS

Twenty-five patients submitted to radial artery removal for coronary artery bypass were submitted to serial Doppler echocardiographic evaluation of the flow and morphology of the forearm arteries.

RESULTS

The peak systolic velocity of the ulnar artery of the operated side was significantly higher than that of the control site. The intimal-medial thickness of the ulnar artery was always significantly higher on the operated side, and this difference reached statistical significance at 10 years' follow-up. There was a significantly higher prevalence of atherosclerotic plaques in the ulnar artery of the operated versus control arm (7/25 vs 0/25, P = .03).

CONCLUSION

Radial artery removal for coronary artery bypass surgery leads to a chronic increase in ulnar flow accompanied by increased intimal-medial thickness and accelerated atherosclerotic disease. These findings might have potentially important implications for surgical indications and patient management.

Coronary Artery Bypass Grafts: Assessment with Multidetector CT in the Early and Late Postoperative Settings

Coronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease. It is well known that the long-term clinical outcome after myocardial revascularization depends on the patency of the bypass grafts. In the past, invasive coronary angiography was used to assess the status of the grafts and check for graft occlusion. Recently, computed tomography (CT), particularly multidetector CT with electrocardiographic gating, has emerged as an important diagnostic tool for evaluation of CABGs in both the early (< or =1 month) and late (>1 month) postoperative settings. A variety of postoperative complications may manifest as dyspnea and chest pain, thereby mimicking recurrent angina secondary to graft occlusion. Owing to its improved spatial resolution compared with that of earlier-generation CT scanners and its ability to produce three-dimensional and multiplanar images, multidetector CT has assumed an integral role in characterization of graft patency while allowing investigation of alternative postoperative complications. In addition, the expanded capabilities of volumetric imaging may provide valuable information in preoperative planning for repeat CABG surgery.

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.

Palmar Microcirculation After Harvesting of the Radial Artery in Coronary Revascularization

PURPOSE

To evaluate real-time parameters of palmar microcirculation before and after harvesting of the radial artery in coronary revascularization using a laser Doppler flowmetry and remission spectroscopy system (O2C).

DESCRIPTION

Fifteen patients (11 males, 54 +/- 4 years, mean New York Heart Association [NYHA] class of 2.3 +/- 0.3) were prospectively scheduled with control measurements of the fingertips of D1, D3, and D5 at base line, after suprasystolic, and after selective radial or ulnar compression for tissue oxygen saturation (SO2), postcapillary venous recombinant hemoglobin (rHb) concentration, superficial (2 mm) blood flow, and deep (8 mm) blood flow.

EVALUATION

Preoperatively during suprasystolic compression SO2 decreased significantly for the fingertips of D1, D3, and D5 by -58%, -74%, and -63%, respectively (p < 0.05). Radial compression reduced SO2 for all fingertips (-12%, -14%, and -16%), as did ulnar compression (-24%, -18%, and -10%). rHb did not change significantly for either compression type. Superficial and deep blood flow decreased significantly after suprasystolic and only slightly after radial and ulnar compression at either side. No side differences were noted. After radial artery harvesting, microcirculatory parameters did not change considerably versus preoperatively.

CONCLUSIONS

Radial artery harvesting does not remarkably change microcirculatory parameters of the hand. The O2C system is a safe and quantitative method to assess both preoperatively and postoperatively the palmar microcirculation and therefore adds further functional clinical information.

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.

The radial artery for coronary artery bypass grafting

Coronary artery bypass grafting (CABG) is the standard surgical procedure for the treatment of advanced coronary artery disease. CABG surgery has been demonstrated to improve symptoms and, in specific subgroups of patients, to prolong life. Despite its success, the long-term outcome of coronary bypass surgery is strongly influenced by the fate of the vascular conduits used. Previous long-term studies have shown unsatisfactory patency of saphenous vein grafts used for myocardial revascularisation, compared with internal mammary artery grafts. Recently, the use of radial artery for CABG has enjoyed a revival, on the basis of the belief that it will help improving long-term results of coronary operations. The recent reports of encouraging mid-term and long-term patency rates of the radial artery, supports its continued use as a bypass conduit. In this paper, we review the current knowledge about the radial artery as a bypass graft, with special emphasis on the clinical results.

Arterial Conduits Update

Arterial grafting for coronary artery disease has been practiced routinely at the Epworth Hospital for 20 years. Bilateral versus single internal thoracic artery grafts is associated with improved survival, which progressively increased over the 20 years of post-surgery. The average increase in survival was 15% at 20 years. The question of whether to use the radial artery or the saphenous vein graft as supplementary grafts remains unanswered. Current patency data suggest that there is a marginal advantage of radial artery over saphenous graft patency, particularly between 5 and 10 years after surgery. However, there appears to be improved patency of the saphenous vein when used as a coronary artery bypass with the advent of aspirin, lipid-lowering and anti-hypertensive therapy.

A randomized comparison of radial-artery and saphenous-vein coronary bypass grafts

BACKGROUND

In the past decade, the radial artery has frequently been used for coronary bypass surgery despite concern regarding the possibility of graft spasm. Graft patency is a key predictor of long-term survival. We therefore sought to determine the relative patency rate of radial-artery and saphenous-vein grafts in a randomized trial in which we controlled for bias in the selection of patients and vessels.

METHODS

We enrolled 561 patients at 13 centers. The left internal thoracic artery was used to bypass the anterior circulation. The radial-artery graft was randomly assigned to bypass the major vessel in either the inferior (right coronary) territory or the lateral (circumflex) territory, with the saphenous-vein graft used for the opposing territory (control). The primary end point was graft occlusion, determined by angiography 8 to 12 months postoperatively.

RESULTS

Angiography was performed at one year in 440 patients: 8.2 percent of radial-artery grafts and 13.6 percent of saphenous-vein grafts were completely occluded (P=0.009). Diffuse narrowing of the graft (the angiographic "string sign") was present in 7.0 percent of radial-artery grafts and only 0.9 percent of saphenous-vein grafts (P=0.001). The absence of severe native-vessel stenosis was associated with an increased risk of occlusion of the radial-artery graft and diffuse narrowing of the graft. Harvesting of the radial artery was well tolerated.

CONCLUSIONS

Radial-artery grafts are associated with a lower rate of graft occlusion at one year than are saphenous-vein grafts. Because the patency of radial-artery grafts depends on the severity of native-vessel stenosis, such grafts should preferentially be used for target vessels with high-grade lesions.

Radial artery as a conduit for coronary artery bypass graft

Since its resurgence in the 1990s, some 30 years after its abandonment as an alternative conduit, the radial artery has rapidly gained popularity. This article describes the application of this conduit in coronary grafting and details the controversies surrounding its use. A historical account as well as technical aspects such as operative technique are also discussed.

Five-Year Angiographic Patency of Radial Artery Bypass Grafts

Background— Little information exists regarding mid-term and long-term patency of radial artery grafts.

Methods and Results— We performed restudy coronary angiography at 5.2±0.4 years after surgery on 50 asymptomatic patients who had undergone coronary artery bypass graft surgery, using at least 1 radial artery graft, to determine both graft patency and presence of narrowing. We examined preoperative clinical or angiographic variables that might predict graft occlusion. Radial artery graft patency was 89%, with 91% of grafts free of narrowing. Preoperative New York Heart Association anginal class ≤2, target vessel proximal stenosis ≤70%, and small target vessel supply territory were predictive of graft occlusion.

Conclusion— At 5 years after surgery, radial artery grafts have disease-free patency rates that are similar to other graft types.

Histamine H1 and H2 receptor–mediated vasoreactivity of human internal thoracic and radial arteries

BACKGROUND

Although internal thoracic arteries (ITAs) and radial arteries (RAs) have been shown to have similar patency, RAs tend to be more vasospastic postoperatively compared with ITAs. Therefore, the purpose of this study was to examine the effect of histamine subclass 1 (H1) receptors and histamine subclass 2 (H2) receptors on vasoreactivity in human ITAs and RAs.

METHODS

Vessels were obtained from coronary artery bypass grafting patients. Human arterial rings (2 mm) were mounted in tissue baths, and baseline contractility was determined. Histamine concentration response curves (10(-9)-10(-3) mol/L) were performed in the absence or presence of diphenhydramine (H1 antagonist, 10(-4) mol/L) or famotidine (H2 antagonist, 10(-4) mol/L). Comparison of curves was performed by 2-way analysis of variance with repeated measures and a Bonferroni post-t test.

RESULTS

Maximal contraction to histamine was significantly greater in RA (8.3 +/- 0.8 g, n = 6) than in ITA (2.9 +/- 0.3, n = 6), (P < .05). However, there was no difference in sensitivity. Histamine-mediated responses of both RA and ITA were blocked by pre-exposure to H1 antagonist, whereas an H2 antagonist only partially inhibited RA responses while blocking most of the ITA response to histamine.

CONCLUSION

These studies suggest that H1 receptors alone cause contraction in RA but not in ITA, which may have potential linkage to patency and vasospasm. Further studies are necessary to identify the exact role of H2 receptors in ITA.